Single Stage Solar PV-Battery Based Hybrid Water Pumping System Using BLDC Motor Drive

Water pumping is one of the significant applications of solar energy. The solar pumping system can be categorized into two types based on the number of power conversion stages: single-stage and multi-stage. In multi-stage systems, a DC-DC converter is required to ensure the maximum power point tracking (MPPT). However, this power conversion block leads to increased costs, size, complexity, and reduced system efficiency. In this study, a single-stage solar pumping system using a brushless DC (BLDC) motor is designed to eliminate the need for a DC-DC converter. The single-stage structure is preferred over the multi-stage structure due to its advantages, and the BLDC motor is chosen for its suitability in solar pumping systems. In the proposed system, a hybrid photovoltaic (PV) and battery source is utilized to ensure consistent pumping volume regardless of weather conditions. The PV array serves as the primary power source, while the battery acts as a backup. The battery is discharged only during unfavorable weather conditions or at night when the PV array cannot provide power to the motor-pump. Conversely, when water pumping is not required or the PV power exceeds the motor-pump's power demand, the extra power is stored in the battery, which is then charged. A bidirectional charging control system is employed to automatically switch the battery's mode of operation using a bidirectional converter. To control the BLDC motor, a simple control technique is proposed, which allows the solar PV array to operate at its peak power using a voltage source inverter (VSI).