IEEE PEDS 2009 Safe-Commutation Strategy for Controlled Rectifier Operation using Single- Phase Matrix Converter S.Z.Mohammad Noor, R. Baharom,M.K.Hamzah, N.R.Hamzah Faculty of Electrical Engineering Universiti Teknologi MARA Shah Alam, Malaysia ctzaliha_mn@yahoo.com, mustafar@ieee.org ABSTRACT- THIS PAPER PROPOSES AN IMPLEMENTATION OF A NEW SAFE-COMMUTATION STRATEGY FOR CONTROLLED RECTIFIER OPERATION USING SINGLE-PHASE MATRIX CONVERTER (SPMC). THE PULSE WIDTH MODULATION (PWM) TECHNIQUE WAS USED TO CALCULATE THE SWITCH DUTY RATIO TO SYNTHESIZE THE OUTPUT. THE PROPOSED SAFE- COMMUTATION STRATEGIES WERE DEVELOPED THROUGH AN ARRANGEMENT OF COMMUTATION SWITCHES THAT ALLOWS DEAD TIME TO AVOID VOLTAGE SPIKES DUE TO INDUCTIVE LOAD. PRIOR TO ITS PRACTICAL REALIZATION A COMPUTER SIMULATION MODEL IS DEVELOPED TO INVESTIGATE THE BEHAVIOUR OF THE SPMC USING MATLAB/SIMULINK (MLS) AND PSPICE. AN EXPERIMENTAL TEST-RIG WAS THEN CONSTRUCTED TO VERIFY THE OPERATION; INCORPORATED WITH CONTROL ELECTRONICS, GATE DRIVES, AND POWER CIRCUITS. THE PERIPHERAL INTERFACE CONTROLLER (PIC 16F84A) WAS USED FOR DIGITAL CONTROL IMPLEMENTATION. SELECTED SIMULATIONS AND EXPERIMENTAL RESULTS ARE PRESENTED TO VERIFY PROPOSED OPERATION. Keyword: - Single Phase Matrix Converter (SPMC), Pulse Width Modulation (PWM), Safe-commutation, Rectifier I. INTRODUCTION The matrix converter is a modern power conversion topology, first introduced by Alesina and Venturini in 1980 [1, 2], representing the circuit as matrix matrix of bi-directional power switches. It is a force commutated converter which uses an array of controlled bidirectional switches as the main power elements to create a variable output voltage system with unrestricted frequency. There is presently considerable interest in matrix converter (MC) technology both in academic and industrial community [3]. One of the key benefits claimed for the matrix approach is the possibility of greater power density due to the absence of a DC link [4] in direct AC conversion. In addition, MC is able to operate in all the four quadrants of operation. These features make the matrix converter a suitable alternative to the traditional voltage source inverter [5]. However, the first 25 years in the development had been slow due to lack of understanding of the safe-commutation strategies. II. SINGLE-PHASE MATRIX CONVERTER The single-phase matrix converter (SPMC) was first realized by Zuckerberger et al. [6] in 1997, with other works on DC-AC (Inverter) by Hosseini et al. [7] in 2001, AC-AC by Saiful et al. [8] in 2002 and DC-DC conversion [9]. The SPMC as shown in Figure 1 consists of a matrix of input and output lines with four bidirectional switches connecting the single-phase input to the single-phase output at the intersections. Figure 1: SPMC circuit configuration III. COMMUTATION PROBLEM The commutation problem [10] is an important practical issue to be considered in the employment of matrix converter. Since there are no freewheel path, it is difficult to reliably commutate current from one switch to another. In consequence the switching must be theoretically instantaneous and simultaneous to prevent a load current interruption or a short circuit [11]. However, it is difficult to achieve a simultaneous commutation of controlled bidirectional switches in matrix converters without generating overcurrent or overvoltage spikes that in turn can destroy power semiconductors. These cause a conflict where switches should not both be ‘OFF’ at the same time since there is then no path for the inductive load current and to dissipate resulting in large overvoltages would destroy the switches [12]. This fact limits the practical implementation and negatively affected the interest in matrix converters [13]. PEDS2009 1026