Hardware Implementation of Multi-Phase Power Conversion using Matrix Converter

Transcription

1 Hardware Implementation of Multi-Phase Power Conversion using Matrix Converter B. Muthuvel Associate Professor, Department of Electrical & Electronics Engineering, AKT Memorial College of Engineering and Technology, Kallakurichi, Villupuram District, Tamil Nadu, India. Dr. T. S. Anandhi Associate Professor, Department of Instrumentation Engineering, Annamalai University, Annamalai Nagar, Cuddalore District, Tamil Nadu, India. Dr. P. Sivagnanam Principal, Krishnasamy College of Engineering and Technology, Kumarapuram, Cuddalore, Tamil Nadu, India. K. C. Balaji Assistant Professor, Department of Electrical and Electronics Engineering, Sree Sastha Institute of Engineering and Technology, Chembarabakkam, Chennai, Tamil Nadu, India. Abstract This paper proposes a new approach of hardware design and implementation of multi-phase power conversion using matrix converter. It includes the 3 phase to 3 phase, 3 phase to 5 phase and 3 phase to 9 phase power conversion using matrix converter in open loop configuration. In open loop, the power circuit was realized by bi directional IGBT switches so as to achieve high switching speed and low on state conduction losses. The performances of the multi-phase matrix converter are evaluated using RL Load. The matrix converter bidirectional switches are controlled by the Field Programmable Gate Array (FPGA) controller. It includes the Xilinx Spartan 3A DSP processor which is developed by the Xilinx incorporation. Keywords: 3 phase to 3 phase converter, 3 phase to 5 phase converter, 3 phase to 9 phase converter, Matrix converter, AC to AC conversion, Power conversion, Multi-phase converter. Introduction The matrix converter (MC) is a single-stage power converter, capable of feeding an m-phase load from an n-phase source without using energy storage components. It is a direct frequency conversion device that generates variable magnitude variable frequency output voltage from the ac line. It has high power quality and it is fully regenerative. Due to the increasing importance of power quality and energy efficiency issues, the Matrix converter technology has recently attracted the power electronics industry. Control and modulation techniques that enhance both the ac line and motor load side performance have been well developed. Recently, direct ac/ac converters have been studied in an attempt to realize high efficiencies, long lifetime, size reduction, and unity power factors. The benefits of using direct ac/ac converters are even greater for medium voltage converters as direct ac/ac converters do not require electrolytic capacitors, which account for most of the volume and cost of mediumvoltage converters. Due to the absence of energy storage elements, Matrix converter has higher power density than PWM inverter drives. However, for the same reason, the ac line side disturbances can degrade its performance and reliability. Therefore the matrix converter drive performance under abnormal input voltage conditions were introduced [1]. Timing errors in the switching between the series-connected switches cause a voltage imbalance in the snubber circuit and increase voltage stress. A new bidirectional switch with regenerative snubber to realize simple series connection for matrix converters was proposed [2]. A single-phase Z-source Buck-Boost matrix converter which can buck and boost with step-changed frequency, and both the frequency and voltage can be stepped up or stepped down was developed [3] To improve the output performance, a novel Z-source sparse matrix converter and a compensation method based on a fuzzy logic controller to compensate unbalanced input-voltages has been proposed [4]. An improved space vector modulation using amplitude coefficient on a capacitor-clamped multilevel matrix converter has been developed for the MMC that utilizes a multilevel structure on a conventional matrix converter, which allows direct ac-ac conversion without large energy store elements [5]. The matrix converter (MC) is a forced commutated power converter that directly connects input with output phases through fully controlled bidirectional switches based on power semiconductors [6]-[7]. Also MC having a capability of switch the current in both directions and 1883

2 block voltages in both directions. Due to open circuited switch failures, a fault diagnostic technique and Modified switch control schemes are introduced in Matrix Converters [8]. For reduction of switching losses, common-mode voltage control, spectrum regulation, additional modulation stages are needed [9]. In order to improve output performance under unbalanced voltage conditions, a z-source sparse matrix converter has been developed [10]. To reduce the cost and improve the reliability of the drive with any control strategy, modified venturini based direct matrix converters are introduced [11]. To achieve real time control with quick speed and fast response, new designs of controllers are needed. PI, Fuzzy and Hybrid controllers are proposed to sense the output continuously and correct the output at the instant if any disturbance occurred [12]-[14]. Phase conversions are needed due to Reducing the complexity of windings Size of the motor Easy winding replacement More saving of copper. voltage with desired frequency and amplitude can be controlled by the bi-directional switches. The bi-directional 3x3 switches (2 give 512 combinations of the switching states. But only 27 switching combinations are allowed to produce the output line voltages and input phase currents. The attractive characteristics of a Matrix converter are as follows: Sinusoidal input and output waveforms with minimal higher order harmonics and no sub harmonics; Controllable input power factor Bidirectional energy flow capability Compact design & Long life due to absence of a bulky electrolytic capacitor Unity input power factor at the power supply side For a 3 phase to 3 phase power conversion, Input filter is needed in order to eliminate the harmonic components of the input current and reduce the input voltage distortion supplied to the Matrix Converter as shown in fig. 2 In this paper, Hardware designed and implemented for the multi-phase matrix converter in open loop configuration feeding RL load. 3 Phase Input 3 Phase Auto T/F 3 Phase Isolation T/F Power Circuit of Matrix Converter Load FPGA Controller Figure 1: Basic block diagram of multi-phase Matrix converter The duty cycle calculation is taken into account for Maximum modulation index (MI) and the output is realized with the RL load. Hardware Implementation of multi-phase matrix converter includes the 3 phase to 3 phase, 3 phase to 5 phase and 3 phase to 9 phase power conversion. The proposed model is very simple, flexible, n number of output phase conversions and can be accommodated with any type of load. Fig. 1 refers the Basic block diagram of the proposed multiphase Matrix converter. Figure 2: Circuit scheme of 3 phase to 3 phase matrix converter. Matrix Converter The Matrix converter (MC) is a single stage direct ac to ac converter, which has an array of m x n bi-directional switches that can directly connect m phase voltage source into n phase load. A 3 phase matrix converter consists of 3x3 switches arranged in matrix form (3x5 for 5 phase and 3x9 for nine phase). The arrangement of bi-directional switches is such that any of the input phases R, Y, B is connected to any of the output phases a, b, c at any instant. The average output Figure 3: Circuit scheme of 3 phase to n phase matrix converter. 1884

3 Fig. 3 refers the schematic diagram of the 3 phase input into multiphase output matrix converter. Number of phases selection is based on the type of application. For a 5 phase output, output phases a, b, c, d, e are considered. For a 9 phase output, output phases a, b, c, d, e, f, g, h, i are considered. Nowadays 5 phase induction motors are available. When 3 phase to 3 phase matrix converter operated with 9 bidirectional switches, the following two basic rules have to be satisfied. Two or three input lines should not be connected to the same output line to avoid short circuit At least one of the switches in each phase should be connected to the output to avoid open circuit. The switching function of single switch as 1, switch SKj closed S Kj = { (1) 0, switch SKj opened Where, K = {a, b, c), j = {R, Y, B} The above constraints can be expressed by Saj + Sbj + Scj = 1, j = {R, Y, B} (2) With these restrictions, the 3 x 3 matrix converter has 27 possible switching states. A. Analysis of 3 phase to 3 phase Matrix converter. The input or source voltage vector of the 3 phase to 3 phase Matrix V im cos(ω i t) V R V i = [ VY ] = [ V im cos (ω i t + 2π ) 3 ] (3) V B V im cos (ω i t + 4π ) 3 The output voltage vector of the 3 phase to 3 phase Matrix V om cos(ω o t) V a V o = [ V b ] = [ V om cos (ω o t + 2π ) 3 ] (4) Vc V om cos (ω o t + 4π ) 3 The input or source current vector of the 3 phase to 3 phase Matrix I im cos(ω i t) I R I i = [ IY ] = [ I im cos (ω i t + 2π ) 3 ] (5) I B I im cos (ω i t + 4π ) 3 The output current vector of the 3 phase to 3 phase Matrix I om cos(ω o t) I a I o = [ I bc ] = [ I om cos (ω o t + 2π ) 3 ] (6) I om cos (ω o t + 4π ) 3 The relationship between output and input voltage is given as V o (t) = M (t). V i (t) (7) Where M t is the transfer Matrix and is given by M Ra M Ya M Ba M (t) = [ M Rb M Yb M Bb ] (8) M Rc M Yc M Bc where, M Ra = t Ra / T s, duty cycle switch S Ra, Ts is the sampling period. The input current is given by I in = M T I o (9) Duty cycle must satisfy the following condition in order to avoid short circuit on the input side. M Ra + M Ya + M Ba = 1 M Rb + M Yb + M Bb = 1 (10) M Rc + M Yc + M Bc = 1 The above condition is fulfilled by calculation of duty cycle. B. Analysis of 3 phase to 5 phase Matrix converter. The input or source voltage vector of the 3 phase to 5 phase Matrix V im cos(ω i t) V R V i = [ VY ] = [ V im cos (ω i t + 2π ) 3 ] (11) V B V im cos (ω i t + 4π ) 3 The output voltage vector of the 3 phase to 5 phase Matrix V om cos(ω o t) V o = V a V b Vc V d Ve ] = V om cos (ω o t + 2π 5 ) V om cos (ω o t + 4π 5 ) (12) V om cos (ω o t + 6π [ ) 5 [ V om cos (ω o t + 8π ) 5 ] The input or source current vector of the 3 phase to 3 phase Matrix I I im cos(ω i t) R I i = [ IY ] = [ I im cos (ω i t + 2π ) 3 ] (13) I B I im cos (ω i t + 4π ) 3 The output current vector of the 3 phase to 3 phase Matrix I om cos(ω o t) I o = I a Ib Ic I d Ie ] = I om cos (ω o t + 2π 5 ) I om cos (ω o t + 4π 5 ) (14) [ I om cos (ω o t + 6π ) 5 [ I om cos (ω o t + 8π ) 5 ] The relationship between output and input voltage is given as V o (t) = M (t). V i (t) (15) Where M t is the transfer Matrix and is given by M Ra M Ya M Ba M Rb M Yb M Bb M (t) = M Rc M Yc M Bc (16) M Rd M Yd M Bd [ M Re M Ye M Be ] where, M Ra = t Ra / T s, duty cycle switch S Ra, Ts is the sampling period. The input current is given by I in = M T I o (17) Duty cycle must satisfy the following condition in order to avoid short circuit on the input side. M Ra + M Ya + M Ba = 1 M Rb + M Yb + M Bb = 1 M Rc + M Yc + M Bc = 1 (18) M Rd + M Yd + M Bd = 1 M Re + M Ye + M Be = 1 The above condition is fulfilled by calculation of duty cycle. 1885

4 C. Analysis of 3 phase to 9 phase Matrix converter. The input or source voltage vector of the 3 phase to 9 phase Matrix V V im cos(ω i t) R V i = [ VY ] = [ V im cos (ω i t + 2π ) 3 ] (19) V B V im cos (ω i t + 4π ) 3 The output voltage vector of the 3 phase to 9 phase Matrix V om cos(ω o t) V o = V a V b Vc V d Ve V f V g V h Vi ] [ = V om cos (ω o t + 2π V om cos (ω o t + 4π V om cos (ω o t + 6π V om cos (ω o t + 8π V om cos (ω o t + 10π V om cos (ω o t + 12π V om cos (ω o t + 14π [ V om cos (ω o t + 16π ) 9 ] (20) The input or source current vector of the 3 phase to 9 phase Matrix I I im cos(ω i t) R I i = [ IY ] = [ I im cos (ω i t + 2π ) 3 ] (21) I B I im cos (ω i t + 4π ) 3 The output current vector of the 3 phase to 9 phase Matrix I om cos(ω o t) I o = [ I a Ib Ic I d Ie If I g I h Ii ] = I om cos (ω o t + 2π I om cos (ω o t + 4π I om cos (ω o t + 6π I om cos (ω o t + 8π I om cos (ω o t + 10π I om cos (ω o t + 12π I om cos (ω o t + 14π [ I om cos (ω o t + 16π ) 9 ] (22) Where, ω i frequency of input voltage and ω o -frequency of output voltage The relationship between output and input voltage is given as V o (t) = M (t). V i (t) (23) Where M t is the transfer Matrix and is given by M Ra M Ya M Ba M Rb M Yb M Bb M Rc M Yc M Bc M Rd M Yd M Bd M (t) = M Re M Ye M Be M Rf M Yf M Bf M Rg M Yg M Bg M Rh M Yh M Bh [ M Ri M Yi M Bi ] (24) where, M Ra = t Ra / T s, duty cycle switch S Ra, Ts is the sampling period. The input current is given by I in = M T I o (25) Duty cycle must satisfy the following condition in order to avoid short circuit on the input side. M Ra + M Ya + M Ba = 1 M Rb + M Yb + M Bb = 1 M Rc + M Yc + M Bc = 1 M Rd + M Yd + M Bd = 1 M Re + M Ye + M Be = 1 (26) M Rf + M Yf + M Bf = 1 M Rg + M Yg + M Bg = 1 M Rh + M Yh + M Bh = 1 M Ri + M Yi + M Bi = 1 The above condition is fulfilled by calculation of duty cycle. FPGA Controller The Field Programmable Gate Array Controller is referred as FPGA controller. A PWM generation is carried out by the FPGA controller which includes the Xilinx Spartan 3A DSP processor. The main advantages of algorithm implementation using FPGAs are Low manufacturing Cost Efficiency High data throughput Architecture Ability to modify Update of algorithm Reduced system complexity Improved performance An FPGA controller is a semiconductor device consisting of programmable logic components called logic blocks and programmable interconnections. Logic blocks are to have the function of basic logic gates. Logic blocks and interconnections are to be programmed by the designer after the FPGA is manufactured. Hence it is called field programmable. Xilinx FPGA is a commonly used programmable device. The Xilinx development tool converts the design idea into a configurable data file which could be loaded into Xilinx FPGA. It is a fully integrated tool set that allows users to access design entry, synthesis, implementation and simulation tools in a ready to use package. It also supports standard hardware description language (HDL) design. 1886

5 the controlled voltage is fed to the output load. The bidirectional switching sequences are programmed in FPGA controller using personal computer. For 3 phase (a, b, c), 3 3 =9 switches are activated. 3 switches in a phase and one switch at a time. For 5 phase (a, b, c, d, e), 3 5 =15 switches are activated. 5 switches in a phase and one switch at a time. Figure 4: Block diagram of 3 phase PWM Generator. For 9 phase (a, b, c, d, e, f, g, h, i), 3 9 =27 switches are activated. 9 switches in a phase and one switch at a time. Figure 5 shows the entire hardware module setup of multiphase converter and figure 6 shows the prototype model of the proposed multiphase converter hardware setup. Figure 7 shows the IGBT based bidirectional switches gate drive circuit. Figure 8 shows the Spartan 3A DSP processor based FPGA Controller kit which was developed by the Xilinx Corporation. Figure 9 shows the average output voltage of the multiphase converter feeding RL load. The output was tested with the load value of R=225 Ω and L=120mH. A. PWM Generation using Xilinx FPGA In Xilinx FPGA controller, gates interconnections using software are defined through SRAM or ROM. This provides flexibility to modify the designed circuit without altering hardware part. Figure 4 shows the overall block diagram of the 3 phase PWM generator. The carrier wave is compared with the multiplied modulating signal from the look up table. The data are stored in the internal ROM unit. The external multiplicand and the stored data will determine the modulation index (MI) of the PWM. The data stored in the look up table (ROM) consists of 60 data from R phase and another 61 data from B phase and data of Y phase is derived using addition of R and B phase using selector unit and multiplexer is used to select the required signal to the appropriate channel as to form a proper PWM output. Shifting of the signal waveform is essential so s to vary the power factor of the system. This is carried out by delay or advance of the reset signal. The reset signal is tied up to the entire module. A positive triggering edge during positive and negative cycles is used as a reference by the reset signal. Advancing or delaying the reset signal by the external command will force the current in the main circuit to lead or lag the voltage supply. Figure 5: Hardware module setup of multiphase matrix converter Hardware setup The hardware setup consists of 3 phase Auto transformer, 3 phase isolation transformer, 9 phase matrix converter kit, FPGA controller kit, load and Personal computer. The 3 phase power supply is stepped down to 110v using Auto transformer and fed to the isolation transformer for isolation purpose. The isolated 3 phase voltage is supplied to the 3 phase to multi phase converter module and the input voltage is controlled by the 27 independent IGBT based bidirectional switches (for 9 phase). All the bidirectional switches are controlled by the Xilinx Spartan 3A DSP processor based FPGA Controller and Figure 6: 3 phase to 9 Phase Matrix converter hardware kit. 1887

6 Hardware Results and Discussion The hardware results of multi-phase power conversion is carried out using storage oscilloscope and the amplitude of 5v scale in each channel with a time limit of 5 m. sec. The scaling factor of impedance probe is 1 and the impedance value is 1M Ω. The output is realized with passive RL load for R= 225 Ω and L= 120 mh. The hardware output comprises of three sections. Figure 7: Hardware setup of Gate drive circuit in Matrix converter A. Hardware output of 3 phase to 3 phase Matrix converter in Open loop configuration with RL Load. Fig. 10 shows the Input voltage waveform of R, Y, B phases. Fig. 11 shows the ZCD output waveform of R, Y, B phases. Fig. 12 shows the Composite waveforms of 3 phase ZCD outputs. Fig. 13 shows the waveform of Y phase ZCD output with a reference of R Phase. Fig. 14 shows the PWM generation output waveform of a, b, c phases. Fig. 15 shows the Output waveform of a phase and b phase. Fig. 16 shows the Output waveform of b phase and c phase. Fig. 17 shows the Output waveform of a phase and c phase. Fig. 18 shows the Average output voltage waveform of a, b, c phases. Figure 8: Xilinx Spartan 3A DSP processor FPGA Controller kit Figure 10: Input voltage waveform of R, Y, B phases Figure 9: Hardware output of Matrix converter using CRO. Figure 11: ZCD output waveform of R, Y, B phases. 1888

7 Figure 12: Composite waveforms of 3 phase ZCD outputs. Figure 15: Output waveform of a phase and b phase. Figure 13: Waveform of Y phase ZCD output with a reference of R Phase. Figure 16: Output waveform of b phase and c phase. Figure 14: PWM generation output waveform of R, Y, B phases. Figure 17: Output waveform of a phase and c phase. 1889

8 Figure 18: Average output voltage waveform of a, b, c phases. Figure 21: Output waveform of a phase and c phase. B. Hardware output of 3 phase to 5 phase Matrix converter in open loop configuration with RL Load. Fig. 19 shows the Input voltage waveform of R, Y, B phases. Fig. 20 shows the Output waveform of a phase and b phase ( a phase as reference). Fig. 21 shows the Output waveform of a phase and c phase. Fig. 22 shows the Output waveform of a phase and d phase. Fig. 23 shows the Output waveform of a phase and e phase. Figure 22: Output waveform of a phase and d phase. Figure 19: Input voltage waveform of R, Y, B phases. Figure 23: Output waveform of a phase and e phase. Figure 20: Output waveform of a phase and b phase ( a phase as reference). C. Hardware output of 3 phase to 9 phase Matrix converter in Open loop configuration with RL Load. Fig. 24 shows the Input voltage waveform of R, Y, B phases. Fig. 25 shows the Waveform of Y phase ZCD output with a 1890

9 reference of R Phase. Fig. 26 shows the PWM generation output waveform of R, Y, B phases. Fig. 27 shows the Output waveform of a phase and b phase. Fig. 28 shows the Output waveform of c phase and d phase. Fig. 29 shows the Output waveform of e phase and f phase. Fig. 30 shows the Output waveform of g phase and h phase. Fig. 31 shows the Output waveform of i phase and a phase. Figure 27: Output waveform of a phase and b phase. Figure 24: Input voltage waveform of R, Y, B phases. Figure 28: Output waveform of c phase and d phase. Figure 25: Waveform of Y phase ZCD output with a reference of R Phase. Figure 29: Output waveform of e phase and f phase. Figure 26: PWM generation output waveform of R, Y, B phases. 1891

10 Figure 30: Output waveform of g phase and h phase. Figure 31: Output waveform of i phase and a phase. Conclusion Hardware design and implementation of Multi-phase conversion using Matrix converter has been presented in this paper. Multi phase conversion includes the 3 phase to 3 phase, 3 phase to 5 phase and 3 phase to 9 phase power conversion. An IGBT is used as a bidirectional switch so as to achieve fast switching speed and reduced conduction losses. The output was realized by RL load and the hardware results are taken for maximum Modulation Index. The matrix converter IGBT based bidirectional switches are controlled by the Field Programmable Gate Array (FPGA) controller which includes the Xilinx Spartan 3A DSP processor. The hardware output results are satisfactory and the future extension of this paper is possible for three phase to n phase Matrix converter with various passive loads and different modulation index. References [1] Jun-Koo Kang, Hidenori Hara, Ahmet M. Hava, Eiji Yamamoto, Eiji Watanabe, and Tsuneo Kume, The matrix converter drive performance under abnormal input voltage conditions, IEEE Transactions on Power Electronics, Vol. 17, No. 5, September [2] Jun-Ichi Itoh and Ken-Ichi Nagayoshi, A new Bidirectional switch with regenerative snubber to realize simple series connection for matrix converters, IEEE Transactions on Power Electronics, Vol. 24, No. 3, March [3] Minh-Khai Nguyen, Young-Gook Jung, Young- Cheol Lim and Young-Min Kim, A single phase Z-source Buck-Boost matrix converter, IEEE Transactions on Power Electronics, Vol. 25, No. 2, February [4] Kiwoo Park, Kyo-Beum Lee and Frede Blaabjerg, Improving output performance of a Z-source sparse matrix converter under unbalanced input-voltage conditions, IEEE Transactions on Power Electronics, Vol. 27, No. 4, April 2012 [5] Xu Lie, Li Yongdong, Wang Kui, Jon C. Clare and Patrick W. Wheeler, Research on the amplitude coefficient for multilevel matrix converter space vector modulation, IEEE Transactions on PowerElectronics, Vol. 27, No. 8, August [6] René Vargas, Student Member, IEEE, Ulrich Ammann, Member, IEEE, andjosé Rodríguez, Senior Member, IEEE Predictive approach to Increase Efficiency and Reduce Switching Losses on Matrix Converters, IEEE Transactions on Power Electronics, VOL. 24, NO. 4, April 2009 [7] Andreas Ecklebe, Member, IEEE, Andreas Lindemann, Senior Member, IEEE, and Sebastian Schulz, Student Member IEEE Bidirectional Switch Commutation for a Matrix Converter Supplying a Series Resonant Load IEEE Transactions on Power Electronics, VOL. 24, NO. 5, May 2009 [8] Sangshin Kwak, Member, IEEE Fault-Tolerant Structure and Modulation Strategies With Fault Detection Method for Matrix Converters IEEE Transactions on Power Electronics, VOL. 25, NO. 5, May 2010 [9] Ren e Vargas, Member, IEEE, UlrichAmmann, Member, IEEE, Boris Hudoffsky, Jose Rodriguez, Senior Member, IEEE, and Patrick Wheeler, Member, IEEE Predictive Torque Control of an Induction Machine Fed by a Matrix Converter With Reactive Input Power Control IEEE Transactions on Power Electronics,, VOL. 25, NO. 6, June 2010 [10] Kiwoo Park, Student Member, IEEE, Kyo Beum Lee, Senior Member, IEEE, and Frede Blaabjerg, Fellow, IEEE Improving Output Performance of a Z-Source Sparse Matrix Converter Under Unbalanced Input Voltage Conditions IEEE Transactions on Power Electronics, VOL. 27, NO. 4, April 2012 [11] Brahim Metidji, Member, IEEE, Nabil Taib, Lotfi Baghli, Senior Member, IEEE, Toufik Rekioua and Seddik Bacha, Member, IEEE Novel Single Current Sensor Topology for Venturini Controlled Direct Matrix Converters IEEE Transactions on Power Electronics, VOL. 28, NO. 7, July

11 [12] B. Muthuvel, T. S. Anandhi, K. Ramash kumar and M. Jananiraj, A Design and Implementation of Hybrid Controller for 3 Phase to 3 Phase Power Conversion using Matrix Converter, International Journal of Applied Engineering Research ISSN Volume 10, Number 20 (2015) pp Research India Publications. [13] B. Muthuvel, T. S. Anandhi, P. Sivagnanam and K. Ramash kumar, Simulation of 3 Phase to 3 Phase Power Conversion Using Matrix Converter with Maximum and Minimum Voltage Transfer Ratio, International Journal of Engineering Research and applications (IJERA) ISSN: , Vol. 5, Issue 11, (Part-2) November [14] B. Muthuvel, T. S. Anandhi and M. Jananiraj, Simulation of Closed Loop Fuzzy Logic Controller for a 3 Phase to 3 Phase Power Conversion Using Matrix Converters, International Journal of Scientific Engineering and Research (IJSER) ISSN (Online): , Volume 4 Issue 1, January 2016 (PP 5-11), Paper ID: IJSER