阅读说明：本技术 一种数字化智能电机驱动器及驱动方法 (Digital intelligent motor driver and driving method ) 是由 蒋凯 毋蒙 张伟 杨健 霍红梅 刘亭剑 计旭 于 2021-01-08 设计创作，主要内容包括：本发明涉及数字化智能电机驱动器及驱动方法,该电机驱动器具有磁耦隔离、二次电源变换、霍尔换相控制、过压泄放抑制、过流限流保护、短路软关断保护、死区时间自适应优化、驱动参数智能调节等功能,能够根据数字信息处理平台传来的差分式PWM信号及方向信号,实现一路舵机的驱动控制,能够对舵机运行过程中反电动势造成的过压浪涌进行泄放抑制,能够对舵机工作电流进行限流,能够在短路故障时及时安全的关断功率电路,能够根据功率回路电流大小自适应调节死区时间,能够根据负载条件自动调节驱动参数,能够通过差分总线实时反馈舵机驱动器内部温度、电流,能够对CAN接口反馈位置传感器和电机霍尔进行供电。(The invention relates to a digital intelligent motor driver and a driving method, the motor driver has the functions of magnetic coupling isolation, secondary power supply transformation, Hall phase-changing control, overvoltage discharge inhibition, overcurrent current-limiting protection, short-circuit soft turn-off protection, dead-zone time self-adaptive optimization, driving parameter intelligent regulation and the like, can realize the driving control of a path of steering engine according to a differential PWM signal and a direction signal transmitted by a digital information processing platform, can inhibit the discharge of overvoltage surge caused by counter electromotive force in the operation process of the steering engine, can limit the working current of the steering engine, can timely and safely turn off a power circuit when in short-circuit fault, can adaptively regulate the dead-zone time according to the current of a power loop, can automatically regulate the driving parameter according to the load condition, can feed back the internal temperature and current of the steering engine driver in real time through a differential bus, the CAN interface feedback position sensor and the motor Hall CAN be powered.)

1. A digital intelligent motor driver is characterized in that: comprises a power board, a conditioning board and a structural body;

the power board adopts an aluminum-based circuit board for realizing the functions of electric energy conversion, power driving, energy release and current sampling, and the aluminum-based circuit board is fixedly connected with a heat dissipation structure body by utilizing the advantage of good heat dissipation of the aluminum-based circuit board, so that good heat dissipation of the power driver is realized;

the conditioning board is used for realizing the functions of interface signal processing, digital signal conversion, state monitoring and fault protection;

the structure body is mainly used for fixedly connecting the power plate and the conditioning plate and providing a good heat dissipation carrier for the power device.

2. The digital intelligent motor driver as claimed in claim 1, wherein: the power board comprises a backflow prevention circuit, a discharge circuit, a power driving circuit, a power bridge circuit, an overcurrent protection circuit and a current isolation sampling circuit, and is used for realizing the functions of electric energy conversion, power driving, energy discharge and current sampling;

the backflow preventing circuit is designed independently aiming at the power circuit and the control circuit, a power diode with 1200V withstand voltage and 120A rated overcurrent capacity is selected as a power circuit part and is connected in series into a power supply positive line of the power driver, and the backflow preventing circuit is used for preventing the current of a power bus VP from flowing backwards to the input end of a power supply when a motor is braked; the control circuit part selects a power diode with the voltage resistance of 250V and the rated overcurrent capacity of 6A, and the power diode is connected in series with a power source positive line of the power driver and used for preventing the current of the control bus VK from flowing back to a power supply input end;

the leakage circuit adopts PMOS as a power control device and adopts a power resistor as a dissipation load, when the voltage of the backward stage of the backward flow prevention power diode is more than 3V higher than the voltage of the forward stage of the diode, the PMOS device is conducted, and the current on the power bus VP is leaked through the resistor, so that the further rise of the voltage of the bus is avoided, wherein the leakage resistor adopts an external mode;

the power driving circuit adopts BM6104-FV as a driving chip, and the chip calculates the output PWM signal according to the Hall commutation logic circuit, amplifies the control signal and outputs a gate driving signal for the three-phase bridge circuit;

the power bridge circuit is a three-phase power bridge circuit and is formed by 3 SiC MOSFET half-bridge power modules with withstand voltage of more than or equal to 1200V and overcurrent capacity of more than or equal to 400A in a bridge connection mode, and a nonpolar capacitor with a capacitance value of more than or equal to 100uF and withstand voltage of more than or equal to 1200V is connected in parallel on a bus of the bridge circuit;

the over-current protection circuit determines drain-source voltage corresponding to over-current by adjusting the value of a divider resistor by utilizing the output characteristic of the SiC MOSFET and combining a desaturation detection circuit built in the power driving chip BM 6104-FV;

the current isolation sampling circuit adopts an ACS712 isolation current sampling chip to sample current input by a power supply, and the current is modulated into PWM waves through a PWM modulation circuit and output through a differential interface circuit, so that the current isolation sampling circuit is used for monitoring the current in real time by a digital processing platform.

3. The digital intelligent motor driver as claimed in claim 2, wherein: the BM6104-FV is integrated with a short-circuit protection function and an active clamping output function, the short-circuit protection function can detect the drain-source current of the SiC MOSFET, when overcurrent occurs, soft shutdown is performed through a large resistance loop PROOUT, if the current returns to normal in the buffer time, the subsequent driving chip returns to normal operation, if overcurrent is detected after the buffer time, short circuit is determined, and forced shutdown is performed; the soft turn-off circuit can limit overcurrent in time on one hand and reserve buffer on the other hand, so that the situation that a power device or even the whole driver is broken down by limit peak voltage generated by overhigh transient current change rate due to instantaneous turn-off of an overcurrent power loop is avoided; the active clamping position output function is to open the active Miller clamping position MOSFET after the power device is turned off according to a time sequence in the normal work of the driving circuit, absorb interference voltage generated on the driving circuit by the high-frequency switch and bridge arm crosstalk through the Miller capacitor, and simultaneously turn off the active Miller clamping position MOSFET before the power device is turned on, and disconnect the Miller capacitor from the gate source electrode, thereby avoiding influencing the high-speed switch of the SiC MOSFET.

4. A digital intelligent motor driver as claimed in claim 3, wherein: the conditioning board is made of FR4 epoxy resin board.

5. The digital intelligent motor driver as claimed in claim 4, wherein: the conditioning board comprises a signal processing circuit, a differential interface circuit, a magnetic isolation interface circuit, an isolation power supply conversion circuit, a secondary power supply conversion circuit, a Hall interface circuit, a Hall commutation logic conversion circuit, a current sampling conversion circuit and a temperature sampling circuit, and is used for realizing the functions of interface signal processing, digital signal conversion, state monitoring and fault protection;

the main control chip of the signal processing circuit is controlled by a DSP (digital signal processor), receives a current sampling signal, a temperature sampling signal and an instruction signal which are sent by a differential circuit and are in a PWM (pulse-width modulation) form, and obtains a corresponding PWM control signal and an F/R (frequency/direction) signal to a driving circuit through operation;

the differential interface circuit adopts AM26LS31 and AM26LS32 as differential interface chips, and the device is compatible with an RS422 interface level form, wherein the AM26LS31 is used for sending PWM form current sampling signals and PWM form temperature sampling information and converting TTL level signals into RS422A differential signals; the AM26LS32 is used for receiving the differential steering engine control PWM signal and the FR direction control signal and converting the RS422A differential signal into a TTL signal;

the magnetic isolation switching circuit adopts an ADUM1401 device which is provided with three receiving channels and 1 sending channel and can receive a steering control PWM signal and an FR direction signal transmitted by a differential interface circuit.

The isolation power supply conversion circuit is used for converting a 12V voltage signal converted by the secondary power supply conversion circuit into a 5V isolation voltage signal for supplying power to the magnetic isolation conversion circuit, the differential interface circuit and the feedback position sensor;

the secondary power supply conversion circuit is used for converting the voltage of a power bus into a 12V control power supply, has the power output capacity of more than or equal to 5W, supplies power for the power driver and the Hall sensor, and converts a non-isolated 5V signal through the LDO (low dropout regulator) to be used for supplying power to the power end of the magnetic isolation chip;

the Hall interface circuit is used for receiving a Hall signal of the motor, filtering by adopting an RC filter circuit, protecting a port by using a Zener diode, and pulling up a 10k ohm resistor to a Hall power supply from the input end of the Hall interface circuit;

the Hall commutation logic conversion circuit carries out logic operation according to the Hall signal, the PWM signal and the direction signal and outputs 6 paths of PWM control signals according to a limited unipolar driving mode;

the current sampling conversion circuit converts a voltage signal output by the current sampling circuit into a 2KHz PWM wave and outputs the PWM wave to the differential interface circuit;

the temperature sampling circuit adopts a temperature sensor in a PWM interface form; and the temperature signal output by the PWM is output after differential conversion.

6. The digital intelligent motor driver as claimed in claim 5, wherein: the PWM interface type temperature sensor adopts isolated 5V power supply, and the temperature sampling range is-55-150 ℃.

7. The driving method of a digital intelligent motor driver as claimed in claim 6, wherein: outputting a direction signal and a PWM driving signal according to a certain logic sequence according to a position feedback signal, a temperature feedback signal and a current sampling signal of a position sensor, and specifically comprising the following steps:

step one, after an input power supply is powered on, an information processing platform reads a rudder feedback position signal, and within 50ms of power-on, a PWM driving signal needs to be kept at a low level; after 50ms, a PWM signal can be output according to the rudder control requirement;

step two, if the steering engine needs to rotate in the forward direction, the FR signal outputs a high level; if the steering engine needs to rotate in a negative direction, the FR signal outputs a low level;

the output duty ratio of the steering engine is determined by the duty ratio of a PWM signal, the carrier period of the PWM signal is configured through an information processing platform, the configurable interval is 2 k-20 kHz, and the duty ratio range is (0-100%);

in the steering engine control process, the information processing platform interprets steering engine feedback position information, an overcurrent protection signal, a temperature signal and a current sampling signal in real time, diagnoses the steering engine working state through the signals, adjusts the duty ratio and dead time of a PWM signal in real time, and outputs a corresponding steering control PWM signal and a corresponding direction signal.

Technical Field

The invention relates to the technical field of motor control, in particular to a digital intelligent motor driver and a driving method thereof, and particularly mainly relates to a three-phase full-bridge digital intelligent driver based on a SiC MOSFET and a driving method thereof.

Background

The permanent magnet brushless direct current motor has the advantages of small volume, high efficiency, high power density, reliable structure, easy use and control and the like, and is widely applied to an aircraft rudder control system represented by an unmanned aerial vehicle and a spacecraft. At present, a steering control system mainly adopts a split design scheme of a steering engine controller and a steering engine executing mechanism. The steering engine controller is generally composed of an information processing circuit, a power driving circuit and a mechanism part, and mainly achieves the functions of digital signal processing, algorithm resolving, power signal driving amplification and the like. The steering engine executing mechanism generally comprises a motor, a speed reducing transmission mechanism and a feedback device, and is used for finally executing a steering control command, outputting required torque and steering deflection speed, and deflecting a control surface to an appointed steering deflection position. According to different electric parameters of the steering engine, the output voltage of the steering engine controller has a wide variation range from 6V to more than 400V.

With the development of unmanned planes and multi-electric planes, higher power and efficiency have become one of the main research directions for onboard motor drives. Although the existing Si MOSFET has high switching speed, the voltage resistance and the current resistance are limited, and high-power output cannot be realized, and the IGBT has turn-off trailing current, so the switching speed is slow, and the switching loss is large. The high voltage resistance and the high switching speed of the SiC MOSFET can effectively improve the power and the efficiency of the motor driver, but the higher switching speed and the higher power put higher demands on the quick response capability and the quick fault protection capability of the driver.

In addition, the steering engine controller has a power driving circuit and an information processing circuit inside, and the problem of electromagnetic interference caused by the high-speed switch of the SiC MOSFET power driving circuit can influence the work of the information processing circuit part, and even influence the work of a superior system. The method has higher requirements on the anti-interference design of the steering engine controller information processing circuit and a superior system. How to break through the design bottleneck of a steering engine controller, solve the difficult problem of SiC MOSFET drive design, and improve the reliability and the anti-interference performance of a rudder system, which becomes a hot direction of industry exploration.

With the development of electronic technology, the digital signal processing circuit is designed in a digitalized, intelligentized and integrated manner to become a development trend, and a new idea is provided for solving the problems.

By replacing the Si-based power device with the SiC MOSFET, the voltage and current levels of the power circuit can be effectively improved, and meanwhile, the switching loss can be reduced due to the higher switching speed of the power circuit, and the dynamic control performance of the driver is improved. However, due to the high-speed switching behavior of the SiC MOSFET, bridge arm crosstalk and high-frequency electromagnetic interference are introduced to the driving circuit, and after the switching frequency is increased, the proportion of dead time in the whole period is increased, which may increase the voltage-current waveform distortion of the motor and affect the performance of the motor, and meanwhile, the high-speed switching requires a control circuit with higher dynamic response capability, so the motor driver needs to be optimized for the characteristics of the SiC MOSFET. And the digital and intelligent design idea can effectively solve the problems caused by the SiC MOSFET and realize the optimal design of the whole motor driver system.

In the design, the optimization design of the power driving unit is an important part, and how to realize data interaction between the power driving unit and the digital information processing unit, how to realize interference resistance of long-distance transmission communication between the information processing platform and the power driving unit under the long-distance condition that the distance between the information processing platform and the power driving unit is 5-10 meters, how to perform real-time adaptive optimization on driving parameters under different load conditions, and how to protect a power circuit as soon as possible and as safely as possible after a fault is an important research content.

Disclosure of Invention

The invention aims to provide a digital intelligent motor driver and a driving method aiming at the application scene of a three-phase full-bridge motor driver based on SiC MOSFET, and provides an effective solution for solving the problems of SiC MOSFET intelligent driving, data interaction anti-interference between a digital circuit and a power driving circuit, bridge arm crosstalk, dead time self-adaptive optimization, overcurrent and overvoltage protection of the power driver, power supply of a motor Hall and a position sensor and the like.

The motor driver has the functions of magnetic coupling isolation, secondary power supply transformation, Hall phase-changing control, overvoltage discharge inhibition, overcurrent current-limiting protection, short-circuit soft turn-off protection, dead zone time self-adaptive optimization, intelligent drive parameter adjustment, temperature sampling, current sampling and the like, CAN realize the drive control of a steering engine according to a differential PWM signal and a direction signal transmitted by a digital information processing platform, CAN inhibit the discharge of overvoltage surge caused by back electromotive force in the operation process of the steering engine, CAN limit the working current of the steering engine, CAN timely and safely turn off a power circuit in case of short-circuit fault, CAN adaptively adjust the dead zone time according to the current of a power loop, CAN automatically adjust the drive parameters according to the load condition, CAN feed back the internal temperature and current of the steering engine driver in real time through a differential bus, and CAN supply power to a CAN interface feedback position sensor and a motor Hall, and completing the transfer of information interaction between the feedback position sensor and the information processing platform.

In order to achieve the purpose, the invention adopts the following technical scheme. In a first aspect, the invention provides a three-phase full-bridge digital intelligent motor driver based on SiC MOSFETs, which mainly comprises a power board, a conditioning board and a structural body, and has no built-in software. Comprises a power board, a conditioning board and a structural body; the power board adopts an aluminum-based circuit board for realizing the functions of electric energy conversion, power driving, energy release and current sampling, and the aluminum-based circuit board is fixedly connected with a heat dissipation structure body by utilizing the advantage of good heat dissipation of the aluminum-based circuit board, so that good heat dissipation of the power driver is realized; the conditioning board is used for realizing the functions of interface signal processing, digital signal conversion, state monitoring and fault protection; the structure body is mainly used for fixedly connecting the power plate and the conditioning plate and providing a good heat dissipation carrier for the power device.

Furthermore, the power board adopts an aluminum-based circuit board, is mainly used for realizing functions of electric energy conversion, power driving, energy discharge, current sampling and the like, comprises a backflow prevention circuit, a discharge circuit, a power driving circuit, a power bridge circuit, an overcurrent protection circuit and a current isolation sampling circuit part, and utilizes the advantage of good heat dissipation of the aluminum-based circuit board to fixedly connect the aluminum-based circuit board with a heat dissipation structure body so as to realize good heat dissipation of the power driver. The conditioning board adopts an FR4 epoxy resin board, is used for realizing functions of interface signal processing, digital signal conversion, state monitoring, fault protection and the like, and mainly comprises a signal processing circuit, a differential interface circuit, a magnetic isolation interface circuit, an isolation power supply conversion circuit, a secondary power supply conversion circuit, a Hall interface circuit, a Hall phase conversion logic conversion circuit, a current sampling conversion circuit and a temperature sampling circuit. The structure body is mainly used for fixedly connecting the power plate and the conditioning plate and providing a good heat dissipation carrier for the power device.

The backflow preventing circuit is designed independently aiming at the power circuit and the control circuit, a power diode with 1200V withstand voltage and 120A rated overcurrent capacity is selected as a power circuit part and is connected in series into a power supply positive line of the power driver, and the backflow preventing circuit is used for preventing the current of a power bus VP from flowing backwards to the input end of a power supply when a motor is braked; the control circuit part selects a power diode with the voltage resistance of 250V and the rated overcurrent capacity of 6A, and the power diode is connected in series with a power source positive line of the power driver and used for preventing the current of the control bus VK from flowing back to a power supply input end;

the leakage circuit adopts PMOS as a power control device and adopts a power resistor as a dissipation load, when the voltage of the backward stage of the backflow-preventing power diode is more than 3V greater than the voltage of the forward stage of the diode, the PMOS device is conducted, the current on the power bus VP is leaked through the resistor, and further rise of the bus voltage is avoided, wherein the leakage resistor adopts an external mode.

The power driving circuit adopts BM6104-FV as a driving chip, and the chip calculates the output PWM signal according to the Hall commutation logic circuit, amplifies the control signal and outputs the gate driving signal for the three-phase bridge circuit. BM6104-FV is integrated with a short circuit protection function and a power embedded output function. The short-circuit protection function can detect the drain-source current of the SiC MOSFET, soft turn-off can be carried out through a large-resistance loop PROOUT when overcurrent occurs, if the current returns to be normal in the buffer time, the subsequent driving chip can return to work normally, if the overcurrent is detected after the buffer time, short circuit is judged, and forced turn-off is carried out. The soft turn-off circuit can limit overcurrent in time on one hand, and also reserve buffer on the other hand, so that the situation that the power device and even the whole driver are broken down by limit peak voltage generated by overhigh change rate of transient current due to instant turn-off of an overcurrent power loop is avoided. The active clamping position output function can be realized by opening the active Miller clamping position MOSFET after the power device is switched off according to a time sequence in the normal work of the driving circuit, absorbing interference voltage generated on the driving circuit by the high-frequency switch and bridge arm crosstalk through the Miller capacitor, and simultaneously switching off the active Miller clamping position MOSFET before the power device is switched on, and switching off the connection between the Miller capacitor and the gate source electrode, thereby avoiding influencing the high-speed switch of the SiC MOSFET.

The three-phase power bridge circuit is formed by 3 SiC MOSFET half-bridge power modules with withstand voltage of not less than 1200V and overcurrent capacity of not less than 400A in a bridge connection mode, and a nonpolar capacitor with a capacitance value of not less than 100uF and withstand voltage of not less than 1200V is connected in parallel on a bus of the bridge circuit.

The over-current protection circuit determines drain-source voltage corresponding to over-current by adjusting the value of a divider resistor by utilizing the output characteristic of the SiC MOSFET and combining a desaturation detection circuit built in the power driving chip BM6104-FV, and the magnitude of the current-limiting current can be determined by the load characteristic of the SiC MOSFET because the desaturation voltage and the power current have a corresponding relation, and the design value in the example case is 120A.

The current isolation sampling circuit adopts an ACS712 isolation current sampling chip to sample current input by a power supply, and the current is modulated into PWM waves through a PWM modulation circuit and output through a differential interface circuit, so that the current isolation sampling circuit is used for monitoring the current in real time by a digital processing platform.

The main control chip of the signal processing circuit is controlled by a DSP (digital signal processor), receives a current sampling signal, a temperature sampling signal and an instruction signal which are sent by a differential circuit and are in a PWM (pulse-width modulation) form, and obtains a corresponding PWM control signal and an F/R (frequency/direction) signal to the driving circuit through operation. Because the switching characteristic of the SiC MOSFET has a large relationship with the magnitude of the load current, the switching time may change greatly under different currents, and if a general driving manner with a fixed dead zone ratio is adopted, the dead zone time needs to be designed according to the maximum switching time, and when the load current changes, the dead zone time has an excessively large ratio under a high switching frequency, which may affect the magnitude of the harmonic of the motor driver current and the working performance of the motor. Therefore, the self-adaptive dead time driving technology based on the SiC MOSFET characteristics is different from a general driving mode in that an innovative dead time self-adaptive control mode is adopted, the dead time is linked with the sampling current, the dead time is dynamically controlled according to the load, the advantage of the high switching speed of the SiC MOSFET is utilized to the maximum extent, and the influence of the SiC MOSFET on the motor performance is reduced.

The differential interface circuit adopts AM26LS31 and AM26LS32 as differential interface chips, and the device is compatible with an RS422 interface level form, wherein AM26LS31 is used for sending PWM form current sampling signals and PWM form temperature sampling information and converting TTL level signals into RS422A differential signals. The AM26LS32 is used for receiving the differential steering engine control PWM signal and the FR direction control signal and converting the RS422A differential signal into a TTL signal.

The magnetic isolation switching circuit adopts an ADUM1401 device which is provided with three receiving channels and 1 sending channel and can receive a steering control PWM signal and an FR direction signal transmitted by a differential interface circuit.

The isolation power supply conversion circuit is used for converting a 12V voltage signal converted by the secondary power supply conversion circuit into a 5V isolation voltage signal for supplying power to the magnetic isolation conversion circuit, the differential interface circuit and the feedback position sensor.

The secondary power supply conversion circuit is used for converting the voltage of a power bus into a 12V control power supply, has the power output capacity not less than 5W, supplies power for the power driver and the Hall sensor, and converts a non-isolated 5V signal through the LDO to supply power for the power end of the magnetic isolation chip.

The Hall interface circuit is used for receiving a Hall signal of the motor, filtering is carried out by adopting an RC filter circuit, a Zener diode is used for protecting a port, and the input end of the Hall interface circuit pulls up a 10k ohm resistor to the Hall power supply.

The Hall commutation logic conversion circuit carries out logic operation according to the Hall signal, the PWM signal and the direction signal, and outputs 6 paths of PWM control signals according to a limited unipolar driving mode.

The current sampling conversion circuit converts the voltage signal output by the current sampling circuit into 2KHz PWM wave and outputs the PWM wave to the differential interface circuit.

The temperature sampling circuit adopts a PWM interface form temperature sensor which adopts isolated 5V power supply, and the temperature sampling range is-55-150 ℃. And the temperature signal output by the PWM is output after differential conversion.

In a second aspect, the invention provides a drive method of a digital intelligent three-phase full-bridge motor driver based on a SiC MOSFET, the drive method mainly outputs a direction signal and a PWM drive signal according to a certain logic sequence according to a position feedback signal, a temperature feedback signal, and a current sampling signal of a position sensor, and the specific steps are as follows:

step one, after an input power supply is powered on, an information processing platform reads a rudder feedback position signal, and within 50ms of power-on, a PWM driving signal needs to be kept at a low level. After 50ms, the PWM signal can be output according to the steering control requirement.

Step two, if the steering engine needs to rotate in the forward direction, the FR signal outputs a high level; and if the steering engine needs to rotate in the negative direction, the FR signal outputs a low level. The output duty ratio of the steering engine is determined by the duty ratio of a PWM signal, the carrier period of the PWM signal can be configured to be (2 k-20 kHz) in a configurable interval through an information processing platform, and the duty ratio range is (0-100%). In the steering engine control process, the information processing platform interprets steering engine feedback position information, an overcurrent protection signal, a temperature signal and a current sampling signal in real time, diagnoses the steering engine working state through the signals, adjusts the duty ratio and dead time of a PWM signal in real time, and outputs a corresponding steering control PWM signal and a corresponding direction signal.

The above description is only a preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, and any simple changes or equivalent substitutions of the technical solutions that can be made obvious by those skilled in the art within the technical scope of the present invention are within the scope of the present invention.

Compared with the prior art, the invention has the following advantages:

1) the motor driver receives RS422 differential type steering control PWM instructions and direction signals and outputs PWM type current signals and temperature sampling signals through RS422 interface levels in real time, the signals are isolated from a primary power supply through a magnetic isolation technology, the interfaces are designed to be anti-interference, the transmission distance can reach 10 meters, and the motor driver has good anti-interference performance;

2) this motor driver is to unmanned aerial vehicle, aircraft platform application occasion design such as spacecraft, possess motor power drive function, possess the excessive pressure simultaneously, overflow, undervoltage protection and prevent flowing backward the function, and at the rated current power driving capability of 40A in 18 ~ 400V voltage range, the withstand voltage of transient state is not less than 1200V, the transient current ability is not less than 120A, temperature and overflow state telemetering measurement output interface have, the operating voltage scope is wide, overcurrent ability is strong, the integrated level is high, excellent performance.

3) The motor driver is designed aiming at the output characteristic and the switch characteristic of the SiC MOSFET, and has the functions of self-adaptive dead time adjustment, intelligent driving and soft turn-off, and the active embedded position anti-crosstalk function can ensure the effective realization of high power and high frequency performance of the SiC MOSFET.

4) The motor driver can supply power for the position sensor and the Hall sensor, signal integration of the motor electrical interface and the position sensor electrical interface is achieved, the interface form is simple, and topological connection is simplified.

Drawings

The invention will be further explained with reference to the drawings and examples.

Fig. 1 is a layout diagram of a three-phase full-bridge digital intelligent driver structure and interface based on SiC MOSFETs according to an embodiment of the present invention.

Fig. 2 is a functional block diagram of a three-phase full-bridge digital intelligent driver based on SiC MOSFETs according to an embodiment of the present invention.

Fig. 3 is a schematic block diagram of an isolated differential conversion, temperature and current sampling, and power conversion circuit according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of a bleed circuit in accordance with an embodiment of the present invention.

Fig. 5 is a schematic diagram of an over-current sampling and protection circuit according to an embodiment of the present invention.

FIG. 6 is a schematic diagram of a power-on latch-resistant circuit according to an embodiment of the present invention.

Fig. 7 is a block diagram of a power bridge circuit according to an embodiment of the invention.

Fig. 8 is a diagram of a three-phase full-bridge digital intelligent motor driver based on SiC MOSFETs.

Detailed Description

Embodiments of the present invention are described below with reference to the accompanying drawings:

referring to fig. 1, a three-phase full-bridge digital intelligent driver structure and an interface layout based on a SiC MOSFET, a motor driver is composed of two circuit boards of a power board and a conditioning board and a shell, wherein the power board is an aluminum substrate, the back of the power board is fixedly connected with a heat dissipation structure body, and the motor driver is provided with a mounting hole which can be mechanically assembled with a steering engine structure body. The conditioning board is an FR4 epoxy resin board, and is connected with the power board through a connector between the boards to realize signal interconnection. The driver is provided with 3 external interfaces, namely a power supply interface, a communication interface and a steering engine interface, which are respectively arranged at two sides of the driver, wherein the power supply interface is separated from the communication interface, so that the electromagnetic interference of the power supply interface to the communication interface is avoided; the steering engine interface adopts the form of throwing out an external cable interface and is connected with the motor, the feedback position sensor and the bleeder resistor, wherein a position sensor signal wire adopts a shielding cable coating form, and the electromagnetic interference caused by a power signal is avoided. The driver is simple in structural form, simple in external interface and suitable for application scenes such as unmanned aerial vehicles and spacecrafts.

Referring to fig. 2, a functional block diagram of a three-phase full-bridge digital intelligent driver based on a SiC MOSFET is provided, the digital intelligent driver adopts a communication interface design scheme based on a differential level interface, and has comprehensive functions of backflow prevention, motor driving, an energy release circuit, hall commutation, overcurrent protection, temperature acquisition, current acquisition, secondary power conversion, hall and position sensor power supply, magnetic coupling isolation and the like, and can complete drive control of one steering engine. The information processing platform acquires a position sensor signal, a temperature signal and a current signal output by the driver, outputs a steering engine PWM signal and a direction signal according to a control algorithm and drives a steering engine to move; the driver can monitor the current and temperature conditions in real time in the process, and when the load current is greater than the current limiting value of the driver, the overcurrent protection circuit can work, so that the driver can safely operate in the maximum current limiting output mode. In the work engineering, for the bus voltage fluctuation caused by motor phase change and steering engine braking, the bleeder circuit can judge the bus voltage fluctuation situation in real time and control the bus voltage to be maintained in a safe working voltage range through the bleeder resistor. The present invention will be further explained with respect to several important circuit components of the driver.

Referring to fig. 3, a functional block diagram of an isolation differential conversion, temperature and current sampling and power conversion circuit, a digital intelligent driver adopts a magnetic isolation differential interface design scheme, a secondary power conversion circuit converts a power input into a 12V control power, and the control power is converted into an isolation 5V power and a non-isolation 5V power by a magnetic isolation conversion chip DCR021205U and an LDO. The isolation 5V power supply supplies power to the isolation conversion circuit and the position sensor, and the non-isolation 5V power supply supplies power to the power end of the magnetic isolation chip. The temperature sampling chip adopts a PWM interface type sensor and adopts isolated 5V power supply, and the temperature measuring range is-55-150 ℃. The current sampling chip adopts an ACS712 series magnetic isolation sampling chip, adopts isolation 5V power supply, and is converted into a PWM interface form through a PWM conversion chip. And aiming at two input signals (steering control PWM and steering control FR signals) and two output signals (temperature TMP and current I) of the driver, a differential receiving and sending chip is adopted to complete the conversion between the RS422 level and the TTL level. And the input port is connected with a 120 omega matching resistor, and all the differential interfaces are connected with bidirectional antistatic diodes in parallel for protection. For the position sensor, a CAN bus signal of the position sensor is output by the position sensor, the driver only conducts switching and passing, and is connected with an anti-static diode in parallel at a port of the driver for interface protection, the driver adopts isolation 5V to directly supply power for the position sensor, and the problem that the power supply voltage of the sensor is low due to line voltage drop when an information processing platform is used for long-distance power supply is solved. The driver and the information processing platform adopt a differential bus communication mode, the transmission distance can reach 10 meters, the anti-interference performance is good, the signal transmission quality is high, and the reliability and the stability of the system are favorably improved.

Referring to fig. 4, a schematic diagram of a bleeder circuit of a digital intelligent driver, in which a PMOS device with a 1200V/10A specification is used as a switching device, voltages before and after a backward flow prevention diode are used as an interpretation threshold, and when a power bus voltage is higher than a previous stage voltage by 3V, the bleeder circuit starts to operate. In addition, the power bus is connected with the 1200V transient suppression diode in parallel, and when the bus instantaneous voltage is higher than 1200V, the transient suppression diode works to absorb the transient voltage, so that the power bridge circuit is protected.

Referring to fig. 5, a schematic diagram of an overcurrent sampling and protection circuit, a digitized intelligent driver overcurrent detection circuit detects overcurrent in a saturation detection mode, because the load current corresponds to the drain-source voltage in the output characteristic, the current value can be indirectly measured by detecting the drain-source voltage value, after the built-in SCP circuit of the driving chip detects the overcurrent, the soft cut-off can be carried out through a PROOUT pin, because the resistance value of the series-connected turn-off resistor of the PROOUT pin is larger, the soft turn-off process is slower than the normal turn-off process during overcurrent, the rapid current change in the power loop caused by the over-fast turn-off is avoided, the generation of a large induced voltage across the parasitic inductance of the power loop results in power device or driver breakdown, meanwhile, the drive chip is internally provided with buffer time, and when the overcurrent time exceeds the buffer time, the drive chip can be directly switched to hard turn-off, so that the power device or the driver is prevented from being burnt by large current for a long time.

Referring to fig. 6, a circuit schematic diagram of the active embedded position anti-crosstalk circuit is shown, in the digital intelligent driver, since a SiC MOSFET device is used as a power device, a very short switching time of the digital intelligent driver causes a rapid change of a power circuit current in a switching process, an induced electromotive force is generated on a parasitic inductance of the power circuit, and the electromotive force is transmitted through a gate capacitor of the SiC MOSFET, and affects a gate-source voltage of the SiC MOSFET, thereby causing a false turn-on and a false turn-off, and even causing a bridge arm to be directly connected. Therefore, the problem of bridge arm crosstalk caused by the high-speed switch of the SiC MOSFET needs to be suppressed by adopting the active embedded position circuit, the driving chip adopted by the digital intelligent driver is embedded with the active embedded position driving function, the auxiliary MOSFET switch of the active Miller embedded position circuit can be automatically driven according to the time sequence of the bridge arm switch, the Miller capacitor is incorporated between the gate and the source in the turn-off process of the power switch to suppress crosstalk voltage, and the driving circuit is protected from interference.

Referring to fig. 7, a power bridge circuit block diagram, a digital intelligent driver realizes final energy conversion through a three-phase bridge circuit.

Referring to table 1, table 1 is a hall commutation solution and protection output logic table according to an embodiment of the present invention.

The circuit part adopts a hardware logic design scheme based on a gate circuit, outputs PWM signals driven by the steering engine according to the logic relation in the logic table, and realizes the drive control of the steering engine. The logic table is based on limited unipolar brushless motor driving and upper bridge PWM modulation modes, and logic is conducted pairwise.

Fig. 8 is a diagram of a three-phase full-bridge digital intelligent motor driver based on SiC MOSFETs.