**ABSTRACT:**

At present, virtual flux voltage oriented control strategy is one of the widely used control strategies without grid voltage sensor. To solve the dc bias resulting from voltage vector integration in vector calculation of virtual flux and further avoid the steady state error. This paper presented a virtual flux observer with negative feedback resonant filter based on virtual flux principle. And is also proposed a delay compensation algorithm to solve the delay of virtual flux. In addition, the paper has brought forth the control system diagram of P WM rectifier without grid voltage sensor . Then, simulation system platform simulates the rectifier. Eventually, the analysis of simulation results verified the correctness and feasibility of the proposed algorithm.

**Keywords**:

- Virtual flux voltage
- resonant filter
- P WM rectifier
- Phase locked loop
- Harmonics analysis

**BLOCK DIAGRAM:**

Fig.1 The diagram of control system of P WM rectifier without grid voltage sensor based on virtual Flux.

**EXPECTED SIMULATION RESULTS: **

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Fig. 2 DC Side Voltage and AC Side Current.

** **Fig. 3 Harmonic Analysis of A Phase Current.

** **Fig. 4 The Output Angle of Phase Locked Loop and that of Virtual Flux During Uncontrolled P WM Rectifier

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Fig. 5 The Output Angle of Phase Locked Loop and that of Virtual Flux During Controlled Rectifier.

** **Fig.6 The Output Angle of Phase Locked Loop and that of Virtual Flux During Uncontrolled Rectifier after Compensation.

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Fig.7 The Output Angle of Phase Locked Loop and that of Virtual Flux During Controlled Rectifier after Compensation.

**CONCLUSION:**

This paper analyzed the Mathematical model of virtual flux algorithm. And proposed the virtual flux observer with negative feedback resonant filter. The simulation results show that the proposed virtual flux observer can realize flux estimation without steady state error and it has better dynamic characteristics than series algorithm of dual low pass filter. Furthermore, adjusted the relevant parameters of the observer. Eventually, brought forward a delay compensation algorithm to solve the delay of virtual flux, which can effectively compensate the error caused by system delay to flux observation. In this paper, the aging of electric reactor is not taken into account. The estimated value of virtual flux is bounded to change with the change of inductance.

**REFERENCES:**

[1] Ch u an-j in Zhang, Y i Tang e t a l.,“A Novel Virtual Space Vector Modulation Strategy for the Neutral-Point Potential Comprehensive Balance of Neutral-Point-Clamped Converters,” *Journal of Power Electronics, Vol.16, no.3, May. 2016, pp.946-959. *

[2] Hui Zhang, Ch u an-d a Sun e t a l.,“Voltage Vector Error Fault Diagnosis for Open-Circuit Faults of Three-Phase Four-Wire Active Power Filters ,” *IEEE Trans. Power Electron, vol. 32, no.3, pp.2215-2226, March, 2017. *

[3] S. Er en, M. Pah l e v a nine z had, A. Ba k h s ha i, and P. Jain, “Grid-connected voltage source invert er for renewable energy conversion system with sensor less current control, ” *in Proc. 25th Ann u. IEEE AP EC, 2010,vol. 1, pp. 768-772.*

[4] Hung-Chi Chen, Che Y u Lu, “Digital Current Sensor less Control for Dual-Boost Half-Bridge PFC Converter with Natural Capacitor Voltage Balancing,” *IEEE Trans. Power Electron, pp.768-772,M c r ch. 2016.*

[5] Kr i sh an Kan t 1, S a b ha Ra j Ar ya, “Current Sensor less Control Algorithm of D STAT COM for Power Quality Improvement,” *in Proc. An nu. IEEE IND I CON, Dec.2015, pp.2325-9418.*

###### References

[6] J. Gonzalez Nor n i e l la, J. M. Can o, G. A. Or ca j o, C. H. Rojas, J. F. P e d r yes, M. F. Cabanas, e t a l., “Improving the Dynamics of Virtual-Flux-Based Control of Three-Phase Active Rectifiers, ” IEEE Trans. Industrial Electron., vol. 61, no.2, pp.177-187, Jan. 2014.

[7] M. B. K e t z er and C. B. Jacob in a, “Nonlinear virtual flux oriented control for sensor less active filters,” in Proc. Power Electronics Conference, Oct. 2013, pp.393-398.

[8] M. Ra z a l i, M. A. Rah man, and N. A. Ra him, “Real-time implementation of d-q control for grid connected three phase voltage source converter,” in Proc. 40th Annual, IEEE IE CON, Oct./Nov. 2014, pp.1733-1739.

[9] M. B. K e t z er and C. B. Jacob in a, “Sensor less Control Technique for P WM Rectifiers With Voltage Disturbance Rejection and Adaptive Power Factor, ” IEEE Trans. Industrial Electron., vol. 62, no.2,pp.1140-1151, Feb. 2015.