A current shaping control CSC scheme for the resonant four-switch inverting buck-boost dc/dc converter is proposed to overcome the drawbacks of traditionally used control schemes, such as a Pulse Density Modulation based DCM control scheme and a fixed duty ratio with modified phase shift control scheme. In the proposed CSC scheme, a four segments of resonant inductor current have been examined using duty ratio and phase shift as control variables with the whole load and voltage range of ZVS turn-on soft switching condition. Meanwhile, the rms value of the resonant inductor current is low compared with discontinues current mode (DCM), which is directly proportional to the conduction loss, and efficiency of the converter.
For the verification of the proposed control scheme, a resonant four-switch inverting buck–boost dc/dc converter is designed and experimentally tested, which has recorded over 98.4% peak efficiency at a 1:1 inverting case (-48 Vdc to 48 Vdc). The converter’s wide operating range is from -48 Vdc input to 28 to 60 Vdc output voltage with the power density of 540W/in3.
Fig. 1. The circuit diagram of a resonant four-switch inverting buck-boost dc/dc converter and its operating waveform
Fig. 2: Power board of a resonant four-switch inverting buck-boost DC/DC converter
