Research On Flyback Micro Photovoltaic Inverter

With the depletion of traditional energy and aggravate of environment pollution, renewable energy get more and more attention. Solar energy is the most widely distributed of renewable energy, photovoltaic power generation is a common way of using solar energy, grid-connected photovoltaic power generation is the most common way of photovoltaic power generation. For the shortcomings of original grid-connected photovoltaic power generation, such as power loss and hot pots caused by partial shade covering, a new type of grid-connected photovoltaic power generation called Micro PV inverter which integrating the single photovoltaic panel and the single power electronic devices had emerged in recent years.Micro PV inverter use the modular design, each module has its own MPPT, so it can maximize tracking the maximum power, reducing power consumption and eliminating the effects of partial shading. Micro PV inverter module can Plug and Play, so it can be widely used in various small and medium power Photovoltaic power generation fields. Micro PV inverter has the characteristics of low input voltage, high output voltage and low power level, and therefore it proposed the design requirements of high power density, high efficiency, high reliability and low cost. The paper research a flyback-type Micro PV inverter using interleaved topology and active-clamp circuit, the work of the paper reads as follows.First, in the basic of studying the commonly used topology of Micro PV inverter, choose the flyback-type topology, and study the different operating modes of flyback-type converter; In order to reduce the output current’s THD and increase the converter’s power level, the front stage uses a dual interleaving paralleled topology and analyze its work process; In order to absorb leakage inductance energy of high-frequency transformer and achieve ZVS of main switch, choose an active clamp topology and research the principle and operation mode of the clamp circuit. Then, study the Micro PV inverter MPPT control strategy, and select the perturbation and observation method as the way of MPPT; use the system control strategy of MPPT loop, voltage loop, current loop and current equalizing loop; analyze the strategy of grid-connected current control, and design the proper parameters of the PI regulator. Again, according to the operating characteristics and design requirements of the Micro PV inverter, design the high-frequency transformer, decoupling capacitors, filter circuit and active clamp circuit, and choose the switching devices based voltage and current stress; according to the design parameters, the main circuit and control circuit model of interleaving paralleled active clamp flyback-type Micro PV inverter are built in PSIM, and be verified reasonable by simulation. Finally, use DXP to design the hardware of Micro PV inverter’s main circuit board and sensor board, and draw the schematic and PCB board; choose DSP28335as the control chip, and accomplish the design of system main program and ADC, CAP and other routine program; build a115W Micro PV inverter experimental platform and conduct the grid-connected current test experiments.Through the research, design, simulation and experiment of Micro PV inverter, the paper gives the system design methods of Micro PV inverter, verifies the effectiveness of interleaving paralleled topology and active clamp circuit, and be able to be reference for the further research of Micro PV inverter.