JP3521649B2 - Motor drive circuit - Google Patents

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, and more particularly to a drive circuit preferably applied to a motor that drives an elastic load such as a spring.

[0002]

2. Description of the Related Art Conventionally, as a drive circuit for a motor for performing forward / reverse drive, a PWM (Puls) which is conventionally composed of an H bridge is used.
e Width Modulation (pulse width modulation) control is known. As shown in FIG. 9, the drive circuit 100 of this type controls ON / OFF of the voltage applied to the motor M according to the current command 6 by using the four semiconductor elements P1 to P4. That is, when the forward rotation current command is given, the semiconductor elements P2 and P3 shown in FIG.
It becomes FF, P1 keeps ON, and P4 performs ON / OFF operation according to the duty. On the other hand, when a reverse current command is given, the semiconductor elements P1 and P4 are turned off.
It becomes FF, P2 continues to be ON, and P3 performs ON / OFF operation according to the duty. in this way,
In the semiconductor element of the conventional PWM-controlled motor drive circuit, P1 or P2 continues to be turned on and P3 or P4 is turned on / off according to the duty, whereby the forward or reverse current flowing through the motor M is controlled. It was

[0003]

However, the drive circuit 100 for a motor of this type can supply only the same voltage in both forward and reverse rotations. Therefore, the motor M
When the object to be driven has the operation characteristic of the secondary system, there is a problem that the initial rising is poor. In particular, when the object to be driven is an elastic body such as a spring, when rotating against elastic force, if it rotates quickly, the counter electromotive force asymptotically approaches the supply voltage, so the current according to the current command cannot flow. As a result, there is a problem that the torque is reduced and the responsiveness is reduced.

The present invention has been made in view of the above problems of the prior art. The present invention improves the initial response, and has excellent responsiveness to a current command even when an elastic load is driven. It is an object to provide a drive circuit for a motor.

[0005]

In order to achieve the above object, the motor drive circuit of the present invention according to claim 1 applies a forward or reverse voltage to the motor according to a current command.
A power circuit consisting One of the semiconductor element, a current detecting section for detecting a current flowing through the motor, the semiconductor in accordance with the difference between the current value detected by the current command and the current detector
An H-bridge circuit including a pulse duty calculation unit that calculates an ON / OFF time ratio of body elements and a logic circuit that controls the operation and stop of the four semiconductor elements according to an output signal from the pulse duty calculation unit In a motor drive circuit, a first diode that is provided between a power supply terminal and the power circuit and flows only a current flowing from the power supply terminal to the power circuit, the first diode, and the four semiconductor elements. The first diode or the second semiconductor element is provided between the second semiconductor element that operates when the motor rotates in the reverse direction and the first semiconductor element that operates when the motor rotates in the normal direction. A second diode that only flows a current to the semiconductor element of
It further comprises a capacitor provided between the second diode and the first semiconductor element and between the ground terminal.

According to a second aspect of the present invention, there is provided a motor drive circuit according to any one of the four semiconductor elements of the power circuit according to the forward or reverse rotation of the motor and the output signal of the pulse duty calculator. It is characterized in that control of activation and deactivation is executed for two paired semiconductor elements.

In the motor drive circuit according to the first and second aspects, when a forward rotation current command is given, two semiconductor elements forming a pair among the four semiconductor elements forming the power circuit are turned ON / OFF according to the duty. It turns off, and the other two semiconductor elements forming the pair turn off. When the two semiconductor elements controlled to be turned ON / OFF are in the OFF state, a circulating current flows through the motor due to the inductance of the motor armature. This circulating current flows from the third semiconductor element through the motor to the second semiconductor element, and tries to return to the power supply terminal. However, in the motor drive circuit of the present invention,
Since the diode is provided, the current that tries to return to the power supply terminal is blocked, the current is guided to the capacitor, and the charge is stored there. As a result, the voltage applied to the motor when the two semiconductor elements are next turned on is increased by the voltage accumulated in the capacitor from the supply voltage. Therefore, the torque of the motor is increased and the responsiveness is improved.

On the other hand, when a reverse current command is given, the remaining two semiconductor elements forming the power circuit are turned on / off according to the duty, and the other two semiconductor elements are turned on.
It becomes FF. When the two semiconductor elements controlled to be turned ON / OFF are in the OFF state, a circulating current flows through the motor due to the inductance of the motor armature. This circulating current flows from the fourth semiconductor element through the motor to the first semiconductor element and tries to return to the power supply terminal. However, in the motor drive circuit of the present invention, the second diode is provided here. Therefore, the current that tries to return to the power supply terminal is blocked, and the electric charge is led to the capacitor to accumulate the electric charge.

When the driven object has a secondary system operating characteristic such as an elastic body, the rotational speed of the motor increases when a force in the rotational direction acts from the elastic load,
The back electromotive voltage may rise above the supply voltage, and a current tends to flow from the third semiconductor element to the second semiconductor element. Then, this current tries to return to the power supply terminal from the second semiconductor element. However, in the motor drive circuit of the present invention, since the first diode is provided, the current which tries to return to the power supply terminal is blocked. , Lead to the capacitor,
Charge is accumulated here.

As a result, the voltage applied to the motor when the forward rotation current command is given next increases from the supply voltage by the voltage accumulated in the capacitor. Therefore, the torque at the time of normal rotation of the motor is increased and the responsiveness is improved.

In order to achieve the above object, a motor drive circuit according to a third aspect of the present invention comprises a pair of semiconductor elements and a pair of diodes for applying a forward or reverse voltage to the motor according to a current command. a power circuit comprising: a current detector for detecting a current flowing through the motor, in response to said difference between the current value detected by the current command and the current detector
An H-bridge circuit including a pulse duty calculation unit that calculates an ON / OFF time ratio of a semiconductor device, and a logic circuit that controls the operation and stop of the pair of semiconductor devices according to an output signal from the pulse duty calculation unit. In a motor drive circuit, a first diode that is provided between a power supply terminal and the power circuit and flows only a current flowing from the power supply terminal to the power circuit;
Between the diode and the closest diode of the pair of diodes and between the closest semiconductor element of the pair of semiconductor elements, the first diode or the closest diode to the closest semiconductor element. It is further characterized by further including a second diode for flowing only a current flowing toward the second diode, and a capacitor provided between the second diode and the closest semiconductor element and between the ground terminal.

According to a third aspect of the present invention, in the motor drive circuit of the first or second aspect, among the four semiconductor elements constituting the power circuit,
The two semiconductor elements that operate during reverse rotation are diodes. Therefore, the elastic force of the elastic load to be driven is remarkably large, and it is preferable to be applied when returning to the initial position without applying a reverse current. In the motor drive circuit according to the third aspect of the present invention, the motor is used as a complete generator during reverse rotation, so that a voltage higher than the supply voltage by the voltage stored in the capacitor can be applied to the motor during forward rotation. As a result, the torque at the time of forward rotation is increased and the responsiveness is enhanced.

In order to achieve the above object, a motor drive circuit according to a fourth aspect of the present invention is a power circuit including four semiconductor elements for applying a forward or reverse voltage to a motor according to a current command. A current detector for detecting a current flowing through the motor, and ON / OF of the semiconductor element according to a difference between the current command and a current value detected by the current detector.
A motor drive circuit comprising an H-bridge circuit including a pulse duty calculation unit for calculating an F time ratio and a logic circuit for controlling the operation and stop of the four semiconductor elements according to an output signal from the pulse duty calculation unit. A current flows from the power supply terminal to the respective semiconductor elements between the two semiconductor elements connected to the power supply terminal among the four semiconductor elements and the power supply terminal, and does not flow in the reverse direction. A second diode and a second diode respectively, and the first diode and the second diode are provided.
The first capacitor and the second capacitor are respectively provided between the grounding terminal and the respective connection points between the diode and the two semiconductor elements.

According to a fifth aspect of the motor drive circuit of the present invention, a pair of four semiconductor elements of the power circuit is paired in accordance with the forward or reverse rotation of the motor and the output signal of the pulse duty calculation section. It is characterized in that the control of the operation and the stop is executed for both of the two semiconductor elements forming.

In the motor drive circuit according to the fourth and fifth aspects, when a forward rotation current command is given, two semiconductor elements forming a pair among the four semiconductor elements forming the power circuit are turned on / off according to the duty. It turns off, and the other two semiconductor elements forming the pair turn off. This ON / OFF
When the two semiconductor elements to be controlled are in the OFF state, the circulating current flows through the motor due to the inductance of the motor armature. This circulating current flows from the third semiconductor element through the motor to the second semiconductor element and tries to return to the power supply terminal. However, in the motor drive circuit of the present invention,
Since the diode is provided, the current that tries to return to the power supply terminal is blocked, and further this circulating current is guided to the second capacitor, and the electric charge is stored therein. As a result, the voltage applied to the motor when the two semiconductor elements are turned on next increases from the supply voltage by the voltage accumulated in the second capacitor. Therefore, the torque of the motor is increased and the responsiveness is improved.

On the other hand, when a reverse current command is given, the remaining two semiconductor elements forming the power circuit are turned on / off according to the duty, and the other two semiconductor elements are turned on.
It becomes FF. When the two semiconductor elements controlled to be turned ON / OFF are in the OFF state, a circulating current flows through the motor due to the inductance of the motor armature. This circulating current flows from the fourth semiconductor element through the motor to the first semiconductor element and tries to return to the power supply terminal. However, in the motor drive circuit of the present invention, the first diode is provided here. Therefore, the current that tries to return to the power supply terminal is blocked, and further this circulating current is guided to the first capacitor to accumulate the electric charge. This turns on the next two semiconductor devices.
The voltage applied to the motor when
It increases by the voltage stored in the capacitor. Therefore, the torque of the motor is increased and the responsiveness is improved. In this way, the initial responsiveness is improved in both cases of forward rotation and reverse rotation.

Further, in the motor drive circuit of the present invention according to claim 6, the capacitor is provided with a booster circuit.

In the motor drive circuit according to the sixth aspect of the present invention, since the booster circuit is provided in the capacitor, the voltage applied to the motor becomes higher, and as a result, the responsiveness becomes better.

[0019]

According to the motor drive circuit of the first and second aspects of the present invention, the freewheeling current generated when the duty is OFF and the current of the counter electromotive voltage due to the elastic load during reverse rotation are accumulated in the capacitor. It is possible to apply a voltage as high as the voltage accumulated in the motor to the motor. As a result, the motor torque is increased and the responsiveness is enhanced.

According to the motor drive circuit of the third aspect, the motor is used as a complete generator at the time of reverse rotation, so at the time of the next forward rotation, a voltage higher than the voltage accumulated in the capacitor is applied to the motor. And as a result,
The torque at the time of forward rotation is increased and the responsiveness is enhanced.

According to the motor drive circuit of the fourth and fifth aspects, since the circulating currents generated at the time of duty OFF at the time of forward rotation and at the time of reverse rotation are stored in the first and second capacitors, respectively, during forward rotation and reverse rotation. In any of the above cases, when the duty is ON, a voltage as high as the voltage accumulated in the capacitor can be applied to the motor. As a result, the motor torque increases and the initial responsiveness increases,
The response of the brake actuator at the beginning of braking,
The steering actuator has a better initial response.

According to the motor drive circuit of the sixth aspect, since the capacitor is provided with the booster circuit, the voltage applied to the motor becomes higher, and as a result, the response becomes more excellent. .

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIGS. 1 and 2 are circuit diagrams showing a first embodiment of a motor drive circuit according to the present invention. FIG. 1 is a diagram showing a normal rotation of a motor and FIG. 2 is a diagram showing a reverse rotation of the motor.

The motor drive circuit 100 of this embodiment has a pulse duty calculation section 1, a logic circuit 2, a signal processing section 3, a current detection section 4, and a power circuit 5, and further includes a power supply terminal 7 and a ground terminal 8. And a voltage is applied here. Further, a terminal 6 for inputting a current command sent from an external device is also formed.

The pulse duty calculation unit 1 is mainly composed of a CPU of a microcomputer, and compares a current command sent from an external device or the like with the actual detected current value detected by the current detection unit 4. , Power element 5
The ON / OFF time ratio (duty) of the semiconductor elements P1 to P4 configuring the above is calculated. This control calculation is proportional control, and is calculated by, for example, output = control gain × (current command−detected current). The control gain is 50 to 10
It is set to a large value such as 0.

Furthermore, in the pulse duty calculation unit 1,
The output obtained by this calculation is compared with a reference triangular wave created inside the circuit. When the output is larger than the reference triangular wave, the corresponding semiconductor element is turned on. When the output is less than the reference triangular wave, the corresponding semiconductor element is turned on. Is output to the logic circuit 2. Thereby, when the current command is larger than the detected current, the O of the semiconductor elements P1 to P4 is
N time becomes long, and the current command and the detected current eventually match.

The logic circuit 2 is mainly composed of a CPU of a microcomputer, and operates any two of the four semiconductor elements P1 to P4 constituting the power circuit 5 in response to a command signal from the pulse duty calculation section 1. O
It is determined whether to turn off / off, and a drive signal is sent to the corresponding semiconductor elements P1 to P4 of the power circuit 5 for a given time.

The current detector 4 is composed of, for example, a small resistance or a Hall element, detects the actual current value flowing in the motor M, and sends it to the signal processor 3. On the other hand, the signal processor 3 converts the signal from the current detector 4 and sends it to the pulse duty calculator 1. In the present embodiment, a small resistor is connected in series with the motor M to form a current detection unit 4, the difference in voltage between both ends of the small resistor is amplified by the signal processing unit 3, and the amplified current signal is pulsed as a detection signal. It is configured to be sent to the duty calculation unit 1.

The power circuit 5 includes four semiconductor elements P1 to P1.
One semiconductor element is constituted by P4, and a transistor and a diode are connected in parallel as shown in the figure. Further, the bases of the transistors of the respective semiconductor elements P1 to P4 are connected so that the drive signal from the logic circuit 2 is input, and the two semiconductor elements P1 and P4 at diagonal positions are arranged according to the duty. Or P
By turning ON / OFF 2 and P3, currents in both forward and reverse directions flow in the motor M.

In the motor drive circuit 100 of this embodiment,
The first diode 1 is provided between the power supply terminal 7 and the power circuit 5.
0 is provided, and the first diode 10 has
It is attached so that only the current flowing from the power supply terminal 7 to the power circuit 5 flows. That is, by the first diode 10, the circulating current flowing when the forward rotation is stopped is
The current does not flow from the semiconductor element P2 to the power supply terminal 7 side, but to the later-described capacitor 30 side.

A second diode 20 is provided between the first diode 10 and the semiconductor element P1, and the second diode 20 includes the first diode 10 to the semiconductor element P1. It is attached so that only the current flowing to it flows. That is, due to the second diode 20, the circulating current flowing when the reverse rotation is stopped is
The current does not flow from the semiconductor element P1 to the power supply terminal 7 side and the semiconductor element P2 side, but to the capacitor 30 side described later.

Further, a capacitor 30 is provided between the second diode 20 and the semiconductor element P1 and between the ground terminal 8.
Is provided and controls the function of accumulating the current that has flowed in here.

In this embodiment, the first diode 1
0 and the second diode 20 are provided at the positions shown in FIG. 1. In short, the first diode 10 has a function of flowing only the current flowing from the power supply 7 to the power circuit 5, and the second diode 20 is Since it suffices that the semiconductor device P2 or the power supply 7 has a function of flowing only the current flowing from the power supply 7 to the semiconductor device P1, for example, as shown in FIG. 4, the first diode 10 is composed of two diodes 11 and 12, The second diode 20 may be provided in parallel with this.

Next, the operation will be described. Hereinafter, assuming the case where the current command shown in FIG. 3 is given, FIG. 1, FIG. 1 and FIG.
Will be described with reference to. A compression spring is used as an object to be driven by the motor M, and the spring is contracted during normal rotation of the motor, and is returned to its original position during reverse rotation of the motor.

(1) Operation at the time of forward rotation current command When the forward rotation command is given to the motor M, the current flowing through the motor drive circuit 100 of this embodiment is shown by a solid arrow in FIG. The dotted arrow in FIG. 1 indicates the circulating current that flows when the current according to the normal rotation command is turned off.

First, at time t1, from the current command input terminal 6 to the pulse duty calculation unit 1, for example, 18 A
When the forward rotation current command is given, the pulse duty calculation unit 1 multiplies the difference between the current value input from the current detection unit 4 and the signal processing unit 3 and the normal rotation current command by the control gain. Since the current value is 0 A and the difference is large, the duty calculated as shown in FIG. 3 is 100%.
And sends this signal to the logic circuit 2. The logic circuit 2 receives this signal and turns on the transistors of the semiconductor elements P1 and P4 and turns off the transistors of the semiconductor elements P2 and P3 so that the current flows in the direction of the forward current shown in FIG. It is sent to each of the semiconductor elements P1 to P4. As a result, in the power circuit 5, the semiconductor elements P1 and P4 are turned on, and the semiconductor elements P2 and P3 are turned off, so that the current from the power supply terminal 7 changes from the first diode 10 to the second diode 20.
→ Transistor of semiconductor element P1 → current detection unit 4 → motor M → transistor of semiconductor element P4 → ground terminal 8

When the command of 100% duty is given in this way, the current flowing through the motor M increases as shown from time t1 to t2 in FIG. However, when the reaction force from the spring, which is the object to be driven by the motor M, is still small, the load hardly acts on the motor M, so that the motor M rotates at high speed. When rotating at high speed, the counter electromotive voltage approaches the supply voltage, so that the current according to the current command stops flowing, as shown at time t2 in FIG. Since the decrease in the current flowing through the motor M is detected by the current detection unit 4 and compared with the current command by the pulse duty calculation unit 1, as shown in B of FIG. 100 for circuit 2
% Duty is continuously output, and the semiconductor elements P1 and P1
Both transistors 4 will continue to be turned on.

Then, when the spring is contracted, the rotational speed of the motor M decreases due to the reaction force thereof, so that the counter electromotive voltage decreases, and the current flows according to the current command. That is, since the current value detected by the current detection unit 4 approaches the current command, the duty output from the pulse duty calculation unit 1 decreases from 100%, as shown at time t2 → t3 in FIG. For example, it will be about 60%. This signal is output from the logic circuit 2 to the transistors of the semiconductor elements P1 and P4, and the transistors of the semiconductor elements P1 and P4 are turned on / off according to the duty.
Repeat F. As a result, the value of the current flowing through the motor M becomes the value according to the current command.

Here, when the transistors of the semiconductor elements P1 and P4 are both ON, the current from the power supply terminal 7 changes from the first diode 10 to the second diode 20 to the semiconductor element P1 as described above. The current flows through the path of transistor → current detector 4 → motor M → transistor of semiconductor element P4 → ground terminal 8. When the transistors of the semiconductor elements P1 and P4 are both OFF, the current flowing in the motor M does not immediately become 0 due to the inductance of the motor armature, but the ground terminal 8 → the diode of the semiconductor element P3 → the current detection. The current flows from the part 4 → the motor M → the diode of the semiconductor element P2. This return current is
Since the first diode 10 blocks the flow to the power supply terminal 7, it is stored in the capacitor 30 through the second diode 20.

The charge accumulated in this capacitor 30 is
Next, it acts as a rising voltage when the semiconductor element P1 is turned on. That is, when the semiconductor elements P1 and P4 are turned on next time, the current from the power supply terminal 7 is applied to the first diode 10
→ second diode 20 → transistor of semiconductor element P1 → current detection unit 4 → motor M → transistor of semiconductor element P4 → ground terminal 8 The voltage applied to the motor M is the power supply voltage of the capacitor 30. It will be the sum of the voltages. Therefore, a voltage higher than the power supply voltage can be applied, the torque of the motor M is increased, and the responsiveness is improved.

(2) Operation at the time of reverse rotation current command When a reverse rotation command is given to the motor M, the current flowing through the motor drive circuit 100 of this embodiment is shown by the solid arrow in FIG. Further, the dotted arrow in FIG. 2 indicates the circulating current that flows when the current due to this reverse rotation command is turned off.

Following the forward rotation command described above, at time t3, when the forward duty current command of, for example, -18 A is given from the input terminal 6 for the current command to the pulse duty calculation unit 1, the pulse duty calculation unit 1 concerned. , Current detector 4
And the difference between the current value input from the signal processing unit 3 and the reverse rotation current command is multiplied by the control gain. Since the current value is 18 A and the absolute value of the difference is large, the duty calculated as shown in FIG. 3 is -100%, and this signal is sent to the logic circuit 2.

The logic circuit 2 receives this signal and turns on the transistors of the semiconductor elements P2 and P3 so that the current flows in the reverse current direction shown in FIG.
A signal for turning off the transistors of the semiconductor elements P1 and P4 is sent to each of the semiconductor elements P1 to P4. As a result, in the power circuit 5, the semiconductor elements P2 and P
3 is turned on and the semiconductor elements P1 and P4 are turned off, so that the current from the power supply terminal 7 is the first diode 10 →
The current flows through the path of the transistor of the semiconductor element P2 → the motor M → the current detection unit 4 → the transistor of the semiconductor element P3 → the ground terminal 8.

In this way, when the -100% duty command is given, the current flowing through the motor M increases as shown from time t3 to t4 in FIG. However, since the elastic force from the spring is applied in the rotation direction when the motor rotates in the reverse direction, the motor M rotates rapidly. When the motor rotates in this way, the counter electromotive voltage may exceed the supply voltage, as shown at time t4 and A in FIG.
In this case, the current tends to flow from the semiconductor element P3 to P2. However, the motor drive circuit 10 of the present embodiment
At 0, since the first diode 10 is provided,
This current does not return to the power supply terminal 7, and the second diode 2
It is accumulated in the capacitor 30 through 0. The voltage at this time is naturally higher than the supply voltage because the back electromotive force is higher than the supply voltage.

After that, when the spring extends, the elastic force applied from the spring gradually decreases, so that the rotation speed of the motor M decreases and the current becomes a negative value as shown from time t4 to t5 in FIG. Become. In addition, from time t3 to t5, the motor M
Since the current flowing in the current is detected by the current detection unit 4 and compared with the current command by the pulse duty calculation unit 1, as shown in D of FIG. The duty of 100% continues to be output, and the transistors of the semiconductor elements P2 and P3 are both turned on.
N will continue.

Here, if the stopper is provided at the initial position of the motor M, the motor M stops at the time t5, and the current flows according to the current command as shown from time t5 to t6 in FIG. Becomes That is, the current detector 4
Since the current value detected in step 1 and the current command approach each other, the duty output from the pulse duty calculator 1 is -1.
It increases from 00% and becomes, for example, about -60% as shown from time t5 to t6 in FIG. This signal is output from the logic circuit 2 to the transistors of the semiconductor elements P2 and P3, and the transistors of the semiconductor elements P2 and P3 repeat ON / OFF according to the duty. As a result, the value of the current flowing through the motor M becomes the value according to the current command.

When the transistors of the semiconductor elements P2 and P3 are both ON, the current from the power supply terminal 7 is, as described above, the first diode 10 → the transistor of the semiconductor element P2 → the motor M → the current. The current flows through the path of the detection unit 4 → the transistor of the semiconductor element P3 → the ground terminal 8. When the transistors of the semiconductor elements P2 and P3 are both OFF, the current flowing through the motor M immediately becomes 0 due to the inductance of the motor armature.
However, the ground terminal 8 → the diode of the semiconductor element P4 →
The current flows from the motor M to the current detector 4 to the diode of the semiconductor element P1. The circulating current is blocked by the second diode 20 from flowing to the power supply terminal 7, and therefore is stored in the capacitor 30 as it is.

The charges accumulated in this capacitor 30 are
Next, it acts as a rising voltage when the semiconductor element P2 is turned on. That is, when the semiconductor elements P2 and P3 are turned on next time, the current from the power supply terminal 7 is again the first diode 10 → the transistor of the semiconductor element P2 → the motor M → the current detection unit 4 → the transistor of the semiconductor element P3 → the ground. Although flowing through the path of the terminal 8, the voltage applied to the motor M is the power supply voltage plus the voltage of the capacitor 30. Therefore, a voltage higher than the power supply voltage can be applied, the torque of the motor M is increased, and the responsiveness is improved.

(3) Operation at the time of forward rotation current command after one cycle Next, when the forward rotation current command is given again at time t6 in FIG. 3, the current flows at 100% duty as in the previous time. As described above, since the capacitor 30 stores a voltage equal to or higher than the supply voltage, at time t7, even if the reaction force from the spring is still small and the motor M rotates quickly, As shown, a current larger than the initial current value flows. As a result, the torque of the motor M is increased and the responsiveness is improved.

As described above, in the motor drive circuit 100 of the present embodiment, when the semiconductor elements P1 to P4 are controlled to be ON / OFF according to the duty, the circulating current at the time of OFF can be accumulated in the capacitor 30, and further. Since the current generated by the counter electromotive voltage of the motor during reverse rotation can also be stored in the capacitor, the voltage applied during forward rotation can be higher than the supply voltage. As a result, the initial response of driving at the time of normal rotation is enhanced.

Second Embodiment FIG. 5 is a circuit diagram showing a second embodiment of the motor drive circuit of the present invention, and the same members as those in the first embodiment described above are designated by the same reference numerals. The motor drive circuit 100 of the present embodiment differs from the first embodiment in that a booster circuit 32 by a charge pump is added to the capacitor 30.
Other configurations are the same.

In the motor drive circuit 100 of the present embodiment configured as described above, the operation when the forward rotation current command and the reverse rotation current command are given is basically the same as that of the first embodiment, and the semiconductor device P1 to P4 are turned on according to the duty.
When the / OFF control is performed, the circulating current at the time of OFF can be accumulated in the capacitor 30. Further, the current generated by the back electromotive force of the motor at the time of reverse rotation can also be stored in the capacitor. In addition to this, in the present embodiment, since the booster circuit 32 is added to the capacitor 30, the voltage applied during normal rotation becomes higher than the supply voltage. as a result,
The initial response of driving at the time of forward rotation is further enhanced.

Third Embodiment FIG. 6 is a circuit diagram showing a third embodiment of the motor drive circuit of the present invention, and the same members as those in the first embodiment described above are designated by the same reference numerals. FIG. 7 is a waveform diagram showing the motor current with respect to the current command.

The motor drive circuit 100 of this embodiment is different in that the semiconductor elements P2 and P3 in the first embodiment are replaced by diodes D2 and D3, respectively.
Other configurations are the same as those in the first embodiment.

The motor drive circuit 100 of the present embodiment is applied, for example, when the elastic force of the spring, which is the object to be driven, is extremely strong and the motor M returns to the initial position even if the current value flowing in the motor M is set to zero. Is preferable.

In this embodiment thus constructed, as shown in FIG. 7, at time t3, the current command is set to 0 A when the normal rotation is reversed. As a result, since the detected current value that has been flowing up to that point is positive, the duty calculated by the pulse duty calculation unit 1 has a negative value. However, in the present embodiment, the semiconductor elements P2 and P3 are connected to the diodes D2 and D3. Because it has been changed, the duty is 0%
Therefore, the semiconductor elements P1 and P4 are turned off. However, at time t3 → t4, the current flowing through the motor M does not immediately become 0 due to the inductance of the motor armature, and as shown by the dotted arrow in FIG. 6, the ground terminal 8 → diode D3 → current detector 4 → motor M → diode D2. This circulating current is stored in the capacitor 30 through the second diode 20 without returning to the power supply terminal 6 by the first diode 10.
In this way, the value of the current flowing through the motor M gradually approaches zero.

However, at time t4, when the motor M starts to rotate in the reverse direction due to the elastic force of the spring, this power generation action causes a current to flow again from the diode D3 to the diode D4 as shown by A in FIG. Become. This current is also stored in the capacitor 30 through the second diode 20 without returning to the power supply terminal 6 by the first diode 10. Since the voltage thus accumulated in the capacitor 30 exceeds the supply voltage, the voltage applied to the motor M when the semiconductor element P1 is next turned on is the voltage accumulated in the capacitor 30. It can be increased by the amount.

As described above, in the motor drive circuit 100 of this embodiment, when driving a strong elastic load, the semiconductor elements P2 and P3 of the H bridge circuit are respectively connected to the diode D.
By setting 3 and D4, the motor M can be used as a complete generator at the time of reverse rotation, and the electricity generated here can be stored in the capacitor to further increase the voltage at the time of forward rotation. , The responsiveness will be more excellent.

Fourth Embodiment FIG. 8 is a circuit diagram showing a fourth embodiment of the motor drive circuit of the present invention, and the same members as those in the first embodiment described above are designated by the same reference numerals. In the motor drive circuit 100 of the present embodiment, the first diode 10 is provided between the power supply terminal 7 and the semiconductor element P1, and the first diode 10 is a current flowing from the power supply terminal 7 to the semiconductor element P1. Only the flow is attached. That is, due to the first diode 10, the circulating current that flows when the forward rotation is stopped does not flow from the semiconductor element P2 to the power supply terminal 7 side, but flows to the second capacitor 40 described later.

Further, the second diode 20 is provided between the power supply terminal 7 and the semiconductor element P2, and the second diode 20 allows only the current flowing from the power supply terminal 7 to the semiconductor element P2 to flow. It is installed. That is, due to the second diode 10, the circulating current flowing when the reverse rotation is stopped does not flow from the semiconductor element P1 to the power supply terminal 7 side but flows to the first capacitor 30 described later.

Further, a first capacitor 30 is provided between the connection point between the first diode 10 and the semiconductor element P1 and the ground terminal 8 and has a function of accumulating the current flowing therein. Control In addition, between the connection point between the second diode 20 and the semiconductor element P2 and the ground terminal 8,
A second capacitor 40 is provided and controls the function of accumulating the current flowing there.

In the motor drive circuit 100 of the present embodiment configured as described above, when current is applied at a certain duty ratio during normal rotation, both semiconductor elements P1 and P4 are turned on / off according to the duty, and the remaining Semiconductor element P2
And P3 are both turned off.

Here, when the semiconductor elements P1 and P4 are turned on, a voltage is supplied from the power source 7 and the capacitor 30 through the first diode 10, and the semiconductor element P1 → current detecting section 4 → motor M → semiconductor Element P4 and current flow,
It reaches the ground terminal 8.

On the other hand, the semiconductor elements P1 and P4 are both O
When FF is performed, the current of the motor M tries to continue flowing due to the inductance of the motor M, but the semiconductor element P
Since both 1 and P4 are OFF, the circulating current flows in the order of the ground terminal 8 → the diode of the semiconductor element P3 → the current detection unit 4 → the motor M → the diode of the semiconductor element P2, and tries to return to the power supply terminal 7. However, in this embodiment, since the second diode 20 is provided,
This circulating current cannot flow back to the power supply terminal 7 and flows into the capacitor 40. At this time, since the capacitor 40 is originally connected so that the current from the power supply terminal 7 can flow in, a power supply voltage of, for example, 14 V has already been accumulated, and the power supply voltage is forced to flow by the circulating current. It becomes the above voltage. This circulating current flows in every duty OFF, that is, when the carrier frequency of pulse width modulation is 10 KHz, flows in 10,000 times per second, so that the voltage of the capacitor 40 gradually rises,
For example, the voltage rises to about 20V with respect to the supply voltage of 14V.

Next, if a reverse current command is given, the semiconductor elements P2 and P3 are turned on / off according to the duty.
Then, the remaining semiconductor elements P1 and P4 are turned off.
Then, when the semiconductor elements P2 and P3 are turned on, the voltage of the capacitor 40 is applied to the motor M via the semiconductor element P2. Here, the voltage of the capacitor 40 is higher than the supply voltage 14V as described above, for example, 2V.
Since it is 0 V, the current flowing through the motor M is increased as compared with the case of driving at 14 V, the motor M generates a larger torque, and the rotation can be started quickly in the initial stage. Thereby, the initial response of the motor M can be improved.

After that, since the voltage of the capacitor 40 drops to the power supply voltage, the response characteristics similar to those of the above-described first embodiment are exhibited except for the initial rising.

On the other hand, when the duty is OFF, the semiconductor element P
When both 2 and P3 are turned off, this time the ground terminal 8
A circulating current flows from the diode of the semiconductor element P4 to the motor M to the current detection unit 4 to the diode of the semiconductor element P1 to return to the power supply terminal 7, but the first diode 1
It is blocked by 0 and forcedly flows into the capacitor 30. Since the current from the power supply is also supplied to the capacitor 30, the voltage of the capacitor 30 also rises to, for example, 20 V due to this power supply voltage and the circulating current. Since the voltage of the capacitor 30 is the voltage applied at the time of forward rotation, the initial response performance is improved also when the forward current is applied next, in the same manner as the action of the capacitor 40 described above. However, when the semiconductor element P2 is turned on when the circulating current is accumulated in the capacitor 30, the current is also supplied from the capacitor 40, so that the voltage of the capacitor 40 is not consumed as much as possible. P2
It is desirable to perform control to turn off also.

The embodiments described above are described for facilitating the understanding of the present invention and not for limiting the present invention. Therefore, each element disclosed in the above-described embodiment is intended to include all design changes and equivalents within the technical scope of the present invention.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram showing a first embodiment (during forward rotation) of a motor drive circuit according to the present invention.

FIG. 2 is an electric circuit diagram showing a first embodiment (during reverse rotation) of a motor drive circuit according to the present invention.

FIG. 3 is a waveform diagram showing a motor current and a duty with respect to a current command in the first embodiment.

FIG. 4 is an electric circuit diagram showing a modified example of the first and second diodes according to the present invention.

FIG. 5 is an electric circuit diagram showing a second embodiment of the motor drive circuit of the present invention.

FIG. 6 is an electric circuit diagram showing a third embodiment (during forward rotation) of the motor drive circuit according to the present invention.

FIG. 7 is a waveform diagram showing a motor current with respect to a current command in the third embodiment.

FIG. 8 is an electric circuit diagram showing a fourth embodiment of the motor drive circuit of the present invention.

FIG. 9 is an electric circuit diagram showing a conventional motor drive circuit.

[Explanation of symbols]

1 ... Pulse duty calculator 2 ... Logic circuit section 3 ... Signal processing unit 4 Current detector 5 ... Power circuit P1 to P4 ... Semiconductor element (P1 ... First semiconductor element, P2 ... Second semiconductor element) 6 ... Current command terminal 7 ... Power supply terminal 8 ... Grounding terminal 10 ... First diode 20 ... Second diode 30 ... first capacitor 40 ... Second capacitor 32 ... Booster circuit D2 ... Diode D3 ... Diode M ... motor 100 ... Motor drive circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02P 5/00-5/26 H02P ^7/ 00-7/34

Claims (6)

(57) [Claims] 1. A power circuit composed of four semiconductor elements for applying a forward or reverse voltage to a motor according to a current command, a current detector for detecting a current flowing through the motor, the current command and the current The ON / OFF time ratio of the semiconductor element is measured according to the difference from the current value detected by the detector.
In a drive circuit for a motor, which comprises an H-bridge circuit including a pulse duty calculation unit for calculating and a logic circuit for controlling operation and stop of the four semiconductor elements according to an output signal from the pulse duty calculation unit, a power supply terminal and A first diode provided between the power circuit and flowing only a current from the power supply terminal to the power circuit; and a second diode of the first diode and the four semiconductor elements, which operates when the motor reverses. It is provided between the semiconductor element and the first semiconductor element that operates at the time of normal rotation of the motor, and flows only the current flowing from the first diode or the second semiconductor element to the first semiconductor element. A second diode, a capacitor provided between the second diode and the first semiconductor element, and a ground terminal. A drive circuit for a motor, characterized in that 2. A normal rotation or a reverse rotation of the motor and an output signal of the pulse duty calculator, both of which actuate and stop a pair of two semiconductor elements of the four semiconductor elements of the power circuit. 2. The motor drive circuit according to claim 1, wherein the control is executed. 3. A power circuit composed of a pair of semiconductor elements and a pair of diodes for applying a forward or reverse voltage to the motor according to a current command, a current detector for detecting a current flowing through the motor, and the current. The ON / OFF time ratio of the semiconductor element is measured according to the difference between the command and the current value detected by the current detector.
In a motor drive circuit including an H-bridge circuit that includes a pulse duty calculation unit that performs calculation and a logic circuit that controls the operation and stop of the pair of semiconductor elements according to an output signal from the pulse duty calculation unit, a power supply terminal and A first diode provided between the power circuit and flowing only a current flowing from the power supply terminal to the power circuit; between the first diode and a diode closest to the pair of diodes; A second diode which is provided between the closest semiconductor element of the pair of semiconductor elements, and which allows only a current flowing from the first diode or the closest diode to the closest semiconductor element to flow, and the second diode And a capacitor provided between the semiconductor element and the ground terminal. And the drive circuit of the motor. 4. A power circuit composed of four semiconductor elements for applying a forward or reverse voltage to a motor according to a current command, a current detector for detecting a current flowing through the motor, the current command and the current. The ON / OFF time ratio of the semiconductor element is measured according to the difference from the current value detected by the detector.
A pulse duty calculation unit for calculation, in the drive circuit of the motor consists of an H-bridge circuit and a logic circuit for performing the operation and stop control of the four semiconductor elements by the output signal from the pulse duty calculation unit, the four Between the two semiconductor elements connected to the power supply terminal among the semiconductor elements and the power supply terminal, a current flows from the power supply terminal to each of the semiconductor elements and does not flow in the opposite direction. Two diodes are respectively provided, and a first capacitor and a second capacitor are provided between the grounding terminal and the respective connection points of the first diode and the second diode and the two semiconductor elements. A motor drive circuit characterized by being provided respectively. 5. A normal or reverse rotation of the motor and an output signal of the pulse duty calculator, both of which actuate and stop a pair of two semiconductor elements of the four semiconductor elements of the power circuit. 5. The motor drive circuit according to claim 4, wherein the control is executed. 6. The drive circuit for a motor according to claim 1, wherein the capacitor is provided with a booster circuit.