JPH0630572A - Motor driving circuit - Google Patents

Abstract

PURPOSE:To increases a reliability by eliminating the breakdown of elements even if a power supply is misconnected erroneously. CONSTITUTION:This is a motor driving circuit 1 which has a first FETQ1 and a second FETQ2, each operating after a delay time set by a resistor r1, diodes D1, D2 which constitute a short circuit, and a relay for connecting a power supply RL1 which never operates when the power supply is connected to a wrong pole by a constant current circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive circuit used for controlling the start or stop of a small electric motor for automobiles, and more particularly to a motor drive circuit for controlling a motor of a parking brake releasing actuator.

[0002]

2. Description of the Related Art As a motor drive circuit for controlling the start or stop of a small motor for automobile electric equipment, for example, Japanese Patent Laid-Open No. Hei 2
The one described in Japanese Patent Laid-Open No. 202394 is known.

In the motor drive circuit described in the above publication, a power source which is a vehicle battery is connected to the source of one upstream side FET and the source of the other upstream side FET, and the source of one downstream side FET and the other side. The source of the downstream side FET is grounded.

A signal from the microcomputer turns on one upstream side FET and the other downstream side FET or one downstream side FET and the other upstream side FET to form an energization path in the motor to drive the motor. It was driving.

[0005]

However, in the above-mentioned motor drive circuit, when the battery is mounted on the vehicle body, if the power source and the ground are erroneously connected, each FET and the microcomputer may be destroyed. was there.

Therefore, it has been considered that by connecting a diode between the FET and the power supply, when the power supply and the ground are reversely connected, it is possible to prevent the current from flowing through the FET and the microcomputer. Since the power is supplied to the motor through the connected diode, there is a drawback that a voltage drop is remarkable and a stable motor drive voltage cannot be obtained.

[0007]

The problem to be solved by the invention is that if a power supply is directly connected to an FET to form a circuit, the element may be destroyed when the power supply is erroneously connected. It is a point.

[0008]

[Constitution of the invention]

[0009]

According to the motor drive circuit of the present invention, the source is the emitter of the first transistor and the gate is the first transistor in order not to destroy the element even if the connection of the power source is wrong. The first of which is connected to the collector of the first transistor and the drain of which is connected to the brush terminal of the motor.
And a second F whose source is connected to the emitter of the second transistor, whose gate is connected to the collector of the second transistor, and whose drain is connected to the brush terminal of the motor.
ET, a resistor connected in series to the gate of the first FET and the gate of the second FET, and the source and drain of the first FET, and the source and drain of the second FET. An output stage having a diode connected between them, a normally open fixed contact connected to the source of the first FET, a movable connection connected to the power supply, and one end connected to the power supply, a constant current A relay having a relay coil driven by, and the other end of the relay coil and the first F
ET, a constant current circuit connected to the drive signal input terminal of the second FET is provided, and in a more preferred embodiment, a pair of output stages is provided for the motor. In an even more preferred embodiment, the constant current circuit has a collector connected to the drive signal input terminal, a base connected to the ground through a Zener diode, and an emitter connected to the base of the other transistor, and between the collector and the base. One transistor connected to the resistor and the collector to the other end of the relay coil,
It is characterized in that the emitter is composed of the other transistor connected to ground via a resistor, and in a further preferred embodiment one end is the emitter of one transistor of the constant current circuit and the base of the other transistor, and the other is It is characterized by having a capacitor whose end is connected to the ground, and realized the purpose of making it highly reliable by not destroying the element even if the connection of the power supply is wrong.

[0010]

In the motor drive circuit according to the present invention, the constant current circuit excites the relay coil of the power connection relay with a constant current, and the relay coil excites with a constant current to switch the movable contact to the normally open fixed contact. Unless it works, the first F
An energization path to the motor is not formed by the ET or the second FET being turned on. Therefore, when the power supply is connected by mistake, the relay coil is not excited by the constant current circuit, so that the energizing path to the motor is not formed and the first
The power is not supplied to the FET and the second FET from the wrong direction.

Further, the first FET and the second FET are turned on separately after a preset delay time in order to discharge the drain current after the gate input capacitance has been set by the resistor for a time. Have a function.

The diode has a function of instantaneously stopping the motor in order to form a short circuit with respect to the motor when the FET is turned off from the on state.

[0013]

1 and 2 show an embodiment of a motor drive circuit according to the present invention, showing a full-bridge motor drive circuit.

The illustrated motor drive circuit 1 mainly includes a first FET Q1, a second FET Q2, a first transistor Tr1, a second transistor Tr2, a third transistor Tr3, a resistor r1 and a first diode D1 ,. Second
The first output stage 11 is composed of the diode D2.

The third FET Q3 and the fourth FET Q
4, fourth transistor Tr4, fifth transistor T
A second output stage 12 is formed from the r5, the sixth transistor Tr6, the resistor r2, the third diode D3, and the fourth diode D4 with respect to the first output stage 11 as a pair.

Then, mainly the seventh transistor Tr
Constant current circuit 13 including 7th and 8th transistors Tr8
And a power connection relay RL1 including a movable contact RL1-1, a normally open fixed contact RL1-2, and a relay coil RL1-3.

The first and third FETs Q1 and Q3 are P-channel type, the second and fourth FETs Q2 and Q4 are N-channel type, and the first and fourth transistors Tr1 and T1.
r4 is a PNP type and includes second, third, fifth, sixth, seventh and eighth transistors Tr2, Tr3, Tr5, Tr
6, Tr7, Tr8 are NPN type.

The source of the first FET Q1 of the first output stage 11 is connected via the point V to the normally open fixed contact RL1-2 of the power supply connection relay RL1 and also to the emitter of the first transistor Tr1. And the first FET
The drain of Q1 is connected to one brush terminal 10a provided in the motor 10.

The gate of the first FET Q1 is connected to the collector of the first transistor Tr1 and is also connected to one end of the resistor r1.

Further, between the source and the drain of the first FET Q1, the first direction in the forward direction from the drain to the source is provided.
Diode D1 is connected to the first FET Q1
A bidirectional Zener diode ZD1 for FET protection is connected between the source and the gate of the.

The base of the first transistor Tr1 is connected to the collector of the third transistor Tr3 via a resistor r3, and the resistor r4 is connected between the emitter and the base of the first transistor Tr1. The connection point of the resistor r4 with the emitter of the first transistor Tr1 is grounded via the resistors r5, r6 and r7.

The connection point between the resistor r3 and the collector of the third transistor Tr3 and the resistor r5 and the resistor r6.
A fifth diode D5 is connected in the forward direction from the resistor r5 to the collector of the third transistor Tr3 at the connection point of.

The emitter of the third transistor Tr3 is grounded, the base of the third transistor Tr3 is grounded via the resistor r8, and the forward direction signal input terminal (driving signal) via the resistor r9. Input terminal 2).

The source of the second FET Q2 of the first output stage 11 is grounded, and the drain of the second FET Q2 is connected to the one brush terminal 10a of the motor 10.

The gate of the second FET Q2 is connected to the other end of the resistor r1 and to the collector of the second transistor Tr2.

A second diode D2 is connected in the forward direction from the source to the drain between the source and the drain of the second FET Q2, and the second FET Q2 is connected.
A bidirectional Zener diode ZD2 for FET protection is connected between the source and the gate of the FET 2.

The base of the second transistor Tr2 is connected to the connection point of the resistors r6 and r7.

The second output stage 12 is constructed symmetrically to the first output stage 11, and the source of the third FET Q3 of the second output stage 12 is the normally open fixed contact of the power source connection relay RL1 via the point V. The third FET Q is connected to the emitters of the fourth transistor Tr4 while being connected to RL1-2.
The drain of 3 is the other brush terminal 1 provided in the motor 10.
It is connected to 0b.

The gate of the third FET Q3 is connected to the collector of the fourth transistor Tr4 and also to one end of the resistor r2.

In addition, between the source and the drain of the third FET Q3, the third FET Q3 is arranged in the forward direction from the drain to the source.
Is connected to the diode D3 of the third FET Q3
A bidirectional Zener diode ZD3 for FET protection is connected between the source and the gate of the.

The base of the fourth transistor Tr4 is connected to the collector of the sixth transistor Tr6 via the resistor r10, and the resistor r11 is connected between the emitter and the base of the fourth transistor Tr4. The connection point between the resistor r11 and the emitter of the fourth transistor Tr4 is grounded via the resistors r12, r13, r14.

Further, the resistor r10 and the collector of the sixth transistor Tr6 are connected in the forward direction from the resistor r12 to the collector of the sixth transistor Tr6 at the connection point of the resistor r12 and the resistor r13. 6 diode D
6 is connected.

The emitter of the sixth transistor Tr6 is grounded, the base of the sixth transistor Tr6 is grounded via the resistor r15 and the resistor r1.
Reverse side signal input terminal (drive signal input terminal) via 6
Connected to 3.

The source of the fourth FET Q4 of the second output stage 12 is grounded, and the drain of the fourth FET Q4 is connected to the other brush terminal 10b of the motor 10.

The gate of the fourth FET Q4 is connected to the other end of the resistor r2 and to the collector of the fifth transistor Tr5.

A fourth diode D4 is connected between the source and the drain of the fourth FET Q4 in the forward direction from the source to the drain.
A bidirectional Zener diode ZD4 for FET protection is connected between the source and the gate of No. 4 of FIG.

The base of the fifth transistor Tr5 is connected to the connection point of the resistors r13 and r14.

The forward direction signal input terminal 2 and the reverse direction signal input terminal 3 are connected to a switch (not shown),
When this switch is switched to one side, the forward direction signal input terminal 2 becomes high level (1) and the reverse direction signal input terminal 3 becomes low level (0), and when the switch is switched to the other side, The direction side signal input terminal 3 becomes high level (1) and the forward direction side signal input terminal 2 becomes low level (0). If the switches are not switched, the input terminals 2 and 3 both become low level (0).

Since the gate input of the first FET Q1 gradually reaches the on-operation potential from the off state by the time constant set by the product of the gate parasitic capacitance and the resistor R1, the first FET Q1 is turned on. As shown in FIG. 2, it turns on after a delay time T1 from off.

The second FET Q2 also has a resistor r1 and
Similarly to the first FET Q1, the third and fourth FETs Q3 and Q4 are turned off from the delay time T2 and T by the resistor r2.
3, Turns on after T4.

On the other hand, the positive side signal input terminal 2, the reverse side signal input terminal 3, the power source 50 and the first output stage 11 of the first side.
Source of the FET Q1, the third FET of the second output stage 12
A constant current circuit 13 and a power supply connection relay RL1 are provided between the source of Q3 and the source.

Moving contact RL1 of power supply connection relay RL1
-1 is connected to the power supply 50 and is also connected to one end of the relay coil RL1-3 of the power supply connection relay RL1 via the seventh diode D7. The seventh diode D7 is connected from the power supply 50 to the relay coil. It is connected in the forward direction toward RL1-3.

Relay coil R of power supply connection relay RL1
The other end of L1-3 is connected to the collector of the seventh transistor Tr7 (the other transistor) of the constant current circuit 13, and the emitter of the seventh transistor Tr7 is grounded via the current feedback resistor r17. The base of the seventh transistor Tr7 is connected to the emitter of the eighth transistor Tr8 (one transistor).

One end of a capacitor C1 whose other end is grounded is connected between the emitter of the eighth transistor Tr8 and the base of the seventh transistor Tr7, and the collector of the eighth transistor Tr8 is a load resistor r18. Through the diodes D8 and D9 connected in parallel to the signal input terminals 2 and 3 on the forward and backward sides. The diodes D8 and D9 are connected in the forward direction from the forward direction side and reverse direction side signal input terminals 2 and 3 toward the resistor r18.

The base of the eighth transistor Tr8 is grounded via the Zener diode ZD5, and the bias resistor r19 is connected between the base and collector of the eighth transistor Tr8.

Eighth transistor Tr of constant current circuit 13
Even if the voltage level from the positive direction side signal input terminal 2 or the reverse direction side signal input terminal 3 varies due to the Zener diode ZD5, the potential of the emitter 8 is substantially constant.

The seventh transistor Tr7 of the constant current circuit 13 is turned on by the constant potential of the emitter of the eighth transistor Tr8 to excite the relay coils RL1-3 of the power connection relay RL1 with the constant current.

The capacitor C1 is connected to the seventh transistor Tr8 while the eighth transistor Tr8 is turned on.
The seventh transistor Tr8 is charged when the transistor 7 is turned on.
The seventh transistor Tr starts discharging after turning off
7 is turned on for a predetermined time and then turned off.

Even if the power source 50 is accidentally connected and the voltage of the power source 50 is applied to the Zener diode ZD5, the capacitor C1 and the resistor r17 of the constant current circuit 13, the resistor r17 is also affected by the capacitor C1.
And the diode D7, the diode D8, and the diode D9 do not form a ground circuit, and thereby the relay coil RL1-3 is held in a state in which the movable contact RL1-1 is restored without being excited. The voltage of the wrong polarity is not applied to the device.

Motor drive circuit 1 having such a structure
Is the movable contact RL of the power source connection relay RL1.
In the state shown in FIG. 1 connected to 1-1, at the position A where the switch is not switched, the positive direction side signal input terminal 2 and the positive direction side signal input terminal 3 are both at the low level (0). , Second, fifth, first, fourth, third and sixth transistors Tr2, Tr5, Tr1, Tr4, T
r3 and Tr6 are off, and the first FET Q1 and the third FET
FET Q3, second FET Q2, and fourth FET Q4 are off.

Therefore, when the switch is switched to the one side at the B position, the backward signal input terminal 3 remains low level (0) and the forward signal input terminal 2 becomes high level (1). While the third transistor Tr3 is turned on, the diode D8 → resistor r18 → resistor 1
9 → By energizing the Zener diode ZD5, the eighth transistor Tr8 of the constant current circuit 13 is turned on, the capacitor C1 is charged, the seventh transistor Tr7 is turned on, and the relay coil RL1-3 of the power connection relay RL1 is turned on. It is excited by a constant current.

When the relay coils RL1-3 are excited, the movable contact RL1-1 is switched to the normally open fixed contact RL1-2, so that the power source 50 is applied to the point V.

When the third transistor Tr3 is turned on, the first transistor Tr1 is turned on at the position C, and when the first transistor Tr1 is turned on, the second FET Q2 of the first output stage 11 is turned on by the resistor. After the delay time T2 set by r1 and the delay position T2, it is turned on at the D position.

By applying the power source 50 to the point V,
The fifth transistor Tr5 is turned on, and the fifth transistor Tr5 is turned on, so that the third F of the second output stage 12 is turned on.
ETQ3 is turned on at the D position after a delay time T2 set by the resistor r2.

The third FET Q3 of the second output stage 12, the first
By turning on the second FET Q2 of the output stage 11 at the D position, the V point → the third FET Q3 → the motor 1
Since the energization path is formed from the other brush terminal 10b of 0 to the one brush terminal 10a of the motor 10 to the second FET Q2 of the first output stage 11, the motor shaft 10c provided in the motor 10 is rotated forward. .

Then, when the switch is returned from the one side at the E position, both the forward and backward signal input terminals 2 and 3 are at the low level (L), so that the third transistor Tr3 is turned off. , The third transistor Tr
Since the first transistor Tr1 is turned off by turning off the third transistor Tr2, the second FET Q2 of the first output stage 11 is cut off at the E position and the second transistor Tr2 is turned on. The FET Q1 of 11 is turned on in the F position after a delay time T1 set by the resistor r1.

When the signal input terminal 2 on the positive direction side becomes low level (L), the eighth transistor Tr8 of the constant current circuit 13 is turned off at the E position, and the capacitor C
1 starts discharging, and keeps turning on the seventh transistor Tr7 until discharging ends.

The seventh transistor Tr7 is a capacitor C
The relay coil RL1-3 of the power supply connection relay RL1 is turned off at the G position after continuing to be turned on by 1
Is demagnetized, the power supply 50 is not applied to the V point at the H position.

Since the power supply 50 is not applied to the V point at the H position, the fifth transistor Tr5 is turned off and the fifth transistor Tr5 is turned off, so that the third FET Q3 of the second output stage 12 is cut off. To be done.

The second FET Q2 of the first output stage 11 is turned off at the E position and the third FET Q3 of the second output stage 12 is turned off at the H position, so that the power supply path to the motor 10 is cut off.

When the second FET Q2 of the first output stage 11 is turned off at the E position, the V point → the third of the second output stage 12 is reached.
FET Q3 → the other brush terminal 10b of the motor 10 →
When a short circuit that passes through one brush terminal 10a of the motor 10 → the first diode D1 → the point V is formed and the current flowing through this short circuit disappears, the back electromotive force of the motor 10 causes the third output of the second output stage 12 Of the other brush terminal 10b of the motor 10 → the third diode D3 and the third FETQ until the FETQ3 of the same turns off at the H position.
3 → V point → the first FET Q1 of the first output stage 11 → a short circuit passing through one brush terminal 10a of the motor 10 is formed, so that the motor 10 stops in an instant.

When the switch is switched to the other side at the I position, the forward direction signal input terminal 2 remains low level (L) and the backward direction signal input terminal 3 becomes high level (H). When the sixth transistor Tr6 is turned on, the diode D9 → resistor r18 → resistor r
19 → By energizing the Zener diode ZD5, the eighth transistor Tr8 of the constant current circuit 13 is turned on, the capacitor C1 is charged, the seventh transistor Tr7 is turned on, and the relay coil RL1-3 of the power connection relay RL1 is turned on.
Is excited by a constant current.

When the power supply 50 is applied to the V point by the excitation of the relay coils RL1-3, the second transistor Tr2 is turned on at the J position, and the second transistor Tr2 is turned on, whereby the first output stage is turned on. 11th FE
TQ1 is turned on at the K position after a delay time T1 set by the resistor r1.

When the sixth transistor Tr6 is turned on at the I position, the fourth transistor Tr4 is turned on to J.
Turning on at the position and turning on the fourth transistor Tr4 causes the fourth FET Q4 of the second output stage 12 to turn on at the K position after a delay time T4 set by the resistor r2.

The first FET Q1 and the second FET Q1 of the first output stage 11
When the fourth FET Q4 of the output stage 12 is turned on at the K position, V point → the first FE of the first output stage 11
TQ1 → one brush terminal 10a of the motor 10 → the other brush terminal 10b of the motor 10 → the fourth of the second output stage 12
Since the energization path is formed toward the FET Q4, the motor shaft 10c provided in the motor 10 is rotated in the reverse direction.

When the switch is returned from the other side at the L position, the sixth transistor Tr6 is turned off and the fourth transistor Tr4 is turned off.
The fourth FET Q4 of the output stage 12 is cut off at the L position.

When the switch returns in the L position, the eighth transistor Tr8 of the constant current circuit 13 is turned off, and the seventh transistor Tr7 is turned on after being turned on to the N position by discharging the capacitor C1. The relay coils RL1-3 of the relay RL1 are demagnetized, and the power supply 50 is not applied to the V point at the O position. The third FET Q3 of the second output stage 12 has a delay time T3.
After that, the second transistor Tr2 is turned on in the M position, the second transistor Tr2 is turned off in the O position, and the first transistor of the first output stage 11 is turned on.
FET Q1 is cut off at the O position.

When the fourth FET Q4 of the second output stage 12 is turned off at the L position, the power supply path to the motor 10 is cut off.

When the fourth FET Q4 of the second output stage 12 is turned off at the L position, V point → the first of the first output stage 11 is increased.
FET Q1 → one brush terminal 10a of the motor 10 →
When a short circuit passing through the other brush terminal 10b of the motor 10 → the third diode D3 → the point V is formed and the current flowing through this short circuit disappears, the first electromotive force of the motor 10 causes the first output stage 11 Of the brush terminal 10a of the motor 10 → the first diode D1 and the first FETQ until the FETQ1 of the first FET is turned off at the 0 position.
Since the short circuit that passes through 1 → V point → the third FET Q3 of the second output stage 12 → the other brush terminal 10b of the motor 10 is formed, the motor 10 stops in an instant.

[0070]

As described above, since the motor drive circuit according to the present invention has the above-mentioned configuration, the first FET and the second FET are separately provided after the delay time set by the resistor. Since it is turned on, the motor can be reliably energized, and even if the power supply is mistakenly connected, the constant current circuit does not turn on the relay for power supply connection, so there is no destruction of the elements and there is no diode or FET. Since the motor can be stopped instantly by the short circuit formed by the above, there is an excellent effect that the reliability can be improved.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of an embodiment of a motor drive circuit according to the present invention.

FIG. 2 is a time chart for explaining the operation of the motor drive circuit shown in FIG.

[Explanation of symbols]

1 Motor drive circuit 2, 3 (Drive signal input terminal) Forward direction signal input terminal,
Reverse direction signal input terminal 11, 12 (output stage) First output stage, second output stage 13 Constant current circuit 50 Power supply D1, D2 Diode Q1 First FET Q2 Second FET r1, r2 Resistor RL1 Power supply connection Relay RL1-1 movable contact RL1-2 normally open fixed contact RL1-3 relay coil Tr1 first transistor Tr2 second transistor

Claims (4)

[Claims] 1. A first FET having a source connected to the emitter of the first transistor, a gate connected to the collector of the first transistor, and a drain connected to the brush terminal of the motor.
A second FET having a source connected to the emitter of the second transistor, a gate connected to the collector of the second transistor, and a drain connected to the brush terminal of the motor; and a gate of the first FET and a second FET. Between the resistor connected in series with the gate of the first FET and the source and drain of the first FET, the second FET
An output stage having a diode connected between the source and the drain of the first FET, a fixed contact connected to the source of the first FET, a movable contact connected to the power supply, and one end of the power supply. And a relay for power supply, which is connected to the relay coil and is excited by energization with a constant current, and the other end of the relay coil and the first FET and the second FET.
A motor drive circuit comprising a constant current circuit connected between the drive signal input terminal and the drive signal input terminal. 2. The motor drive circuit according to claim 1, wherein a pair of output stages is provided for the motor. 3. A constant current circuit, wherein the collector is a drive signal input terminal, the base is grounded via a Zener diode,
The emitter was connected to the base of the other transistor and the resistor was connected between the collector and the base, and the collector was connected to the other end of the relay coil and the emitter was connected to the ground via the resistor. The motor drive circuit according to claim 1 or 2, wherein the motor drive circuit comprises the other transistor. 4. A capacitor, one end of which is connected to the emitter of one transistor and the base of the other transistor of the constant current circuit, and the other end of which is connected to the ground. The motor drive circuit according to claim 1.