Investigation of Switching Loss Reduction for the Matrix Converter Based on Virtual AC/DC/AC Conversion using Space Vector Modulation

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1 Inetigation of Switching Lo Reuction for the Matrix Conerter Bae on Virtual AC/DC/AC Conerion uing Space Vector Moulation Jun-ichi Itoh Dept. of Electrical, Electronic an Information Engineering Nagaoka Unierity of Technology Nagaoka, Niigata, Japan Takumi Mura Dept. of Electrical, Electronic an Information Engineering Nagaoka Unierity of Technology Nagaoka, Niigata, Japan Hiroki Takahahi Dept. of Electrical, Electronic an Information Engineering Nagaoka Unierity of Technology Nagaoka, Niigata, Japan Abtract Thi paper propoe a pace ector moulation bae on the irtual AC/DC/AC conerion metho for a matrix conerter to reuce the witching lo. The witching lo of the matrix conerter i not ecie by only the number of witching time but alo epening on the oltage an current in the electe witching eice bae on the moulation. The propoe metho can minimize the maximum intantaneou witching lo which i caue by the election of witching tate with the abolute maximum alue in the input oltage an the output current. Thi can be achiee by changing oer the zero-ector of irtual inerter in the propoe metho. In thi paper, the lo characteritic of the matrix conerter uing the propoe metho are emontrate experimentally. From the experimental reult, it wa confirme that the propoe metho can reuce the loe by 23.9 % in comparion with a conentional pace ector moulation metho. Keywor-matrix conerter; witching lo; irtual AC/DC/AC conerion; pace ector moulation; I. INTRODUCTION Recently, the matrix conerter which can conert an AC power upply oltage into an AC output oltage that elier ariable amplitue an frequency without the large energy torage, uch a electrolytic capacitor, hae been actiely tuie [1-11]. Matrix conerter hae aantage uch a light-weight an long life-time ue to no large paie component in the main circuit. In aition, matrix conerter can achiee high efficiency becaue of le witching eice in the current path, in comparion with a Back-to-Back ytem, which conit of a PWM rectifier an a PWM inerter. Therefore, many control metho for matrix conerter hae been propoe an hown the following benefit, low witching lo, low input current harmonic, an low output oltage harmonic [6-11]. In orer to reuce the harmonic component an witching lo, many PWM trategie of matrix conerter hae been tuie [8-11]. Almot of the conentional metho ecreae the witching time of matrix conerter, which aim at reucing the witching lo, imilar to the other conerter ytem. Howeer, the witching lo of the matrix conerter i not etermine by only the number of the witching time becaue the oltage an current of the witching eice are ariable at any time. Moreoer, the oltage an current of the eice are electe among the three-phae input oltage an output current. Thu, the intantaneou witching lo of a eice occur with nine combination of the input oltage an the output current. From thee reaon, if the number of witching time i reuce, the total witching lo may not be ecreae becaue large turn-on or turn-off lo occur per witching. In other wor, if the turn-on or turn-off lo per witching can be maller, the total witching lo can be reuce in pite of the number of witching time. Thi paper propoe a pace ector moulation (SVM) control metho to reuce the witching lo of matrix conerter bae on the irtual AC/DC/AC conerion metho. The propoe metho can minimize the maximum intantaneou witching lo which i generate at the eice yntheizing the input oltage an the output current with the intantaneou abolute maximum alue. The propoe metho change oer the zero-ector of the irtual inerter to aoi the witching of the eice which connect between the input phae with the intantaneou abolute maximum oltage an the output phae with the intantaneou abolute maximum current. That i, the witching tate yntheize by the propoe metho o not hae intantaneou maximum witching lo. At firt, thi paper ecribe the SVM bae on the irtual AC/DC/AC conerion. Secon, the principle of the witching lo reuction by the propoe metho i preente. Finally, the experiment uing a 2-kW prototype i emontrate to confirm the aliity of the propoe metho in term of lo characteritic. A thee reult, it i confirme that the propoe SVM metho can reuce the witching lo in the entire loa power. II. VIRTUAL AC/DC/AC CONVERSION METHOD Fig. 1 how the circuit configuration of the matrix conerter. Matrix conerter conit of a LC filter an nine biirectional witche. The irtual AC/DC/AC control metho wa propoe a a control technique for the matrix

2 conerter [4]. Then, the output phae oltage t [ u w ] are hown a (1) uing input phae oltage t [ r t ]. u w ru r rw u w tu t tw r t where nm i uty ratio of the witch in the matrix conerter (n: input phae, m: output phae) which i etermine form to 1. Fig. 2 how the irtual AC/DC/AC conerion ytem which i contructe by a rectifier an an inerter. The irtual AC/DC/AC control metho conier the matrix conerter a a irtual rectifier an a irtual inerter to obtain eignate witching pule comman. The rectifier i controlle a a current ource type rectifier, an the inerter i controlle a a oltage ource type inerter. The witching tate in Fig. 1 can be expree by the witching tate in Fig. 2. Equation (2) expree the formula for the uty compoition in a matrix conerter. Figure 1. Circuit configuration of the matrix conerter. ru r rw u w tu t tw up p wp un n wn rp rn p n tp tn where, ij i uty of the witch in the irtual AC/DC/AC conerter (i: r,, t, u,, w, j: p, n). Accoring to (2), the uty comman of the irtual rectifier an the irtual inerter are multiplie by each upper arm (p ie) an lower arm (n ie), repectiely. Then, the uty comman of the matrix conerter are obtaine from the multiplie uty comman. A. Determination of the irtual rectifier ector Fig. 3 how the pace ector iagram of the irtual rectifier. I 1 ~ I 6 are the input phae current ector. Inex of the input current ector repreent the witching tate of the irtual rectifier witche. For example, (RT) inicate that S rp an S tn are in ON tate an other witche are in OFF tate in Fig. 2. It i aume that the comman ector of the irtual rectifier i in ector 1 in Fig. 3. Then, -axi an -axi component of the input current comman ector I in are expree by -axi an -axi component of the input phae current ector I 1 an I 2, an it utie are obtaine by (3). I I I1 I1 1 in I 2 in1 in I 2 in2 1 1 in 1 where, ink i uty ratio of the input phae current ector in the electe ector (k: ~ 6). Figure 2. Virtual AC/DC/AC conerter which generate ame input an output waeform with the matrix conerter in Figure 1. Figure 3. Space ector iagram of the irtual rectifier. B. Determination of the irtual inerter ector Fig. 4 how the pace ector iagram of the irtual inerter. V 1 ~ V 6 are the output phae oltage ector. Inex of the output oltage ector are the witching tate for the irtual inerter witche. For example, (11) inicate that S up, S p an S wn are in ON tate an other witche are in OFF tate in Fig. 2. It i aume that the comman ector of the irtual inerter i in ector 1 of Fig. 4. Then, -axi an -axi component of the output oltage comman ector V out are expree by -axi an -axi component of the output phae oltage ector V 1 an V 2, an it utie are obtaine by (4).

3 V V V1 V1 1 out V2 out1 out V2 out out 1 where, outl i uty ratio of the output phae oltage ector in the electe ector (l: ~ 6). C. Compoition of the witching tate The witching tate of the matrix conerter bae on the irtual AC/DC/AC conerion metho epen on the witching tate of the irtual rectifier an inerter. Therefore, if the irtual inerter output zero-ector which mean that the output oltage i zero, the matrix conerter can output three zero-ector ue to the witching tate of the irtual rectifier. Table I how the witching tate of the matrix conerter focue on the zero-ector of the irtual inerter. Then, for example, (RRR) of the matrix conerter ector inicate that all output phae connect to input R-phae. The inerter ha two zero-ector which are expree by () an (111). A hown in Table I, the matrix conerter output one of three zero-ector when the inerter output zero-ector. Therefore, the matrix conerter bae on the irtual conerion metho ha reunancy to the zero-ector. Any zero-ector in the irtual inerter can be electe becaue the zero-ector oe not affect the input an output waeform. A hown Table II, when witching tate change from (TRT) to (TTT), -phae i connecte from R-phae to T- phae only. On the other han, when witching tate change from (TRT) to (RRR), u-phae an w-phae are in witching. Therefore, witching tate are ifference ue to electe inerter zero-ector. In aition, it i confirme that the intantaneou witching lo epen on not only the witching time but alo the relationhip between the input an output phae ue to the electe reunant zero-ector of the irtual inerter [11]. III. REDUCTION FOR SWITCHING LOSS BY ZERO- VECTORS It i aume that the comman ector of the irtual rectifier i in ector 1 in Fig. 3 an the comman ector of the irtual inerter i in ector 1 in Fig. 4. Then, the comman ector of the irtual rectifier i yntheize by the input phae current ector, (RS), (RT) an (RR). Then, it i confirme that S rp in the irtual rectifier i in on-tate uring ector 1. In other wor, the maximum phae in the input oltage i r-phae uring ector 1 in orer to get the larget oltage at the irtual DC-link part in Fig. 2. Thu, the maximum input oltage phae i itinguihe from other two input phae by on-tate witch uring it ector. Fig. 5 how the eciion metho of the abolute maximum oltage phae uing the mile phae pole in the irtual inerter. Thi i a metho to itinguih the output phae with the abolute maximum current alue without enor. Note that thi metho can be ue when the output power factor i almot unity only. The output phae with the Figure 4. Space ector iagram of the irtual inerter. TABLE I. SWITCHING STATES OF THE MATRIX CONVERTER FOCUSED ON THE ZERO-VECTORS OF THE VIRTUAL INVERTER. Rectifier ector Inerter ector Matrix conerter ector RS RT TABLE II. SSS TTT THE DIFFERENCE OF SWITCHING PHASE DUE TO THE REDUNDANCY OF ZERO-VECTOR Before TRT TRT (a) V mi <. (b) V mi >. After TTT RRR Figure 5. Deciion metho of the abolute maximum oltage phae uing mile phae uing the mile phae pole in the irtual inerter.

4 abolute maximum phae oltage comman change accoring to pole of the mile phae oltage comman (V mi ) in Fig. 5. At ector 1 in Fig. 5, when the pole of the mile phae oltage comman i negatie, it can be confirme that the maximum oltage comman phae i u- phae. On the other han, when the pole of the mile phae oltage comman i poitie, the maximum oltage comman phae i w-phae. When the output power factor i almot unity, the output current phae correpon to the output oltage comman. Hence, the maximum output current phae i itinguihe from other two output phae by the metho in Fig. 5. Table III how the compoition of the witching tate for the matrix conerter in ector 1 of the pace ector iagram of the irtual rectifier an in ector 1 of the pace ector iagram of the irtual inerter. A mentione aboe, in thee ector, the input phae with the intantaneou abolute maximum oltage i r-phae an the output phae with the intantaneou abolute maximum current i u-phae uring V mi < or w-phae uring V mi >. Accoring to Table 3, in region of V mi <, u-phae i connecte to r- phae in on-tate at any time when the zero-ector of the irtual inerter i (111). Therefore, the maximum intantaneou witching lo i not generate becaue S ru in Fig. 1 i not in witching operation. If the zero-ector () i electe in thi region, S ru i in witching operation an the maximum intantaneou witching lo occur. On the other han, in region of V mi >, w-phae i connecte to r-phae with the leat witching time when the zero-ector of the irtual inerter i (). Thu, the maximum intantaneou witching lo i minimize becaue S rw in Fig. 1 i in witching operation with the leat witching time. If the zero-ector (111) i electe in thi region, the witching time of S rw will increae an the maximum intantaneou witching lo i generate more. Fig. 6 how flowchart for the propoe metho to generate the utie for matrix conerter. Input comman ector I in i obtaine by tranforming input 3-phae current comman i r, i, i t to -frame. Next, the input ector i checke by the input current comman ector. Then, the irtual rectifier utie can be calculate by (3) an itribute to the witche compoing the input phae current ector in the electe ector. The irtual inerter utie are alo calculate by (4) uing the output 3-phae oltage comman. Each ector uty i tranforme to the utie of the inerter witche by (5) an (6). TABLE III. COMPOSITION OF THE SWITCHING STATES FOR MATRIX CONVERTER IN SECTOR 1 OF THE SPACE VECTOR DIAGRAM OF THE VIRTUAL RECTIFIER AND IN SECTOR 1 OF THE SPACE VECTOR DIAGRAM OF THE VIRTUAL INVERTER. V mi < V mi > Virtual rectifier RS RT RR RS RT RR Virtual inerter Matrix conerter 11 RRS 1 RSS 11 RRT 1 RTT 11 RRR 1 RRR 11 RRS 1 RSS SSS 11 RRT 1 RTT TTT 11 RRR 1 RRR RRR up p wp up1 p1 wp1 up 2 p 2 wp 2 up p wp out1 out 2 out un n wn 1 1 p 1 up wp Figure 6. Flowchart to generating uty for matrix conerter.

5 TABLE IV. EXPERIMENTAL PARAMETERS. Input oltage (line-to-line) 2V Input frequency 5Hz Output frequency 45Hz Moulation inex of MC.9 Loa R-L (16W) Carrier frequency 1kHz LC filter f c 98Hz Input phae oltage r 25[V/i] Input current i r 1[A/i] Output line oltage u 25[V/i] Output current i u 1[A/i] Time 1[m/i] (a) The conertional SVM metho. Loa (b) The propoe SVM metho. Figure 7. Control block iagram of the propoe SVM metho. The block of zero-ector change oer i ae to the control block iagram of the conentional SVM metho where, xyz i witching function. Then, xyz = 1 correpon to on-tate an xyz = correpon to off-tate (x: u,, w, y: p, n, z: ~6). At the block of zero-ector change oer in the flowchart, the inerter zero-ector i change by pole of the mile output oltage, a hown (7). up up 1,, p p 1,, wp wp 1 mi mi IV. EXPERIMENTAL RESULTS Table IV how the experimental parameter. In aition, a conentional SVM that oe not change oer the irtual inerter zero-ector wa experimente, too. Fig. 7 how the control block iagram of the propoe SVM metho. The propoe metho a the Zero-ector change oer block to the conentional control block iagram. Fig. 8 (a) an (b) how the experimental waeform of the conentional SVM an propoe SVM repectiely.. The input current an output current i controlle a inuoial Figure 8. Input an output waeform in teay tate. The propoe SVM metho can achiee the equal or higher performance in comparion with the conentional SVM metho. waeform an unity input power factor i obtaine in both control metho. The total harmonic itortion (THD) in the input current an output current are 4.8% an 2.1 % in Fig. 8 (a). On the other han, the THD in the input current an output current are 4.4 % an 1.4% in Fig. 8 (b). Thu, the propoe SVM metho can achiee the equal or higher performance in comparion with the conentional SVM metho. Fig. 9 how a lo analyi between the propoe an conentional SVM metho. In Fig. 9, the propoe metho can reuce lo oer the entire loa power region, an the lo by approximately 23.9% can be reuce in comparion with that of the conentional SVM metho at 1.6-kW loa. Then, the efficiency of the propoe SVM metho i 94.1 %. Hence, the propoe SVM can reuce the witching lo of matrix conerter becaue the zero-ector of the irtual inerter are change. Fig. 1 how the witching tate between the conentional an propoe SVM metho when the input ector i 1 an the output ector i 1. The propoe SVM metho oe not elect the zero-ector (TTT) which i electe by conentional SVM metho. Thi i the eience that the propoe SVM metho change two zero-ector an ue only one zero-ector of the irtual inerter to aoi

6 the witching tate to generate the intantaneou maximum witching lo. In aition, the propoe SVM metho reuce witching time by two time becaue the electe zero-ector can be combine at once. In the conentional SVM metho, the zero-ector at the carrier peak an at the carrier bottom are ifferent an are itribute equally, repectiely. Howeer, the propoe SVM metho ue the only ector. Thu, the propoe SVM metho can itribute the zero-ector at the carrier bottom an reuce the witching time. Therefore, the propoe SVM metho coul reuce a lo a compare with conentional SVM metho. V. CONCLUSION Thi paper propoe a pace ector moulation (SVM) control metho in orer to reuce the witching lo of a matrix conerter bae on the irtual AC/DC/AC conerion. The propoe metho focue on the intantaneou maximum witching lo which i generate at the eice yntheizing the input oltage an the output current with the intantaneou abolute maximum alue. In other wor, the propoe metho can reuce the witching lo by the reuction of the witching tate which generate intantaneou maximum witching lo, not the reuction of the witching time. The reuction of the intantaneou maximum witching lo i realize by changing the zeroector of the irtual inerter. From the experimental reult, it i confirme that the propoe metho can control matrix conerter with input an output inuoial waeform. In aition, the propoe metho can reuce lo oer the entire loa power region, an the lo by approximately 23.9% can be reuce in comparion with that of the conentional SVM metho at 1.6-kW loa. Finally, from the tranition of witching tate in 1 carrier perio, it i confirme that the propoe SVM metho oe not elect the zero-ector which generate the intantaneou maximum witching lo. Therefore, the propoe SVM metho i ueful to reuce the witching lo of matrix conerter. Thi tuy wa upporte by Inutrial Technology Grant Program in 29 from New Energy an Inutrial Technology Deelopment Organization (NEDO) of Japan. REFERENCES [1] P. W. Wheeler, J. Roriguez, J. C. Clare an L. Empringham: Matrix Conerter: A Technology Reiew, IEEE Tranaction on Inutry Electronic, Vol. 49, No. 2, pp (22). [2] J. W. Kolar, F. Schafmeiter, S. D. Roun an H. Ertl: Noel Three- Phae AC-AC Spare Matrix Conerter, IEEE Tran. on Power Electronic, Vol.22, No.5, pp , (27) [3] J. Roriguez, M. Riera, J. W. Kolar an P. W. Wheeler: A Reiew of Control an Moulation Metho for Matrix Conerter, IEEE Tran. on Inutrial Electronic, Vol. 59, No. 1, pp.58-7, (212) [4] J. Itoh, I. Sato, A. Oaka, H. Ohguchi, H. Koachi an N. Eguchi: A Noel Approach to Practical Matrix Conerter Motor Drie Sytem With Reere Blocking IGBT, IEEE Tran. on Power Electronic, Vol.2, No.6, pp (25). [5] Y. -D. Yoon, S. K. Sul: Carrier-Bae Moulation Technique for Matrix Conerter, IEEE Tran. on Power Electronic, Vol. 21, No. 6, pp , (26) [6] H. M. Nguyen, Hong-Hee. Lee an Tae-Won. Chun: Input Power Factor Compenation Algorithm Uing a New Direct-SVM Metho for Matrix Conerter, IEEE Tran. on Inutrial Electronic, Vol.58, No.1, pp , (211) Propoe SVM metho Conentional SVM metho Loa Power [kw] Figure 9. Lo characteritic of the propoe an conentional PWM metho. The propoe metho can reuce lo oer the entire loa power region, an the lo by approximately 23.9% can be reuce in comparion with that of the conentional SVM metho at 1.6-kW loa. Figure 1. Switching tate in 1 carrier perio. The conentional SVM metho elect two zero-ector, RRR an TTT. Howeer the propoe SVM metho oe not elect the zero-ector TTT which generate the intantaneou maximum witching lo. [7] C. Klumpner, F. Blaabjerg, I. Bolea an P. Nielen: New Moulation Metho for Matrix Conerter, IEEE Tran. on Inutry Application, Vol. 42, No. 3, pp (26) [8] Y. Taano, S. Hamaa, S. Uruhibata, M. Nomura, Y. Sato an M. Ihia: Direct Space Vector PWM Strategy for Matrix Conerter with Reuce Number of Switching Tranition, IEEJ Tran., Vol.124-D, No.4, pp (28). [9] T. Takehita an Y. Anou: PWM Control of Three-Phae Matrix Conerter for Reucing a Number of Commutation, IEEJ Tran., Vol.127-D, No.8, pp (27). [1] L. Helle, K. B. Laren, A. H. Jorgenen, S. Munk-Nielen an F. Blaabjerg: Ealuation of Moulation Scheme for Three-Phae to Three-Phae Matrix Conerter, IEEE Tran. on Inutrial Electronic, Vol. 51, No. 1, pp , (24) [11] T. Mura an J. Itoh: Inetigation of Switching Lo Minimization for the Matrix Conerter Bae on Virtual AC/DC/AC Conerion Uing Space Vector Moulation, JIASC IEEJ, pp.i-637-i-64, (211) 2%