A Novel Multilevel Multi-Output Bidirectional Active Buck PFC Rectifier

 ABSTRACT:

This paper presents a new family of buck type PFC (power factor corrector) rectifiers that operates in CCM (continuous conduction mode) and generates multilevel voltage waveform at the input. Due to CCM operation, commonly used AC side capacitive filter and DC side inductive filter are removed from the proposed modified packed U-cell rectifier structure. Dual DC output terminals are provided to have a 5-level voltage waveform at the input points of the rectifier where it is supplied by a grid via a line inductor. Producing different voltage levels reduces the voltage harmonics which affects the grid current harmonic contents directly. Low switching frequency of the proposed rectifier is a distinguished characteristic among other buck type rectifiers that reduces switching losses and any high switching frequency related issues, significantly. The proposed transformer-less, reduced filter and multilevel rectifier topology has been investigated experimentally to validate the good dynamic performance in generating and regulating dual 125V DC outputs terminals as telecommunication boards feeders or industrial battery chargers under various situation including change in the loads and change in the in main grid voltage amplitude.

KEYWORDS:

1.      Packed U-Cell

2.      PUC5

3.      HPUC

4.      Buck PFC rectifier

5.      Multilevel converter

6.      Power quality

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1. Proposed HPUC five-level buck PFC rectifier

 EXPECTED SIMULATION RESULTS:

Fig. 2. Experimental results of the proposed HPUC rectifier connected to 120V RMS AC grid and supplying two DC loads at 125V DC. a) Output DC voltages regulated at 125V with grid side synchronised voltage and current b) DC loads currents with grid side synchronised voltage and current c) 5-Level voltage waveform at the input of the HPUC rectifier d) RMS and THD values of the AC side synchronised voltage and current waveforms

 

 

Fig. 3. Test results during 200% increase in Load1 from 53_ to 160_

Fig. 4. Test results during 50% decrease in Load2 from 80_ to 40_

Fig. 5. Supply voltage variation while the output DC voltages are regulated at 125V as buck mode of operation.

 

CONCLUSION:

 

In this paper a 5-level rectifier operating in buck mode has been proposed which is called HPUC as a slight modification to PUC multilevel converter. It has been demonstrated that the proposed rectifier can deceive the grid by generating maximum voltage level of 250V at AC side as boost mode while splitting this voltage value at its two output terminals to provide buck mode of operation with 125V DC useable for battery chargers or telecommunication boards’ feeder. Although it has more active switches than other buck rectifier topologies and some limitations on power balance between loads, overall system works in boost mode and CCM which results in removing bulky AC and DC filters that usually used in conventional buck PFC rectifiers. Moreover, generating multilevel waveform leads to reduced harmonic component of the voltage waveform and consequently the line current. It also aims at operating with low switching frequency and small line inductor that all in all characterizes low power losses and high efficiency of the HPUC rectifier. Comprehensive theoretical studies and simulations have been performed on power balancing issue of the HPUC rectifier. Full experimental results in steady state and during load and supply variation have been illustrated to prove the fact that HPUC topology can be a good candidate in a new family of buck bridgeless PFC rectifiers with acceptable performance. Future works can be devoted to developing robust and nonlinear controllers on the proposed rectifier topology.

REFERENCES:

[1] M. Mobarrez, M. G. Kashani, G. Chavan, and S. Bhattacharya, "A Novel Control Approach for Protection of Multi-Terminal VSC based HVDC Transmission System against DC Faults," in ECCE 2015- Energy Conversion Congress & Exposition, Canada, 2015, pp. 4208- 4213.

[2] IEEE, "IEEE Recommended Practice and Requirements for Harmonic Control in Electric Power Systems," in IEEE Std 519-2014 (Revision of IEEE Std 519-1992), ed, 2014, pp. 1-29.

[3] IEC, "Limits for Harmonic Current Emissions (Equipment Input Current_ 16A Per Phase)," in IEC 61000-3-2 (Ed. 3.2, 2009), ed, 1995.

[4] B. Singh, B. N. Singh, A. Chandra, K. Al-Haddad, A. Pandey, and D. P. Kothari, "A review of single-phase improved power quality ACDC converters," IEEE Trans. Ind. Electron., vol. 50, no. 5, pp. 962- 981, 2003.

[5] H. Choi, "Interleaved boundary conduction mode (BCM) buck power factor correction (PFC) converter," IEEE Trans. Power Electron., vol. 28, no. 6, pp. 2629-2634, 2013.