3y ago

37 Views

3 Downloads

593.06 KB

6 Pages

Transcription

March 2019 IJIRT Volume 5 Issue 10 ISSN: 2349-6002Harmonics analysis of Sinusoidal PWM and Thirdharmonic injection PWM controlled Voltage sourceinverterMohd Junaid Mansoori1 , Mr. Prakash Bahrani21M.tech Scholar, Dept. of Electrical engineering, Aravali Institute of Technical Studies, Udaipur, India2Associate Professor, Department of Electrical engineering, Aravali Institute of Technical Studies,Udaipur, IndiaAbstract- The sinusoidal Pulse Width Modulation(S PWM) technique is one of the most popular PWMtechnique for controlling output and harmonicreduction of inverter. Recent developments in powerelectronics and semiconductor technology have lead useof higher carrier frequency in PWM modulationtechniques. In the presented work voltage sourceinverter is connected to the RL load with LC filter. TwoPWM techniques have been used to operate voltagesource inverter are sinusoidal(S PWM) PWM and thirdharmonic injection(THIPWM) PWM. The simulationresult shows THIPWM has better performance whencompared to S PWM Both techniques are shown withMATLAB simulink and compared in terms of THD.Index Terms- S PWM, THD, Voltage source inverter,carrier frequency, third harmonic injection PWM.1. INTRODUCTIONInverter converts input DC voltage into a.c. outputvoltage. Three phase inverters are normally used forhigh power applications. The applications of invertersinclude uninterrupted power supply (UPS), adjustablespeed drives, a.c. motor speed controllers etc.Voltage source inverter isThese considered parameters are varied to get desiredlow harmonics output. In this paper generated bycomparing reference sine wave and triangular wave.Sinusoidal PWM and third harmonic injection PWMtechniques are considered to operate VSI. They arecompared in terms of THD.2. CONTROL TECHNIQUESVarious PWM control strategies have been developedin the past two decades [2] To obtain variation ofIJIRT 147628output voltage and PWM control strategies such asSinusoidal pulse width modulation (SPWM),Thirdharmonic pulse width modulation (THPWM), Spacevector pulse width modulation(SVPWM) and 60 PWM are most commonly used for three phaseinverters. SPWM is simplest of all the above PWMtechniques.]. The required signals for gates ofinverter are generated by comparing reference sinewave and triangular carrier signal in SPWMtechnique. In 1975 Buja developed THPWMtechnique. THPWM is implemented in same manneras SPWM the difference is that reference a.c.waveform is not sinusoidal but consists of bothfundamental component and third harmoniccomponent[1],[4]. The advantages of PWMtechniques are that they are easy to implement andcontrol, reduces lower order harmonics [5]. SPWMand THPWM techniques are analyzed and comparedin terms of harmonics.Various PWM control strategies have been developedin the past decades [2].To obtain variation of outputvoltage and modulation PWM control strategies suchas Sinusoidal pulse width modulation (SPWM),Thirdharmonic pulse width (THPWM), Space vector pulsewidth modulation(SVPWM) and 60 PWM are mostcommonly used for three phase inverters. SPWM issimplest of all the above PWM techniques. Therequired signals for gates of inverter are2.1 Sinusoidal PWMThree sinusoidal modulating signals (V m) at lowfrequency but displaced from each other by 120 arecompared with a high frequency triangular carriersignal (V r). The resulting switching signals fromeach comparator are used to drive the inverterINTERNATIONAL JO URNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY1

March 2019 IJIRT Volume 5 Issue 10 ISSN: 2349-6002respective switches. The harmonic content in theconverter output waveform is chosen as theperformance criterion and it is desired to minimizefor proper operation. The frequency of referencesignal determines the inverter output frequency &litude of reference signal controls the modulationindex. The harmonic distortion of SPWM is higherthan other switching schemes especially at highmodulating index. Switching losses are also high inSPWM.Fig-2.2 Sinusoidal pulse width modulation2.2 Third harmonic injection PWMIn order to improve the inverters performance thirdharmonic injection PWM (THIPWM) technique wasdeveloped. THIPWM is improved sinusoidal PWMtechnique which adds a third order harmonic contentinto sinusoidal reference signal (V r) of fundamentalfrequency. The resultant waveform is compared withthe high frequency triangular carrier waveform. Thecomparator output generates signal pulses to triggerswitches of the inverter exactly as in SPWM inverter.Amplitude of third harmonic signal is 1/6 ofsinusoidal reference signal. Addition of thirdharmonic to sinusoidal reference leads to 15.5%increase in the utilization rate of the DC voltage. Thecomparator output is used for controlling the inverterswitches exactly as in SPWM inverter. The referencesignal is composed of fundamental and thirdharmonic frequency components as followingequations.IJIRT 147628Fig-3.1 Third harmonic injection PWMFig-3.3 Third harmonic injection PWM modulatingsignal3. AMPLITUDE MODULATION INDEXIt is ratio of amplitude of reference signal to thecarrier signal. 4. RESULTSPresented THD ANALYSIS OF VSI with sinusoidalPWM and third harmonic injection PWM.MATLAB simulation parameters1. Switching frequency(fc) 2 KHz to 18 KHz2. Fundamental frequency(f) 50 Hz3. Modulation index(Ma) 0.54. RL load 2 KW5. DC input voltage 700 VAS presented below simulation results of VSI atdifferent carrier frequency (fc) and Modulation indexis 0.5 at both PWM techniques.(a) VSI outputs at fc 2 KHzINTERNATIONAL JO URNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY2

March 2019 IJIRT Volume 5 Issue 10 ISSN: 2349-6002Fig.4.1 Output voltage of VSI using sinus oidal PWMat carrier frequency (f c) 2 KHzFig.4.2 Output current of VSI using sinusoidal PWMat carrier frequency ( ) 2 KHzFig.4.3 Output voltage of VSI using third harmonicinjection PWM at carrier frequency ( ) 2 KHzFig.4.4 Output current of VSI using third harmonicinjection PWM at carrier frequenc ( ) 2 KHzFig.4.5 FFT analysis of output current of VSI usingsinusoidal PWMFig.4.6 FFT analysis of output current of VSI usingthird harmonic injection PWM(b) VSI outputs at fc 8 KHzFig.4.7 Output voltage of VSI using sinusoidal PWMat carrier frequency ( ) 8 KHzFig.4.8 Output current of VSI using sinusoidal PWMat carrier frequency ( ) 8 KHzFig.4.9 Output voltage of VSI using third harmonicinjection PWM at carrier frequency ( ) 8 KHzFig.4.10 Output current of VSI using third harmonicinjection PWM at carrier frequency( ) 8KHzFig.4.11 FFT analysis of output current of VSI usingsinusoidal PWMIJIRT 147628INTERNATIONAL JO URNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY3

March 2019 IJIRT Volume 5 Issue 10 ISSN: 2349-6002Fig.4.12 FFT analysis of output current of VSI usingthird harmonic injection PWM(c) VSI outputs at fc 12 KHzFig.4.13 Output voltage of VSI using sinusoidalPWM at carrier frequency ( ) 12 KHzFig.4.17 FFT analysis of output current of VSI usingsinusoidal PWMFig.4.18 FFT analysis of output current of VSI usingthird harmonic injection PWM(d) VSI outputs at fc 18 KHzFig.4.14 Output current of VSI using sinusoidalPWM at carrier frequency ( ) 12 KHzFig.4.19 Output voltage of VSI using sinusoidalPWM at carrier frequency ( ) 18 KHzFig.4.15 Output voltage of VSI using third harmonicinjection PWM at carrier frequency( ) 12KHzFig.4.20 Output current of VSI using sinusoidalPWM at carrier frequency ( ) 18 KHzFig.4.16 Output current of VSI using third harmonicinjection PWM at carrier frequency ( 12 KHzFig.4.21 Output voltage of VSI using third harmonicinjection PWM at carrier frequency ( ) 18 KHzIJIRT 147628INTERNATIONAL JO URNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY4

March 2019 IJIRT Volume 5 Issue 10 ISSN: 2349-6002frequency from low to high value we can minimizethe THD of phase currents.REFERENCESFig.4.22 Output current of VSI using third harmonicinjection PWM at carrier frequency ( ) 18 KHzFig.4.23 FFT analysis of output current of VSI usingsinusoidal PWMFig.4.24 FFT analysis of output current of VSI usingthird harmonic injection PWM5.CONCLUSIONA three phase VSI has been implemented withSPWM and THPWM control strategies. We havedone MATLAB simulink model and FFT analysis atdifferent carrier frequency values. FFT Analysis ofVSI output current THD is done at carrierfrequencies from 2KHz to 18KHz and modulationindex is 0.5. From simulation results proved that withincreasing carrier frequency THD is decreasing inboth techniques for the output current. It is concludedthat THIPWM technique is giving lesser THD ofthree phase inverter output current when compared toSPWM technique with increasing carrier frequency.THIPWM is providing better quality output thanSPWM. It has clearly shown that by varying carrierIJIRT 147628[1] Muhammad H. Rashid, “Power Electronics Circuits, Devices and Applications” PearsonEducation Incorporated, 2005.[2] R.K. Pongiannan, and N. Yadaiah, “FPGABased Three Phase Sinusoidal PWM e on Electrical Energy Systems), pp.34-39, 2011.[3] J.Y. Lee, and Y.Y. Sun, “A New SPWM Inverterwith Minimum Filter Requirement, InternationalJournal of Electronics, Vol. 64, No. 5, pp. 815826, 1988.[4] Md Mubashwar Hasan, A. Abu-Siada, “A ThreePhase Symmetrical DC-Link Multilevel Inverterwith Reduced Number of DC Sources” IEEETransactions on Power electronic 2017.[5] K. Ma, F. Blaabjerg, and M. Liserre, “Thermalanalysis of multilevel grid side converters for 10mw wind turbines under low voltage ridethrough”, IEEE Trans. Ind. Appl., vol. 49, no. 2,pp. 909–921, Mar./Apr. 2013.[6] J. Miret, M. Castilla, A. Camacho, L. Vicuna, and J. Matas, “Control scheme for photovoltaicthree-phase inverters to minimize peak cur-rentsduring unbalanced grid-voltage sags,” IEEETrans. Power Electron., vol. 27, no. 10, pp.4262–4271, Oct. 2012.[7] S. Sharma and B. Singh, “Performance ofvoltage and frequency controller in isolated windpower generation for a three-phase four-wiresystem,” IEEE Trans. Power Electron., vol. 26,no. 12, pp. 3443–3452, Dec.2011.[8] Noel Richard Merritt and Chandan Chakrabortyand Prabodh Bajpai, “ New Voltage ControlStrategies for VSC based DG Units in anUnbalanced Microgrid,”, IEEE Transactions onSustainable Energy Vol. 8, no. 3, pp. 1127-1139January 13 2017.[9] P.Rodriguez and R. Teodorescu and F.Blaabjerg, “A stationary reference frame gridsynchronization system for three-phase gridconnected power converters under adverse gridconditions,” IEEE Transactions on PowerINTERNATIONAL JO URNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY5

March 2019 IJIRT Volume 5 Issue 10 ISSN: 2349-6002Electronics, Vol. 27, no. 1, pp. 99–112, January2012.[10] F. Gonzalez-Espin, G. Garcera, Ivan Patrao “Anadaptive control system for three-phasephotovoltaic inverters working in a polluted andvariable frequency electric grid”,IEEETransactions on Power electronics, Vol. 27, no.10, pp. 4248–4261, October 2012.[11] Ke Ma and Marco Liserre ” Operating andLoading Conditions of a Three-Level NeutralPoint-Clamped Wind Power Converter UnderVarious Grid Faults”, IEEE Transaction onindustry application Vol. 50, no. 1, pp. 520-530,February 2014.[12] A. Luna, J. Hermoso, R.Teodorescu, and F.Blaabjerg and P. Rodriguez,“ Grid VoltageSynchronization for Distributed GenerationSystems under Grid Fault Conditions” , IEEETransaction on Industry Applications Vol. 51,no. 4, pp.3414-3425, September 2015.[13] Javier Chivite-Zabalza, Pedro Izurza-Moreno,and Miguel Angel Rodriguez,” VoltageBalancing control in 3-Level Neutral-PointClamped Inverters Using Triangular CarrierPWM Modulation for FACTS Applications”,IEEE Transaction on Power electronics, Vol. 28,no. 10, pp. 4473-4484, October 2013.[14] Abdullah S. Bubshait, Ali Mortezaei, Marcelo G.Simoes, “Power quality enhancement for a gridconnected wind turbine energy system”, IEEETransaction on industry application Vol. 53, no.3, pp. 2495-2505, 2017.[15] J. Amini and M. Moallem, “ A Fault-Diagnosisand Fault-Tolerant Control Scheme for ions on industrial electronics, Vol. 64,no.3, pp. 1818-1826, July 2016.[16] Narsa Reddy Tummuru, Student Member, IEEE,Mahesh K. Mishra, Senior Member, IEEE, “AnImproved Current Controller for Grid ConnectedVoltage Source Converter in MicrogridApplications”, IEEE TransactionsonSustainable energy Vol. 6 no.2, pp. 595-605,April 2015.IJIRT 147628INTERNATIONAL JO URNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY6

that THIPWM technique is giving lesser THD of three phase inverter output current when compared to SPWM technique with increasing carrier frequency. THIPWM is providing better quality output than SPWM. It has clearly shown that by varying carrier frequency from low

Related Documents: