Investigation on the optimal operation and control strategy of a wide‐range switched‐capacitor/switched‐inductor DC/DC converter

Wide-range DC/DC converters are widely used in telecommunications, electric vehicles, and e-bikes. In this paper, the operation characteristics of the wide-range cascaded buck converter with two duty cycles are investigated. The operation principle of switched-capacitor and switched-inductor is analyzed to ensure that there are no current or voltage spikes in the system and no additional control is required for them. Based on the volume and efficiency performance indexes, the optimal operating region of the converter should be selected to the left side of the minimum sum point of the two duty cycles. The small signal model of the converter is established, then a control strategy is proposed that the first-stage duty cycle is directly given based on the optimal operating region, and the second-stage duty cycle is determined by double closed-loop control, which has good control performance, economy, and simplicity. The prototype achieved the conversion of 32 to80 V to 5 V/6 A with peak efficiencies of 92.4%/80 V, 93.8%/48 V, 94.5%/32 V. The results proved that the control strategy enables the converter to realize high efficiency and rapid dynamic regulation even in the condition of high voltage gain and wide input range.