Sliding Mode Observer Based Voltage-Sensorless Model Predictive Power Control of PWM Rectifier Under Unbalanced Grid Condition


A sliding mode grid voltage observer (SMGVO) is proposed and tentatively checked in this paper for voltage-sensorless task under an uneven system. Fundamental positive sequence component (FPSC) and Fundamental negative sequence component (FNSC) are naturally isolated in the spectator without utilizing any extra channels. Because of implanted sifting impact, high recurrence prattling and symphonious swells can be all around stifled. Furthermore, DC segment can be totally dismissed. Subsequently, DC balance would not cause principal recurrence motions in greatness and recurrence of the evaluated FPSC and FNSC. Inferable from the prescient capacity of SMGVO, one-advance postponement can be specifically repaid utilizing state factors in the eyewitness. By joining estimation and forecast into one phase, the structured SMGVO ends up being a minimized answer for limited control set-demonstrate prescient power control (FCS-MPPC) without voltage sensors. Hypothetical evidence is inferred to check that FPSC and FNSC can be precisely evaluated and isolated. Test results acquired from a two-level PWM rectifier affirm the viability of the entire control framework.





Fig. 1. Control diagram of SMGVO based FCS-MPPC.



 Fig. 2. Startup responses with 50% voltage dip in phase A. (a) Actual grid voltages, currents and estimated voltages; (b) comparison between estimated voltages from SMGVO and calculated voltages from DSOGI.

Fig. 3. Operation from balanced condition to unbalanced condition. (a) Actual grid voltages, currents and estimated voltages; (b) comparison with usogi p and usogi n calculated from actual voltage by DSOGI.


Fig. 4. Dynamic responses when Pref steps from 600 W to 1000 W.

Fig. 5. Steady state responses with 1.5 V DC component and 50% AC voltage dip in phase A.

Fig. 6. Average switching frequency fsw when Pref = 1 kW.

Fig. 7. Spectrum analysis of (a) grid voltage, (b) ^up and (b) ^un under unbalanced and distorted grid conditions.

Fig. 8. Estimated grid frequency with sudden frequency step change of +10 Hz under unbalanced and distorted grid conditions.


A SMGVO is structured and tentatively checked in this paper. It has the accompanying properties: 1) inborn detachment of FPSC and FNSC without using any channels; 2) no high recurrence babbling; 3) agreeable DC part dismissal; 4) practically identical execution with DSOGI based arrangement partition utilizing estimated voltage; 5) prescient capacity to remunerate one-advance postponement in prescient control. FCS-MPPC is executed dependent on SMGVO and tried on a two-level PWM rectifier to check the viability of the control framework. Test results demonstrate that FPSC and FNSC can be precisely assessed and isolated. The dynamic execution of SMGVO amid voltage droop is like that of DSOGI. The executed voltage sensorless FCSMPPC exhibits quick unique reactions which can follow control reference rapidly. Coordinate begin without starting information of lattice voltage is conceivable because of quick merging rate of SMGVO and high direction transfer speed of FCS-MPPC.


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