The Journal of Engineering (Jan 2019)
Reliability study on DC-link capacitor in fault states of VSI in elective vehicle
Abstract
DC-input side of the inverter to balance input and output power, eliminate voltage fluctuation, and reduce the voltage spike in the input side. The reliability study on DC-link capacitor under fault state is critical to the safe operation of the whole driving system. This study builds the equivalent circuit of voltage source inverter (VSI) with space vector pulse width modulation (SVPWM) strategy and analyses the current characteristic of DC-link capacitance in normal operation state. The current characteristics of DC-link capacitor under main Insulation Gate Bipolar Transistor (IGBT) open-circuit fault states are analyzed and the characteristic differences from those in normal operation state are explored. Further, a fault identification method is developed. A simplified MATLAB model of EV driving system based on the VSI is established to simulate its time-domain characteristics and spectrum characteristics of DC-link capacitive current under normal operation and various fault conditions. The correctness of theoretical analysis and the effectiveness of fault identification is verified. The current spectrum characteristics of DC-link capacitance under normal operation condition are used to guide the optimal design of DC-link capacitor bank. Fault identification based on DC-link capacitor current characteristics is used to guide the fault-tolerant operation plan.
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