High Efficiency IPM Motor Drives for Hybrid Electric Vehicles

In the 21^st century, global warming has become an important issue. Carbon dioxide (CO₂) gas emissions should be reduced to preserve the correct air quality as per Kyoto protocol, implemented on February 16, 2005 by most of the countries. Modern human beings, who enjoy the fruits of electric energy technologies for climate controlled home and work place environments via air conditioners/heat pumps, and mass transportation using cars as necessities, cannot put up with the inconveniences of the past. In order to maintain and develop this energy consuming technologies, availability of sustainable energy sources and their effective uses through efficiency improvements are of paramount importance. Power electronics and electric motor drives are the enabling technologies crucial for industrial competitiveness in the world market place. One of the most valuable achievements in power electronics is to introduce degree of freedom to variable frequency from the fixed value of the generated electrical power supplies. Over 60% of the generated energy is consumed by electric motors. Variable speed drive, which regulates the speed of the motor by controlling the frequency through smart uses of power electronics and control systems, can significantly reduce the energy consumption. Thus improvements in efficiency of the drive systems are the most effective measures to reduce primary energy consumption; and thereby reduce CO₂ gas emissions, which cause global warming. The objective of this paper is to provide a short introduction to the recent emergence of high efficiency and high performance interior permanent magnet (IPM) synchronous motors. Highlights of IPM motors include wide spread application in Japanese made hybrid electric vehicles to save precious electric energy, reduce gas emission and deter climate change.