ABSTRACT
This paper
proposes an improved modulated carrier control with on-time doubler for the
single-phase shunt active power filter, which eliminates harmonic and reactive
currents drawn by nonlinear loads. This control method directly shapes the line
current to be sinusoidal and in phase with the grid voltage by generating a
modulated carrier signal with a resettable integrator, comparing the carrier
signal to the average line current and making duty ratio doubled. Since the
line current compared to the carrier signal is not the peak, but the average
value, dc-offset appeared at the conventional control methods based on
one-cycle control is effectively addressed. The proposed control technique
extirpates the harmonic and reactive currents and solves the dc-offset problem.
The operation principle and stability characteristic of the single-phase shunt
active power filter with the proposed control method are discussed, and
experimental results with laboratory prototype under various load conditions
verify its performance.
KEYWORDS
1.
Single-phase
shunt active power filter
2.
Modulated
carrier control
3.
Indirect
control
4.
One-cycle
control
5.
Harmonic and
reactive currents elimination
6.
Nonlinear
load.
SOFTWARE:
MATLAB/SIMULINK
CIRCUIT
DIAGRAM
Fig. 1.
Single-phase shunt active power filter with nonlinear load.
Fig. 2. Overall
control structure of the proposed control method with the shunt APF.
EXPECTED SIMULATION RESULTS
Fig. 3. Measured grid voltage, line
current, APF current and load current waveforms of the shunt APF system based
on the proposed control method at full load condition (vin : 200 V/div, iin
: 20 A/div, if : 20 A/div, i- L : 20 A/div).
Fig. 4. Measured
grid voltage, line current, APF current and load current waveforms of the shunt
APF system based on the proposed control method at half load condition (vin :
200 V/div, iin : 20 A/div, if : 20 A/div, iL : 20 A/div).
Fig. 5. Current
controller switching mechanism.
Fig. 6. Measured
dc-link voltage, line current, APF current and load current waveforms of the
shunt APF system in load transient from 800 W to 1600 W (vo : 100 V/div,
iin : 20 A/div, if : 20 A/div, iL : 20 A/div).
Fig. 7. Measured grid voltage, line
current, APF current and load current waveforms of the shunt APF system at 110
Vrms grid voltage. (vin : 100 V/div, iin : 10 A/div, if :
10 A/div, iL : 10 A/div) Under (a) 200 W, (b) 270 W, (c) 340 W, (d) 400
W load condition
Fig. 8. Power factors of the
nonlinear load system with and without the APF under various load conditions.
CONCLUSION
An improved
modulated carrier control for single-phase active power filter has been
proposed. The shunt APF with the proposed control method fulfills harmonic and
reactive current elimination at the line current by comparing the carrier
signal to the average line current and having the duty ratio doubled. On top of
that, the control method totally gets rid of the dc-offset problem arisen at
the conventional one based on one-cycle control and ameliorates the current
control loop stability without additional ramp signal. The operation principle
of power stage, the main control mechanism, and the stability characteristic of
the current control loop are analyzed in detail. Experimental results with the
shunt APF system under assorted conditions verify the performance of the
proposed control method in steady and transient states.
REFERENCES
[1]
Elham B. Makram, E.V. Subramaniam, Adly A.
Girgis, and Ray Catoe, “Hamonic filter design using actual recorded data,” IEEE
Transaction on Industrial Application, vol. 29, no. 6, pp. 1176-1183, Nov.
1993.
[2]
F. Z. Peng, “Harmonic sources and filtering
approaches,” IEEE Transaction on Industrial Application Magazine, vol.
7, no. 4, pp. 18-25, Jul. /Aug. 2001.
[3]
Czarnecki, L. S., Ginn, H. L., “The effect of
the design method on efficiency of resonant harmonic filters,” IEEE
Transactions on Power Delivery, vol. 20, no. 1, pp. 286-291, Jan. 2005.
[4]
Fakhralden A. Huliehel, Fred C. Lee, and Bo H.
Cho, “Small-signal modeling of the single-phase boost high power factor
converter with constant frequency control,” PESC’92 Record. 23rd annual IEEE
Power electronics Specialists Conference, 1992, vol.1, pp. 475 – 482.
[5]
R. Martinez, P. N. Enjeti, “A high-performance
single-phase rectifier with input power factor correction,” IEEE
Transactions on Power Electronics, vol. 11, no. 2, pp. 311–317, Mar. 1996.
