A New Transformerless Four Quadrant DC-DC Converter with Wide Conversion Ratio

In this paper, a new transformerless four quadrant DC-DC converter, which can be used in some applications such as DC motor driver system, is proposed. Compared with existing four quadrant DC-DC converters, the proposed four quadrant converter can not only provide bipolar voltage and bidirectional current for load, but also have buck-boost characteristics for both positive and negative output voltage. Theoretically, as the duty cycle increases from zero to one, the output voltage ranges from positive infinity to negative infinity and is equal to zero when duty cycle is zero point five. In addition, analyses about the circuit principle and steady-state calculations are presented. Finally, the experiments are carried out to verify the effectiveness of this new transformerless four quadrant DC-DC converter.