In order to optimize the solar photovoltaic (PV) generated power using a maximum power point tracking (MPPT) technique, a DC-DC conversion stage is usually required in solar PV fed water pumping which is driven by a brushless DC (BLDC) motor. This power conversion stage leads to an increased cost, size, complexity and reduced efficiency. As a unique solution, this work addresses a single stage solar PV energy conversion system feeding a BLDC motor-pump, which eliminates the DC-DC conversion stage. A simple control technique capable of operating the solar PV array at its peak power using a common voltage source inverter (VSI), is proposed for BLDC motor control. The proposed control eliminates the BLDC motor phase current sensors. No supplementary control is associated for the speed control of motor-pump and its soft start. The speed is controlled through the optimum power of solar PV array. The suitability of proposed system is manifested through its performance evaluation using MATLAB/Simulink based simulated results and experimental validation on a developed prototype, under the practical operating conditions.
- Solar PV array
- BLDC motor
- Water pump
- Soft starting
- Speed control
Fig.1 Proposed water pumping based on a single stage solar PV energy conversion system.
EXPECTED SIMULATION RESULTS:
Fig.2 Steady state and starting performance of (a) PV array and (b) motor pump, of proposed system at 1 kW/m2.
Fig.3 Steady state and starting response of (a) PV array and (b) motor-pump, of proposed system at 200 W/m2.
Fig.4 Dynamic performance of (a) PV array and (b) BLDC motor Pump ,of Proposed water pumping system.
Fig. 5 Responses of (a) PV array and (b) BLDC motor, under partial shading
The proposed BLDC motor driven water pumping based on a single stage solar PV generation has been validated through a demonstration of its various steady state, starting and dynamic performances. The system has been simulated using the MATLAB toolboxes, and implemented on an experimental prototype. The topology of the proposed system has provided a DC-DC converter-less solution for PV fed brushless DC motor driven water pumping. Moreover, the motor phase current sensing elements have been eliminated, resulting in a simple and cost- effective drive. The other desired functions are the speed control without any additional circuit and a soft start of the motor-pump. A detailed comparative analysis of the proposed and the existing topologies has ultimately manifested the superiority of the proposed work.
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