Current Decoupling Control for the Three-level PWM Rectifier with a Low Switching Frequency

Title & Authors
Current Decoupling Control for the Three-level PWM Rectifier with a Low Switching Frequency
Yuan, Qing-Qing; Xia, Kun;

Abstract
Three-level PWM rectifiers applied in medium voltage applications usually operate at low switching frequency to keep the dynamic losses under permitted level. However, low switching frequency brings a heavy cross-coupling between the current components $\small{i_d}$ and $\small{i_q}$ with a poor dynamic system performance and a harmonic distortion in the grid-connecting current. To overcome these problems, a mathematical model based on complex variables of the three-level voltage source PWM rectifier is firstly established, and the reasons of above issues resulted from low switching frequency have been analyzed using modern control theory. Then, a novel control strategy suitable for the current decoupling control based on the complex variables for $\small{i_d}$ and $\small{i_q}$ is designed here. The comparisons between this kind of control strategy and the normal PI method have been carried out. MATLAB and experimental results are given in detail.
Keywords
Three-level PWM rectifier;Low switching frequency;Cross-coupling;Complex current controller;
Language
English
Cited by
References
1.
J.A. Pontt et. al., “Network-friendly low-switching frequency multipulse high-power three-level PWM rectifier,” IEEE Transactions on Industrial Electronics, Vol.56, No.4, pp. 1254-1262, April.2009.

2.
H. Akagi et. al., “A new power line conditioner for harmonic compensation in power system,” IEEE Transactions on Power Delivery, Vol.10, No.3, pp.1570-1575, July.1995.

3.
Z. C. Zhang et. al., “Multimodular current-source SPWM converters for superconducting a magnetic energy storage system,” IEEE Transactions on Power Electronics, Vol.8, No.3, pp.250-255, July.1993.

4.
C. Z. Javier et.al., “A large power, low switching frequency voltage source converter for FACTS applications with low effects on the transmission line,” IEEE Transactions on Power Electronics, Vol. 27, No.12, pp.4868-4879, Dec.2012.

5.
L. Cristian et.al., “Frequency response analysis of current controllers for selective harmonic compensation in active power filters,” IEEE Transactions on Industrial Electronics, Vol. 56, No. 2, pp. 337-347, Feb. 2009.

6.
X. Q. Li et. al., “Stability analysis of grid-connected inverters with an LCL filter considering grid impedance,” Journal of Power Electronics, Vol. 13, No. 5, pp. 896-908, Sept.2013.

7.
N. Oikonmou. Control of medium-voltage drives at very low switching frequency, Logos Verlag, 2008.

8.
L.G. Franquelo et.al., “New trends and topologies for high power industrial applications: The multilevel converters solution,” International Conference on Power Engineering, Energy and Electrical Drives, pp.1-6, 2009.

9.
A.G. Siemens. “Power semiconductors: for medium voltage converters-an overview,” 13th European Conference on Power Electronics and Applications, pp.1-14, 2009.

10.
P. B. Rolando et.al., “Complex state variables modeling and nonlinear control of PWM voltage and current source rectifiers,” 28th Annual Conference of the IEEE Industrial Electronics Society, pp.187-192, 2002.

11.
J. Holtz et.al., “Design of fast and robust current regulators for high-power drives based on complex state variables,” IEEE Transactions on Industry Applications, Vol. 40, No. 5, pp. 1388-1397, Sept.-Oct.2004.

12.
J. Holtz et.al., “Estimation of the Fundamental Current in Low-Switching-Frequency High Dynamic Medium-Voltage Drives,” IEEE Transactions on Industry Applications, Vol. 44, No. 5, pp. 1597-1605, Sept. -Oct. 2008.

13.
J. S. Liang et.al., “A three-phase PWM AC-DC converter with low switching frequency and high power factor using DSP-based repetitive control technique,” 29th Annual IEEE Power Electronics Specialists Conferences, pp.517-523, 1998.

14.
S. Kouro et.al., “Model predictive control - a simple and powerful method to control power converters,” IEEE Transactions on Industrial Electronics, Vol. 56, No. 6, pp. 1826-1838, June. 2009.

15.
A. A. Rockhill et.al., “Grid-Filter Design for a Multi-megawatt Medium-Voltage Voltage-Source Inverter,” IEEE Transactions on Industry Applications, Vol. 58, No. 4, pp. 1205-1217, April. 2011.

16.
J. Holtz. “The representation of AC machine dynamics by complex signal flow graphs,” IEEE Transactions on Industrial Electronics, Vol. 42, No. 3, pp.263-271, Jun. 1995.

17.
B. S. Chen, Automation control system for power drives, China Machine Press, chap. 8, 2003.