Research On CCM Soft Switch Of Flyback Photovoltaic Micro Inverter

Photovoltaic (PV) power generation as an important part of new energy power generation, developing very fast in recent years. Distributed photovoltaic power generation, with the application of the flexible and efficient characteristics, become a kind of new development prospect way of energy utilization. The inverter as the core part of electrical energy conversion in grid generation, is the key of the photovoltaic research, the flyback inverter as one of the most effective inverter. At present, the research of the flyback inverter mainly focus on improve the efficiency of inverter and system safe and stability operation. One of the key technology is inverter topology optimization design, for another, the influence of different working mode on the flyback circuit run efficiently, soft switch technology and the optimization of control algorithm and so on.The main purpose of this paper is achieve the micro inverter efficient and stable work. Firstly, summarizes the existing different topology structure design of the micro inverter, analyses the working principle and the advantages or disadvantages by comparing all kinds of designs, And then, a two-stage micro inverter is designed, first stage adopts BOOST circuit, and put battery energy storage device in DC side, second stage using isolation high frequency flyback circuit structure, and through the full bridge circuit and LC filter, eventually, the grid inverter system output high quality and same frequency current. The flyback inverter work mode choice continuous current mode, at the same time, using two lines of the flyback transformer staggered parallel connection circuit topology, doubled output power under the same voltage grade, improve system efficiency. In view of the high frequency flyback transformer leakage inductance of the energy loss and the problem of the switch tube voltage spike caused by the leakage inductance, active clamp circuit is introduced, clamping circuit used to absorb the leakage inductance energy, to eliminate the peak voltage caused by the leakage inductance and the main switch Parasitic capacitance, reduce the switch tube of overvoltage risk, achieve soft switch and reduce the circuit loss. In the aspect of System control strategy research, first stage circuit control the maximum power output of the photovoltaic panels, second stage to realize the grid current loop control, guarantee the stability of the grid system.Based on the design of the flyback inverter, this paper further studies the power load control strategies and applications of distributed PV grid system with energy storage device. In view of the problem of distribution network load demand change electricity peak valley, the control strategy was proposed based on peak of the power grid voltage compensation. In order to guarantee PV grid system running efficiency, the piecewise operation mode is proposed. The whole system parameters is designed and simulated, the feasibility of the control strategy about Grid-connected PV system with energy storage devices for peak shaving is verified, peak shaving problem is efficiently solved and the stability of the grid is maintained. This paper provides technical reference for the design of peak shaving control with energy storage system.Finally, on the basis of theory analysis and topology design, through the simulation and the micro inverter hardware platform verified the rationality of the circuit topology Structures, the software design method based on the model design, through the way of combination of MATLAB and CCS, finally proved the feasibility of the system operation, high efficiency, the proposed of the design is requirement.