⑴ Transformerless UPSTransformerless UPS is a high-frequency UPS without isolation function. It can completely use no transformer. Its typical circuit is shown in Figure 1. The circuit is composed of a three-phase IGBT Boost SPWM high-frequency switching rectifier and a three-phase half-bridge IGBTSPWM high-frequency inverter through a battery (consisting of 67 batteries in series, with…
