A high performance DSP voltage controller with PWM synchronization for parallel operation of UPS systems

In order to achieve the good load sharing performance in parallel operation of a three-phase UPS inverter system, this paper describes a control method with an inverter current feed-forward compensator including design criteria for choosing the feed-forward gain. Especially, this paper discussed about the harmonic circulating current due to PWM non-synchronization which disturbs the precision of load sharing and creates a noise problem in parallel operation of inverter system. The proposed control schemes and the related algorithm is very simple to be implemented using DSP, and also it satisfy the precision of load sharing in parallel operation of inverters. Experimental results from a 50kVA three-phase inverter using DSP (TMS320F2812) show the feasibility and effectiveness of the proposed control schemes.