JP7324140B2 - Motor drive with precharging circuit - Google Patents

Description

The present invention relates to a motor drive having a precharging circuit.

In machine tools, forging machines, injection molding machines, industrial machines, or motor drive devices that control the drive of motors in various robots, AC power input from an AC power supply is converted into DC power by a rectifier circuit and converted to DC power. The DC voltage is output to the link, and the DC voltage in the DC link is converted into AC power by an inverter, and this AC power is supplied as driving power for the motor. A "DC link" refers to a circuit portion that electrically connects the DC output side of a rectifier circuit and the DC input side of an inverter. , or may also be called a "direct current intermediate circuit".

The DC link is provided with a capacitor (DC link capacitor) that has a function of suppressing pulsation of the DC output of the rectifier circuit and a function of accumulating DC power. A DC link capacitor is also called a smoothing capacitor.

A capacitor provided in the DC link needs to be charged to a predetermined level of voltage from immediately after the motor drive device starts to before the motor starts to drive (that is, before the inverter starts the power conversion operation). This charging is commonly referred to as pre-charging (or initial charging).

A large inrush current is output from the rectifier circuit to the DC link immediately after pre-charging is started in a state where no energy is stored in the capacitor. The larger the capacitance of the capacitor, the larger the inrush current. As a countermeasure against this inrush current, a preliminary charging circuit (initial charging circuit) is generally provided on the AC input side or the DC output side of the rectifier circuit. The precharging circuit has, for example, a charging resistor and a charging resistor bypass switch connected in parallel with the charging resistor. During the precharging period of the capacitor, the charging resistor is included in the current path by opening (turning off) the charging resistor bypass switch. During normal operation when the motor driving device drives the motor, the charging resistor bypass switch is closed (turned on) to form a current path in which the charging resistor is bypassed.

In addition, since a large amount of energy is accumulated in the capacitor provided in the DC link, the capacitor provided in the DC link should It is desirable to remove the accumulated charge as quickly as possible. For this reason, a discharge circuit is provided in the DC link of the motor drive device in order to discharge the charge accumulated in the capacitor in a short period of time. The discharge circuit has, for example, a discharge switch and a discharge resistor connected in series with the discharge switch. When the discharge switch is closed (close operation), the discharge resistor and capacitor are electrically connected to perform a discharge operation to discharge the DC power in the DC link, and when the switch in the discharge circuit is opened (opening operation), the electrical connection between the discharge resistor and the capacitor is cut off, no discharge operation is performed, and a non-discharge operation state is established.

During normal operation when the pre-charging operation is completed and the motor driver drives the motor, the charging resistance bypass switch remains closed (on). If any abnormality occurs in the motor, the motor driving device for driving the motor, or the machine provided with the motor during the normal operation period, the control unit in the motor driving device causes the motor to stop in an emergency. Receive an emergency stop signal. Upon receiving the emergency stop signal, the control unit opens an electromagnetic contactor, which is an opening/closing unit provided on the AC power supply side of the motor drive device, and closes the discharge switch. As a result, the discharge resistor and the capacitor are electrically connected, and DC power in the DC link flows into the discharge resistor and is consumed as heat (discharge operation). After that, when the control unit in the motor drive device receives an emergency stop cancellation signal for canceling the emergency stop of the motor, the control unit closes the electromagnetic contactor, opens the charging resistor bypass switch, and discharges the switch. open up. As a result, the capacitor provided in the DC link is charged up to a predetermined charging voltage by the current flowing through the charging resistor and the rectifying circuit (pre-charging operation). When the capacitor is charged to a predetermined charging voltage, the charging resistor bypass switch is closed to complete precharging.

2. Description of the Related Art Various types of motor driving devices are known which are equipped with a pre-charging circuit and a discharging circuit.

For example, a control device for an AC rotating machine having a stator provided with m sets (m is a natural number of 2 or more) of windings of n phases (n is a natural number of 2 or more) and a rotor provided with permanent magnets, A switching element on the positive electrode side connected to the positive electrode side of the power supply and a switching element on the negative electrode side connected to the negative electrode side of the DC power supply are connected in series, and the connection point of the series connection is connected to the winding of the corresponding phase. n sets of series circuits are provided corresponding to each of the n phases; dq-axis current control for controlling the current flowing through the windings is performed on a dq-axis rotating coordinate system consisting of the q-axis determined in a direction advanced by 90 degrees in electrical angle to turn each of the switching elements on and off. a switching control unit for controlling; a fault detection unit for detecting short-circuit and open-circuit faults in each of the switching elements; a detection unit, wherein, when the failure detection unit detects a failure of the switching element, the switching control unit performs the dq-axis current control for the set of power converters in which the switching element has failed. stop the on/off control of the switching element by at least the switching element of each phase on the same positive side or negative side as the failed switching element is turned on in the case of a short circuit failure, and turned off in the case of an open failure and for the pair of power converters in which the switching element has not failed, the on/off control of the switching element by the dq-axis current control is continued, and the winding of the failed pair detected by the operating state detection unit is continued. A control device for an AC rotating machine is known that changes the current component of the d-axis according to the state of the AC rotating machine related to a line (see, for example, Patent Document 1).

For example, temperature detection means (SD*#; *=c, u, v, w: #=p, n) for detecting the temperature of the switching element and the temperature (Vf) detected by the temperature detection means are used as inputs. , a state determining means (38, 40, 62) for outputting a determination result as to whether or not the temperature-related state of the switching element is a specific state; and the temperature detecting means and the state determining means. Control means (14) provided in a second area different from the area, for controlling the switching element, and transmission means (18) for transmitting the judgment result output from the state judgment means to the control means. A driving device for a switching element is known, wherein the control means comprises a processing means for performing a process of changing the control of the switching element based on the judgment result transmitted via the transmission means. (See Patent Document 2, for example).

For example, a motor equipped with a permanent magnet that is magnetized to change magnetic flux, an inverter that converts DC power supplied from a DC power supply via a capacitor into AC power for driving the motor, and Magnetizing current output means for outputting a magnetizing current for magnetizing the permanent magnet, current interrupting means for interrupting a current flowing from the capacitor to the DC power supply, and outputting the magnetizing current from the inverter by the magnetizing current output means. In order to do so, boosting means for boosting the DC voltage applied to the DC side of the inverter by interrupting the current by the current interrupting means and controlling the inverter; There is known a motor drive device comprising DC voltage control means for controlling the DC voltage boosted by the voltage boosted by the motor drive device (see, for example, Patent Document 3).

For example, an energy storage element, an AC motor in which the stator windings are star-connected, and a power converter in which a semiconductor switch is on/off controlled so as to transfer power between the energy storage element and the AC motor. , wherein at least two motor driving devices are connected in parallel with the energy storage element as a direct-current link portion, in a motor driving system in which a first power converter drives a first A secondary battery connected between a neutral point of each stator winding of one AC motor and a second AC motor driven by a second power converter and one end of the DC link section. a switch connected between a first power converter and a first AC motor; an AC power supply connected between the AC side of the first power converter and said switch; In the OFF state, the first power converter is operated as a rectifier to store DC power in the DC link unit, and the second power converter is operated to use the second AC motor as a reactor. and a temperature detection means for detecting the temperature of the second AC motor, wherein the control means controls the temperature of the second AC motor. A motor drive system is known that controls the charging current of the secondary battery according to a temperature value detected by a detecting means (see, for example, Patent Document 4).

For example, a converter that receives an input AC voltage and performs AC-DC power conversion, an inverter that receives DC power and performs DC-AC power conversion, and a charging/discharging device connected in parallel to a DC link section between the converter and the inverter A motor drive device comprising a control circuit and a capacitor, wherein electrical energy is supplied from the capacitor to the DC link section through the charge/discharge control circuit, wherein the charge/discharge control circuit supplies the electrical energy stored in the capacitor. 2. Description of the Related Art A motor control device is known that has a circuit that steps down and discharges the voltage of a capacitor when discharging and a circuit that steps up and discharges the voltage of a capacitor, or has a circuit that steps up and discharges the voltage of a capacitor (see, for example, Patent Documents 5).

Retable 2017/098555 JP 2013-247426 A JP 2012-223022 A JP 2012-110139 A JP 2009-232537 A

The input of the emergency stop signal for emergency stop of the motor and the emergency stop release signal for canceling the emergency stop to the control unit in the motor drive device is controlled by the ladder program in the host control device of the motor drive device, or It is also controlled by the operator operating the emergency stop button of the host controller. If there is an error in the ladder program or if the operator frequently presses the emergency stop button, the emergency stop signal and the emergency stop release signal may be alternately input to the control unit in the motor drive device in a short period of time. Become. As a result, the charging resistor bypass switch in the precharging circuit and the discharging switch in the discharging circuit are repeatedly closed and opened, possibly damaging the precharging circuit. For example, in a pre-charging circuit, when a charging resistor bypass switch is opened, current flows through the charging resistor, causing the charging resistor to generate heat and raise its temperature. When the charging resistor bypass switch is closed, a current path is formed in which the charging resistor is bypassed, and no current flows through the charging resistor, so no heat is generated, and the temperature of the charging resistor gradually decreases over time. However, if the charging resistor bypass switch in the pre-charging circuit is repeatedly closed and opened within a short period of time, the charging resistor cannot be sufficiently cooled, and heat continues to accumulate in the charging resistor, resulting in an increase in temperature. continue. In general, the discharge resistor in the discharge circuit is assumed to be consumed by heat, so its heat resistance is relatively large. , low heat resistance. Therefore, when the emergency stop signal and the emergency stop release signal are alternately input in a short period of time, the charging resistor bypass switch is repeatedly closed and opened, and the temperature of the charging resistor continues to rise. , the charging resistor melts, leading to damage to the pre-charging circuit. Therefore, there is a demand for a motor driving device having a pre-charging circuit that can avoid damage due to heat generation even if an emergency stop signal and an emergency stop release signal are alternately input in a short period of time.

According to one aspect of the present disclosure, a motor drive device includes a rectifier circuit that converts AC power input from an AC power source into DC power and outputs the DC power, and a capacitor that is provided in a DC link on the DC output side of the rectifier circuit. , an inverter that converts DC power in a DC link into AC power for driving a motor and outputs the AC power, a charging resistor bypass switch, and a charging resistor connected in parallel to the charging resistor bypass switch, a preliminary charging circuit comprising: A pre-charging circuit for pre-charging a capacitor with power flowing through a charging resistor bypass switch or a charging resistor and a rectifying circuit, and a discharging circuit provided in a DC link, wherein the discharging circuit and the capacitor are electrically connected. The discharging circuit selectively switches between the discharging operation of discharging the DC power accumulated in the capacitor and the non-discharging operation of disconnecting the electrical connection between the discharging circuit and the capacitor, and the estimated temperature of the charging resistor is sequentially calculated. and a controller for controlling the pre-charge circuit and the discharge circuit, wherein the controller controls the discharge circuit to maintain the non-discharge operation when the estimated temperature exceeds a predetermined temperature threshold. .

According to one aspect of the present disclosure, it is possible to realize a motor drive device having a pre-charging circuit that can avoid damage due to heat generation even if an emergency stop signal and an emergency stop cancellation signal are alternately input in a short period of time. .

1 illustrates a motor drive device according to first and second embodiments of the present disclosure; FIG. FIG. 4 is a diagram showing a case where a pre-charging circuit is provided on the DC output side of the rectifier circuit in the motor driving devices according to the first and second embodiments of the present disclosure; FIG. 3 is a diagram illustrating operations of an opening/closing unit, a pre-charging circuit, and a discharging circuit in a conventional motor drive device; 4 is a flow chart showing operation flows of a pre-charging circuit, a discharging circuit, and an opening/closing unit in the motor driving device according to the first embodiment of the present disclosure; FIG. 4 is a diagram for explaining estimated temperature calculation processing by a temperature estimating unit in the motor drive device according to the first to fourth embodiments of the present disclosure, (A) exemplifying the estimated temperature of the charging resistor, (B) exemplifying the estimated temperature 4 shows an example of setting temperature thresholds used for temperature comparison. FIG. 4 is a diagram illustrating the operation of the opening/closing unit, the pre-charging circuit and the discharging circuit in the motor driving device according to the first embodiment of the present disclosure; 9 is a flow chart showing the operation flow of a pre-charging circuit, a discharging circuit, and an opening/closing unit in a motor drive device according to a second embodiment of the present disclosure; FIG. 7 is a diagram illustrating the operation of the opening/closing unit, the pre-charging circuit and the discharging circuit in the motor driving device according to the second embodiment of the present disclosure; FIG. 3 illustrates a motor drive device according to third and fourth embodiments of the present disclosure; 8 is a flow chart showing the operation flow of a pre-charging circuit, a discharging circuit, an opening/closing unit, and an alarm output unit in a motor drive device according to a third embodiment in which an alarm output unit is further provided in the first embodiment of the present disclosure; 9 is a flow chart showing the operation flow of a pre-charging circuit, a discharging circuit, an opening/closing unit, and an alarm output unit in a motor drive device according to a third embodiment in which an alarm output unit is further provided in the second embodiment of the present disclosure; FIG. 10 is a flow chart showing the operation flow of a pre-charging circuit and an alarm output section in a motor drive device according to a fourth embodiment in which an alarm output section is further provided in the first or second embodiment of the present disclosure; FIG.

A motor drive device having a precharging circuit will be described below with reference to the drawings. In order to facilitate understanding, the scales of these drawings are appropriately changed. The form shown in the drawing is an example of implementation and is not limited to the illustrated embodiment. Further, in the following description, "close", "close operation" and "closed state" are synonymous, and "open", "open operation" and "open state" are synonymous. be.

FIG. 1 is a diagram illustrating a motor drive device according to first and second embodiments of the present disclosure. First, the configuration of the motor drive device 1 according to the first embodiment will be described, but the configuration shown in FIG. 1 can also be applied to a second embodiment described later.

As an example, a case where a motor drive device 1 connected to an AC power supply 2 controls an AC motor (hereinafter simply referred to as "motor") 3 will be shown. In this embodiment, the type of motor 3 is not particularly limited, and may be, for example, an induction motor or a synchronous motor. Also, the number of phases of the AC power supply 2 and the motor 3 is not particularly limited in this embodiment, and may be three-phase or single-phase, for example. In the illustrated example, the AC power supply 2 and the motor 3 each have three phases. Examples of the AC power supply 2 include a three-phase AC 400V power supply, a three-phase AC 200V power supply, a three-phase AC 600V power supply, a single-phase AC 100V power supply, and the like. Machines provided with the motor 3 include, for example, machine tools, robots, forging machines, injection molding machines, industrial machines, various electrical appliances, trains, automobiles, and aircraft.

As shown in FIG. 1, the motor driving device 1 includes a rectifying circuit 11, a capacitor 12, an inverter 13, a pre-charging circuit 14, a discharging circuit 15, a temperature estimating section 16, a control section 17, and an opening/closing section. 19 and a power supply unit 23 for control unit.

In this embodiment, the motor drive device 1 further includes a signal generator 18 that generates an emergency stop signal for stopping the motor 3 and an emergency stop release signal for canceling the emergency stop of the motor 3 . The signal generator 18 may be provided outside the motor drive device 1, or may be provided, for example, in a host controller (not shown) that controls the motor drive device 1 in an integrated manner. Regardless of whether the signal generator 18 is inside or outside the motor drive device 1, the signal generator 18 generates an emergency stop signal and an emergency stop release signal according to, for example, a ladder program, or when an operator operates the motor. It is generated by operating an emergency stop button provided on the driving device 1, the host controller, or the like. The emergency stop signal and the emergency stop cancellation signal generated by the signal generator 18 are input to the controller 17 .

The rectifier circuit 11 is a forward converter that converts AC power input from the AC power supply 2 into DC power and outputs the DC power to a DC link. The rectifier circuit 11 is configured as a three-phase bridge circuit when three-phase AC power is supplied from the AC power supply 2 and configured as a single-phase bridge circuit when single-phase AC power is supplied from the AC power supply 2 . Examples of the rectifier circuit 11 include a diode rectifier circuit, a 120-degree conduction rectifier circuit, and a PWM switching control type rectifier circuit. For example, if the rectifier circuit 11 is a PWM switching control type rectifier circuit, it is composed of a switching element and a bridge circuit of diodes connected in anti-parallel to the switching element. Accordingly, each switching element is on/off controlled to perform power conversion in both the AC and DC directions. Examples of switching elements include IGBTs, FETs, thyristors, GTOs, SiCs, and transistors, but the types of switching elements themselves do not limit the present embodiment, and other switching elements may be used.

A capacitor 12 is provided in a DC link that electrically connects the DC output side of the rectifier circuit 11 and the DC input side of the inverter 13 . The capacitor 12 has a function of accumulating energy (DC power) in the DC link and a function of suppressing pulsation of the DC side output of the rectifier circuit 11 . DC power is stored in the DC link by charging the capacitor 12 . Examples of the capacitor 12 provided in the DC link include, for example, electrolytic capacitors and film capacitors.

The inverter 13 converts the DC power in the DC link into AC power for driving the motor 3 and outputs the AC power. In the illustrated example, the motor 3 is a three-phase AC motor, so the inverter 13 is configured as a three-phase bridge circuit. If the motor 3 is a single-phase motor, the inverter 13 is configured as a single-phase bridge circuit. Examples of the inverter 13 include a PWM inverter including semiconductor switching elements therein. When the inverter 13 is composed of a PWM inverter, it is composed of a semiconductor switching element and a bridge circuit of freewheeling diodes connected in antiparallel thereto. In this case, examples of semiconductor switching elements include IGBTs, FETs, thyristors, GTOs, SiCs, and transistors. There may be.

A preliminary charging circuit (initial charging circuit) 14 is provided for preliminary charging (initial charging) of the capacitor 12 before the motor driving device 1 starts driving the motor 3 . In the example shown in FIG. 1 , the precharge circuit 14 is provided on the AC input side of the rectifier circuit 11 . The precharging circuit 14 has a charging resistor bypass switch 31 and a charging resistor 32 connected in parallel to the charging resistor bypass switch 31 . When charging resistor bypass switch 31 is opened (turned off), charging resistor 32 is included in the current path. When the charging resistor bypass switch 31 is closed (turned on), a current path bypassing the charging resistor 32 (that is, a current path not including the charging resistor 32) is formed. In the example shown in FIG. 1, since the AC power supply 2 is three-phase AC, the charging resistor bypass switch 31 and the charging resistor 32 are provided for each phase. Examples of the charging resistor bypass switch 31 include semiconductor switching elements such as IGBTs, FETs, thyristors, GTOs, SiCs, and transistors, and mechanical switches such as relays. The opening and closing of the charging resistor bypass switch 31 is controlled by the controller 17 .

When the control unit 17 receives the emergency stop cancellation signal from the signal generation unit 18, the control unit 17 controls the preliminary charging circuit 14 to perform the preliminary charging operation, and closes (closes) the opening/closing unit 19. on). During the preliminary charging period, the charging resistor bypass switch 31 receives an open command from the control unit 17 and opens (turns off). During the pre-charging period, the charging resistance bypass switch 31 is kept open, so that the charging resistance 32 is included in the current path, and the AC power from the AC power source 2 passes through the opening/closing part 19 and the charging resistance 32. input to the rectifier circuit 11. The rectifying circuit 11 converts the input AC power into DC power, outputs the DC power to the DC link, and flows into the capacitor 12. The capacitor 12 is charged to a predetermined charging voltage (preliminary charging operation). During the pre-charging period, the current flowing from the AC power supply 2 to the rectifier circuit 11 flows through the charging resistor 32, so generation of rush current can be prevented. When the capacitor 12 is charged up to a predetermined charging voltage, the controller 17 outputs a close command to the charging resistor bypass switch 31, and the charging resistor bypass switch 31 is switched from open to closed to close the charging resistor. A current path bypassing 32 is formed to complete the pre-charging operation by pre-charging circuit 14 . After the preliminary charging operation is completed, the AC power from the AC power supply 2 is input to the rectifier circuit 11 through the open/close portion 19 and the charging resistor bypass switch 31 which are both closed.

A discharge circuit 15 is provided in parallel with the capacitor 12 in the DC link. A discharge operation in which the discharge circuit 15 and the capacitor 12 are electrically connected to discharge DC power in the DC link and a non-discharge operation in which the electrical connection between the discharge circuit 15 and the capacitor 12 is cut are selectively performed. can be switched. Therefore, the discharge circuit 15 has a discharge switch 34 and a discharge resistor 33 connected in series with the discharge switch 34 . In the example shown in FIG. 1, in the discharge circuit 15, the discharge resistor 33 is provided on the high potential side and the discharge switch 34 is provided on the low potential side, but these may be replaced. Examples of the discharge switch 34 include semiconductor switching elements such as IGBTs, FETs, thyristors, GTOs, SiCs, and transistors, and mechanical switches such as relays. In the example shown in FIG. 1, the discharge switch 34 is composed of a semiconductor switching element. The opening and closing of the discharge switch 34 of the discharge circuit 15 is controlled by the controller 17 . When the discharge switch 34 is closed under the control of the control unit 17, the discharge resistor 33 and the capacitor 12 are electrically connected, and the DC power in the DC link flows into the discharge resistor 33 and is consumed as heat (discharge motion). When the discharge switch 34 is opened under the control of the control section 17, the electrical connection between the discharge resistor 33 and the capacitor 12 is cut off, and a non-discharge operation state is entered.

The switching unit 19 has any one of an electromagnetic contactor, a relay, or a semiconductor switching element for closing or opening a current path. In the example shown in FIG. 1 , the pre-charging circuit 14 is provided on the AC input side of the rectifier circuit 11 , so the switching unit 19 is provided between the AC power source 2 and the pre-charging circuit 14 .

The temperature estimator 16 sequentially calculates the estimated temperature of the charging resistor 32 in the precharging circuit 14 . Details of calculation processing of the estimated temperature of the charging resistor 32 by the temperature estimator 16 will be described later.

The control unit 17 controls each operation of the inverter 13 , the preliminary charging circuit 14 , the discharging circuit 15 and the switching unit 19 . The control unit 17 is driven by a control voltage supplied from the control unit power supply unit 23 . In addition to the rectification operation of the rectifier circuit 11, the control power supply 23 rectifies the AC voltage supplied from the AC power supply 2 and steps it down to a control voltage level (eg, 5 [V] or 24 [V]). It supplies the data to the control unit 17 .

The control unit 17 controls driving of the motor 3 by outputting a power conversion command to the inverter 13 and controlling the power conversion operation of the inverter 13 . More details are as follows. The control unit 17 generates a power conversion command based on the rotational speed (of the rotor) of the motor 3, the current flowing through the windings of the motor 3, a predetermined torque command, an operation program of the motor 3, and the like. The inverter 13 outputs AC power for driving the motor 3 according to the power conversion command received from the control unit 17 . The motor 3 is controlled in speed, torque, or rotor position based on, for example, voltage-variable and frequency-variable AC power supplied from the inverter 13 . Therefore, after all, the control of the motor 3 by the control unit 17 is realized by controlling the power conversion operation of the inverter 13 . The control unit 17 controls power conversion in the inverter 13 according to a predetermined operation program, thereby controlling the motor 3 to operate according to a predetermined operation pattern.

Further, the control unit 17 outputs a charging command to the preliminary charging circuit 14 to control the opening/closing operation of the charging resistance bypass switch 31 . More specifically, when the controller 17 receives an emergency stop cancellation signal from the signal generator 18, the controller 17 opens the charging resistor bypass switch 31 and performs a pre-charging operation until the capacitor 12 reaches a predetermined charging voltage, Furthermore, after the capacitor 12 reaches the charging voltage, the precharging circuit 14 is controlled so that the charging resistor bypass switch 31 is closed to complete the precharging operation.

The control unit 17 also outputs a discharge command to the discharge circuit 15 to control the opening/closing operation of the discharge switch 34 . However, when the estimated temperature of the charging resistor 32 calculated by the temperature estimator 16 exceeds a predetermined temperature threshold, the discharging circuit 15 maintains the non-discharging operation, that is, the discharging switch 34 maintains an open state. to control. The details of the control of the discharge circuit 15 by the controller 17 will be described later.

Further, the control section 17 outputs an opening/closing command to the opening/closing section 19 to control the opening/closing operation of the opening/closing section 19 .

The temperature estimation unit 16, the control unit 17, and the signal generation unit 18 described above may be constructed, for example, in the form of software programs, or may be constructed by combining various electronic circuits and software programs. For example, when constructing these in a software program format, by operating an arithmetic processing unit such as an MPU or a DSP in the motor drive device 1 or in the machine provided with the motor drive device 1 according to the software program, the above-mentioned It is possible to realize the function of each part of Alternatively, the temperature estimation unit 16, the control unit 17, and the signal generation unit 18 may be implemented as a semiconductor integrated circuit in which a software program that implements the functions of each unit is written. Alternatively, a software program that implements the functions of the temperature estimation unit 16, the control unit 17, and the signal generation unit 18 may be stored in a storage medium.

In the example shown in FIG. 1, the pre-charging circuit 14 is provided on the AC input side of the rectifier circuit 11, but as an alternative example, the pre-charging circuit 14 may be provided on the DC output side of the rectifying circuit 11. FIG. FIG. 2 is a diagram showing a case where the pre-charging circuit is provided on the DC output side of the rectifier circuit in the motor driving devices according to the first and second embodiments of the present disclosure. Although the configuration of the motor drive device 1 according to the first embodiment will be described with reference to FIG. 2, the configuration shown in FIG. 2 can also be applied to a second embodiment described later.

As shown in FIG. 2, when the pre-charging circuit 14 is provided on the DC output side of the rectifier circuit 11, a pair of charging resistor bypass switch 31 and charging resistor 32 are provided.

In FIG. 2, when the controller 17 receives an emergency stop cancellation signal from the signal generator 18, the controller 17 controls the preliminary charging circuit 14 to perform a preliminary charging operation, Control to close. During the pre-charging period, the charging resistor bypass switch 31 is kept open, so the charging resistor 32 is included in the current path, and the current output from the rectifier circuit 11 passes through the charging resistor 32 as a charging current. It flows into the capacitor 12 and the capacitor 12 is charged up to a predetermined charging voltage (precharging operation). Since the current output from the rectifier circuit 11 flows through the charging resistor 32 during the pre-charging period, it is possible to prevent the occurrence of rush current. When the capacitor 12 is charged up to a predetermined charging voltage, the controller 17 outputs a close command to the charging resistor bypass switch 31, and the charging resistor bypass switch 31 is switched from open to closed to close the charging resistor. A current path bypassing 32 is formed to complete the pre-charging operation by pre-charging circuit 14 . After the preliminary charging operation is completed, the DC power output from the rectifier circuit 11 is input to the inverter 13 (and the capacitor 12) via the charging resistor bypass switch 31. FIG.

Subsequently, a specific example of selective execution of the discharge circuit 15 by the control unit 17 based on the calculation processing of the temperature estimating unit 16 in the motor drive device 1 according to the first and second embodiments of the present disclosure and the calculation result will be described in the prior art. will be described in comparison with the motor drive device of

FIG. 3 is a diagram illustrating the operation of an opening/closing unit, a pre-charging circuit, and a discharging circuit in a conventional motor drive device. Here, as an example, a case where the control unit in the motor drive device receives the emergency stop signal and the emergency stop cancellation signal at the timing shown in FIG. 3 will be described.

During the emergency stop of the motor 3 up to time _t1 , the charging resistor bypass switch in the switching section and the precharging circuit is open, and the discharging circuit and the capacitor are electrically connected. When the control unit in the motor drive device receives the emergency stop cancellation signal at time _t1 , the pre-charging operation by the pre-charging circuit and the non-discharging operation by the discharging circuit are executed under the control of the control unit. That is, during the precharging period from time _t1 to time _t2 , the charging resistor bypass switch in the precharging circuit performs an opening operation, the switch section performs a closing operation, and the electrical connection between the discharge circuit and the capacitor is The connection will be closed. As a result, during the preliminary charging period, charging current flows through the charging resistor to charge the capacitor, and the DC link voltage gradually increases. Note that the charging current flowing through the charging resistor actually shows a tendency to oscillate positively and negatively and attenuate, but is shown by a positive-side envelope in FIG. 3 for the sake of simplicity of explanation. Also, since the charging current flows through the charging resistor, the temperature of the charging resistor gradually rises.

At time _t2 , the capacitor reaches a predetermined charging voltage, so that the charging resistor bypass switch closes under the control of the controller to complete the pre-charging operation. This completes the preparation for motor operation. Since no current flows through the charging resistor after this point, the temperature of the charging resistor changes from rising to falling after a while.

When the control unit in the motor drive device receives the emergency stop signal at time _t3 , the opening operation is performed by the switching unit and the charging resistor bypass switch in the precharging circuit under the control of the control unit, and the discharging circuit and the capacitor are connected. It is electrically connected and a discharge operation is performed by a discharge circuit. As a result, the DC link voltage abruptly drops to 0 [V]. Also, since no current flows through the charging resistor, the temperature of the charging resistor continues to drop.

When the controller in the motor drive device receives the emergency stop cancel signal at time _t4 , the controller performs a closing operation by the opening/closing part and a non-discharge operation by the discharge circuit. That is, during the pre-charging period from time _t4 to time _t5 , the switch closes, the charging resistor bypass switch in the pre-charging circuit continues to open, and the electricity between the discharge circuit and the capacitor connection is terminated. As a result, during the preliminary charging period, charging current flows through the charging resistor to charge the capacitor, and the DC link voltage gradually increases. Also, since the charging current flows through the charging resistor, the temperature of the charging resistor changes from decreasing to increasing.

Here, if the time _t3 at which the controller in the motor drive device receives the emergency stop signal and the time _t4 at which it receives the emergency stop release signal is short, the charging resistance is sufficiently high even at time _t4 . It is not cooled and the temperature of the charging resistor is still high. When the pre-charging operation is started at time _t4 in the state where the temperature of the charging resistor is high in this way, the accumulation of heat in the charging resistor further progresses. As a result, after time _t4 , the temperature of the charging resistor at time _t4 is further superimposed on the temperature of the charging resistor to increase.

At time _t5 , the capacitor reaches the predetermined charging voltage, so that the control section closes the charging resistor bypass switch to complete the pre-charging operation. This completes the preparation for motor operation. Since no current flows through the charging resistor after this point, the temperature of the charging resistor changes from rising to falling after a while. However, since heat was accumulated in the charging resistor in the vicinity of time _t4 before this, the temperature drops from a high temperature. For example, even after time _t6 , when the control section in the motor drive alternately receives the emergency stop signal and the emergency stop cancellation signal for a short period of time, the discharge operation by the discharge circuit and the precharge operation by the precharge circuit are frequently performed. However, the charging resistor cannot be sufficiently cooled, and heat accumulation in the charging resistor further progresses, and the temperature of the charging resistor is superimposed and increased.

As described above, in the conventional motor drive device, when the discharging operation is executed by the discharge circuit in response to the reception of the emergency stop signal, all the power accumulated in the capacitor is discharged and the DC link voltage becomes 0 [V]. . After that, when the emergency stop cancellation signal is immediately received, the precharging operation is performed by the precharging circuit. , so a lot of charging current flows through the charging resistor. As the charging current flowing through the charging resistor increases, the amount of heat accumulated in the charging resistor increases. The charging resistor, which has accumulated a large amount of heat, is already in a high temperature state, and in such a state, when the pre-charging operation is performed by the pre-charging circuit in response to the reception of the emergency stop cancellation signal and charging current further flows, the temperature of the charging resistor rises. is superimposed. When the emergency stop signal and the emergency stop release signal are alternately input in a short period of time, the closing and opening of the charging resistor bypass switch are repeated, and the temperature of the charging resistor continues to rise. The resistance melts, leading to damage to the pre-charging circuit.

Therefore, in the present embodiment, if a certain amount of heat has already been accumulated in the charging resistor 32 when the controller 17 of the motor drive device 1 receives the emergency stop signal, the discharging circuit 15 does not perform the discharging operation. Keep the non-discharge operation running. As a result, the charging current flowing through the charging resistor 32 in the subsequent preliminary charging operation by the preliminary charging circuit 14 is suppressed, and a large temperature rise of the charging resistor 32 is avoided. When the controller 17 of the motor drive device 1 receives the emergency stop signal, the judgment as to whether or not a certain amount of heat is accumulated in the charging resistor 32 is made when the controller 17 of the motor drive device 1 receives the emergency stop signal. is based on whether or not the estimated temperature of the charging resistor 32 calculated by the temperature estimator 16 exceeds a predetermined temperature threshold. More specifically, when the estimated temperature of the charging resistor 32 exceeds the temperature threshold when receiving the emergency stop signal, the control unit 17 controls the discharging circuit 15 to maintain the non-discharging operation. On the other hand, if the estimated temperature of the charging resistor 32 does not exceed the temperature threshold when receiving the emergency stop signal, the control unit 17 controls the discharging circuit 15 to perform the discharging operation. Further, in either case, when the controller 17 receives the emergency stop cancellation signal thereafter, the controller 17 controls the discharge circuit 15 to perform the non-discharge operation. An example of the temperature threshold to be set will be described later.

FIG. 4 is a flow chart showing the operation flow of the pre-charging circuit, the discharging circuit, and the switching unit in the motor driving device according to the first embodiment of the present disclosure.

As described above, in the motor drive device 1, the controller 17 determines whether or not the estimated temperature of the charging resistor 32 calculated by the temperature estimator 16 exceeds the predetermined temperature threshold at the time of receiving the emergency stop cancellation signal. judge. The timing at which the control unit 17 receives the emergency stop cancellation signal is not particularly limited. 17, the estimated temperature of the charging resistor 32 is sequentially calculated at a predetermined cycle. The shorter the calculation cycle of the estimated temperature by the temperature estimator 16 is, the higher the accuracy of the calculated estimated temperature of the charging resistor 32 is. Details of calculation processing of the estimated temperature of the charging resistor 32 by the temperature estimating unit 16 will be described later.

In step S<b>101 , the control unit 17 determines whether or not an emergency stop cancellation signal has been received from the signal generation unit 18 . If it is determined in step S101 that the emergency stop cancellation signal has been received, the process proceeds to step S102.

In step S<b>102 , the control unit 17 controls the charging resistance bypass switch 31 in the precharging circuit 14 to open. As a result, the charging resistor 32 is included in the current path.

In step S103, the control unit 17 controls the opening/closing unit 19 to be closed. As a result, the opening/closing portion 19 maintains its closed state and the charging resistor bypass switch 31 maintains its open state. 11. The rectifier circuit 11 converts the input AC power into DC power and outputs the DC power to the DC link. The current output from the rectifier circuit 11 flows into the capacitor 12 as a charging current, and the capacitor 12 is charged to a predetermined charging voltage (preliminary charging operation). At the start of execution of step S103, the electrical connection between the discharge resistor 33 and the capacitor 12 is disconnected by controlling the control unit 17 to open the discharge switch 34 in the discharge circuit 15. FIG.

In step S104, the control unit 17 determines whether or not the preliminary charging operation by the preliminary charging circuit 14 has been completed. When the voltage of the capacitor 12 (DC link voltage) reaches the predetermined charging voltage, the controller 17 determines that the preliminary charging operation by the preliminary charging circuit 14 is completed, and proceeds to step S105.

In step S105, the control unit 17 controls the charging resistance bypass switch 31 in the precharging circuit 14 to close. As a result, a current path bypassing the charging resistor 32 is formed, and AC power from the AC power supply 2 is input to the rectifier circuit 11 via the open/close portion 19 and the charging resistor bypass switch 31 which are both closed. The rectifier circuit 11 converts the input AC power into DC power and outputs it to the DC link, and the inverter 13 converts the DC power in the DC link into AC power and supplies it to the motor 3 .

In step S106, the control unit 17 generates a power conversion command based on the rotational speed of the motor 3, the current flowing through the windings of the motor 3, a predetermined torque command, the operation program of the motor 3, and the like. The inverter 13 converts the DC power in the DC link into AC power according to the power conversion command received from the control unit 17 and supplies the AC power to the motor 3 . Motor 3 is driven based on AC power supplied from inverter 13 .

In step S<b>107 , the controller 17 determines whether or not an emergency stop signal has been received from the signal generator 18 . If it is determined in step S107 that an emergency stop signal has been received, the process proceeds to step S108, and the control unit 17 adds the estimated temperature of the charging resistor 32 calculated by the temperature estimating unit 16 at that time to the temperature estimating unit 16 Get from

In step S108, the control section 17 controls the opening/closing section 19 to be opened.

In step S<b>109 , the control unit 17 controls the charging resistor bypass switch 31 in the precharging circuit 14 to open. Since the opening/closing portion 19 is open, the motor drive device 1 is electrically disconnected from the AC power source 2, and the AC power from the AC power source 2 is supplied to the motor drive device 1 via the charging resistor 32. it doesn't flow in.

In step S110, the controller 17 estimates the charging resistor 32 calculated by the temperature estimator 16 at the time when the emergency stop signal is received (that is, when the controller 17 determines that the emergency stop signal is received in step S107). A determination is made as to whether the temperature exceeds a predetermined temperature threshold. In step S110, when it is determined that the estimated temperature of the charging resistor 32 exceeds the temperature threshold, the process proceeds to step S111, and when it is determined that the estimated temperature of the charging resistor 32 does not exceed the temperature threshold, the process proceeds to step S112. .

When it is determined in step S110 that the estimated temperature of the charging resistor 32 exceeds the temperature threshold, the control section 17 controls the discharge circuit 15 to maintain the non-discharge operation in step S111. More specifically, the control unit 17 disconnects the electrical connection between the discharge resistor 33 and the capacitor 12 by controlling the discharge switch 34 in the discharge circuit 15 to be kept open, thereby bringing the non-discharge operation state into effect. maintain. As a result, the DC power in the DC link (that is, the DC power accumulated in the capacitor 12) does not flow into the discharge resistor 33. At the start of execution of step S102, the control unit 17 controls the discharge switch 34 in the discharge circuit 15 to open, so that the discharge circuit of the control unit 17 in step S111 is already in the non-discharge operation state. Control over 15 does not change this non-discharging operating state. Therefore, the DC link voltage does not drop abruptly.

After execution of step S111, the process returns to step S101. Immediately after the execution of step S111, even if it is determined in step S101 that an emergency stop cancellation signal has been received and the pre-charging operation of steps S103 and S104 is executed, the DC link voltage does not drop significantly (that is, 0 [V] ), the current flowing through the charging resistor 32 is very small, the heat accumulation in the charging resistor 32 is small, and a rapid temperature rise of the charging resistor 32 can be avoided.

On the other hand, if it is determined in step S110 that the estimated temperature of the charging resistor 32 does not exceed the temperature threshold, then in step S112 the control unit 17 controls the discharging circuit 15 to perform the discharging operation. More specifically, the controller 17 electrically connects the discharge resistor 33 and the capacitor 12 by controlling the discharge switch 34 in the discharge circuit 15 to be closed. As a result, the non-discharging operation state of the discharge circuit 15 continued from step S102 is switched to the discharging operation state, and the DC power in the DC link (that is, the DC power accumulated in the capacitor 12) flows into the discharge resistor 33. It is consumed as heat, and the DC link voltage abruptly drops to 0 [V].

Step S112 is executed when it is determined in step S110 that the estimated temperature of the charging resistor 32 does not exceed the temperature threshold. . After execution of step S112, the process returns to step S101. Immediately after the execution of step S112, even if it is determined in step S101 that an emergency stop cancellation signal has been received and the preliminary charging operation of steps S103 and S104 is executed, and a large amount of charging current flows through the charging resistor 32, Since the heat accumulation in the charging resistor 32 is slight, it does not reach a temperature that causes the charging resistor 32 to melt.

Next, details of calculation processing of the estimated temperature of the charging resistor 32 by the temperature estimator 16 will be described.

FIG. 5 is a diagram for explaining the estimated temperature calculation process by the temperature estimator in the motor drive device according to the first to fourth embodiments of the present disclosure, (A) exemplifies the estimated temperature of the charging resistor, ( B) shows an example of setting a temperature threshold used for comparison of estimated temperatures.

For example, at the stage of designing the motor driving device 1, the motor driving device 1 connected to the precharging circuit 14 is pre-charged by experiment, and various parameters necessary for calculating the estimated temperature of the charging resistor 32 are acquired. Then, using the acquired parameters, a calculation formula used for the estimated temperature calculation process is defined on the software program. The software program created in this manner is installed in an arithmetic processing unit that implements the function of the temperature estimation unit 16 . The estimated temperature of the charging resistor 32 is calculated by the arithmetic processing unit operating according to this software program.

Due to one pre-charging operation, the estimated temperature of the charging resistor 32 changes as illustrated in FIG. 5(A). Until time _t11 when the pre-charging operation is started, the opening/closing portion 19 and the charging resistance bypass switch 31 in the pre-charging circuit 14 are open. At time _t11 , under the control of the control unit 17 in the motor drive device 1, the charging resistance bypass switch 31 executes the opening operation, the opening/closing unit 19 executes the closing operation, and the preliminary charging operation by the preliminary charging circuit 14 is started. Then, since the charging resistor 32 is included in the current path, the charging current flows through the charging resistor 32, and the temperature of the charging resistor 32 gradually rises with a certain thermal time constant. At time _t12 , the capacitor 12 reaches a predetermined charging voltage, so that the control unit 17 controls the charging resistor bypass switch 31 to close and complete the precharging operation. After time _t12 , a current path bypassing the charging resistor 32 is formed, so no current flows through the charging resistor 32, but the temperature of the charging resistor 32 rises for a while, and at time _t13 , the temperature of the charging resistor 32 reaches turn to decline.

The time during which the temperature rise of the charging resistor 32 continues from the start of the preliminary charging operation at time _t11 to time _t13 , which is a short time after the completion of the preliminary charging operation, is referred to as "temperature rise duration U". That is, the temperature rise duration time U is defined as "the time during which the temperature rise of the charging resistor 32 continues due to one precharging operation".

In this embodiment, as an example, it is stipulated that the estimated temperature T _up of the charging resistor 32 during the period of temperature rise duration U changes according to Equation 1 below.

The temperature of the charging resistor 32 decreases during a period other than the temperature rise duration U. In this embodiment, as an example, the estimated temperature T _down of the charging resistor 32 during a period other than the temperature rise duration U is as follows. It is defined that it transitions according to Equation 2.

In equations 1 and 2, T _rise indicates a temperature rise value defined as the maximum value of the charging resistor 32 that rises in one precharging operation, τ is a thermal time constant of the charging resistor 32, and T ₀ is the estimated temperature of the charging resistor 32 at the start of the preliminary charging operation, and T _air is the temperature of the environment in which the motor drive device 1 is installed. Among these parameters, the temperature rise value T _rise , the thermal time constant τ, and the temperature rise duration U were obtained in advance by performing a pre-charging operation in the motor driving device 1 connected to the pre-charging circuit 14 through experiments. Keep Then, the software program that implements the function of the temperature estimator 16 defines Equations 1 and 2 using the acquired parameters. Further, in this software program, the estimated temperature is calculated according to Equation 1 from the time when the control unit 17 receives the emergency stop cancellation signal from the signal generation unit 18 until the temperature rise duration time U elapses. is defined so that the estimated temperature is calculated according to Equation 2. Further, for the estimated temperature of the charging resistor 32 at the start of the preliminary charging operation in Equation 1, the temperature T _air of the environment in which the motor drive device 1 is installed is set as the initial value _T0 . It is specified that the estimated temperature calculated immediately before the start of the charging operation is set. The software program created in this manner is installed in an arithmetic processing unit that implements the function of the temperature estimation unit 16 . Note that the parameters obtained by the experiment are stored in a nonvolatile memory (not shown), and the parameters are called from the nonvolatile memory when the software program related to the temperature estimation unit 16 is run. may

As described above, the temperature T _air of the environment in which the motor driving device 1 is installed is set as the initial value T ₀ of the estimated temperature. In that case, the temperature (estimated temperature) of the charging resistor 32 may be higher than the conventional temperature T _air . Therefore, the time of the real-time clock and the estimated temperature (that _is , T _up or T _down ) are recorded in a non-volatile memory. The estimated temperature at the current time is obtained by substituting the elapsed time from the last time the estimated temperature was recorded in the non-volatile memory to the current _time . may be used.

The temperature rise value T _rise , the thermal time constant τ, and the temperature rise duration U changes. Therefore, the relationship between various voltages on the AC power supply 2 side of the charging resistor 32 and these parameters is defined in a software program, and input to the motor driving device 1 when the motor driving device 1 is actually operated. The temperature rise value T _rise , the thermal time constant τ, and the temperature rise duration U corresponding to the AC voltage may be selected to execute the estimated temperature calculation process by the temperature estimator 16 . In this case, first, by experiment, in the motor driving device 1 connected to the preliminary charging circuit 14, the preliminary charging operation was performed under various voltages on the AC power supply 2 side of the charging resistor 32, and each voltage and the temperature rise value T A table showing the relationship between _rise , thermal time constant τ, and temperature rise duration U is obtained in advance. This table is defined in the software program that implements the function of the temperature estimating unit 16, and the temperature rise corresponding to the AC voltage input to the motor driving device 1 when the motor driving device 1 is actually operated. The software program may be defined such that the value T _rise , the thermal time constant τ and the temperature rise duration U are selected from a table. By using such a software program, the temperature estimator 16 can calculate a highly accurate estimated temperature.

During actual operation of the motor drive device 1 , the temperature estimator 16 sequentially calculates the estimated temperature of the charging resistor 32 according to Equations 1 and 2. The temperature T _air of the environment in which the motor driving device 1 is installed in Equation 2 may be measured by a thermometer placed near the motor driving device 1, or may be already built into the motor driving device 1. Alternatively, a predetermined constant temperature (constant) close to the actual temperature of the environment in which the motor drive device 1 is installed may be used. The temperature estimating unit 16 calculates the estimated temperature T _up of the charging resistor 32 according to Equation 1 from the time when the control unit 17 receives the emergency stop cancellation signal from the signal generating unit 18 until the temperature rise duration time U elapses. , the temperature estimator 16 calculates the estimated temperature T _down of the charging resistor 32 according to the equation (2) at other times. If the time at which the control unit 17 receives the emergency stop signal is included in the period of the temperature rise duration U, the estimated temperature T _up of the charging resistor 32 calculated by the temperature estimating unit 16 according to Equation 1 is compared with the temperature threshold. used for On the other hand, if the time at which the control unit 17 receives the emergency stop signal is included in a period other than the temperature rise duration U, the estimated temperature T _down of the charging resistor 32 calculated by the temperature estimating unit 16 according to Equation 2 is the temperature threshold. used for comparison with

As shown in FIG. 5B, the temperature threshold may be set to a value obtained by subtracting the temperature rise value T _rise of the charging resistor 32 obtained by experiment from the maximum temperature rating of the charging resistor 32, for example. Furthermore, if the temperature threshold is set to a value obtained by subtracting the temperature rise value T _rise of the charging resistor 32 and the margin from the maximum temperature rating of the charging resistor 32, damage due to heat generation can be more reliably avoided. . For the maximum temperature rating of the charging resistor 32, for example, a value in a standard table that defines the specification data of the charging resistor 32 may be used.

Formulas 1 and 2 are examples, and the estimated temperature of charging resistor 32 may be calculated based on other calculation formulas.

Further, in the example shown in FIG. 1, since the preliminary charging circuit 14 is provided on the AC input side of the rectifier circuit 11, the charging resistor 32 is provided for each phase of the three-phase AC. corresponds to the estimated temperature of the charging resistor 32 for one phase. When the pre-charging circuit 14 is provided on the DC output side of the rectifier circuit 11 as shown in FIG. 2, only one charging resistor 32 is provided. Corresponds to the estimated temperature.

FIG. 6 is a diagram illustrating the operation of the opening/closing unit, the pre-charging circuit and the discharging circuit in the motor driving device according to the first embodiment of the present disclosure. Here, as an example, the control unit 17 in the motor drive device 1 receives the emergency stop signal at times _t3 and _t5 , receives the emergency stop cancellation signal at times _t1 and _t4 , and particularly receives the emergency stop cancel signal at time _t3. A case in which the estimated temperature of the charging resistor 32 exceeds the temperature threshold when the emergency stop signal is received will be described.

During the emergency stop of the motor 3 until time _t1 , the switch 19 and the charging resistor bypass switch 31 in the precharging circuit 14 are open, and the discharging circuit 15 and the capacitor 12 are electrically connected. there is

When the controller 17 in the motor drive device 1 receives the emergency stop cancellation signal from the signal generator 18 at time t ₁ , the controller 17 controls the preliminary charging circuit 14 to perform the preliminary charging operation and the discharging circuit 15 to perform the non-discharging operation. is executed. That is, during the preliminary charging period from time _t1 to time _t2 , the charging resistance bypass switch 31 in the preliminary charging circuit 14 performs an opening operation, the opening/closing section 19 performs a closing operation, and the discharge circuit 15 and the capacitor 12 is cut off. As a result, during the preliminary charging period, charging current flows through the charging resistor 32 to charge the capacitor 12 and the DC link voltage gradually increases. Note that the charging current flowing through the charging resistor 32 actually exhibits a tendency to oscillate positively and negatively, but is shown by a positive envelope in FIG. 6 for the sake of simplicity. Also, since the charging current flows through the charging resistor 32, the temperature of the charging resistor 32 gradually rises.

At time t ₂ , the capacitor 12 reaches a predetermined charging voltage, so the control unit 17 controls the charging resistance bypass switch 31 to close and complete the precharging operation. Thus, preparation for operation of the motor 3 is completed. After that, no current flows through the charging resistor 32, so the temperature of the charging resistor 32 changes from an increase to a decrease after a while.

When the controller 17 in the motor drive device 1 receives the emergency stop signal at time _t3 , the controller 17 converts the estimated temperature of the charging resistor 32 calculated by the temperature estimator 16 at time _t3 into a temperature estimation Acquired from the unit 16 . In the example shown in FIG. 6, it is determined that the estimated temperature of the charging resistor 32 calculated by the temperature estimating unit 16 exceeds the temperature threshold at time t ₃ . The non-discharging operation in which the electrical connection between the capacitor 12 and the capacitor 12 is cut is maintained, and the opening operation is performed for the opening/closing portion 19 and the charging resistance bypass switch 31 . At time t ₁ , the control unit 17 controls the discharge switch 34 in the discharge circuit ₁₅ to open, so that the non-discharge operation state is already established. Control over the discharge circuit 15 does not change this non-discharge operating state. Therefore, the DC link voltage does not drop abruptly.

When the controller 17 in the motor drive device 1 receives the emergency stop cancellation signal from the signal generator 18 at time t ₄ , the controller 17 controls the opening/closing part 19 to close. At this time, since the charging resistor bypass switch 31 is open, current flows through the charging resistor 32 . However, since the discharge circuit 15 is performing the non-discharge operation, the DC link voltage does not drop significantly (it does not reach 0 [V]), so the charging current flowing through the charging resistor 32 is very small. Therefore, the heat accumulation in the charging resistor 32 is small, and the temperature of the charging resistor 32 does not rise sharply.

At time t ₅ , the capacitor 12 reaches a predetermined charging voltage, so the control unit 17 controls the charging resistance bypass switch 31 to close and complete the precharging operation. Thus, preparation for operation of the motor 3 is completed. Since no current flows through the charging resistor 32 thereafter, the temperature of the charging resistor 32 further drops. As described above, in the motor drive device 1 according to the first embodiment of the present disclosure, the estimated temperature of the charging resistor 32 exceeds the temperature threshold when the control unit 17 receives the emergency stop signal. maintains the execution of the non-discharging operation without executing the discharging operation, and suppresses the charging current flowing through the charging resistor 32 in the subsequent preliminary charging operation by the preliminary charging circuit 14, so that the temperature rise of the charging resistor 32 is suppressed. can be avoided.

Next, a motor drive device according to a second embodiment of the present disclosure will be described. In the second embodiment, the operating contents of the pre-charging circuit are changed according to whether or not the voltage of the DC link exceeds a predetermined voltage threshold when the control unit of the motor drive device receives the emergency stop release signal. This point is different from the first embodiment.

As shown in FIG. 1 or 2, the configuration of a motor drive device 1 according to the second embodiment of the present disclosure is the same as that of the first embodiment. However, in the second embodiment of the present disclosure, the contents of operation when the control unit 17 receives the emergency stop cancellation signal from the signal generation unit 18 are different from those in the first embodiment. More details are as follows.

The control unit 17 controls the pre-charging circuit 14 to open the charging resistor bypass switch 31 if the DC link voltage does not exceed a predetermined voltage threshold when the emergency stop cancellation signal is received from the signal generation unit 18 . do. Further, when the control unit 17 receives the emergency stop cancellation signal from the signal generation unit 18 and the voltage of the DC link exceeds the voltage threshold, the control unit 17 controls the preliminary charging circuit to keep the charging resistor bypass switch 31 closed. 14. The DC link voltage is detected by a voltage detector (not shown in FIGS. 1 and 2) that detects the voltage applied across the positive and negative electrodes of capacitor 12 .

In the already described first embodiment, when the estimated temperature of the charging resistor 32 exceeds the temperature threshold when the controller 17 receives the emergency stop signal at time _t3 as shown in FIG. maintains the non-discharging operation in which the electrical connection between the discharging circuit 15 and the capacitor 12 is disconnected, and the opening operation is executed for the opening/closing portion 19 and the charging resistor bypass switch 31, and then , when the control unit 17 receives the emergency stop cancellation signal from the signal generation unit 18 at time t ₄ , the opening/closing unit 19 performs the closing operation under the control of the control unit 17 . At this time, since the charging resistor bypass switch 31 is closed, current flows through the charging resistor 32 . As shown in FIG. 6, in the first embodiment, the discharge circuit 15 is in the non-discharge operation state at time _t4 , so the voltage of the capacitor 12 should not have decreased. However, there is also the possibility that the voltage of the capacitor 12 has dropped significantly due to natural discharge of the capacitor 12 . In this case, a large inrush current is generated in the charging resistor 32, and there is a possibility that the diode in the rectifier circuit 11 and the capacitor 12 may be destroyed.

Therefore, in the second embodiment, when the control unit 17 receives the emergency stop cancellation signal, it is determined whether or not the voltage of the capacitor 12 has significantly decreased due to natural discharge. The determination of whether or not the voltage of the capacitor 12 has dropped significantly due to natural discharge is made by checking the voltage of the DC link (that is, between the positive and negative electrodes of the capacitor 12) at the time when the control unit 17 of the motor drive device 1 receives the emergency stop cancellation signal. is determined based on whether or not the voltage of the rectifier circuit 11 exceeds a predetermined voltage threshold, for example, the inrush current generated by the voltage drop in the capacitor 12 will destroy the diode and the capacitor 12 in the rectifier circuit 11. If the controller 17 determines that the voltage of the DC link does not exceed the voltage threshold, the voltage of the capacitor 12 drops significantly due to natural discharge. Therefore, the precharging circuit 14 is controlled to open the charging resistor bypass switch 31 to perform a precharging operation. The preliminary charging operation is completed by controlling the preliminary charging circuit 14 to close 31. As a result, in the preliminary charging operation to be executed when the controller 17 further receives the emergency stop cancellation signal next time. It is possible to suppress the current flowing through the charging resistor 32. Thus, according to the second embodiment, it is possible to more reliably prevent the destruction of the charging resistor 32 due to melting and the destruction of the diode and the capacitor 12 in the rectifier circuit 11. can be done.

FIG. 7 is a flow chart showing the operation flow of the pre-charging circuit, the discharging circuit, and the switching unit in the motor driving device according to the second embodiment of the present disclosure.

In the second embodiment, as in the first embodiment, in the motor driving device 1, the estimated temperature of the charging resistor 32 calculated by the temperature estimating unit 16 at the time when the control unit 17 receives the emergency stop cancellation signal reaches a predetermined temperature. It is determined whether or not the temperature threshold of is exceeded. The timing at which the control unit 17 receives the emergency stop cancellation signal is not particularly limited. 17, the estimated temperature of the charging resistor 32 is sequentially calculated at a predetermined cycle.

In step S<b>201 , the control unit 17 determines whether or not an emergency stop cancellation signal has been received from the signal generation unit 18 . If it is determined in step S201 that the emergency stop cancellation signal has been received, the process proceeds to step S202.

In step S202, the control unit 17 determines that the voltage of the DC link at the time of receiving the emergency stop cancellation signal (that is, the time at which the control unit 17 determines that the emergency stop cancellation signal has been received in step S201) exceeds the predetermined voltage threshold. Determine whether or not it exceeds If it is determined in step S202 that the DC link voltage exceeds the voltage threshold, the process proceeds to step S204, and if it is determined that the DC link voltage does not exceed the voltage threshold, the process proceeds to step S203.

When it is determined in step S202 that the DC link voltage does not exceed the voltage threshold, in step S203, the control unit 17 controls the charging resistance bypass switch 31 in the preliminary charging circuit 14 to be opened, and then The process proceeds to step S204.

On the other hand, if it is determined in step S202 that the voltage of the DC link exceeds the voltage threshold, the charging resistance bypass switch 31 of the preliminary charging circuit 14 remains closed and the process proceeds to step S204.

In step S204, the control unit 17 controls the opening/closing unit 19 to be closed. If it is determined in previous step S202 that the voltage of the DC link does not exceed the voltage threshold, a pre-charging operation via charging resistor 32 is performed. That is, since the charging resistor bypass switch 31 in the precharging circuit 14 is in an open state, the charging resistor 32 is included in the current path, and the AC power from the AC power source 2 passes through the opening/closing portion 19 and the charging resistor 32. input to the rectifier circuit 11 via the The rectifier circuit 11 converts the input AC power into DC power and outputs the DC power to the DC link. The current output from the rectifier circuit 11 flows into the capacitor 12 as a charging current, and the capacitor 12 is charged to a predetermined charging voltage (preliminary charging operation via the charging resistor 32).

On the other hand, if it is determined in step S202 that the DC link voltage exceeds the voltage threshold, a pre-charging operation that does not involve the charging resistor 32 is performed. That is, since the charging resistor bypass switch 31 of the preliminary charging circuit 14 is kept closed, a current path bypassing the charging resistor 32 is formed, and the AC power from the AC power supply 2 does not flow through the charging resistor 32. , the opening/closing portion 19 and the charging resistor bypass switch 31 to be input to the rectifying circuit 11 . The rectifier circuit 11 converts the input AC power into DC power and outputs the DC power to the DC link. The current output from the rectifier circuit 11 flows into the capacitor 12 as a charging current, and the capacitor 12 is charged until it reaches a predetermined charging voltage (preliminary charging operation not via the charging resistor 32).

It should be noted that in both the case where the preliminary charging operation is performed via the charging resistor 32 and the case where the preliminary charging operation is not performed via the charging resistor 32, at the start of the execution of step S204, the control unit 17 is in the discharge circuit 15. Electrical connection between the discharge resistor 33 and the capacitor 12 is cut off by controlling the discharge switch 34 to be opened.

In step S205, the control unit 17 determines whether or not the preliminary charging operation by the preliminary charging circuit 14 has been completed. When the voltage of capacitor 12 (DC link voltage) reaches the predetermined charging voltage, control unit 17 determines that the preliminary charging operation by preliminary charging circuit 14 has been completed, and proceeds to step S206.

In step S206, the controller 17 determines whether or not the charging resistor bypass switch 31 of the preliminary charging circuit 14 is open. If it is determined in step S206 that the charging resistor bypass switch 31 is open, the process proceeds to step S207. ), the process proceeds to step S208.

If it is determined in step S206 that the charging resistor bypass switch 31 is open, the controller 17 controls the charging resistor bypass switch 31 in the pre-charging circuit 14 to close in step S207. If it is determined in the previous step S202 that the DC link voltage does not exceed the voltage threshold, the charging resistor bypass switch 31 is opened and the preliminary charging operation is performed via the charging resistor 32, the process of step S207 is performed. After the pre-charging operation is completed, the charging resistor bypass switch 31 is closed to form a current path bypassing the charging resistor 32, and the AC power from the AC power source 2 is supplied to the open/closed parts which are both in the closed state. 19 and the charging resistor bypass switch 31 to the rectifier circuit 11 . After that, the process proceeds to step S208.

If it is not determined in step S206 that the charging resistance bypass switch 31 is open, the charging resistance bypass switch 31 of the preliminary charging circuit 14 remains closed and the process proceeds to step S208. In this case as well, the AC power from the AC power supply 2 is input to the rectifier circuit 11 via the opening/closing portion 19 and the charging resistor bypass switch 31 which are both closed.

The rectifying circuit 11 converts AC power input via the opening/closing unit 19 and the charging resistor bypass switch 31 both of which are closed into DC power and outputs the DC power to the DC link, and the inverter 13 converts the DC power to the DC link. The power is converted into AC power and supplied to the motor 3 . In step S208, the control unit 17 generates a power conversion command based on the rotation speed of the motor 3, the current flowing through the windings of the motor 3, a predetermined torque command, the operation program of the motor 3, and the like. The inverter 13 converts the DC power in the DC link into AC power according to the power conversion command received from the control unit 17 and supplies the AC power to the motor 3 . Motor 3 is driven based on AC power supplied from inverter 13 .

In step S<b>209 , the control unit 17 determines whether or not an emergency stop signal has been received from the signal generation unit 18 .

If it is determined in step S209 that an emergency stop signal has been received, the process proceeds to step S210, and the control unit 17 adds the estimated temperature of the charging resistor 32 calculated by the temperature estimating unit 16 at that time to the temperature estimating unit 16 Get from

In step S210, the control section 17 controls the opening/closing section 19 to be opened.

In step S211, the controller 17 estimates the charging resistance 32 calculated by the temperature estimator 16 at the time when the emergency stop signal is received (that is, when the controller 17 determines that the emergency stop signal has been received in step S209). A determination is made as to whether the temperature exceeds a predetermined temperature threshold. If it is determined in step S211 that the estimated temperature of the charging resistor 32 has exceeded the temperature threshold, the process proceeds to step S212, and if it is determined that the estimated temperature of the charging resistor 32 has not exceeded the temperature threshold, the process proceeds to step S213.

When it is determined in step S211 that the estimated temperature of the charging resistor 32 exceeds the temperature threshold, the control unit 17 controls the discharging circuit 15 to maintain the non-discharging operation in step S212. More specifically, the control unit 17 disconnects the electrical connection between the discharge resistor 33 and the capacitor 12 by controlling the discharge switch 34 in the discharge circuit 15 to be kept open, thereby bringing the non-discharge operation state into effect. maintain. The non-discharging operation by the discharging circuit 15 in step S212 is always executed regardless of the operation contents of the precharging circuit 14 as long as it is determined in step S210 that the estimated temperature of the charging resistor 32 exceeds the temperature threshold. After executing step S212, the process returns to step S201.

On the other hand, if it is determined in step S211 that the estimated temperature of the charging resistor 32 does not exceed the temperature threshold, then in step S213 the control unit 17 controls the discharging circuit 15 to perform the discharging operation. As a result, the non-discharging operation state of the discharge circuit 15 continued from step S202 is switched to the discharging operation state, and the DC power in the DC link (that is, the DC power accumulated in the capacitor 12) flows into the discharge resistor 33. It is consumed as heat, and the DC link voltage abruptly drops to 0 [V]. After execution of step S213, the process returns to step S201.

FIG. 8 is a diagram illustrating the operation of the opening/closing unit, the pre-charging circuit and the discharging circuit in the motor driving device according to the second embodiment of the present disclosure. Here, as an example, the control unit 17 in the motor drive device 1 receives the emergency stop signal at times _t3 and _t5 , receives the emergency stop cancellation signal at times _t1 and _t4 , and particularly receives the emergency stop cancel signal at time _t3. A case in which the estimated temperature of the charging resistor 32 exceeds the temperature threshold when an emergency stop signal is received will be described.

During the emergency stop of the motor 3 until time _t1 , the switch 19 and the charging resistor bypass switch 31 in the precharging circuit 14 are open, and the discharging circuit 15 and the capacitor 12 are electrically connected. there is

When the controller 17 in the motor drive device ₁ receives the emergency stop cancellation signal from the signal generator 18 at time t1, the controller 17 detects that the voltage of the DC link at the time _t1 when the emergency stop cancellation signal is received is Determine whether the voltage threshold is exceeded. In the example shown in FIG. 8, the voltage of the DC link is 0 [V] at time t ₁ and does not exceed the voltage threshold. control to Further, under the control of the control unit 17, the discharging circuit 15 performs non-discharging operation. That is, during the preliminary charging period from time t ₁ to time t ₂ , the switching unit 19 closes, the charging resistor bypass switch 31 in the preliminary charging circuit 14 opens, and the discharge circuit 15 and capacitor 12 is cut off. As a result, during the preliminary charging period, charging current flows through the charging resistor 32 to charge the capacitor 12 and the DC link voltage gradually increases. Note that the charging current flowing through the charging resistor 32 actually exhibits a tendency to oscillate positively and negatively, but is shown by a positive-side envelope in FIG. 8 for the sake of simplicity. Also, since the charging current flows through the charging resistor 32, the temperature of the charging resistor 32 gradually rises.

At time t ₂ , the capacitor 12 reaches a predetermined charging voltage, so the control unit 17 controls the charging resistance bypass switch 31 to close and complete the precharging operation. Thus, preparation for operation of the motor 3 is completed. After that, no current flows through the charging resistor 32, so the temperature of the charging resistor 32 changes from an increase to a decrease after a while.

When the controller 17 in the motor drive device ₁ receives the emergency stop signal at time t3, the controller 17 sends the estimated temperature of the charging resistor 32 calculated by the temperature estimator 16 at time _t3 to the temperature estimator. 16. In the example shown in FIG. 8, it is determined that the estimated temperature of the charging resistor 32 calculated by the temperature estimating unit 16 exceeds the temperature threshold at time t ₃ , so the control unit 17 controls the discharging circuit The non-discharging operation in which the electrical connection between 15 and capacitor 12 is disconnected is maintained, charging resistor bypass switch 31 is maintained closed, and opening/closing unit 19 is opened. Since the charging resistor bypass switch 31 is already closed by controlling the charging resistor bypass switch 31 to be closed at the time _t2 by the control unit 17, the control unit 17 is closed at the time _t3. Control over precharge circuit 14 does not alter the closing action of charge resistor bypass switch 31 . At time t ₁ , the controller 17 controls the discharge switch 34 in the discharge circuit 15 to open, so that the discharge circuit ₁₅ is already in the non-discharge operation state. Control over the discharge circuit 15 does not change this non-discharge operating state. Therefore, the DC link voltage does not drop abruptly.

When the controller 17 in the motor drive device 1 receives the emergency stop cancellation signal from the signal generator 18 at time _t4 , the controller 17 detects that the voltage of the DC link at time _t1 when the emergency stop cancellation signal is received is Determine whether the voltage threshold is exceeded. In the example shown in FIG. 8, at time _t3 , the voltage of the DC link is close to the fully charged voltage and therefore exceeds the voltage threshold. It controls to keep the switch 31 closed. Further, under the control of the control unit 17, the closing operation of the opening/closing unit 19 is executed. Since the charging resistor bypass switch 31 is kept closed in this manner, no current flows through the charging resistor 32 . Therefore, little heat is accumulated in the charging resistor 32, and the temperature of the charging resistor 32 further decreases.

At time _t5 , capacitor 12 reaches the predetermined charging voltage, thus completing the precharge operation. Since the charging resistance bypass switch 31 has already closed, there is no change in the operation of the preliminary charging circuit 14 when the preliminary charging operation is completed. Thus, preparation for operation of the motor 3 is completed. Since no current flows through the charging resistor 32 after this, the temperature of the charging resistor 32 further decreases. As described above, in the motor drive device 1 according to the second embodiment of the present disclosure, when the control unit 17 receives the emergency stop cancellation signal, the voltage of the DC link exceeds the voltage threshold and the estimated temperature of the charging resistor 32 is above the temperature threshold, charging resistor bypass switch 31 continues to perform a closing operation and discharge circuit 15 does not perform a discharging operation (i.e., maintains a non-discharging operation), so next Since no current flows through the charging resistor 32 during the pre-charging operation by the pre-charging circuit 14, even if the capacitor 12 naturally discharges, the temperature rise of the charging resistor 32 can be avoided.

Subsequently, motor drive devices according to third and fourth embodiments of the present disclosure will be described. In the third and fourth embodiments, in the above-described first and second embodiments, an alarm output unit that outputs an alarm for alerting the operator that the temperature of the charging resistor is high is further added. Be prepared.

First, a motor drive device according to a third embodiment of the present disclosure will be described with reference to FIGS. 9 to 11. FIG. In the third embodiment, in the above-described first and second embodiments, an alarm is generated when the estimated temperature exceeds the temperature threshold when an emergency stop cancellation signal for canceling the emergency stop of the motor is received. It further comprises an alarm output unit for outputting.

FIG. 9 is a diagram illustrating a motor drive device according to third and fourth embodiments of the present disclosure; The configuration shown in FIG. 9 can also be applied to a fourth embodiment, which will be described later.

As shown in FIG. 9, the motor drive device 1 according to the third embodiment outputs an alarm when the estimated temperature of the charging resistor 32 exceeds the temperature threshold when the controller 17 receives the emergency stop cancellation signal. Further, an alarm output unit 21 is provided. If it is determined that the estimated temperature of the charging resistor 32 exceeds the temperature threshold when the controller 17 receives the emergency stop cancellation signal, the discharging circuit 15 performs the non-discharging operation instead of the discharging operation. Since the state in which electric charge is accumulated is maintained, the worker may be electrocuted. Therefore, the alarm output unit 21 outputs an alarm to alert the worker. For example, an alarm output from the alarm output unit 21 is used to notify the operator that the discharge circuit 15 is in the non-discharge operation state, so that electric charge is accumulated in the capacitor 12 and there is a risk of electric shock. (not shown) may be provided. Examples of means of the notification unit include a display attached to the motor drive device 1 and its host control device, a display such as a personal computer, a portable terminal, and a touch panel. Further, for example, the notification unit may be realized by an acoustic device that emits sound such as voice, speaker, buzzer, chime, or the like. Alternatively, it may be printed out and displayed on a sheet of paper using a printer. Alternatively, it may be realized by appropriately combining these.

The alarm output unit 21 may be constructed, for example, in the form of a software program, or may be constructed by combining various electronic circuits and software programs. For example, when constructing these in a software program format, an arithmetic processing unit such as an MPU or DSP in the motor drive device 1 or in the machine provided with the motor drive device 1 is operated according to this software program to generate an alarm The function of the output unit 21 can be realized. Alternatively, it may be realized as a semiconductor integrated circuit in which a software program for realizing the function of the alarm output section 21 is written. Alternatively, a software program that implements the function of the alarm output unit 21 may be stored in a storage medium. Circuit components other than the alarm output unit 21 are the same as the circuit components shown in FIG. 1 or FIG. Description is omitted.

FIG. 10 is a flowchart showing the operation flow of the pre-charging circuit, the discharging circuit, the opening/closing unit, and the alarm output unit in the motor drive device according to the third embodiment in which the alarm output unit is further provided in the first embodiment of the present disclosure; be.

Each process of steps S101 to S110 and S112 shown in FIG. 10 is the same as each process of steps S101 to S110 and S112 described with reference to FIG.

In step S110, the controller 17 estimates the charging resistor 32 calculated by the temperature estimator 16 at the time when the emergency stop signal is received (that is, when the controller 17 determines that the emergency stop signal is received in step S107). A determination is made as to whether the temperature exceeds a predetermined temperature threshold. If it is determined in step S110 that the estimated temperature of the charging resistor 32 exceeds the temperature threshold, the process proceeds to step S300, and if it is determined that the estimated temperature of the charging resistor 32 does not exceed the temperature threshold, the process proceeds to step S112. .

If it is determined in step S110 that the estimated temperature of the charging resistor 32 exceeds the temperature threshold, in step S300, the operator is alerted that the discharging circuit 15 will perform a non-discharging operation in the next step S111. to output an alarm. After that, the motor driving device 1 finishes its operation.

FIG. 11 is a flowchart showing the operation flow of the pre-charging circuit, the discharging circuit, the opening/closing unit, and the alarm output unit in the motor drive device according to the third embodiment, in which the alarm output unit is further provided in the second embodiment of the present disclosure; be.

Each process of steps S201 to S211 and S213 shown in FIG. 10 is the same as each process of steps S201 to S211 and S213 described with reference to FIG.

In step S211, the controller 17 estimates the charging resistance 32 calculated by the temperature estimator 16 at the time when the emergency stop signal is received (that is, when the controller 17 determines that the emergency stop signal has been received in step S209). A determination is made as to whether the temperature exceeds a predetermined temperature threshold. If it is determined in step S211 that the estimated temperature of the charging resistor 32 exceeds the temperature threshold, the process proceeds to step S300, and if it is determined that the estimated temperature of the charging resistor 32 does not exceed the temperature threshold, the process proceeds to step S213. .

If it is determined in step S211 that the estimated temperature of the charging resistor 32 exceeds the temperature threshold, in step S300, the operator is alerted that the discharging circuit 15 will perform a non-discharging operation in the subsequent step S212. to output an alarm. After that, the motor driving device 1 finishes its operation.

Next, a motor drive device according to a fourth embodiment of the present disclosure will be described with reference to FIGS. 9 and 12. FIG. In the fourth embodiment, in the first and second embodiments described above, an alarm is generated when the number of pre-charging operations performed by the pre-charging circuit during the predetermined time period exceeds a predetermined number of times threshold. is further provided with an alarm output unit for outputting

As shown in FIG. 9, the motor driving device 1 according to the fourth embodiment is configured such that when the number of pre-charging operations performed by the pre-charging circuit 14 during a predetermined time period exceeds a predetermined number of times threshold, It further includes an alarm output unit 22 that outputs an alarm. When the emergency stop signal and the emergency stop cancellation signal are alternately input to the control unit 17 during the temperature rise duration time U, the preliminary charging operation is executed a plurality of times during the temperature rise duration time U to charge the battery. Heat is accumulated in the resistor 32, the temperature rises, and the possibility of destruction due to fusing increases. Therefore, when the number of pre-charging operations performed by the pre-charging circuit 14 during the temperature rise duration U exceeds a predetermined number of times threshold, the alarm output unit 21 outputs an alarm to alert the operator. do.

For example, the maximum temperature rating of the charging resistor 32 is 150 [°C], the temperature rise duration U is 60 [seconds], and the temperature rise value T _rise of the charging resistor 32 is 10 [°C]. ], the charging resistor 32 reaches the maximum temperature rating of 150 (=13×10+20) [° C.] in 780 (=13×60) [seconds] when there are 13 precharging operations.

The number threshold K _th used for determining whether to output an alarm is expressed by the following equation 3, where T _max [° C.] is the maximum rated temperature of the charging resistor 32 .

Therefore, the alarm output unit 22 determines that the number of pre-charging operations performed by the pre-charging circuit 14 during the period of the temperature rise duration U during “U×K _th [seconds]” exceeds the predetermined number threshold. If exceeded, output an alarm. Note that the temperature rise duration U is obtained in advance through experiments as described above. For example, a notification unit (not shown) may be provided for using an alarm output from the alarm output unit 22 to notify that the charging resistor 32 may be damaged due to fusing. Examples of means of the notification unit include a display attached to the motor drive device 1 and its host control device, a display such as a personal computer, a portable terminal, and a touch panel. Further, for example, the notification unit may be realized by an acoustic device that emits sound such as voice, speaker, buzzer, chime, or the like. Alternatively, it may be printed out and displayed on a sheet of paper using a printer. Alternatively, it may be realized by appropriately combining these.

The alarm output unit 22 may be constructed, for example, in the form of a software program, or may be constructed by combining various electronic circuits and software programs. For example, when constructing these in a software program format, an arithmetic processing unit such as an MPU or DSP in the motor drive device 1 or in the machine provided with the motor drive device 1 is operated according to this software program to generate an alarm The function of the output unit 22 can be realized. Alternatively, it may be implemented as a semiconductor integrated circuit in which a software program that implements the functions of the alarm output unit 22 is written. Alternatively, a software program that implements the functions of the alarm output unit 22 may be stored in a storage medium. Circuit components other than the alarm output unit 22 are the same as the circuit components shown in FIG. 1 or FIG. Description is omitted.

FIG. 12 is a flow chart showing the operation flow of the pre-charging circuit and the alarm output section in the motor drive device according to the fourth embodiment in which the alarm output section is further provided in the first or second embodiment of the present disclosure.

The alarm output unit 22 in the motor drive device 1 according to the fourth embodiment is an alarm output unit 22 in the motor drive device 1 according to the first embodiment described with reference to FIG. 4 or the second embodiment described with reference to FIG. It is executed in parallel with the operations of the preliminary charging circuit 14 , the discharging circuit 15 , the control section 17 and the switching section 19 . FIG. 12 shows only the operations of the precharging circuit 14, the control section 17, the switching section 19 and the alarm output section 22. FIG.

In step S<b>401 , the alarm output unit 22 sets 0 (zero), which is an initial value, as the number i of preliminary charging operations performed by the preliminary charging circuit 14 .

In step S<b>402 , the control unit 17 determines whether or not an emergency stop cancellation signal has been received from the signal generation unit 18 . If it is determined in step S402 that the emergency stop cancellation signal has been received, the process proceeds to step S403.

In step S403, the controller 17 controls the charging resistance bypass switch 31 in the preliminary charging circuit 14 to open. As a result, the charging resistor 32 is included in the current path.

In step S404, the control unit 17 controls the opening/closing unit 19 to be closed. As a result, the switching unit 19 is kept closed and the charging resistor bypass switch 31 is kept open, so that the AC power from the AC power source 2 is input to the rectifier circuit 11 via the switching unit 19 and the charging resistor 32. and the pre-charging operation by the pre-charging circuit 14 is started. After that, a temperature rise duration U is entered in which a current flows through the charging resistor 32 and the temperature rises. The alarm output unit 22 measures the elapsed time from the start of step S404.

In step S405, the control unit 17 determines whether or not the preliminary charging operation by the preliminary charging circuit 14 has been completed. When the voltage of capacitor 12 (DC link voltage) reaches the predetermined charging voltage, control unit 17 determines that the preliminary charging operation by preliminary charging circuit 14 has been completed, and proceeds to step S406.

In step S406, the controller 17 controls the charging resistance bypass switch 31 in the precharging circuit 14 to close. As a result, a current path bypassing the charging resistor 32 is formed, and AC power from the AC power supply 2 is input to the rectifier circuit 11 via the open/close portion 19 and the charging resistor bypass switch 31 which are both closed. The rectifier circuit 11 converts the input AC power into DC power and outputs it to the DC link, and the inverter 13 converts the DC power in the DC link into AC power and supplies it to the motor 3 .

In step S407, the control unit 17 generates a power conversion command based on the rotational speed of the motor 3, the current flowing through the windings of the motor 3, a predetermined torque command, the operation program of the motor 3, and the like. The inverter 13 converts the DC power in the DC link into AC power according to the power conversion command received from the control unit 17 and supplies the AC power to the motor 3 . Motor 3 is driven based on AC power supplied from inverter 13 .

In step S<b>408 , the control unit 17 determines whether or not an emergency stop signal has been received from the signal generation unit 18 . If it is determined in step S408 that the emergency stop signal has been received, the process proceeds to step S409, and if it is determined that the emergency stop signal has not been received, the process returns to step S407.

In step S409, the control unit 17 controls the charging resistance bypass switch 31 in the preliminary charging circuit 14 to open. As a result, the charging resistor 32 is included in the current path.

In step S410, the alarm output unit 22 determines whether or not the temperature rise duration U is currently in progress. As described above, the alarm output unit 22 measures the elapsed time from the start of the preliminary charging operation in step S404, and based on whether the measured elapsed time is within the temperature rise duration time U, It is determined whether or not the temperature rise duration U is in progress. If it is determined in step S410 that the temperature rise duration U is in effect, the process proceeds to step S411, and if it is determined that the temperature rise duration U is not in effect, the process returns to step S402.

In step S<b>411 , the alarm output unit 22 increments the number i of preliminary charging operations by the preliminary charging circuit 14 by one.

In step S412, the alarm output unit 22 determines whether or not the number i of pre-charging operations performed by the pre-charging circuit 14 is equal to or greater than the number threshold _Kth . In step S412, if it is determined that the number i of preliminary charging operations is equal to or greater than the number threshold _Kth , the process proceeds to step S413; if it is determined that the number i of preliminary charging operations is less than the number threshold _Kth , step Return to S402.

In step S413, the alarm output unit 22 outputs an alarm. After that, the processing of the alarm output unit 22 ends.

REFERENCE SIGNS LIST 1 motor drive device 2 AC power supply 3 motor 11 rectifier circuit 12 capacitor 13 inverter 14 pre-charging circuit 15 discharge circuit 16 temperature estimator 17 controller 18 signal generator 19 switching unit 21, 22 alarm output unit 23 power supply unit for controller 31 charging resistor bypass switch 32 charging resistor 33 discharging resistor 34 discharging switch

Claims (10)

a rectifier circuit that converts AC power input from an AC power source into DC power and outputs the DC power;
a capacitor provided in a DC link on the DC output side of the rectifier circuit;
an inverter that converts the DC power in the DC link into AC power for driving a motor and outputs the AC power;
A pre-charging circuit having a charging resistor bypass switch and a charging resistor connected in parallel to the charging resistor bypass switch, wherein power flowing through the charging resistor bypass switch or the charging resistor and the rectifying circuit powers the capacitor. a preliminary charging circuit for preliminary charging;
a discharge circuit provided in the DC link, wherein the discharge circuit and the capacitor are electrically connected to discharge DC power accumulated in the capacitor; a discharge circuit selectively switched between a non-discharge operation in which electrical connection is cut;
a temperature estimator that sequentially calculates an estimated temperature of the charging resistor;
a control unit that controls the preliminary charging circuit and the discharging circuit;
with
The motor drive device, wherein the controller controls the discharge circuit to maintain the non-discharge operation when the estimated temperature exceeds a predetermined temperature threshold. The control unit controls the discharge circuit to maintain the non-discharge operation when the estimated temperature exceeds a predetermined temperature threshold when an emergency stop signal for emergency stop of the motor is received. The motor driving device according to claim 1. 3. The motor drive according to claim 2, wherein said controller controls said discharge circuit to perform said discharge operation when said estimated temperature does not exceed said temperature threshold when said emergency stop signal is received. Device. 4. The motor drive according to claim 2, wherein said control unit controls said discharge circuit to perform said non-discharge operation when receiving an emergency stop cancellation signal for canceling said emergency stop of said motor. Device. The controller opens the charging resistor bypass switch if the voltage of the DC link does not exceed a predetermined voltage threshold when an emergency stop cancellation signal for canceling the emergency stop of the motor is received. controlling the pre-charging circuit to keep the charging resistor bypass switch closed if the DC link voltage exceeds a predetermined voltage threshold when the emergency stop release signal is received; 5. The motor driving device according to any one of claims 2 to 4, which controls a circuit. After the controller controls the pre-charging circuit to open the charging resistor bypass switch when the voltage of the DC link does not exceed a predetermined voltage threshold when the emergency stop cancellation signal is received, 6. The motor driver of claim 5, further comprising controlling said precharge circuit to close said charging resistor bypass switch when said capacitor reaches a predetermined charging voltage. 7. The apparatus according to any one of claims 2 to 6, further comprising an alarm output unit that outputs an alarm when the estimated temperature exceeds the temperature threshold when an emergency stop cancellation signal for canceling the emergency stop of the motor is received. or the motor drive device according to claim 1. 7. The device according to any one of claims 2 to 6, further comprising an alarm output unit that outputs an alarm when the number of pre-charging operations performed by said pre-charging circuit during a predetermined time period exceeds a predetermined number of times threshold. 1. The motor drive device according to claim 1. The motor driving device according to any one of claims 2 to 8, further comprising a signal generation unit that generates the emergency stop signal and an emergency stop cancellation signal for canceling the emergency stop of the motor. further comprising an opening and closing unit for opening and closing an electric circuit between the AC power supply and the rectifier circuit;
When receiving an emergency stop signal for emergency stop of the motor, the control unit controls to open the opening and closing unit, and when receiving an emergency stop cancellation signal for canceling the emergency stop of the motor. The motor driving device according to any one of claims 1 to 9, wherein the opening/closing portion is controlled to be closed.

Images