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.
.
EXPECTED SIMULATION RESULTS
Fig.
2. 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.
3. 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.
4. Current controller swithcing mechanism.
Fig.
6. 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.
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 higj-performance single-phase rectifier with
input power factor correction,” IEEE Transactions on Power Electronics,
vol. 11, no. 2, pp. 311–317, Mar. 1996.
