Intelligent high efficiency controller for 2-kW interleaved series resonant converters

The conventional series resonant converter (SRC) is not suitable for low input voltage and high output voltage DC/DC conversion applications. An interleaved SRC with a secondary-side resonant tank is presented in this paper to solve the resonant component design problem caused by small characteristic impedance (Zo). To support interleaving operation, two SRCs are connected in parallel with a 90 phase shift between the gating signals. Not only the input current ripple is reduced successfully, but also the device ratings can be decreased for cost saving. Without the direct support of commercial ICs, a full-custom interleaved SRC controller is designed instead. A 2-kW laboratory prototype with a 12-V input and a 200-V output is realized and tested to verify the feasibility of the proposed converter. The controller was fabricated in a TSMC 0.35μm 2P4M 3.3/5V CMOS process with a core area of 0.135 mm2 only. The duty cycle error among 4 driving signals is measured to be less than 1% and the power consumption of the controller is merely 4.8mW. The power conversion efficiency of the proposed interleaved SRC is as high as 93% from light to full load (20%~100%).