JP2012196143A - Motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control device allowing achievement of reduction in size of the device and achievement of low cost.SOLUTION: A motor control device comprises: an inverter bridge circuit that includes an inverter bridge converting DC power from a DC power supply into AC power and supplying the AC power to a motor; a control circuit that outputs a PWM control signal to the inverter bridge circuit; a regenerative-power processing circuit that is connected in parallel to a smooth capacitor between the positive side and the negative side of the DC power supply; a brake-power processing circuit that is connected to an AC power supply line from the inverter bridge to the motor; a regenerative resistor that is included in the regenerative-power processing circuit and processes the regenerative power from the motor; and a common resistor that is included in the brake-power processing circuit and concurrently serves as a brake resistor processing the brake power from the motor.

Description

  The present invention reduces the size of a motor control device that includes a regenerative energy processing circuit that drives a motor and prevents overvoltage of a main circuit during regeneration from the motor, and a dynamic brake circuit (hereinafter referred to as a DB circuit) that forcibly stops the motor. About.

Regarding the necessity of the regenerative energy processing circuit and the DB circuit in the motor control device, the following is known.
FIG. 12 is a diagram showing a regenerative energy processing circuit and a DB circuit in the conventional motor control device, and FIG. 13 is a diagram showing simplification of the DB circuit in the conventional motor control device.
In general, a motor control device uses a three-phase AC power supply as an input to create a DC power supply by a rectifier circuit using a diode and a smoothing capacitor, and drives a three-phase motor by an inverter bridge that converts the DC power supply to a three-phase AC. Is.

Electric power is supplied from the inverter bridge circuit, and the motor drives the connected load. However, depending on the state of the load, the load may drive the motor, and the electric power may be regenerated to the motor control device side. At this time, the regenerative power is converted into direct current by the inverter bridge, stored in the smoothing capacitor, and the voltage of the smoothing capacitor increases. Since there is an upper limit to the DC voltage that can be withstood by the smoothing capacitor and the inverter bridge, it is necessary to protect the DC voltage from exceeding a certain level.
As a method for suppressing the increase of the DC voltage, a regenerative energy processing circuit including a resistor 3 and a semiconductor switch 5 connected in series to a DC wiring and including a protective diode 12 for the semiconductor switch 5 is used as shown in FIG. The diode 12 of the regenerative energy processing circuit is necessary for suppressing a surge voltage caused by the wiring inductance of the resistor 3 when the semiconductor switch 5 is turned off. When the DC voltage rises above the threshold value, the regenerative energy processing circuit turns on the semiconductor switch 5 by the control circuit and consumes the regenerative energy from the servo motor 4 by the resistor 3. Therefore, the resistor 3 of the regenerative energy processing circuit has to consume the regenerative electric energy from the servo motor 4 and requires a considerably large size resistor.

Also, when the servo motor is driving the load, if the device fails or a power failure occurs, the servo motor must be stopped immediately. As a technique for quickly stopping the servo motor, a DB circuit as shown in FIG. 12 is used. The servo amplifier stops the operation of the inverter bridge (consisting of the semiconductor switches 6 to 11 and the diodes 13 to 18) at the time of the rapid stop, and turns on the switch such as the relay 26 of the DB circuit, so that the servo amplifier 4 is turned on. The servo motor 4 stops when the remaining residual energy is consumed by the resistor 25 of the DB circuit. Like the resistor 3 of the regenerative energy processing circuit described above, the resistor 25 of the DB circuit requires a large size resistor depending on the capacity of the servo motor 4. Further, the DB circuit rectifies the alternating current output from the servo motor to direct current through the rectifier circuit (comprising diodes 19 to 24) and flows it to the resistor 25, so that the cost of the rectifier circuit can be reduced as shown in FIG. A circuit that uses diodes (diodes 14, 16, and 18) that include a part (diodes 22 to 24) of an inverter bridge (configured by semiconductor switches 6 to 11 and diodes 13 to 18) is also used.
As described above, since the conventional motor control device requires the regenerative energy processing circuit and the DB circuit as described above, it is necessary to provide an additional circuit and a large-sized resistor, respectively. There was a problem that it was not possible to reduce the price.

In order to solve this problem, the motor control device according to the first prior art is “related to a motor power supply device having an inrush current prevention circuit, an overvoltage protection circuit, and a dynamic braking circuit”. The purpose is to provide a motor power supply device that can reduce the number of components and reduce the product size and manufacturing cost by having the device (for example, see Patent Document 1).
FIG. 14 is a schematic configuration diagram of a motor control device according to the first prior art. In the figure, 1 is an AC power supply unit, 3 is a rectification unit, 5 is a capacitor, 7 is a motor, 9 is an inverter unit, 11 is an overvoltage protection switching element, 13 is a dynamic braking resistor, 15 is a resistor, and 17 is overvoltage protection. A diode 19 is a multi-contact relay. In addition, the code | symbol attached | subjected to drawing is demonstrated using the same thing as the code | symbol attached | subjected to patent document 1 which is the 1st prior art.

  The motor control device according to the first prior art states that “when the motor 7 is suddenly stopped when the motor 7 is driven or the power supply is turned off to stop the motor 7 driving, the control unit connects the multi-contact relay 19 to the third contact C. As a result, an excessive current generated when the motor 7 tries to rotate due to an external force flows through the resistor 15 through the diode provided in the inverter unit 9 and is consumed by the heat by the resistor 15. In other words, it is possible to prevent the motor 7 from rotating, that is, to perform a dynamic braking function. ”“ When the initial power is applied from the AC power supply unit 1, the control is performed. The unit connects the multi-contact relay 19 to the first contact A. At this time, the AC voltage (VL1-L2) supplied from the AC power supply unit 1 is rectified by the rectification unit 3. The voltage (VD1) rectified by the rectifying unit 3 is charged to the capacitor 5 through the resistor 15. That is, the resistor 15 performs an inrush current prevention function in a state where the multi-contact relay 19 is connected to the first contact A. That is.

Further, the motor control device in the second prior art is “related to a motor control device that controls a plurality of servo motors and the like capable of regenerative control”, and “regenerative processing and braking processing of a plurality of motors are simplified. It can be implemented with a configuration ”,“ It is possible to brake multiple motors at the same time in the event of a power failure without using a dedicated brake circuit ”, and“ Regeneration resistance of the regenerative processing circuit and regenerative current to this regenerative resistor ” Using multiple switching means, multiple motors can be braked in the event of a power failure, and moreover, multiple motors can be braked quickly, and the regenerative resistor is damaged or burned out during regenerative processing. The object is to provide a motor control device that is not allowed to occur (for example, Patent Document 2).
FIG. 15 is a schematic configuration diagram of a motor control device according to the second prior art. In the figure, 1A to 1C are motors, 2A to 2C are inverter circuits, 3 is a rectifier circuit, 4 is a main circuit capacitor, 5 is a voltage monitoring circuit, 6 is a regenerative resistor, and 7 and 7 'are regenerative transistors (switching means). 8, 8 'are control circuits (control signal generation circuits), 9A to 9C are inverter drive circuits, 10 is a control power supply circuit, 11 is a power supply monitoring circuit, and 12 is a regeneration detection circuit. In addition, the code | symbol attached | subjected to drawing is demonstrated using the same thing as the code | symbol attached | subjected to patent document 2 which is a 2nd prior art.

  The motor control device according to the second prior art is “a rush prevention resistor R having a large resistance value is connected in parallel to the power switch MS. Also, the input circuit of one polarity of the inverter circuits 2A to 2C and the main circuit Between the one terminal of the capacitor 4 (or one output terminal of the common power supply), a switch circuit that selectively enables power supply to the inverter circuits 2A to 2C is disposed, respectively. "The series circuit of the regenerative resistor 6 and the regenerative transistor (switching means) 7 forms part of a regenerative processing circuit that converts regenerative power into Joule heat." In the regenerative state and the brake state, the inverter circuit To appropriately control the switch circuits (TR1 to TR3) and the regenerative transistor (switching means) 7 that can selectively supply power to 2A to 2C. “Regenerative power from multiple inverter circuits can be regenerated by a single regenerative resistor and switching means, and the configuration of the control device is simplified, and the regenerative resistor of the regenerative processing circuit is used as a brake resistor. Thus, when the power source is in a power failure state, the brakes can be applied to a plurality of motors, so there is an advantage that it is not necessary to provide a dedicated brake circuit.

  In addition, the motor control device according to the third prior art relates to a motor control device such as a servo motor capable of regenerative control, and particularly a motor capable of quickly stopping the rotation of the motor when a power failure occurs. "Regarding the control device", "It is possible to brake the motor in the event of a power failure without using a dedicated brake circuit", and "Regenerative resistance of the regenerative processing circuit and regenerative current to flow through this regenerative resistance" Using the switching means, it is possible to brake the motor at the time of a power failure. ”Furthermore,“ a motor control device that can brake quickly and does not damage or burn out the regenerative resistor during regenerative processing. It is intended to “provide” (for example, Patent Document 3). FIG. 16 is a schematic configuration diagram of a motor control device according to the third prior art. In the figure, 1 is a motor, 2 is an inverter circuit, 3 is a rectifier circuit, 4 is a main circuit capacitor, 5 is a voltage monitoring circuit, 6 is a regenerative resistor, 7 is a regenerative transistor (switching means), and 8 is a control circuit (control) (Signal generation circuit), 9 is an inverter drive circuit, 10 is a control power supply circuit, 11 is a power supply monitoring circuit, and 12 is a regeneration detection circuit. In addition, the code | symbol attached | subjected to drawing is demonstrated using the same thing as the code | symbol attached | subjected to patent document 3 which is a 3rd prior art.

  The motor control device according to the third prior art states that “as a switching means used in the regeneration processing circuit, it is turned off when a control signal is inputted to the control terminal, and is turned on when no control signal is inputted to the control terminal. The regenerative power supplied from the motor 1 through the inverter circuit 2 is a regenerative resistor while the regenerative transistor 7 is turned on during a power failure at the power source. 6 is consumed as Joule heat and brakes are applied to the motor.

JP 2004-248488 A (page 4-6, FIG. 2) Japanese Unexamined Patent Publication No. 2000-188897 (page 6-10, FIG. 1) Japanese Patent Laid-Open No. 11-18464 (page 6-9, FIG. 1)

As described above, since a general motor control device requires a regenerative energy processing circuit and a DB circuit, each requires an additional circuit and a large-sized resistor, and the motor control device itself is downsized or reduced in price. There was a problem that could not.
In addition, in the motor control device (Patent Document 1) in the first prior art, a resistor for preventing an inrush current that may be relatively small can be omitted, but the regenerative energy processing circuit is not mentioned, and a large size is not mentioned. The resistance of the regenerative energy processing circuit and the DB circuit cannot be shared. In addition, by providing contacts on the DC power supply wiring, it is possible to reduce the number of parts by sharing resistance parts and reduce the product size and manufacturing cost, but during the operation of driving a normal servo motor, There is also a problem that the loss at the contact portion increases and the efficiency is lower than that of a general motor control device.
Further, in the motor control device (Patent Document 2) in the second prior art, since the semiconductor switch is provided on the wiring of the DC power source, the loss increases more greatly than the relay contact during normal operation. A cooling device for the switch is also required, and there is a problem that the efficiency is significantly reduced and the size is increased as compared with a general motor control device.
Further, in the motor control device (Patent Document 3) according to the third prior art, “As a switching means used in the regeneration processing circuit, when a control signal is input to the control terminal, it is turned off, and the control signal is input to the control terminal. Since the normally-on regenerative transistor 7 that is turned on when not being used is used ", dynamic braking cannot be performed when it is not during a power failure. Further, if the dynamic brake operation is performed when the power failure is not occurring, power is supplied from the DC power source to the resistor, so that the resistor burns out.
The present invention has been made in view of such problems, and includes a regenerative energy processing circuit and a DB circuit, which share the resistance of the regenerative energy processing circuit and the resistance of the DB circuit, and both circuits. It is an object of the present invention to provide a motor control device that can be simplified, suppress loss in both circuits when the servo motor is driven, and reduce the size or cost of the device itself.

In order to solve the above problem, the present invention is configured as follows.
A motor control device according to an aspect of the present invention includes a DC power supply, a smoothing capacitor connected between the positive and negative sides of the DC power supply, and converts DC power from the DC power supply into AC power and supplies the AC power to the motor. An inverter bridge circuit including an inverter bridge, a control circuit that outputs a PWM control signal to the inverter bridge circuit, a regenerative power processing circuit that is connected in parallel to the smoothing capacitor, and an AC power supply line from the inverter bridge to the motor A braking power processing circuit to be connected; a regenerative resistor included in the regenerative power processing circuit for processing regenerative power from the motor; and a braking resistor included in the braking power processing circuit for processing braking power from the motor; And a common resistance that also serves as a motor control device.

According to the motor control device of one aspect of the present invention, the resistance of the regenerative power processing circuit and the resistance of the braking power processing circuit can be shared, both circuits can be simplified, and loss in both circuits when the servo motor is driven can be reduced. Can be suppressed. In addition, a large-sized resistor requires a large space for storing, a space for cooling heat generation, and a cooling device such as a cooling FAN. However, by sharing the resistor, the necessary space and the cooling device are reduced. Therefore, it is possible to reduce the size or cost of the apparatus itself, and to save energy.
Further, since the resistance value of the regenerative operation and the braking operation can be adjusted by adding a simple circuit, the performance and safety of the servo drive device can be improved. Also, if you want to design the resistance for regeneration and the resistance for dynamic brake separately, or if you want to finely adjust the resistance value according to the situation, you can easily cope with it and operate both circuits optimally. Thus, the reliability of the motor control device itself can be improved.
Further, since the consumption amount of regenerative energy can be adjusted / increased by the PWM operation, the device itself can be further reduced in size or cost.

Schematic configuration diagram of a motor control device of the present invention The figure which shows the example of an electric current path at the time of the regeneration energy processing circuit operation | movement of this invention The figure which shows the example of a current pathway at the time of DB circuit operation | movement of this invention The figure which shows each switch operation example 1 at the time of the regeneration energy processing circuit operation | movement of this invention. The figure which shows each switch operation example 2 at the time of the regeneration energy processing circuit operation | movement of this invention. The figure which shows the operation example which increased the regeneration energy processing circuit operation | movement ratio of this invention. The figure which shows the operation example which adjusted the regeneration energy processing circuit operation | movement ratio of this invention. The figure which shows each switch operation example at the time of DB operation | movement of this invention The figure which shows the operation example which transfers to DB operation | movement from the regeneration energy processing circuit operation | movement of this invention The figure which shows the logic circuit example which produces | generates the operation signal of SW5 of this invention (A) The figure which shows the Example when increasing the resistance circuit of this invention (b) The figure which shows the other Example when increasing the resistance circuit of this invention The figure which shows the regenerative energy processing circuit and DB circuit in the conventional motor control apparatus. The figure which shows simplification of DB circuit in the conventional motor control apparatus Schematic configuration diagram of a motor control device according to the first prior art Schematic configuration diagram of a motor control device in the second prior art Schematic configuration diagram of a motor control device in the third prior art

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a motor control device of the present invention. In the figure, 1 is a DC power supply having no function of regenerating to an input power supply such as diode rectification, 2 is a smoothing capacitor, 3 is a resistor, 4 is a motor, 5 to 11 are semiconductor switches, 12 to 21 are diodes, and 30 is a control circuit. It is. In the figure, the same reference numerals as those shown in FIGS. 14 to 16 of the motor control devices in the first to third prior arts are attached, but they are not related to each other, and their functions and effects are completely different. Is different.
The regenerative energy processing circuit or DB circuit in the present invention is composed of the resistor 3, the semiconductor switch 5, the diode 12, and the diodes 19 to 21, and the resistor 3 is a resistor shared by both circuits.

  The regenerative energy processing circuit or the DB circuit connects the anodes of the diodes 19 to 21 to the output line connecting the motor 4 and the semiconductor switches 6 to 11, and connects all the cathodes of the diodes 19 to 21 to the resistor 3. The other end of the resistor 3 is connected to the collector of the semiconductor switch 5 and the anode of the diode 12, the emitter of the semiconductor switch 5 is connected to the negative terminal (N) of the DC power supply 1, and the cathode of the diode 12 is connected to the DC power supply 1. Connected to the positive terminal (P). The diode 12 is necessary for suppressing the surge voltage caused by the wiring inductance of the resistor 3 when the semiconductor switch 5 is turned off.

Each of the semiconductor switches 5 to 11 is controlled to be turned on / off by the control circuit 30. The control circuit 30 controls the inverter bridge composed of the semiconductor switches 6 to 11 and the diodes 13 to 18 to control the motor. 4 is driven. In the regenerative energy processing circuit or DB circuit, no current flows through the diodes 19 to 21, the resistor 3, the semiconductor switch 5, and the diode 12 during the normal operation of driving the motor 4 (the ON operation of the semiconductor switch 5 by the control circuit 30). Therefore, the efficiency of the motor control device does not decrease as compared with the conventional device, and the cooling device may be the same as the conventional device.
The control device 30 monitors the main circuit voltage (VPN) which is a voltage between the P and N terminals of the DC power source 1 and appropriately turns on and off the semiconductor switch 5.

FIG. 2 is a diagram showing an example of a current path during operation of the regenerative energy processing circuit of the present invention, and FIG. 3 is a diagram showing an example of a current path during operation of the DB circuit of the present invention. In the figure, the configuration denoted by the same reference numerals as those in FIG. 1 exhibits the same operational effects, and thus detailed description thereof is omitted.
In FIG. 2, the dotted arrow indicates the current path during regeneration. When the control circuit 30 in FIG. 1 turns on the semiconductor switches 5, 6, 8, and 10 as illustrated, the energy stored in the smoothing capacitor 2 is It is consumed by the resistor 3 through the current path.
In FIG. 3, the dotted arrow indicates the current path during DB. When the control circuit 30 in FIG. 1 turns on only the semiconductor switch 5 as shown in the figure, the DB energy from the motor 4 passes through the current path. Thus, it is consumed by the resistor 3.
Thus, by changing the semiconductor switch that is turned on during regeneration or DB, the resistor 3 can be shared, and the regenerative energy processing circuit and the DB circuit can be configured with a simple circuit configuration.

  FIG. 4 is a diagram showing an operation example 1 of each switch (semiconductor switches 5 to 11) when the regenerative energy processing circuit of the present invention is operated, and FIG. 5 is a diagram showing each switch (semiconductor switch 5) when the regenerative energy processing circuit of the present invention is operated. FIG. 11 is a diagram illustrating an operation example 2; In the figure, U, V, and W phase voltage commands and carrier waves are signals for the control circuit 30 in FIG. 1 to perform PWM control of the semiconductor switches 6 to 11, and SW5 to 11 are the semiconductor switches 5 to 11 in FIG. 1 is equivalent to a gate voltage signal when the semiconductor switches 5 to 11 are IGBTs or n-channel MOSFETs, a DB control signal, and a regenerative control signal under the condition that the control circuit 30 in FIG. The signal generated below and the main circuit voltage are the voltages between the P (positive) and N (negative) terminals of the DC power source 1 in FIG. 1, and the control circuit 30 monitors the main circuit voltage.

When the inverter bridge (corresponding to the semiconductor switches 6 to 11 and the diodes 13 to 18 in FIG. 1) performs the PWM operation as shown in FIG. 4, during the regenerative operation, that is, the regenerative energy from the motor 4 is on the motor controller side. Since the DC power supply 1 does not have a power regeneration function, the regenerative energy is stored in the smoothing capacitor 3 and the main circuit voltage rises.
However, in the PWM operation, the semiconductor switches 6, 8, 10 are on, the semiconductor switches 7, 9, 11 are off, and all the output voltages of the inverter bridge are the P (positive) terminal voltage of the DC power supply 1. The line voltage applied to the motor 4 becomes zero (line output zero voltage state), or the semiconductor switches 6, 8, and 10 are off, and the semiconductor switches 7, 9, and 11 are on. In a state where all output voltages of the inverter bridge are N (negative) terminal voltages of the DC power supply 1 and the line voltage applied to the motor 4 is zero (line output zero voltage state), the current is Since the wiring is closed in the wiring, the smoothing capacitor 3 is not charged.

  Here, when the main circuit voltage reaches ON Level, the control circuit 30 turns on the regeneration control signal, and the timing of the line output zero voltage state in which the regeneration control signal and the signals SW6, SW8, and SW10 are all turned on. Thus, the semiconductor switch 5 is turned on by turning on the SW5. In this way, the energy stored in the smoothing capacitor 2 is consumed by the resistor 3 through the current path as shown in FIG. 2, and as a result, the main circuit voltage decreases and reaches OFF Level. The control circuit 30 turns off the regeneration control signal, turns off SW5, and turns off the semiconductor switch 5. It should be noted that ON Level and OFF Level may be selected at a level that does not damage the parts to which the main circuit voltage is applied, such as the smoothing capacitor 2.

When the inverter bridge is not in the line output zero voltage state, the regenerative energy moves from the motor to the motor controller side and the voltage of the smoothing capacitor rises as shown in FIG. To do. On the other hand, in the line output zero voltage state, the regenerative energy of the motor is closed in the motor and is not output to the outside.
As described above, when the semiconductor switch 5 is turned on while the semiconductor switches 6, 8, and 10 are on and the line output is at zero voltage, the energy stored in the smoothing capacitor of the main circuit is transferred to the resistor and consumed. At this time, the sum of the current of the motor and the current flowing from the smoothing capacitor to the resistor flows to the semiconductor switches 6, 8, and 10 depending on the load current direction of the motor, and the loss of the semiconductor switch is increased as compared with the conventional motor control device. Sometimes. However, since the regenerative energy process originally changes energy into a loss of resistance, the increase in loss during this operation has no effect on the efficiency of the motor control device. In addition, it is necessary to determine the value of the resistor 3 so that the increase in loss due to the increase in current does not exceed the cooling capacity of the semiconductor switches 5, 6, 8, and 10, or to limit the amount of regenerative energy on the driving load side. .

  The example shown in FIG. 4 is an example in which, during the PWM period (between the peaks of the carrier wave), the main circuit voltage once exceeds ON Level and is reduced to OFF Level by regenerative energy processing. From the balance with the energy that can be consumed by the resistor 3, the regenerative energy processing may continue over a plurality of PWM periods as shown in FIG.

FIG. 6 is a diagram showing an operation example in which the regenerative energy processing circuit operation ratio of the present invention is increased, and FIG. 7 is a diagram showing an operation example in which the regenerative energy processing circuit operation ratio of the present invention is adjusted. In the figure, the description of the same signal name as in FIGS. 4 and 5 has the same function, and thus detailed description thereof is omitted.
As described above, the regenerative energy processing operation by the resistor 3 is performed only under the condition of the line output zero voltage state in which the semiconductor switches 6, 8, and 10 are all turned on. The period of the line output zero voltage state depends on the output voltage of the inverter bridge, and when the output voltage is high, this period becomes very short. Under the condition of regenerating power from the motor 4, the inverter output voltage <the motor voltage (the motor voltage depends on the motor rotation speed), so that the period of the line output zero voltage tends to be secured to some extent.

  When it is necessary to quickly reduce the main circuit voltage once exceeding the ON level, the period of the line output zero voltage state in which the semiconductor switches 6, 8, and 10 are all turned on may be lengthened as shown in FIG. . That is, by adding the same amount of offset to the three-phase voltage command (U, V, W-phase voltage command), the period of the line output zero voltage state in which the semiconductor switches 6, 8, 10 are all turned on is lengthened. can do. Adding the same amount of offset to the three-phase voltage command (U, V, W-phase voltage command) shortens the period of the line output zero voltage state in which the semiconductor switches 7, 9, and 11 are all turned on. Then, adjustment is made to lengthen the period of the line output zero voltage state in which all the semiconductor switches 6, 8, and 10 are turned on, and the main circuit voltage that once exceeds the ON level is quickly reduced. In this case, the inter-terminal voltage (line voltage) of the motor 4 does not change, so that much regenerative energy can be consumed without affecting the driving / regeneration of the motor 4. Further, this period adjustment (adjustment for adding the same amount of offset to the three-phase voltage command (U, V, W-phase voltage command)) is performed only when necessary as shown in FIG. It may be returned to the period.

FIG. 8 is a diagram showing an example of each switch operation during the DB operation of the present invention. In the figure, the description of the same signal name as in FIGS. 4 to 7 has the same function, and thus the detailed description is omitted.
The dynamic brake operation of the motor control device according to the present invention is performed after the control circuit 30 in FIG. 1 monitors the power failure of the input power supply, the device failure, etc., and determines the necessity of emergency stop using the dynamic brake. is there.
When performing dynamic braking, the control circuit turns on the DB control signal, turns off all of the signals SW6 to SW11 of the semiconductor switches 6 to 11, turns on the signal SW5 of the semiconductor switch 5, and turns on the semiconductor switch 5. Let At this time, the current path during DB passes through a path as shown in the example of FIG.

FIG. 9 is a diagram showing an operation example of transition from the regenerative energy processing circuit operation of the present invention to the DB operation. In the figure, the description of the same signal name as in FIGS. 4 to 8 has the same function, and thus detailed description is omitted.
As described above, when dynamic braking is performed, energy from the motor is consumed by the resistor 3 via the current path during DB shown in FIG. 3, so that the main circuit voltage cannot be lowered. However, the smoothing capacitor 2 is no longer charged from the motor, so the rise in the potential of the smoothing capacitor also stops. If the main circuit voltage is less than ON Level, there is no voltage breakdown of the components such as the smoothing capacitor 2 and so on. There is no problem even if it is done.
Therefore, even when transitioning from the regenerative energy processing circuit operation to the DB operation, if the main circuit voltage is equal to or less than ON Level, there is no problem even if dynamic braking is performed. Conversely, while the main circuit voltage during operation of the regenerative energy processing circuit is equal to or higher than ON Level, sequence processing such as dynamic braking is not performed, or if priority is given to protection of the load device, dynamic braking is performed, and ON Level A value slightly exceeding the value must be designed to a level that does not destroy the parts to which the main circuit voltage is applied, such as the smoothing capacitor 2.

  FIG. 10 is a diagram showing an example of a logic circuit that generates the operation signal of SW5 of the present invention. The operation signal of SW5 from SW6, 8, and 10 and the regeneration control signal and the DB control signal in FIGS. This is an example of a logic circuit that generates A configuration with such a simple logic circuit is possible, and the motor control device can be realized at low cost.

FIG. 11A is a diagram showing an embodiment when the resistance circuit of the present invention is increased, and FIG. 11B is a diagram showing another embodiment when the resistance circuit of the present invention is increased. In the figure, reference numeral 27 denotes a semiconductor switch, 28 denotes a resistor, and 29 denotes a diode. The configurations denoted by the same reference numerals as those in FIGS. 1 to 3 have the same operational effects, and thus detailed description thereof is omitted. .
Since the power consumption of regenerative energy and the power consumption of dynamic brake are determined by the capacity of the load device used by the motor control device and its operating conditions, it is known that there are different optimum values depending on the conditions. ing.
The regenerative energy depends on the load and is about several to several tens of percent of the motor control device, and the resistance value R1 is designed when the motor control device is used. In addition, the dynamic brake has a motor-specific value because the optimum resistance value R2 for stopping in the shortest time is determined by the winding inductance, winding resistance, and rotation speed of the motor.

In general, the optimum resistance value R2 for the dynamic brake is a low value, and R1> R2. When the resistance of the regenerative energy processing circuit and the DB circuit is shared as in the motor control device of the present invention, the resistance at the time of regeneration is a pulse operation, so the resistance utilization rate per unit time is D (<1.0). When the resistance value is R2, the equivalent regenerative resistance value is R1 = R2 / D, which satisfies the condition of R1> R2.
Therefore, the capacity of the resistor is generally larger for the regenerative resistor, and the resistor size may be designed to match the required amount of regenerative energy consumption.

Further, when it is desired to design the regenerative resistor and the dynamic brake resistor separately, or when it is desired to finely adjust the resistance value according to the situation, the semiconductor switch 27 is used as shown in FIGS. Further, the resistance 28 and the diode 29 are increased, and the resistance 3 and the resistance 4 are connected in series or in parallel, so that the resistance value of each operation can be changed to be close to the optimum value.
Although FIG. 11 shows an example in which one resistor circuit is added, the number of extensions may be further increased. In addition, if a large number of resistors are connected in parallel, the resistance value can be finely adjusted and the force at the time of braking can be varied depending on whether the resistors are valid or invalid.

DESCRIPTION OF SYMBOLS 1 DC power supply 2 Smoothing capacitor 3, 25, 28 Resistance 4 Motor 5-11, 27 Semiconductor switch 12-21, 29 Diode 30 Control circuit

Claims (8)

DC power supply,
A smoothing capacitor connected between the positive and negative sides of the DC power supply;
An inverter bridge circuit including an inverter bridge that converts DC power from the DC power source into AC power and supplies the motor to the motor;
A control circuit for outputting a PWM control signal to the inverter bridge circuit;
A regenerative power processing circuit connected in parallel to the smoothing capacitor;
A braking power processing circuit connected to an AC power supply line from the inverter bridge to the motor;
A common resistor that serves as both a regenerative resistor that is included in the regenerative power processing circuit and processes regenerative power from the motor, and a braking resistor that is included in the braking power processing circuit and processes braking power from the motor;
A motor control device comprising:   A semiconductor switch included in the regenerative power processing circuit for controlling processing of the regenerative power at the regenerative resistor; a semiconductor switch included in the braking power processing circuit for controlling processing of the braking power at the braking resistance; The motor control device according to claim 1, further comprising a common semiconductor switch that also serves as a power source. When the control circuit is a dynamic brake, all the inverter bridges are turned off, and the semiconductor switch is turned on.
3. The motor according to claim 2, wherein in the case of regeneration, the semiconductor switch is turned on at the timing of the PWM control signal in which all output voltages of the inverter bridge are positive voltages of the DC power supply. Control device. When the control circuit is a dynamic brake, all the inverter bridges are turned off, and the semiconductor switch is turned on.
3. The motor control according to claim 2, wherein in the case of regeneration, the semiconductor switch is turned on at a timing of the PWM control signal at which a line voltage applied to the motor from the inverter bridge becomes zero. apparatus.   5. The control circuit according to claim 1, wherein the control circuit adjusts the time of the PWM control signal in which all output voltages of the inverter bridge are positive voltages of the DC power supply. 6. Motor control device.   The motor control device according to claim 5, wherein the control circuit adjusts the time of the PWM control signal by adding an offset amount to a voltage command for generating the PWM control signal.   5. The control circuit according to claim 1, wherein the PWM control signal time during which the output voltage of the inverter bridge is all the positive voltage of the DC power supply is varied during the PWM period. The motor control apparatus of Claim 1.   8. The control circuit according to claim 7, wherein the control circuit adds an offset amount to the voltage command for generating the PWM control signal to vary the time of the PWM control signal during the PWM cycle. Motor control device.

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