MPPT Control by Using a <i>U</i>&#x2013;<i>P</i> Curve for PMSG&#x2013;Based Small Wind Turbines

Abstract

The permanent magnet synchronous generator (PMSG)–based small wind turbines (SWT) are studied in recent years because of their high reliability, high efficiency and low cost. To achieve maximum power point tracking (MPPT) without mechanical sensors and improve efficiency, a novel MPPT control method is proposed in this paper. Without measurement of the shaft speed, the conventional MPPT control strategy based on the ω–P curve does not work. However, it is possible to impose the relationship between the RMS of generator output voltage (U) and the output power (P) on the optimum operating points. The innovations focus on obtaining the U–P curve by relating the RMS of U to the shaft speed ω and designing the controller by using the control strategy based on the U–P curve. After building the whole model of the PMSG–based SWT, the RMS of U is calculated theoretically from the ω, and the U−P curve is obtained. The generator speed controller is designed by using the control strategy based on the U−P curve. The efficiency of the proposed MPPT control method is verified.