光伏并网逆变器损耗分析及效率优化控制

摘要

Taking two-stage grid-connected photovoltaic inverter with former stage being Boost and backward stage being full bridge inverter for example,its power losses calculation method was studied.The formula for losses calcu-lation was derived.It shows that the losses of two-stage grid-connected photovoltaic inverter have close relationship with its middle bus voltage.Different middle bus voltage impacts the losses of switch devices,diodes and inductors, and the inverter efficiency ultimately. Based on the losses formula,the specific loss values of each device are cal-culated in detail. Then a method of three loop control strategy with MPPT(maximum power point tracking)in for-mer stage and MEPT(maximum efficiency point tracking)in backward stage was proposed to search the maximum power point and efficiency point. The experiment results verified the feasibility and validity of proposed loss analysis model and MEPT control strategy.%以前级Boost、后级全桥逆变器的两级式光伏并网逆变器为例,研究其损耗的计算方法,推导出用于损耗分析计算的公式.分析表明两级式光伏并网逆变器的损耗与其中间母线电压关系密切,中间母线电压的选择直接影响开关管、二极管、电感的损耗,最终影响变换器效率.利用损耗公式,对各器件的具体损耗数值进行详细计算.提出前级采用最大功率点跟踪算法搜寻阵列最大功率点,后级采用最大效率点跟踪算法在线搜寻最大效率点的三环控制策略.搭建实验样机,实验结果表明损耗分析模型和最大效率点跟踪策略的正确性和可行性.