Wide Load Range ZVS Three-Level DC-DC Converter: Four Primary Switches, Capacitor Clamped, Two Secondary Switches, and Smaller Output Filter Volume

A novel soft-switching PWM three-level (TL) dc-dc converter with two added secondary switches is proposed. The proposed converter has following good features: four primary switches sustain half of the input voltage; the primary circuit is simpler and more compact due to only one flying capacitor with smaller current stress is required to clamp off state voltage of the primary switches; the secondary rectified voltage before the output filter is a TL waveform, which significantly reduces the requirement of the output and input filters; all primary switches can obtain ZVS in wide load range. Furthermore, less conduction loss is added. The added secondary switches can obtain zero-current switching independent of the load current. The proposed converter can be extended to higher voltage level easily due to simpler and more compact primary structure. In addition, the presented converter is also well suitable for high-input dc interfaces with independent controllable multioutput ports. The operation principle, soft switching characteristics, and some important analyzes are presented in this paper. The proposed converter is verified by the experimental results from a 10-kW prototype.