Motor driver

Abstract

To keep a halt state of driving of a motor M with low consumption current.SOLUTION: A motor driver 1 for driving a motor M is formed of a high-side transistor QH and a low-side transistor QL, and includes a half-bridge output stage in which the motor M is connected to a connection terminal BR at which the high-side transistor QH and the low-side transistor QL are connected, and a control circuit 10 for monitoring a terminal voltage V1 of the control terminal BR. The control circuit 10 initiates a brake mode, in which the motor M is stopped while having the high-side transistor QH turned off and the low-side transistor turned on. When the terminal voltage V1 is lower than a first set voltage Vth1 in the brake mode, the control circuit 10 connects the connection terminal BR to a potential at which a halt state of the motor M can be maintained, with the high-side transistor QH and the low-side transistor QL turned off.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a motor driver. [Background technology]

[0002] 2. Description of the Related Art As a motor driver used to drive a brushed DC motor, a motor driver having a brake mode for stopping the driving of the motor is known (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-29084

[0004] [overview] In the motor driver described in Patent Document 1, when the motor driver transitions to a brake mode in which the drive of the motor is stopped, the high-side drive circuit that drives the high-side transistor of the H-bridge circuit is shut down and the low-side transistor is turned on. Because the low-side transistor is turned on, a circuit current of the order of several mA flows through a circuit such as an internal power supply that drives the low-side transistor, resulting in current consumption.

[0005] An object of the present disclosure is to provide a motor driver that can maintain a stopped state of motor drive with low current consumption.

[0006] In order to solve the above-mentioned problems, one aspect of the present disclosure is a motor driver for driving a motor, the motor driver including a half-bridge output stage including a high-side transistor and a low-side transistor, the motor being connected to a connection terminal to which the high-side transistor and the low-side transistor are connected, and a control circuit for monitoring a terminal voltage of the connection terminal. The control circuit turns off the high-side transistor and turns on the low-side transistor to start a brake mode for stopping the motor, and in the brake mode, when the terminal voltage is lower than a first set voltage, the control circuit turns off the high-side transistor and the low-side transistor and connects the connection terminal to a potential capable of maintaining the motor stopped. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a configuration diagram of a motor driver according to an embodiment. [Diagram 2] FIG. 2 is a circuit diagram of a brake circuit provided in the control circuit of the motor driver according to the embodiment. [Diagram 3] FIG. 3 is a diagram showing the relationship between the terminal voltage V1 of the motor and the signal voltage V2 input to the inverting input terminal of the comparator provided in the brake circuit in the brake mode of the motor driver according to the embodiment. [Figure 4] FIG. 4 is a diagram showing the relationship between the terminal voltage V1 of the motor and the output voltage V3 of the comparator provided in the brake circuit in the brake mode of the motor driver according to the embodiment.

[0008] [Detailed Description] Hereinafter, a motor driver according to an embodiment will be described in detail with reference to the drawings. Note that the embodiments described below are comprehensive or specific examples. The numerical values, shapes, materials, components, installation positions and connection forms of the components shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, those components that are not described in the independent claims showing the highest concept may be arbitrarily configured. In the drawings, the dimensions are exaggerated for the sake of explanation and may differ from the actual dimensions. In addition, the following embodiments and their modified examples may include similar components, and the same reference numerals are used to denote the same components, and redundant explanations will be omitted.

[0009] The basic configuration of a motor driver 1 according to an embodiment will be described with reference to FIG.

[0010] The motor driver 1 includes an H-bridge circuit for driving a brushed DC motor M (hereinafter, referred to as motor M), and a control circuit 10 for controlling the H-bridge circuit and the motor M.

[0011] The motor M is, for example, an in-vehicle motor used to drive windows, seats, seat belts, mirrors, wipers, and the like.

[0012] The H-bridge circuit includes a first half-bridge output stage composed of a first high-side transistor QH1 and a first low-side transistor QL1, and a second half-bridge output stage composed of a second high-side transistor QH2 and a second low-side transistor QL2. The first high-side transistor QH1, the first low-side transistor QL1, the second high-side transistor QH2, and the second low-side transistor QL2 can be, for example, N-channel MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors).

[0013] A first electrode (e.g., drain) of the first high-side transistor QH1 and a first electrode (e.g., drain) of the second high-side transistor QH2 are connected to a terminal VB to which a DC power supply for driving the motor M is connected. A second electrode (e.g., source) of the first high-side transistor QH1 is connected in series to a first electrode (e.g., drain) of the first low-side transistor QL1. A second electrode (e.g., source) of the second high-side transistor QH2 is connected in series to a first electrode (e.g., drain) of the second low-side transistor QL2. A second electrode (e.g., source) of the first low-side transistor QL1 and a second electrode (e.g., source) of the second low-side transistor QL2 are connected to a ground potential (earth potential) GND. A connection point between the first high-side transistor QH1 and the first low-side transistor QL1 is connected to a + terminal of the motor M, and a connection point between the second high-side transistor QH2 and the second low-side transistor QL2 is connected to a - terminal of the motor M.

[0014] The control circuit 10 includes high-side drive circuits 11-1 and 11-2, low-side drive circuits 12-1 and 12-2, and a brake circuit 13. The high-side drive circuit 11-1 is connected to a control electrode (e.g., gate) of the first high-side transistor QH1 via a terminal GH1, and controls the on-off of the first high-side transistor QH1. The high-side drive circuit 11-2 is connected to a control electrode (e.g., gate) of the second high-side transistor QH2 via a terminal GH2, and controls the on-off of the second high-side transistor QH2. The low-side drive circuit 12-1 is connected to a control electrode (e.g., gate) of the first low-side transistor QL1 via a terminal GL1, and controls the on-off of the first low-side transistor QL1. The low-side drive circuit 12-2 is connected to a control electrode (e.g., gate) of the second low-side transistor QL2 via a terminal GL2, and controls the on-off of the second low-side transistor QL2. The brake circuit 13 is connected to the positive terminal of the motor M via a connection terminal BR1, and is connected to the negative terminal of the motor M via a connection terminal BR2.

[0015] When the motor M is rotated in the forward direction, the control circuit 10 turns on the first high-side transistor QH1 and the second low-side transistor QL2, and turns on the second high-side transistor When rotating the motor M in the reverse direction, the control circuit 10 controls the second high-side transistor QH2 and the first low-side transistor QL1 to be on and the first high-side transistor QH1 and the second low-side transistor QL2 to be off. A more detailed control method for the rotation operation of the motor M can be an existing method such as the method described in Patent Document 1 (JP Patent Publication 2021-29084), and will not be described here.

[0016] Next, the configuration of the brake circuit 13 provided in the control circuit 10 of the motor driver 1 according to the embodiment will be described with reference to Fig. 2. Fig. 2 is a circuit diagram of the brake circuit 13. In a brake mode in which the rotation of the motor M is stopped, the brake circuit 13 is used to maintain the stopped state of the motor M by connecting the + and - terminals of the motor M to the ground potential GND to provide a short brake. Note that the potential to which the + and - terminals of the motor M are connected is not limited to the ground potential GND, and may be any potential that allows the motor M to be maintained in the stopped state.

[0017] In Fig. 2, the half-bridge output stage has a common configuration to both the first half-bridge output stage and the second half-bridge output stage, and therefore is simplified from Fig. 1 by using a high-side transistor QH, a low-side transistor QL, a connection terminal BR, a terminal GH, and a terminal GL. A high-side drive circuit 11 that controls the high-side transistor QH is connected to the terminal GH that is connected to the control electrode of the high-side transistor QH. A low-side drive circuit 12 that controls the low-side transistor QL is connected to the terminal GL that is connected to the control electrode of the low-side transistor QL. The connection point between the high-side transistor QH and the low-side transistor QL is connected to the connection terminal BR and the terminal of the motor M.

[0018] The brake circuit 13 is configured as follows. A first electrode of the first switch S1 is connected to the connection terminal BR via a resistor R7, and a second electrode of the first switch S1 is connected to the ground potential GND. The control electrode of the first switch S1 is connected to the output terminal of the comparator C1. A first electrode of the second switch S2 is connected to the control electrode of the first switch S1, and a second electrode of the second switch S2 is connected to the ground potential GND. The control electrode of the second switch S2 is connected to the terminal EN via an inverter 21. A series circuit of resistors R4, R5, and R6 is connected between the connection terminal BR and the ground potential GND. The third switch S3 has a first electrode connected to the connection point of the resistors R5 and R6, a second electrode connected to the ground potential GND, and a control electrode connected to the output terminal of the comparator C1. For example, an N-channel MOSFET can be used for the first switch S1, the second switch S2, and the third switch S3. A series circuit of resistors R1, R2, and R3 is connected between the terminal SB and the ground potential GND. The fourth switch S4 has a first electrode connected to the ground potential GND, a second electrode connected to the connection point between the resistors R4 and R5 and the inverting input terminal - of the comparator C1, and a control electrode connected to the connection point between the resistors R1 and R2. For example, a P-channel MOSFET can be used for the fourth switch S4. The non-inverting input terminal + of the comparator C1 is connected to the connection point between the resistors R2 and R3. The positive power supply terminal of the comparator C1 is connected to the terminal SB via the DC current source 22, and the negative power supply terminal is connected to the ground potential GND.

[0019] The setting circuit 20 includes the comparator C1, the third switch S3, the fourth switch S4, and the resistors R1 to R6 configured as described above. The setting circuit 20 monitors the terminal voltage V1 input from the connection terminal BR to the brake circuit 13, and controls the on / off of the first switch S1 in response to the terminal voltage V1.

[0020] Next, the operation of the motor driver 1 in the brake mode will be explained with reference to Figs. 2, 3 and 4. Fig. 3 is a diagram showing the relationship between the terminal voltage V1 and the signal voltage V2 input to the inverting input terminal - of the comparator C1 in the brake mode of the motor driver 1. Fig. 4 is a diagram showing the relationship between the terminal voltage V1 and the output voltage V3 of the comparator C1 in the brake mode of the motor driver 1.

[0021] When the motor driver 1 is operated in the brake mode, the operation switching voltage Ven input to the terminal EN is Vh2 (HI potential, for example, 5 V), and a predetermined control voltage Vsb is input to the terminal SB.

[0022] Since the operation switching voltage Ven is Vh2, the operation switching voltage Ven is inverted by the inverter 21, and the voltage V4 input to the control electrode of the second switch S2 is zero (LO potential), so that the second switch S2 is in the OFF state. Since the second switch S2 is in the OFF state, the first switch S1 and the third switch S3 are in a state that can be controlled by the output voltage V3 of the comparator C1.

[0023] When a predetermined control voltage Vsb is input to the terminal SB, a predetermined reference voltage Vr=Vsb×R3 / (R1+R2+R3) is input to the non-inverting input terminal + of the comparator C1. In addition, Vsb×(R2+R3) / (R1+R2+R3) is input to the control electrode of the fourth switch S4. This makes it possible to suppress the maximum value of the signal voltage V2 input to the inverting input terminal − of the comparator C1 by the clamp voltage Vc=Vsb×(R2+R3) / (R1+R2+R3)+Vs4. Here, Vs4 is the threshold voltage of the fourth switch S4. By setting the clamp voltage Vc in this way, the brake circuit 13 can be protected from high voltage. When it is not necessary to set the clamp voltage Vc, the fourth switch S4 can be omitted.

[0024] Then, to start the brake mode, the control circuit 10 shuts down the high-side drive circuit 11 to turn off the high-side transistor QH, and turns on the low-side transistor QL by the low-side drive circuit 12. Then, the terminal voltage V1 drops toward zero, and the rotation of the motor M stops. When the terminal voltage V1 starts to drop, the control circuit 10 turns off the low-side transistor QL by the low-side drive circuit 12.

[0025] When the terminal voltage V1 is large and V1×(R5+R6) / (R4+R5+R6) is greater than the clamp voltage Vc, the voltage value of the signal voltage V2 is suppressed by the clamp voltage Vc, as shown in section (1) of Figure 3. Then, when the terminal voltage V1 continues to drop and V1×(R5+R6) / (R4+R5+R6) becomes equal to or less than the clamp voltage Vc, the signal voltage V2=V1×(R5+R6) / (R4+R5+R6) becomes equal to or less than the clamp voltage Vc, as shown in section (2) of Figure 3.

[0026] Then, when the terminal voltage V1 drops to the first set voltage Vth1, the signal voltage V2 becomes smaller than the reference voltage Vr input to the non-inverting input terminal + of the comparator C1. Then, as shown in Fig. 4, the output voltage V3 of the comparator C1 switches from zero (LO potential) to Vh1 (HI potential, for example, 5V), turning on the first switch S1 and the third switch S3. When the first switch S1 turns on, the connection terminal BR is connected to the ground potential GND via the resistor R7, the terminal voltage V1 becomes zero, and the motor M enters a short brake state.

[0027] Furthermore, when the third switch S3 is turned on, as shown in section (3) of FIG. 3, the signal voltage V2 input to the inverting input terminal - of the comparator C1 is switched to V2 = V1 × R5 / (R4 + R5). As a result, when the terminal voltage V1 rises, a second set voltage Vth2 that is higher than the first set voltage Vth1 is set as a set voltage that can turn off the first switch S1. By setting the first set voltage Vth1 and the second set voltage Vth2 to different values, the comparator This makes it possible to prevent chattering from occurring in the output voltage V3 when the output voltage V3 of the converter C1 switches from zero to Vh1 or from Vh1 to zero.

[0028] According to the brake circuit 13, since the connection terminal BR is connected to the ground potential GND via the resistor R7, it is possible to maintain a short brake on the motor M with the low-side transistor QL turned off. If the short brake on the motor M is maintained by turning on the low-side transistor QL, circuits such as an internal power supply or a gate drive circuit for turning on the low-side transistor QL operate, resulting in current consumption on the order of several mA. In contrast, the brake circuit 13 can maintain the short brake on the motor M with the low-side transistor QL turned off, so it is possible to suppress the current consumption due to the operation of the low-side transistor QL.

[0029] Furthermore, when the terminal voltage V1 is large, if the first switch S1 formed of an N-channel MOSFET is turned on and suddenly connected to the ground potential GND, there is a concern that the first switch S1 may be destroyed. For this reason, the setting circuit 20 turns on the first switch S1 when the terminal voltage V1 drops to a predetermined first set voltage Vth1, thereby preventing the first switch S1 from being destroyed.

[0030] Next, the operation when the brake mode of the motor driver 1 is released will be described.

[0031] When the brake mode is released and the operation mode is set to operate the motor M, the operation switching voltage Ven input to the terminal EN is set to zero (LO potential). By setting the operation switching voltage Ven to zero, the operation switching voltage Ven is inverted by the inverter 21, and the voltage V4 input to the control electrode of the second switch S2 becomes HI potential (for example, 5 V), so that the second switch S2 is switched on. When the second switch S2 is turned on, the control electrodes of the first switch S1 and the third switch S3 are connected to the ground potential GND, so that the first switch S1 and the third switch S3 are always off and switching operations are disabled regardless of the output voltage V3 of the comparator C1. As a result, in the operation mode, the operation of the brake circuit 13 is disabled regardless of the value of the terminal voltage V1, and it is possible to prevent the motor M from entering a short brake state.

[0032] When the high-side transistor QH is turned on, the terminal voltage V1 starts to rise from zero. At this time, as shown in section (3) of Figure 3, the signal voltage V2 = V1 × R5 / (R4 + R5) is input to the inverting input terminal - of the comparator C1.

[0033] When the terminal voltage V1 rises to a second set voltage Vth2 that is greater than the first set voltage Vth1, the signal voltage V2 becomes greater than the reference voltage Vr input to the non-inverting input terminal + of the comparator C1, and the output voltage V3 of the comparator C1 switches from Vh1 (HI potential) to zero (LO potential).

[0034] The value of the control voltage Vsb and the resistance values ​​of the resistors R1 to R7 can be set arbitrarily according to the values ​​of the desired clamp voltage Vc, signal voltage V2, reference voltage Vr, first set voltage Vth1, and second set voltage Vth2. In addition, an example has been shown in which the setting circuit 20 generates the reference voltage Vr and the clamp voltage Vc by dividing the control voltage Vsb with the resistors R1 to R3, and the signal voltage V2 by dividing the terminal voltage V1 with the resistors R4 to R6, but this is not limiting. The setting circuit 20 only needs to turn on the first switch S1 when the terminal voltage V1 drops to the predetermined first set voltage Vth1, and the configuration can be arbitrarily determined by the designer.

[0035] According to the motor driver 1 according to the embodiment, in the brake mode, the brake circuit In FIG. 13, by turning on the first switch S1, the connection terminal BR, which is the connection point between the high-side transistor QH and the low-side transistor QL, is connected to the ground potential GND via the resistor R7. By connecting the connection terminal BR to the ground potential GND via the resistor R7, the motor M can be put into a short brake state. Therefore, the high-side transistor QH and the low-side transistor QL can be turned off to suppress current consumption, and the motor M can be kept in a stopped state with low current consumption.

[0036] According to the motor driver 1 according to the embodiment, in the brake mode, the setting circuit 20 in the brake circuit 13 turns on the first switch S1 when the terminal voltage V1 drops to a predetermined first set voltage Vth1, thereby making it possible to prevent the first switch S1 from being destroyed.

[0037] The brake circuit 13 can be built in, for example, a pre-driver IC (Integrated Circuit) used to drive an H-bridge circuit. By building the brake circuit 13 in the pre-driver IC, the mounting area can be reduced compared to when only the brake circuit 13 is configured as an IC, and the current consumption and manufacturing costs can be reduced.

[0038] (Appendix 1) The motor driver 1 drives a motor M and includes a half-bridge output stage configured with a high-side transistor QH and a low-side transistor QL, the motor M being connected to a connection terminal BR to which the high-side transistor QH and the low-side transistor QL are connected, and a control circuit 10 that monitors a terminal voltage V1 of the connection terminal BR. The control circuit 10 turns off the high-side transistor QH and turns on the low-side transistor QL to start a brake mode that stops the motor M, and in the brake mode, when the terminal voltage V1 is lower than a first set voltage Vth1, connects the connection terminal BR to a potential that can maintain the stopped state of the motor M with the high-side transistor QH and the low-side transistor QL turned off.

[0039] In the brake mode, by turning off the high-side transistor QH and the low-side transistor QL and connecting the connection terminal BR to a potential at which the motor M can be maintained in a stopped state, the motor M can be maintained in a stopped state with low current consumption.

[0040] (Appendix 2) In the motor driver 1 described in Supplementary Note 1, the control circuit 10 includes a brake circuit 13 that maintains a stopped state of the motor M. The brake circuit 13 includes a switch S1 having a first electrode connected to a connection terminal BR via a resistor R7 and a second electrode connected to a ground potential GND, and a setting circuit 20 that controls the on / off of the switch S1 in response to a terminal voltage V1. In the brake mode, the setting circuit 20 turns on the switch S1 when it detects that the terminal voltage V1 has dropped to a first set voltage Vth1.

[0041] When the setting circuit 20 detects that the terminal voltage V1 has dropped to the first set voltage Vth1 in the brake mode, it turns on the switch S1, thereby connecting the connection terminal BR to the ground potential GND via the resistor R7, and maintaining the drive of the motor M in a stopped state.

[0042] (Appendix 3) In the motor driver 1 described in Supplementary Note 2, when the setting circuit 20 detects that the terminal voltage V1 has dropped to the first set voltage Vth1 in the brake mode, it turns on the switch S1, and sets the set voltage at which the switch S1 can be turned off when the terminal voltage V1 rises. The voltage Vth1 is set to a second set voltage Vth2 which is higher than the first set voltage Vth1.

[0043] By setting the second set voltage Vth2 to a value greater than the first set voltage Vth1, it is possible to prevent chattering from occurring when the switch S1 switches between off and on.

[0044] (Appendix 4) In the motor driver 1 described in Supplementary Note 2 or 3, the control circuit 10 turns off the switch S1 when releasing the brake mode.

[0045] When the brake mode is released, the switch S1 is turned off, and the short brake state of the motor M is released.

[0046] (Appendix 5) In the motor driver 1 described in Supplementary Note 4, in an operation mode in which the brake mode is released, the switch S1 is always off.

[0047] Since the switch S1 is always off in the operation mode, even if the setting circuit 20 operates in the operation mode, the motor M can be prevented from going into a short brake state.

[0048] (Appendix 6) In the motor driver 1 described in any one of Supplementary Notes 1 to 5, the control circuit 10 includes a high-side drive circuit 11 that drives the high-side transistor QH. When the control circuit 10 transitions to the brake mode, it shuts down the high-side drive circuit 11 to cause the terminal voltage V1 to decrease toward zero.

[0049] Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described in the present disclosure. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and does not have any limiting meaning on the present disclosure. [Explanation of symbols]

[0050] 1 Motor driver 10 Control circuit 11, 11-1, 11-2 High side drive circuit 12, 12-1, 12-2 Low side drive circuit 13 Brake circuit 20 Setting circuit 21 Inverter 22 DC current source BR connection terminal C1 Comparator GND Ground potential (earth potential) Medium motor QH, QH1, QH2 High-side transistors QL, QL1, QL2 low-side transistors R1,R2,R3,R4,R5,R6,R7 Resistor S1 1st switch (switch) S2 Second switch S3 3rd switch S4 4th switch V1 terminal voltage V2 signal voltage V3 Comparator C1 output voltage Ven operation switching voltage Vr Reference voltage Vsb Control voltage Vth1 First set voltage Vth2 Second set voltage

Claims

1. A motor driver that drives a motor, a half-bridge output stage including a high-side transistor and a low-side transistor, the motor being connected to a connection terminal connecting the high-side transistor and the low-side transistor; A control circuit that monitors a terminal voltage of the connection terminal; Equipped with The control circuit includes: turning off the high-side transistor and turning on the low-side transistor to start a brake mode in which the motor is stopped; in the brake mode, when the terminal voltage is lower than a first set voltage, the high-side transistor and the low-side transistor are turned off and the connection terminal is connected to a potential capable of maintaining a stopped state of the motor. Motor driver.

2. the control circuit includes a brake circuit that maintains the motor in a stopped state; The brake circuit includes: a switch having a first electrode connected to the connection terminal via a resistor and a second electrode connected to a ground potential; a setting circuit for controlling the switch to be turned on and off in response to the terminal voltage; Equipped with When the setting circuit detects that the terminal voltage has dropped to the first set voltage in the brake mode, the setting circuit turns on the switch. The motor driver according to claim 1 .

3. 3. The motor driver according to claim 2, wherein when the setting circuit detects that the terminal voltage has dropped to the first set voltage in the braking mode, it turns on the switch, and sets a second set voltage higher than the first set voltage as a set voltage at which the switch can be turned off when the terminal voltage rises.

4. When the brake mode is released, the control circuit turns off the switch.

4. The motor driver according to claim 2 or 3.

5. 5. The motor driver according to claim 4, wherein the switch is always off when the motor driver is in an operation mode in which the brake mode is released.

6. the control circuit includes a high-side drive circuit that drives the high-side transistor; When the control circuit transitions to the brake mode, the control circuit shuts down the high side drive circuit, thereby causing the terminal voltage to decrease toward zero. The motor driver according to claim 1 .

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