Five-Phase Induction Motor Drive with Sine-Wave Filter Pawel Stec 1 , Jaroslaw Guzinski 2 , Patryk Strankowski 3 Gdansk University of Technology Faculty of Electrical and Control Engineering Gdansk, Poland 1 p.stec@ely.pg.gda.pl, 2 jarguz@pg.gda.pl, 3 strankowski@ely.pg.gda.pl Atif Iqbal 4 , Ahmad Anad Abduallah 5 , Haitham Abu-Rub 6 4, 5 Qatar University, 6 Texas A&M University at Qatar Doha, Qatar 4 atif2004@gmail.com, 5 anad.ahmad@gmail.com, 6 haitham.abu-rub@qatar.tamu.edu Abstract—The paper presents closed-loop ac drive with 5- phase induction motor operating with voltage source inverter and sine-wave filter. The motor supply voltages and currents have sinusoidal shape. For well known adjustable electric drives the field oriented control method with flux and speed control can be applied. In the presence of output filter both control and estimation algorithms should be modified due to sine-wave filter installation. The major advantage of the drive with speed observer is an operation without motor speed sensor based on inverter currents and voltage embedded sensors. In this paper sensorless operation of a five-phase induction motor drive with inverter output filter is accomplished. The validation of the drive operation was proved by simulation and experiments. The test bench was developed with prototype of 5-phase 4.3 kW induction motor and inverter with DSP control and sine-wave filter is designed and built. Keywords— multiphase drives, induction motor, sine-wave filter, vector control, state observer I. INTRODUCTION In recent years special attention is paid to multiphase electric motors and drives where the term ‘multiphase’ means more than 3 phases. Several research papers have been published on the subject of multiphase drive – the comprehensive review on development and up-to date technology could be found in [1]. Generally multiphase drives offer several advantages such as: higher torque density, lower torque pulsation and noise, better fault tolerance and reduction of rated current of power converter devices [1], [2]. Multiphase drives are especially suited for application in electric vehicles, rail traction, ship propulsion, aircrafts and in general high power systems and other reliable requested drives. The mature technology of 3- phase induction motor control is applicable to multiphase systems, e.g. field oriented control and sensorless control systems [1]-[4]. However, due to more complex structure of the multiphase motor some modification and extensions of the classical solutions are needed as proposed in [1], [2], [5]-[8]. The realization of the multiphase drive requires the use of multiphase converters. Numerous types of power converters ate used – from two level voltage source inverters (most popular) to multilevel voltage source inverters and matrix converters [9]. A lot of industrial drives with vector control can operate in the sensorless mode i.e. without speed measurement. Numerous speed estimation method exists, however, improvement and new algorithms for speed computation are still needed [2], [10]. Due to high dv/dt in voltage source PWM inverters the problems known from 3-phase drives will appear in multiphase drives as well. This includes: bearing currents, shaft voltages, insulation stress, efficiency reduction, noises etc. [11], [12]. From this follows that in many applications a passive filter is connected at the output of a PWM voltage source inverter. One of these filters is a sine-wave filter, described as low-pass filter, or simply LC filter which delivers the sinusoidal shape of the voltages and currents. With LC filer the motor supply voltage is close to sinusoidal shape. Unfortunately, the presence of LC filter at the output of inverter causes various problems for the control and estimation systems. The reason is that the actual motor voltages and currents differ from measured by the inverter embedded sensors. Hence, additional voltage and current sensors can be installed on output side of the filter. However, for system simplicity, if the filter is installed outside the inverter enclosure, additional voltage and currents sensors are not recommended. Furthermore, the speed sensor is eliminated in some of electric drives especially where long cable are used such as in downhole applications. Therefore, the LC filter installation in the drive requires modifications in the control and estimation process [2], [13]-[17] in order to achieve high performance control. In ac electric drives with filters only the solutions for 3-phase drives were presented, e.g. for field oriented control (FOC) [2], [13], nonlinear FOC [15], multiscalar control [14], [15], and for direct torque control (DTC) [17]. Fig. 1. Electric drive with 5-phase induction motor and sine-wave filter This paper try to presents speed sensorless FOC method for 5-phase induction motor with voltage source inverter and LC filter - Fig. 1. The FOC principle is used for motor control whereas the multiloop LC filter control is subordinated. A flux and speed observer with equations of the 5-phase motor and 1. The project was financed by the National Science Centre with funds allocated on the basis of the agreement No. DEC-2013/09/B/ST7/01642. 2. This publication was made possible by an UREP 12-031-2- 010 grant from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors. 978-1-4799-2399-1/14/$31.00 ©2014 IEEE 2111