Direct-current brushless motor driving circuit and driving method

Abstract

The invention discloses a direct current brushless motor driving circuit and a driving method, the direct current brushless motor driving circuit comprises an MCU, a driving circuit, a protection circuit and a winding, the MCU is connected with the driving circuit and the protection circuit, the driving circuit is connected with the winding, the MCU is used for feeding back PWM signals to the driving circuit and the protection circuit, the driving circuit is used for converting signals and providing variable current directions for the motor winding, and the winding is connected with the protection circuit. And the protection circuit is used for setting a dead zone interval and performing corresponding warning feedback according to a control signal output by the MUC. According to the invention, by setting the independent and dynamically adjustable dead zone interval, the adaptability to an aged MOS tube can be improved, and when a logic error is caused by program fleeting of the MCU or the output of an I / O port of the MCU due to instantaneous interference, the MCU can be protected from the dead zone interval. And a warning signal is output to the MCU and a peripheral DC power supply circuit, so that bridge arm direct connection caused by wrong feedback of the control signal is prevented.

Description

A DC brushless motor drive circuit and driving method Technical Field

[0001] This invention relates to the field of brushless DC motor technology, and in particular to a brushless DC motor drive circuit and driving method. Background Technology

[0002] The drive circuit of a brushless DC motor typically consists of three parts: an MCU, a drive circuit, and motor windings. During operation, the MCU outputs PWM signals in a predetermined sequence. These signals are amplified by a gate driver chip to control the on / off state of the corresponding MOSFETs in the three-phase full-bridge circuit. Through commutation, controlled three-phase AC current is output to the windings, thereby controlling the motor speed and torque. Existing gate driver chips have built-in dead-time protection to prevent bridge arm shoot-through. However, the built-in dead-time protection usually has a fixed delay and cannot determine if there is a logic error in the MCU. As the switching speed of the MOSFETs decreases due to their lifespan, the fixed dead-time cannot adapt to the current switching speed of the MOSFETs. Therefore, a brushless DC motor drive circuit is proposed. This circuit improves the adaptability to aged MOSFETs by setting an independent and dynamically adjustable dead-time interval. Furthermore, when the MCU experiences a logic error due to program crashes or momentary interference to its I / O ports, an alarm signal is output to the MCU and the external DC power supply circuit to prevent bridge arm shoot-through caused by erroneous feedback of the control signal. Summary of the Invention

[0003] To address the aforementioned technical problems, the present invention aims to provide a DC brushless motor drive circuit and driving method, comprising an MCU, a drive circuit, a protection circuit, and a winding. The MCU is connected to the drive circuit and the protection circuit, and the drive circuit is connected to the winding. The MCU is used to provide PWM signals to the drive circuit and the protection circuit. The drive circuit is used to convert signals and provide variable current direction to the motor winding. The protection circuit is used to set a dead zone and provide corresponding alarm feedback based on the control signal output by the MCU.

[0004] Furthermore, the protection circuit includes a protection unit comprising operational amplifiers U4, U5, and U6, diodes D4, D5, D6, and D9, capacitors C4, C5, and C6, an adjustable potentiometer R7, resistors R8 and R9, adjustable potentiometers R10, R11, R12, and R13, and resistors R14 and R15. The non-inverting input of operational amplifier U4 is connected to the cathode of diode D4 and one end of capacitor C5, while its inverting input is connected to one end of resistor R8 and one end of resistor R9. The non-inverting input of operational amplifier U5 is connected to the output terminal of operational amplifier U6 and one end of resistor R14, while its inverting input is connected to one end of adjustable potentiometer R12 and one end of adjustable potentiometer R13. The output terminal is connected to diode D4. Anode of diode D6, the other end of adjustable potentiometer R12; the other end of resistor R14 at the inverting input of op-amp U6, and one end of resistor R15; one end of capacitor C4 is connected to the other end of resistor R15, and the other end is connected to one end of adjustable potentiometer R7 and one end of adjustable potentiometer R11; anode of diode D4, the other end of resistor R8 is connected to the power supply; anode of diode D5 is connected to PWM2, and cathode is connected to the cathode of diode D9 and the other end of adjustable potentiometer R11; cathode of diode D6 is connected to the other end of capacitor C5, one end of capacitor C6, and one end of adjustable potentiometer R10; anode of diode D9 is connected to PWM1; the non-inverting input of op-amp U6, the other end of capacitor C6, the other end of adjustable potentiometer R7, the other end of resistor R9, the other end of adjustable potentiometer R10, and the other end of adjustable potentiometer R13 are grounded.

[0005] Furthermore, the protection circuit also includes an alarm unit, which includes transistors Q7, Q8, and Q9, diodes D7 and D8, resistors R16, R17, and R18. The base of transistor Q7 is connected to the cathodes of diodes D7 and D8, and one end of resistor R16; the emitter is connected to one end of resistor R17; and the collector is connected to the bases of transistors Q8 and Q9. The emitter of transistor Q8 is connected to PWM1; the emitter of transistor Q9 is connected to the anode of diode D7 and PWM2; the anode of diode D8 is connected to the output of operational amplifier U4; the collector of transistor Q8 is connected to the collector of transistor Q9 and one end of resistor R18; and the other ends of resistors R16, R17, and R18 are grounded.

[0006] Furthermore, the driving circuit includes gate driver chip U1, gate driver chip U2, gate driver chip U3, MOSFETs Q1, Q2, Q3, Q4, Q5, and Q6, diodes D1, D2, and D3, capacitors C1, C2, and C3, resistors R1, R2, R3, R4, R5, and R6. The LO terminal of gate driver chip U1 is connected to one end of resistor R2, the VS terminal is connected to one end of capacitor C1, the source of MOSFET Q1, and the drain of MOSFET Q2, the HO terminal is connected to one end of resistor R1, and the VB terminal is connected to the cathode of diode D1 and the other end of capacitor C1. The LO terminal of gate driver chip U2 is connected to one end of resistor R4, the VS terminal is connected to one end of capacitor C2, the source of MOSFET Q3, and the drain of MOSFET Q4, the HO terminal is connected to one end of resistor R3, and the VB terminal is connected to the cathode of diode D2 and the other end of capacitor C2. The LO terminal of gate driver chip U3 is connected to one end of resistor R6, the VS terminal is connected to one end of resistor R4, the VS terminal is connected to one end of capacitor C2, the source of MOSFET Q3, and the drain of MOSFET Q4, the HO terminal is connected to one end of resistor R3, and the VB terminal is connected to the cathode of diode D2 and the other end of capacitor C2. The S terminal is connected to one end of capacitor C3, the source of MOSFET Q5, and the drain of MOSFET Q6. The HO terminal is connected to one end of resistor R5. The VB terminal is connected to the cathode of diode D3 and the other end of capacitor C3. The gate of MOSFET Q1 is connected to the other end of resistor R1. The gate of MOSFET Q2 is connected to the other end of resistor R2. The gate of MOSFET Q3 is connected to the other end of resistor R3. The gate of MOSFET Q4 is connected to the other end of resistor R4. The gate of MOSFET Q5 is connected to the other end of resistor R5. The gate of MOSFET Q6 is connected to the other end of resistor R6. The VCC terminals of gate driver chips U1, U2, and U3, the anodes of diodes D1, D2, and D3, the drains of MOSFETs Q1, Q3, and Q5 are connected to the power supply. The COM terminals of gate driver chips U1, U2, and U3, the sources of MOSFETs Q2, Q4, and Q6 are grounded.

[0007] Furthermore, the driving method of the DC brushless motor drive circuit including any of the above includes the following steps: Step 1: The MCU outputs PWM signals to the drive circuit in a predetermined order. The drive circuit controls the conduction and cutoff of the corresponding MOSFET according to the PWM signal to provide a variable current direction for the motor winding to form a rotating magnetic field; Step 2: The protection circuit monitors when the drive circuit receives the PWM signal. If the high-voltage side control terminal and the low-voltage side control terminal of the same bridge arm simultaneously receive the PWM control signal, an alarm signal is output to the MCU and the peripheral DC power supply circuit; Step 3: A dead zone is established when either side of the bridge arm receives the PWM signal and it is located at the falling edge. The PWM signal is monitored on both sides within the dead zone. When a PWM signal is received on either side within the dead zone, an alarm signal is output to the MCU and the peripheral DC power supply circuit.

[0008] The beneficial effects of this invention compared with the prior art are: this invention can improve the adaptability of aged MOS transistors by setting an independent and dynamically adjustable dead zone interval, and when the MCU causes a logic error due to program crash or instantaneous interference to its I / O port output, it can output an alarm signal to the MCU and the peripheral DC power supply circuit to prevent bridge arm shoot-through caused by false feedback of control signals. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 is a schematic diagram of the overall structure provided by the present invention.

[0011] Figure 2 is a schematic diagram of the protection circuit structure provided by the present invention. Detailed Implementation

[0012] To make the objectives and advantages of the present invention clearer, the present invention will be specifically described below in conjunction with embodiments. It should be understood that the following text is only used to describe one or more specific embodiments of the present invention and does not strictly limit the scope of protection specifically claimed by the present invention.

[0013] This invention discloses a DC brushless motor drive circuit and driving method, including an MCU, a drive circuit, a protection circuit, and a winding. The MCU is connected to the drive circuit and the protection circuit, and the drive circuit is connected to the winding. The MCU is used to feed back PWM signals to the drive circuit and the protection circuit. The drive circuit is used to convert signals and provide variable current direction to the motor winding. The protection circuit is used to set the dead zone and provide corresponding alarm feedback based on the control signal output by the MCU.

[0014] Specifically, the protection circuit includes a protection unit, which comprises operational amplifiers U4, U5, and U6, diodes D4, D5, D6, and D9, capacitors C4, C5, and C6, an adjustable potentiometer R7, resistors R8 and R9, adjustable potentiometers R10, R11, R12, and R13, and resistors R14 and R15. The non-inverting input of operational amplifier U4 is connected to the cathode of diode D4 and one end of capacitor C5, while the inverting input is connected to one end of resistor R8 and one end of resistor R9. The non-inverting input of operational amplifier U5 is connected to the output terminal of operational amplifier U6 and one end of resistor R14, while the inverting input is connected to one end of adjustable potentiometer R12 and one end of adjustable potentiometer R13. The output terminal is connected to diode D7. 6. Anode, the other end of adjustable potentiometer R12; the other end of resistor R14 at the inverting input of op-amp U6, and one end of resistor R15; one end of capacitor C4 is connected to the other end of resistor R15, and the other end is connected to one end of adjustable potentiometer R7 and one end of adjustable potentiometer R11; anode of diode D4, the other end of resistor R8 is connected to the power supply; anode of diode D5 is connected to PWM2, cathode is connected to the cathode of diode D9 and the other end of adjustable potentiometer R11; cathode of diode D6 is connected to the other end of capacitor C5, one end of capacitor C6, and one end of adjustable potentiometer R10; anode of diode D9 is connected to PWM1; non-inverting input of op-amp U6, the other end of capacitor C6, the other end of adjustable potentiometer R7, the other end of resistor R9, the other end of adjustable potentiometer R10, and the other end of adjustable potentiometer R13 are grounded.

[0015] Specifically, the protection circuit further includes an alarm unit, which includes transistors Q7, Q8, and Q9, diodes D7 and D8, resistors R16, R17, and R18. The base of transistor Q7 is connected to the cathodes of diodes D7 and D8, and one end of resistor R16; the emitter is connected to one end of resistor R17; and the collector is connected to the bases of transistors Q8 and Q9. The emitter of transistor Q8 is connected to PWM1; the emitter of transistor Q9 is connected to the anode of diode D7 and PWM2; the anode of diode D8 is connected to the output of operational amplifier U4; the collector of transistor Q8 is connected to the collector of transistor Q9 and one end of resistor R18; and the other ends of resistors R16, R17, and R18 are grounded.

[0016] Specifically, the driving circuit includes gate driver chip U1, gate driver chip U2, gate driver chip U3, MOSFETs Q1, Q2, Q3, Q4, Q5, and Q6, diodes D1, D2, and D3, capacitors C1, C2, and C3, resistors R1, R2, R3, R4, R5, and R6. The LO terminal of gate driver chip U1 is connected to one end of resistor R2, the VS terminal is connected to one end of capacitor C1, the source of MOSFET Q1, and the drain of MOSFET Q2, the HO terminal is connected to one end of resistor R1, and the VB terminal is connected to the cathode of diode D1 and the other end of capacitor C1. Similarly, the LO terminal of gate driver chip U2 is connected to one end of resistor R4, the VS terminal is connected to one end of capacitor C2, the source of MOSFET Q3, and the drain of MOSFET Q4, the HO terminal is connected to one end of resistor R3, and the VB terminal is connected to the cathode of diode D2 and the other end of capacitor C2. The LO terminal of gate driver chip U3 is connected to one end of resistor R6, and the VS terminal is connected to the source of MOSFET Q3 and the drain of MOSFET Q4, the HO terminal is connected to one end of resistor R3, and the VB terminal is connected to the cathode of diode D2 and the other end of capacitor C2. The S terminal is connected to one end of capacitor C3, the source of MOSFET Q5, and the drain of MOSFET Q6. The HO terminal is connected to one end of resistor R5. The VB terminal is connected to the cathode of diode D3 and the other end of capacitor C3. The gate of MOSFET Q1 is connected to the other end of resistor R1. The gate of MOSFET Q2 is connected to the other end of resistor R2. The gate of MOSFET Q3 is connected to the other end of resistor R3. The gate of MOSFET Q4 is connected to the other end of resistor R4. The gate of MOSFET Q5 is connected to the other end of resistor R5. The gate of MOSFET Q6 is connected to the other end of resistor R6. The VCC terminals of gate driver chips U1, U2, and U3, the anodes of diodes D1, D2, and D3, the drains of MOSFETs Q1, Q3, and Q5 are connected to the power supply. The COM terminals of gate driver chips U1, U2, and U3, the sources of MOSFETs Q2, Q4, and Q6 are grounded.

[0017] Specifically, the driving method of the DC brushless motor drive circuit including any of the above includes the following steps: Step 1: The MCU outputs PWM signals to the drive circuit in a predetermined order. The drive circuit controls the conduction and cutoff of the corresponding MOS transistor according to the PWM signal to provide a variable current direction for the motor winding to form a rotating magnetic field; Step 2: The protection circuit monitors when the drive circuit receives the PWM signal. If the high-voltage side control terminal and the low-voltage side control terminal of the same bridge arm simultaneously receive the PWM control signal, an alarm signal is output to the MCU and the peripheral DC power supply circuit; Step 3: A dead zone is established when either side of the bridge arm receives the PWM signal and it is located at the falling edge. The PWM signal is monitored on both sides within the dead zone. When a PWM signal is received on either side within the dead zone, an alarm signal is output to the MCU and the peripheral DC power supply circuit.

[0018] The HIN terminal of gate driver chips U1 to U3 is the high-voltage side control terminal, the LIN terminal is the low-voltage side control terminal, VB is the power supply floating terminal, VS is the power supply stabilizing terminal, VCC is the power supply terminal, the HO terminal is the floating drive terminal, and the LO terminal is the stabilizing drive terminal. Three bridge arms are formed by MOSFETs Q1 to Q6. The midpoint of each bridge arm is connected to the power supply stabilizing terminal of gate driver chips U1 to U3 and one phase winding (A, B, C) of the motor, respectively. MOSFETs Q1, Q3, and Q5 are the high-side MOSFETs of the bridge arm, and MOSFETs Q2, Q4, and Q6 are the low-side MOSFETs of the bridge arm. The HO terminal of gate driver chips U1 to U3 is used to drive the high side of the upper bridge arm, and the LO terminal is used to drive the low side of the lower bridge arm. The HO terminal signal is input to the gate of MOSFETs Q1, Q3, and Q5 through resistors R1, R3, and R5, respectively, and the LO terminal signal is input through resistors R2, R4, and R6, respectively. Resistors R1 to R6 are used to limit the gate current of MOSFETs Q1 to Q6. Capacitors C1, C2, and C3 are connected between VB and VS of gate driver chips U1, U2, and U3, respectively. Capacitors C1 to C3 are bootstrap capacitors, and diodes D1 to D3 are bootstrap diodes. The power supply charges the bootstrap capacitors through the bootstrap diodes to ensure reliable conduction of the high-side MOSFETs. The MCU inputs PWM1 to PWM6 signals to the HIN and LIN terminals of gate driver chips U1 to U3, respectively. The HO and LO terminals control the conduction of the upper and lower MOSFETs of the three bridge arms to provide variable current direction to the motor windings to form a rotating magnetic field. When the lower bridge is on, the power supply charges the bootstrap capacitors through the bootstrap diodes, and the capacitor voltage is close to the power supply voltage. When the upper bridge is on, the negative terminal (VS terminal) of the capacitor rises with the phase line voltage, and the positive terminal voltage of the capacitor rises to maintain the voltage difference required for the upper bridge to conduct.

[0019] The protection circuit includes three protection units and three alarm units. Gate driver chips U1, U2, and U3 are connected to one protection unit and one alarm unit, respectively. Diode D9 receives the signal from the high-voltage side control terminal at its anode, and diode D5 receives the signal from the low-voltage side control terminal at its anode. When the signal from either the high-voltage or low-voltage side control terminal is at a rising edge, the signal passes through diode D9 or D5, then through adjustable potentiometers R11 and R7, and is fed back to the positive terminal of capacitor C4. The negative terminal voltage rises positively and then quickly drops to zero potential. Adjusting the resistance values ​​of adjustable potentiometers R11 and R7, or adjusting the capacitance value of capacitor C4, to make the signal on either side high, the capacitor... The time it takes for capacitor C4 to rise and fall to zero potential is less than the high-level time of the PWM signal on either side. Op-amp U6, resistors R15 and R14 form an inverter. When the negative terminal of capacitor C4 is positive, op-amp U6 has no output. When the control signal on that side is a rising edge, the positive terminal of capacitor C4 is at ground potential, pulling the negative terminal of C4 to a negative voltage. Op-amp U6 then inverts and follows the output. The output signal of op-amp U6 is fed back to the non-inverting input of op-amp U5. Op-amp U5, adjustable potentiometers R12 and R13 form an inverting amplifier. Op-amp U5 amplifies the output signal of op-amp U6. The power supply signal, via diode D4, provides the power supply voltage to the positive terminal of capacitor C5. The signal at the positive terminal of capacitor C5 serves as the dead-time reference signal. The DC power supply signal... The signal is fed back to the inverting input of op-amp U4 via a voltage divider connected to resistors R8 and R9. Adjusting the values ​​of resistors R8 and R9 makes the signal at the inverting input of op-amp U4 slightly higher than the dead-time reference signal. When op-amp U5 outputs, the output signal of op-amp U5 is fed back to the negative terminal of capacitor C5 and the positive terminal of capacitor C6 via diode D6, simultaneously raising the voltage at the positive terminal of capacitor C5. When op-amp U5 has no output, the signal at the positive terminal of capacitor C6 is grounded via adjustable potentiometer R10, while the voltage at the positive terminal of capacitor C5 gradually decreases to the supply voltage. Adjusting the amplification ratio of op-amp U5 changes the magnitude of the voltage rise at the positive terminal of capacitor C5 when op-amp U5 outputs. When the voltage at the positive terminal of capacitor C5 rises and exceeds the dead-time reference signal, op-amp U4 outputs; when the voltage at capacitor C5 drops to the supply voltage, op-amp U4 is cut off. 4. The time from output to cutoff is the dead zone. After obtaining a PWM signal on either side, the dead zone is entered. Adjusting the resistance values ​​of adjustable potentiometers R12 and R13 changes the amplification ratio of op-amp U5. Adjusting the resistance value of adjustable potentiometer R10 changes the rate at which the voltage drop at the positive terminal of capacitor C5 changes when op-amp U5 has no output. The dead time is set by adjusting the amplification ratio and the rate at which the voltage drop at the positive terminal of capacitor C5. The resistance values ​​of adjustable potentiometers R12, R13, and R10 are adaptively adjusted by the MCU based on the aging degree of the MOSFET. The aging degree of the MOSFET is detected by an external detection circuit. In this way, the adaptability to the switching speed of the aged MOSFET is improved through an independent and dynamically adjustable dead zone.

[0020] During non-dead time, if both the high-voltage and low-voltage control terminals receive signals simultaneously, the low-voltage control terminal signal passes through diode D7, the base of transistor Q7, the emitter of transistor Q7, and resistor R17 to ground, turning on transistor Q7. Conversely, the high-voltage control terminal signal passes through the emitter of transistor Q8, the base of transistor Q8, the collector of transistor Q7, the emitter of transistor Q7, and resistor R17 to ground, turning on transistor Q8. The high-voltage control terminal signal then passes through the emitter and collector of transistor Q8... Electrode and resistor R18 are connected to ground. The signal at resistor R18 outputs an alarm signal to the MCU and the external DC power supply circuit. During the dead time, if the low-voltage side control terminal receives a signal, the signal at the output terminal of operational amplifier U4 passes through diode D8, the base of transistor Q7, the emitter of transistor Q7, and resistor R17 to ground, turning on transistor Q7. The low-voltage side control terminal signal then passes through the emitter of transistor Q9, the base of transistor Q9, the collector of transistor Q7, the emitter of transistor Q7, and resistor R17 to ground. When transistor Q9 is turned on, the low-voltage side control signal passes through the emitter and collector of transistor Q9 and resistor R18 to ground. The signal at resistor R18 outputs an alarm signal to the MCU and the external DC power supply circuit. If the high-voltage side control terminal receives a signal during the dead time, the high-voltage side control signal passes through the emitter and base of transistor Q8, the collector and emitter of transistor Q7, and resistor R17 to ground. When transistor Q8 is turned on, the high-voltage side control signal passes through the emitter and collector of transistor Q8 and resistor R18 to ground. The signal at resistor R18 outputs an alarm signal to the MCU and the external DC power supply circuit. If the MCU does not take corresponding protective action after receiving the alarm signal, the external DC power supply circuit cuts off the DC power supply. This monitors the PWM signals acquired from both sides during the dead time, preventing bridge arm shoot-through caused by false feedback of control signals due to MCU program crashes or instantaneous interference to its I / O port outputs.

[0021] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A DC brushless motor drive circuit, characterized in that, It includes an MCU, a drive circuit, a protection circuit, and windings. The MCU is connected to the drive circuit and the protection circuit, and the drive circuit is connected to the windings. The MCU is used to feed back PWM signals to the drive circuit and the protection circuit. The drive circuit is used to convert signals and provide variable current direction to the motor windings. The protection circuit is used to set the dead zone and provide corresponding alarm feedback based on the control signal output by the MCU.

2. The brushless DC motor drive circuit according to claim 1, characterized in that, The protection circuit includes a protection unit comprising operational amplifiers U4, U5, and U6; diodes D4, D5, D6, and D9; capacitors C4, C5, and C6; an adjustable potentiometer R7; resistors R8 and R9; adjustable potentiometers R10, R11, R12, and R13; and resistors R14 and R15. The non-inverting input of operational amplifier U4 is connected to the cathode of diode D4 and one end of capacitor C5; the inverting input is connected to one end of resistor R8 and one end of resistor R9. The non-inverting input of operational amplifier U5 is connected to the output terminal of operational amplifier U6 and one end of resistor R14; the inverting input is connected to one end of adjustable potentiometer R12 and one end of adjustable potentiometer R13; and the output terminal is connected to the anode of diode D6. The other end of the adjustable potentiometer R12 is connected to the inverting input of op-amp U6; the other end of resistor R14 and one end of resistor R15 are connected to the inverting input of op-amp U6; one end of capacitor C4 is connected to the other end of resistor R15, and the other end is connected to one end of adjustable potentiometer R7 and one end of adjustable potentiometer R11; the anode of diode D4 and the other end of resistor R8 are connected to the power supply; the anode of diode D5 is connected to PWM2, and the cathode is connected to the cathode of diode D9 and the other end of adjustable potentiometer R11; the cathode of diode D6 is connected to the other end of capacitor C5, one end of capacitor C6, and one end of adjustable potentiometer R10; the anode of diode D9 is connected to PWM1; the non-inverting input of op-amp U6, the other end of capacitor C6, the other end of adjustable potentiometer R7, the other end of resistor R9, the other end of adjustable potentiometer R10, and the other end of adjustable potentiometer R13 are grounded.

3. The brushless DC motor drive circuit according to claim 2, characterized in that, The protection circuit also includes an alarm unit, which comprises transistors Q7, Q8, and Q9, diodes D7 and D8, resistors R16, R17, and R18. The base of transistor Q7 is connected to the cathodes of diodes D7 and D8, and one end of resistor R16; the emitter is connected to one end of resistor R17; and the collector is connected to the bases of transistors Q8 and Q9. The emitter of transistor Q8 is connected to PWM1; the emitter of transistor Q9 is connected to the anode of diode D7 and PWM2; the anode of diode D8 is connected to the output of operational amplifier U4; the collector of transistor Q8 is connected to the collector of transistor Q9 and one end of resistor R18; and the other ends of resistors R16, R17, and R18 are grounded.

4. The brushless DC motor drive circuit according to claim 1, characterized in that, The driving circuit includes gate driver chip U1, gate driver chip U2, gate driver chip U3, MOSFETs Q1, Q2, Q3, Q4, Q5, and Q6, diodes D1, D2, and D3, capacitors C1, C2, and C3, resistors R1, R2, R3, R4, R5, and R6. The LO terminal of gate driver chip U1 is connected to one end of resistor R2, the VS terminal is connected to one end of capacitor C1, the source of MOSFET Q1, and the drain of MOSFET Q2, the HO terminal is connected to one end of resistor R1, and the VB terminal is connected to the cathode of diode D1 and the other end of capacitor C1. Similarly, the LO terminal of gate driver chip U2 is connected to one end of resistor R4, the VS terminal is connected to one end of capacitor C2, the source of MOSFET Q3, and the drain of MOSFET Q4, the HO terminal is connected to one end of resistor R3, and the VB terminal is connected to the diode D1.

2. Cathode and the other end of capacitor C2; The LO terminal of gate driver chip U3 is connected to one end of resistor R6, the VS terminal is connected to one end of capacitor C3, the source of MOSFET Q5, the drain of MOSFET Q6, the HO terminal is connected to one end of resistor R5, the VB terminal is connected to the cathode of diode D3 and the other end of capacitor C3; The gate of MOSFET Q1 is connected to the other end of resistor R1; The gate of MOSFET Q2 is connected to the other end of resistor R2; The gate of MOSFET Q3 is connected to the other end of resistor R3; The gate of MOSFET Q4 is connected to the other end of resistor R4; The gate of MOSFET Q5 is connected to the other end of resistor R5; The gate of MOSFET Q6 is connected to the other end of resistor R6; The VCC terminals of gate driver chip U1, gate driver chip U2, and gate driver chip U3, the anode of diode D1, the anode of diode D2, the anode of diode D3, the drain of MOSFET Q1, the drain of MOSFET Q3, and the drain of MOSFET Q5 are connected to the power supply; The COM terminals of gate driver chip U1, U2, and U3, as well as the sources of MOSFETs Q2, Q4, and Q6, are grounded.

5. A driving method for a brushless DC motor drive circuit according to any one of claims 1-4, characterized in that, The process includes the following steps: Step 1: The MCU outputs PWM signals to the drive circuit in a predetermined order. The drive circuit controls the on and off of the corresponding MOSFETs according to the PWM signals to provide a variable current direction for the motor windings to form a rotating magnetic field. Step 2: The protection circuit monitors the drive circuit when it receives the PWM signal. If the high-voltage side control terminal and the low-voltage side control terminal of the same bridge arm simultaneously receive the PWM control signal, an alarm signal is output to the MCU and the peripheral DC power supply circuit. Step 3: A dead zone is established when either side of the bridge arm receives the PWM signal and it is at the falling edge. The system monitors whether the PWM signals are received on both sides within the dead zone. When the PWM signal is received on either side within the dead zone, an alarm signal is output to the MCU and the peripheral DC power supply circuit.

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