Comprehensive protection control method for controller drive system of electric automobile

Abstract

The invention provides a comprehensive protection control method for a controller drive system of an electric automobile, which relates to the field of power devices of new-energy automobiles and the control field of permanent-magnet motors. The control method comprises the following steps of: after obtaining a next periodic pulse modulation duty cycle of a drive power device by calculating, acquiring temperature and voltage signals by an over-temperature protection control module; calculating the maximum permissible average current standards of a generating line and a phase line by combiningtemperature external characteristic curves of a power component and an energy storage capacitor; inputting the maximum permissible average current standards of the generating line and the phase line to a generating line and the phase line maximum average current protection control module and adjusting an output duty cycle; after judging by an overvoltage and undervoltage protection control module, entering a PWM (Pulse Wavelength Modulation) output module; and judging whether to cut off PWM outputs cycle by cycle or permanently cut off by coordinating with a generating line and the phase linepeak current limit standard judgment module and a generating line and the phase line peak current overcurrent standard lock module. According to the comprehensive protection control method for the controller drive system of the electric automobile, the damage to the electric automobile arising from high current can be avoided.

Description

technical field [0001] The invention relates to the field of power devices of new energy vehicles and the field of control of permanent magnet motors, in particular to a comprehensive protection control method for a controller drive system of an electric vehicle. Background technique [0002] With the rapid development of new energy vehicle technology, the research and development focus of pure electric vehicle technology has gradually concentrated on the three technical fields of battery, motor and motor drive system. At present, the motors used in pure electric vehicles mainly include DC motors (DCM), induction motors (IM), permanent magnet synchronous motors (BLDC and PMSM) and switched reluctance motors (SRM). [0003] Different from traction systems used in other fields, in order for electric vehicles to meet the needs of climbing, parking and acceleration, the traction system should be able to provide a large enough peak torque. After comparison, the permanent magnet ...

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Problems solved by technology

[0005] Under the limitation of the national electric vehicle human body electric shock protection standard and the size of the electric vehicle itself, the pure electric passenger car, pure electric mini truck and other systems adopt a low-voltage high-power drive system. Generally, the voltage of the battery pack is less than or equal to 72 volts. The total power of the system is greater than 10 kilowatts, which means that the rated current used to drive the power FET in the drive system of the permanent magnet synchronous motor controller will be greater than 300 amperes at least, and the peak current generated when starting with load will be greater than 600 amperes , which means that in the permanent magnet synchronous motor controller drive system of low-voltage and high-power electric vehicles, the current stress on each bridge arm power tube in the three-phase six-bridge circuit is very large, due to the limitation of current electronic semiconductor technology At present, the parallel connection technology of power devices such as MOS or IGBT is generally used. Although this technology reduces the current stress of each bridge arm, it increases many unstable factors. The power device such as MOS or IGBT in a single bridge arm is affected The current stress will not be absolutely balanced, and the temperature rise of power devices with large current stress will inevitably be higher than the average temperature rise of the overall power device, thereby increasing the temperature rise of the overall drive circuit

And different from the motor drives used in industrial and civil fields, the operating conditions of electric vehicles are very complicated. In addition to frequent overloading and frequent starting, the test of intensified road surfaces, it also needs to experience the test of various harsh weather environments. The electronic components in the motor drive system In addition to the continuous vicious loss caused by high current and over-temperature conditions, the device will also encounter hidden dangers such as high temperature, humidity and water ingress. Since the three-phase stator winding of the permanent magnet synchronous motor is connected to the neutral point of the motor through the Y-type connection Yes, during the operation of the electric vehicle controller, the occurrence of any of the above situations will cause the controller to be affected by faults such as overcurrent, overvoltage, undervoltage, phase-to-phase short circuit, overtemperature, etc., which will inevitably cause motor control problems. Damage to electronic components in the drive system, including energy storage capacitors, power FETs and other important components, will cause fatal damage to the half-bridge parallel drive FETs of low-voltage high-power brushless motor drivers, resulting in batch MOS or IGBT and other power devices are damaged, seriously affecting the operation stability and maintainability of electric vehicles

However, the currently commonly used permanent magnet motor drive system protection control method is to adopt a closed-loop control method for the current by sampling the bus current and the phase line current through the microprocessor, which is limited to controlling the average current flowing in the power field effect tube to prevent it. Exceeding its own rated current index, it is impossible to fully consider other important performance parameters such as DC bus voltage, driving voltage, instantaneous peak current, and temperature to control the continuous loss of the motor drive system and realize its protection against some of the above fatal damage situations. prevention and comprehensive protection

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