The Research And Design On The Non-Isolated Single Phase Grid Inverter

With the exhaustion of traditional fossil energy ,people have to look for more and more alternative energy. People attached an increasing importance on PV generation as an clean energy. It is necessary to design an efficient grid inverter because of current low efficient. The improvement of inverter efficient involves MPPT, grid algorithm and filter design. In this paper ,these technology have been researched.In the introduction of paper,the topology and structure has been summarized. In the next chapter, some key points like the technology of max power point tracking, grid-connecting control strategy and island protection are discussed. Moreover, the Matlab simulation is essential to verify the feasibility of the scheme. In order to reduce the harmonic current into the grid network, a kind of LCL fliter with resistance has been designed to alleviate harmful effect on waveform quality caused by the resonance. At the end of the paper, the hardware circuit of single phase inverter based on the TI C2000 DSP has been provided including the main circuit, control circuit and peripheral circuit.One difficulty of distributer generation is isolation detection whether active and inactive. The principle of inactive method is to detect gird parameters to verdict the isolation and the active detection is to inject some disturbance in the grid to break the load balance, so the isolation can be detected. Of course, the current disturbance based on DSP proved the accuracy of the method and no NDZ in the single machine.At last, the grid connecting experiment in laboratory achieves the current tracking of grid voltage. The FFT analysis of the current verifies the LCL filter with resistance can reduce the harmonic in the current. So the design scheme has certain rationality and potential practical perspective.