离网无蓄电池光伏制冷系统的反馈控制研究

Research on Feedback Control of Off-grid Photovoltaic Cooling System without Storage Battery

为达到光伏发电系统在离网无蓄电池条件下直接驱动变频压缩机制冷的目的,提出了光伏组件输出400~800V直流电压下变频压缩机能够稳定运行的反馈控制策略,构建了以电机转速为反馈信号的最大功率点跟踪(MPPT)控制模型.理论分析表明逆控机转换效率约为80%,实际工况实验结果表明逆控机转换效率在70~90%之间,验证了控制模型的正确性.对MPPT反馈控制算法进行了不同工况实验,通过电机转速自动调整MPPT的基准电压点,可为离网无蓄电池光伏制冷系统提供稳定的三相交流电能.实验结果表明,采用更低启动频率反馈控制后光伏系统发电效率可提高至9%,且系统的cop为0.15,cop增加了15.4%.

In order to achieve the purpose of directly driving the inverter compressor using photovoltaic power generation system under the condition of off grid and without storage battery,a feedback control strategy for the stable operation of the inverter compressor suitable for PV array output under 400-800V DC voltage was proposed,and the maximum power point tracking（MPPT）control model based on the motor speed is presented.The theoretical analysis shows that the conversion efficiency is about 80%,and the experimental results show that the conversion efficiency of the inverse controller is between 70-90%,which verifies the correctness of the control model.The MPPT feedback control algorithm has been tested under different conditions,and the reference voltage of the MPPT can be adjusted automatically by the motor speed,which can provide a stable three-phase AC power for the off-grid photovoltaic cooling system without storage battery.The experimental results show that the photovoltaic power generation efficiency can be increased to 9%,and the copof system is increased to 0.15,which is increased by 15.4%,which proves the effectiveness and feasibility of the direct drive MPPT control strategy.