Driving control and over-current protection circuit of permanent magnet synchronous motor

Abstract

The invention discloses a permanent magnet synchronous motor drive control and overcurrent protection circuit. The circuit comprises an auxiliary power supply module, a three-phase current sampling circuit, a three-phase inverter circuit, an ACM32 microcontroller module, an RS422 communication interface module, a drive circuit module and an overcurrent protection circuit module. The auxiliary power supply module provides stable power supply for each module through a multi-stage voltage stabilization design; the three-phase current sampling circuit adopts a single-point grounding and operational amplifier amplification technology to accurately collect three-phase current signals; the overcurrent protection circuit triggers LED indication and microcontroller protection action through low-pass filtering and voltage comparison, and abnormal current is cut off in real time. The system has the advantages of being autonomous and controllable, high in integration level, rapid in response and high in reliability.

Description

Technical Field

[0001] The present invention belongs to the technical field of permanent magnet synchronous motors, and relates to a driving control and overcurrent protection circuit for a permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motors have developed rapidly due to their simple structure, high power density, high energy consumption efficiency, good robust performance, strong stability and anti-interference ability. At the same time, due to the extensive use of rare earth materials in the research of permanent magnets in recent years, the efficiency of the permanent magnets used in permanent magnet synchronous motors has been significantly improved. After magnetization, the permanent magnets can form a constant magnetic field, with good excitation characteristics, and the permanent magnets are lighter in mass, stronger in stability and lower in loss than electric excitation. In recent years, the development of power electronics technology has made the control of permanent magnet synchronous motors more precise and flexible.

[0003] Vector control and direct torque control are two main control methods for permanent magnet synchronous motors. Vector control decomposes the stator current into mutually perpendicular magnetizing current components and torque current components through coordinate transformation to achieve decoupled control of the magnetic field and torque, and equivalent the control of AC motors to that of DC motors. The main idea of direct torque control is to regard the inverter and the motor as a whole, without the need for coordinate transformation, and the system torque response speed is fast. However, due to the use of discrete hysteresis control in direct torque control, there is a problem of torque ripple. The implementation of the vector control theory and direct torque control theory of permanent magnet synchronous motors depends on the motor drive system, and their control performance is affected by the rotational speed, current, voltage measurement feedback accuracy of the motor drive system and the control accuracy of the power inverter. Therefore, a good motor drive system is the guarantee for the high performance and high reliability of the permanent magnet synchronous motor speed regulation system. However, the core controllers of existing permanent magnet synchronous motor drive systems mostly use foreign chips. In addition, the MOS tubes of traditional permanent magnet synchronous motor drive systems often use 6 or 3 discrete opto-isolation cores for driving, resulting in large equipment volume, high cost and poor economics. Therefore, a permanent magnet synchronous motor drive system with the characteristics of simplicity, high efficiency and high reliability has important research value. Summary of the Invention

[0004] The purpose of the present invention is to provide a driving control and overcurrent protection circuit for a permanent magnet synchronous motor, which solves the problems existing in the prior art.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows: A permanent magnet synchronous motor drive control and overcurrent protection circuit, comprising: an auxiliary power supply module, a three-phase current sampling circuit, a three-phase inverter circuit, an ACM32 microcontroller module, an RS_422 communication interface module, a drive circuit module, and an overcurrent protection circuit module; the auxiliary power supply module supplies power to the three-phase inverter circuit, the ACM32 microcontroller module, the RS_422 communication interface module, the drive circuit module, and the overcurrent protection circuit module; the three-phase inverter circuit, the ACM32 microcontroller module, the RS_422 communication interface module, the magnetic encoder interface circuit, the drive circuit module, and the overcurrent protection circuit module are interconnected; both ends of the drive circuit module are respectively connected to the ACM32 microcontroller module and the three-phase inverter circuit; the overcurrent protection circuit module detects three-phase current signals in real time through the three-phase current sampling circuit, and triggers a protection action according to the detection result.

[0006] The auxiliary power supply module includes: a +15V power supply unit, a +5V power supply unit, a +3.3V power supply unit, and a +1.65V reference voltage unit; among them, the +15V power supply unit uses a switching power supply chip TPS5430DDA to achieve voltage conversion, and adjusts the output voltage through an inductor L1 and voltage-dividing resistors R1 and R2; the +5V power supply unit performs voltage conversion through a chip RY8310; the +3.3V power supply unit is stepped down and output by a linear voltage regulator AMS1117, and the power supply status is indicated by an LED3; the +1.65V reference voltage unit is generated by an operational amplifier U19.1 and a resistor voltage-dividing circuit, and the output is stabilized through a filter capacitor.

[0007] The three-phase current sampling circuit includes three single-phase current sampling units with the same structure, and each unit includes: sampling resistors (R23, R26, R27), operational amplifiers (LTC358), coupling capacitors (C26, C31, C32), current-limiting resistors (R25, R28, R29), and bypass capacitors (C33, C34, C35); the operational amplifier amplifies the voltage signal across the sampling resistor through a negative feedback circuit, and eliminates ground loop interference through single-point grounding (AGND).

[0008] The three-phase inverter circuit uses six power switch tubes (Q1-Q6, model STB60NF06LT4) to form a three-phase bridge arm, and a 10mΩ resistor (R54, R55, R56) is connected in series to the source of the lower transistor of each bridge arm to detect the phase current; a PGND (power ground) is set in the three-phase inverter circuit to reduce ground wire noise, and a gate drive protection circuit is used to suppress voltage spikes.

[0009] The ACM32 microcontroller module is connected to the magnetic encoder interface circuit through the SPI bus and receives the position signal output by the magnetic encoder (MT6826S-QFN-24); the microcontroller module exchanges data with the RS_422 communication interface module through the UART2_TX and UART2_RX pins, and outputs a control signal to the drive circuit module through the GPIO pins.

[0010] The drive circuit module uses the drive chip FD6288T. Its input terminals (HIN1-HIN3, LIN1-LIN3) receive the PWM signal of the microcontroller, and the output terminals (HO1-HO3, LO1-LO3) are connected to the three-phase inverter circuit; the drive circuit module realizes the boost of the drive voltage of the upper-bridge power tube through the bootstrap capacitor (C68) and diodes (U15, U17, U18).

[0011] The overcurrent protection circuit module includes: a low-pass filter (R7, R10, C12), an operational amplifier (LMV331), a reference voltage comparison unit, and an LED indication circuit (LED2, R19); the operational amplifier compares the three-phase current signal with the reference voltage, and when the output is high, it triggers the LED2 to light up and sends a protection signal to the microcontroller module to cut off the drive signal.

[0012] The input power supply of the +15V power supply unit forms a freewheeling loop through the inductor L1 and the diode D1, and eliminates the ripple noise through multiple filter capacitors (C1-C8).

[0013] The gain of the single-phase current sampling unit is determined by the ratio of the feedback resistor R33 to the sampling resistor R23, and the gain calculation formula is: .

[0014] The cut-off frequency of the low-pass filter is set by the values of the resistors (R7, R10) and the capacitor (C12), and is used to filter out high-frequency noise and smooth the input signal.

[0015] The object of the present invention is to implement effective overcurrent protection for a permanent magnet synchronous motor. During the operation of the permanent magnet synchronous motor, overcurrent phenomena may occur due to various reasons, such as sudden load changes, short-circuit faults, etc. This will not only cause damage to itself, such as burning out windings, damaging insulation, etc., but also have an adverse impact on the equipment connected thereto and the entire power system, and may even lead to safety accidents. The permanent magnet synchronous motor drive control and overcurrent protection circuit provided by the present invention can complete the overcurrent protection of the permanent magnet synchronous motor by using the overcurrent protection circuit. When the motor has an overcurrent situation, it can timely and accurately detect the abnormal current and quickly take corresponding protection measures, thereby effectively avoiding damage to the motor caused by overcurrent, ensuring the reliable operation of the permanent magnet synchronous motor, extending its service life, and at the same time ensuring the safety and stability of related equipment and the power system, and improving the operation efficiency and reliability of the entire system. Description of the Drawings

[0016] Figure 1 is the system structure block diagram of the present invention; Figure 2 is the schematic diagram of the +15V power supply structure of the present invention; Figure 3 is the schematic diagram of the +5V power supply structure of the present invention; Figure 4 is the schematic diagram of the +3.3V power supply structure of the present invention; Figure 5 is the schematic diagram of the +1.65V reference voltage structure of the present invention; Figure 6 is the schematic diagram of the three-phase current sampling circuit structure taking phase A as an example of the present invention; Figure 7 is the schematic diagram of the three-phase inverter circuit structure taking phase A as an example of the present invention; Figure 8 is the schematic diagram of the MUC control module circuit structure of the present invention; Figure 9 is the schematic diagram of the RS_422 communication interface circuit of the present invention; Figure 10 is the schematic diagram of the magnetic encoder interface circuit of the present invention; Figure 11 is the schematic diagram of the drive circuit structure of the present invention; Figure 12 is the schematic diagram of the overcurrent protection circuit structure of the present invention.

[0017] Figure 1Among them, (1) is the auxiliary power supply, (2) is the ACM32 MUC control module, (3) is the FD6288 drive circuit, (4) is the three-phase inverter, (5) is the three-phase current sampling, (6) is the overcurrent protection, (7) is the RS_422 communication interface, (8) is the MT6826 magnetic encoder, and (9) is the permanent magnet synchronous motor. Specific implementation manners

[0018] The present invention will be described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0019] A permanent magnet synchronous motor drive control and overcurrent protection circuit includes an auxiliary power supply, a three-phase inverter circuit, an ACM32 microcontroller, an RS_422 communication interface, a drive circuit, and an overcurrent protection circuit; the auxiliary power supply supplies power to the three-phase inverter circuit, the ACM32 microcontroller, the RS_422 communication interface, the drive circuit, and the overcurrent protection circuit; the three-phase inverter circuit, the ACM32 microcontroller, the RS_422 communication interface, the magnetic encoder interface circuit, the drive circuit, and the overcurrent protection circuit are connected; both ends of the drive circuit are respectively connected to the ACM32 microcontroller and the three-phase inverter circuit.

[0020] The auxiliary power supply includes a +15V power supply, a +5V power supply, a +3.3V power supply, and a +1.65V reference voltage, which provides stable power supply voltages for different circuit modules of the entire system to ensure that each part of the circuit can work properly. The +15V power supply part is mainly composed of components such as inductor L1, diode D1, capacitors C1, C2 - C8, resistors R1 - R6, and chip TPS5430DDA. After the input power supply (PU_24V) passes through inductor L1, it is connected to the input terminal of chip TPS5430DDA. Chip TPS5430DDA is a switching power supply chip that integrates components such as power MOSFETs inside and can achieve efficient voltage conversion. Resistors R1 and R2 form a voltage division circuit and are connected to the feedback pin (FB) of the chip to detect the output voltage and feedback it to the chip to achieve stable regulation of the output voltage. When the output voltage increases, the voltage after voltage division also increases. The chip adjusts the internal switching frequency or duty cycle according to the feedback signal, thereby reducing the output voltage and maintaining it at around +15V. Diode D1 plays a freewheeling role during the operation of the switching power supply. When the switching transistor inside the chip is turned off, the current in inductor L1 cannot change suddenly and will form a loop through diode D1 to continue supplying power to the load, and at the same time release the energy stored in the inductor to maintain the stability of the output voltage. Capacitors C2 - C8 are used for filtering to filter out high-frequency noise and ripple in the output voltage, making the output +15V power supply smoother and more stable. Capacitor C1 plays an input filtering role to filter out the noise in the input power supply and ensure the normal operation of the chip. The +5V power supply part includes components such as inductor L2, capacitors C9 - C11, C13 - 14, resistors R8, R12, and chip RY8310. Voltage conversion is achieved through chip RY8310. The input power supply enters the chip after passing through inductor L2. Resistors R8 and R12 form a voltage division circuit and are connected to the feedback pin of the chip to detect and regulate the output voltage to make it stable at +5V. Inductor L2 stores and releases energy during the switching process. Capacitors C11 - C19 are used for filtering to filter out the ripple and noise of the output voltage and provide a clean +5V power supply. The +3.3V power supply part mainly has components such as chip AMS1117, capacitors C19 - C22, resistor R20, and LED3. Chip AMS1117 is a linear voltage regulator that steps down the input voltage to +3.3V output. Capacitors C19 - C22 are used for filtering. Input capacitors C19 and C20 can filter out high-frequency noise in the input voltage, and output capacitors C21 and C22 can make the output +3.3V voltage more stable and reduce ripple. Resistor R20 and LED3 form a simple indication circuit. When the +3.3V power supply works normally, LED3 lights up to indicate the power supply status. The +1.65V reference voltage part includes components such as operational amplifier U19.1 (LTC358), resistors R9, R11, and capacitors C15 - C17, and uses the operational amplifier and resistor voltage division to generate a +1.65V reference voltage, +3.The 3V power supply is divided by resistors R9 and R13, and the divided voltage is input to the non-inverting input terminal of operational amplifier U19.1. The operational amplifier has the characteristics of high input impedance and low output impedance, playing a role of buffering and isolation, making the output +1.65V reference voltage more stable and not affected by the load change of the subsequent circuit. Capacitors C15 - C17 are used for filtering to further improve the stability and accuracy of the reference voltage.

[0021] The three-phase current sampling circuit is composed of three single-phase current sampling circuits with the same structure, corresponding to the sampling of three-phase currents (IA, IB, IC) respectively; two power supply voltages of +1.65V and +3.3V are used in the circuit. The +1.65V power supply is filtered by filter capacitors (such as C23, C24, C25) and supplies power to some pins of the operational amplifier. The +3.3V power supply supplies power to other pins of the operational amplifier and some resistors. The whole circuit adopts single-point grounding (AGND), connecting all the component pins that need to be grounded to the same ground node to avoid the noise and interference caused by ground loops and ensure the signal integrity of the circuit; each single-phase circuit contains components such as operational amplifiers (LTC358), resistors (R21, R23, etc.), capacitors (C23, C26, etc.) for converting three-phase current signals into measurable voltage signals for subsequent signal processing and monitoring; sampling resistors (such as R23, R26, R27) are connected in series in the current input loop. The value of the sampling resistor is small (1.2KΩ / 1%) to reduce the influence on the original circuit current and at the same time ensure that a large enough voltage signal can be generated for subsequent circuit processing; feedback resistors (such as R25, R27, R26) and the operational amplifier form a negative feedback circuit for setting the gain of the operational amplifier. Taking the first single-phase circuit as an example, R33 (20kΩ) and R23 (1.2KΩ) jointly determine the gain of this circuit, and the gain value is: Current-limiting resistors (such as R25, R28, R29) with a resistance value of 68 Ω mainly play a role in current limiting to protect the input terminal of the operational amplifier and prevent excessive current from damaging the operational amplifier; Filter capacitors (such as C23, C24, C25) with a capacitance value of 10 nF are connected between the power supply pin (+1.65 V) and the ground (AGND) to filter out high-frequency noise on the power supply, enabling the operational amplifier to work stably and avoiding the influence of power supply noise on the circuit performance; Coupling capacitors (such as C26, C31, C32): with a capacitance value of 68 pF, are connected between the current input signals (IA+, IB+, IC+) and the input terminal of the operational amplifier, playing a role of blocking direct current and passing alternating current, allowing only alternating current signals to pass through while blocking the direct current component to ensure that the alternating current change part of the current is sampled; Bypass capacitors (such as C33, C34, C35): with a capacitance value of 100 pF, are connected between the output terminal of the operational amplifier and the ground to filter out high-frequency noise in the output signal and make the output signal smoother; The operational amplifier (LTC358) is used to amplify the voltage signal on the sampling resistor, featuring high input impedance, low offset voltage, etc., capable of accurately amplifying weak current signals and converting them into voltage signals for output; For the IA phase, after the current signal is converted into a voltage signal through the sampling resistor R23, it is input to the non-inverting input terminal (pin 3) of the operational amplifier and output from the output terminal (pin 1) after amplification; Taking the IA-phase current sampling as an example, the current IA flows in from IA+, passes through the sampling resistor R23, and a voltage drop proportional to IA is generated across R23. This voltage signal is input to the non-inverting input terminal (pin 3) of the operational amplifier U20.1 through the coupling capacitor C26. At the same time, the inverting input terminal (pin 2) of the operational amplifier is grounded through the resistor R30 and connected to the output terminal (pin 1) through the feedback resistor R33 to form a negative feedback amplifier circuit. According to the virtual short and virtual open characteristics of the operational amplifier, the relationship between the output voltage IU and the input current IA is: The amplified voltage signal IU is output through the current-limiting resistor R18. At the same time, the output terminal is grounded through the bypass capacitor C33 to filter out high-frequency noise; The current sampling processes of the IB phase and the IC phase are similar to that of the IA phase.

[0022] Six power switch transistors Q1 - Q6 with the model number STB60NF06LT4 are used in the three - phase inverter circuit. These are the core components of the circuit and are used to achieve the DC - to - AC inversion process. Each switch transistor has a corresponding drive circuit. Taking phase A as an example, GH_A is connected to the gate of Q2 through a 10Ω resistor R37, SH_A is connected to the source of Q2, GL_A is connected to the gate of Q2 through a 10Ω resistor R46, and SL_A is connected to the source of Q2. The B - phase and C - phase have the same structure. The resistors play a current - limiting role to prevent excessive current from damaging the gates of the switch transistors. Diodes (such as D4, D7, etc.) and capacitors (such as C36, C48, etc.) in the gate circuit form a gate drive protection circuit, which is used to suppress the spikes and oscillations of the gate voltage and protect the gates of the switch transistors. By controlling the conduction and cutoff sequence and time of the six power switch transistors, the DC power supply is converted into a three - phase AC output. Within one cycle, the upper and lower two switch transistors of each bridge arm (Q2 and Q5 form the phase - A bridge arm, Q1 and Q4 form the phase - B bridge arm, Q3 and Q6 form the phase - C bridge arm) alternately conduct and cutoff. By continuously switching the conduction and cutoff states of the switch transistors according to a certain rule, a three - phase AC voltage can be obtained on the load. Multiple capacitors (C39, C40, C41, etc.) in the circuit play a filtering role, filtering out the ripples in the DC power supply to make the DC voltage smoother. At the same time, they absorb the high - frequency noise and voltage spikes generated during the inversion process to protect the circuit components. A 10mΩ resistor (R54, R55, R56) is connected in series to the source of the lower transistor of each bridge arm for detecting the phase current and functions such as current closed - loop control and over - current protection. PGND (power ground) in the circuit provides a low - impedance grounding path for the power circuit, reducing the noise and interference on the ground wire.

[0023] The circuit in the ACM32 microcontroller uses a +3.3V power supply to power the MCU control module. Capacitors C58 (100nF) and C59 (100nF) are connected in parallel near the power supply pins to filter the power supply, filtering out high-frequency noise in the power supply to ensure the stability of the power supply voltage and provide the working voltage. Capacitor C56 (100nF) is connected between the +3.3V power supply and ground to reduce the impact of power supply fluctuations on the circuit. The reset pin NRST (pin 7) is connected to the +3.3V power supply through resistor R64 (1kΩ) and grounded through capacitor C60 (0.1μF). When the system is powered on, capacitor C60 charges and the voltage of the NRST pin gradually rises. During the charging process of the capacitor, the NRST pin remains low for a period of time to achieve the power-on reset function of the MCU control module. Switch SW1 can manually trigger a reset. When pressed, it pulls the NRST pin low to reset the MCU control module. The MCU control module is connected to an external crystal oscillator through pins PF0-OSC_IN (pin 5) and PF1-OSC_OUT (pin 6) to provide an accurate clock signal for the chip. UART2_TX (pin 13) and UART2_RX (pin 14) are used to implement serial communication for data exchange with external devices. By configuring parameters such as the baud rate, data bits, and stop bits of the serial port, data communication at different rates and formats can be achieved. RE_RS422 (pin 38) and DE_RS422 (pin 20) are enable pins for RS_422 communication to implement the RS_422 communication function. SPI2_MISO (pin 42), SPI2_MOSI (pin 43), SPI2_SCK (pin 44), and SPI2_CS (pin 46) form an SPI bus interface. Through the SPI interface, the MCU control module can read or write data from external devices to achieve control and data interaction with external devices. The MCU control module has multiple GPIO pins for connecting external devices and sensors. Pins such as UH (pin 29), VH (pin 30), and WH (pin 31) are used to output control signals to control the working state of the external circuit to achieve functions such as switching control and speed regulation of external devices. Pins such as Z+ / HALL_3 (pin 39), A+ / HALL_1 (pin 40), and B+ / HALL_2 (pin 41) are used to connect magnetic encoders to detect the position and speed information of the motor, convert the rotational position and speed of the motor into electrical signals, and input them into the MUC control module. After the processing circuit inside the MCU control module processes the electrical signals, closed-loop control of the motor is achieved to ensure the precise operation of the motor. SPI interface pins such as SPI2_CS (pin 46), SPI2_MISO (pin 42), SPI2_MOSI (pin 43), and SPI2_SCK (pin 44) are used to connect to an external Flash memory to store information such as program code and data. Inductor L3 (220Ω) and capacitor C61 (4.A filter circuit is composed of C61 (7 μF) and C62 (4.7 μF) to ensure a more stable power supply for the MCU control module and reduce the impact of power supply noise on the internal circuit of the MCU.

[0024] In the RS_422 communication interface circuit, the +3.3V power supply is used to power the RS_422 communication chip U11 (ADM3491ARZ-1). The capacitor C55 (0.1 μF) is connected between the power supply pin and the ground to filter out high-frequency noise in the power supply and ensure that the chip obtains a stable power supply voltage. TX RS422 (pin 5) is the input terminal for the TTL-level transmission signal from the microcontroller. When a high level or low level is input to this pin, the internal circuit of the chip converts it into a differential signal that conforms to the RS_422 standard and outputs it from the corresponding output pins. TX_H (pin 1) and TX_L (pin 4) are the output terminals of the differential transmission signal after conversion by the chip. The diode D13 (BAT54A, 215) is connected between TX_H and TX_L and the ground to play a protective role and prevent excessive voltage spikes on the output signal line from damaging the chip. RX RS422 (pin 12) is the output terminal after the chip converts the received differential signal into a TTL level for subsequent microcontroller reading. RX_H (pin 2) and RX_L (pin 3) are the differential reception signal input terminals for receiving external RS_422 differential signals. The diode D10 (BAT54A, 215) plays a protective role to prevent overvoltage on the reception signal line from damaging the chip. The resistors R61 (1.5 kΩ) and R63 (1.5 kΩ) are connected between TX_H and TX_L and between RX_H and RX_L to provide a suitable bias voltage for the differential signal and ensure that the differential signal is in a stable intermediate level state when there is no signal transmission, facilitating the receiving end to accurately identify the high and low level changes of the signal. RX LED (D11) is connected to the +3.3V power supply through the resistor R65 (3.3 kΩ). When the chip receives a valid RS_422 signal, the RX RS422 pin outputs the corresponding level to turn on the RX LED, which is used to indicate the status of received data. TX LED (D12): is connected to the +3.3V power supply through the resistor R66 (3.3 kΩ). When a valid TTL-level signal is input to the TX RS422 pin, the TX LED is turned on, which is used to indicate the status of transmitted data. The connector H1 (PZ254V-11-04P) is used to connect the external RS_422 communication cable to connect the differential transmission and reception signals of the chip to external devices and achieve the physical connection of RS_422 communication. The test terminal H2 (PZ254V-11-06P): provides a convenient test point for measuring and monitoring the status of RS_422 communication signals during debugging and testing, which helps to quickly locate and solve communication problems.

[0025] In the magnetic encoder interface circuit, the circuit uses a +5V power supply to power the magnetic encoder chip MT6826S-QFN-24. The capacitor C67 (100nF) is connected between the power supply pin (VDD, pin 11) and the ground (VSS, pin 14) to filter out high-frequency noise in the power supply, ensuring that the chip obtains a stable power supply voltage to guarantee its normal operation. The chip communicates with the MUC microcontroller through the SPI bus, including the CSN (pin 7, chip select signal), MISO (pin 5, master input slave output), MOSI (pin 4, master output slave input), and SCK (pin 6, serial clock) pins. When the CSN pin is at a low level, the chip is selected, allowing the external controller to communicate with the chip via SPI. When the pin is at a high level, the chip is in an unselected state and does not respond to SPI communication. MISO and MOSI are used for data transmission. The external controller sends instructions and data to the chip through the MOSI pin, and the chip sends data to the external controller through the MISO pin. The SCK is provided with a clock signal by the external controller to synchronize the data transmission of SPI communication, ensuring that data is read and written at the correct moment. The A (pin 18), B (pin 17), and Z (pin 16) pins of the chip output the position signals of the magnetic encoder, which are connected to the A+ / HALL_1, B+ / HALL_2, and Z+ / HALL_3 lines through resistors R75 (120Ω), R76 (120Ω), and R77 (120Ω) respectively. Usually, they are pulse signals used to reflect the rotation position and speed information of the magnetic encoder. The two signals A+ / HALL_1 and B+ / HALL_2 have a 90-degree phase difference. By detecting the pulse changes, the rotation direction and angular position of the magnetic encoder are determined. By counting the pulses, the rotation angle and speed of the magnetic encoder are calculated. The Z+ / HALL_3 is an index pulse signal that outputs one pulse per revolution, providing an absolute position reference point to help the system for initialization and calibration. Resistors R78 (10kΩ), R79 (10kΩ), and R80 (10kΩ) are respectively connected between the MT_A, MT_B, and MT_Z signal lines and the ground, acting as pull-down resistors to ensure that the signal lines are in a stable low-level state when there is no signal output, preventing false triggering or interference caused by the floating state on the signal lines.

[0026] In the driving circuit, the circuit uses a +15V power supply to power the driving chip U16 (FD6288T). The power supply is connected through the diode U15 (SS34A). The diode plays a role in preventing the reverse connection of the power supply and protecting the circuit components. The capacitor C68 (22uF) is connected between the power supply pin and the ground, playing a filtering role to filter out the high-frequency noise in the power supply, making the power supply more stable and ensuring the normal operation of the driving chip; HIN1-HIN3 (pins 1, 2, 3) and LIN1-LIN3 (pins 4, 5, 6) are input control signal pins, which are used to control the conduction and cutoff of the upper and lower transistors of the three-phase bridge arm respectively. When HIN1 controls the conduction of the upper bridge arm of phase A, LIN1 controls the conduction of the lower bridge arm of phase A; the microcontroller inputs PWM (pulse width modulation) signals or high and low level signals through the pins to control the speed and direction of the motor; VCC (pin 7): the power supply pin of the chip, connected to the +15V power supply to power the internal circuit of the chip; HO1-HO3 (pins 19, 15, 12) and LO1-LO3 (pins 11, 10, 9) are the output pins of the driving chip, which are respectively connected to the three-phase windings of the three-phase motor; VB1-VB3 (pins 20, 16, 13) and VS1-VS3 (pins 17, 14, 13) form a bootstrap circuit, which is used to drive the upper bridge arm power transistor; capacitors C68 (22uF), etc. are connected between the VB and VS pins, playing the role of bootstrap capacitors; when the lower bridge arm inside the chip conducts, the bootstrap capacitor is charged through the lower bridge arm; when the upper bridge arm needs to conduct, the bootstrap capacitor provides a driving voltage higher than the power supply voltage for the upper bridge arm, enabling the upper bridge arm to conduct reliably; the diodes U15 (SS34A), U17 (SS34A), U18 (SS34A) are used to prevent the current from flowing back when the bootstrap capacitor discharges, ensuring the normal operation of the bootstrap capacitor; when the external controller inputs control signals through the HIN and LIN pins, the driving chip controls the conduction and cutoff of the corresponding output pins HO and LO according to the signals.

[0027] The power supply in the overcurrent protection circuit uses the +3.3V voltage provided by the power supply circuit; the input signals are IA+, IB+, and IC+, which are connected to the circuit through resistors R15, R17, and R18 (with a resistance value of 1kΩ and an accuracy of 1%) respectively; the three resistors play the role of current limiting and voltage division, preventing excessive input current from damaging subsequent circuit components, and adjusting the input signals to an appropriate range for subsequent circuit processing; the signals pass through a low-pass filter composed of R10 (2kΩ, 1%) and R7 (18kΩ, 1%) and capacitor C12 (100nF) to filter out high-frequency noise in the input signals, making the signals input to the non-inverting input terminal (pin 3) of the operational amplifier U5 (LMV331) smoother and more stable; the output terminal (pin 4) of the operational amplifier is connected to the subsequent circuit, and according to the comparison result of the input signal and the reference voltage, it outputs a corresponding level signal. When the input signal is higher than the reference voltage, the operational amplifier outputs a high level; when the input signal is lower than the reference voltage, the operational amplifier outputs a low level; the signal output from pin 4 is connected to the light-emitting diode LED2 and R19 (5kΩ, 1%) through a resistor. The resistor R19 (1kΩ, 1%) is in series with LED2, playing the role of current limiting and protecting LED2 from being burned out by excessive current; when the operational amplifier outputs a high level, LED2 lights up, indicating that the circuit is in an overcurrent state; there are multiple AGND (analog ground) in the circuit, providing a unified reference potential for the entire circuit, ensuring that each component in the circuit can work normally and reducing signal interference.

Claims

1. A permanent magnet synchronous motor drive control and overcurrent protection circuit, characterized in that, It includes: An auxiliary power supply module, a three-phase current sampling circuit, a three-phase inverter circuit, an ACM32 microcontroller module, an RS_422 communication interface module, a drive circuit module, and an overcurrent protection circuit module; The auxiliary power supply module supplies power to the three-phase inverter circuit, the ACM32 microcontroller module, the RS_422 communication interface module, the drive circuit module, and the overcurrent protection circuit module; The three-phase inverter circuit, the ACM32 microcontroller module, the RS_422 communication interface module, the magnetic encoder interface circuit, the drive circuit module, and the overcurrent protection circuit module are interconnected; Both ends of the drive circuit module are respectively connected to the ACM32 microcontroller module and the three-phase inverter circuit; The overcurrent protection circuit module detects three-phase current signals in real time through the three-phase current sampling circuit and triggers a protection action according to the detection result.

2. The permanent magnet synchronous motor drive control and overcurrent protection circuit according to claim 1, characterized in that, The auxiliary power supply module includes: A +15V power supply unit, a +5V power supply unit, a +3.3V power supply unit, and a +1.65V reference voltage unit; Among them, the +15V power supply unit uses the switching power supply chip TPS5430DDA to achieve voltage conversion, and adjusts the output voltage through the inductor L1 and the voltage-dividing resistors R1 and R2; The +5V power supply unit conducts voltage conversion through the chip RY8310; The +3.3V power supply unit is step-down output by the linear voltage regulator AMS1117, and the power supply status is indicated by the LED3; The +1.65V reference voltage unit is generated by the operational amplifier U19.1 and the resistor voltage-dividing circuit, and the output is stabilized through the filter capacitor.

3. The permanent magnet synchronous motor drive control and overcurrent protection circuit according to claim 1, characterized in that, The three-phase current sampling circuit includes three single-phase current sampling units with the same structure, and each unit includes: A sampling resistor, an operational amplifier, a coupling capacitor, a current-limiting resistor, and a bypass capacitor; The operational amplifier amplifies the voltage signal across the sampling resistor through a negative feedback circuit and eliminates ground loop interference through single-point grounding.

4. The permanent magnet synchronous motor drive control and overcurrent protection circuit according to claim 1, characterized in that, The three-phase inverter circuit uses six power switch tubes to form a three-phase bridge arm, and a 10mΩ resistor is connected in series to the source of the lower transistor of each bridge arm to detect the phase current; PGND is set in the three-phase inverter circuit to reduce ground wire noise, and a gate drive protection circuit is used to suppress voltage spikes.

5. The permanent magnet synchronous motor drive control and overcurrent protection circuit according to claim 1, characterized in that The ACM32 microcontroller module is connected to the magnetic encoder interface circuit through the SPI bus and receives the position signal output by the magnetic encoder; The microcontroller module exchanges data with the RS_422 communication interface module through the UART2_TX and UART2_RX pins, and outputs a control signal to the drive circuit module through the GPIO pins.

6. The permanent magnet synchronous motor drive control and overcurrent protection circuit according to claim 1, characterized in that, The drive circuit module uses the drive chip FD6288T, whose input terminal receives the PWM signal of the microcontroller, and the output terminal is connected to the three-phase inverter circuit; The drive circuit module realizes the boost of the drive voltage of the upper bridge arm power tube through a bootstrap capacitor and a diode.

7. The permanent magnet synchronous motor drive control and overcurrent protection circuit according to claim 1, wherein The overcurrent protection circuit module includes: A low-pass filter, an operational amplifier, a reference voltage comparison unit, and an LED indication circuit; The operational amplifier compares the three-phase current signal with the reference voltage. When the output is high, it triggers the LED2 to light up and sends a protection signal to the microcontroller module to cut off the drive signal.

8. The permanent magnet synchronous motor drive control and overcurrent protection circuit according to claim 2, wherein The input power supply of the +15V power supply unit forms a freewheeling loop through the inductor L1 and the diode D1, and eliminates the ripple noise through multiple filter capacitors.

9. The permanent magnet synchronous motor drive control and overcurrent protection circuit according to claim 3, characterized in that The gain of the single-phase current sampling unit is determined by the ratio of the feedback resistor R33 to the sampling resistor R23, and the gain calculation formula is: 。 10. The permanent magnet synchronous motor drive control and overcurrent protection circuit according to claim 7, wherein The cut-off frequency of the low-pass filter is set by the values of the resistor and the capacitor, and is used to filter out high-frequency noise and smooth the input signal.

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