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, a
virtual flux observer with negative feedback resonant filter is presented in
this paper based on virtual flux principle and a delay compensation algorithm
is also proposed to solve the delay of virtual flux. In addition, the control
system diagram of PWM rectifier without grid voltage sensor is brought forth.
Then, simulation system and experimental platform are both established to
simulate and test the rectifier. Eventually, the correctness and feasibility of
the proposed algorithm are verified through the analysis of simulation and
experimental results.
KEYWORDS:
1. Virtual flux
2. Sensorless
3. PWM rectifier
SOFTWARE: MATLAB/SIMULINK
Fig.1
The diagram of control system of rectifier without grid voltage sensor based on
virtual Flux.
EXPECTED SIMULATION RESULTS:
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 Rectifier
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.
Fig.7
The Output Angle of Phase-Locked Loop and that of Virtual Flux During
Controlled Rectifier after Compensation.
CONCLUSION:
Mathematical
model of virtual flux algorithm is analyzed in this paper. The improvement is
made to the existing virtual flux observer, and then the virtual flux observer
with negative feedback resonant filter is proposed in this paper. The
simulation and experimental 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, relevant parameters of the observer are adjusted. Eventually, a
delay compensation algorithm is brought forward 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] Chuan-jin Zhang, Yi Tang et al.,“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, Chuan-da Sun et al.,“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. Eren, M. Pahlevaninezhad, A. Bakhshai, and P. Jain,
“Grid-connected voltage source inverter for renewable energy conversion system
with sensorless current control, ” in Proc. 25th Annu. IEEE APEC, 2010,vol.
1, pp. 768-772.
[4] Hung-Chi Chen,
Che Yu Lu, “Digital Current Sensorless Control for Dual-Boost Half-Bridge PFC
Converter with Natural Capacitor Voltage Balancing,” IEEE Trans. Power
Electron, pp.768-772,Mcrch. 2016.
[5] Krishan Kant1,
Sabha Raj Arya, “Current Sensorless Control Algorithm of DSTATCOM for Power
Quality Improvement,” in Proc. Annu. IEEE INDICON, Dec.2015, pp.2325-9418.
