Two-phase induction motor drive improvement for PV water pumping system

In recent years, solar energy sources have been widely utilized, especially in PV water pumping system. Single-phase induction motors (SPIM) are the most common type of motor used in PV pumping application. Reliable operation, low cost and low maintenance are the main advantages of SPIM. However, SPIM have an inherent problem of low efficiency at low speeds, which can be overcome by the adoption of two-phase induction motors (TPIM). This paper proposes a new speed control method for the TPIM used in PV water pumping system. The TPIM is supplied with unbalanced two-phase voltages generated by the inverter that employs the carrier-based SVPWM switching strategy. The V/F control is incorporated to realize variable speed operation. The motor reference speed is set to be proportional to the power generated by the PV array. As a result, the motor speed always tracks power fluctuation of the PV array, leading to improved system efficiency. The validity of the proposed method is verified by simulation results.