Motor controller active discharge system and control method

Abstract

The invention discloses a motor controller active discharge system and a control method. The system comprises a film capacitor arranged on a bus, an IGBT circuit, a motor, an IGBT temperature samplingcircuit and a driving circuit which are connected with the IGBT circuit, a bus voltage sampling circuit connected with the film capacitor, and a motor temperature sampling circuit, a motor rotating speed sampling circuit and a driving circuit which are connected with the motor, wherein the driving circuit is with a power supply circuit. When the system finds that a motor winding or an IGBT modulegoes wrong, the system can select discharge paths respectively, the risk of active discharge IGBT failure is reduced, and a discharge speed problem is solved.

Description

technical field [0001] The invention relates to a technology in the field of motor drive control, in particular to an active discharge system and control method for a motor controller. Background technique [0002] In order to ensure personal safety, the motor controller needs to have an active discharge function. The current active discharge technology mainly focuses on the following three discharge methods: 1. Discharge through the motor winding and add D-axis current. The discharge time is fast, but it will bring unexpected Torque affects the driving experience; 2. By adding an external discharge circuit, the risk is small and reliable, but it will increase the hardware cost; 3. The bridge wall is directly discharged, which is low in cost and fast in discharge speed, but the instantaneous current is large. Due to the high voltage circuit There is stray inductance on the ground, which leads to a large voltage stress when the IGBT (insulated gate bipolar transistor) is turn...

AI Technical Summary

Problems solved by technology

[0002] In order to ensure personal safety, the motor controller needs to have an active discharge function. The current active discharge technology mainly focuses on the following three discharge methods: 1. Discharge through the motor winding and add D-axis current. The discharge time is fast, but it will bring unexpected Torque affects the driving experience; 2. By adding an external discharge circuit, the risk is small and reliable, but it will increase the hardware cost; 3. The bridge wall is directly discharged, which is low in cost and fast in discharge speed, but the instantaneous current is large. Due to the high voltage circuit There is stray inductance on the ground, which leads to a large voltage stress when the IGBT (insulated gate bipolar transistor) is turned off. The test object is a 750V / 820A IGBT module. When the bus voltage is 520V, a single pulse short-circuit test is carried out, and the actual measurement of channel 3 The data Vce rushes to 716V, and as the bus voltage rises, the short-circuit current rises, the shutdown speed is accelerated, and the peak voltage will increase further until it exceeds the limit voltage of 750V

In actual working conditions, when the motor is running at high speed and the main relay of the power battery is disengaged, the film capacitor will be charged to the maximum back EMF by the motor feed. At this time, direct short-circuit discharge will cause damage to the IGBT. even breakdown

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