Design Of Micro-grid Photovoltaic Inverter Based On STM32

The State Energy Administration emphasized the importance of strengthening the development and utilization of distributed new energy,optimizing the layout of solar energy development and giving priority to the development of solar photovoltaic power generation.However,large numbers of distributed photovoltaic access will cause a certain burden.At this moment,the microgrid based on distributed generation has played an important role,and the photovoltaic inverter is facing the challenge in the microgrid market.In this paper,the hardware circuit and software control circuit of photovoltaic inverter based on STM32 microgrid has been researched and designed.The main circuit design of microgrid PV inverter has been composed of the first stage Boost DC/DC and full bridge inverter circuit.The key technologies were composed of the maximum power point tracking technology,low frequency ripple suppression technology,and grid control technology.Among them,a photovoltaic cell using double diode structure,using improved particle swarm optimization algorithm to complete the maximum power tracking technology,realizing the maximum power multi pole fast intelligent tracking function;inverter ripple suppression control strategy of the voltage and current double closed-loop,In the middle busbar,the bandwidth of the voltage loop of the converter is regulated by adjusting the magnitude of the disturbance,improving the speed of calculation and the regulation ability of the negative feedback in the load fluctuation process,and then suppressing the fluctuation of the two ripple voltage of the bus voltage.The perturbation size is determined by the load,when the load fluctuation,by sampling the output current and then sent to the controller of STM32,according to the control current and voltage double loop can regulate external disturbance adaptive disturbance,can effectively restrain the low frequency ripple interference.The disturbance of the size determined by the load,when the load fluctuation,by sampling the output current and then sent to the controller of STM32,according to the control current and voltage double loop can regulate external disturbance adaptive disturbance,can effectively restrain the low frequency ripple interference.Synchronous control technology is the key technology of photovoltaic grid-connected.The output voltage of solar panels is successfully converted to sinusoidal acvoltage used the improved PI control technology.This sinusoidal ac voltage has the characteristics of low harmonic distortion,and phase and frequency of the sinusoidal ac voltage are the same as them of grid voltage,sinusoidal ac power also can be inputted the power grid.Two stage photovoltaic inverter system adopts the control method.In the process of ripple suppression analysis,PSIM9.1.1 is used to model and simulate it.In the process of using MATLAB to build a simulation model,using S-function to design the particle swarm algorithm which is needed in maximum power tracking technology,this algorithm successfully realizes the multi pole maximum power tracking technique under the shadow,and the algorithm supplies the shortcomings of the local concussion in traditional algorithm and improves the efficiency of work.The simulation model of synchronous control method based on PI control is established by using the MATLAB/Simulink platform.The parameters of public power grid are set to the frequency of50 Hz and the AC power of 220 V,and the output power capacity of the inverter is about 1kW.Similarly,Powergui tools are used to analyze the output current signals,and harmonic analysis is applied to meet the requirements of national grid standard successfully.The hardware parameters of the boost topology and the full bridge inverter topology are calculated in detail,and the detailed selection of the components is made to determine the specific model.In the control circuit,the STM32 chip is used to adjust the output of driving signa and negative feedback voltage.To achieve the purpose of boost in the first stage,the full bridge inverter topology changes the DC voltage of the front stage to the AC power of 220 V through the SPWM wave driven by the STM32 main chip.The construction of the experimental platform,the debugging of hardware and software and the test of oscilloscope fully verify accuracy of the research scheme.