Study On Multi-Port Converter Topology And Power Management

Renewable energy can effectively solve the problems of the energy crisis and the ecological environmental pollution. However, most of the new energy is vulnerable to external conditions, leading to some disadvantages such as low energy density, power supply instability, intermittence, etc. Multi-port converter (MPC) as a new type of power electronic converter can combine new energy and energy storage elements to form multi-energy hybrid power supply system, a stable continuous and high efficient power supply can be achieved. At the same time, the converter power density and transient response speed are improved. This paper mainly studies the buck MPC topology and its power management system, and the boost MPC topology and its power management system.In the first part, a buck MPC based energy storage system is proposed, in which solar power is the primary source while the grid or the diesel generator is selected as the secondary source. Two-phase buck converter in parallel is selected as buck MPC topology. For the purpose of constant battery charging current, converter small-signal modeling is discussed in details, and dual-input single-output constant current chargeing control system are designed which facilitates the battery state of charge detection. A time-domain model with the parasitic parameters of the two-phase buck converter is established through the MATLAB/SIMULINK, which proves the effect of constant current charging control system during solar power output fluctuation. The prototype experiment indicates that the converter system can provide a constant charging current during solar converter maximum power tracking operation, especially during large solar power output variation.With solar power and battery as the input source, a boost MPC topology based power generation system is proposed, which can be connected to low-voltage PV, battery and load(independent load or grid), achieving energy exchange amomg photovoltaic, battery and grid. At the same time, the topology derivation process is introduced in details. According to the possible operation conditions of system, three working modes is proposed and its working principle is introduced in details. Combined with the circuit work waveform to analysis, calculate and model. Based on this, the PWM+ phase shift modulation (PWM+PSM) control scheme is determined, the tunning status of three working modes and mode switching is verified through PSIM simulation. The prototype experiment indicates that the converter system can achieve power generation with dual energy input, which proves the feasibility of the PWM+ PSM control scheme.