Built-in Parallel Time-sharing Selector Switch Full-bridge Buck Type Distributed Power Generation System

Renewable energies such as solar energy,wind energy,geothermal energy and ocean energy are widely distributed,with abundant reserves,clean and pollution-free,and their development and utilization have received increasing attention from governments around the world.However,single new energy power supply usually has many defects such as being unstable and discontinuous and changing with climate.In order to improve the stability and flexibility of the power generation system,it is necessary to use the distributed generation system with multiple new energy joint power supply.Based on the exposition of the single input DC-DC converter type and multi-input DC-DC converter type two-stage distributed generation system,this paper proposes a full-bridge Buck type distributed generation system with built-in parallel time-sharing selector switches.And the thorough theoretical analysis and simulation research of some key techniques such as circuit topology,energy management control strategy,steady state principle characteristics,and design criteria for main circuit parameters that constitute this generation system are comprehensively carried out.The circuit topology of the distributed generation system with built-in parallel time-sharing selector switches is proposed and analyzed.It consists of a full-bridge Buck type single-stage multi-input inverter with built-in parallel time-sharing selector switches and a single-stage isolated bidirectional charging /discharging converter with energy storage element,and they are connected in parallel on the AC load side.The former is cascaded by input filter,full-bridge multi-input single-output high-frequency inverter circuit with built-in parallel time-sharing selector switches,output filter inductor(including leakage inductance),output transformer,and output filter capacitor in sequence.The latter is a single-stage bidirectional full-bridge Buck mode high-frequency link rectifier /inverter with secondary ripple suppression circuit.The maximum power output energy management control strategy with the output voltage independently controlled loop of single-stage isolated bidirectional charging /discharging converter is proposed and analyzed,which includes maximum power output energy management SPWM control loop of the single-stage multi-input inverter and rectifier-like unipolar phase shift control loop of the bidirectional charging /discharging converter.Multi-input sources realize their maximum power output,and according to the relative-size of the AC load power and the total power of multi-input sources,the strategy can control the direction and size of the bidirectional charging /discharging converter’s power flow in real-time and realize the stability of the load voltage and the smooth and seamless switching between the three operational modes.This paper deeply analyzes and studies on the high-frequency switching process,external characteristic curves,duty cycle of multi-input sources of the system.And the suppression techniques of power switches voltage spike,DC bias of load voltage and secondary current ripple of energy storage element are discussed.The design criteria for the main circuit parameters such as input and output filters,turns ratio of the transformers,secondary current ripple suppression circuit,voltage and current stress of the power switches are deduced.The current and voltage regulators are designed on the basis of establishing the small signal model of the system.A 3kVA 240-360VDC/220V50 HzAC full-bridge Buck type distributed generation system with built-in parallel time-sharing selector switches is designed.The PSIM steady-state and dynamic simulation results confirm the correctness and feasibility of the proposed circuit topology and energy management control strategy,which have shown that the system has the characteristics of three operational modes,simple circuit structure,single-stage power conversion except the case of charging to energy storage element,high conversion efficiency,multi-input sources parallel time-sharing power supply,galvanic isolation among multi-input source,energy storage element,and AC load.It provides an effective new method for the distributed generation system with multiple new energy joint power supply.