JP2021145463A - Motor drive and control method - Google Patents

Abstract

To improve the accuracy of detecting a motor current.SOLUTION: A motor drive (100) includes a current detection circuit (10) that detects a current of a motor (M1), and a control unit (20) that switches between first switching control that performs switching control for a first switching element (Q1) or a second switching element (Q2), and second switching control that performs switching control for a third switching element (Q3) or a fourth switching element (Q4) according to the rotation direction of the motor (M1).SELECTED DRAWING: Figure 1

Description

The present invention relates to a motor drive device and a control method.

Patent Document 1 discloses a motor drive circuit including an H-bridge circuit and a current detection circuit connected to the H-bridge circuit. The H-bridge circuit is composed of a flywheel diode and a switch element, and is connected to a motor coil. The current detection circuit has a plurality of shunt resistors, and calculates the current value of the motor coil based on the voltage drop generated in the shunt resistors. When the motor coil is excited, the motor drive circuit simultaneously switches both a pair of source-side switch elements and sink-side switch elements arranged diagonally of the H-bridge circuit.

Japanese Patent No. 3917305

In the motor drive circuit disclosed in Patent Document 1, both the pair of source-side switch elements and the sink-side switch elements arranged diagonally of the H-bridge circuit are switched at the same time. Therefore, the direction of the current flowing through the shunt resistor is opposite between the power running of the motor and the regeneration of the motor. Therefore, the motor drive circuit has a problem that the current of the motor cannot be detected accurately.

One aspect of the present invention is to improve the accuracy of detecting the current of a motor.

In order to solve the above problems, the motor drive device according to one aspect of the present invention has a high potential side first and second switching elements connected in parallel with each other and a low potential side connected in parallel with each other. The third and fourth switching elements, the first end is connected between the first switching element, and the third switching element connected in series with the first switching element, and the second end is connected. A resistor connected between the second switching element and the fourth switching element connected in series with the second switching element, and a first input end connected to the first end to form a second input. A current detection circuit that detects the current of a motor connected in series with the resistor based on the potential difference between the first end and the second end while the end is connected to the second end, and the rotation of the motor. A first switching control that performs switching control on the first or second switching element on the high potential side and a second switching that performs switching control on the third or fourth switching element on the low potential side depending on the direction. A control unit for switching between control and control is provided.

According to the above configuration, the amplitude of the potential input to the current detection circuit is sufficiently small. As a result, even when an inexpensive current detection circuit is used, noise caused by the current detection circuit included in the signal output from the current detection circuit can be sufficiently reduced. Therefore, the accuracy of detecting the current of the motor can be improved.

As the first switching control, the control unit controls either of the first or second switching elements to switch between an ON state and an OFF state, and as the second switching control, the third Alternatively, control for switching between the ON state and the OFF state may be performed on any of the fourth switching elements.

According to the above configuration, it is possible to improve the accuracy of detecting the current of the motor when the switching element is controlled to switch between the ON state and the OFF state.

When the control unit controls driving of the motor in the first rotation direction and performs the second switching control on the fourth switching element, the first switching element is turned on and the second switching element is turned on. When the third switching element is turned off to control the driving of the motor in the second rotation direction and the first switching control is performed on the second switching element, the first and fourth switching elements are turned on. At the same time as turning it off, the third switching element may be turned on.

According to the above configuration, it is possible to easily control each switching element in order to improve the accuracy of detecting the current of the motor.

When the second end of the resistor is connected between the second switching element and the fourth switching element via the motor, the control unit moves the motor in the first rotation direction. When controlling the drive, the second switching control is performed on the fourth switching element, and when controlling the drive of the motor in the second rotation direction, the first switching control is performed on the second switching element. May be done.

In the above configuration, consider a case where the second end of the resistor is connected between the second switching element and the fourth switching element via a motor. Even in this case, it is possible to easily control each switching element in order to improve the accuracy of detecting the current of the motor.

The control unit controls driving of the motor in the first rotation direction, and when performing the first switching control on the first switching element, turns off the second and third switching elements, and at the same time, turns off the second and third switching elements. When the fourth switching element is turned on to control the drive of the motor in the second rotation direction and the second switching control is performed on the third switching element, the first and fourth switching elements are used. At the same time as turning it off, the second switching element may be turned on.

According to the above configuration, it is possible to easily control each switching element in order to improve the accuracy of detecting the current of the motor.

When the first end of the resistor is connected between the first switching element and the third switching element via the motor, the control unit moves the motor in the first rotation direction. When controlling the drive, the first switching control is performed on the first switching element, and when controlling the drive of the motor in the second rotation direction, the second switching control is performed on the third switching element. May be done.

In the above configuration, consider a case where the first end of the resistor is connected between the first switching element and the third switching element via a motor. Even in this case, it is possible to easily control each switching element in order to improve the accuracy of detecting the current of the motor.

In order to solve the above problems, the control method according to one aspect of the present invention includes a first and second switching elements on the high potential side connected in parallel with each other and a first and second switching elements on the low potential side connected in parallel with each other. The third and fourth switching elements, the first end is connected between the first switching element, and the third switching element connected in series with the first switching element, and the second end is the said. A resistor connected between the second switching element and the fourth switching element connected in series with the second switching element, and a first input end connected to the first end to form a second input end. Is connected to the second end, and a motor drive device including a current detection circuit that detects a current of a motor connected in series with the resistor based on a potential difference between the first end and the second end. The first switching control for controlling the first or second switching element on the high potential side and the third or third switching element on the low potential side according to the rotation direction of the motor. (4) A step of switching between a second switching control for performing switching control on the switching element and a step of switching the switching element is included.

According to one aspect of the present invention, the accuracy of detecting the current of the motor can be improved.

It is a block diagram which shows the structure of the motor drive device which concerns on Embodiment 1 of this invention. It is a circuit diagram for demonstrating the switching control by the motor drive device shown in FIG. It is a figure which shows the input waveform to the operational amplifier when switching control is performed as shown in FIG. It is a block diagram which shows the structure of the motor drive device which concerns on Embodiment 2 of this invention. It is a circuit diagram for demonstrating the switching control by the motor drive device shown in FIG.

[Embodiment 1]
<Structure of motor drive device>
FIG. 1 is a block diagram showing a configuration of a motor drive device 100 according to a first embodiment of the present invention. As shown in FIG. 1, the motor drive device 100 includes a first switching element Q1, a second switching element Q2, a third switching element Q3, a fourth switching element Q4, a motor M1, a resistor R1, and a current. It includes a detection circuit 10, a control unit 20, an operation switch 30, and a power supply VDD.

The motor drive device 100 is provided in a device that uses the drive of the motor M1 by the H-bridge circuit. In particular, the motor drive device 100 is preferably provided in a device that requires an accurate current of the motor M1. For example, the motor drive device 100 may be provided in a power window control unit for an automobile, a power tailgate control unit, a power slide door control unit, a power seat control unit, or the like.

Here, the motor drive device 100 will be described as being provided in the control unit of the power window. By driving the motor M1 so as to rotate it, the control unit 20 can drive an opening / closing mechanism which is a mechanical element interposed between the motor M1 and the power window. When the motor M1 rotates in the first rotation direction described later, the power window moves in the closing direction, and when the motor M1 rotates in the second rotation direction described later, the power window moves in the opening direction. The opening / closing mechanism is a regulator that changes the opening / closing position of the power window.

The first switching element Q1 and the second switching element Q2 on the high potential side are connected in parallel with each other, and the third switching element Q3 and the fourth switching element Q4 on the low potential side are also connected in parallel with each other. Further, the first switching element Q1 and the third switching element Q3 are connected in series with each other, and the second switching element Q2 and the fourth switching element Q4 are also connected in series with each other.

Specifically, the first end Q11 of the first switching element Q1 is connected to the power supply VDD and the first end Q21 of the second switching element Q2. The second end Q12 of the first switching element Q1 is connected to the first end Q31 of the third switching element Q3 and the first end R11 of the resistor R1.

The second end Q22 of the second switching element Q2 is connected to the first end Q41 of the fourth switching element Q4 and the second end M12 of the motor M1. The second end Q32 of the third switching element Q3 is connected to the second end Q42 of the fourth switching element Q4 and the ground GND.

The first switching element Q1 has a transistor T1 and a diode D1. The transistor T1 and the diode D1 are connected in parallel to each other between the first end Q11 and the second end Q12. The same applies to the second switching element Q2, the third switching element Q3, and the fourth switching element Q4. The transistors T1 to T4 may be MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) or bipolar transistors.

The first end M11 of the motor M1 is connected to the second end R12 of the resistor R1, and the second end M12 of the motor M1 is connected between the second end Q22 and the first end Q41. The motor M1 is directly connected to the resistor R1 and is connected in series with the resistor R1. The motor M1 is, for example, a brush motor.

The first end R11 of the resistor R1 is connected between the second end Q12 and the first end Q31. That is, the first end R11 is connected between the first switching element Q1 and the third switching element Q3. The second end R12 of the resistor R1 is connected to the first end M11 of the motor M1. That is, the second end R12 is connected between the second switching element Q2 and the fourth switching element Q4 via the motor M1.

The first switching element Q1, the second switching element Q2, the third switching element Q3, the fourth switching element Q4, the motor M1 and the resistor R1 form an H-bridge circuit. The H-bridge circuit is a circuit for controlling the motor M1. The resistor R1 is a shunt resistor.

The current detection circuit 10 includes an operational amplifier 11. However, the current detection circuit 10 may have a configuration other than the operational amplifier 11 for detecting the current of the motor M1, but the configuration other than the operational amplifier 11 in the current detection circuit 10 is omitted. The first input end 111 of the operational amplifier 11 is connected to the first end R11, and the second input end 112 of the operational amplifier 11 is connected to the second end R12.

The current detection circuit 10 detects the current of the motor M1 based on the potential difference between the first end R11 and the second end R12. Specifically, the operational amplifier 11 outputs the potential difference between the first input terminal 111 and the second input end 112 from the output terminal 113. The current detection circuit 10 outputs the potential difference output from the output terminal 113 of the operational amplifier 11 to the control unit 20 as an output signal S1. The output signal S1 is a signal including information on the current value of the motor M1.

The control unit 20 is connected to each of the transistors T1 to T4, and transmits drive signals G1 to G4 to each of these transistors in order to perform PWM (Pulse Width Modulation) control on the motor M1. As a result, the control unit 20 controls to switch between the ON state and the OFF state of each of the transistors T1 to T4. The control unit 20 controls the rotation speed of the motor M1 by performing PWM control on the motor M1. A driver IC for driving the transistor T1 is provided between the control unit 20 and the transistor T1. The same applies to the transistors T2 to T4.

Since the rotation speed of the motor M1 is controlled, the user can gently close the power window so that no sound is generated when the operation switch 30 is operated to close the power window. The operation switch 30 transmits the input signal I1 to the control unit 20 by being operated by the user. The input signal I1 is a signal including information indicating whether the rotation direction of the motor M1 is the first rotation direction or the second rotation direction. The second rotation direction is opposite to the first rotation direction.

Further, the control unit 20 estimates the rotation position of the motor M1 by referring to the ripple included in the output signal S1, and performs ripple control to control the rotation position of the motor M1. As a result, the rotational position of the motor M1 can be accurately estimated without providing the motor M1 with a sensor for detecting the rotational position of the motor M1, and the rotational position of the motor M1 can be accurately controlled. The ripple is caused by the shaking generated in the motor M1 when the motor M1 is rotating, and is different from the noise caused by the current detection circuit 10.

<Switching control by motor drive device>
FIG. 2 is a circuit diagram for explaining switching control by the motor drive device 100 shown in FIG. FIG. 3 is a diagram showing an input waveform to the operational amplifier 11 when switching control is performed as shown in FIG. In FIG. 2, the current detection circuit 10, the control unit 20, and the operation switch 30 are omitted.

The figure shown by F1 in FIG. 2 is a diagram showing a case where the motor M1 is driven to rotate in the first rotation direction, and the figure shown by F2 in FIG. 2 is a diagram showing the case where the motor M1 is driven to rotate in the first rotation direction. It is a figure which shows the case which is driven to rotate. Further, a control method for controlling the motor driving device 100 will be described below.

The control unit 20 switches between a first switching control that performs switching control on the second switching element Q2 and a second switching control that performs switching control on the fourth switching element Q4 according to the rotation direction of the motor M1. .. Specifically, it will be described below.

Consider a case where the control unit 20 performs switching control so as to rotate the motor M1 in the first rotation direction in response to the operation of the operation switch 30 by the user. In this case, as shown in the figure shown by F1 in FIG. 2, the control unit 20 performs the second switching control for performing the switching control on the fourth switching element Q4.

As the second switching control, the control unit 20 controls the fourth switching element Q4 to switch between the ON state and the OFF state. According to the above configuration, when the switching element is controlled to switch between the ON state and the OFF state, the accuracy of detecting the current of the motor M1 can be improved, and the manufacturing cost of the motor drive device 100 can be sufficiently reduced. Can be reduced to. The details of the reason why the effect of improving the accuracy of current detection and reducing the manufacturing cost can be obtained will be described later.

Specifically, the control unit 20 turns the transistor T4 into an ON state by outputting the drive signal G4 to the transistor T4 of the fourth switching element Q4. Further, the control unit 20 turns the transistor T4 into an OFF state by stopping the output of the drive signal G4 to the transistor T4.

The same applies to the case where the control unit 20 controls the other switching elements other than the fourth switching element Q4 to switch between the ON state and the OFF state. In this case, the control unit 20 outputs the drive signals G1 to G3 to each of the transistors T1 to T3, or stops the output of the drive signals G1 to G3 to each of the transistors T1 to T3.

Further, as described above, consider a case where the control unit 20 controls the driving of the motor M1 in the first rotation direction and also performs the second switching control on the fourth switching element Q4. In this case, the control unit 20 turns on the first switching element Q1 and turns off the second switching element Q2 and the third switching element Q3. According to the above configuration, it is possible to easily control each switching element in order to improve the accuracy of detecting the current of the motor M1 and to sufficiently reduce the manufacturing cost of the motor driving device 100. .. The details of the reason why the effect of improving the accuracy of current detection and reducing the manufacturing cost can be obtained will be described later.

Consider the case where the fourth switching element Q4 is turned on in the second switching control. In this case, in the figure shown by F1 in FIG. 2, as shown by the solid line, the current flows in the order of the transistor T1, the resistor R1, the motor M1, the transistor T4, and the ground GND. At this time, the current flows from the first end M11 toward the second end M12 with respect to the motor M1, so that the motor M1 rotates in the first rotation direction.

In the second switching control, consider the case where the fourth switching element Q4 is in the OFF state. In this case, in the figure shown by F1 in FIG. 2, as shown by the dotted line, the current flows in the order of the transistor T1, the resistor R1, the motor M1, and the diode D2 of the second switching element Q2. At this time as well, the motor M1 rotates in the first rotation direction.

Further, when the second switching control is performed, it is as follows. That is, the waveform indicating the ON state and the OFF state of the fourth switching element Q4, the input waveform to the first input terminal 111, the input waveform to the second input terminal 112, and the differential input waveform to the operational amplifier 11 are shown in FIG. It becomes as shown in the figure shown by F3 in 3.

Regardless of whether the fourth switching element Q4 is in the ON state or the OFF state, current flows from the power supply VDD to the transistor T1, the resistor R1, and the motor M1 in this order as shown in F1 of FIG. Therefore, the voltage at the first end R11 of the resistor R1 is the same as the voltage from the power supply VDD in both the ON state and the OFF state of the fourth switching element Q4. Further, the voltage at the second end R12 of the resistor R1 is lower than the voltage from the power supply VDD by the voltage drop at the resistor R1 in both the ON state and the OFF state of the fourth switching element Q4. ..

As a result, the input waveform to the first input terminal 111 connected to the first end R11 has no change in voltage, and the input waveform to the second input terminal 112 connected to the second end R12 is a voltage. The change in is small. Therefore, the differential input to the operational amplifier 11, that is, the potential difference between the first input terminal 111 and the second input terminal 112, changes greatly in conjunction with the cycle of the ON state and the OFF state of the fourth switching element Q4. Is sufficiently reduced.

On the other hand, consider a case where the control unit 20 performs switching control so as to rotate the motor M1 in the second rotation direction in response to the operation of the operation switch 30 by the user. In this case, as shown in the figure shown by F2 in FIG. 2, the control unit 20 performs the first switching control for performing the switching control on the second switching element Q2. As the first switching control, the control unit 20 controls the second switching element Q2 to switch between the ON state and the OFF state.

Further, as described above, consider a case where the control unit 20 controls the driving of the motor M1 in the second rotation direction and also performs the first switching control on the second switching element Q2. In this case, the control unit 20 turns off the first switching element Q1 and the fourth switching element Q4, and turns on the third switching element Q3.

Consider the case where the second switching element Q2 is turned on in the first switching control. In this case, in the figure shown by F2 in FIG. 2, as shown by the solid line, the current flows in the order of the transistor T2 of the second switching element Q2, the motor M1, the resistor R1, the transistor T3 of the third switching element Q3, and the ground GND. .. At this time, the current flows from the second end M12 toward the first end M11 with respect to the motor M1, so that the motor M1 rotates in the second rotation direction.

Consider the case where the second switching element Q2 is turned off in the first switching control. In this case, in the figure shown by F2 in FIG. 2, as shown by the dotted line, the current flows in the order of the diode D4 of the fourth switching element Q4, the motor M1, the resistor R1, the transistor T3, and the ground GND. At this time as well, the motor M1 rotates in the second rotation direction.

Further, when the first switching control is performed, it is as follows. That is, the waveform indicating the ON state and the OFF state of the second switching element Q2, the input waveform to the first input terminal 111, the input waveform to the second input terminal 112, and the differential input waveform to the operational amplifier 11 are shown in FIG. It becomes as shown in the figure shown by F4 in 3.

Regardless of whether the second switching element Q2 is in the ON state or the OFF state, as shown in F2 of FIG. 2, the current flows in the order of the motor M1, the resistor R1, the transistor T3, and the ground GND. Therefore, the voltage at the first end R11 of the resistor R1 is 0V regardless of whether the second switching element Q2 is in the ON state or the OFF state. Further, the voltage at the second end R12 of the resistor R1 becomes higher by the amount of voltage increase from 0 V at the resistor R1 regardless of whether the second switching element Q2 is in the ON state or the OFF state.

Therefore, the input waveform to the first input terminal 111 connected to the first end R11 has no change in voltage, and the input waveform to the second input terminal 112 connected to the second end R12 is the voltage. The change will be small. As a result, the differential input to the operational amplifier 11, that is, the change in the potential difference between the first input terminal 111 and the second input terminal 112 is also reduced.

According to the above configuration, the amplitude of the potential input to the current detection circuit 10 is sufficiently small. As a result, even when an inexpensive current detection circuit 10 is used, noise caused by the current detection circuit 10 included in the output signal S1 output from the current detection circuit 10 can be sufficiently reduced. Therefore, the accuracy of detecting the current of the motor M1 can be improved, and the manufacturing cost of the motor driving device 100 can be sufficiently reduced.

Further, as described above, when the control unit 20 performs the PWM control, the noise caused by the current detection circuit 10 is sufficiently reduced. As a result, the control unit 20 can accurately detect the ripple included in the output signal S1 output from the current detection circuit 10 when performing the ripple control. Therefore, when the control unit 20 performs both the PWM control and the ripple control, the above configuration exerts a particularly remarkable effect.

Further, the above configuration is particularly effective when the resistor R1 is directly connected to the motor M1 and is connected in series with the motor M1. This is because the problem that the noise caused by the current detection circuit 10 cannot be sufficiently reduced is a problem caused by the resistor R1 being directly connected to the motor M1 and connected in series with the motor M1. be.

As described above, when the control unit 20 controls the drive of the motor M1 in the first rotation direction, the control unit 20 performs the second switching control on the fourth switching element Q4 to drive the motor M1 in the second rotation direction. When controlling, the first switching control is performed on the second switching element Q2.

In the above configuration, consider a case where the second end R12 of the resistor R1 is connected between the second switching element Q2 and the fourth switching element Q4 via the motor M1. Even in this case, it is possible to easily control each switching element in order to improve the accuracy of detecting the current of the motor M1 and to sufficiently reduce the manufacturing cost of the motor driving device 100. can.

[Appendix 1]
In the column of "Appendix 1", a case where the noise caused by the current detection circuit 10 cannot be sufficiently reduced in the switching control will be described. The following contents described in the column of "Appendix 1" describe the problems recognized in order to obtain the configuration according to one aspect of the present invention.

Consider a case where the first switching element Q1 is controlled to switch between the ON state and the OFF state, the second switching element Q2 and the third switching element Q3 are OFF, and the fourth switching element Q4 is ON. ..

In this case, when the first switching element Q1 is in the ON state, current flows in the order of the transistor T1, the resistor R1, the motor M1, the transistor T4, and the ground GND. Further, when the first switching element Q1 is in the OFF state, a current flows from the ground GND in the order of the diode D3, the resistor R1, the motor M1 and the transistor T4. At this time, the motor M1 rotates in the first rotation direction.

Therefore, when the first switching element Q1 is in the ON state, the voltage at the first end R11 is the voltage from the power supply VDD, and the voltage at the second end R12 is the voltage at the resistor R1 rather than the voltage from the power supply VDD. The voltage becomes lower by the amount of the drop. When the first switching element Q1 is in the OFF state, the voltage at the first end R11 becomes 0V, and the voltage at the second end R12 becomes higher by the amount of voltage increase from 0V at the resistor R1.

As a result, the voltage at the first end R11 and the voltage at the second end R12 have a large change between the ON state and the OFF state of the first switching element Q1, so that the first input end 111 and the second input The change in the potential difference from the end 112 becomes large. Therefore, when the inexpensive current detection circuit 10 is used, the noise caused by the current detection circuit 10 included in the output signal S1 output from the current detection circuit 10 cannot be sufficiently reduced.

Further, when the third switching element Q3 is controlled to switch between the ON state and the OFF state, the second switching element Q2 is ON, and the first switching element Q1 and the fourth switching element Q4 are OFF. think of.

In this case, when the third switching element Q3 is in the ON state, current flows in the order of the transistor T2, the motor M1, the resistor R1, the transistor T3, and the ground GND. Further, when the third switching element Q3 is in the OFF state, current flows in the order of the transistor T2, the motor M1, the resistor R1, and the diode D1. At this time, the motor M1 rotates in the second rotation direction.

Therefore, when the third switching element Q3 is in the ON state, the voltage at the first end R11 becomes 0V, and the voltage at the second end R12 becomes higher by the amount of voltage increase from 0V at the resistor R1. When the third switching element Q3 is in the OFF state, the voltage at the first end R11 is the voltage from the power supply VDD, and the voltage at the second end R12 is the voltage at the resistor R1 rather than the voltage from the power supply VDD. The voltage becomes lower by the amount of the drop.

As a result, the voltage at the first end R11 and the voltage at the second end R12 have a large change between the ON state and the OFF state of the third switching element Q3, so that the first input end 111 and the second input The change in the potential difference from the end 112 becomes large. Therefore, when the inexpensive current detection circuit 10 is used, the noise caused by the current detection circuit 10 included in the output signal S1 output from the current detection circuit 10 cannot be sufficiently reduced.

The resistor R1 is provided between the power supply VDD and the first end Q11 and the first end Q21, or the resistor R1 is provided between the ground GND and the second end Q32 and the second end Q42. Consider the case. In these cases, since the resistor R1 is not directly connected to the motor M1, the accuracy of the current detection of the motor M1 by the current detection circuit 10 is lower than that when the resistor R1 is directly connected to the motor M1.

[Embodiment 2]
Other embodiments of the present invention will be described below. For convenience of explanation, the members having the same functions as the members described in the above-described embodiment are designated by the same reference numerals, and the description thereof will not be repeated.

<Structure of motor drive device>
FIG. 4 is a block diagram showing the configuration of the motor drive device 101 according to the second embodiment of the present invention. As shown in FIG. 4, the motor driving device 101 is different from the motor driving device 100 in the place where the resistor R1 is provided.

The first end M11 of the motor M1 is connected between the second end Q12 of the first switching element Q1 and the first end Q31 of the third switching element Q3, and the second end M12 of the motor M1 is a resistor R1. It is connected to the first end R13 of. The motor M1 is directly connected to the resistor R1 and is connected in series with the resistor R1.

The first end R13 of the resistor R1 is connected between the second end Q12 and the first end Q31 via the motor M1. That is, the first end R13 is connected between the first switching element Q1 and the third switching element Q3. The second end R14 of the resistor R1 is connected between the second end Q22 of the second switching element Q2 and the first end Q41 of the fourth switching element Q4.

<Switching control by motor drive device>
FIG. 5 is a circuit diagram for explaining switching control by the motor drive device 101 shown in FIG. In FIG. 5, the current detection circuit 10, the control unit 20, and the operation switch 30 are omitted. The figure shown by F5 in FIG. 5 is a diagram showing a case where the motor M1 is driven to rotate in the first rotation direction, and the figure shown by F6 in FIG. 5 is a diagram showing the case where the motor M1 is driven to rotate in the first rotation direction. It is a figure which shows the case which is driven to rotate.

In the motor drive device 101, the control unit 20 performs a first switching control that performs switching control on the first switching element Q1 and a second switching control that performs switching control on the third switching element Q3 according to the rotation direction of the motor M1. Switching between switching control. Specifically, it will be described below.

Consider a case where the control unit 20 performs switching control so as to rotate the motor M1 in the first rotation direction in response to the operation of the operation switch 30 by the user. In this case, as shown in the figure shown by F5 in FIG. 5, the control unit 20 performs the first switching control for performing the switching control on the first switching element Q1. As the first switching control, the control unit 20 controls the first switching element Q1 to switch between the ON state and the OFF state.

Further, as described above, consider a case where the control unit 20 controls the driving of the motor M1 in the first rotation direction and also performs the first switching control on the first switching element Q1. In this case, the control unit 20 turns off the second switching element Q2 and the third switching element Q3, and turns on the fourth switching element Q4.

Consider a case where the first switching element Q1 is turned on in the first switching control. In this case, in the figure shown by F5 in FIG. 5, as shown by the solid line, the current flows in the order of the transistor T1, the motor M1, the resistor R1, the transistor T4, and the ground GND. At this time, the current flows from the first end M11 toward the second end M12 with respect to the motor M1, so that the motor M1 rotates in the first rotation direction.

Consider a case where the first switching element Q1 is turned off in the first switching control. In this case, in the figure shown by F5 in FIG. 5, as shown by the dotted line, the current flows in the order of the diode D3, the motor M1, the resistor R1, the transistor T4, and the ground GND. At this time as well, the motor M1 rotates in the first rotation direction.

Regardless of whether the first switching element Q1 is in the ON state or the OFF state, as shown in F5 of FIG. 5, the current flows in the order of the motor M1, the resistor R1, the transistor T4, and the ground GND. Therefore, the voltage at the second end R14 of the resistor R1 is 0V regardless of whether the first switching element Q1 is in the ON state or the OFF state. Further, the voltage at the first end R13 of the resistor R1 becomes higher by the amount of voltage increase from 0 V at the resistor R1 regardless of whether the first switching element Q1 is in the ON state or the OFF state.

Therefore, the input waveform to the second input terminal 112 connected to the second end R14 has no change in voltage, and the input waveform to the first input terminal 111 connected to the first end R13 is the voltage. The change will be small. As a result, the differential input to the operational amplifier 11, that is, the change in the potential difference between the first input terminal 111 and the second input terminal 112 is also reduced.

On the other hand, consider a case where the control unit 20 performs switching control so as to rotate the motor M1 in the second rotation direction in response to the operation of the operation switch 30 by the user. In this case, as shown in the figure shown by F6 in FIG. 5, the control unit 20 performs the second switching control for performing the switching control on the third switching element Q3. As the second switching control, the control unit 20 controls the third switching element Q3 to switch between the ON state and the OFF state.

Further, as described above, consider a case where the control unit 20 controls the driving of the motor M1 in the second rotation direction and also performs the second switching control on the third switching element Q3. In this case, the control unit 20 turns off the first switching element Q1 and the fourth switching element Q4, and turns on the second switching element Q2.

Consider the case where the third switching element Q3 is turned on in the second switching control. In this case, in the figure shown by F6 in FIG. 5, as shown by the solid line, the current flows in the order of the transistor T2, the resistor R1, the motor M1, the transistor T3, and the ground GND. At this time, the current flows from the second end M12 toward the first end M11 with respect to the motor M1, so that the motor M1 rotates in the second rotation direction.

Consider the case where the third switching element Q3 is turned off in the second switching control. In this case, in the figure shown by F6 in FIG. 5, as shown by the dotted line, the current flows in the order of the transistor T2, the resistor R1, the motor M1, the diode D1, and the power supply VDD. At this time as well, the motor M1 rotates in the second rotation direction.

Regardless of whether the third switching element Q3 is in the ON state or the OFF state, current flows from the power supply VDD to the transistor T2, the resistor R1, and the motor M1 in this order as shown in F6 of FIG. Therefore, the voltage at the second end R14 is the voltage from the power supply VDD regardless of whether the third switching element Q3 is in the ON state or the OFF state. The voltage at the first end R13 is lower than the voltage from the power supply VDD by the voltage drop in the resistor R1 regardless of whether the third switching element Q3 is in the ON state or the OFF state.

Therefore, the voltage change of the input waveform to the first input terminal 111 connected to the first end R13 is small, and the input waveform to the second input terminal 112 connected to the second end R14 is the voltage. There will be no change. As a result, the differential input to the operational amplifier 11, that is, the change in the potential difference between the first input terminal 111 and the second input terminal 112 is also reduced.

Further, as described above, when the control unit 20 controls the drive of the motor M1 in the first rotation direction, the control unit 20 performs the first switching control on the first switching element Q1 in the second rotation direction of the motor M1. When controlling the drive, the second switching control is performed on the third switching element Q3.

[Appendix 2]
According to the configurations of the first and second embodiments, the control unit 20 switches between the first switching control and the second switching control depending on the rotation direction of the motor M1. The first switching control performs switching control on the first switching element Q1 or the second switching element Q2. The second switching control performs switching control on the third switching element Q3 or the fourth switching element Q4.

Further, as the first switching control, the control unit 20 controls either the first switching element Q1 or the second switching element Q2 to switch between the ON state and the OFF state. As the second switching control, the control unit 20 controls either the third switching element Q3 or the fourth switching element Q4 to switch between the ON state and the OFF state.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

10 Current detection circuit 20 Control unit 100, 101 Motor drive device 111 1st input end 112 2nd input end M1 motor Q1 1st switching element Q2 2nd switching element Q3 3rd switching element Q4 4th switching element R1 resistor R11, R13 First end of resistor R12, R14 Second end of resistor

Claims (7)

The first and second switching elements on the high potential side connected in parallel with each other,
The third and fourth switching elements on the low potential side connected in parallel with each other,
The first end is connected between the first switching element and the third switching element connected in series with the first switching element, and the second end is the second switching element and the first. A resistor connected between the fourth switching element connected in series with the two switching elements and
The first input end is connected to the first end, the second input end is connected to the second end, and is connected in series with the resistor based on the potential difference between the first end and the second end. A current detection circuit that detects the current of the motor and
Depending on the rotation direction of the motor, the first switching control that performs switching control on the first or second switching element on the high potential side and the switching control on the third or fourth switching element on the low potential side are performed. A motor drive device including a second switching control to be performed and a control unit for switching. The control unit
As the first switching control, a control for switching between an ON state and an OFF state is performed for either the first or second switching element, and the control is performed.
The motor drive device according to claim 1, wherein as the second switching control, control for switching between an ON state and an OFF state is performed on either of the third or fourth switching elements. The control unit
When controlling the drive of the motor in the first rotation direction and performing the second switching control on the fourth switching element, the first switching element is turned on and the second and third switching elements are turned on. Turn off,
When controlling the drive of the motor in the second rotation direction and performing the first switching control on the second switching element, the first and fourth switching elements are turned off and the third switching element is turned off. The motor drive device according to claim 1 or 2, wherein the motor drive device is turned on. When the second end of the resistor is connected between the second switching element and the fourth switching element via the motor, when the second end is connected to the fourth switching element.
When the control unit controls the drive of the motor in the first rotation direction, the control unit performs the second switching control on the fourth switching element and controls the drive of the motor in the second rotation direction. The motor drive device according to any one of claims 1 to 3, wherein the first switching control is performed on the second switching element. The control unit
When controlling the drive of the motor in the first rotation direction and performing the first switching control on the first switching element, the second and third switching elements are turned off and the fourth switching element is turned off. Turn on,
When controlling the drive of the motor in the second rotation direction and performing the second switching control on the third switching element, the first and fourth switching elements are turned off and the second switching element is turned off. The motor drive device according to claim 1 or 2, wherein the motor drive device is turned on. When the first end of the resistor is connected between the first switching element and the third switching element via the motor, when the first end is connected to the third switching element.
When the control unit controls the drive of the motor in the first rotation direction, the control unit performs the first switching control on the first switching element and controls the drive of the motor in the second rotation direction. The motor drive device according to any one of claims 1, 2 and 5, wherein the second switching control is performed on the third switching element. The first and second switching elements on the high potential side connected in parallel with each other,
The third and fourth switching elements on the low potential side connected in parallel with each other,
The first end is connected between the first switching element and the third switching element connected in series with the first switching element, and the second end is the second switching element and the first. A resistor connected between the fourth switching element connected in series with the two switching elements and
The first input end is connected to the first end, the second input end is connected to the second end, and is connected in series with the resistor based on the potential difference between the first end and the second end. It is a control method for controlling a motor drive device including a current detection circuit for detecting a current of a motor.
Depending on the rotation direction of the motor, the first switching control for performing switching control on the first or second switching element on the high potential side and the switching control for the third or fourth switching element on the low potential side are performed. A control method comprising a second switching control to be performed and a step of switching.

Images