A new class of current-controlled suppressed-link AC to AC frequency changers

Static frequency changers (SFCs) typically use a rectifier-inverter combination with a passive LC filter as the intermediate DC link. This class of SFCs does not allow sustained regeneration and requires a bulky DC filter. A recently proposed alternative, based on the synchronous energy transfer principles, has successfully solved the problems of power regeneration, but still requires a DC side filter. Moreover, it is very susceptible to input AC line unbalances. A class of compact regenerative SFCs, which do not require a DC filter, are insensitive to input unbalances, and have a very rugged power and control circuit structure. PWM pattern generation on the inverter side is based on output current control. Design and implementation considerations are discussed. Simulation and experimental results confirm the feasibility and predicted performance of the proposed class of converter circuits