Quasi-resonant version of a new series-switching regulator

A new series switching regulator topology is proposed. It consists of a two-power stage pulse width modulated (PWM) power converter in constant-frequency quasiresonant version (CF-QR). This offers several advantages: high efficiency, reduced size and weight, low noise, low cost and high mean time between failure. Due to its power density the proposed topology is suitable in distributed power applications where galvanic isolation is not required. The transition from PWM to QR is easy to obtain by using the primary inductance of coupled inductors already present in the circuit as an element for the resonant circuit. The particular control technique used avoids overlap during the functioning of the two power stages. In this way it is possible to reach high values of overall efficiency, i.e., greater than 90%. The operating principle of the converter is illustrated and the dynamic behavior is analyzed. A design procedure is proposed to optimize the operating conditions. A comparison between predicted and measured results is given