TECH UPDATE
Permanent Magnet & Induction Motors for Electric Vehicle Electric vehicles are gaining ground and many automo ve companies are launching their electric cars. It is expected that in future electric vehicles will be the main mode of transporta on. These vehicles are cleaner and more efficient as they have less number of moving parts than IC engine vehicles. They run on electric drive systems, electric motor, which converts electrical energy into mechanical energy, is the major part of the propulsion subsystem of the electric drive systems. Induc on Motor is one such type of motor which is popular in electric vehicles. It is followed closely by Permanent Magnet motors. Well known electric car Tesla model S relies on induc on motor while motor in Nissan Leaf and recently unveiled Porche’s Turismo concept vehicle is permanent magnet synchronous motor.
Image Courtesy of New Energy and Fuel.com
Induc on motors have benefits like low cost, high reliability and maintenance-free opera on. It is an asynchronous type of motor so the rotor always rotates at a lower speed than the magne c field. It relies on electric current to turn the rotor and produce torque. The electric current is generated through electromagne c induc on from the magne c field of the stator windings. Induc on motors can be used without a variable frequency drives (VFD) and are also cheap to manufacture. However, conven onal control of induc on motor such as variable voltage, variable frequency cannot provide the desired performance and they also suffer from lower efficiency as well as power density compared to their permanent magnet counterparts. Permanent magnet synchronous motors are thus gaining popularity due to high power density, compactness and current availability of power electronics needed for effec ve control. Also, these motors are designed to be more powerful while also having a lower mass and lower moment of iner a, high torque-to-current ra os, high power-to-weight ra os, and robustness.
According to an Allied Market Research, the world PMSM market is likely to generate revenue of $31.1 billion by 2022, growing at a CAGR of 10.9% from 2016 to 2022. Asia-Pacific is expected to dominate the PMSM market in terms of revenue as well as volume. PG.26 | Smart Automo ve | May - Jun 2018
The permanent magnet synchronous motor has features of both induc on motor and brushless DC motor. Like a brushless DC motor, it has a permanent magnet rotor and windings on the stator. However, the stator structure with windings resembles that of an induc on motor. Permanent magnet synchronous motor relies on magnets to turn the rotor, which spins at the same speed as the PMSM’s internal rota ng magne c field. They cannot run without a drive and a VFD is required to precisely control the speed of the PMSM to meet the applica on requirements for pressure, flow, volume, etc. Permanent magnet motor solu ons thus tend to have a higher ini al cost, despite recent increases in the price of permanent magnets, they are s ll profitable. www.telema cswire.net I www.coe-iot.com
