The digitalization of UPS power supply

The advent of power MOSFET and IGBT has opened up a brilliant road for UPS, ushering UPS technology into a new era - the fully digital era.

First, the input part of the UPS eliminates the power frequency transformer used for isolation from the mains or the autotransformer used for voltage reduction, and adopts SPWM technology to achieve high-frequency rectification (AC/DC). On the one hand, it reduces the size of the DC side filter, improves the DC side regulation performance, and increases the allowable variation range of the mains voltage; on the other hand, the control technology uses a digital signal processor DSP (Digital Signal Processor) to control the input current to make it sinusoidal and in phase with the mains voltage, thereby achieving a high UPS input power factor (PF≈1), eliminating harmonic "pollution" to the mains, achieving environmental protection, greatly reducing reactive power loss, and significantly reducing operating costs.

Secondly, the power frequency transformer in the UPS inverter is eliminated, and a high-frequency transformer is used to isolate the UPS from the mains, while the output stage of the UPS uses SPWM conversion (direct inversion without a transformer) to output power frequency voltage. The operating frequency of the power MOSFET or IGBT in the inverter is above 20kHz, so the output filter is small and simple, and the output sine wave is very smooth.

The battery pack inside the UPS is charged by high-frequency conversion and voltage reduction ( DC/ DC). When the city power fails, the UPS switches to powering the inverter by the battery, which also adopts high-frequency conversion and voltage reduction (DC/DC).

The use of sine wave direct feedback technology in the inverter control circuit makes it highly regulated, far superior to the traditional analog feedback technology. Coupled with a small output filter and SPWM modulation above 20kHz, the UPS dynamic response characteristics are very good. The use of high-performance overcurrent protection technology in the inverter protection circuit makes the inverter not only have a strong overload capacity, allowing 100% load imbalance (referring to three-phase inverters), but also have strong self-protection. It is also under the above conditions that the traditional inverter output transformer is abandoned, which is not only low in noise but also high in efficiency.

The fully digital UPS is a new generation of UPS. In addition to its high quality, high reliability, high index, and multi-function characteristics, it also meets today's energy-saving and environmental protection requirements. Therefore, it is a UPS that can not only meet today's needs, but also adapt to future development needs.