Wide range soft switching PWM three-level DC-DC converters suitable for industrial applications

This paper discusses wide range soft switching solutions to a pulse width modulation (PWM) three-level (TL) dc-dc converter suitable for industrial applications, and proposes four kinds of new PWM TL dc-dc converters. The presented topologies have the following desirable features: all switches in each circuit sustain only half of the input voltage; off state voltage of the switches is directly clamped by the input capacitors and no added primary clamping devices, such as clamping diodes, flying capacitors, are required; and phase shifted control method can be used to achieve wide output range. The leading switches in the converters can only realize zero-voltage switching (ZVS), while the lagging switches can obtain ZVS or zero-current switching in different converters. Principle of operation and theoretical analysis are discussed. Experimental results are included to verify the feasibility and advantages of the new topologies.