Switched-mode power supplies using a new series resonant inverter topology

The advantages of both switched-mode power supplies and resonant converters are well known. The paper aims to introduce a new switched mode power supply based on an original zero-current-switching (ZCS) series resonant inverter (SRI) topology. This inverter includes an input inductor L_s, two switches, and the resonant path C-L_LL -R (the transformer primary winding (L_LL-R) is connected in series with the resonating capacitor). The main advantages of the proposed inverter are as follows: simple structure of the power and control circuits, high frequency operation, soft switching at turn-on/off of the power devices; connected with a noncontrolled rectifier as power source, the inverter forms a resonant converter practically having a unity AC power factor. The paper presents the basic principles and the theoretical analysis of the inverter behavior, some considerations on the commutation and turn-off switches losses. The Pspice simulation, a few experimental waveforms and a quality/efficiency discussion over a switched-mode power supply including the proposed inverter are also included