Grid-connected Micro-inverter Research And Design

With the depletion of fossil fuels, all countries are racing to seize the new energy. Solar energy comes out at the top of the new energy as solar energy is inexhaustible. Many scholars are doing some research on the use of solar energy, so the solar photovoltaic power generation system is proposed and the inverter, which is the core component of the photovoltaic power generation system, plays an important role in the whole system. In this paper, I make a scruting from the output DC voltage of solar panel to the grid-connected photovoltaic system, further design a micro-inverter for 200 watts of power.This paper proposed a micro-inverter with push-pull full-bridge inverter circuit based on the exhaustive study of the existing inverter circuit structure. According to the working principle of the solar panels, analyzing the effect of light and temperature on the output power, I proposed the variable step conductance incremental algorithm, and this algorithm can keep the maximum power point tracking even if the output power changed, improve the tracing accuracy, and avoid oscillation at the maximum power point. Other than that, Studied the effect of SPWM generation method, control algorithm and triangular carrier modulation method on the circuit output voltage, Put forward the LC-LC series filter circuit, When the circuit of the load changes, total harmonic distortion of the output voltage is effectively reduced, reached 0.96%, and the output waveform is more stable. This paper designs a micro inverter, the test results show that when the input DC rated voltage is 24 V, output AC voltage effective value is 220 V, frequency 50 HZ, power reaches 200 W, the transformation efficiency reached 85%, achieve the design index.In-depth study of several control strategy algorithm of the grid connected photovoltaic system. Study the current hysteresis comparison control, PID control and deadbeat control algorithm for the simulation, analysis the advantages and disadvantages of these three algorithms, laid the theoretical foundation for the photovoltaic grid connected power system.