Transformerless Technology

Advantages:

Improved efficiency
Higher input power factor
Lower input current harmonic distortion (THDi)
Reduced operating costs
Reduced physical size and weight
Lower audible noise
Enhanced battery life
Reduced capital cost

The traditional transformer-based UPS technology has achieved its limits in terms of further technological improvement. With the exception of minor hardware and software corrections the transformer-based UPS technology does not allow additional technological developments that would yield true benefits. The bulky integrated output transformer, the obsolete controlled SCR input rectifier stage and the traditional PWM-inverter-switching technology are the limiting factors.

The obvious step forward in qualitative development of the UPS technology was to design a new three-phase UPS technology without the output transformer, with a non-controlled diode rectifier stage followed by an advanced booster stage and a new energy-saving inverter switching technology (see Fig. 1).