For automatic guided vehicles with dynamic wireless power transfer (DWPT), the vertical variation in the height of the pickup coil is inescapable due to load variations. It can cause changes in the system coil parameters (self-inductances and mutual inductance), further affecting the stability of the system output power. To realize a stable output of the DWPT system when the height of the pickup coil is variable, a parameter design method is proposed in this paper. A mathematical model of output power is established considering the vibrations of coil parameters. The influences of the compensation circuit on the output power and the input impedance are analyzed. The fluctuation of the output power is limited with the circuit parameter optimization. Finally, a 1-kW prototype is built to verify the effectiveness of the proposed approach. Experimental results indicate that within the gap range (20mm~40mm), the maximum fluctuation of the designed system output power is only 4.39% even if the self-inductances vary by 12.33uH and 27.9uH, respectively, and the mutual inductance changes by 1.45 times. Furthermore, the lowest efficiency of the system can reach 91.73%

dynamic wireless power transfer (DWPT),variable coils parameters,parameter design,stable output power