The encoder influences reliability and cost of permanent magnet synchronous motor (PMSM) operated solar water pump (WP). It is even sensitive to electromagnetic noise and temperature, which thereby reduces its accuracy. To overcome these problems, an encoderless PMSM control by using adaptive hybrid generalized integrator (AHGI) based sliding mode observer (SMO) for the solar WP system is presented in this paper. The widely used low pass filter based SMO produces phase-shift, attenuation and dominant lower order harmonics (DLOH). This decreases the position estimation accuracy. Besides, the need for tracking dynamic system frequency further exacerbates its performance. The developed AHGI structure eliminates these drawbacks and provides an accurate estimate of position over a wide speed range. A harmonic decoupling network, a hybrid generalized integrator and an adaptive frequency tracker constitute AHGI, which respectively performs dominant harmonic signal generation, DLOH elimination and frequency tracking. The improvement in behavior of AHGI over the existing methods is analyzed by transfer functions, Bode plots and back electromotive force helices. Meanwhile an incremental conductance algorithm for PV array maximum power control is used. The developed structure is experimentally validated on a laboratory prototype and a comparison with the existing methods is also made.
- Solar water pump
- Solar photovoltaic (PV) array
- Encoderless control
- Adaptive hybrid generalized integrator (AHGI)
- Adaptive frequency tracker (AFT)
Fig. 1 Encoderless PMSM driven solar WP system with developed AHGI based
SMO for rotor position estimation
EXPECTED SIMULATION RESULTS:
Fig. 2 Experimental performance of the solar WP system with the developed AHGI based SMO (a) Starting at 1000 W/m2, (b) Starting at 500 W/m2, (c),(d) continuous running at 1000 W/m2, (e),(f) continuous running at 500 W/m2
Fig. 3 Experimental dynamic performance of solar WP system with the developed AHGI based SMO for irradiation variation from (a),(b),(c) 500 W/m2 to 1000 W/m2; (d),(e),(f) 1000 W/m2 to 500 W/m2
An adaptive hybrid generalized integrator (AHGI) based SMO for encoderless operation of PMSM driving a solar WP has been presented here. It has been found that the developed AHGI structure has produced a satisfactory estimate of both the speed and rotor position through selective elimination of DLOH along with the removal of phase-shift and fundamental attenuation. The improved performance of AHGI structure over the LPF, SOGI and FOGI has been demonstrated by the transfer function and the frequency response. Besides, the superiority of AHGI has also been shown through both the simulated and experimental performances of back EMF and rotor position. Even the detailed experimental performance of system with the AHGI at continuous running and starting under dynamics of solar irradiation have been obtained. It has been found that the developed AHGI structure has produced a satisfactory estimate of αβ-components of back-EMF even under dynamics. It has also been shown experimentally that the developed AHGI successfully tracks the variations in the speed. A stable and reasonably satisfying performance of the system has been observed under all operating conditions. The developed AHGI structure can be used with any PMSM system for rotor position and speed estimation.
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