ESO-based pure electric vehicle bus capacitor discharge system and method

Abstract

The invention discloses an ESO-based pure electric vehicle bus capacitor discharging system and method. The system mainly comprises a controller, a power battery, a circuit breaker, a DC / DC converter, a bus capacitor, an inverter and a three-phase permanent magnet synchronous motor. According to the method, a permanent magnet synchronous motor winding is used as an energy bleeder. According to the method, a discharge process is divided into three stages: firstly, a fixed current is applied to a d axis in a weak magnetic voltage reduction stage, so that a bus voltage is rapidly reduced to a safe voltage, and the system enters a constant voltage stage; in the constant-voltage stage, ESO is adopted to observe the total loss in the system discharge stage, feedforward compensation is carried out, the bus voltage is stabilized at the safe voltage, and when the rotating speed is reduced to be lower than the safe rotating speed, the free deceleration stage is started, and d-axis and q-axis currents are gradually reduced to 0; through the above three stages, safe and rapid discharge of the bus capacitor of a pure electric vehicle driving system in emergency is realized, the surge phenomenon of the bus voltage is avoided, and the method has the advantages of high robustness and high safety.

Description

Technical field[0001]The present invention relates to a busbar capacitance discharge method, in particular to an ESO-based pure electric vehicle bus capacitance discharge system and method.Background technique[0002]Since the permanent magnet synchronous motor has high power density, high efficiency and simple control, it has gained more and more extensive applications in pure electric vehicle power drivers. The electric vehicle drive system mainly includes a motor, a motor driver, and a motor controller, wherein the motor driver further includes a three-phase inverter, a bidirectional DC / DC power converter, a busbar capacitor, and a circuit breaker between the battery and the capacitance. The bus capacitance in the drive has the function of wave and power exchange; during the driving of electric vehicles, when encountered a burst (for example, a car accident), the drive's circuit breaker will quickly move, cut off the connection between the battery and the drive to prevent Seconda...

AI Technical Summary

Problems solved by technology

[0003] Generally, in an emergency, the electric vehicle permanent magnet synchronous motor driver will turn off the power tube to prevent other problems, but this will cause the energy in the bus capacitor to be unable to be released, maintaining the bus voltage at a dangerously high level

So there are currently three main discharge strategies, one is to add a discharge circuit between the bus capacitor and the battery, but this will increase the cost and volume of the drive; the second is to short-circuit the three-phase drive, so that the energy is consumed in the three-phase drive On the power device, but the discharge current is uncontrollable in this way, which will damage the power device of the three-phase driver; there is another method that uses the permanent magnet synchronous motor winding as a discharge resistor to dissipate energy on the winding. This method has simple structure and low cost. Advantages such as low voltage and high reliability, but there may be problems of bus voltage surge and slow discharge speed

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