PWM FOR MINIMIZING THE SWITCHING FREQUENCY

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 9, Issue 11, November 2018, pp , Article ID: IJCIET_09_ Available online at aeme.com/ijciet/issues.asp?jtype=ijciet&vtype= =9&IType=11 ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed THREE PHASE MULTILEVEL PULSE WIDTH MODULATION PWM FOR MINIMIZING THE LOSSES OF SWITCHING FREQUENCY Al-Furat ABSTRACT The pulse width modulation is used to decreasing the consumptionn of power. The main drawbacks of conventional two level pulse width modulation PWM is that it causes high switching losses which increase time delay, complexity with nonlinear of system, and increase the variation of frequency which lead to instability of system. In this paper, the multilevel PWM is proposed to enhance the system performance and to remove the disadvantagess of traditional PWM. Also, fast Fourier transform FFT is also applied to produce the total harmonic distortion THD for system. The simulations design is built by Matlab toolbox and the achieved results show the excellent performance of system with multilevel PWM. Keywords: multilevel PWM, two level PWM, Fast Fourier transform FFT, Total harmonic distortion. Cite this Article: Amal M. A. Kadhim, Three Phase Multilevel Pulse width Modulation PWM For Minimizing The Losses of Switching Frequency, International Journal of Civil Engineering and Technology (IJCIET) 9(11), 2018, pp IET/issues.asp?JType=IJCIET&VType=9&ITy ype=11 1. INTRODUCTION Amal M. A. Kadhim Technical Institute of Babylon, Al-Awsat Technical University, Kufa, Iraq The PWM is widely used in power system to controlling the quantity of power supplying to the load without any dissipated power. The PWM was applied to enhance the drive of induction motor and the direct of current control respectively [1] [2]. New technique of space vector SVPWM for close loop control and sensorless of load voltage and current are reported by [3] [4]. The boost PWM was usefulfor decreasing the losses of system and to modify the voltage source control [5] [6] [7] [8]. The PWM was proposed for many researches to improve the stability of nonlinear system and controlling the power consumption by the load [9] [10] [11]

2 Three Phase Multilevel Pulse width Modulation PWM For Minimizing The Losses of Switching Frequency 2. RESULTS AND DISCUSSION A multilevel PWM has numerous benefits as compare with classical PWM that it produce load voltage and current with free of distortion and it operates with low switching frequency. The figure 1 and 2 shows the output voltage at the multilevel PWM and two level PWM which equal 400V but the voltage of multilevel is more synchronous as compare the two level. Figure 1 output voltage of multilevel PWM Figure 2 comparison of voltage The THD is produce by FFT which is equal to 36.8% in multilevel PWM, but in two level PWM the THD is 85.8% which mean that the output voltage waveform hashigh distortion with high switching losses in two level PWMas shown in figure 3, and editor@iaeme.com

3 Amal M. A. Kadhim Figure 3 THD in multilevel PWM Figure 4 THD in two level PWM The load voltage of proposed method is free of ripple without distortion as compare with two level PWM as shown in figure 5. Figure 5 comparison of load voltage editor@iaeme.com

4 Three Phase Multilevel Pulse width Modulation PWM For Minimizing The Losses of Switching Frequency The THD for load voltage in the proposed method is 0.93% while the value of THD in two level PWM is 3.98% as appeared in figures 6, and 7. Therefore, the system with low THD has good performance with high efficiency. Figure 6 THD at load voltage for proposed method Figure 7 THD at load voltage for conventional method 3. CONCLUSION The proposed multilevel PWM was improved the stability of system with low losses power. From the mentioned results, the system with suggested multilevel PWM is free of distortion, has high accuracy with fast response, and has the ability over the two level PWM. Inaddition, the low value of THD refer to good performance with high efficiency editor@iaeme.com

5 Amal M. A. Kadhim REFERENCES [1] F. Fleming and M. Krishnamurthy, Influence of DC-Link Fluctuations on ThreePhase Induction Motor Drives, IEEE Conference on Vehicle Power and Propulsion, 2009, pp [2] Wang Xu, Huang Kaizheng, Simulation of Three-phase Voltage Source PWM Rectifier Based on Direct Current Control", IEEE conference Congress on Image and Signal Processing, 2008, Vol. 5, pp [3] Viraj Selarka1, Prem Shah, Close Loop Control of Three Phase Active Front End Converter using SVPWM Technique", IEEE International Conference on Electrical Power and Energy Systems, 2016 [4] Z. Zhou P.J. Unsworth, Design and analysis of a feedforward control scheme for a threephase voltage source pulse width modulation rectifier using sensorless load current signal", IET Power Electronics,2009. [5] SrikanthanSridharan and Philip T. Krein, Minimization of System-Level Losses in VSI- Based Induction Motor Drives: Offline Strategies", IEEE Transactions on Industry Applications, Vol. 53, NO. 2, 2017, pp [6] Sylvain LECHAT SANJUAN, Voltage Oriented Control of ThreePhase Boost PWM Converters", CHALMERS UNIVERSITY OF TECHNOLOGY Gteborg, Sweden,2010. [7] Praveen Joseph, Jaison Mathew et.al, Review of current control strategies for a vector Controlled ThreePhase UPF Rectifier", IEEE International Conference on Power, Instrumentation, Control and Computing (PICC),2015 [8] Haoran Shi, Wei Xu, Chenghua Fu and Yao Yang et.al, Research on Three-phase Voltage Type PWM Rectifier System Based on SVPWM Control", Research Journal of Applied Sciences, Engineering and Technology, 5(12) , 2013 [9] Xiao-Qiang, Wei-Yang, He-Rong, Phase locked loop and synchronization methods for grid interfaced converters A Review", PrzegldElektrotechniczny, ISSN , R.87,4/2011 [10] L. G. B. Rolim, D. Rodrigues da Costa, M. Aredes, "Analysis and software implementation of a robust synchronizing PLL based on the pq theory", IEEE Transactions on Industrial Electronics,Vol. 53, No. 6, December 2006 [11] IEEE Standard IEEE Recommended Practices and Requirements for Harmonic Control In Electrical Power Systems editor@iaeme.com