A pure electric vehicle bus capacitor discharge system and method based on ESO

Abstract

An ESO-based pure electric vehicle bus capacitor discharge system and method, the system mainly includes 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. This method uses the permanent magnet synchronous motor winding as an energy drain. This method divides the discharge process into three stages. First, in the field-weakening step-down stage, a fixed current is applied on the d-axis to rapidly drop the bus voltage to a safe voltage, and the system enters a constant voltage stage; in the constant voltage stage, ESO is used to control the system The total loss in the discharge stage is observed, and feed-forward compensation is performed to stabilize the bus voltage at a safe voltage. When the speed drops below the safe speed, it enters the free deceleration stage, and the d-axis and q-axis currents gradually decrease to 0; through the above three In the first stage, the safe and rapid discharge of the bus capacitor of the pure electric vehicle drive system is realized in an emergency, and the surge phenomenon of the bus voltage is avoided. It has strong robustness and high safety.

Description

technical field [0001] The invention relates to a bus capacitor discharge method, in particular to an ESO-based pure electric vehicle bus capacitor discharge system and method. Background technique [0002] Due to the high power density, high efficiency and simple control of permanent magnet synchronous motors, they have been more and more widely used in the power drive of pure electric vehicles. 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 bus capacitor, and a circuit breaker between the battery and the capacitor. The bus capacitor in the driver has the functions of smoothing and power exchange; during the driving process of the electric vehicle, in the event of an emergency (such as a car accident), the circuit breaker of the driver will act quickly to cut off the connection between the battery and the driver to pre...

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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