Hybrid Energy Storage Module in Photovoltaic Power Generation System for Brushless DC Motor Operation

Photovoltaic power generation systems often suffer from voltage instability and intermittent production of electricity due to shade, dust, rain, and so forth, resulting in unstable power quality. Such problems of photovoltaic power generation systems cause the malfunction of devices connected to the system, especially in systems with brushless DC motors. To solve these problems, a hybrid energy storage module and a precise control strategy for photovoltaic power generation systems are proposed. The system comprises solar cells, a hybrid energy storage module, a power conversion module, a sensing-type pyrheliometer, and a brushless DC motor. The hybrid energy storage module is composed of a supercapacitor and a lithium-ion battery, which are connected in parallel. The power conversion module includes a maximum power point tracking converter, a boost converter, a controller, and switches. The sensing-type pyrheliometer monitors the luminous intensity during operation, which enables the controller to analyze the signals of the system and control the system through the terminal voltage of the hybrid energy storage module. A brushless DC motor is connected to the system to investigate by how much the power quality and operation time are improved. The experimental results show that the system has a sustainable power supply because the brushless DC motor operates for up to 342 s without any interruption, longer than that for a photovoltaic system with a supercapacitor only. Thus, the photovoltaic power generation system with the proposed hybrid energy storage module and the control strategy effectively reduces the voltage instability and the interruption of power generation and improves the quality of the power.