Batteries are widely used in quite a few areas, including in the electric vehicles (EV). As the voltage of the batteries are ever-changing, which drops from a high value to a low value, kinds of regulators are utilized to keep the output voltage changing in an acceptable scope. However, the inverter output shaft voltage is a big threat to the motor connected with the inverter. In this paper, it is the main content to discuss how to use soft switching on some switches, furthermore, how to decrease the output shaft voltage on motor. A sort of improved CUK converter and a newly-advanced neutral pointed clamped (NPC) switching voltage source (SVS) circuit are integrated, whose aim is to realize the soft switching on switches and better output voltage in the simulation using the Pspice software. Finally, relative experiments have been made and corresponding samples have been produced.