Design And Research Of Photovoltaic Inverter Based On DSP28335

Due to air pollution and depletion of mineral resources,attention has been paid to renewable energy in recent years.As a green alternative energy,solar energy,which has the advantages of clean and renewable,has become one of the effective ways to solve the air pollution and the depletion of mineral resources.With the progress of science and technology,related technologies of solar power generation have gradually matured.However,there are still some problems that seriously limit the promotion and application of photovoltaic power generation,such as: the cost is still high,the power generation efficiency is low,and the economy is poor.Therefore,how to improve the efficiency of solar power generation system and how to reduce capital investment has become the focus of scientific research in this field.In this paper,photovoltaic inverter is researched and designed to improve system efficiency.The photovoltaic inverter studied in this paper is discussed from the following aspects.(1)Because of the nonlinearity of conversion efficiency and power voltage characteristics of PV generation.Therefore,we need to improve the output efficiency through the maximum power point tracking technology.In practical applications,when the sun is blocked by clouds,the speed of light change will also be different due to the different speed of cloud moving.When the intensity of light intensity changes quickly,the traditional Perturbation and observation is likely to be misjudged.In the case of non uniform change of light intensity,the disturbance observation method based on power prediction can also be misjudged,causing the system to have no work near the maximum power point.To solve the above problems,we introduce the concept of illumination change rate,so as to reduce the misjudgement caused by uneven illumination intensity.At the same time,the fixed step length can not meet the dynamic and steady state performance of the system at the same time.In this paper,the optimal step length coefficient can be selected according to the conditions of light change,and the tracking efficiency of the system can be improved by using the improved variable step length coefficient.(2)In practice,some modules are often blocked by clouds,high buildings and tree shades.When photovoltaic panels encounter shadow occlusion,the power voltage curve of the photovoltaic module appears multiple local maximum points.At this time,the traditional algorithm may only track the local maximum point,and fail to track the Global maximum power point(GP).In view of the above problems in partial occlusion,the curve of photovoltaic cells under the condition of complex illumination is analyzed.At the same time,combined with the advantage that the measurement algorithm can quickly and accurately search the local peak points,the measurement algorithm is used to scan the curve of the photovoltaic array under partial occlusion and search out all local peak points,and GP is judged by the difference between the measure of GP and the measurement of other local extreme points.(3)For the inverter link of photovoltaic inverter,the principle of the traditional SVPWM algorithm is introduced.On this basis,the principle of zero sequence carrier PWM algorithm which is equivalent to the control effect of the SVPWM algorithm is analyzed.(4)To build a simulation model of photovoltaic system under the environment of PSIM,the improved power prediction MPPT algorithm and zero sequence carrier PWM algorithm are simulated and analyzed.The results show that the MPPT algorithm can accurately track the GP of the photovoltaic array,and the PV inverter can output the power frequency sinusoidal alternating current energy.(5)The main control circuit,including the driving module and the sampling module,is designed with the TMS320TM28335 of the Texas Instrument instrument manufacturer as the control chip of the system.At the same time,the program of MPPT control,inverter control and human-computer interaction is designed in the CCS3.3 compiling environment.The above modules are verified by experiments.