Short circuit fault-tolerant LCC-S wireless power transfer system

Short circuit faults (SCF) in full bridge inverter result in more serious failures if not promptly resolved. In this paper, a fast short circuit fault diagnosis method is proposed for wireless power transmission networks with inductance-double capacitances-series compensation circuits. Each arm of the bridge is connected in series with a sampling resistor. When a MOSFET or an IGBT is short circuited, the sampling resistor voltage is much larger than before. Based on this, the system built in this paper can quickly stop the pulse of the other switch in the same bridge. Then, the full bridge converter is transformed into a half bridge converter, which causes the output voltage to drop by half. To obtain a constant voltage output, a BOOST + WPT structure is proposed. When there is no fault, the boost does not work. When a SCF occurs, the pulse of the short circuited MOSFET or IGBT is stopped and the boost starts to work with 50% duty cycle on the MOSFET to keep the output voltage unchanged. The effect on the efficiency and constant voltage output with a sampling resistor is studied. The short circuit current is analyzed for different circuit parameters, and the voltage change on the capacitance is analyzed. Taking the output voltage drop by less than 1% as the bottom line, the selection criterion of the sampling resistor should be that the load resistance value is 100 times greater than the sampling resistor value. Finally, the experimental results with the input voltage of 30 V verified the correctness of the theoretical analysis and the feasibility of the proposed method.