JPH1084695A - Motor driving circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor driving circuit with good resporasibility to a current command as an elastic load is driven. SOLUTION: A motor driving circuit 100 is made up of an H-bridge circuit in a PWM control method. The motor driving circuit 100 has a capacitor 30, a first diode 10 for passing only a current from a power supply terminal 7 to a power circuit 5, a second diode 20 for passing only a current from a second semiconductor element P2 to the first semiconductor element P1 . Then, a circulated current is not turned back to the power terminal '7 and accumulated in the capacitor 30 to enhance a voltage applied to a motor (M) while the motor (M) is rotated forward.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor driving circuit, and more particularly to a driving circuit which is preferably applied to a motor for driving an elastic load such as a spring.

[0002]

2. Description of the Related Art Conventionally, as a driving circuit of a motor for performing a forward / reverse drive, a PWM (Puls) constituted by an H bridge has been used.
An e-width modulation (pulse width modulation) control is known. As shown in FIG. 9, this type of drive circuit 100 controls ON / OFF of a voltage applied to a motor M according to a current command 6 using four semiconductor elements P1 to P4. That is, when a forward rotation current command is given, the semiconductor elements P2 and P3 shown in FIG.
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
FF, P2 keeps ON, and P3 performs ON / OFF operation according to the duty. in this way,
In a semiconductor element in a conventional PWM control motor drive circuit, P1 or P2 keeps ON and P3 or P4 turns ON / OFF according to duty, thereby controlling forward or reverse current flowing through the motor M. Was.

[0003]

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

The present invention has been made in view of such problems of the prior art, and has improved initial response and excellent responsiveness to a current command even when an elastic load is driven. An object of the present invention is to provide a motor driving circuit.

[0005]

According to a first aspect of the present invention, there is provided a motor driving circuit for applying a forward or reverse voltage to a motor according to a current command.
A power circuit including two semiconductor elements, a current detection unit that detects a current flowing through the motor, and a pulse duty calculation that modulates a pulse width according to a difference between the current command and a current value detected by the current detection unit. And a logic circuit for controlling the operation and stop of the four semiconductor elements by an output signal from the pulse duty calculator.
A motor driving circuit comprising a bridge circuit, a first diode provided between a power supply terminal and the power circuit, for flowing only a current flowing from the power supply terminal to the power circuit; The first diode or the second semiconductor element, which is provided between the first semiconductor element that operates when the motor rotates forward and the second semiconductor element that operates when the motor rotates reversely among the two semiconductor elements. And a capacitor provided between the second diode and the first semiconductor element and between the second diode and the first semiconductor element, and a ground terminal. It is characterized by having.

According to a second aspect of the present invention, there is provided a motor driving circuit according to the present invention, wherein one of the four semiconductor elements of the power circuit is driven in accordance with forward or reverse rotation of the motor and an output signal of the pulse duty calculator. The control of the operation and the stop is performed on both of the two semiconductor elements forming a pair.

In the motor drive circuit according to the first and second aspects, when a forward rotation current command is applied, two semiconductor elements forming a pair out of the four semiconductor elements constituting the power circuit are turned on / off according to the duty. It turns off, and the remaining two pairs of semiconductor elements turn off. When the two semiconductor elements to be ON / OFF controlled 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.
Is provided to prevent current from returning to the power supply terminal, guide the current to the capacitor, and store the electric charge 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 stored in the capacitor. Therefore, the torque of the motor increases, and the responsiveness increases.

On the other hand, when a reverse current command is given, the remaining two semiconductor elements constituting the power circuit are turned on / off according to the duty, and the other two semiconductor elements are turned on / off.
It becomes FF. When the two semiconductor elements to be ON / OFF controlled 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 attempts to return to the power supply terminal. In the motor drive circuit of the present invention, the second diode is provided here. As a result, the current that tries to return to the power supply terminal is blocked, and the charge is guided to the capacitor and accumulated.

When the driven object has a secondary operating characteristic such as an elastic body, the rotational speed of the motor increases when a rotational force is applied from the elastic load.
The back electromotive voltage may rise above the supply voltage, and current tends to flow from the third semiconductor element to the second semiconductor element. This current tends to return from the second semiconductor element to the power supply terminal. However, in the motor drive circuit of the present invention, since the first diode is provided, the current trying to return to the power supply terminal is prevented. Lead to the capacitor,
The charge is stored here.

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

According to another aspect of the present invention, there is provided a motor driving circuit comprising a pair of semiconductor elements and a pair of diodes for applying a forward or reverse voltage to a motor in response to a current command. A power circuit, a current detection unit that detects a current flowing through the motor, a pulse duty calculation unit that modulates a pulse width according to a difference between the current command and a current value detected by the current detection unit, A motor circuit comprising an H-bridge circuit having a logic circuit for controlling the activation and deactivation of the pair of semiconductor elements by an output signal from a pulse duty calculation unit;
A first diode that is provided between a power terminal and the power circuit and that allows only a current flowing from the power terminal to the power circuit to flow between the first diode and the closest diode of the pair of diodes; A second diode provided between the first diode or the closest diode and flowing a current only from the closest diode to the closest semiconductor element; and And a capacitor provided between the diode and the nearest semiconductor element and a ground terminal.

According to a third aspect of the present invention, in the motor driving circuit according to the first or second aspect, of the four semiconductor elements constituting the power circuit,
Two semiconductor elements that operate during reverse rotation are diodes. Therefore, it is preferable to be applied to a case where the elastic force of the elastic load to be driven is remarkably large and returns to the initial position without passing the reverse rotation current. In the motor driving circuit according to the third aspect, 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 normal rotation. As a result, the torque at the time of normal rotation increases, and the responsiveness increases.

According to another aspect of the present invention, there is provided a motor drive circuit comprising: a power circuit including four semiconductor elements for applying a forward or reverse rotation voltage to a motor according to a current command; A current detection unit that detects a current flowing through the motor, a pulse duty calculation unit that modulates a pulse width according to a difference between the current command and a current value detected by the current detection unit, and a pulse duty calculation unit. And a logic circuit for controlling the activation and deactivation of the four semiconductor elements in response to the output signals of the two semiconductor elements connected to a power supply terminal among the four semiconductor elements. Between the power supply terminal and the power supply terminal, a current flows from the power supply terminal to the respective semiconductor elements, but does not flow in the opposite directions. And a first capacitor and a second capacitor respectively provided between a connection point between the first diode and the second diode and the two semiconductor elements and a ground terminal. It is characterized by having.

According to a fifth aspect of the present invention, there is provided a motor drive circuit according to the present invention, wherein a pair of the four semiconductor elements of the power circuit is controlled in accordance with the forward or reverse rotation of the motor and the output signal of the pulse duty calculator. The control of the operation and the stop is performed for both of the two semiconductor elements.

In the motor drive circuit according to the present invention, when a forward rotation current command is given, two semiconductor elements forming a pair out of the four semiconductor elements forming the power circuit are turned on / off according to the duty. It turns off, and the remaining two pairs of semiconductor elements turn off. This ON / OFF
When the two semiconductor elements to be controlled 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.
Is provided to prevent the current from returning to the power supply terminal, and further to guide the circulating current to the second capacitor, where the electric charge is stored. 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 stored in the second capacitor. Therefore, the torque of the motor increases, and the responsiveness increases.

On the other hand, when the reverse current command is given, the remaining two semiconductor elements constituting the power circuit are turned on / off according to the duty, and the other two semiconductor elements are turned on / off.
It becomes FF. When the two semiconductor elements to be ON / OFF controlled are in the OFF state, a circulating current flows through the motor due to the inductance of the motor armature. The circulating current flows from the fourth semiconductor element to the first semiconductor element through the motor and returns to the power supply terminal. In the motor driving 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 this circulating current is guided to the first capacitor to accumulate electric charges. As a result, the next two semiconductor elements are turned on.
The voltage applied to the motor at the time of
Increases by the voltage stored in the capacitor. Therefore, the torque of the motor increases, and the responsiveness increases. As described above, the initial response is improved in both the forward rotation and the reverse rotation.

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

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

[0019]

According to the motor driving circuit according to the first and second aspects of the present invention, the circulating current generated when the duty is OFF and the counter electromotive voltage current caused by the elastic load during the reverse rotation are stored in the capacitor. Can be applied to the motor by the voltage accumulated in the motor. As a result, the motor torque increases and the responsiveness increases.

According to the motor driving circuit of the third aspect, the motor is used as a complete generator at the time of reverse rotation, so that at the next forward rotation, a voltage higher by the voltage stored in the capacitor is applied to the motor. And as a result,
The torque at the time of forward rotation increases, and the responsiveness increases.

According to the motor drive circuit of the fourth and fifth aspects, the circulating current generated when the duty is OFF during the forward rotation and the reverse rotation is stored in the first and second capacitors, respectively. In either case, when the duty is ON, a voltage higher by the voltage stored in the capacitor can be applied to the motor. As a result, the motor torque increases and the initial response increases,
Response of the brake actuator at the beginning of braking,
The initial response of the steering actuator is further improved.

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

[0023]

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 motor drive circuit according to a first embodiment of the present invention. FIG. 1 is a diagram showing a normal rotation of the 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 calculator 1, a logic circuit 2, a signal processor 3, a current detector 4, and a power circuit 5, and further includes a power supply terminal 7 and a ground terminal 8. The voltage is applied here. A terminal 6 for inputting a current command sent from an external device is also formed.

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

Further, in the pulse duty calculating section 1,
The output obtained by this calculation is compared with a reference triangular wave created inside the circuit. If the output is larger 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
The N time becomes longer, and eventually the current command and the detected current match.

The logic circuit 2 is mainly constituted by a CPU of a microcomputer, and in accordance with a command signal from the pulse duty calculator 1, any two of the four semiconductor elements P1 to P4 constituting the power circuit 5 are connected. O
It is determined whether to perform N / OFF, and a drive signal is transmitted to the corresponding semiconductor elements P1 to P4 of the power circuit 5 for a given time.

The current detector 4 is constituted by, for example, a small resistor or a Hall element, and detects an actual current value flowing through the motor M and sends it to the signal processor 3. On the other hand, the signal processing unit 3 converts the signal from the current detection unit 4 and sends it to the pulse duty calculation unit 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 between the voltages across 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 transmit to the duty calculation unit 1.

The power circuit 5 has four semiconductor elements P1 to P1.
As shown in the figure, one semiconductor element is composed of a transistor and a diode connected in parallel. Further, the bases of the transistors of the 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 according to the duty. Or P
By turning ON / OFF 2 and P3, current in both forward and reverse directions flows through the motor M.

In the motor drive circuit 100 of the present embodiment,
First diode 1 between power supply terminal 7 and power circuit 5
0, and this first diode 10 has
It is mounted so that only a current flowing from the power supply terminal 7 to the power circuit 5 flows. That is, due to the first diode 10, the circulating current flowing when the normal rotation is stopped is:
It does not flow from the semiconductor element P2 to the power supply terminal 7 side, but flows to the capacitor 30 described later.

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

Further, a capacitor 30 is provided between the second diode 20 and the semiconductor element P 1 and the ground terminal 8.
Is provided, and controls the function of accumulating the current flowing therethrough.

In this embodiment, the first diode 1
Although the 0 and the second diode 20 are provided at the positions shown in FIG. 1, the first diode 10 has a function of flowing only a current flowing from the power supply 7 to the power circuit 5. It suffices to have a function of flowing only a current flowing from the semiconductor element P2 or the power supply 7 to the semiconductor element P1. For example, as shown in FIG. 4, the first diode 10 is configured by two diodes 11 and 12, A second diode 20 can be provided in parallel with this.

Next, the operation will be described. Hereinafter, it is assumed that the current command shown in FIG. 3 is given, and FIG.
This will be described with reference to FIG. A compression spring is used as an object to be driven by the motor M. The compression spring is contracted when the motor rotates forward, and the spring is returned to the original position when the motor rotates reversely.

(1) Operation at the time of forward rotation current command When a 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 arrows in FIG. 1 indicate the circulating current flowing when the current according to the forward rotation command is turned off.

First, at time t 1, for example, 18 A
, The pulse duty calculator 1 multiplies the difference between the current value input from the current detector 4 and the signal processor 3 and the forward 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.
And sends this signal to the logic circuit 2. In response to this signal, the logic circuit 2 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 normal rotation current shown in FIG. It sends out to each semiconductor element P1-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 is changed from the first diode 10 to the second diode 20.
The current flows through the path of the transistor of the semiconductor element P1, the current detection unit 4, the motor M, the transistor of the semiconductor element P4, and the 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 time 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 is hardly applied to the motor M, and the motor M rotates rapidly. If the motor rotates at a high speed, the back electromotive voltage approaches the supply voltage, so that the current does not flow according to the current command 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 FIG. Circuit 2 has 100
% Duty is continuously output, and the semiconductor elements P1 and P1
The four transistors continue to be ON.

Thereafter, when the spring is contracted, the rotational speed of the motor M is reduced by the reaction force, so that the back electromotive voltage is reduced, so that the current according to the current command flows. That is, since the current value detected by the current detection unit 4 and the current command approach each other, the duty output from the pulse duty calculation unit 1 decreases from 100%, and as shown from time t2 to time t3 in FIG. For example, it is 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 / OF according to the duty.
Repeat F. Thus, the value of the current flowing through the motor M becomes a value according to the current command.

Here, when the transistors of the semiconductor elements P1 and P4 are both ON, as described above, the current from the power supply terminal 7 is changed from the first diode 10 to the second diode 20 to the semiconductor element P1. The current flows through the path of transistor → current detection unit 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 to the motor M does not immediately become 0 due to the inductance of the motor armature, and the ground terminal 8 → the diode of the semiconductor element P3 → the current detection It flows from the part 4 → the motor M → the diode of the semiconductor element P2. This reflux current is
Since the flow to the power supply terminal 7 is blocked by the first diode 10, the current is accumulated in the capacitor 30 through the second diode 20.

The electric charge stored in the 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, the current from the power supply terminal 7 is changed to the first diode 10
→ the second diode 20 → the transistor of the semiconductor element P1 → the current detecting section 4 → the motor M → the transistor of the semiconductor element P4 → flows through the path of the ground terminal 8, but the voltage applied to the motor M is It is the sum of the voltages. Therefore, a voltage higher than the power supply voltage can be applied, and the torque of the motor M increases, thereby improving the responsiveness.

(2) Operation at the time of a 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 a solid line arrow in FIG. Further, the dotted arrows in FIG. 2 indicate the circulating current flowing when the current according to the reverse rotation command is turned off.

Following the forward rotation command described above, at time t3, when a forward rotation current command of, for example, -18 A is given from the current command input terminal 6 to the pulse duty calculation unit 1, the pulse duty calculation unit 1 , Current detector 4
The control gain is multiplied by the difference between the current value input from the signal processing unit 3 and the reverse current command. 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.

In response to this signal, the logic circuit 2 turns on the transistors of the semiconductor elements P2 and P3 so that the current flows in the direction of the reverse current shown in FIG.
A signal for turning off the transistors of the semiconductor elements P1 and P4 is sent to the respective semiconductor elements P1 to P4. Thereby, in the power circuit 5, the semiconductor elements P2 and P2
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 changed to 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.

When the duty command of -100% is given in this way, the current flowing through the motor M increases as shown from time t3 to time t4 in FIG. However, when the motor rotates in the reverse direction, the elastic force from the spring is applied in the rotation direction, so that the motor M rotates quickly. When the motor rotates in this manner, the back electromotive voltage may exceed the supply voltage, as shown at times t4 and A in FIG.
In this case, 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
0 and is stored in the capacitor 30. The voltage at this time naturally exceeds the supply voltage because the back electromotive force is equal to or higher than the supply voltage.

Thereafter, when the spring expands, 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 time t5 in FIG. Become. At time t3 → t5, 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 FIG. The duty of 100% continues to be output, and the transistors of the semiconductor elements P2 and P3 both become O
N will continue.

If a stopper is provided at the initial position of the motor M, the motor M stops at the time t5, and the current flows as indicated by the current command as shown from time t5 to t6 in FIG. Becomes That is, the current detection unit 4
Is closer to the current command, 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. Thus, the value of the current flowing through the motor M becomes a value according to the current command.

Here, when the transistors of the semiconductor elements P2 and P3 are both ON, as described above, the current from the power supply terminal 7 is the first diode 10 → the transistor of the semiconductor element P2 → the motor M → the current The current flows through the path from 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 zero due to the inductance of the motor armature.
And the ground terminal 8 → the diode of the semiconductor element P4 →
The current flows from the motor M to the current detection unit 4 to the diode of the semiconductor element P1. This circulating current is prevented from flowing to the power supply terminal 7 by the second diode 20, and thus is stored in the capacitor 30 as it is.

The electric charge stored in the capacitor 30 is
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, the current from the power supply terminal 7 is again changed from the first diode 10 → the transistor of the semiconductor element P2 → the motor M → the current detecting section 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 sum of the power supply voltage and the voltage of the capacitor 30. Therefore, a voltage higher than the power supply voltage can be applied, and the torque of the motor M increases, thereby improving the responsiveness.

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

As described above, in the motor drive circuit 100 of the present embodiment, when the semiconductor elements P1 to P4 are turned on / off in accordance with the duty, the circulating current at the time of OFF can be stored in the capacitor 30. Since the current generated by the back electromotive voltage of the motor at the time of reverse rotation can also be stored in the capacitor, the voltage applied at the time of forward rotation can be equal to or higher than the supply voltage. As a result, the initial drive response during forward rotation is enhanced.

Second Embodiment FIG. 5 is a circuit diagram showing a motor drive circuit according to a second embodiment of the present invention, in which members common to those in the first embodiment are given the same reference numerals. The motor drive circuit 100 of the present embodiment differs from the first embodiment in that a booster circuit 32 using a charge pump is added to the capacitor 30.
Other configurations are the same.

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

Third Embodiment FIG. 6 is a circuit diagram showing a third embodiment of the motor drive circuit according to the present invention, in which members common to those in the first embodiment are denoted 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 from the first embodiment 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 of the first embodiment.

The motor drive circuit 100 according to the present embodiment is applied, for example, when the elasticity of a spring to be driven is remarkably strong and the motor M returns to the initial position even if the current flowing through the motor M is reduced to zero. Is preferred.

In the present embodiment configured as described above, as shown in FIG. 7, at time t3, the current command is set to 0 A when the motor is rotated from the normal rotation to the reverse rotation. As a result, the duty value calculated by the pulse duty calculator 1 becomes a negative value because the detected current value flowing up to that time is positive, but in the present embodiment, the semiconductor elements P2 and P3 are connected to the diodes D2 and D3. Duty is 0% because it has been changed
And 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.
Thus, 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 reverse due to the elastic force of the spring, the current flows again from the diode D3 toward the diode D4 due to this power generation action, 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 stored in the capacitor 30 in this manner exceeds the supply voltage, the voltage applied to the motor M when the semiconductor element P1 is next turned on is changed to the voltage stored in the capacitor 30. Can be increased by minutes.

As described above, the motor drive circuit 100 of this embodiment connects the semiconductor elements P2 and P3 of the H bridge circuit to the diodes D when driving a strong elastic load.
By setting 3 and D4, the motor M can be used as a complete generator at the time of reverse rotation, and the voltage generated at the time of normal rotation can be further increased by accumulating the generated electricity in the capacitor. The responsiveness is more excellent.

Fourth Embodiment FIG. 8 is a circuit diagram showing a motor drive circuit according to a fourth embodiment of the present invention, in which members common to those in the first embodiment are given 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 connected to a current flowing from the power supply terminal 7 to the semiconductor element P1. Only the flow is mounted. That is, the circulating current flowing when the normal rotation is stopped by the first diode 10 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, a second diode 20 is provided between the power supply terminal 7 and the semiconductor element P2, and the second diode 20 allows only a current flowing from the power supply terminal 7 to the semiconductor element P2 to flow. Installed. That is, the circulating current that flows when the reverse rotation is stopped by the second diode 10 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 a 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 therethrough. Govern Further, 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 functions to accumulate the current flowing there.

In the motor drive circuit 100 of this embodiment thus configured, when a current is applied at a certain duty ratio during normal rotation, both the semiconductor elements P1 and P4 are turned ON / OFF according to the duty, and the remaining semiconductor elements P1 and P4 are turned ON / OFF. 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 supply 7 and the capacitor 30 through the first diode 10, and the semiconductor element P1 → the current detecting section 4 → the motor M → the semiconductor A current flows with the element P4,
It reaches the ground terminal 8.

On the other hand, when the semiconductor elements P1 and P4 are both O
When FF is performed, the current of the motor M continues to flow due to the inductance of the motor M, but the semiconductor element P
Since both 1 and P4 are OFF, the circulating current flows from 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 to return to the power supply terminal 7. However, in the present embodiment, since the second diode 20 is provided,
This circulating current cannot return 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, the power supply voltage of, for example, 14 V is already accumulated, and the power supply voltage is generated by the forcibly flowing circulating current. The above voltage is obtained. This circulating current flows every time the duty is OFF, that is, 10,000 times per second if the carrier frequency of the pulse width modulation is 10 KHz, so that the voltage of the capacitor 40 gradually increases,
For example, the voltage is increased to about 20 V with respect to the supply voltage of 14 V.

Next, assuming that a reverse rotation current command is given, the semiconductor elements P2 and P3 are turned ON / OF in accordance with the duty.
F, and the remaining semiconductor elements P1 and P4 are turned off.
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, for example, 2 higher than the supply voltage 14 V as described above.
Since the voltage is 0 V, the current flowing through the motor M increases as compared with the case where the motor M is driven at 14 V, and the motor M generates a larger torque and can start rotating quickly at the beginning. Thereby, the initial response of the motor M can be improved.

Thereafter, since the voltage of the capacitor 40 decreases to the power supply voltage, the same response characteristics as in the first embodiment described above are exhibited except for the initial rise.

On the other hand, when the duty is OFF, the semiconductor device P
When both P2 and P3 are turned off, the ground terminal 8
Circulates from the diode of the semiconductor element P4, the motor M, the current detector 4, the diode of the semiconductor element P1, and returns to the power supply terminal 7, but the first diode 1
It is blocked by 0 and forcibly 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 increases to, for example, 20 V by the power supply voltage and the circulating current. Since the voltage of the capacitor 30 is a voltage applied at the time of normal rotation, the initial response performance is also improved when the next normal current is applied, similarly to the operation of the capacitor 40 described above. However, if the semiconductor element P2 is ON when the circulating current is accumulated in the capacitor 30, the current is also supplied from the capacitor 40. Therefore, in order to minimize the consumption of the voltage of the capacitor 40, P2
It is desirable to perform control to turn off the power.

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

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing a first embodiment (at the time of normal rotation) of a motor drive circuit of 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 (at the time of normal rotation) of the motor drive circuit of the present invention.

FIG. 7 is a waveform diagram showing a motor current with respect to a current command in a 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]

 DESCRIPTION OF SYMBOLS 1 ... Pulse duty calculation part 2 ... Logic circuit part 3 ... Signal processing part 4 ... Current detection part 5 ... Power circuit P1-P4 ... Semiconductor element (P1: First semiconductor element, P2 ... Second semiconductor element) 6 ... Current command terminal 7 Power supply terminal 8 Ground terminal 10 First diode 20 Second diode 30 First capacitor 40 Second capacitor 32 Step-up circuit D2 Diode D3 Diode M Motor 100 Motor drive circuit

Claims (6)

[Claims] 1. A power circuit comprising four semiconductor elements for applying a forward or reverse rotation voltage to a motor according to a current command, a current detection unit for detecting a current flowing in the motor, the current command and the current A pulse duty calculator that modulates a pulse width in accordance with a difference between the current value detected by the detector and a logic circuit that controls operation and stop of the four semiconductor elements based on an output signal from the pulse duty calculator. A first diode provided between a power supply terminal and the power circuit and flowing only a current flowing from the power supply terminal to the power circuit, a first diode provided between the power supply terminal and the power circuit; A first semiconductor element that operates during forward rotation of the motor, between a diode and a second semiconductor element that operates during reverse rotation of the motor among the four semiconductor elements; A second diode provided between the first diode and the second diode and flowing only a current flowing from the second semiconductor element to the first semiconductor element; and a second diode and the first semiconductor element. A motor drive circuit, further comprising: a capacitor provided between the ground and a ground terminal. 2. A method according to claim 1, further comprising: activating and stopping two of the four semiconductor elements of said power circuit in accordance with a forward or reverse rotation of said motor and an output signal of said pulse duty calculator. 2. The motor drive circuit according to claim 1, wherein the control is performed. 3. A power circuit including a pair of semiconductor elements and a pair of diodes for applying a forward or reverse voltage to the motor in accordance with a current command, a current detection unit for detecting a current flowing in the motor, and the current A pulse duty calculator that modulates a pulse width in accordance with a difference between a command and a current value detected by the current detector; and an operation signal and a stop control of the pair of semiconductor elements based on an output signal from the pulse duty calculator. A first diode provided between a power supply terminal and the power circuit and flowing only a current flowing from the power supply terminal to the power circuit; Between the first diode and the closest diode of the pair of diodes, and the closest semiconductor element of the pair of semiconductor elements; A second diode provided between the first diode or the closest diode and flowing only a current flowing from the closest diode to the closest semiconductor element; and a ground between the second diode and the closest semiconductor element, and ground. And a capacitor provided between the terminal and the terminal. 4. A power circuit comprising four semiconductor elements for applying a forward or reverse rotation voltage to a motor in response to a current command, a current detection unit for detecting a current flowing in the motor, the current command and the current A pulse duty calculator that modulates a pulse width in accordance with a difference between the current value detected by the detector and a logic circuit that controls operation and stop of the four semiconductor elements based on an output signal from the pulse duty calculator. A motor drive circuit comprising an H-bridge circuit comprising: a power supply terminal between two of the four semiconductor elements connected to a power supply terminal and a power supply terminal; A first diode and a second diode that allow current to flow and do not flow in opposite directions, respectively, the first diode and the second die And each connection point of the over-de said two semiconductor elements, between the ground terminal, a motor drive circuit, characterized in that a first capacitor and a second capacitor, respectively. 5. A method according to claim 1, further comprising: activating and stopping two pairs of semiconductor elements of said power circuit in accordance with a forward or reverse rotation of said motor and an output signal of said pulse duty calculator. 5. The motor drive circuit according to claim 4, wherein the control is performed. 6. The motor driving circuit according to claim 1, wherein the capacitor is provided with a booster circuit.