oa Five-Phase Sensorless Induction Motor Drives With Lc Filter For High Power Applications

Multi-phase IM drive systems are nowadays seen as a possible alternative to the three-phase drives due to their features that are especially suited for high power applications such as Oil & Gas industries, electric vehicles, traction drive, ship propulsion, robotics and mining and huge number of application. The main advantages of the multi-phase machines are higher power density with reduced volume, lower torque pulsation at higher frequency, lower dc link current harmonics and lower noise and keep going. This fault tolerance capability of the multi-phase machines makes them highly attractive for safety critical applications listed above. The trend in the drive industry is to employ sensorless topology to make the system more reliable, robust, lower hardware count, reduced cabling, reduced cost and less maintenance. The purpose of this paper is to design and develop five-phase speed sensorless induction motor drive system with inverter output LC filter. The drive system are supplied using PWM voltage source inverter and the growing switching speed of IGBTs pose additional problem of high dv/dt. The high dv/dt of the inverter output leads to several problems in the drive systems such as doubling of motor applied voltage (especially for drive with long cable), high voltage stress on motor, leakage and bearing currents leading to the bearing failure and high electromagnetic interference (EMI) etc. To mitigate these issues particularly passive filters are used. This paper focuses on using an LC filter at the output of the five-phase inverter. This paper investigate the design issues of output LC in conjunction with five-phase drive system. The LC filter causes delay and phase shift in the output voltages that affect adversely the motor control especially in sensorless vector controlled drive system. The presence of LC filter is to be incorporated in the speed estimator system. Hence the modification is necessary in the control structure. The effect of inverter output LC filter on the behavior of a sensorless vector controlled five-phase induction motor drive system investigated in this paper. Modification in the control structure and algorithm is implemented and will be reported in the full paper. The whole approach based on theoretical study, simulation verification and experimental implementation.