JP5804984B2 - Motor drive device - Google Patents

Description

  The present invention relates to a motor driving device that drives a motor.

  Currently, motors are mounted on all products such as industrial equipment, in-vehicle equipment, home appliances and information equipment. A motor, more specifically, a rotor included in the motor, is rotated by application of voltage by a motor driving device, and rotates a rotating object connected to the rotor.

  Further, the motor has a power generating action. Therefore, when the motor drive device and the motor are electrically connected, the rotating object is rotated by an external force, and when the motor rotates in conjunction with the rotation of the rotating object, an induced voltage is generated and generated. The induced voltage is applied to the components constituting the motor drive device.

  When the motor is rotated by applying a voltage to the motor while the motor is rotating in conjunction with the rotation of the rotating object due to the external force, a very large induced voltage is generated. There is a risk of damage to parts in the drive.

  In order to prevent such breakage of parts, it is necessary to suppress the rotation speed of the motor by braking the rotation of the motor before the motor driving device drives the motor.

  Patent Document 1 discloses a motor driving device that brakes rotation of a motor before the motor driving device drives the motor. This motor driving device discharges an induced voltage generated by the rotation of the motor when the rotation speed of the motor rotating by an external force is equal to or higher than a predetermined speed before driving the motor. It consumes energy to use and brakes the rotation of the motor.

Patent Documents 2 and 3 each disclose a motor driving device that brakes the rotation of the motor.
The motor driving device described in Patent Document 2 shorts between terminals of the motor when the rotational speed of the motor is equal to or higher than the first predetermined speed. Thereby, the induced voltage generated by the rotation of the motor is applied to the winding resistance mounted on the stator of the motor, the rotational energy of the motor is consumed, and the rotation of the motor is braked.

  Furthermore, the motor drive device described in Patent Document 2 is arranged between the motor terminals so as to rotate the motor in the direction opposite to the motor rotation direction when the rotation speed of the motor is less than the first predetermined speed. A voltage is applied to brake the rotation of the motor. The motor driving device described in Patent Document 2 naturally reduces the rotation of the motor when the rotation speed of the motor is equal to or lower than a second predetermined speed that is slower than the first predetermined speed.

  The motor drive device described in Patent Document 3 generates a magnetic attractive force in a plurality of coils by passing a direct current through the plurality of coils of the motor, and brakes the rotation of the motor by the generated magnetic attractive force. To do.

JP 2011-030330 A JP 2007-160218 A Japanese Patent Laid-Open No. 10-341590

  However, since the motor drive device described in Patent Document 1 cannot adjust the torque generated when braking the rotation of the motor, it cannot brake the rotation of the motor with an appropriate torque. For this reason, there exists a possibility that rotation of a motor may be braked rapidly. For example, when a gear is connected to the rotor of the motor, the gear tooth contact is increased by the rapid braking of the rotation of the motor, the gear is damaged, and the life of the gear is shortened.

  In the motor driving device described in Patent Document 2, when the rotation speed of the motor is equal to or higher than the first predetermined speed, the rotation of the motor is braked by a short circuit between the motor terminals. There is a problem that the generated torque cannot be adjusted and the rotation of the motor cannot be braked with an appropriate torque. Furthermore, in the motor drive device described in Patent Document 2, braking is performed by short-circuiting between motor terminals when the rotational speed of the motor is high, and the torque generated by the braking is small. There is also a problem that it cannot be decelerated quickly.

  Further, in the motor driving device described in Patent Document 2, when the rotation speed of the motor is equal to or lower than the second predetermined speed, the rotation of the motor is naturally decelerated. When external force is applied, the rotation of the motor is accelerated again. For this reason, the motor drive device described in Patent Document 2 has a problem that the state in which the rotation of the motor is decelerated or stopped cannot be maintained.

  In addition, when braking the rotation of the motor by the method described in Patent Document 3, the motor drive device must continue to pass a direct current through a plurality of coils included in the motor, and there is a problem that power is wasted. is there.

  The present invention has been made in view of such circumstances, and an object of the present invention is to quickly decelerate the motor rotation by an external force by braking with an appropriate torque, and the rotation of the motor is decelerated or stopped. An object of the present invention is to provide a low power consumption motor driving device capable of maintaining a state.

A motor driving device according to the present invention detects a rotation speed of the motor and a receiving means for receiving a rotation instruction of the motor in a motor driving device that drives the motor by applying a voltage between terminals of the motor. And when the rotation speed detected by the detection unit is less than a first speed, the terminals are short-circuited, and the detection unit when the detected rotation speed is the first speed or more, constructed tear Ri to apply a voltage between the terminals so that the torque is generated in the direction to prevent the rotation of said motor, said first speed The torque generated in the motor due to the short circuit between the terminals is the maximum rotational speed, and the torque generated in the direction that prevents the rotation when the rotational speed is the first speed is The rotational speed is characterized that you have substantially coincides with the torque generated by the short circuit between said terminals when the first is speed.

In the present invention, when the receiving means does not receive a motor rotation instruction and the rotation speed of the motor detected by the detection unit is equal to or higher than the first speed, the motor is prevented from rotating . A voltage is applied between the motor terminals to brake the rotation of the motor so that torque is generated in a direction that increases as the rotational speed of the motor increases . And when the receiving means has not received a motor rotation instruction, and when the rotation speed of the motor detected by the detector is less than the first speed, the motor terminals are short-circuited to rotate the motor. Braking.
When applying a voltage between the motor terminals so that torque is generated in a direction that prevents the motor from rotating, adjusting the voltage applied between the motor terminals to adjust the torque in the direction that prevents the motor from rotating Is possible. Furthermore, when the rotational speed of the motor becomes less than the first speed and becomes sufficiently small, the rotation of the motor is braked by a short circuit between the terminals of the motor.
For this reason, it becomes possible to brake the rotation of the motor with an appropriate torque, and the rotation of the motor is quickly decelerated. Further, while the motor terminals are short-circuited, it is not necessary to apply a voltage to the motor, and the power consumed by braking the rotation of the motor is low. Furthermore, since the rotation of the motor is always braked while the receiving unit does not receive the rotation instruction, the rotation of the motor once decelerated is not accelerated again by an external force. For this reason, the state where the rotation of the motor is decelerated or stopped is maintained.

In the present invention, the first speed at which the braking caused by the torque generated in the direction that hinders the rotation of the motor is switched to the braking caused by the short circuit between the terminals of the motor is the rotational speed at which the torque generated in the motor due to the short circuit is maximized. is there. For this reason, the braking by the short circuit between the terminals of the motor becomes more effective.

In the present invention, when the rotation speed of the motor is the first speed, the torque generated in the direction that prevents the rotation of the motor and the torque generated by a short circuit between the terminals of the motor are substantially the same. For this reason, it is possible to smoothly switch from braking by torque generated in a direction that hinders rotation of the motor to braking by short circuit between the terminals of the motor. Therefore, when the braking is switched, the torque does not fluctuate rapidly and does not give a large impact to the rotating object of the motor, and there is no possibility that the rotating object is damaged.

  In the motor driving device according to the present invention, when the receiving unit receives a rotation instruction, and the rotation speed detected by the detection unit is equal to or higher than a second speed, torque is generated in a direction that prevents the rotation. Thus, a voltage is applied between the terminals, and the rotation of the motor is started when the rotation speed detected by the detection unit is less than a second speed.

  In the present invention, even when the receiving means receives the rotation instruction, if the rotation speed detected by the detection unit is equal to or higher than the second speed, the rotation of the motor is started without starting the rotation of the motor. The motor is braked by applying a voltage between the terminals so as to generate torque in the direction to prevent it. When the receiving unit receives a rotation instruction and the detection unit detects a rotation speed less than the second speed, rotation of the motor is started.

  Accordingly, since the motor starts rotating when the rotational speed is less than the second speed and is sufficiently slow, the induced voltage generated when the motor starts rotating is surely reduced. For this reason, damage to the components connected to the motor is reliably prevented.

  According to the present invention, a motor drive device with low power consumption can be realized in which the rotation of the motor by an external force can be braked with an appropriate torque and quickly decelerated, and the rotation of the motor can be decelerated or stopped. can do.

It is a circuit diagram which shows the principal part structure of the motor drive device which concerns on this invention. It is a graph which shows the characteristic of the torque which arises by short circuit braking and delayed phase braking. It is a flowchart which shows the procedure of the operation | movement which a control part performs. It is a flowchart which shows the procedure of the operation | movement which a control part performs.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.
FIG. 1 is a circuit diagram showing a main configuration of a motor drive device according to the present invention. The motor drive device 1 is connected to an AC power source 2 that outputs an AC voltage, a motor 3, and one terminal of a switch 4 that outputs a rotation instruction for the motor 3. The other terminal of the switch 4 is connected to a circuit (not shown).

  The motor 3 is a three-phase brushless DC motor, and coils Lu, Lv, and Lw are wound individually on a stator (not shown) of the motor 3. One terminal of the coil Lu is connected to one terminal of each of the coils Lv and Lw, and the other terminal of each of the coils Lu, Lv and Lw is connected to the motor driving device 1 separately.

  When a pulse voltage corresponding to an AC voltage is applied between the terminals of the motor 3, that is, between the other terminals of the coils Lu, Lv, and Lw by the motor driving device 1, the motor 3, more specifically, the motor 3 is A rotor (not shown) having the rotation rotates. Due to the rotation of the motor 3, a rotating object connected to the rotor of the motor 3, for example, a gear rotates.

  The motor 3 detects the magnitude of a magnetic field generated from a rotor composed of permanent magnets in addition to the stator, rotor and coils Lu, Lv, Lw, and the output voltage changes greatly when the magnetic poles of the rotor are switched. It has hall sensors Hu, Hv, Hw.

  The switch 4 is a switch for the motor driving device 1 to receive a rotation instruction and a stop instruction for the motor 3 and is turned on / off by a user. For example, when the circuit connected to the switch 4 has a resistor, one terminal of the resistor is connected to the other terminal of the switch 4 and a certain voltage is applied to the other terminal of the resistor When the person turns on the switch 4, a voltage equal to or higher than a predetermined voltage is applied to the motor driving device 1, and the motor driving device 1 receives a rotation instruction. In addition, when the user turns off the switch 4 in the above state, the voltage applied to the motor drive device 1 via the switch 4 becomes a predetermined voltage or less, and the motor drive device 1 accepts a stop instruction.

  The motor drive device 1 includes a rectifier circuit 11, a capacitor 12, an inverter circuit 13, a speed detection unit 14, a storage unit 15, and a control unit 16. The rectifier circuit 11 is connected to both ends of the AC power supply 2 and the capacitor 12, and both ends of the capacitor 12 are further connected to the inverter circuit 13.

  The AC voltage output from the AC power supply 2 is rectified to a DC voltage by the rectifier circuit 11, and the rectified DC voltage is smoothed by the capacitor 12 and applied to the inverter circuit 13.

  The inverter circuit 13 includes FETs (Field Effect Transistors) 30, 31,. The drains of the FETs 30, 32, and 34 are connected to one terminal of the capacitor 12, and the sources of the FETs 31, 33, and 35 are connected to the other terminal of the capacitor 12.

  The source of the FET 30 is the drain of the FET 31 and the other terminal of the coil Lu of the motor 3. The source of the FET 32 is the drain of the FET 33 and the other terminal of the coil Lv of the motor 3. The source of the FET 34 is the FET 35. And the other terminal of the coil Lw of the motor 3.

  The gates of the FETs 30, 31,..., 35 are connected to the control unit 16 separately. Each of the FETs 30, 31,..., 35 is an N channel type FET and functions as a semiconductor switch. For each of the FETs 30, 31,..., 35, when a voltage higher than a predetermined voltage is applied to the gate by the control unit 16, a current can flow from the drain to the source. When the voltage applied to is adjusted to be lower than a predetermined voltage, the current is turned off without flowing from the drain to the source.

  The inverter circuit 13 converts the DC voltage that has been rectified and smoothed by the rectifier circuit 11 and the capacitor 12 by the control unit 16 to turn on / off the FETs 30, 31,. Is converted into a pulse voltage corresponding to. The inverter circuit 13 rotates the motor 3 by applying the converted pulse voltage between the terminals of the motor 3. The inverter circuit 13 applies a substantial AC voltage between the terminals of the motor 3 by adjusting the pulse width of the pulse voltage according to the absolute value of the AC voltage to be applied between the terminals of the motor 3.

  The speed detector 14 is connected to each of the hall sensors Hu, Hv, Hw of the motor 3 and detects the rotational speed of the motor 3, more specifically the rotor speed, from the output voltages of the hall sensors Hu, Hv, Hw. To do. The speed detector 14 detects a large change in the output voltage of each of the Hall sensors Hu, Hv, and Hw that occurs when the magnetic poles of the rotor are switched, and determines the rotation speed of the motor 3 from the time interval at which the large change in the output voltage is detected. Detected.

Further, the speed detection unit 14 calculates the rotational position of the rotor, that is, the phase of the induced voltage generated by the rotation of the motor 3, from the output voltages of the Hall sensors Hu, Hv, and Hw and the detected rotational speed of the motor 3. To do. Specifically, the speed detection unit 14 detects the switching position between the S pole and the N pole of the rotor from a large change in the output voltage of each of the Hall sensors Hu, Hv, and Hw. The speed detector 14 calculates the angle at which the rotor has rotated from the switching position based on the product of the elapsed time from the time when the switching position is detected and the detected rotational speed. The speed detector 14 calculates the rotational position of the rotor, that is, the phase of the induced voltage, from the detected switching position and the calculated rotational angle of the rotor. The speed detection unit 14 notifies the control unit 16 of the detected rotation speed of the motor 3 and the calculated induced voltage phase.
The speed detector 14 corresponds to a detector in the claims.

  The storage unit 15 stores a target rotational speed of the motor 3 that is rotated when the motor driving device 1 receives an instruction to rotate the motor 3.

  The control unit 16 is connected to one terminal of the switch 4 and receives a start instruction and a stop instruction from the user. During the preparation period from when the power switch (not shown) of the motor drive device 1 is turned on to the start of the motor drive device 1 until the start instruction is received, the control unit 16 detects the rotation speed of the motor 3 detected by the speed detection unit 14. Is read, the rotational speed of the motor 3 rotating in conjunction with the rotation of the rotating object due to the external force is recognized.

  When the control unit 16 reads the rotation speed of the motor 3 that is equal to or higher than the rotation speed N1 during the preparation period, the voltage between the terminals of the motor 3 is delayed with respect to the phase of the induced voltage calculated by the speed detection unit 14. Is applied to generate torque in a direction that hinders the rotation of the motor 3 to brake the rotation of the motor 3. This braking of the rotation of the motor 3 is hereinafter referred to as delayed phase braking. The control unit 16 adjusts the voltage applied between the terminals of the motor 3 by turning on / off the FETs 30, 31,..., 35 of the inverter circuit 13 separately, and performs delayed phase braking.

  When the controller 16 reads the rotational speed of the motor 3 less than the rotational speed N1 during the preparation period, the terminals of the motor 3 are short-circuited by turning on the FETs 31, 33, and 35, respectively. As a result, the induced voltage generated by the rotation of the motor 3 is applied to the winding resistances of the coils Lu, Lv, and Lw, the rotational energy of the motor 3 is consumed, and the rotation of the motor 3 is braked. Hereinafter, braking due to a short circuit between the terminals of the motor 3 is referred to as short circuit braking.

  FIG. 2 is a graph showing characteristics of torque generated by short circuit braking and delayed phase braking. FIG. 2A shows torque characteristics by short-circuit braking, and FIG. 2B shows torque characteristics by delayed phase braking. FIG. 2C shows the torque characteristics of the short-circuit braking and the delayed phase braking. 2A, 2B, and 2C each show the torque with respect to the rotation speed of the motor 3, and the torque generated in the direction that prevents the rotation of the motor 3 is shown as a negative torque. V1, V2, and V3 are amplitude values of the AC voltage that is applied between the terminals of the motor 3 by the inverter 13 in order to perform delayed phase braking, and the amplitude values increase in the order of V1, V2, and V3.

  As shown in FIG. 2A, the torque generated by the short-circuit braking increases with the increase in the rotation speed until the rotation speed of the motor 3 changes from zero to a predetermined speed. When the rotation speed exceeds the predetermined speed, the rotation speed increases. Decreases with. The rotational speed N1 that is switched from the delayed phase braking to the short-circuit braking is set to the predetermined speed at which the torque generated by the short-circuit braking becomes the maximum value T1. The rotation speed N1 corresponds to the first speed in the claims.

  As shown in FIG. 2B, the torque generated by the delayed phase braking increases as the rotational speed of the motor 3 increases when the amplitude value of the AC voltage applied between the terminals of the motor 3 is the same. Further, the torque generated by the delayed phase braking increases as the amplitude value of the AC voltage applied between the terminals of the motor 3 becomes V1, V2, and V3 at the same rotational speed.

  The controller 16 brakes the rotation of the motor 3 due to an external force by using both short-circuit braking and delayed phase braking during the preparation period. This braking method will be described with reference to FIG. 2C. When the rotational speed detected by the speed detection unit 14 is N1 or more during the preparation period, the control unit 16 converts a pulse voltage corresponding to an AC voltage that generates torque in a direction that prevents the motor 3 from rotating. 13 is applied between the terminals of the motor 3. As a result, the control unit 16 performs delayed phase braking to decelerate the rotation of the motor 3. Here, the control unit 16 adjusts the amplitude value of the AC voltage applied between the terminals of the motor 3 according to the rotational speed detected by the speed detection unit 14 when performing delayed phase braking. Adjust the torque generated in the direction that prevents rotation.

  The controller 16 switches from delayed phase braking to short-circuit braking when the rotation speed of the motor 3 is decelerated and the rotational speed detected by the speed detector 14 becomes N1. At this time, during the delayed phase braking, when the rotational speed detected by the speed detection unit 14 is N1, the control unit 16 transmits an AC voltage having an amplitude value of V2 between the inverter 13 and the motor 3 terminal. It is comprised so that it may apply to. Here, as shown in FIG. 2C, the amplitude value V2 is an amplitude value at which the torque is approximately T1 when the rotational speed is N1.

  Since the rotational speed of the motor 3 that switches from the delayed phase braking to the short-circuit braking is the rotational speed N1 at which the torque generated in the motor 3 by the short-circuit braking is maximized, the short-circuit braking is performed more effectively.

  Furthermore, at the rotational speed N1 of the motor 3 that switches from delayed phase braking to short circuit braking, the torque generated by each of the delayed phase braking and short circuit braking is substantially the same, so switching from delayed phase braking to short circuit braking is smooth. is there. For this reason, when the delayed phase braking is switched to the short-circuit braking, the torque generated in the motor 3 does not fluctuate rapidly and a large impact is not applied to the rotating object of the motor 3, and the rotating object is prevented from being damaged. .

  When the rotational speed detected by the speed detector 14 is less than N1 during the preparation period, the controller 16 decelerates the rotation of the motor 3 by short-circuit braking, and even if the rotational speed of the motor 3 becomes zero, The short-circuit braking is continued until the rotation instruction 3 is received.

  For this reason, since the rotation of the motor 3 is always braked during the preparation period, the rotation of the motor 3 once decelerated or stopped is not accelerated again by an external force, and the state where the rotation of the motor 3 is decelerated or stopped is maintained. Is done. Furthermore, it is not necessary to apply a voltage between the terminals of the motor 3 while the control unit 16 performs short-circuit braking, and the power consumed by braking the rotation of the motor 3 is low.

When receiving the rotation instruction of the motor 3 from the switch 4, the control unit 16 reads the rotation speed of the motor 3 detected by the speed detection unit 14, and rotates in conjunction with the rotation of the rotating object due to the external force. The rotational speed of the motor 3 is recognized. The control unit 16 determines whether or not the read rotation speed of the motor 3 is less than the rotation speed N2 at which no excessive induced voltage is generated when the motor 3 starts rotating by applying a voltage between the terminals of the motor 3. Determine.
The rotational speed N2 corresponds to the second speed in the claims.

  When it is determined that the rotation speed of the read motor 3 is equal to or higher than N2, as a result of the determination, the control unit 16 has a phase delayed from the phase of the induced voltage calculated by the speed detection unit 14 between the terminals of the motor 3. Delayed phase braking is performed by applying a voltage. After performing the delayed phase braking, the control unit 16 reads the rotation speed detected by the speed detection unit 14 again and determines whether or not the read rotation speed is less than N2. The controller 16 continues to perform delayed phase braking until the rotational speed detected by the speed detector 14 becomes less than N2.

  When the controller 16 determines that the rotational speed read from the speed detector 14 is less than the rotational speed N2, the controller 16 responds to the AC voltage by turning on / off the FETs 30, 31,. A pulse voltage is applied between the terminals of the motor 3 to start the rotation of the motor 3.

  Therefore, since the motor 3 starts to rotate when the rotational speed is less than N2 and is sufficiently slow, the induced voltage generated when the motor 3 starts to rotate can be reliably lowered and connected to the motor 3. It is possible to reliably prevent damage to the parts.

After the rotation of the motor 3 starts, the control unit 16 rotates the motor 3 at the target rotation speed stored in the storage unit 15. When the control unit 16 receives an instruction to stop the motor 3 from the switch 4, the FET 30 is configured so that a voltage is applied between the terminals of the motor 3 with a phase delayed from the phase calculated by the speed detection unit 14. , 31,..., 35 are individually turned on / off to perform delayed phase braking. As a result, the control unit 16 stops the rotation of the motor 3.
The control unit 16 corresponds to a receiving unit in the claims.

  3 and 4 are flowcharts showing the procedure of operations executed by the control unit 16. The control unit 16 starts operation from a state in which the motor drive device 1 is activated by a power switch (not shown).

  First, the control part 16 determines whether the rotation instruction | indication of the motor 3 was received from the switch 4 (step S1). When it determines with the control part 16 not receiving the rotation instruction | indication of the motor 3 (step S1: NO), the rotation speed detected by the speed detection part 14 is read (step S2). Thereby, the control part 16 recognizes the rotational speed of the motor 3 rotating by external force.

  Next, the control unit 16 determines whether or not the rotation speed read in step S1 is less than N1 (step S3). When it is determined that the rotation speed is equal to or higher than N1 (step S3: NO), the control unit 16 performs delayed phase braking (step S4). When it is determined that the rotation speed is less than N1 (step S3: YES), the controller 16 performs short-circuit braking (step S5). The control unit 16 continues to perform short-circuit braking or delayed phase braking until an instruction to rotate the motor 3 is received.

  When it determines with the control part 16 having received the rotation instruction | indication of the motor 3 (step S1: YES), the rotation speed detected by the speed detection part 14 is read (step S6). Thereby, before starting the rotation of the motor 3, the control part 16 recognizes the rotational speed of the motor 3 rotating in conjunction with the rotating object by external force.

  Next, the control unit 16 determines whether or not the rotation speed read in step S6 is less than N2 (step S7). When it is determined that the rotation speed is N2 or higher (step S7: NO), the control unit 16 performs delayed phase braking (step S8), and returns the process to step S6. The controller 16 continues the delayed phase braking until the rotational speed of the motor 3 detected by the speed detector 14 becomes less than N2.

When the control unit 16 determines that the rotation speed is less than N2 (step S7: YES), the FETs 30, 31,..., 35 are turned on / off separately, and between the inverter 13 and the motor 3 terminals, The rotation of the motor 3 is started by applying a pulse voltage corresponding to the AC voltage (step S9).
Here, the control unit 16 rotates the motor 3 at the rotation speed stored in the storage unit 15.

  Further, since the rotation of the motor 3 is started in a state where the rotation of the motor 3 is stopped by the short-circuit braking and / or the delayed phase braking or the rotation speed of the motor 3 is sufficiently slow, the rotation of the motor 3 is started. The induced voltage generated by is low, and the application of the induced voltage does not damage the components in the motor drive device 1.

  After executing Step S9, the control unit 16 determines whether or not a stop instruction has been received from the switch 4 (Step S10). When it determines with the control part 16 not receiving the stop instruction | indication (step S10: NO), it repeats the determination of step S10, and continues rotating the motor 3 until a stop instruction | indication is received.

  When it is determined that the stop instruction has been received (step S10: YES), the control unit 16 applies a pulse voltage corresponding to the AC voltage with a delayed energization phase between the inverter 13 and the motor 3 to rotate the motor 3. By braking, the rotation of the motor 3 is stopped (step S11). After executing Step S11, the control unit 16 ends the operation and executes the operation from Step S1 again.

  In the present embodiment, the control unit 16 prevents the rotation of the motor 3 by adjusting the pulse voltage applied from the inverter 13 to the terminal of the motor 3 when the inverter 13 performs delayed phase braking. The torque acting in the direction can be adjusted. Furthermore, when the rotational speed of the motor 3 becomes less than N1 and becomes sufficiently small, the rotation of the motor 3 is braked by a short circuit between the terminals of the motor 3. Therefore, the motor driving device 1 can brake the rotation of the motor 3 due to the external force with an appropriate torque and decelerate quickly.

  The control unit 16 reads the rotation speed of the motor 3, determines whether the rotation speed is less than N2, and does not perform delayed phase braking when receiving a rotation instruction from the switch 4. 3 rotations may be started. At this time, in the procedure of the operation executed by the control unit 16 shown in FIGS. 3 and 4, when the control unit 16 determines that the rotation instruction is received in step S1, the control unit 16 executes step S9.

  Normally, the rotation speed of the motor 3 is sufficiently slowed by the short-circuit braking and / or the delayed phase braking performed by the control unit 9 while the control unit 16 receives the rotation instruction of the motor 3 after the motor driving device 1 is activated. Yes. For this reason, even if the control part 16 receives the rotation instruction | indication of the motor 3 from the switch 4, even if it starts rotation of the motor 3, the induced voltage which generate | occur | produces with the start of rotation of the motor 3 is small enough, 3 is prevented from being damaged.

  The motor 3 is not limited to a three-phase brushless DC motor, and may be a two-phase or four-phase or more brushless DC motor, and is not limited to a brushless DC motor.

  Further, the rotational speed N1 is not limited to the rotational speed at which the torque generated in the motor 3 by the short circuit braking is maximized. Even in this case, the motor driving device 1 can perform the braking of the rotation of the motor 3 with an appropriate torque and the rapid deceleration of the rotation of the motor 3 with low power consumption. Re-acceleration is not performed by an external force, and the state where the rotation of the motor 3 is decelerated or stopped is maintained.

  Further, each of the FETs 30, 31,..., 35 is not limited to an N channel type FET, and may be a P channel type FET. Further, since each of the FETs 30, 31,..., 35 may be a semiconductor switch, it may be a bipolar transistor.

  The disclosed embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Motor drive device 14 Speed detection part 16 Control part 3 Motor Lu, Lv, Lw Coil N1, N2 Rotational speed

Claims (2)

In a motor driving device that drives the motor by applying a voltage between terminals of the motor,
Receiving means for receiving a rotation instruction of the motor;
A detection unit for detecting the rotational speed of the motor,
When the receiving means has not received a rotation instruction and the rotation speed detected by the detection unit is less than a first speed, the terminals are short-circuited, and the rotation speed detected by the detection unit is when it is first speed or more, Ri configured tear to apply a voltage between the terminals so that the torque is generated in the direction to prevent the rotation of said motor,
The first speed is a rotational speed at which a torque generated in the motor due to a short circuit between the terminals is maximized,
Torque generated in the direction that prevents the rotation when the rotational speed is the first speed, it is substantially coincides with the torque generated by the short circuit between the terminals when the rotational speed is the first speed The motor drive device characterized by the above-mentioned. When the receiving means receives a rotation instruction and the rotation speed detected by the detection unit is equal to or higher than a second speed, a voltage is applied across the terminals so that torque is generated in a direction that prevents the rotation. The motor driving device according to claim 1, wherein the motor driving device is configured to start rotation when the rotation speed applied and detected by the detection unit is less than a second speed.

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