Back-EMF-Based Multi-Loop Sensorless Control of Solar PV-Powered Brushless DC Motor Drive for Sustainable Agriculture

The multi-loop control of a permanent magnet brushless DC motor (BLDCM) is proposed in this paper for solar photovoltaic (SPV)-based irrigation system. The BLDCM is controlled in sensorless mode with an estimation of Hall-effect signals through back-electromotive-force (EMF)-based approach. The multi-loop control system enables the control of DC input of the three-phase voltage source inverter, and the speed, torque and stator currents of BLDCM. The smooth acceleration of the rotor is proposed during starting while operating the motor with multi-loop control. The stability of multi-loop is comprehensively analyzed, and the overall system is made stable with the proposed sensorless technique throughout the operation. The degree of protection is therefore enhanced, resulting in a robust and reliable irrigation system. The maximum power point tracking (MPPT) is incorporated with SPV array to generate the maximum operating speed of the motor. The desired operating speed of BLDCM is derived by subtracting the speed-loss from the abovementioned maximum speed. The buck-boost converter is employed for the said purpose to achieve an unbounded region for MPPT. This also offers flexibility for sizing the SPV array and the motor. The response of the designed system is verified under varying operating conditions through the MATLAB-based simulation followed by real-time experimentation.