CN114270648A

CN114270648A - Motor driving circuit

Info

Publication number: CN114270648A
Application number: CN202080059027.1A
Authority: CN
Inventors: 青山宏文; 上田贵哉
Original assignee: Hi Lex Corp
Current assignee: Hi Lex Corp
Priority date: 2019-08-30
Filing date: 2020-08-28
Publication date: 2022-04-01
Also published as: JP2021040371A; JP7237777B2; WO2021039937A1

Abstract

The motor drive circuit includes: a motor; a battery for supplying electric power to the motor; a power supply wiring line to which a battery voltage is supplied and which is connected to the motor; a fifth FET that is connected to the power supply wiring when a voltage is applied thereto and is disconnected from the power supply wiring when no voltage is applied thereto; a motor driver that controls driving of the motor and is capable of applying a voltage to the fifth FET; a voltage application wiring connecting the motor driver and the fifth FET; and a detection circuit capable of detecting a reverse voltage generated in the motor and a battery voltage of a battery connected to the power supply wiring, wherein the detection circuit cuts off a voltage applied to the fifth FET through the voltage application wiring when the reverse voltage of the motor is detected when the battery is not connected to the power supply wiring, and by using the motor drive circuit, even if the reverse voltage is generated in the motor when the battery is not connected to the drive circuit of the motor, the output of the reverse voltage to the battery connection portion side of the power supply path can be suppressed.

Description

Motor driving circuit

Technical Field

The present invention relates to a motor drive circuit.

Background

Conventionally, as a drive circuit of an actuator such as a motor, there is a drive circuit configured to include a power supply terminal connected to a positive terminal of a battery and to operate the battery as a power supply.

In a drive circuit that operates using power from a battery, in order to prevent a current from flowing from the drive circuit side to the power supply terminal side when the battery is reversely connected with the negative terminal of the battery connected to the power supply terminal of the drive circuit, an FET (Field effect transistor) is provided in a power supply path connecting the power supply terminal and the drive circuit (see patent document 1).

In the drive circuit in which the FET is provided in the power supply path, when the battery is normally connected, a potential difference is generated between the gate and the source of the FET, and the FET is turned on, so that the power supply path is connected, and power can be supplied from the battery to the drive circuit.

On the other hand, when the battery is connected in reverse to the drive circuit, the gate and the source of the FET are held at the same potential, and the FET is turned off, so that the power supply path is disconnected, and a current is prevented from flowing from the drive circuit side to the power supply terminal side in the power supply path. An electronic control device other than a drive circuit in which an actuator is connected to a power supply terminal can suppress an influence on the operation of the other electronic control device by blocking a current from flowing to the power supply terminal side.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2007-82374

Disclosure of Invention

Problems to be solved by the invention

In the case where the above-described drive circuit is a drive circuit for driving a motor, a reverse voltage is generated in the motor at the time of starting and stopping the motor. For example, when a battery is not connected to the drive circuit, when a reverse voltage is generated in the motor, the generated back electromotive force is applied to the gate of the FET, and the FET is turned on. When the FET is turned on, a power supply path is connected, and a reverse voltage of the motor is output to the power supply terminal side, which may affect the operation of other electronic control devices.

The invention aims to provide a drive circuit of a motor, which can restrain the generated reverse voltage from outputting to the battery connecting part side of a power supply path even if the motor generates the reverse voltage.

Means for solving the problems

The motor drive circuit for solving the above problems has the following features.

That is, the motor drive circuit of the present invention includes: a motor; a battery that supplies electric power to the motor; a power supply path to which a battery voltage of the battery is supplied and which is connected to the motor; a power supply switching unit provided on the power supply path, the power supply switching unit connecting the power supply path when a voltage is applied and disconnecting the power supply path when a voltage is not applied; a control section including: a drive control unit connected to the motor and controlling driving of the motor; and a voltage applying unit connected to the power supply switching unit and capable of applying a voltage to the power supply switching unit; a voltage application path connecting the control unit and the power supply switching unit; and a detection circuit provided in the voltage application path and capable of detecting a reverse voltage generated in the motor, the detection circuit cutting off a voltage applied to the power supply switching unit through the voltage application path when the reverse voltage of the motor is detected.

Effects of the invention

According to the present invention, since no voltage is applied to the power supply switching means when the motor generates a reverse voltage, the power supply switching means disconnects the power supply path, and the generated reverse voltage is not output to the battery connection portion side of the power supply path. This can suppress an influence on the operation of another electronic control device connected to the power supply path.

Drawings

Fig. 1 is a perspective view showing a vehicle provided with a motor drive circuit.

Fig. 2 is a side view showing a vehicle provided with a motor drive circuit.

Fig. 3 is a circuit diagram of a motor drive circuit.

Detailed Description

Next, a mode for carrying out the present invention will be described with reference to the drawings.

[ approximate structures of opening/closing body drive section and motor drive device ]

The motor drive circuit 3 shown in fig. 1 to 3 is an embodiment of the motor drive circuit of the present invention, and is provided in a vehicle 10. The vehicle 10 includes a vehicle body 11 having an opening 11a, a rear door 12 serving as an opening/closing body for opening/closing the opening 11a of the vehicle body 11, an opening/closing body driving unit 20 for opening/closing and driving the rear door 12, and the motor driving circuit 3 is provided in the opening/closing body driving unit 20. The motor drive circuit 3 has a motor 30 as a drive source for driving the rear door 12 to open and close.

The opening 11a is located at the rear of the vehicle body 11. The upper end portion of the rear door 12 is rotatably supported by the vehicle body 11 via a hinge, and the rear door 12 is movable between a closed position (a position indicated by a solid line in fig. 2) for closing the opening portion 11a and an open position (a position indicated by a two-dot chain line in fig. 2) for opening the opening portion 11a by rotating about the upper end portion. The opening/closing body driving unit 20 may be provided at, for example, both left and right end portions of the rear portion of the vehicle 10, but may be provided only at one of the left and right end portions.

The motor 30 in the motor drive circuit 3 is not limited to a drive source for opening and closing the rear door 12 of the vehicle 10, and may be used as a drive source for opening and closing a shutter door, a sliding door, a hinge door, and the like provided in a structure such as a store or a garage, and a drive source for opening and closing a toilet lid for driving a toilet stool. The motor 30 may be used as a driving source of various driving devices for rotating or moving an article or a structure to be driven in the vertical direction, the horizontal direction, and the oblique direction.

The opening/closing body drive unit 20 includes a main body tube 21, a slide tube 22, and a motor drive circuit 3.

One end side of the main body tube portion 21 is rotatably supported by the vehicle 10, and the other end side is open. The sliding cylinder portion 22 is supported on the other end portion side of the main body cylinder portion 21 so as to be slidable in the longitudinal direction with respect to the main body cylinder portion 21. The slide cylinder portion 22 is slidable in the longitudinal direction with respect to the main body cylinder portion 21, and is movable forward and backward with respect to the main body cylinder portion 21.

A main shaft (not shown) supported rotatably about an axis and a motor 30 for rotationally driving the main shaft are disposed inside the main body tube 21. A spindle nut (not shown) fixed to the slide cylinder portion 22 and screwed to the spindle is provided inside the slide cylinder portion 22.

The spindle nut is moved along the longitudinal direction of the main body cylinder 21 by the spindle being rotationally driven by the motor 30. Thereby, the slide cylinder portion 22 moves forward and backward with respect to the main body cylinder portion 21. In this case, for example, when the motor 30 rotates in one of the normal and reverse rotation directions, the slide cylinder portion 22 housed inside the main body cylinder portion 21 advances from the opening of the main body cylinder portion 21, and when the motor 30 rotates in the other of the normal and reverse rotation directions, the slide cylinder portion 22 retreats inside the main body cylinder portion 21.

In this way, by the sliding tube portion 22 moving forward and backward with respect to the main tube portion 21, the rear door 12 moves in the direction of opening and closing the opening 11a in accordance with the length of the sliding tube portion 22 advancing from the main tube portion 21. Specifically, when the sliding cylinder portion 22 moves in the forward direction from the main body cylinder portion 21, the rear door 12 moves in the direction of opening the opening portion 11a, and when the sliding cylinder portion 22 moves in the retracting direction with respect to the main body cylinder portion 21, the rear door 12 moves in the direction of closing the opening portion 11 a. That is, the motor 30 drives the driving target (the rear door 12 in the present embodiment) by driving.

The vehicle 10 has a battery 6 as a dc power supply, and the motor 30 is a dc motor driven by the battery 6. However, the motor 30 may be an ac motor driven by an ac power supply.

[ Structure of Motor drive Circuit ]

As shown in fig. 3, the motor drive circuit 3 includes a motor 30, a battery 6 that supplies power to the motor 30, a power supply wiring 51 to which a battery voltage of the battery 6 is supplied, a ground wiring 52 to which a voltage having a lower potential than the battery voltage of the battery 6 is supplied, and a motor driver 81 as a drive control unit that controls driving of the motor 30. The motor 30 has a first terminal 30a and a second terminal 30 b. One end of the power supply wiring 51 has a power supply terminal VB1 connected to the positive terminal of the battery 6, and the other end of the power supply wiring 51 is connected to the motor 30. The power supply wiring 51 is an example of a power supply path. The ground wiring 52 is an example of a ground path, and is grounded in the present embodiment.

The motor drive circuit 3 has a first FET31, a second FET32, a third FET33, a fourth FET34, and a fifth FET 35. The first FET31, the second FET32, the third FET33, the fourth FET34, and the fifth FET35 are N-channel MOSFETs, respectively.

The first FET31 is connected between the power supply wiring 51 and the first terminal 30a of the motor 30. That is, the power supply wiring 51 and the first terminal 30a of the motor 30 are connected via the first FET 31. In this case, the first drain 31D of the first FET31 is connected to the power supply line 51, and the first source 31S of the first FET31 is connected to the first terminal 30a of the motor 30. The first FET31 exemplifies a first switching element. The first FET31 has a first parasitic diode D1 whose cathode is connected to the fifth FET35 side and whose anode is connected to the motor 30 side.

The second FET32 is connected between the second terminal 30b of the motor 30 and the ground wiring 52. That is, the second terminal 30b of the motor 30 and the ground wiring 52 are connected via the second FET 32. In this case, the second drain 32D of the second FET32 is connected to the second terminal 30b of the motor 30, and the second source 32S of the second FET32 is connected to the ground wiring 52. The second FET32 exemplifies a second switching element. The second FET32 has a second parasitic diode D2 whose cathode is connected to the motor 30 side and whose anode is connected to the ground wiring 52 side.

The third FET33 is connected between the power supply wiring 51 and the second terminal 30b of the motor 30. That is, the power supply wiring 51 and the second terminal 30b of the motor 30 are connected via the third FET 33. In this case, the third drain 33D of the third FET33 is connected to the power supply wiring 51, and the third source 33S of the third FET33 is connected to the second terminal 30b of the motor 30. The third FET33 is an example of a third switching unit. The third FET33 has a third parasitic diode D3 whose cathode is connected to the fifth FET35 side and whose anode is connected to the motor 30 side.

The fourth FET34 is connected between the first terminal 30a of the motor 30 and the ground wiring 52. That is, the first terminal 30a of the motor 30 and the ground wiring 52 are connected via the fourth FET 34. In this case, the fourth drain 34D of the fourth FET34 is connected to the first terminal 30a of the motor 30, and the fourth source 34S of the fourth FET34 is connected to the ground wiring 52. The fourth FET34 is an example of a fourth switching means. The fourth FET34 has a fourth parasitic diode D4 whose cathode is connected to the motor 30 side and whose anode is connected to the ground wiring 52 side.

The fifth FET35 is provided on the power supply wiring 51. Specifically, the power supply terminal VB1 is connected to the power supply wiring 51, and the first FET31 and the third FET33 are connected. In this case, the fifth source 35S of the fifth FET35 is connected to the power supply line 51 on the power supply terminal VB1 side, and the fifth drain 35D of the fifth FET35 is connected to the power supply line 51 on the first FET31 and the third FET33 sides. The fifth FET35 is an example of a power supply switching means. The fifth FET35 has a fifth parasitic diode D5 whose cathode is connected to the first FET31 and the third FET33, and whose anode is connected to the power supply terminal VB 1.

The motor driver 81 has a first terminal 81a, a second terminal 81b, a third terminal 81c, a fourth terminal 81d, a fifth terminal 81e, and a sixth terminal 81 f.

The first terminal 81a is connected to the first gate 31G of the first FET31, and the motor driver 81 is configured to be able to apply a voltage greater than the threshold voltage of the first FET31 from the first terminal 81a to the first gate 31G. The first FET31 is turned on when a voltage greater than the threshold voltage is applied from the first terminal 81a of the motor driver 81 to the first gate 31G, and the first drain 31D and the first source 31S are connected. On the other hand, when no voltage is applied from the first terminal 81a of the motor driver 81 to the first gate 31G, the first FET31 turns off, and the first drain 31D and the first source 31S are disconnected from each other.

The second terminal 81b is connected to the second gate 32G of the second FET32, and the motor driver 81 is configured to be able to apply a voltage greater than the threshold voltage of the second FET32 from the second terminal 81b to the second gate 32G. When a voltage greater than the threshold voltage is applied from the second terminal 81b of the motor driver 81 to the second gate 32G, the second FET32 turns on, and the second drain 32D and the second source 32S are connected. On the other hand, the second FET32 turns off when no voltage is applied to the second gate 32G from the second terminal 81b of the motor driver 81, and the second drain 32D and the second source 32S are disconnected.

The third terminal 81c is connected to the third gate 33G of the third FET33, and the motor driver 81 is configured to be able to apply a voltage greater than the threshold voltage of the third FET33 from the third terminal 81c to the third gate 33G. When a voltage greater than the threshold voltage is applied from the third terminal 81c of the motor driver 81 to the third gate 33G, the third FET33 turns on, and the third drain 33D is connected to the third source 33S. On the other hand, the third FET33 turns off when no voltage is applied to the third gate 33G from the third terminal 81c of the motor driver 81, and the third drain 33D and the third source 33S are disconnected.

The fourth terminal 81d is connected to the fourth gate 34G of the fourth FET34, and the motor driver 81 is configured to be able to apply a voltage greater than the threshold voltage of the fourth FET34 from the fourth terminal 81d to the fourth gate 34G. The fourth FET34 is turned on when a voltage greater than the threshold voltage is applied from the fourth terminal 81D of the motor driver 81 to the fourth gate 34G, and the fourth drain 34D and the fourth source 34S are connected. On the other hand, the fourth FET34 turns off when no voltage is applied to the fourth gate 34G from the fourth terminal 81D of the motor driver 81, and the fourth drain 34D and the fourth source 34S are disconnected.

In the motor drive circuit 3, a bridge circuit BC for driving the motor 30 is configured by the first FET31, the second FET32, the third FET33, and the fourth FET 34. The bridge circuit BC is an example of a bridge circuit for driving the motor.

The motor drive circuit 3 has a voltage application wiring 53 connecting the fifth terminal 81e and the fifth gate 35G of the fifth FET35, and the motor driver 81 is configured to be able to apply a voltage greater than the threshold voltage of the fifth FET35 from the fifth terminal 81e to the third gate 33G through the voltage application wiring 53.

The fifth FET35 is turned on when a voltage greater than the threshold voltage is applied from the fifth terminal 81e of the motor driver 81 to the fifth gate 35G, and the fifth drain 35D and the fifth source 35S are connected. On the other hand, the fifth FET35 turns off when no voltage is applied to the fifth gate 35G from the fifth terminal 81e of the motor driver 81, and the fifth drain 35D and the fifth source 35S are disconnected.

The motor drive circuit 3 has a connection wiring 54. One end of the connection wiring 54 is connected to the power supply wiring 51, and the other end is connected to the sixth terminal 81 f. One end of the connection wiring 54 is connected between the fifth FET35 on the power supply wiring 51 and the first FET31 and the third FET33 of the bridge circuit BC. A drive terminal VM1 to which a drive voltage for driving the motor driver 81 is supplied is connected between the fifth FET35 and the first FET31 and the third FET33 of the bridge circuit BC on the power supply wiring 51. The drive terminal VM1 is connected to the sixth terminal 81f of the motor driver 81 through the connection wiring 54. The drive terminal VM1 is an example of a control unit drive terminal. The connection wiring 54 is an example of a connection path. The motor drive circuit 3 has a voltage applying section that applies a voltage to the power supply switching means.

The motor drive circuit 3 includes a short-circuit transistor 37 connected between the fifth gate 35G and the fifth source 35S of the fifth FET 35. A diode 38 is connected between the short-circuiting transistor 37 and the fifth source 35S. The short-circuit transistor 37 is an NPN transistor, and has a base B grounded, a collector C connected to the fifth gate 35G, and an emitter E connected to the fifth source 35S. The short-circuit transistor 37 is turned on when the voltage of the base B is higher than the voltage of the emitter E by a predetermined value or more, and is turned off when the voltage of the base B is not higher than the voltage of the emitter E by a predetermined value or more. The diode 38 has a cathode connected to the fifth source 35S side and an anode connected to the fifth gate 35G side.

When the positive terminal of the battery 6 is connected to the power supply terminal VB1 or when the battery 6 is not connected to the power supply terminal VB1, the voltage of the base B of the short-circuiting transistor 37 is not higher than the voltage of the emitter E by a predetermined value or more, and the short-circuiting transistor 37 is turned off. When the short-circuit transistor 37 is turned off, the collector C and the emitter E are disconnected, and no current flows between the fifth gate 35G and the fifth source 35S of the fifth FET 35.

On the other hand, when the negative terminal of the battery 6 is connected to the power supply terminal VB1, the voltage of the base B of the short-circuiting transistor 37 is higher than the voltage of the emitter E by a predetermined value or more, and the short-circuiting transistor 37 is turned on. When the short-circuit transistor 37 is on, the collector C and the emitter E are on, and the fifth gate 35G and the fifth source 35S of the fifth FET35 are short-circuited. In this case, since the diode 38 is connected between the fifth gate 35G and the fifth source 35S, a current flows from the fifth gate 35G to the fifth source 35S, but a current does not flow from the fifth source 35S to the fifth gate 35G.

The motor drive circuit 3 has a detection circuit 7. The detection circuit 7 is provided on the voltage application wiring 53, and has a first transistor 71 and a second transistor 72. The first transistor 71 is an example of a first circuit, and the second transistor 72 is an example of a second circuit. The detection circuit 7 may be configured to be provided with a detection unit that detects a battery voltage of a battery connected to the power supply path.

The first transistor 71 is an NPN transistor, and has a first base B1 connected to the reverse voltage input terminal VM2, a first collector C1 connected to the voltage application wiring 53, and a first emitter E1 connected to ground. The first base B1 is an example of a first input terminal of the first transistor, the first collector C1 is an example of a first output terminal of the first transistor, and the first emitter E1 is an example of a first ground terminal of the first transistor. The reverse voltage input terminal VM2 is a terminal to which a reverse voltage generated in the motor 30 is input.

The first transistor 71 is turned on when a reverse voltage of the motor 30 is input to the first base B1 via the reverse voltage input terminal VM2, and the first collector C1 is turned on with the first emitter E1. The first collector C1 is electrically connected to the first emitter E1, and the voltage application wiring 53 is grounded. In addition, the first transistor 71 is turned off when the reverse voltage of the motor 30 is not input to the first base B1, and the first collector C1 is disconnected from the first emitter E1. In a state where the first collector C1 is disconnected from the first emitter E1, the voltage-application wiring 53 is not grounded.

The second transistor 72 is an NPN transistor, the second base B2 is connected to the battery voltage input terminal VB2, the second collector C2 is connected to the first base B1 of the first transistor 71, and the second emitter E2 is grounded. The second base B2 is an example of a second input terminal of the second transistor, the second collector C2 is an example of a second output terminal of the second transistor, and the second emitter E2 is an example of a second ground terminal of the second transistor.

The battery voltage input terminal VB2 is a terminal to which the battery voltage of the battery 6 is input. The battery voltage is input to the battery voltage input terminal VB2 when the positive electrode terminal of the battery 6 is connected to the power supply terminal VB1, and is not input to the battery voltage when the positive electrode terminal of the battery 6 is not connected to the power supply terminal VB 1.

The second transistor 72 is turned on when the battery voltage of the battery 6 is input to the second base B2 via the battery voltage input terminal VB2, the second collector C2 is turned on with the second emitter E2, and the first base B1 of the first transistor 71 is grounded. In a state where the first base B1 is grounded, even in a case where a reverse voltage of the motor 30 is applied to the reverse voltage input terminal VM2, the input of the reverse voltage to the first transistor 71 is blocked, and the first transistor 71 maintains an off state.

The second transistor 72 is turned off when the battery voltage is not input to the second base B2, and the second collector C2 is disconnected from the second emitter E2. In a state where the second collector C2 is disconnected from the second emitter E2, the first base B1 of the first transistor 71 is not grounded, allowing the input of the reverse voltage of the motor 30, which is applied to the reverse voltage input terminal VM2, to the first base B1.

The motor drive circuit 3 includes a plurality of ECUs (Electronic Control units) 82 and 83 that Control operations of each part of the vehicle 10. The ECUs 82, 83 are connected between a power supply terminal VB1 on the power supply wiring 51 and the fifth FET 35. The ECUs 82, 83 can be configured to control operations of an engine, a transmission, a brake, a power window, various instruments, and the like of the vehicle 10.

[ operation of Motor drive Circuit ]

In the motor drive circuit 3 configured as described above, in a normal state in which the positive terminal of the battery 6 is connected to the power supply terminal VB1 and the battery voltage is supplied to the power supply wiring 51, a boosted voltage for boosting the battery voltage is applied from the fifth terminal 81e of the motor driver 81 to the fifth gate 35G of the fifth FET 35. In this case, since the battery voltage is input to the battery voltage input terminal VB2 in the detection circuit 7, the first transistor 71 is turned off, and the short-circuit transistor 37 is turned off, the boosted voltage output from the fifth terminal 81e is allowed to be applied to the fifth gate electrode 35G through the voltage application wiring 53.

The boosted voltage is higher than the threshold voltage of the fifth FET35, and when the boosted voltage is applied to the fifth gate 35G, the fifth FET35 is turned on, and power from the battery 6 can be supplied to the motor 30.

In this state, when the first terminal 81a and the second terminal 81b of the motor driver 81 output voltages applied to the first gate 31G and the second gate 32G, the first FET31 and the second FET32 are turned on, and the third FET33 and the fourth FET34 are held in an off state, a current flows from the first FET31 to the second FET32 via the motor 30, and the motor 30 rotates in the normal rotation direction.

On the other hand, when the voltage applied to the third gate 33G and the fourth gate 34G is output from the third terminal 83a and the fourth terminal 84b of the motor driver 81, the third FET33 and the fourth FET34 are turned on, and the first FET31 and the second FET32 are held in the off state, a current flows from the third FET33 to the fourth FET34 via the motor 30, and the motor 30 rotates in the reverse direction.

In addition, when the power supply terminal VB1 is connected to the negative terminal of the battery 6, the short-circuit transistor 37 is turned on to short-circuit the fifth gate 35G and the fifth source 35S of the fifth FET35, and therefore, a voltage larger than the threshold voltage is not applied to the fifth gate 35G of the fifth FET35, and the fifth FET35 is turned off.

Here, although a reverse voltage is generated in the motor 30 at the time of starting and stopping, the cathodes of the first parasitic diode D1 of the first FET31 and the third parasitic diode D3 of the third FET33 connected to the motor 30 are connected to the fifth FET35 side, and thus the generated reverse voltage is input to the power supply wiring 51 through the first parasitic diode D1 and the third parasitic diode D3.

However, since the fifth FET35 is turned off and the anode of the fifth parasitic diode D5 of the fifth FET35 is connected to the power supply terminal VB1 side, the reverse voltage input to the power supply wiring 51 is not output to the power supply terminal VB1 side with respect to the fifth FET 35. Thus, the reverse voltage of the motor 30 is not applied to the ECUs 82 and 83 connected between the power supply terminal VB1 on the power supply wiring 51 and the fifth FET35, and the influence on the operations of the ECUs 82 and 83 can be suppressed.

When the battery 6 is not connected to the power supply terminal VB1, if a reverse voltage is generated in the motor 30, the generated reverse voltage is input to the power supply wiring 51 through the first parasitic diode D1 and the third parasitic diode D3. The reverse voltage input to the power supply wiring 51 is input to the motor driver 81 through the connection wiring 54 and the sixth terminal 81f, and the reverse voltage input to the motor driver 81 is further output to the voltage application wiring 53 from the fifth terminal 81 e.

In this case, when the reverse voltage output to the voltage application wiring 53 is applied to the fifth gate 35G of the fifth FET35, since the reverse voltage is greater than the threshold voltage of the fifth FET35, the fifth FET35 is turned on and the reverse voltage output to the power supply wiring 51 is applied to the ECUs 82, 83.

However, when the battery 6 is not connected to the power supply terminal VB1, if a reverse voltage is generated in the motor 30, the reverse voltage is input to the reverse voltage input terminal VM2 in a state where the second transistor 72 is off, and therefore the reverse voltage is input to the first base B1 from the reverse voltage input terminal VM2 and the first transistor 71 is turned on. When the first transistor 71 is turned on, the voltage application wiring 53 is grounded, and the reverse voltage output to the voltage application wiring 53 is not applied to the fifth gate 35G of the fifth FET 35.

That is, when the reverse voltage of the motor 30 is detected by the detection circuit 7 while the power supply wiring 51 is not connected to the battery 6, the reverse voltage applied to the fifth gate 35G of the fifth FET35 through the voltage application wiring 53 is cut off, and the fifth FET35 is turned off. Accordingly, by disconnecting the power supply wiring 51 with the fifth FET35, the reverse voltage output to the power supply wiring 51 is not output to the ECUs 82 and 83, and the influence on the operations of the ECUs 82 and 83 is suppressed.

In this way, the first transistor 71 of the detection circuit 7 is configured to cut off the voltage applied to the fifth FET35 when the reverse voltage of the motor 30 is input, and to allow the voltage applied to the fifth FET35 when the reverse voltage of the motor 30 is not input. The second transistor 72 of the detection circuit 7 is configured to block the input of the reverse voltage to the first transistor 71 when the battery voltage of the battery 30 is input, and to allow the input of the reverse voltage to the first transistor 71 when the battery voltage of the battery 30 is not input.

Therefore, when the battery 6 is not connected to the power supply wiring 51, the reverse voltage is allowed to be input to the first transistor 71 through the second transistor 72, and in the case where the reverse voltage is generated in the motor 30 in this state, the voltage applied to the fifth FET35 is cut off through the first transistor 71. Accordingly, the fifth FET35 disconnects the power supply wiring 51, and the reverse voltage is not output to the power supply wiring 51 on the power supply terminal VB1 side of the fifth FET 35.

Further, since the detection circuit 7 is configured by the first transistor 71 and the second transistor 72, the detection circuit 7 can have a simple circuit configuration.

Further, the motor drive circuit 3 includes: a bridge circuit BC having a first FET31, a second FET32, a third FET33, and a fourth FET34 and driving the motor 30; and a drive terminal VM1 provided between the fifth FET35 on the power supply wiring 51 and the bridge circuit BC, and supplied with a drive voltage of the motor driver 81.

In such a configuration, when the motor driver 81 and the fifth FET35 are connected via the voltage application wiring 53, a reverse voltage generated in the motor 30 driven by the bridge circuit BC is applied to the fifth FET35 via the connection wiring 54, the motor driver 81, and the voltage application wiring 53.

However, when a reverse voltage is generated in the motor 30 in a state where the battery 6 is not connected to the power supply wiring 51, the voltage detection circuit 7 is turned off, and therefore, the reverse voltage is not applied to the fifth FET 35. Thus, the fifth FET35 disconnects the power supply wiring 51, and the generated reverse voltage is not output to the power supply terminal VB1 side of the power supply wiring 51, thereby suppressing an influence on the operation of the ECUs 82 and 83 connected to the power supply wiring 51.

In particular, the motor 30 of the present embodiment is a drive source for opening and closing the rear door 12 of the vehicle 10. Therefore, when a reverse voltage is generated in the motor 30 in a state where the battery 6 is not connected to the power supply wiring 51, the generated reverse voltage is not output to the power supply terminal VB1 side of the power supply wiring 51, and it is possible to suppress an influence on the operations of the ECUs 82 and 83 as control devices of other in-vehicle devices connected to the power supply wiring 51.

The first FET31, the second FET32, the third FET33, and the fourth FET34 constituting the bridge circuit BC may be constituted by physical relay switches. In this case, it is preferable that diodes similar to the first parasitic diode D1, the second parasitic diode D2, the third parasitic diode D3, and the fourth parasitic diode D4 be provided in parallel to the relay switches. By providing the relay switch with a diode, when the motor 30 generates a reverse voltage, a current caused by the reverse voltage of the motor 30 can be discharged through the diode, thereby suppressing the occurrence of breakage in the relay switch.

In the vehicle 10, as the opening/closing body using the motor 30 as a drive source, a trunk lid, an engine hood, a sunroof, a slide door, a door mirror, a window glass related to a fan or provided in a door, or the like can be applied in addition to the rear door 12.

Description of the reference symbols

1 an opening/closing body opening/closing device;

3a motor drive circuit;

6 a motor;

7 a detection circuit;

10 a vehicle;

11a vehicle body;

11a opening part;

12 a rear door;

20 an opening/closing body driving unit;

21 a main body tube part;

22 a sliding cylinder part;

30 motor;

30a first terminal;

30b a second terminal;

31 a first FET;

31D a first drain electrode;

a 31G first gate;

a 31S first source;

32 a second FET;

a 32D second drain electrode;

a 32G second gate;

a 32S second source electrode;

33 a third FET;

33D a third drain electrode;

33G third grid;

a 33S third source;

34 a fourth FET;

34D a fourth drain;

34G a fourth grid;

34S fourth source electrode;

35 a fifth FET;

35D a fifth drain electrode;

35G a fifth grid;

35S a fifth source electrode;

37 a transistor for short-circuiting;

38 diodes;

51 power supply wiring;

52 a ground wiring;

53 voltage applying wirings;

54 connection path;

71 a first transistor;

72 a second transistor;

81 motor drivers;

81a first terminal;

81b a second terminal;

81c a third terminal;

81d a fourth terminal;

81e a fifth terminal;

81f a sixth terminal;

82、83ECU；

a BC bridge circuit;

a base electrode B;

c, a collector;

e, an emitter;

a base electrode B;

a C1 first collector electrode;

e1 first emitter;

b2 second base;

a C2 second collector electrode;

e2 second emitter;

d1 first parasitic diode;

d2 second parasitic diode;

d3 third parasitic diode;

d4 fourth parasitic diode;

d5 fifth parasitic diode;

a VB1 power supply terminal;

a VB2 battery voltage input terminal;

VM1 drive terminals;

VM2 reverses the voltage input terminals.

Claims

1. A motor drive circuit includes:

a motor;

a battery that supplies electric power to the motor;

a power supply path to which a battery voltage of the battery is supplied and which is connected to the motor;

a power supply switching unit provided on the power supply path, the power supply switching unit connecting the power supply path when a voltage is applied and disconnecting the power supply path when a voltage is not applied;

a control section including: a drive control unit connected to the motor and controlling driving of the motor; and a voltage applying unit connected to the power supply switching unit and capable of applying a voltage to the power supply switching unit;

a voltage application path connecting the control unit and the power supply switching unit; and

a detection circuit provided on the voltage application path and capable of detecting a reverse voltage generated in the motor,

the detection circuit cuts off the voltage applied to the power supply switching unit through the voltage application path when detecting a reverse voltage of the motor.

2. The motor drive circuit according to claim 1,

the detection circuit has:

a first circuit that cuts off the voltage applied to the power supply switching unit when the reverse voltage of the motor is input, and allows the application of the voltage to the power supply switching unit when the reverse voltage of the motor is not input; and

a second circuit that blocks input of the reverse voltage to the first circuit when the battery voltage of the battery is input, and allows input of the reverse voltage to the first circuit when the battery voltage of the battery is not input.

3. The motor drive circuit according to claim 2, wherein,

the first circuit is a first transistor having: a first input terminal to which a reverse voltage of the motor is input; a first output terminal connected to the power supply path; and a first ground terminal to be grounded,

the second circuit is a second transistor having: a second input terminal to which a battery voltage of the battery is input; a second output terminal connected to the first input terminal of the first transistor; and a second ground terminal that is grounded.

4. The motor drive circuit according to any one of claim 1 to claim 3,

the motor has a first terminal and a second terminal,

the motor drive circuit includes:

a ground path to which a voltage having a lower potential than the battery voltage is supplied;

a bridge circuit having a first switching unit provided between the power supply path and the first terminal, a second switching unit provided between the second terminal and the ground path, a third switching unit provided between the power supply path and the second terminal, and a fourth switching unit provided between the first terminal and the ground path, and configured to drive the motor;

a control unit drive terminal provided between the power supply switching unit and the bridge circuit in the power supply path and supplied with a drive voltage of the control unit; and

and a connection path connecting the control unit drive terminal and the control unit.

5. The motor drive circuit according to any one of claims 1 to 4,

the motor is a driving source for opening and closing a rear door of the vehicle.