JP2003235294A - Driver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a circuit protection at a power source reverse connection time with a small size and a low-cost configuration even when a specification is changed such as a voltage of a power source or the like is changed, in a driver having a bypass line LB for supplying a regenerative current at a motor operating time (at an FET off time) by PWM-driving the motor 1 by a MOSFET 9. <P>SOLUTION: In the driver, a thyristor 24 is connected reversely to the power source voltage on the bypass line LB, a gate current of the thyristor 24 is supplied at a motor 1 drive time of a power source normal time by operating a booster 23 and a peripheral controller 21 to turn on the thyristor 24. At the power source reverse connecting time, a state in which the gate current does not flow is set by operating the booster 23, and the thyristor 24 is maintained off, thereby preventing a large current from flowing at the power source reverse connecting time. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for driving a power window motor of a vehicle, for example.

[0002]

2. Description of the Related Art For example, in order to realize a smooth operation of a power window of a vehicle and a required function (such as a trapping prevention function) at a high level, in addition to the rotation direction of the motor, a rotation speed or an output torque (current). Must be controlled, and a drive system (for example, PWM control system) using a switching element (for example, MOS type FET) that opens and closes the energization line of the motor is indispensable. FIGS. 3A and 3B are diagrams showing an example of a drive device for the motor 1 (DC motor) in the power window system. This drive is shown in FIG.
As shown in (a), a peripheral control unit 2 including a microcomputer and a motor control unit 3 including the switching element are provided. Further, in FIG. 3A, reference numeral 4 indicates a vehicle battery, reference numeral 5 indicates a backflow prevention diode provided in a power supply line to the control unit, and reference numeral 6 indicates a power window operation switch. There is. In addition,
Although there are actually a plurality of operation switches for the power window (for example, as for the driver's seat window, there are generally switches for opening operation, closing operation, and automatic operation), but they are simplified here. . Next, as shown in FIG. 3B, the motor control unit 3 relays 7, 8 for switching the energization state and the rotation direction (energization direction) of the motor 1.
A MOS type FET 9 for PWM controlling the amount of current of the motor 1 and a flywheel diode 10 for flowing a regenerative current. Here, the MOS type FET 9 is
The switching element is connected to the energization line of the motor 1 (in this case, on the ground side energization line) to open and close the energization line. The FET 9 is a control signal A from the control circuit including the microcomputer of the peripheral control unit 2.
Works by. The relays 7 and 8 are also controlled by the peripheral control unit 2 via a relay drive circuit (not shown). In addition, the flywheel diode 10
It is a diode that is connected on a bypass line LB that connects a power supply side energization line and a ground side energization line of the motor 1 so as to allow a regenerative current to flow during motor operation, and is a diode that blocks a forward current with respect to the power supply voltage. .

In this drive device, when the opening / closing operation of the window is instructed by the operation input of the operation switch 6, the control circuit of the peripheral control section 2 causes one of the relays 7 and 8 (the side corresponding to the operating direction of the window). ) Is activated and the control signal A is activated at a predetermined duty ratio to drive the FET 9 on and off at a predetermined duty ratio. Then, one of the coil terminals of the motor 1 is connected to the power supply (the positive electrode of the battery 4), and the other of the coil terminals is connected to the ground via the FET 9, so that a predetermined current flows in the motor 1 and the window becomes a predetermined value. It operates in the direction with a predetermined torque or a predetermined speed. That is, the relays 7 and 8
Alternatively, the operating state of the motor 1, the rotation direction, the output torque, and the like are controlled by the FET 9 (switching element) that opens and closes the energization line of the motor 1. When the FET 9 is off in this motor driving state, a regenerative current flows through the flywheel diode 10 to realize a smooth operation of the motor 1.

By the way, in the motor driving device as described above, when the power source (battery 4 in the device of FIG. 3) is connected, the power source side (the positive side of the power source) and the ground side (the negative side of the power source or the ground potential side). If a power supply reverse connection occurs in which the reverse connection of (1) is reversed, and there is no element that limits the reverse flow of current, in the worst case, a failure such as circuit damage may occur. For example, in the drive device shown in FIGS. 3A and 3B, when the battery 4 is connected in reverse, a large current flows in the reverse direction through the parasitic diode 9a in the FET 9 and the flywheel diode 10. The FET 9 and the flywheel diode 10 may be damaged. Even in the case of a switching element having no parasitic diode, a large current may flow in the reverse direction in the case of a device in which the switching element may turn on in the state where the power source is reversely connected.

Therefore, conventionally, for example, FIG.
As shown in (a) and (b), a fuse or relay that mechanically disconnects the line, or a rectifying element such as a diode that prevents the reverse flow of current is provided on the energization line (in this case, on the power supply side energization line). It was being inserted. Note that FIG. 3 (c) shows a backflow prevention diode 11 connected to the power supply side energization line of the motor 1 in the above-described drive device, and FIG. 4 (a) shows a line interruption to the power supply side energization line. 4B, a fuse 13 for preventing a large current is connected to the power supply side energization line in FIG. 4B. Although the relay 12 in FIG. 4A is controlled so that the line is closed at least when the motor is driven in the normal state, the relay 12 is controlled even when the motor is driven (when the switch is operated) in the power reverse connection state. It is necessary to control 12 to keep it open. Generally, only when the control circuit detects that a proper power supply voltage is being supplied, the relay 1
2 is turned on.

[0006]

However, the conventional drive device which adopts the countermeasure against the reverse connection of the power source as described above has the following problems. That is, in the case of fuses and relays, the effective mounting area on the circuit board on which other components are mounted becomes small due to the size of the electrical performance conditions in the design and the restrictions of mounting holes for mounting on the board. There's a problem. In addition, when a rectifying element such as a diode is inserted in a current-carrying line, a motor current always flows through this element during motor operation, and electrical use conditions become strict, so it is necessary to use a high-performance element. In particular, when specifications such as a rise in power supply voltage occur, the rated performance of relays and diodes used (especially withstand voltage performance)
Therefore, it is necessary to use a larger relay, a diode, or the like in order to improve the cost, and the effective mounting area of other components is further reduced, resulting in an increase in product cost and size. For example, in the field of automobiles, the battery voltage is being increased (changed from the current 12 V to 42 V), and it is expected that high voltage specifications will become common even in popular vehicle models within a few years. In this case, the above-mentioned relays, diodes, etc. for countermeasures against reverse power source connection in a drive device such as a power window are considerably large with high rated performance.

Further, as shown in FIG. 4 (b), when a fuse is provided as a countermeasure against reverse power supply connection, the fuse is blown by reverse connection of the power supply, so that the fuse must be replaced every time. Therefore, the present invention is a drive device having a bypass line for driving a motor with a switching element and flowing a regenerative current when the motor is operating (when the switching element is off), and when there is a change in specifications such as a high power supply voltage. However, it is an object of the present invention to provide a drive device that is compact and inexpensive and that can protect the circuit when the power source is reversely connected and that does not require replacement work such as a fuse.

[0008]

A drive device according to the present invention comprises a switching element which is connected to an energization line of a direct current motor and opens and closes the energization line, and an energization line in the energization line for flowing a regenerative current during operation of the direct current motor. In a drive device having a flywheel diode connected on a bypass line connecting a power supply side and a ground side of the DC motor, a thyristor is connected on the bypass line in a direction opposite to a power supply voltage, and a power supply is normal. Gate current control that keeps the thyristor in the off state by turning the thyristor on by supplying the gate current of the thyristor at least when the regenerative current is passed. Means are provided. Here, the "switching element" means a transistor or the like (for example, a MOS type FET).
Is. "Connecting the thyristor in the opposite direction to the power supply voltage" means that the cathode of the thyristor is the power supply side (the side to which the high potential side voltage of the power supply is applied) and the anode is the ground side (the low potential side voltage of the power supply). Alternatively, it means connecting to the ground potential side). Further, "when the regenerative current is passed" means, for example, an off operation when the switching element is turned on and off to drive the DC motor. The "gate current" means a current flowing from the gate of the thyristor to the cathode. Further, the gate current control means is a circuit part (boosting part) for boosting the gate voltage of the thyristor to be higher than the cathode voltage (power supply voltage supplied to the cathode) in order to flow the gate current.
And processing means (microcomputer or the like) for controlling the operation of the booster.

In this drive device, since the thyristor provided in the bypass line is maintained in the off state when the power source is reversely connected, it is ensured that a large reverse current due to the power source reverse connection flows through the switching element and the bypass line. It is blocked and protects the circuit from reverse connection of the power supply, and does not require replacement work such as a fuse. In addition, thyristors are generally much smaller than relays and have excellent withstand voltage performance.In addition, the thyristor of this device is installed in the bypass line instead of the energization line, and only regenerative current flows when the motor is driven. (That is, the electrical use conditions are remarkably relaxed). For this reason,
In particular, when there is a change in specifications such as a higher power supply voltage, a conventional element for reverse power supply reverse connection measures (for example, FIG. 3 or FIG. 4).
The size of the thyristor can be made significantly smaller than that of the diode 11 and the relay 12, etc., and the overall size and cost of the device can be reduced. The size of the thyristor is 1 even if it is a ready-made product with a withstand voltage of 200V or 400V.
It is about 0 mm × 10 mm × 4.7 mm (about the same size as a rectifying device such as a diode that has the same withstand voltage performance), which is about half the size of a relay that has the same withstand voltage performance. is there.

Next, in a preferred aspect of the present invention, a gate turn-off thyristor (GTO thyristor) is used as the thyristor, and when the switching element is turned on, a reverse gate current is passed to the thyristor to ensure the thyristor. A reverse gate current control means for turning off is provided. Here, the "reverse gate current" means a current flowing from the cathode of the thyristor to the gate. The "reverse gate current control means" can be constituted by, for example, a short circuit line that short-circuits the gate of the thyristor to the ground side, and a transistor that opens and closes the short circuit line and that operates in synchronization with the switching element.

With such a configuration, the bypass line is brought into a conducting state (a regenerative current flows state) when the switching element is off, and the bypass line is reliably brought into a non-conducting state when the switching element is on. It is possible to realize various motor drive controls (for example, PWM control) and block the so-called through current so that the thyristor can also function as a flywheel diode, further reducing the size and cost by reducing the number of parts. Becomes Note that a thyristor has the property that when a reverse voltage is applied while the gate current is turned on and is turned on, a considerable amount of current (that is, through current) flows in the reverse direction for a moment, but a normal thyristor ( For example, what is called a normal type does not turn off (that is, does not return to the off state) once the gate current is returned to zero once it is turned on (unless the main current becomes lower than the holding current). Therefore, when using a normal thyristor that does not turn off immediately,
In order to prevent the through current from temporarily flowing when the switching element is turned on, it is necessary to separately provide a flywheel diode on the bypass line separately from the thyristor. However, as in the above-described embodiment, a GTO thyristor (a thyristor that can be immediately returned to the off state by flowing a reverse gate current) is used, and the on / off state of this thyristor has the opposite relationship to the switching element. With such control, the shoot-through current can be blocked without providing a separate flywheel diode, and as a result, the thyristor can also function as a conventional flywheel diode, and the conventional flywheel diode can be eliminated.

Further, according to another preferred aspect of the present invention, when the input signal for instructing the operation or stop of the DC motor continues for a specified time or longer (may be the case where the input signal continues for a time exceeding the specified time). It has an input determination function that determines that an input signal that is valid and does not continue for a specified time or longer is invalid, and the gate current control means starts the time when the input signal becomes active (that is, starts counting the specified time). From the point of time), the boosting of the gate voltage for flowing the gate current is started, and the boosting of the gate voltage is stopped when the input signal instructing the stop of the DC motor continues for a specified time or longer. . That is, according to one aspect of the present invention, in a normal state in which the power supply voltage is normally supplied, the boosted state of the gate voltage is maintained and the gate current is always supplied (the thyristor is always turned on). Good. However, in this aspect, the gate voltage is boosted on the condition that the input signal is input, and when the input signal for instructing the stop of the motor is confirmed, the boosting of the gate voltage is stopped even in the normal state, and the motor is stopped. A gate current is made to flow (the thyristor is turned on) only when driving the. Further, the boosting of the gate voltage starts at the time when the clocking of the specified time for determining the input signal is started.

The input determination function is used when the input signal is temporarily activated due to mechanical rattling of the operation switch (for example, the input of the operation switch is input even though the user is not actually operating it). This is a malfunction prevention function to prevent the motor from being accidentally driven when the signal temporarily commands the motor operation. It is necessary to consider vibration etc. while the vehicle is running. It is indispensable for practical use in a drive device of an in-vehicle system. Therefore, according to the above aspect, the gate current can be made to flow for the minimum necessary time, and the power consumption and heat generation due to the flow can be minimized. Moreover, since the gate voltage is started to be boosted from the start of the determination time (the specified time) of the input determination function that is usually provided, it is possible that the motor operation delay with respect to the operation command may occur due to the time required for the boosting. It can be avoided or suppressed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (First embodiment) First, a first embodiment of the present invention will be described.
FIG. 1A is a diagram showing a main circuit configuration (for example, a control portion of a driver's seat window) of a drive device (drive device for a power window of a vehicle) of this example. Next, FIG.1 (b) is a figure which shows the detail of the motor control part 22 of this apparatus. In addition,
Regarding the same components as the above-mentioned components shown in FIG. 3,
The same reference numerals are used and duplicated description is omitted. This device
As shown in FIG. 1A, a peripheral control unit 21 including a microcomputer, a motor control unit 22 including relays 7 and 8, FET 9 and the like, and a boosting unit 23 are provided. See also FIG.
As shown in (b), the thyristor 24 is connected in series to the flywheel diode 10 on the bypass line LB in the motor control unit 22.

Here, the thyristor 24 is an ordinary one not a GTO thyristor, and is connected in the opposite direction to the power supply voltage. Further, the booster unit 23 includes the peripheral control unit 2
When the control signal B output from 1 becomes active, the gate voltage of the thyristor 24 is boosted to make this gate voltage higher than the power supply voltage supplied to the cathode of the thyristor 24, and when the control signal B becomes inactive, The thyristor 24 is composed of a circuit that makes the gate voltage equal to or lower than the power supply voltage supplied to the cathode. In this case, the booster 23 and the peripheral controller 21 constitute the gate current control means of the present invention. Since the booster 23 is a circuit that generates a gate voltage by using the power supply voltage of the battery 4 as an input, it naturally does not operate normally and cannot boost the gate voltage when the battery 4 is in the reverse connection state. Further, the peripheral control unit 21 outputs the control signal A to control the motor 1 in the same manner as the peripheral control unit 2 shown in FIG. 3 according to the input determination result of the operation switch 6 and controls the control signal B as follows. To control the operation of the thyristor 24. That is, the control signal B is activated from the time when the input signal (the signal instructing the operation or stop of the motor 1) of the operation switch 6 is actively changed (that is, the time when the measurement of the specified time for the input determination is started). The boosting of the gate voltage is stopped when the input signal instructing the motor to stop continues for a specified time or longer. In this case, as a characteristic of the booster 23 described above, when the battery 4 is in the reverse connection state, the boosting of the gate voltage is not executed regardless of the state of the control signal B, but as a precaution, the power supply voltage is normally set. When not supplied, the peripheral control unit 21 may not activate the control signal B even if the input signal becomes active.

Next, FIG. 2 is a flow chart showing an example of the processing procedure of the peripheral control unit 21 which realizes the above-described control operation. This process is started when it is detected that the input signal from the operation switch 6 (in this case, a signal for instructing so-called automatic operation of the window) is changed to active (step S1). Then, in step S2, if the control signal B is inactive, the control signal B is activated and the boosting of the gate voltage of the thyristor 24 is started. As a result, if the battery 4 is normally connected and the power supply voltage is normal, an appropriate gate current flows through the thyristor 24 when the gate voltage boosting started here is completed, and the thyristor 24 moves forward. It is turned on (conductive state) in the direction from the anode to the cathode. Next, in step S3, the operation of the timer that counts the specified time for input determination is started. Next, in step S4, it is determined whether or not the gate voltage is boosted to an appropriate value. If the gate voltage is boosted, the process proceeds to the next step S5, and if not boosted, this step S4 is performed.
Repeat 4. The peripheral controller 21 receives the gate voltage of the thyristor 24 via a circuit line (not shown), and the microcomputer of the peripheral controller 21 can monitor the gate voltage. Next, in step S5, it is determined whether or not the time measurement result started in step S3 is equal to or longer than a specified time for input determination (or may be longer than the specified time). Proceed to S6, and otherwise repeat this step S5. Next, in step S6, it is determined whether or not the state of the input signal determined to be active in step S1 is continued, and if it is continued, the process proceeds to the next step S7. The process ends. Then, in step S7, it is determined whether or not the input signal is a command to start the motor 1 (that is, the start of the opening / closing operation of the window), and if it is a command to start, the process proceeds to step S8. In order to drive the motor 1 in the direction according to the command, the relays 7, 8
And the control of the FET 9 is started. On the other hand, if the input signal is an instruction to stop the motor 1, the process proceeds to step S9, the control signal B is made inactive (that is, the boosting of the gate voltage is stopped), and the process further proceeds to step S10. In order to stop, the control for stopping the operation of the relays 7 and 8 and the FET 9 is executed. Note that step S8 or S
When 10 is passed, the process of one sequence is completed.

In the drive device of the first embodiment described above,
When the power supply voltage is normal, the thyristor 24 is always turned on in the forward direction when the motor 1 is driven, and the regenerative current during the OFF operation of the FET 9 properly flows through the thyristor 24 and the flywheel diode 10. Further, the current from the power supply side to the ground side via the bypass line LB is reliably blocked by the thyristor 24 and the flywheel diode 10. The above-mentioned through current that flows backward through the thyristor 24 is blocked by the flywheel diode 10. Therefore, the PWM control of the motor 1 by the on / off operation of the FET 9 is established. In this drive device, the thyristor 24 provided on the bypass line LB is maintained in the off state by the operation of the booster 23 at the time of reverse connection of the power source. Therefore, the reverse connection due to the reverse connection of the power source is performed via the parasitic diode 9a of the FET 9 and the bypass line LB. A large current flowing in the direction is blocked, the circuit is protected from reverse connection of the power supply, and a replacement work such as a fuse is unnecessary. Moreover, the thyristor 24 is significantly smaller than a relay and is excellent in withstand voltage performance, and the thyristor 24 of this device is provided not on the energizing line but on the bypass line LB so that only the regenerative current flows when the motor is driven. (That is, the electrical use conditions are remarkably relaxed). Therefore, the voltage of the battery 4 is increased (42 V
If the specifications are changed, the thyristor 24 can be made much smaller than the conventional device for reverse power supply reverse connection countermeasures (for example, the diode 11 and the relay 12 in FIGS. 3 and 4). As a result, downsizing and cost reduction of the entire device can be realized. In the case of this device, there are relays 7 and 8 for controlling the rotation direction of the motor 1, and if the operation switch 6 is operated, the peripheral control unit 21 drives these relays 7 and 8 if the power supply is in the reverse connection state. Therefore, the reverse current flowing through the parasitic diode 9a and the current-carrying line of the motor 1 is also blocked when the power source is reversely connected, and the problem that the motor 1 operates in the reverse direction to the operation when the power source is reversely connected is avoided. By the way, even if one of the relays 7 and 8 is activated at the time of reverse connection of the power source, the reverse current flows through the motor 1 (the motor 1 rotates), so it does not become a large current that damages the circuit. .

Further, in the present apparatus, the boosting of the gate voltage is started at the time when the input signal from the operation switch 6 becomes active (at the time when the timing of the specified time for judging the input signal is started) (step S2 in FIG. 2). When the input signal for instructing the stop of the motor 1 is confirmed, the boosting of the gate voltage is stopped even in the normal state (step S in FIG. 2).
9) The gate current is supplied only when the motor 1 is driven (the thyristor 24 is turned on). Therefore, the gate current can be flowed for the minimum necessary time to suppress the power consumption and heat generation due to the minimum, and it is possible to avoid or suppress the occurrence of the motor operation delay with respect to the operation command due to the time required for boosting. If a normal transistor having no parasitic diode (for example, a bipolar transistor) is used as a switching element for driving the motor, the current at the time of reverse connection of the power supply can be blocked by the operation of the switching element. However, a normal transistor has a much larger amount of heat generation (in other words, on-resistance) than an FET, so a large heat sink (radiator) is used.
Is required to prevent overheating, which is not practical. On the other hand, in the case of the drive device using the FET as in this embodiment, a fail function of monitoring the temperature of the FET and forcibly stopping the operation or limiting the current so as not to exceed the allowable temperature is provided as necessary. Thus, it is possible to easily form an extremely small device without a heat sink.

(Second Embodiment) Next, a second embodiment of the present invention will be described. As shown in FIG. 1C, this drive device has a motor control unit 22 having a GTO thyristor 24a instead of the thyristor 24 of the first embodiment (FIG. 1B).
It consists of a. The motor control unit 22a has a GT
The flywheel diode is provided with a short-circuit line LT that short-circuits the gate of the O-thyristor 24a to the ground side, and a transistor 25 that opens and closes the short-circuit line LT and that operates in synchronization with the FET 9 according to the control signal A. 10 is deleted (the GTO thyristor 24a functions as the flywheel diode 10). Here, the peripheral control unit 21, the short-circuit line LT, and the transistor 25 constitute the reverse gate current control means of the present invention. With this configuration, when the FET 9 is turned on while the motor 1 is driven, the transistor 25 is turned on and the gate of the GTO thyristor 24a is short-circuited to the ground via the short-circuit line LT. Regardless of the state of 23, a reverse gate current flows through the GTO thyristor 24a and the GTO thyristor 24a is surely turned off (a non-conducting state that blocks both forward current and reverse current), and even without the flywheel diode 10. The aforementioned shoot-through current is blocked. Further, the bypass line LB is opened in the direction from the ground side to the power supply side (forward direction of the GTO thyristor 24a) only when the regenerative current should flow (when the FET 9 is in the OFF state in the driving state of the motor 1). Therefore, at the time when the current should not flow (when the FET 9 is on in the driving state of the motor 1), the direction from the ground side to the power supply side (forward direction of the GTO thyristor 24a) is also cut off. Therefore, according to the drive device of the second form example, in addition to the same effect as the first form example, the effect that better PWM control of the motor 1 can be realized is obtained. Further, the flywheel diode 10 becomes unnecessary, and there is an effect that further reduction in size and cost can be realized by reducing the number of parts.

It should be noted that the present invention is not limited to the above-mentioned form examples, and various modifications and applications are possible. For example, the switching element of the present invention may be provided in a power supply side energization line of a motor and drive the motor so-called high side. Further, there may be a case where there is no element such as the relays 7 and 8 in the above-described embodiment (a mode in which the motor is always driven in a fixed direction). Further, the peripheral control unit 21 and the boosting unit 23 in the above-described embodiment may be configured as a so-called ASIC as shown by a dotted line in FIG. By doing so, further size reduction and cost reduction can be achieved. Needless to say, the DC motor of the present invention is not limited to the motor of the vehicle device. The present invention is also applicable to drive devices for vehicle equipment other than power windows. For example, it can be applied to a motor drive device such as an electric sunroof, an electric power steering, an electric slide door, or an electric slide seat.

[0021]

In the drive apparatus of the present invention, the thyristor provided in the bypass line is maintained in the off state when the power source is reversely connected, so that a large reverse current flows due to the power source reverse connection via the switching element and the bypass line. Is reliably prevented, the circuit is protected from reverse connection of the power supply,
No replacement work such as fuse is required. In addition, thyristors are generally much smaller than relays and have excellent withstand voltage performance.In addition, the thyristor of this device is installed in the bypass line instead of the energization line, and only regenerative current flows when the motor is driven. (That is,
The electrical usage conditions are significantly eased). For this reason, especially when there is a change in specifications such as a high power supply voltage, the above-mentioned elements are compared with the conventional power supply reverse connection countermeasure elements (for example, the diode 11 and the relay 12 in FIGS. 3 and 4). The thyristor can be made extremely small, and the overall size and cost of the device can be reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a drive device.

FIG. 2 is a flowchart illustrating an operation of a driving device.

FIG. 3 is a circuit diagram illustrating a conventional drive device.

FIG. 4 is a circuit diagram illustrating a conventional drive device.

[Explanation of symbols]

1 Motor (DC Motor) 9 FET (Switching Element) 9a Parasitic Diode 10 Flywheel Diode 24 Thyristor 24a GTO Thyristor (Gate Turn-Off Thyristor) 21 Peripheral Control Section (Gate Current Control Means, Reverse Gate Current Control Means) 23 Boosting Section (Gates) Current control means) 25 transistors (reverse gate current control means) LB Bypass line LT Short circuit line (reverse gate current control means)

Claims (3)

[Claims] 1. A switching element which is connected to a power line of a DC motor and opens and closes the power line, and a power source side and a ground side of the DC motor in the power line for flowing a regenerative current during operation of the DC motor. In a drive device having a flywheel diode connected on a bypass line, a thyristor is connected on the bypass line in a direction opposite to a power supply voltage, and at least when the regenerative current is flowing during normal power supply. A driving device provided with gate current control means for flowing a gate current of the thyristor to turn on the thyristor and keeping the thyristor in an off state when the power supply is reversely connected and the gate current does not flow. . 2. A gate turn-off thyristor is used as the thyristor, and a reverse gate current control means is provided for causing a reverse gate current to flow through the thyristor when the switching element is turned on so as to surely turn off the thyristor. The drive device according to claim 1, wherein: 3. An input determination function of validating the input signal when an input signal for instructing the operation or stop of the DC motor continues for a specified time or more, and invalidating an input signal that does not continue for the specified time or more, The gate current control means starts boosting the gate voltage for flowing the gate current from the time when the input signal becomes active, and when the input signal instructing to stop the DC motor continues for a specified time or longer. The drive device according to claim 1, wherein boosting of the gate voltage is stopped.