Multi-level single phase boost rectifiers using coupled inductors

The number of voltage levels available in PWM voltage source converters can be increased by using a split-wound coupled inductor and interleaved PWM switching. This paper examines this technique using a multi-level 1-phase boost rectifier. Traditional interleaved boost rectifiers lower the high frequency input current ripple using current ripple cancellation. Alternatively, the proposed approach uses high frequency multi-level PWM voltage waveforms. The high frequency current ripple and parasitic DC currents are the only winding current components that produce magnetic flux in the coupled inductors. This contrasts with traditional interleaved boost rectifiers where the much larger AC supply input current produces flux in the magnetic core. This feature allows the physical size of the coupled inductors to be reduced, and their inductor value increased to provide improved protection against core saturation. Simulation and experimental results are used to illustrate the operation of the proposed converters. A design study is presented to illustrate that the proposed technique has much lower magnetic core losses, and is competitive in size to traditional techniques.