Vector driving circuit of high-power brushless motor

Abstract

The invention discloses a high-power brushless motor vector driving circuit which comprises a CAN bus communication module, a single chip microcomputer, three parallel driver chips, a three-phase circuit, a high-power brushless motor, a sampling circuit and an encoder. The CAN bus communication module is used for supporting information interaction between the single-chip microcomputer and the outside. The single-chip microcomputer is used for outputting PWM signals and controlling the driver chip to generate driving voltage. The three-phase circuit receives driving voltage control and supplies power to the high-power brushless motor at the output end; the sampling circuit carries out voltage sampling on the three-phase circuit and transmits a result to the single-chip microcomputer. The encoder transmits the position and speed of the high-power brushless motor to the single-chip microcomputer. According to the invention, the CAN bus communication module is used for realizing a multi-machine communication function, and the operation of a three-phase circuit and a high-power brushless motor is finely adjusted through feedback of two closed loops, so that the requirements of high precision and high torque are met; the circuit structure is optimized, electricity utilization and a large number of Hall sensors are avoided, and the circuit stability is improved.

Description

Technical Field

[0001] The invention relates to the technical field of brushless motors, and in particular to a high-power brushless motor vector drive circuit. Background Art

[0002] Brushless motors are advanced electric motors that have been widely used in industrial automation, consumer electronics, automobiles, medical equipment and other fields due to their high efficiency, reliability and low maintenance. Brushless motors can be divided into three types according to power level: low power, medium power and high power. High power brushless motors are widely used in industrial equipment, transportation vehicles and power generation equipment that require high power output.

[0003] At present, there are two main ways to use high-power brushless motors: first, use electronic regulation, that is, use an electronic speed regulator to receive signals from a remote control or controller, convert these signals into current and voltage and output them to the brushless motor, thereby effectively controlling the speed and torque of the brushless motor; second, use a single-chip microcomputer, multiple Hall sensors and multiple drive circuits to drive and control the brushless motor, and at the same time, the corresponding instructions or programs can be input through the single-chip microcomputer for regulation.

[0004] However, these measures currently adopted contain at least the following three problems: 1) When using an ESC, it is difficult to control the brushless motor at low speed due to the performance limitations of the ESC itself; 2) Insufficient performance. Using more Hall sensors will cause a greater drift effect and low accuracy, making it difficult to meet high-precision and high-torque requirements; 3) In some scenarios, there may be multiple high-power brushless motors, and there is a lack of interaction between multiple high-power brushless motors. Summary of the invention

[0005] In view of the above three problems, the purpose of the present invention is to propose a high-power brushless motor vector drive circuit, which uses a CAN bus communication module to realize multi-machine communication of multiple high-power brushless motors; it also uses two closed-loop feedbacks to obtain relevant data of the three-phase circuit and the high-power brushless motor respectively and submit them to the single-chip microcomputer for unified analysis, so as to facilitate more refined adjustment of circuit parameters and operating data of the high-power brushless motor, so as to meet the requirements of high precision and high torque; in addition, the circuit structure is optimized to avoid the use of electric regulation and a large number of Hall sensors, thereby improving the stability of the circuit and facilitating refined control.

[0006] This is achieved through the following technical solutions: A high-power brushless motor vector drive circuit comprises a CAN bus communication module, a single-chip microcomputer, three parallel driver chips, a three-phase circuit, a high-power brushless motor, a sampling circuit and an encoder; wherein the CAN bus communication module is equipped with a CAN transceiver chip, the CAN transceiver chip is connected to the single-chip microcomputer to support the single-chip microcomputer to interact with external information; the single-chip microcomputer is used to output three corresponding PWM signals to the three parallel driver chips, each PWM signal is used to drive the corresponding driver chip to generate each driving voltage; the three-phase circuit comprises three identical phase circuits, the input end of each phase circuit receives the driving control of the corresponding driving voltage, and the output end of each phase circuit is connected to the high-power brushless motor for power supply; the sampling circuit is used to sample the voltage of each phase circuit in the three-phase circuit and transmit the sampling result to the single-chip microcomputer to form a first closed-loop feedback; the encoder is respectively connected to the high-power brushless motor and the single-chip microcomputer, and is used to transmit the position and speed of the high-power brushless motor to the single-chip microcomputer to form a second closed-loop feedback.

[0007] The CAN bus communication module can realize data transmission between the microcontroller and the outside world, thereby meeting the scenario requirements of interaction between multiple high-power brushless motors; at the same time, two closed-loop feedbacks are set up to obtain relevant data of the three-phase circuit and the high-power brushless motor respectively, and the data is submitted to the microcontroller for unified analysis, which is convenient for more refined adjustment of the operation of the high-power brushless motor, thereby meeting the requirements of high precision and high torque.

[0008] Preferably, two identical MOS tubes are built in each phase circuit, and the two MOS tubes are connected by a half-bridge topology structure, and the intermediate node of the half-bridge topology structure is connected to the corresponding driver chip. Two MOS tubes are used in each phase circuit to form a half-bridge topology structure, which can achieve efficient voltage switching and current control. The half-bridge topology structure is simple, reliable and suitable for high-power applications, and can meet the performance requirements of high efficiency and high reliability.

[0009] Preferably, in the half-bridge topology, a voltage stabilizing circuit is connected in parallel between the sources of the two MOS tubes, and the voltage stabilizing circuit includes a plurality of voltage stabilizing capacitors connected in parallel, and the parameters of each voltage stabilizing capacitor are the same. In the half-bridge topology, the design of connecting the voltage stabilizing capacitors in parallel between the sources of the two MOS tubes has the advantages of voltage stabilization filtering, improving stability and anti-interference ability, protecting the MOS tube, and improving dynamic response ability, thereby making the operation of the overall circuit more stable and accurate.

[0010] Preferably, the sampling circuit includes three sampling branches with the same structure, which are used to obtain the current of the corresponding three phase circuits. Each sampling branch includes a sampling resistor, an operational amplifier and a regulating power supply. The input end of the operational amplifier is connected to the near-ground end of the corresponding phase circuit through the sampling resistor. The regulating power supply is connected in parallel to the input end of the operational amplifier to adjust the voltage obtained by sampling the operational amplifier. The output end of the operational amplifier is connected to the single-chip microcomputer. The sampling resistor is connected to the near-ground end of the corresponding phase circuit, which can eliminate the common mode interference of the PWM signal, improve the accuracy and stability of the signal, and then use the regulating power supply to effectively control the working sampling range of the operational amplifier.

[0011] Preferably, the encoder includes a power supply pin, a ground pin, an SCL pin and an SDA pin; two filter capacitors are connected in parallel between the power supply pin and the ground pin, the SCL pin and the SDA pin are connected to the single-chip microcomputer through the I2C bus, and a pull-up resistor is connected in parallel between the SCL pin and the SDA pin to pull up the level. The two filter capacitors can reduce the impact of voltage fluctuations on the performance of the encoder, and combined with the I2C bus with strong anti-interference ability, the operating data of the high-power brushless motor can be effectively and stably and accurately transmitted to the single-chip microcomputer.

[0012] Preferably, the CAN transceiver chip exchanges data with the single-chip microcomputer through the TXD pin and the RXD pin, and connects the CAN bus through the CANH pin and the CANL pin to support multi-machine interaction. At the same time, the CANH pin and the CANL pin are also connected through a terminal resistor. The CAN transceiver can be connected to other chips or other transceivers that communicate with the bus through the CAN bus, thereby realizing multi-machine communication.

[0013] Preferably, the single chip microcomputer is connected to an external crystal oscillator circuit, and the crystal oscillator of the external crystal oscillator circuit is at least 8 MHz. A crystal oscillator of at least 8 MHz can provide an accurate clock signal, thereby achieving fine time control and meeting high-precision requirements.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The technical solution of the present invention utilizes a CAN bus communication module to realize multi-machine communication of multiple high-power brushless motors; it also utilizes two closed-loop feedbacks to respectively obtain relevant data of the three-phase circuit and the high-power brushless motor and submit them to a single-chip microcomputer for unified analysis, thereby facilitating more refined adjustment of circuit parameters and operating data of the high-power brushless motor, thereby meeting the requirements of high precision and high torque; in addition, the circuit structure is optimized to avoid the use of electric regulation and a large number of Hall sensors, thereby improving the stability of the circuit and facilitating refined control. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of a high-power brushless motor vector drive circuit; Figure 2 It is a structural schematic diagram of a voltage stabilizing circuit; Figure 3 A schematic diagram of a structure for connecting a driver chip and a corresponding phase circuit; Figure 4 It is a structural schematic diagram of an external crystal oscillator circuit; Figure 5 It is a structural diagram of an encoder connected to a single-chip microcomputer; Figure 6 A schematic diagram of a circuit structure for sampling a phase circuit in a sampling circuit; Figure 7 The figure is a schematic diagram of the structure of a CAN transceiver chip connected to a CAN bus. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0017] like Figure 1 The figure shows a schematic diagram of the structure of a high-power brushless motor vector drive circuit. The single-chip microcomputer and driver chip are used to control the operation of the three-phase circuit. At the same time, through the dual closed-loop feedback of the sampling circuit and the encoder, the fine adjustment of the three-phase circuit and the high-power brushless motor is effectively achieved.

[0018] The high-power brushless motor vector drive circuit mainly includes a CAN bus communication module, a single-chip microcomputer, three parallel driver chips, a three-phase circuit, a high-power brushless motor, a sampling circuit and an encoder. The CAN bus communication module has a built-in CAN transceiver chip, such as the TJA1050T chip. The TXD pin of the CAN transceiver chip is connected to the single-chip microcomputer, and the TXD pin is used to send signals to the single-chip microcomputer. The RXD pin is connected to the CAN bus, and the RXD pin is used to receive data from the CAN bus, thereby allowing multiple single-chip microcomputers in multiple high-power brushless motor vector drive circuits to interact with each other through the CAN bus. The CANH pin and CANL pin of the CAN transceiver chip are connected separately. It should be noted that the CAN bus is a serial communication protocol with multiple nodes set on the bus, allowing multiple devices to connect to the corresponding nodes, so that multiple machines can communicate on the same bus, with the advantages of high reliability, standardized protocols and flexible data transmission.

[0019] like Figure 7The figure shows a schematic diagram of the structure of a CAN transceiver chip connected to a CAN bus. The CAN transceiver chip exchanges data with the microcontroller through the TXD pin and the RXD pin, and connects to the CAN bus through the CANH pin and the CANL pin to support multi-machine interaction. At the same time, the CANH pin and the CANL pin are also connected through a terminal resistor. Taking the TJA1050T chip as an example, the transceiver chip mainly includes 8 pins: TXD, GND, VCC, RXD, S, CANH, CANL and VREF, and the VREF pin is disconnected; the TXD pin is used to send signals to the microcontroller, and the RXD pin is used to receive signals from the microcontroller; the CANH pin and the CANL pin are used to connect to the CAN bus, and data can be exchanged with other chips connected to the bus through the CAN bus. At the same time, the CANH pin and the CANL pin are also connected through a 120Ω resistor R10. The resistor R10 is used as a terminal resistor to reduce signal reflection and impedance matching; the S pin and the GND pin are both grounded; the VCC pin receives a 5V power supply and is connected in parallel to the GND pin through a 0.1uF capacitor C17 to filter out noise and improve stability.

[0020] In the case of multiple high-power brushless motor drive circuits, each high-power brushless motor drive circuit can be connected via a CAN bus. The CAN bus connects each transceiver chip of each high-power brushless motor drive circuit, and the data of each corresponding microcontroller can be interacted, thereby supporting data interaction and data statistics of different drive circuits.

[0021] In this embodiment, the single-chip microcomputer is used to output three corresponding PWM signals to three parallel driver chips, and each PWM signal is used to drive the corresponding driver chip to generate each driving voltage. For example, the single-chip microcomputer can use the Stm32f103c8t6 single-chip microcomputer, which has a maximum main frequency of 72MHz to ensure the operating performance, and has a built-in 12-bit ADC analog-to-digital converter for converting voltage signals into digital signals. At the same time, three pins can be used to output PWM signals respectively and transmit them to three driver chips. The driver chip can use the EG2104S chip. The three driver chips are all powered by a DC power supply, and then generate corresponding voltage waveforms based on the corresponding PWM signals, that is, generate each driving voltage, thereby driving the three-phase circuit to operate.

[0022] like Figure 4The figure shows a schematic diagram of the structure of an external crystal oscillator circuit. In order to provide an accurate clock signal, thereby achieving fine time control and meeting high-precision requirements, the single-chip microcomputer also needs to be connected to an external crystal oscillator circuit, and the crystal oscillator of the external crystal oscillator circuit is at least 8MHz. The external crystal oscillator circuit includes a crystal oscillator X1 of at least 8MHz, capacitors C18 and C19, the OSC oscillator input pin and the OSC oscillator output pin of the single-chip microcomputer are grounded through capacitors C18 and C19 respectively, the crystal oscillator is connected between the OSC oscillator input pin and capacitor C18 and between the OSC oscillator output pin and capacitor C19 respectively, and capacitors C18 and C19 are responsible for filtering to reduce noise interference.

[0023] In this embodiment, the three-phase circuit includes three identical phase circuits, the input end of each phase circuit receives the driving control of the corresponding driving voltage, and the output end of each phase circuit is connected to the high-power brushless motor for power supply. Two identical MOS tubes are built in each phase circuit, and the two MOS tubes are connected using a half-bridge topology structure, one is an upper bridge arm MOS tube, and the other is a lower bridge arm MOS tube. The intermediate node of the upper bridge arm MOS tube and the lower bridge arm MOS tube is connected to the corresponding driver chip, thereby converting the driving voltage into AC power for powering the high-power brushless motor. Two MOS tubes are used in each phase circuit to form a half-bridge topology structure, which can achieve efficient voltage switching and current control. The half-bridge topology structure is simple, reliable and suitable for high-power applications, and can meet the performance requirements of high efficiency and high reliability.

[0024] like Figure 3As shown, it is a structural schematic diagram of connecting a driver chip and a corresponding phase circuit. The driver chip adopts the EG2104S chip, and the two MOS tubes Q1 and Q2 of the phase circuit both adopt HYG025N06LS1C2. The VCC pin of the EG2104S chip receives a 12V power supply, one end of the VCC pin is grounded to GND through a 100nF bypass capacitor C21, and the other end of the VCC pin is connected to the VS pin of the EG2104S chip through a diode D2FR107W and a 10uF filter capacitor C22. The diode D2 can be FR107W. The IN pin of the EG2104S chip receives the PWM1 signal sent by the microcontroller. The #SD pin of the EG2104S chip is used to receive the EN MOS signal sent by the microcontroller. The HO pin of the EG2104S chip is connected to the S pole of the MOS tube Q1 through the GH1 node and the 22Ω resistor R15. The LO pin of the EG2104S chip is connected to the S pole of the MOS tube Q2 through the GL1 node and the 22Ω resistor R16. The EG2104S chip can control whether to start driving the phase circuit through the HO pin and the LO pin based on the EN MOS signal. The D pole of the MOS tube Q1 receives power from VIN, the S pole of the MOS tube Q1 is connected to the D pole of the MOS tube Q2, and the two poles are connected to the high-power brushless motor through the M0_OUT1 node for power supply. The S pole of the MOS tube Q2 is grounded through a 5mΩ current detection resistor R21, and both ends of the current detection resistor R21 are connected to the sampling circuit to realize the sampling circuit sampling of the phase circuit.

[0025] In this embodiment, in the half-bridge topology, a voltage stabilizing circuit is connected in parallel between the sources of the two MOS tubes. The voltage stabilizing circuit includes a plurality of voltage stabilizing capacitors connected in parallel, and the parameters of each voltage stabilizing capacitor are the same. Figure 2 The figure shows a schematic diagram of the structure of a voltage stabilizing circuit. The voltage stabilizing circuit is formed by connecting 12 22uF voltage stabilizing capacitors in parallel. When the MOS tube is turned on, it can better prevent the circuit from being burned by the large instantaneous voltage and current, thereby improving the stability, anti-interference ability and protecting the MOS tube, so that it can meet the needs of fast dynamic response.

[0026] In this embodiment, the sampling circuit is used to sample the voltage of each phase circuit in the three-phase circuit, and then transmit the sampling result to the single-chip microcomputer to form a first closed-loop feedback. The sampling circuit includes three sampling branches with the same structure, which are used to obtain the current of the corresponding three phase circuits. Each sampling branch includes a sampling resistor, an operational amplifier and a regulating power supply. The input end of the operational amplifier is connected to the near-ground end of the corresponding phase circuit through the sampling resistor. The regulating power supply is connected in parallel to the input end of the operational amplifier to adjust the voltage obtained by the sampling of the operational amplifier. The output end of the operational amplifier is connected to the single-chip microcomputer. For example, by connecting a 5mΩ sampling resistor to the near-ground end of the lower bridge arm MOS tube, the common-mode interference generated by the PWM signal can be eliminated, and the accuracy and stability of the signal can be improved. The circuit samples the EG8546 operational amplifier, amplifies the sampled voltage by 50 times, and then adds a 1.65V regulating power supply to achieve a current sampling range between 0-3.3V. Then the ADC mode converter in the single-chip microcomputer reads the sampling result for conversion, and the value of the current in the three-phase circuit can be calculated.

[0027] like Figure 6 As shown, it is a circuit structure schematic diagram for sampling a phase circuit in a sampling circuit. The input end is connected to both ends of the current sampling resistor R21 for sampling, and then the amplified voltage is transmitted to the single-chip microcomputer through the ADC node after reverse operational amplification by the EG8546 amplifier. The EG8546 amplifier includes a positive input end, a negative input end, a positive power supply end, a ground end and an output end. The positive input end and the negative input end are respectively connected to the resistor R21 and the negative input end is grounded through the resistor R29. The positive input end is also connected in series with a 2KΩ resistor for voltage division protection. A 2.2nF capacitor is also provided between the positive input end and the negative input end for DC isolation. The 1.65V power supply is connected in parallel to the positive input end through the 20KΩ resistor R27 to adjust the sampling range of the operational amplifier. The negative input end is also connected to the output end through the 20KΩ resistor R30, thereby forming a negative feedback loop. The ground terminal of the EG8546 amplifier is grounded, the positive power supply terminal receives +3.3V power supply and is also grounded through a 100nF capacitor C29 to reduce noise interference. The output terminal of the EG8546 amplifier is gain-adjusted through a 20Ω resistor R28 and then connected to the microcontroller.

[0028] In this embodiment, the encoder is respectively connected to the high-power brushless motor and the single-chip microcomputer, and is used to transmit the position and speed of the high-power brushless motor to the single-chip microcomputer to form a second closed-loop feedback. The single-chip microcomputer can determine the minimum speed and position accuracy of the high-power brushless motor based on the real-time transmitted position data and speed data. Combined with the voltage data and current data obtained in the sampling circuit, the various operating parameters of the high-power brushless motor can be clearly and accurately obtained, so that based on these parameters, the PWM signal of the single-chip microcomputer can be adjusted to further improve the operating speed or position accuracy of the high-power brushless motor.

[0029] like Figure 5 As shown, it is a schematic diagram of the structure of an encoder connected to a single-chip microcomputer. The encoder can use the AS5600-ASOM chip, which is provided with a power supply pin, a GND pin, an OUT pin, a DIR pin, a PGO pin, an SCL pin, and an SDA pin; the power supply pin includes a VDD5V pin and a VDD3V3 pin, which correspond to two power supply voltages of 5V and 3.3V respectively, and can be selected according to the actual use conditions. Taking the use of 3.3V power supply as an example, two filter capacitors are connected in parallel between the power supply pin and the ground pin, which are 0.1uF capacitor C33 and 1uF capacitor C34, respectively, to filter out noise and stabilize the power supply voltage. The OUT pin is disconnected, and the SCL pin and the SDA pin are connected to the single-chip microcomputer through the I2C bus. The SCL pin and the SDA pin are connected in parallel with a pull-up resistor R42 and a resistor R41 of 10kΩ each and powered by a 3.3V power supply. The two pull-up resistors are used to pull the level high, thereby controlling whether the two pins transmit data. The DIR pin is grounded, and the PGO pin is grounded through a 10KΩ resistor R43. R43 is used as a pull-down resistor. When the power supply is not stable, the PGO pin remains at a low level, indicating that the power supply is not ready. The two filter capacitors can reduce the impact of voltage fluctuations on the performance of the encoder. Combined with the I2C bus with strong anti-interference ability, the operating data of the high-power brushless motor can be effectively and accurately transmitted to the microcontroller.

[0030] In summary, the present invention utilizes the CAN bus communication module to realize multi-machine communication of multiple high-power brushless motors; it also utilizes two closed-loop feedbacks to respectively obtain relevant data of the three-phase circuit and the high-power brushless motor and submit them to the single-chip microcomputer for unified analysis, so as to facilitate more refined adjustment of circuit parameters and operation data of the high-power brushless motor, thereby meeting the requirements of high precision and high torque; in addition, the circuit structure is optimized to avoid the use of electric regulation and a large number of Hall sensors, thereby improving the stability of the circuit and facilitating refined control, which is significantly progressive.

[0031] The above embodiments are only for illustrating the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A high-power brushless motor vector drive circuit, characterized in that: It includes CAN bus communication module, single chip microcomputer, three parallel driver chips, three-phase circuit, high-power brushless motor, sampling circuit and encoder; Among them, the CAN bus communication module has a built-in CAN transceiver chip, which is connected to the single-chip microcomputer to support the interaction of the single-chip microcomputer with external information; the single-chip microcomputer is used to output corresponding three PWM signals to three parallel driver chips, and each PWM signal is used to drive the corresponding driver chip to generate each driving voltage; the three-phase circuit includes three identical phase circuits, the input end of each phase circuit receives the driving control of the corresponding driving voltage, and the output end of each phase circuit is connected to the high-power brushless motor for power supply; the sampling circuit is used to sample the voltage of each phase circuit in the three-phase circuit and transmit the sampling result to the single-chip microcomputer to form a first closed-loop feedback; the encoder is respectively connected to the high-power brushless motor and the single-chip microcomputer, and is used to transmit the position and speed of the high-power brushless motor to the single-chip microcomputer to form a second closed-loop feedback.

2. A high-power brushless motor vector drive circuit according to claim 1, characterized in that: Two identical MOS tubes are built in each phase circuit. The two MOS tubes are connected by a half-bridge topology structure, and the middle node of the half-bridge topology structure is connected to the corresponding driver chip.

3. A high-power brushless motor vector drive circuit according to claim 2, characterized in that: In the half-bridge topology, a voltage stabilizing circuit is connected in parallel between the sources of the two MOS tubes. The voltage stabilizing circuit includes a plurality of voltage stabilizing capacitors connected in parallel, and the parameters of each voltage stabilizing capacitor are the same.

4. A high-power brushless motor vector drive circuit according to claim 1, characterized in that: The sampling circuit includes three sampling branches with the same structure, which are used to obtain the current of the corresponding three phase circuits. Each sampling branch includes a sampling resistor, an operational amplifier and a regulating power supply. The input end of the operational amplifier is connected to the near-ground end of the corresponding phase circuit through the sampling resistor. The regulating power supply is connected in parallel to the input end of the operational amplifier to adjust the voltage obtained by sampling the operational amplifier. The output end of the operational amplifier is connected to the single-chip microcomputer.

5. A high-power brushless motor vector drive circuit according to claim 1, characterized in that: The encoder includes a power supply pin, a ground pin, an SCL pin and an SDA pin; two filter capacitors are connected in parallel between the power supply pin and the ground pin, the SCL pin and the SDA pin are connected to the microcontroller through the I2C bus, and a pull-up resistor is connected in parallel between the SCL pin and the SDA pin to pull up the level.

6. A high-power brushless motor vector drive circuit according to claim 1, characterized in that: The CAN transceiver chip exchanges data with the microcontroller through the TXD pin and RXD pin, and connects the CAN bus through the CANH pin and CANL pin to support multi-machine interaction. At the same time, the CANH pin and CANL pin are also connected through a terminal resistor.

7. A high-power brushless motor vector drive circuit according to claim 1, characterized in that: The single chip microcomputer is connected to an external crystal oscillator circuit, and the crystal oscillator of the external crystal oscillator circuit is at least 8MHz.

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