This dissertation introduces the principle of the on-line UPS, and the SPWM technology for the UPS inverter is also discussed. The effect of blanking time on the output voltage in PWM inverters and the methods to eliminate it is described. 本文首先介绍在线式UPS的基本原理以及逆变器的SPWM调压方法,研究死区对逆变器输出电压的影响及其补偿方法。