a new structure for three-phase to single-phase ac-ac matrix converters

8/14/2019 A New Structure for Three-phase to Single-phase Ac-Ac Matrix Converters

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As we know this matrix converter consists of 3x1 switches.The 3 x 1 switches give 8 combinations of switching states,which are decreased to only 3, permitted states, if the two basicrules to operate this converter safely are appliedFor preventing of short-circuit of power supplies, donot connect two different input lines to the sameoutput line (over currents);For preventing of open circuit of the load (inductive),do not disconnect the output line circuits (overvoltages),Table 1 shows the matrix converter electric modes. As theTable 1shows he patterns of switches are in such a way thatthey cause the input voltages do not short-circuit and also theoutput current do not open-circuit. We emphasis that the peakvalue of the output voltage for this circuit is equal to the peakvalue of the input voltages. In this case, the input currents havediscontinuous waveforms but there is continuous current at theoutput terminals

Table 1. The electric modes, output voltage and currentequations connections for the first form of the matrix converter

Modes

first case but there is continuous current at the output terminalsPI.

ON Switches v o I io I

3. THE PROPOSED STRUCTURE FOR THREE-PHASETO SINGLE-PHASEAC/AC MATRIX CONVERTERThe novel form of the three-phase to single-phase ACIACmatrix converter is shown schematically in Fig. 4.It consists ofsix bi-directional switches SI1, lz , Szl, SZ2,S3L and S32 similarthe second form with two extra SN and Sp switches.

The second form of the three-phase to single-phase ACIACmatrix converter is shown schematically in Fig. 3.It consists ofsix bi-directional switches S I 1 , l2, S z l , S22, s31 and s 3 2 .As we know this matrix converter consists of 3x2 switches.The 3 x 2 switches give 64 combinations of switching states,which are decreased to only 6 permitted states, if the two basicrules that previously mentioned for safe operating of thisconverter are applied. Of course there is also a seventh mode.Mode 7 is occurred when ( & I , SIZ) r (SZI, 22 ) or ( s 3 1 , s 3 2 ) areclosed. At this mode the output voltage and also the inputcurrents will be zero. Since we want to have continuouscurrents as possible as the input sides and also V , = 0 may beoccurred in the other modes that specified at Table 2, weneglect the mode 7.

Figure3. The second form of the three-phase to single-phaseACIAC matrix converter

1s3 2

I S P + v * -U-Figure4.The novel structure of the three-phase to single-phaseACIAC matrix converter

Table 2 shows the matrix converter electric modes. As theTable 2 shows, in this case we have 6 modes, and at everymode the output voltage always consist of the differencebetween two voltages at the input sides. Therefore, the peakvalue of the output voltages for the circuit shown in Fig. 3 isBy use of six bi-directional switches we will have lessdiscontinuous currents at the input terminals with respects to the

equal AV , .

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The mechanism control of these converters is based on theminimum difference between the measured and the forecastedoutput. In this new converter we have 12 Modes, 12 states ofdifferences (Errors) between the measured and the forecastedoutp~t s, El, &, E3, E4, E5,Es. E7, Es. Eg, EIO,Ell, E12). Inanother words we have:IF(min( E , , E , , ... , E n ) = E , )THEN S,, ON A ND S,, = ON

THEN S,, = ON AND S,, = ONTHEN S,, = ON AND S,, = ONTHEN S,, = ON AND S,, = O NTHEN S,, = ON A ND S,, = ONTHEN S,, = ON AND S,, = ONTHEN S,, = ON A ND S, = ONTHEN S,, = ON AND S, = ONTHEN S, , = ON AND S , = ONTHEN S , , = O N AND S, = O NTHEN S , , = ON AND S, = ONTHEN S,, = ON A ND S, = ON

IF(min( E , , E , , ... , E , , ) = E , )IF(min( E , , E , , ... , E , , ) = E , )I F (m i n ( E , , E , , ... , E , , ) = E d )IF (min( E , , E , , ... , E , , ) = E , )IF (mi n( E i , E 2 , ... , E l , ) =IF(min( E , , E , , ... , E l 2 )= E 7 )IF(min( E , , E , , ... , E , , ) = E * )IF(&( E 1 7 E 2 , ... , E n ) = E , )IF(min( E , , E , , ... , E , , ) = E l o )IF (min( E , , E , , ... , E , , ) = E , , )IF(min( E , , E , , ... , E , , ) = E , , )

The relation between the output voltage and current for the load( R- ) for circuits shown in Figs. 2, 3 and 4 is given by:

d io (4v , ( t ) = R i , ( t ) + L - dt (3 )and the fundamental of the output voltage is given by equation(2). From Eqns. (2) and (3), the fundamental of the outputcurrent is given by:

4. SIMULATION RESULTSWe use the Simulink Matlab and PSpic softwares. The resultsshow that we can obtain the expecting results. According to theoperation principle, the input and output currents and voltageswaveforms may be determined by the digital simulationmethod. Ideal switches constitute the matrix converters. For

indicating the ability of this new matrix converter forcontinuous changing of both amplitude and frequency, we givethe waveforms of the different output vollages, when theparameters of input voltage are IT, = 2 2 0 Y , j = 50"' (Figs. 5and 6 ) . v , - 2-v. P I -w e . F"* - 1oowr.m

Figure 5. The waveforms of h e output voltages andfundamental at di fferent output amplitude for circuit shown inFig. 4 under undistorted condition:; when the forecasted outputfrequency is f, = IOOHZ

Figure 6. The waveforms of the $output oltages at differentoutput ftequency and them fundamental for E ircuit shown inFig.4 under undistorted conditions when the forecastedamplitude of output voltage is V , = 250 'Since the number of states for this new matrix converter ismore than those for the other clarsical matrix converters, theoutput voltage of this new converter has the fundamental andvery small high order harmonics. Also the range of thecontinuous control of the amplitude of output voltage by thisnew matrix converter is very larger that for the other classicalmatrix converters (about from 031:: to fir', ), and there is no

limitation in changing of the outpul frequency. Therefore can beproduced any favorable output with variable kequency andamplitude. In order to indicate the ability of this novel matrixconverter, we will compare the ouqput voltage waveforms of thetwo converters shown in Figs. 3 and 4 at different amplitudes.We emphasis that both of circuits have no limitation inchanging of the output frequency(Figs. 7and 8).

0.01 Tin,elSecl O . O Z * ~ ~ , , 0.01 r imelsecl 0.02zo o

Figure7. The output voltages at different amplitudes; he leftcolumn for the circuit shown in Fig. 3, and the right column forthe circuit shown in Fig. 4

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Figure 8. The output voltages at different amplitudes; the leftcolumn for the circuit shown in Fig. 3 and the right column forthe circuit shown in Fig. 4One of the important and the valuable characteristic of thisnovel matrix converter is that even under unbalanced andhighly distorted input voltage waveforms, the output waveforms

turn out to be reasonably clean and balanced and this ability isshown in simulation results. If we suppose that the inputvoltages are unbalanced and significantly distorted, for exampleexpressed as follows [4], [SI:

5a4vil(t) = 1.3Vi sin(wit--)+0.25Vi sin(2wit)

vi2(t)= Vi sin(wjt+)+0.15V, sin(3wit)3vi3(t)= 1.2Vi sin(w,t--)+0.2Vj sin(50it ) ( 5 )2

Then simulation results show that the output waveformsturn out to be reasonably clean and balanced and this ability isshown Figs. 9 and 10.

Figure 9. The waveforms of the output voltages for the circuitshown in Fig. 4at the different output ampli tudes underdistorted and unbalanced conditions.

Figure 10. The waveforms of the output voltages for the circuitshown in Fig. 4at the different output frequency under distortedand unbalanced conditions.Let us summarize some results of this research:0 Since the number of states for this new matrix converter is

more than those for the other classical matrix converters,the output voltage of this new converter has thefundamental and very small high order harmonics.The peak value of the output voltages for the circuitshown in Fig. 2 is equal with the peak value of the inputvoltages, and for circuits shown in Figs. 3 and 4 is equalBy this novel method every one can produce anyfavorable output with the variable frequency andamplitude.The output voltages contain fundamental and someadditional high order harmonics.The output currents contain high order harmonics.Since the load of the converters is almost a low pass filter(R-L), then the output currents contain less high orderharmonics than the output voltages.Because of the less number of switching, this novelmethod gives very low loss converters.One of the important and valuable characteristic of thisnovel matrix converter is that even under unbalanced andhighly distorted input voltage waveforms, the outputwaveforms turn out to be reasonably clean and balanced

& V i .

5. CONCLUSIONSThis paper has presented a new structure for three-phase tosingle-phase AC/AC matrix converters. By this new structure,any favorable output with variable frequency and amplitude canbe produced. This new matrix converter is step-up and step-down for both frequency and amplitude. In other words, thisconverter is capable of converting any input waveform with anygiven angular frequency, to any output waveform with anyangular frequency from zero @C output) to very highfrequencies with favorable output amplitude. Using this novelcontrol method, ensures that the switches do not short-circuitthe voltage sources, and do not open-circuit the current sources.Also for the less number of switching, these converters are verylow loss converters. The most important and valuablecharacteristic of this converter is that even under unbalancedand significantly distorted input voltage waveforms, the outputwaveformsturn out to be reasonably clean and balanced.

6. REFERENCESS. Sunter, and J. C. Clare, A true Four Quadrant MatrixConverter Induction Motor Drive with ServoPerformance, PESC96, Baveno, June 23-27, 1996, pp.S.H. Hosseini, and E. Babaei, A New GeneralizedDirect Matrix Converter, ISIE2001, Pusan, Korea, JuneS.H. Hosseini, and E. Babaei, A Novel ModulationMethod for DC/AC Matrix Converters under DistortedDC supply Voltage, IEEE TENCONO2, Beijing, China,October 28-31,2002, vol. III, pp. 1970-1973.S.H. Hosseini, and E. Babaei, A New Control Algorithmfor Matrix Converters under Distorted and UnbalancedConditions, Proceding of 2003 IEEE Conference onControl application (CCAU3), Istanbul, Turkey, June 23-S . Khanmohammadi, A. Aghagolzadeh, S.H. Hosseini,and E. Babaei, A New Algorithm for Three-phase toSingle-phase ACIAC Matrix Converters, Accepted andwill be present in I dh EEE International Conference onElectronics, Circuits and Systems (ICECS 2003). Sharjah,United Arab Emirates (U.A.E.), December 14-17,2003.

146-1 1.

12-16,2001, vol. 2, pp. 1071-1076.

25,2003, vol. 2, pp. 1088-1093.

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a new structure for three-phase to single-phase ac-ac matrix converters

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