Suppression method of rising DC voltage for the halt sequence of an inverter in the motor regeneration

In the power conversion system of electric vehicles, the inverter is shut down when the system fails in the cause of a drastic load change or other protection reasons. However, in the case if the inverter is shut down in regeneration mode, the DC link capacitor voltage is increased dramatically, which will potentially break the switching devices. In this paper, the authors propose a halt method to overcome the over voltage and over current problems in the case of system failure during the regeneration. The proposed method consists of two phases, in the phase I, the DC link capacitor voltage is controlled by charge and discharge switching patterns based on space vector of the inverter. Then, the phase II performs the short circuit operation in order to avoid the regenerating current from the motor flows into the DC link capacitor. The experimental results demonstrate that the DC link capacitor voltage is 80% lesser comparing to the conventional method. Furthermore, the circulating current can be suppressed by 46% from the proposed method.