Transformerless DC-DC PWM converters

Three new transformerless step-up DC-DC PWM converters are proposed. They put the switching structure into the step-up DC-DC converters to achieve higher voltage gain when the duty ratio is not extremely high, and the switching structure is composed of three inductors and six diodes (switched-inductors). The switched-inductors in the basic DC-DC converters can realize the step-up of the voltage, which is achieved through charging and discharging. The output voltage gain can be determined by the steady-state analysis of the new proposed converters. This paper deduces the gain of the line voltage, and the gain formula shows that the proposed converters can realize higher gain than the basic converters. The proposed new converters have many advantages, mainly reflected in these aspects: less economic burden, smaller size, smaller conduction losses. The simulation results confirm the theoretical analysis.