Comparative Analysis of SVPWM and DSVPWM Control Techniques for a Single-Phase to Three- Phase Conversion System

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1 ISSN (Online): Index Copernicus alue (03): 6.4 Ipact Factor (03): Coparative Analysis of SPWM and DSPWM Control Techniques for a Single-Phase to Three- Phase Conversion Syste CH. Sridevi, I. Ravikiran Electrical Departent, GMRIT, GMRIT Capus, Raja, Andhra Pradesh, India Sridevi.swathi9999@gail.co Elextrical Departent, GMRIT, GMRIT Capus, Raja, Andhra Pradesh, India Ravikiran.i@grit.org Abstract: This paper presents a Single-phase to Three-phase drive syste with two parallel single-phase rectifiers, a three-phase inverter and an induction otor. It reduces the haronic distortion at the input converter side, rectifier switch currents, reduction in the input current processed by parallel connection of rectifiers and reduction of the output voltage processed by series connection of inverters. The pulse pattern for rectifier is generated through pulse width odulation (PWM) technique. The switching pulse for inverter is generated through Space vector pulse width odulation (SPWM) &Discontinuous space vector pulse width odulation (DSPWM) techniques and both the techniques are ipleented using MATLAB/SIMULINK and the response of the syste is observed for SPWM and DSPWM. Keywords: Power conversion, pulse width odulation (PWM), space vector PWM, discontinuous space vector PWM and THD.. Introduction A Single-phase syste has lower cost features copared to Three-phase syste in the power distribution syste. Due to the usage of three-phase otors (because of better perforance), it necessitates the conversion of Single-phase syste to Three-phase syste []. But the probles associated with this conversion syste are increased nuber of coponents, distortion and irregular distribution of power aong the switches of the converter, which ay give rise to power quality issues in source side and perforance issues in load side. An alternative topology as shown in Fig. studied, which reduces the rectifier switch-currents, haronic distortion at the input converter side and it shows iproveents in the fault tolerance characteristics []-[6]. By parallel connection of the rectifier, current processed at the input side reduces and reduction of the output voltage processed by series connection of inverter [7]. The developent of this paper is done by ipleenting space vector PWM control technique in continuous & discontinuous odes for three-phase inverter. Three-phase SPWM, increases the -bus utilization copared to PWM based on sine-triangle coparison technique[8] and DSPWM can effectively reduce the switching loss & output current ripple copare to SPWM[].. Control Technique for Rectifier The output voltage of the single-phase converter is controlled by pulse width odulation technique. Pulse width odulation (PWM) is a technique where the duty ratio of a pulsating wavefor is controlled by coparing reference Figure: Single-Phase to Three-Phase drive syste wave with carrier wave [8] (here triangular wave is considered as reference wave and signal is considered as carrier wave). The output voltage of the converter can be deterined in two steps. One, by considering only one pair of pulses, which are produced by coparing triangular wave with signal and if one pulse start at wt ends at wt and the next pulse start fro wt [5]. wt and ends at. Two, by joining the effects of all pairs olue 4 Issue 7, July 05 Paper ID: SUB Licensed Under Creative Coons Attribution CC BY

2 If th pulse starts at wt International Journal of Science and Research (IJSR) ISSN (Online): Index Copernicus alue (03): 6.4 Ipact Factor (03): and its width is, the average output voltage due to p nuber of pulses is found fro p [ p sin wtd( wt)] [cos cos( )] 3. Control Technique for Inverter The output voltage of the inverter can be controlled by ipleenting space vector PWM control technique either in continuous and discontinuous ode. 3. Space ector Pulse Width Modulation (SPWM) In the case of the neutral point of the load is isolated, neutral current does not exist and inverter line to line voltage is the only source to deterine the load current subcarrier frequency coponent. Thus, the coon ode voltage (CM) can be freely varied. In such applications, the injection of the zero sequence-signal to the reference waves significantly shifts the reference waves in vertical direction with respect to carrier wave, which iplies the average value of the inverter line to line voltage is not affected and it iproves the voltage linearity, haronic distortion and switching frequency characteristics [9]. One of the ethod to iprove the haronic distortion by injecting zero sequence signal is space vector pulse width odulation (SPWM). SPWM is an algorith for the control of pulse width odulation. It is used for the creation of ac wavefors; ost coonly to drive three-phase ac powered otors at varying speeds fro using ultiple class-d aplifiers. In three-phase SI, the carrier wave ay be triangular or sawtooth for each phase can be randoly selected. On the other hand, the carrier wave of one phase is phase shifted with respect to the carrier wave of another phase. Conventionally one coon carrier wave is used for all three phases due to its syetrical switching sequence which results in low haronic distortion and low switching losses. The circuit of the three-phase PWM inverter is shown in fig.. When the upper switch of the inverter is turned on(a, b, c value is ), then the corresponding lower switch is turned off(a, b, c value is 0). Then the three- phase inverter fors eight voltage vectors [7]. Out of these eight vectors, six vectors are non-zero vectors and two vectors are zero vectors. The output voltage of the inverter is calculated by using the following equations; Line to Line oltage ectors ab bc ca 0 Line to neutral oltage ector an bn cn a b c a b c By substituting voltage vectors in equations()&(), we can calculate the output voltage of the inverter and the voltages are shown in Table- [8]. Table: Switching pattern and output vectors oltageswitching vectors Line to neutral Line to line vectors voltage voltage a b c an bn cn ab bc ca /3 -/3 -/3 0-0 /3 /3 -/ /3 /3 -/ /3 /3 / /3 -/3 / /3 -/3 / (Note that the respective voltage should be ultiplied by ) These voltage vectors for a hexagon, which consists of 6 sectors spanning 60 0 each []. Consider the reference voltage vector ref with an angle α as shown in fig-3. () () Figure 3: Basic switching vectors and sectors Figure : Three-Phase oltage source Inverter For each sector we can deterine the ON/OFF tie period of each switch and this switching tie in any sector is calculated by using equations (3) & (4) [7]. olue 4 Issue 7, July 05 Paper ID: SUB Licensed Under Creative Coons Attribution CC BY

3 T 3T sref n T sin( 3 International Journal of Science and Research (IJSR) ISSN (Online): Index Copernicus alue (03): 6.4 Ipact Factor (03): ) 3T s ref ( n ) sin( ) 3 T T T s T (3) (4) 0 (5) Here T s is tie period of the switching sequence. By using these switching tie periods, we can generate the switching tie of each switch in any sector and the switching tie of the switches are shown in table-[0]. Table: Switching tie table at each sector sector Upper switches (S, S 3, S 5 ) Lower switches (S 4, S 6, S ) S =T +T +T 0 / S 3 =T +T 0 / S 5 =T 0 / S 4 =T 0 / S 6 =T +T 0 / S =T +T +T 0 / S =T +T 0 / S 3 =T +T +T 0 / S 5 =T 0 / 3 S =T 0 / S 3 =T +T +T 0 / S 5 =T +T 0 / 4 S =T 0 / S 3 =T +T 0 / S 5 =T +T +T 0 / 5 S =T +T 0 / S 3 =T 0 / S 5 =T +T +T 0 / 6 S =T +T +T 0/ S 3 =T 0 / S 5 =T +T 0 / S 4 =T +T 0 / S 6 =T 0 / S =T +T +T 0 / S 4 =T +T +T 0 / S 6 =T 0 / S =T +T 0 / S 4 =T +T +T 0 / S 6 =T +T 0 / S =T 0 / S 4 =T +T 0 / S 6 =T +T +T 0 / S =T 0 / S 4 =T 0 / S 6 =T +T +T 0 / S =T +T 0 / 3. Discontinuous Space ector Pulse Width Modulation (DSPWM) To obtain SPWM, we require two non zero voltage vectors and two zero vectors in each sector and one zero vector (000) start at the start of the switching period, another zero vector () end at the switching period[4]. It is possible to join the two successive half cycle non-zero voltage vectors, to eliinate one zero voltage vector resulting in discontinuous space vector PWM (DSPWM). Because of this ethod, switching period of the sector is reduced, as a result switching losses are reduced [3]. There are two types of odulation schees are available in DSPWM depending on the variation in the placeent of the zero vectors Discontinuous odulation a) DPWMMIN b) DPWMMAX Discontinuous odulation a) DPWM0 b) DPWM c) DPWM In 0 0 Discontinuous odulation, fix the lower bus as selected 0 (000) for all six sectors is called DPWMMIN and fix the upper bus as selected 7 () for all six sectors is called DPWMMAX. olue 4 Issue 7, July 05 In 60 0 Discontinuous odulation, alternatively place zero vectors for successive 60 0 segents. In this, DPWM is fixed at positive and negative bus for each sector which is suitable for resistive load. In DPWM0 and DPWM, alternatively place zero vectors in each 60 0 variation depend up on the peak value of the load current at each Both types give higher reduction in switching losses than DPWM.all aong these ethods DPWM is the ost preferable ethod for power factor correction operation [6]. Figure 4: 60 0 Discontinuous odulation In DPWM (30 0 lagging ode), to illustrate the odulation ethod, take S a, S b, Sc are the control signals for top switches for three phase inverter. If we consider reference vector as sector, phase A voltage becoe the axiu voltage copare to other the phases. Therefore the top switches of the phase A will keep in conduction in sector [9]. According to this, the peak value of the phase A is positive at sector and negative at sector4. On the other hand the peak value of the phase B is positive at sector3, negative at sector6 and the peak value of the phase C is positive at sector5, negative at sector[6]. 4. Coparative analysis We can show the iproveent in the perforance of singlephase to three phase syste using DSPWM copare to SPWM by showing the iproveent in total haronic distortion (THD), coon ode voltage (CM), switching losses, power factor correction (PFC). 4. Total Haronic Distortion (THD) THD of a signal is easureent of the haronic distortion present in that signal and this is defined by the ratio of the su of the power of all haronic coponents to the power of the fundaental frequency. THD is used for describe the power quality of electric power syste. Consider a syste with an ac source and electric load (load is going to take to one of the two loads linear or non linear). If Paper ID: SUB Licensed Under Creative Coons Attribution CC BY

4 ISSN (Online): Index Copernicus alue (03): 6.4 Ipact Factor (03): we consider linear loads, we can get sinusoidal current or voltage wave for, otherwise the current wave for deviates fro a sinusoidal, because of this deviates distortion are created in that wave for, it is coposite of ultiple wave fors called haronics [7]. Frequencies of haronics are integral ultiple of the fundaental frequency. Given 50HZ fundaental wave for, the nd, 3 rd, 4th haronic coponents will be at 00HZ, 50HZ and 00HZ respectively. THD can be calculated by using equation (6) n THD *00% (6) Where, 3, 4 are the haronic coponents of voltage wave for and is the fundaental coponent of voltage wave for. In power syste, lower THD eans reduction in peak currents, heating, eissions and core loss in otors. iportant paraeter for analyzing the syste efficiency, i.e. if we reduce the switching losses in the syste, the point of load syste efficiency increases. So, for the designers of converters accurate switching loss odel becoe the iportant target. To iprove reliability of the design based on the calculation of the junction teperature tie behavior, it is necessary to calculate the switching losses[9]. The switching losses in the IGBT and the Diode are the product of switching energies & the switching frequency (f sw ). P ( E E ) f (9) P swt swd ont offt E E ) f sw ( (0) ond offd Here the turn- on energy losses in IGBT (E ont ) can be calculated as the su of the switch on energy without taking reverse recovery process in to account(e onti ) and the switch on energy caused by the reverse recovery of the freewheeling diode(e ontrr ) and turn-on energy in the diode consists ostly of the reverse-recovery energy(e ond ). E E E () ont onti ontrr sw 4. Coon Mode oltage (CM) The coon ode voltage is defined as the difference between stator neutral point of the otor and electrical ground or bus id-point. By considering switching function of the inverter S x using SPWM and bus voltage, we can get the voltage at the neutral point of the otor. Then, the neutral point voltage is defined as xg ( Sx ) (7) When S x =, the upper switch of the corresponding phase Ar of the inverter is turned-on S x =0, the lower switch of the corresponding phase Ar of the inverter is turned-on Then Coon ode voltage (CM) here is defined as neutral voltage with respective to the bus id-point. So co 3 c xa S x Equation (8) shows that the CM will have the agnitude of or depending up on the switching frequency. 6 Since the coon ode voltage (CM) changes aong the above switching pattern of the inverter, it induces otor shaft voltages and bearing currents that can result in preature otor bearing failures. Also, the coon-ode voltage can cause coon-ode current to flow through the ground conductor of the otor and back into the power ains causing conducted EMI[8]. (8) 4.4 Power Factor Correction Power factor is the ratio between the useful power (KW) to the total power (KA) consued by an ite of a.c electrical equipent. The ideal power factor is unity. If the power factor of the equipent is less than one, extra power is required to get the unity value [0]. Basically the poor power factor is caused by the significant phase difference between the voltage and current at the load terinal or due to the high haronic content or distorted current wavefor. 5. Siulation Results The siulation output voltages of the single phase to three phase syste using SPWM and DSPWM control techniques are shown in Fig.5&6. The Total Haronic Distortion (THD) of SPWM&DSPWM is shown in Fig.7&8 respectively. Fro that graphs we can observe that the THD of the DSPWM is less copare to SPWM. Because of the reduction in the THD, the power factor iproves. The Coon-ode oltage (CM) of SPWM&DSPWM is shown in Fig.9&0 respectively. Fro that graphs we can observe that the positive voltage of DSPWM is less copare to SPWM. So DSPWM iproves the Coon-ode oltage. In SPWM technique four switches are conduction in each sector and only three switches are conduction in DSPWM technique. So the switching losses are less in this syste using DSPWM technique copare to SPWM technique. 4.3 Switching Losses In power electronics switching losses typically contribute a significant aount to the total syste losses and it is the olue 4 Issue 7, July 05 Paper ID: SUB Licensed Under Creative Coons Attribution CC BY

5 ISSN (Online): Index Copernicus alue (03): 6.4 Ipact Factor (03): (a) (b) Figure 6: DSPWM Output oltages a) Line oltage b) Phase oltage (b) Figure 5: SPWM Output oltages a) Line oltage b) Phase oltage Figure7: Total Haronic Distortion (THD) of SPWM Figure 8: Total Haronic Distortion (THD) of DSPWM (a) olue 4 Issue 7, July 05 Paper ID: SUB Licensed Under Creative Coons Attribution CC BY

6 ISSN (Online): Index Copernicus alue (03): 6.4 Ipact Factor (03): Figure 9: Coon Mode oltage (CM) SPWM Figure 0: Coon Mode oltage (CM) DSPWM 6. Conclusion By the parallel connection of two rectifiers at the input side, we can reduce the haronic distortion, rectifier switch currents and iproves the fault tolerance characteristics. Fro the results we can observe that the iproveent in the Total haronic distortion (THD), Power factor, Coonode oltage (CM) and switching losses of the syste by using DSPWM technique copared to SPWM technique. References [] Cursino Brandao Jacobina, Euzeli Cipriano dos Santos, Nady Rocha and Edgard Luiz Lopes Fabr ıcio Single- Phase to Three-Phase Drive Syste Using Two Parallel Single-Phase Rectifiers IEEE Transactions on Power Electronics, vol. 5, no. 5, pp.85-95, May 00. [] Euzeli Cipriano dos Santos, Cursino Brandao Jacobina, Jose Artur Alves Dias, and Nady Rocha Single-Phase to Three-Phase Universal Active Power Filter IEEE Transactions on Powe Delivery, vol. 6, no.3, pp.36-37, July 0. [3] Euzeli Cipriano dos Santos, Cursino Brand ao Jacobina, Edison Roberto Cabral da Silva, and Nady Rocha Single-Phase to Three-Phase Power Converters: State of the Art IEEE Transactions on Power Electronics, vol. 7, no. 5, pp , May 0. [4] Euzeli Cipriano dos Santos, Cursino Brandão Jacobina, Gregory Arthur de Aleida Carlos, and Isaac Soares de Freitas Coponent Miniized AC DC AC Single- Phase to Three-Phase Four-Wire Converters IEEE Transactions on Industrial Electronics, vol. 58, no. 0, pp , October 0. [5] Kazuya Inazua, Hiroaki Utsugi, Kiyoshi Ohishi, and Hitoshi Haga High-Power-Factor Single-Phase Diode Rectifier Driven by Repetitively Controlled IPM Motor IEEE Transaction on Industrial Electronics, vol. 60, no. 0, pp , October 03. [6] Euzeli Cipriano dos Santos, Nady Rocha, and Cursino Brandao Jacobina Suitable Single-Phase to Three- Phase AC DC AC Power Conversion Syste IEEE Transaction on Power Electronics, vol.30, no., pp , Feb 05. [7] K. inoth Kuar, Prawin Angel Michael, Joseph P. John and Dr. S.Suresh Kuar Siulation and coparison of SPWM and SPWM control for Three- Phase Inverter ARPN Journal of Engineering and Applied Sciences, vol.5, no. 7, pp. 6-74, July 00. [8] Said Ahed-Zaid, Elisa Barney Sith, and John Chiasson MATLAB/Siulink Ipleentation and Analysis of Three Pulse Width-Modulation (PWM) Techniques Master of Science in Electrical Engineering, May 0. [9] Ahet M.Hava, and N. Onur Cetin A Generalized Scalar PWM Approach With Easy Ipleentation Features for Three-Phase,Three-Wire oltage-source Inverters IEEE Transactions on Power Electronics, vol. 6, no. 5, pp , May 0. [0] M. Kubeitari, A. Alhusayn, and M. Alnahar Space ector PWM Siulation for Three Phase DC/AC Inverter World Acadey of nscience, Engineering and Technology, vol. 6, pp , Dec 0. [] Atif Iqbal, Adou Laine, Itiaz Ashraf, and Mohibullah Matlab/Siulink odel of Space ector olue 4 Issue 7, July 05 PWM for Three-phase voltage source Inverter. [] Mahaad Arif Khan, Atif Iqbal, and Abu Rub Haitha Investigation of Discontinuous Space ector PWM Techniques of a Three-Phase voltage source Inverter i-anagers journal on Electrical Engineering, vol.,no. 3, pp. 60-7, Jan-March 009. [3] Atif Iqball, Sk Moin Ahed, Mohaad Arif Khan, and Haitha Abu-Rub Generalised siulation and experiental ipleentation of space vector PWM technique of a three-phase voltage source inverter International Journal of Engineering, Science and Technology, vol., no., pp.-, 00. [4] Atif Iqbal, Mohd. Arif Khan, Sk. Moin Ahed, M. Rizwan Khan, and Haitha Abu-Rub Analysis of Discontinuous Space ector PWM Techniques for a Five-phase oltage Source Inverter International Journal of Recent Trends in Engineering, vol., no. 5, pp.-6, Nov 009. [5] Mahaad H.Rashid Power Electronics Circuits, Devices, and Applications Prentice Hall,. [6] Chakrapong Charuit and ijit Kinnares Discontinuous SPWM Techniques of Three-Leg SI-Fed Balanced Two-Phase Loads for Paper ID: SUB Licensed Under Creative Coons Attribution CC BY

7 ISSN (Online): Index Copernicus alue (03): 6.4 Ipact Factor (03): Reduced Switching Losses and Current Ripple IEEE Transaction on Power Electronics, vol. 30, no. 4, pp , April 05. [7] Lundquist and Johan On Haronic Distortion in Power Systes, Chalers University of Technology: Departent of Electrical Power Engineering, 00. [8] Mohan M. Renge and Hiralal M. Suryawanshi Five- Level Diode Claped Inverter to Eliinate Coon Mode oltage and Reduce dv/dt in Mediu oltage Rating Induction Motor Drives IEEE Transactions on Power Electronics, vol. 3, no. 4, pp , July 008. [9] Dr.Dusan Graovac, Marco Purschel IGBT Power Losses Calculation Using the Data-Sheet Paraeters Application Note,., Jan 009. [0] John Ware Power Factor Correction. olue 4 Issue 7, July 05 Paper ID: SUB Licensed Under Creative Coons Attribution CC BY