Extended Voltage Range AC Drive using a Z Source Indirect Matrix Converter Sérgio Sousa 1,2 , Sónia Pinto 2,3 , Fernando Silva 2,3 , José Maia 1,2 1 DEE, Escola Superior de Tecnologia de Setúbal, Campus do IPS, Setúbal, Portugal email: sergio.sousa@estsetubal.ips.pt ; jose.maia@estsetubal.ips.pt 2 CIEEE – Center for Innovation in Electrical and Energy Engineering, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal 3 DEEC, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal email: soniafp@ist.utl.pt ; fernandos@alfa.ist.utl.pt Abstract - In this paper, a control system for an Indirect Matrix Converter (IMC) with a Z source is proposed. This power topology and control is intended for the variable speed drive of a three phase induction motor. To maintain the low filtering needs of IMC, the z source inductors and capacitors values are sized to be similar to the input filter parameters. The resultant IMC has boost capabilities, thereby increasing the ac motor drive operating range, while keeping low harmonic content input currents. Several simulations on the proposed converter are performed, showing its capabilities and development potential, namely the possibility of using SPWM over its nominal range. Index Terms— motor drive, boost converter, indirect matrix converter, z source. I. INTRODUCTION The use of variable speed motor drives is a growing trend for manufacturing, extracting and automotive applications, guaranteeing high efficiencies, increased energy savings and higher versatility and flexibility. They can be found in high and low power applications, from electrical cars and household appliances, to locomotives and mining machinery. They may be fed by back to back converters or matrix converters. Back to back topologies have the disadvantage of bulky and usually expensive electrolytic capacitors, as opposed to matrix converters, which are nearly all-silicon converters with low filtering requirements [1][2]. However the output voltage of matrix converters is always lower than the input voltage, thereby having a “buck” characteristic [3][4], which can reduce the operating range of the load, in this case, a three phase asynchronous induction motor. There are several ways to cope with this issue, such as the use of a dc link boost converter, thereby losing all the advantages of the matrix converter, or the use of a three- phase step-up transformer. In this paper an alternative drive and control method of the indirect matrix converter (IMC) is proposed, in which a z network is used in the dc link to increase the dc link voltage, providing the three-phase induction motor with the necessary stator voltage in order to cope with its load requirements. However, to guarantee the low filtering requirements of an IMC, the z source inductance and capacitor values should be as low as possible. Although the use of a z network connected to the dc link of indirect matrix converters has been previously discussed [9][10], this work is focused on the closed loop control of the dc link voltage and the input/output currents: the rectifier stage is controlled so that the current vectors impose phase and amplitude control, thus guaranteeing near unity power factor. The inverter stage, along with a closed loop control of the ac three phase induction motor currents, also enforces specific operation modes, providing the necessary stator voltage, increasing the power flow from the mains to the load. The dc link voltage has a direct connection with the drive requirements, as they are related to the load torque and the rotor speed. Figure 1 – Indirect Matrix Converter proposed schematic 978-1-4673-0141-1/12/$26.00 ©2012 IEEE 951