Analysis Of Parasitic Parameters Of Common Structure In Medium&High Power Photovoltaic Systems

The high frequency on-off of switch devices in photovoltaic(PV)system leads to high du/dt and du/dt.The parasitic capacitance and inductance in the circuit will produce larger current and voltage on higher du/dt and di/dt,which will not only have a negative impact on the system itself.It could even endanger the safety of people.In order to solve the problem of high du/dt and di/dt in switching devices,the researchers of power electronics have studied the PV system from the perspective of topology and control strategy and got some optimized topology and control strategies.Because of the high cost and the complexity of control,many researches can not be applied to the actual engineering field.In fact,a series of problems caused by high frequency are directly related to the parasitic parameters in the system.One is to provide a conduction path for interference(parasitic capacitance),the other is to act as an inductor(parasitic inductance).In general,the larger the parasitic parameter,the more serious the interference.If the parasitic parameter in the system is reduced,the impact of du/dt and di/dt on the system will also be reduced.Based on the above ideas,aiming at the problems of leakage current and overvoltage in large power PV system,the parasitic parameters related to the common structure are studied in this paper.The object of study is the PV module and busbar.In this paper,the parasitic capacitance and inductance are modeled and analyzed systematically by the finite element simulation software,and the influence factors of the capacitance and inductance are studied to give a clear claims,at the same time,some misleading conclusions are corrected.The electromagnetic mechanism behind the two parasitic parameters is also explored.Several optimized design ideas are proposed to reduce the parasitic capacitance of PV module and the parasitic inductance of the busbar.It provides a new idea for the problem of leakage current and peak voltage in PV system.