Constant-frequency resonant power processors

Abstract

Two constant-frequency resonant power processors are discussed. The parallel resonant converter(PRC) with a controlled output rectifier can provide both forward and reverse power flow. A new control parameter — "θ-angle" is proposed for achieving output regulation and bidirectional power flow of the PRC. The θ-angle, measured as the displacement angle between the firing of the inverter switches and the firing of their corresponding output rectifier switches, provides a control-to-output characteristic independent of load variations and is very easy to implement. Unified closed-form expressions for the steady-state operating conditions are derived. Circuit performances are analyzed through closed-form solutions. Similar analyses are performed for a phase-controlled dual-inverter resonant converter. The feasibility of generating a regulated high-frequency AC bus employing this circuit is investigated. A controlled rectifier and LC filter type of load is used for the circuit to demonstrate the complex interactions between the inverters and the load and the effect of load power factor on the quality of the ac bus voltage. Desired operating regions for input, output, and various control parameters are analytically defined through closed-form solutions such that good quality ac bus voltage can be achieved.