Multiphase Induction Motor Drives for Gear-Less Electric Vehicle Applications

Qatar has some major research priorities, targeting; reducing carbon footprints, developing smart cities and smart grids; and these demand high deployment of electric cars in near future. Qatar is an highly progressive country adopting to new evolving technologies at a fast pace. The proposed project is aimed at the development of a robust, highly reliable, efficient and wide speed range multiphase motor drive system that falls within the right context of the current research priorities of the Qatar University and the State of Qatar. The idea here is to use pole phase modulation technique to enhance the speed-torque control region of a multiphase motor drive system so that gear-less opeartion can be achieved in EV. Advantages and Disadvantages of the proposed pole phase modulated IM drives:  In high pole operation, the PPMIM drive is able to supply the high initial torque for fast acceleration and hill climbing.  The rated torque of the PPMIM drive in the high pole is k times greater than the low pole mode. For example, in 3-phase 12-pole mode, the 9-phase PPMIM drive is able to supply 3 times of the rated torque as comparted to 9-phase 4-pole mode.  In low pole mode, the PPMIM drive is able to supply high speed which is k times greater than the high pole mode.  The PPMIM drives are capable to generate 3 or 4 speed and torque variations. So, the mechanical gearbox system in conventional IC Engine based vehicles can be eliminated with the PPMIM drives, which will reduce the size and weight of the vehicle. Even though the PPMIM drives have several advantages (as mentioned above), on the other side they have a few disadvantages also such as:  To achieve the high starting torque in high power applications, the PPMIM drives has to operate in high pole and low phase mode, which magnifies the magnitude of space harmonics in the air gap.  The magnetizing inductance of the machine is inversely proportional to the square of the number of poles, which lowers the power factor.