光伏储能系统恒流充电模式下光伏电池的稳定工作区

Stable Operating Area of PV Cells in Solar Energy Storage System in Constant Current Charging Mode

基于接口变换器输出恒流控制稳定的必要条件,研究揭示了光伏储能系统恒流充电模式下光伏电池的稳定工作区。以前置电容式Buck变换器为例,建立了基于光伏电池动态电路模型的连续导电模式(continuous conduction mode,CCM)系统小信号模型;分析了恒流充电模式下光伏接口变换器采用不同控制回路构成时系统的闭环传递函数,并根据赫尔维茨判据得出输出恒流控制稳定的必要条件;在此基础上,得出了恒流充电模式下光伏电池的稳定工作区;最后通过150 W样机进行了实验验证。研究结果表明:恒流充电模式下,光伏电池的稳定工作区是唯一、确定的,且稳定工作区的具体类型取决于接口变换器的控制回路构成。

From perspective stability, this paper investigates photovoltaic （PV） cells in solar constant current charging （CCC） of output current control stable operating area of energy storage system in mode. In this study, Buck interface converter with an additional input capacitor is taken as an example, and its small-signal model including dynamic equivalent circuit of PV cells is deduced. Then, close-loop transfer function of interface converter in CCC mode for different control loop formation and essential condition for output current control stability is analyzed. After that, stable operating area of PV cells feeding interface converter in CCC mode is obtained. Validity of theoretical analysis is verified with experiment and simulation of a 150 W prototype. The investigation shows that when interface converter works in CCC mode, PV cells can only operate stably in voltage area or current area. Type of stable operating area entirely depends on converter＇s output current control loop formation.