A phase-locked-loop synchronization scheme for parallel operation of modular power supplies

Operation of a power converter module that is synchronized to an external reference signal has been achieved using the proposed PLL circuit. The main features of the scheme detailed in this study include wide capture and lock ranges, fast transient response, and a variable-gain characteristic. The circuit corrects for the phase angle associated with the output filter and responds to step changes in the phase reference signal. The transient response of the system was calculated and verified experimentally. Thus, the closed-loop PLL synchronization circuit is more effective than the conventional method of providing timing pulses. In addition, the proposed PLL offers flexibility and frequency synchronization when phase detection is lost