New energy vehicle discharge method for high voltage busbar

Abstract

The application discloses a method for discharging high voltage of a bus bar in a new energy vehicle, which includes the following steps: Step 1: When the vehicle controller issues a discharge command, the battery management system disconnects the high voltage battery from the inverter. In the second step, the motor controller controls the six power switching devices in the inverter, so that the direct-axis current of the permanent magnet synchronous motor decreases with the decrease of the bus voltage, and the quadrature-axis current is always zero, so that the bus capacitor Energy is consumed inside the permanent magnet synchronous motor. Step 3: When the bus voltage drops to within the safe voltage range within the specified time, the motor controller makes the three-phase active short circuit of the permanent magnet synchronous motor, or makes the direct axis current and the quadrature axis current of the permanent magnet synchronous motor equal to zero. Otherwise, the motor controller makes the three-phase active short circuit of the permanent magnet synchronous motor, and feeds back the discharge overtime fault to the vehicle controller. The application discharges quickly, is safe and reliable, and the bus voltage will not rise again after the discharge is completed.

Description

technical field [0001] The present application relates to a method for safely discharging high voltage of a busbar by a new energy vehicle. Background technique [0002] see figure 1 , The motor drive system of new energy vehicles (electric vehicles, hybrid vehicles, etc.) mainly includes high-voltage batteries, inverters, and permanent magnet synchronous motors. A high-voltage battery refers to a battery pack with an output DC voltage higher than 100V, which is controlled by a battery management system (BMS). The inverter is used to convert the DC output from the high-voltage battery into AC to drive the permanent magnet synchronous motor. The motor controller is used to control the turn-on or turn-off of each power switching device in the inverter, and to control the permanent magnet synchronous motor. Common control strategies of motor controllers for permanent magnet synchronous motors include PWM (pulse width modulation), SPWM (sine wave pulse width modulation), SVPW...

AI Technical Summary

Problems solved by technology

However, if the permanent magnet synchronous motor is pulled up again at high speed (such as being dragged by the engine in a collision condition), the energy of the permanent magnet synchronous motor will be fed back to the bus capacitor, causing the bus voltage to cause high voltage risk again

see image 3 , the existing Freewheel mode is used as a safe mode, and the safe mode is entered after the bus voltage drops below the safe voltage range of 60V. However, the energy of the permanent magnet synchronous motor is fed back to the bus capacitor, causing the bus voltage to rise again, causing high voltage risk

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