Research On Interleaved Isolated Bidirectional DC-DC Converter With Coupled Inductor

Currently,clean new energy is widely used in various fields because of its non-polluting and reproducible properties.However,these new energy sources are inferior to external interference,so they are usually connected with energy storage equipment to form a reliable and stable power supply.The device forms the microgrid.The bidirectional DC-DC converter is one of the most important converters,enabling energy to be transmitted bidirectionally between the bus and the energy storage device.The bidirectional DC-DC converter based on bridge structure has the advantages of high transmission power and front-to-back isolation.This paper compares and analyzes the control strategy of two-way isolated full-bridge converter.It also introduces a pre-stage inverter based on interleaved parallel.The isolated bidirectional DC-DC converter with structure and rear-stage bridge rectifier structure is studied in detail.Firstly,the working mode principle,transmission power characteristics,reflow power characteristics and current stress of the isolated full-bridge bidirectional DC-DC converter under the extended phase shift and double phase shift control strategies of single phase shifting and internal phase shifting parameters are analyzed.Features and conditions for zero voltage switching of the switch tube.On this basis,the converter performance under three control modes is compared,including the converter power transmission range,the converter return power characteristics and current stress under the same transmission power condition.Secondly,based on the isolated full-bridge bidirectional DC-DC converter,the pre-stage full-bridge structure is transformed into a coupled-inductor interleaved parallel structure,and a new isolated bidirectional DC-DC converter based on interleaved parallel structure is obtained.The stable operating mode principle,power characteristics and soft switching characteristics of the converter under single-shift control parameters are described in detail.After increasing the duty cycle parameter,the modal principle and power characteristics are analyzed under a new control strategy.The transmission power range,the maximum value of the inductor current and the return current of the converter under the two control modes are compared and analyzed.Then,the optimal control of the isolated bidirectional DC-DC converter with staggered parallel structure is analyzed.Under the premise of single phase shift parameter control,the internal shift comparison parameters of the interleaved parallel structure are increased,so that the output voltage of the low-voltage-side inverter structure accounts for the duty ratio is adjustable to form phase shift control with single PWM.The converter power characteristics,inductor current stress and soft switch implementation range under this control are analyzed in detail,and compared with the converter characteristics under single phase shift control.And optimize the phase shift control with single PWM based on the optimal maximum inductor current.Finally,the hardware system design of the interleaved parallel isolated bidirectional DC-DC converter is completed.The forward boost mode of the converter under single phase shift control and single PWM plus phase shift control was tested.At the same time,the boost mode experiment under optimized single PWM plus phase shift control was completed.