New techniques in PWM and resonant converters

In this thesis, a new Zero Voltage Switching (ZVS) technique for Buck, Boost and Buck-Boost converters using coupled inductors is proposed. The main inductor current is continuous with small ripple, which allows high output power and small filter parameters. At the same time, ZVS conditions are achieved for switches over a wide load range. Prototypes have been built. Experimental results are presented to verify the analysis.; Also, a new ZVS phase-shifted PWM DC/DC converter is proposed for transformer isolated applications. A half-bridge DC/AC inverter is cascaded with a push-pull type synchronous rectifier through an inductive link. Switching of the inverter is phase-shifted with respect to the synchronous rectifier. All switches have ZVS conditions. Experimental results are presented.; A novel envelope response technique is proposed to analyze resonant DC/AC converters. For a given resonant converter, its orthogonal counterpart is constructed. By combining two circuits into one complex circuit, envelope response is obtained. The proposed method can predict the large signal transitions of resonant DC/AC converters. The results are verified by PSPICE simulation.; Orthogonal circuit synthesis is proposed to analyze resonant DC/AC converters and resonant DC/DC converters. For a given resonant tank, its complex resonant tank is constructed. By applying Kirchhoff's Voltage Law (KVL) and Kirchhoff's Current Law (KCL) to the complex circuit, complex differential equations are derived. By separating real and imaginary parts of the complex differential equations, state equations for the resonant tank are obtained. In the case of resonant DC/DC converters, other state equations are derived from rectifier stages. These state equations contain only low frequency state variables and can predict large signal transitions of the resonant converter. By perturbing these equations around the DC operating point, the small signal model is derived. The derived transfer functions are verified by SIMPLIS simulation.; Finally, d-q models for resonant DC/AC converters and resonant DC/DC converters are developed. For a given resonant converter, its corresponding complex resonant tank is first constructed. The complex resonant tank is then expressed in d-q form. By removing high frequency components, the low frequency d-q model for the resonant converter is obtained. This allows large signal transitions to be predicted. By perturbing the d-q model, the small signal equivalent circuit model for the resonant converter is derived. The derived transfer functions are verified by SIMPLIS simulation.