Real time implementation of unity power factor correction converter based on fuzzy logic

 Abstract

In this paper an analysis and real time implementation of unity power factor correction converter (PFC) based on fuzzy logic controller is studied. A single phase AC–DC boost converter is realized to replace the conventional diode bridge rectifier. Fuzzy logic and hysteresis control techniques is implemented to improve the performance of the boost converter. The fuzzy controller is applied to DC voltage loop circuit to get better performance. The current loop is being controlled by using a PI, and hysteresis controllers. The robustness of the controller is verified via MATLAB/Simulink, the results show that the fuzzy controller gives well controller. An experiment test is implemented via a test bench based on dSPACE 1103. The experimental results show that the proposed controller enhanced the performance of the converter under different parameters variations.

Keywords

1.      Power factor correction (PFC)

2.       PLL

3.       Fuzzy logic controller (FLC)

4.       Hysteresis controller

5.       DSPACE 1103

Software: MATLAB/SIMULINK

Circuit Diagram:

Fig. 1. Single phase PFC boost converter control system

Expected Simulation Results

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Fig.2. Diode Bridge input current

Fig.3. Line Current and its harmonic spectrum using the fuzzy controller for

DC bus

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Fig.4. DC bus voltage based on fuzzy controller

Fig.5. PFC input current

Conclusion:

In this paper, a single-phase PFC converter DC voltage loop has been analysed. The fuzzy logic controller technique is implemented to improve the performance of the PFC converter, it is robust and efficient. Matlab/Simulink has been used to simulate the proposed techniques with successful result, the dSPACE 1103 have been used to implement the fuzzy controller in real-time. Simulation results have been presented and confirmed by the real time tests; in the same time, high efficiency is obtained. The proposed controller applied to the unity power factor give better results, a reduced harmonic distortion, and robustness control during parameter variations.

References

[1] M. Malinowski, M. Jasinski, M.P. Kazmierkowski, “Simple direct power control of three-phase PWM rectifier using space-vector modulation (DPCSVM)”, IEEE Transactions on Industrial Electronics (2004) 447–454

[2] Masashi O., Hirofumi M. “An AC/DC Converter with High Power Factor”, IEEE Transaction on Industrial Electronics, 2003, Vol 50, No. 2, pp. 356–361.

[3] Kessal A, Rahmani L, Gaubert JP, Mostefai M. “Analysis and design of an isolated single-phase power factor corrector with a fast regulation”. Electr Power Syst Res 2011; 81:1825–31.

[4] Guo L, Hung JY, Nelms RM. “Comparative evaluation of sliding mode fuzzy controller and PID controller for a boost converter.” Electr Power Syst Res 2011; 81:99–106.

[5] Kessal A, Rahmani L, Gaubert JP, Mostefai M. “Experimental design of a fuzzy controller for improving power factor of boost rectifier”. Int J Electron 2012;99 (12):1611–21.

A Solar Power Generation System With a Seven-Level Inverter

ABSTRACT:

 

This paper proposes a new solar power generation system, which is composed of a dc/dc power converter and a new seven-level inverter. The dc/dc power converter integrates a dc–dc boost converter and a transformer to convert the output voltage of the solar cell array into two independent voltage sources with multiple relationships. This new seven-level inverter is configured using a capacitor selection circuit and a full-bridge power converter, connected in cascade. The capacitor selection circuit converts the two output voltage sources of dc–dc power converter into a three-level dc voltage, and the full-bridge power converter further converts this three-level dc voltage into a seven-level ac voltage. In this way, the proposed solar power generation system generates a sinusoidal output current that is in phase with the utility voltage and is fed into the utility. The salient features of the proposed seven-level inverter are that only six power electronic switches are used, and only one power electronic switch is switched at high frequency at any time. A prototype is developed and tested to verify the performance of this proposed solar power generation system.

KEYWORDS:

 

1.      Grid-connected

2.      Multilevel inverter

3.      Pulse-width modulated (PWM) inverter

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Configuration of the proposed solar power generation system.

EXPECTED SIMULATION RESULTS:

Fig. 2. Simulation results of the proposed solar power generation system: (a) utility voltage, (b) negative terminal voltage for adding the symmetric filter inductor, and (c) negative terminal voltage for adding the symmetric filter inductor and the extra filter C_f –R_f –C_f .

Fig. 3. Experimental results for the ac side of the seven-level inverter:

(a) utility voltage, (b) output voltage of seven-level inverter, and (c) output

current of the seven-level inverter

Fig. 4. Experimental results for the dc side of the seven-level inverter:

(a) utility voltage, (b) voltage of capacitor C2, (c) voltage of capacitor C1,

and (d) output voltage of the capacitor selection circuit.

Fig. 5. Experimental results of the dc–dc power converter: (a) ripple current of inductor, (b) ripple voltage of capacitor C2, and (c) ripple voltage of capacitor C1.

Fig. 6. Output power scan of the solar cell array.

Fig. 7. Experimental results for the MPPT performance of the proposed solar power generation system.

CONCLUSION:

This paper proposes a solar power generation system to convert the dc energy generated by a solar cell array into ac energy that is fed into the utility. The proposed solar power generation system is composed of a dc–dc power converter and a seven level inverter. The seven-level inverter contains only six power electronic switches, which simplifies the circuit configuration. Furthermore, only one power electronic switch is switched at high frequency at any time to generate the seven-level output voltage. This reduces the switching power loss and improves the power efficiency. The voltages of the two dc capacitors in the proposed seven-level inverter are balanced automatically, so the control circuit is simplified. Experimental results show that the proposed solar power generation system generates a seven-level output voltage and outputs a sinusoidal current that is in phase with the utility voltage, yielding a power factor of unity. In addition, the proposed solar power generation system can effectively trace the maximum power of solar cell array.

REFERENCES:

[1] R. A. Mastromauro, M. Liserre, and A. Dell’Aquila, “Control issues in single-stage photovoltaic systems: MPPT, current and voltage control,” IEEE Trans. Ind. Informat., vol. 8, no. 2, pp. 241–254, May. 2012.

[2] Z. Zhao, M. Xu,Q. Chen, J. S. Jason Lai, andY. H. Cho, “Derivation, analysis, and implementation of a boost–buck converter-based high-efficiency pv inverter,” IEEE Trans. Power Electron., vol. 27, no. 3, pp. 1304–1313, Mar. 2012.

[3] M. Hanif, M. Basu, and K. Gaughan, “Understanding the operation of a Z-source inverter for photovoltaic application with a design example,” IET Power Electron., vol. 4, no. 3, pp. 278–287, 2011.

[4] J.-M. Shen, H. L. Jou, and J. C. Wu, “Novel transformer-less grid connected power converter with negative grounding for photovoltaic generation system,” IEEE Trans. Power Electron., vol. 27, no. 4, pp. 1818– 1829, Apr. 2012.

[5] N. Mohan, T. M. Undeland, and W. P. Robbins, Power Electronics Converters, Applications and Design, Media Enhanced 3rd ed. New York, NY, USA: Wiley, 2003.

Hybrid Active Filter with Variable Conductance for Harmonic Resonance Suppression in Industrial Power Systems

ABSTRACT:

Unintentional series and/or parallel resonances, due to the tuned passive filter and the line inductance, may result in severe harmonic distortion in the industrial power system. This paper presents a hybrid active filter to suppress harmonic resonance and to reduce harmonic distortion. The proposed hybrid filter is operated as variable harmonic conductance according to the voltage total harmonic distortion; therefore, harmonic distortion can be reduced to an acceptable level in response to load change or parameter variation of the power system. Since the hybrid filter is composed of a seventh-tuned passive filter and an active filter in series connection, both dc voltage and kVA rating of the active filter are dramatically decreased compared with the pure shunt active filter. In real application, this feature is very attractive since the active power filter with fully power electronics is very expensive. A reasonable tradeoff between filtering performances and cost is to use the hybrid active filter. Design consideration are presented, and experimental results are provided to validate effectiveness of the proposed method. Furthermore, this paper discusses filtering performances on line impedance, line resistance, voltage unbalance, and capacitive filters.

KEYWORDS:

1.      Harmonic resonance

2.       Hybrid active filter

3.      Industrial power system

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Proposed HAFU in the industrial power system and its associated control. (a) Circuit diagram of the HAFU. (b) Control block diagram of the HAFU.

EXPECTED SIMULATION RESULTS:

             

Fig. 2. Line voltage e, source current i_s, load current i_L, and filter current i in the case of NL₁ initiated. X-axis: 5 ms/div. (a) HAFU is off. (b) HAFU is on.

Fig. 3. Line voltage e, source current i_s, load current i_L, and filter current i in the case of NL₂ initiated. X-axis: 5 ms/div. (a) HAFU is off. (b) HAFU is on.

Fig. 4. Transient response when the nonlinear load is increased at T. (a)Waveforms of v_dc, Voltage THD, G^*. X-axis: 100 ms/div; Y -axis: v_dc (V), G^* (1.21 p.u./div), and THD (1.25%/div). (b) Current waveforms.

Fig. 5. HAFU is off for single-phase nonlinear load. (a) Terminal voltage. (b) Source current. (c) Filter current. (d) Load current.

Fig. 6. HAFU is on for single-phase nonlinear load. (a) Terminal voltage. (b) Source current. (c) Filter current. (d) Load current.

CONCLUSION:

This paper presents a hybrid active filter to suppress harmonic resonances in industrial power systems. The proposed hybrid filter is composed of a seventh harmonic-tuned passive filter and an active filter in series connection at the secondary side of the distribution transformer. With the active filter part operating as variable harmonic conductance, the filtering performances of the passive filter can be significantly improved. Accordingly, the harmonic resonances can be avoided, and the harmonic distortion can be maintained inside an acceptable level in case of load changes and variations of line impedance of the power system. Experimental results verify the effectiveness of the proposed method. Extended discussions are summarized as follows.

• Large line inductance and large nonlinear load may result in severe voltage distortion. The conductance is increased to maintain distortion to an acceptable level.

• Line resistance may help reduce voltage distortion. The conductance is decreased accordingly.

• For low line impedance, THD^* should be reduced to enhance filtering performances. In this situation, measuring voltage distortion becomes a challenging issue.

• High-frequency resonances resulting from capacitive filters is possible to be suppressed by the proposed method.

• In case of unbalanced voltage, a band-rejected filter is needed to filter out second-order harmonics if the SRF is realized to extract voltage harmonics.

 REFERENCES:

 [1] R. H. Simpson, “Misapplication of power capacitors in distribution systems with nonlinear loads-three case histories,” IEEE Trans. Ind. Appl., vol. 41, no. 1, pp. 134–143, Jan./Feb. 2005.

[2] T. Dionise and V. Lorch, “Voltage distortion on an electrical distribution system,” IEEE Ind. Appl. Mag., vol. 16, no. 2, pp. 48–55, Mar./Apr. 2010.

[3] E. J. Currence, J. E. Plizga, and H. N. Nelson, “Harmonic resonance at a medium-sized industrial plant,” IEEE Trans. Ind. Appl., vol. 31, no. 4, pp. 682–690, Jul/Aug. 1995.

[4] C.-J. Wu et al., “Investigation and mitigation of harmonic amplification problems caused by single-tuned filters,” IEEE Trans. Power Del., vol. 13, no. 3, pp. 800–806, Jul. 1998.

[5] B. Singh, K. Al-Haddad, and A. Chandra, “A review of active filters for power quality improvement,” IEEE Trans. Ind. Electron., vol. 46, no. 5, pp. 960–971, Oct. 1999.