Soft switching characteristics of three level current mode push–pull bidirectional DC/DC converters
摘要
An effective way to reduce the volume and weight of a converter and improve its efficiency, is to realize soft switching to reduce the switching loss. First, the working principle of a three-level current mode push–pull bidirectional DC/DC converter is analyzed, and key waveforms of its forward and reverse working mode are obtained. Second, the soft switching characteristics of the converter are studied, and the effects of the parallel capacitance of the switch device and the excitation inductor of the transformer on the soft switching characteristics are analyzed. A transient equivalent circuit of each switch device is established at the turn-on moment. On this basis, a quasi-harmonic equation is derived during the turn-on time, and a conditional expression to realize soft switching is obtained for the switch devices. Finally, an experimental platform is built to verify the operation characteristics of the three-level current mode push–pull bidirectional DC/DC converter. The realization process of soft switching is consistent with the theoretical analysis results, which provides a theoretical basis for the selection and design of the parameters for this type of converter.