Torque motor driving control circuit

Abstract

The invention discloses a torque motor driving control circuit. The circuit comprises an auxiliary power supply module, an ACM32 control system, a DRV8301 drive circuit, a three-phase inverter circuit, a current detection circuit, a three-phase overcurrent protection circuit, a bus voltage detection circuit and a magnetic encoder circuit. Wherein the auxiliary power supply module realizes redundant power supply through an AMS1117 linear voltage regulator or a DRV8301 built-in BUCK circuit; the DRV8301 driving chip integrates the functions of MOS tube driving, BUCK power supply and current amplification, and the circuit structure is simplified; the three-phase overcurrent protection circuit realizes rapid hardware protection based on an LMV331 comparator; the magnetic encoder adopts an MT6826 chip to replace a traditional photoelectric encoder, multi-mode output and SPI configuration are supported, and the detection precision and the integration degree are improved. According to the invention, the response speed and control precision of the system are optimized through modular design, and the stability and reliability are enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor control, and relates to a hardware circuit of a driving system for a torque motor. Background Art

[0002] In the fields of modern industrial automation and intelligent manufacturing, torque motors are widely used in various occasions requiring precise control, such as robots, numerically controlled machine tools, aerospace equipment, etc. due to their advantages of large output torque, fast response speed, high control accuracy, etc. The performance of a torque motor depends to a great extent on the design of its drive control circuit. The torque motor needs to respond to the control signal within an extremely short time to achieve high-precision torque output. It is required that the control circuit can respond quickly to improve the overall performance of the equipment; in high-precision applications, precise control of the torque output is required, which poses higher requirements for the design of the drive circuit, including high-precision sensor feedback and fine signal processing capabilities; the drive circuit needs to operate stably under various working conditions to prevent damage to the motor or other components caused by overload, overcurrent or other abnormal conditions; as the equipment develops towards miniaturization and integration, the drive control circuit also needs to achieve higher functional integration in a limited space. In the existing torque motor drive control circuit, the current sampling circuit uses more components, making the whole system more complex and the circuit volume larger. The MOS tube drive circuit of the existing torque motor drive system often uses three or six independent drive chips, which will also increase the circuit volume, and with the increase of components, the system failure rate will be increased.

[0003] To solve the above problems, the present invention proposes an improved torque motor drive control circuit. The circuit aims to improve the response speed and control accuracy of the torque motor drive system, enhance the stability and reliability of the system, and optimize the integration while achieving high performance. Through innovative circuit design, the present invention can better meet the requirements of modern industrial applications for torque motor drive control. Summary of the Invention

[0004] The purpose of the present invention is to provide a torque motor drive control circuit, which solves the problems existing in the prior art.

[0005] To achieve the above purpose, the present invention is implemented by the following technical solutions: A torque motor drive control circuit includes an auxiliary power supply module, an ACM32 control system, a DRV8301 drive circuit, a three-phase inverter circuit, a current detection circuit, a three-phase overcurrent protection circuit, a bus voltage detection circuit, and a magnetic encoder circuit; The auxiliary power supply module includes an external power supply and a +3.3V power supply voltage stabilization circuit. The +3.3V power supply voltage stabilization circuit generates a +3.3V power supply through the BUCK circuit in the AMS1117 linear voltage regulator or the DRV8301 drive circuit, and realizes power supply switching through the power supply selection circuit; The ACM32 control system is based on the ACM32F403CET7 single-chip microcomputer, communicates with the DRV8301 drive circuit and the magnetic encoder circuit through the SPI interface, and is used to receive sensor signals, output PWM control signals, and configure drive parameters; The DRV8301 drive circuit integrates a MOS tube drive module, a BUCK power supply module, and a high-precision differential current amplification module. The MOS tube drive module of it connects the upper and lower bridge arm MOS tubes of the three-phase inverter circuit through a bootstrap capacitor. The BUCK power supply module outputs a +3.3V voltage through an inductor L2 and a filter capacitor. The current amplification module amplifies the three-phase current sampling signal and inputs it to the ACM32 control system; The three-phase inverter circuit and the current detection circuit include A-phase, B-phase, and C-phase bridge arms. Each phase bridge arm is composed of upper and lower bridge arm MOS tubes and a series-connected sampling resistor. The voltage across the sampling resistor is processed by the DRV8301 current amplification module and then fed back to the ACM32 control system; The magnetic encoder circuit uses an MT6826 magnetic encoder chip, connects to the ACM32 control system through the SPI interface, and outputs ABZ signals to realize motor position detection; The three-phase overcurrent protection circuit is based on an LMV331 comparator, sums the three-phase current sampling signals through an adder and compares them with a reference voltage, outputs an overcurrent fault signal to the ACM32 control system, and at the same time drives a fault indicator light; The bus voltage detection circuit converts the bus voltage into a signal in the range of 0 - 3.3V through a voltage-dividing resistor and a limiting diode, and inputs it to the ACM32 control system.

[0006] The power supply selection circuit includes a 1×3P pin header, and selects the BUCK circuit of the AMS1117 linear voltage regulator or the DRV8301 as the +3.3V power supply through a shorting cap to realize redundant power supply.

[0007] In the BUCK power supply module of the DRV8301 drive circuit, the switching frequency is adjusted by an external resistor R60, the output voltage is set to 3.3V through voltage-dividing resistors R58 and R59, and voltage stabilization is realized through a freewheeling diode D12 and a filter inductor L2.

[0008] In the three-phase overcurrent protection circuit, the non-inverting input terminal of the LMV331 comparator is connected to the reference voltage divided by resistors R2 and R3. The inverting input terminal receives the sum of the three-phase current sampling signals through adder resistors R7, R10, and R11. The output terminal is connected to the PB12 pin of the ACM32 control system through a filter circuit to trigger the PWM blocking function.

[0009] The MT6826 chip in the magnetic encoder circuit supports the ABZ incremental mode, the UVW commutation mode, and the PWM absolute value output mode, and configures the resolution, zero point, and calibration parameters through the SPI interface.

[0010] The DRV8301 drive circuit configures the current amplifier gain, dead time, and fault protection threshold through the SPI interface, and real-time feedbacks the overcurrent, overheat, and undervoltage fault states to the ACM32 control system.

[0011] In each phase leg of the three-phase inverter circuit, the gate of the upper-arm MOS transistor is connected to the PWM output terminal of the DRV8301 through a current-limiting resistor and a parallel RC circuit, and the gate of the lower-arm MOS transistor is connected through the same structure to improve the stability of the drive signal.

[0012] In the bus voltage detection circuit, after the bus voltage is divided by voltage-dividing resistors R32 and R34, the signal is limited within the range of 0 - 3.3V by the limiting diode D7, and is input to the ACM32 control system through the filter capacitor C28.

[0013] The CAL_EN pin of the MT6826 magnetic encoder chip is connected to the ACM32 control system to achieve the self-calibration function through level triggering, compensating for the magnet mounting deviation and non-linear error.

[0014] The bootstrap capacitors C50, C56, and C57 of the DRV8301 drive circuit are respectively connected to the SH_A, SH_B, and SH_C nodes of the three-phase leg to maintain the drive voltage of the upper-arm MOS transistors.

[0015] The present invention has the following beneficial effects: A torque motor drive control circuit proposed by the present invention uses an ACM32F403CET7 single-chip microcomputer as the main control chip and an integrated drive chip DRV8301 as the MOS transistor drive circuit. This chip also serves as the sampling current amplification circuit and the +3.3V power supply module in the present invention. The chip can also communicate with the ACM32 control system in real time to obtain motor fault status information and perform corresponding configurations. This significantly improves the integration and reliability of the entire system and greatly simplifies the circuit. The present invention uses a magnetic encoder chip to replace the traditional optoelectronic encoder, improving the energy conversion efficiency, reducing the module volume, and enabling precise position detection. The present invention uses a hardware three-phase overcurrent protection module based on an LMV331 comparator, making the protection action of the system faster and more accurate, and enabling the motor to operate more safely and stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the overall block diagram of the hardware circuit implementation of the present invention; Figure 2 is the structural schematic diagram of the ACM32 control system of the present invention.

[0017] Figure 3 is the structural schematic diagram of the A-phase inverter circuit and the current sampling system of the present invention Figure 4 is the structural schematic diagram of the B-phase inverter circuit and the current sampling system of the present invention Figure 5 is the structural schematic diagram of the C-phase inverter circuit and the current sampling system of the present invention Figure 6 is the structural schematic diagram of the MOS transistor drive circuit and the current amplification system of the present invention Figure 7 is the structural schematic diagram of the magnetic encoder system of the present invention Figure 8 is the +3.3V auxiliary power supply circuit and the power supply selection circuit of the present invention Figure 9 is the structural schematic diagram of the DC bus voltage sampling system of the present invention Figure 10 is the structural schematic diagram of the three-phase overcurrent protection system of the present invention DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] Refer to Figure 1 , the present invention includes an auxiliary power supply module, an ACM32 control system, a DRV8301 drive circuit, a three-phase inverter circuit and a current detection circuit, a three-phase overcurrent protection circuit, a bus voltage detection circuit, and a magnetic encoder circuit.

[0020] The auxiliary power supply module includes an external power supply and a +3.3V power supply voltage stabilization circuit. The +3.3V power supply in the present invention can be either the +3.3V generated by the AMS1117 linear voltage regulator or switched to the 3.3V generated by the BUCK circuit carried by the DRV8301. The auxiliary power supply module supplies power to the three-phase inverter circuit, the current detection circuit, the DRV8301 drive circuit, and the ACM32 control system respectively.

[0021] See Figure 2 , the ACM32 control system is used to receive and process the output signals of each part, and output corresponding control signals according to the signals. The ACM32 control system of the present invention uses the ACM32F403CET7 single-chip microcomputer as the control chip. A serial communication interface is reserved in the control module to communicate with the host computer to obtain real-time information.

[0022] A key circuit is provided to control the operating state of the motor, and to realize the start, stop, forward and reverse rotation, and speed control of the torque motor.

[0023] The SPI communication interface communicates with the DRV8301 chip, and the fault state of the torque motor can be obtained. By configuring the registers of the DRV8301, the PWM output mode, overcurrent protection, overvoltage protection, and gain setting of the current amplifier of the system can be set. At the same time, it can also communicate with the MT6826 magnetic encoder to program the output mode change, output resolution adjustment, zero point and other configurations of the chip.

[0024] The PA7, PA8, PA9, PB13, PB14, and PB15 pins of the ACM32F403CET7 are the control signal output pins of the upper and lower bridge arms of the three phases A, B, and C respectively, so as to control the conduction and cut-off of 6 MOS transistors.

[0025] See Figure 3 is the A-phase bridge arm in the three-phase inverter circuit, Figure 4 is the B-phase bridge arm, Figure 5It is the C-phase bridge arm. The ABC three-phase bridge arm structures are exactly the same. Q1 and Q2 are the MOS transistors that constitute the A-phase bridge arm. The drain of Q1 is connected to the positive pole of the external DC power supply. The source of Q1 is connected to the drain of Q2. The source of Q2 is connected in series with the R30 current sampling resistor and then connected to the power ground. The capacitor C22 is used to stabilize the voltage signal obtained by current sampling. GH_A and SH_A are the control signals of the upper bridge arm. GH_A is connected to the gate of the MOS transistor Q1 through a current-limiting resistor to control the turn-on and turn-off of the MOS transistor. The current-limiting resistors R12 and R16 are used to prevent large currents from being generated when charging and discharging the parasitic capacitance of the MOS transistor. The capacitor C6 and the resistor R17 are connected in parallel between GH_A and SH_A to ensure the stability of the drive signal and improve the performance of the MOS transistor. Similarly, GL_A and SL_A are the control signals of the lower bridge arm. GL_A is connected to the gate of the MOS transistor Q2 through a current-limiting resistor to control the turn-on and turn-off of the MOS transistor. The current-limiting resistors R21 and R24 are used to prevent large currents from being generated when charging and discharging the parasitic capacitance of the MOS transistor. The capacitor C18 and the resistor R27 are connected in parallel between GL_A and SL_A to ensure the stability of the drive signal and improve the performance of the MOS transistor.

[0026] See Figure 6 It is a MOS transistor drive circuit that uses the TI's DRV8301 chip. DRV8301 is an integrated three-phase gate drive chip. The chip integrates power MOSFETs, has low on-resistance and efficient switching characteristics, can maximize the reduction of switching losses and conduction losses, and improve the efficiency of motor drive. DRV8301 can monitor the motor current in real time, adjust the current magnitude according to requirements, and at the same time provide functions such as overcurrent protection, overheat protection, and undervoltage lockout to ensure the stability and safety of the motor drive system. The internal of the DRV8301 drive chip includes a MOS transistor drive circuit, a BUCK circuit, and a high-precision differential current amplification circuit. The BUCK circuit can adjust the output voltage and switching frequency to supply power to other parts of the system. DRV8301 has an SPI interface to communicate with the ACM32 control system, providing flexible configuration and monitoring functions, enabling users to set and monitor the status of the motor driver through software.

[0027] In the MOS transistor drive circuit, pins 17, 18, 19, 20, 21, and 22 are the input terminals for the PWM signals controlling the upper and lower bridge arms of the three-phase inverter for phases A, B, and C. Pins 34, 35, 36, 37, 39, 40, 41, 42, 44, 45, 46, and 47 are the output terminals of the PWM signals, which are connected to the corresponding MOS transistor drive interface circuits of the upper and lower bridge arms of the three-phase inverter for phases A, B, and C. C50, C56, and C57 are the bootstrap capacitors for the three phases, with one end connected to pins 48, 43, and 38 of the DRV8301 respectively, and the other end connected to SH_A, SH_B, and SH_C respectively.

[0028] The PWM signals generated by the ACM32 control system are sent to the DRV8301 for processing. Pins 34, 35, 36, 37, 39, 40, 41, 42, 44, 45, 46, and 47 are the output signals for driving the upper and lower bridge arms of phases A, B, and C respectively. Pins 38, 43, and 48 are respectively connected to the half-bridge bootstrap capacitors C57, C56, and C50 of phases A, B, and C. Each half-bridge is configured to drive two N-channel MOSFETs, one for the high side and one for the low side. The half-bridge drivers can be used in combination to drive a three-phase motor or can be used individually to drive various other loads. The peak gate drive current and the internal dead time can be adjusted through corresponding configurations to adapt to various external MOSFETs and applications. The peak gate drive current is set through a register, and the three-phase gate driver can provide an average gate drive current of up to 30 mA. The dead time is adjusted through an external resistor on the DTC pin. By adjusting the resistance of pin 7 of the DRV8301 to the ground, the dead time can be adjusted, with a range of 50 ns to 500 ns, corresponding to directly grounding and grounding through a 150 KΩ resistor respectively. In the present invention, grounding the DTC pin through a 1 Ω resistor will provide a near-minimum dead time (50 ns) and facilitate changing the resistor to adjust the dead time to match different MOS transistors.

[0029] The DRV8301 chip internally integrates a BUCK circuit that can provide voltage for other parts of the system. In the BUCK circuit part, pins 50 and 51 of the DRV8301 are the voltage outputs, which are connected to one end of the inductor L2. The other end of L2 is the output voltage VCC, and C51, C52, and C53 are connected in parallel between VCC and GND to filter the output voltage. D12 is a freewheeling diode, with the positive pole connected to GND and the negative pole connected to VCC. Pin 3 is the feedback voltage pin of the BUCK circuit. After R58 and R59 are connected in series to divide the voltage of VCC, the divided voltage is input to pin 3. The output voltage and the switching frequency can be adjusted, and a current of 1.5 A can be provided externally. By adjusting the resistance of pin 1 to the ground, the switching frequency of the BUCK circuit can be changed. In the invention, R60 is selected as a 205 KΩ resistor. Through calculation using formula (1), the switching frequency can be obtained as 572 KHz.

[0030] (1) Pins 53 and 54 are the input voltage pins of the BUCK circuit, and pins 50 and 51 are the output voltage pins of the BUCK circuit, which are connected to the high-side MOSFET inside the BUCK power supply. Externally, it is connected to the filter inductor L2. L2 is then connected to the filter capacitors C51, C52, and C53. D13 is the freewheeling diode, forming a freewheeling loop. Thus, a complete BUCK circuit is formed. Pin 52 of DRV8301 is the bootstrap capacitor pin of the BUCK circuit, which is connected to the output of the BUCK circuit through a 100 nF capacitor. Pin 3 is the feedback pin of the output voltage. The output voltage is divided by R58 and R59 and then sent to the chip as a feedback signal for closed-loop control. The output voltage of the BUCK circuit is calculated by formula (2) to be 3.3 V. It can supply power to the control system, so a 3.3 V power supply module can be reduced in the auxiliary power supply part.

[0031] (2) DRV8301 includes two high-performance current amplifiers for precise current measurement. It can amplify the sampled three-phase currents. In the current amplification circuit, pins 33, 32, 31, and 30 of DRV8301 are the inputs of the voltages across the sampling resistors of phases A and B. After internal amplification, the outputs are taken at pins 25 and 26, which are connected to R67 and R66 respectively and then output to the ACM32 control system. The current amplifiers of DRV8301 have four programmable gain settings through the SPI register, which are 10, 20, 40, and 80 V / V respectively. The bias is set to half of the voltage on the reference pin (REF). To reduce the DC bias and drift over temperature, DRV8301 provides a calibration method through the DC_CAL pin or the SPI register.

[0032] The sampled current signal of phase A is Figure 3 IA+ and IA- across the sampling resistor R30 in, and similarly, the current signals of phases B and C are IB+ and IB-. These six signals are respectively connected to pins 33, 32, 31, and 30 of DRV8301. These four pins are the input terminals of the current sampling signals. After being processed by the high-performance operational amplifier inside the chip, the obtained current signals are output from pins 25 and 26 of DRV8301. And after RC filtering through R66, R67, C60, and C61, they are sent into the ACM32 control system to adjust the output.

[0033] The DRV8301 has an SPI communication function and can communicate with the ACM32 control system using SPI to set up and monitor the status of the motor driver. The 8th, 9th, 10th, and 11th pins of the chip are respectively the CS, MOSI, MISO, and SCK signals for SPI communication and Figure 2 are connected to the SPI interface of the ACM32 control system. The SPI interface of the chip allows users to read the fault status register to monitor the fault status of the chip. This includes fault information such as overcurrent, overheat, and undervoltage, which helps to quickly diagnose and handle problems. The dead time of the output PWM can also be adjusted through the SPI register to meet different application requirements. The current amplifier has four programmable gain settings, which are 10, 20, 40, and 80 V / V, and are also set through the SPI register. The DC calibration function of the operational amplifier of the chip is calibrated through the DC_CAL pin or the SPI register to reduce DC offset and drift.

[0034] The 4th, 5th, and 6th pins of the DRV8301 correspond to the PWRGD, NOCTW, and NFAULT signals, and the output modes of the three signals are all open-drain outputs. R61, R62, and R63 are the pull-up resistors for the three signals. Then connect to Figure 2 the GPIO interface of the ACM32 control system. If the BUCK output voltage is low due to thermal shutdown, overvoltage, or EN_BUCK shutdown, the PWRGD will output a low-level signal. The NOCTW signal is an overcurrent and overtemperature alarm indication. The NFAULT signal is a fault indication signal.

[0035] See Figure 7 for the magnetic encoder interface circuit. The encoder chip MT6826 used in the present invention is a high-speed and high-precision magnetic angle encoder. It is an angle sensor chip based on advanced AMR magnetic induction technology and advanced signal processing technology, replacing the traditional optical encoder. This chip needs to install a magnet on the motor shaft and face the magnetic encoder chip. It can sense the change in the direction of the magnetic field parallel to the chip surface and output the corresponding angle value. At the same time, the chip has ABZ output mode, UVW output mode, and PWM output mode. The chip has an SPI communication function, and the output mode can be changed and relevant parameters can be adjusted through the SPI communication control register.

[0036] Figure 7 The 9th pin and the 12th pin in

[0037] The incremental ABZ output interface of MT6826 is used in the present invention. Figure 7 The 16th, 15th, and 14th pins of MT6826 are the output signals of A, B, and Z respectively. The chip detects the change of the surface magnetic field to obtain the motor position information, and then converts it into A, B, and Z signals for output. The output signals are connected to GND through resistors R54, R55, and R56, which can ensure the stability of the signals. The signals are output to the ACM32 control system after current limiting through R51, R52, and R53. The ACM32 control system can calculate the real-time position of the motor by calculating the ABZ signals.

[0038] The MT6826 chip has an SPI communication function. The 5th, 6th, 7th, and 8th pins are the MISO, MOSI, SCK, and CS signals of the SPI communication respectively. When using the ABZ mode, any integer resolution of 1 - 1024 pulses / circle can be obtained by rewriting the register through SPI. It can also be changed to the UVW output mode through SPI. MT6826 provides a UVW output that is 120° out of phase with each other to replace the motor commutation control of the traditional three switch Hall elements. The number of pole pairs of UVW per revolution can be programmed and selected between 1 pole pair / revolution - 16 pole pairs / revolution. In addition to providing the incremental ABZ mode and the UVW mode, MT6826 also provides a single-line 12-bit absolute value PWM output mode at the same time. The PWM output is the default output form of pin 10. Zero calibration can also be achieved through SPI communication, including manually calculating the zero point and writing it into the zero point register through SPI instructions or automatically setting the zero point register using SPI.

[0039] The 4th pin of MT6826 is CAL_EN, which is the self-calibration enable control pin. Self-calibration can compensate and calibrate the non-linearity caused by magnet deviation and chip magnet installation deviation. When the system is running at a constant speed and the 4th pin is changed from low level to high level, MT6826 enters the self-calibration state, and the built-in processing circuit of MT6826 will automatically calculate the relevant non-linear parameters and calibrate them, and automatically burn the calibration parameters into the EEPROM to achieve calibration.

[0040] See Figure 8 For the +3.3V auxiliary power supply circuit and power supply selection circuit in the present invention, U1 is an AMS1117 linear voltage regulator, and the 3rd pin is its input voltage pin. The +5V voltage of the USB is connected to the 3rd pin of U1 after filtering through C1 and C2 as the input of the linear voltage regulator. The 1st pin of U1 is connected to GND. The 3rd pin of U1 is its +3.3V voltage output pin, and C3 and C4 are connected in parallel between the output voltage and GND to stabilize and filter the output. LED1 is for signal indication, and R1 is the current limiting resistor of LED1. When the circuit works normally, LED1 will light up.

[0041] H1 is a 1*3P pin header. The 1st pin is connected to the +3.3V voltage output by U1. The 2nd pin is connected to other parts that require +3.3V power supply. The 3rd pin is connected to the +3.3V output of the BUCK circuit part of DRV8301 in Figure 6 When the 1st pin is connected to the 2nd pin or the 3rd pin is connected to the 2nd pin through a shorting cap, the power supply mode of the +3.3V power supply can be selected. When one of the +3.3V power supplies fails, the power supply mode can still be switched to enable the system to continue operating normally, improving the reliability and stability of the entire system.

[0042] See Figure 9 for the DC bus voltage detection circuit in the present invention. C24, C25, and C26 are connected in parallel between PVDD and PGND to form filter capacitors. R32 and R34 form a series voltage-dividing resistor. Then, the voltage signal across R34 is regulated and filtered by C28 to obtain the output voltage signal. D7 is a switching diode, whose function is to limit the output signal. When the voltage is higher than 3.3V, the left diode conducts, and due to the diode clamping, the voltage is limited to 3.3V. When the voltage is lower than 0V, the right diode conducts, and due to the diode clamping, the voltage is limited to 0V. The output voltage signal is limited between 0 - 3.3V, thus protecting the pins of the ACM32 control system.

[0043] See Figure 10 for the three-phase overcurrent protection circuit in the present invention. The three current sampling signals IA+, IB+, and IC+ are connected together through resistors R7, R10, and R11 to form an adder. The added signal is sent through resistor R8 to the inverting input terminal of the comparator LMV331. Capacitor C65 is connected in parallel between the input signal and AGND to make the added current signal more stable. R2 and R3 are connected in series between +3.3V and AGND to form a voltage-dividing resistor. The function of capacitor C5 is to regulate and filter the power supply to make the voltage division more stable. The voltage divided by R3 is sent through resistor R5 to the non-inverting input terminal of the comparator, forming a hardware voltage comparison circuit. The 4th pin of comparator U2 is the output port. When the voltage value at the inverting input terminal is lower than the voltage value at the non-inverting input terminal, the motor runs normally and the output terminal is at a high level. When the voltage value at the inverting input terminal is higher than the voltage value at the non-inverting input terminal, the motor runs with a fault and the output terminal is at a low level. The output terminal is connected to +3.3V through the light-emitting diode LED2 and the current-limiting resistor R4 to form a fault indication circuit. When there is a fault, the comparator outputs a low level, and LED2 conducts and emits light. At the same time, the output of the comparator is also connected to the ACM32 control system or other parts for subsequent fault protection actions.

[0044] When the motor is running normally, the three phases are balanced and the sum of the three-phase currents is always zero. When a fault occurs in one of the phases, such as a short circuit, the current value of the short-circuited phase is much higher than that of the other two phases. At this time, the three phases are unbalanced and the sum of the three-phase currents is not zero. Assume that the single-phase current is 1A during normal operation, and the current of the short-circuited phase is 30A during single-phase short circuit. Assume that when a single-phase short circuit occurs in phase A, the sampled current signal of phase A is calculated to be 0.3V, and the current signals of phases B and C are both 0.01V. At this time, since the amplitude of the input voltage signal of phase A is much larger than that of phases B and C, the voltage division of phases B and C can be ignored, and the signals of phases B and C are short-circuited. Figure 10 R10 and R11 in Figure 10 are connected in parallel and then in series with R7. The signal input to the inverting terminal of the comparator is the voltage across the parallel connection of R10 and R11. The voltage value calculated by formula (3) is 0.1V.

[0045] (3) Then, according to the fact that the amplitude of the input voltage at the inverting terminal during the fault is approximately 0.1V, it can be determined that the amplitude of the voltage at the non-inverting terminal is also 0.1V. According to formula (4), R3 is calculated to be about 620Ω.

[0046] (4) The hardware three-phase current protection circuit composed of a comparator used in the present invention can effectively prevent the motor equipment from being damaged due to overcurrent and extend the service life of the equipment. Compared with software overcurrent protection, hardware overcurrent protection has a faster response speed and can perform protection actions more quickly when a motor fault occurs. Moreover, hardware overcurrent protection has higher reliability and will not cause the protection device to fail to act or act untimely due to the operation problems of the ACM32 control system.

Claims

1. A torque motor drive control circuit, characterized in that It includes an auxiliary power supply module, an ACM32 control system, a DRV8301 drive circuit, a three-phase inverter circuit, a current detection circuit, a three-phase overcurrent protection circuit, a bus voltage detection circuit, and a magnetic encoder circuit; The auxiliary power supply module includes an external power supply and a +3.3V power supply voltage stabilization circuit. The +3.3V power supply voltage stabilization circuit generates a +3.3V power supply through an AMS1117 linear voltage regulator or the BUCK circuit in the DRV8301 drive circuit, and realizes power supply switching through a power supply selection circuit; The ACM32 control system is based on the ACM32F403CET7 single-chip microcomputer and communicates with the DRV8301 drive circuit and the magnetic encoder circuit through the SPI interface, and is used to receive sensor signals, output PWM control signals, and configure drive parameters; The DRV8301 drive circuit integrates a MOS tube drive module, a BUCK power supply module, and a high-precision differential current amplification module. The MOS tube drive module of it connects the upper and lower bridge arm MOS tubes of the three-phase inverter circuit through a bootstrap capacitor. The BUCK power supply module outputs +3.3V voltage through an inductor L2 and a filter capacitor. The current amplification module amplifies the three-phase current sampling signal and inputs it to the ACM32 control system; The three-phase inverter circuit and the current detection circuit include A-phase, B-phase, and C-phase bridge arms. Each phase bridge arm consists of upper and lower bridge arm MOS tubes and a series-connected sampling resistor. The voltage across the sampling resistor is processed by the DRV8301 current amplification module and fed back to the ACM32 control system; The magnetic encoder circuit uses an MT6826 magnetic encoder chip and is connected to the ACM32 control system through the SPI interface, and outputs ABZ signals to realize motor position detection; The three-phase overcurrent protection circuit is based on an LMV331 comparator. It sums the three-phase current sampling signals through an adder and compares them with a reference voltage, outputs an overcurrent fault signal to the ACM32 control system, and drives a fault indicator at the same time; The bus voltage detection circuit converts the bus voltage into a signal in the range of 0 - 3.3V through a voltage-dividing resistor and a limiting diode, and inputs it to the ACM32 control system.

2. The torque motor drive control circuit according to claim 1, wherein The power supply selection circuit includes a 1×3P header pin. The AMS1117 linear voltage regulator or the BUCK circuit of the DRV8301 is selected as the +3.3V power supply through a shorting cap to realize redundant power supply.

3. The torque motor drive control circuit according to claim 1, wherein, In the BUCK power supply module of the DRV8301 drive circuit, the switching frequency is adjusted by an external resistor R60, the output voltage is set to 3.3V through voltage-dividing resistors R58 and R59, and voltage stabilization is realized through a freewheeling diode D12 and a filter inductor L2.

4. The torque motor drive control circuit according to claim 1, wherein, In the three-phase overcurrent protection circuit, the positive input terminal of the LMV331 comparator is connected to the reference voltage divided by resistors R2 and R3. The negative input terminal receives the sum of the three-phase current sampling signals through adder resistors R7, R10, and R11. The output terminal is connected to the PB12 pin of the ACM32 control system through a filter circuit to trigger the PWM blocking function.

5. The torque motor drive control circuit according to claim 1, wherein The MT6826 chip in the magnetic encoder circuit supports the ABZ incremental mode, the UVW commutation mode, and the PWM absolute value output mode, and configures the resolution, zero point, and calibration parameters through the SPI interface.

6. The torque motor drive control circuit according to claim 1, characterized in that, The DRV8301 drive circuit configures the current amplifier gain, dead time, and fault protection threshold through the SPI interface, and real-time feeds back the overcurrent, overheat, and undervoltage fault states to the ACM32 control system.

7. The torque motor drive control circuit according to claim 1, wherein In each phase leg of the three-phase inverter circuit, the gate of the upper-arm MOS transistor is connected to the PWM output terminal of the DRV8301 through a current-limiting resistor and a parallel RC circuit, and the gate of the lower-arm MOS transistor is connected through the same structure to improve the stability of the drive signal.

8. The torque motor drive control circuit according to claim 1, wherein, In the bus voltage detection circuit, the voltage-dividing resistors R32 and R34 divide the bus voltage, and then limit the signal within the range of 0 - 3.3V through the limiting diode D7, and input it to the ACM32 control system through the filtering capacitor C28.

9. The torque motor drive control circuit according to claim 1, wherein The CAL_EN pin of the MT6826 magnetic encoder chip is connected to the ACM32 control system, and the self-calibration function is realized through level triggering to compensate for the magnet mounting deviation and non-linear error.

10. The torque motor drive control circuit according to claim 1, characterized in that, The bootstrap capacitors C50, C56, and C57 of the DRV8301 drive circuit are respectively connected to the SH_A, SH_B, and SH_C nodes of the three-phase bridge arm to maintain the drive voltage of the upper-arm MOS transistor.

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