Types of Electric Motors Used in Hybrid Cars

by David Eiranova
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Image by Flickr.com, courtesy of Powi) (Per Ola Wiberg

Hybrid cars represent the first popularly accepted wave of transportation technology improvements aimed at a greener future, and it is thanks to the advanced technology of electric engines that the car's consumer friendly characteristics are available at affordable prices. Hybrids, which have both an internal combustion engine and an electric motor, successfully combine their two power plants to achieve city mileage approaching 50 mpg and to get great highway mileage as well.


Electric motors are designed to convert electrical energy to kinetic energy, thus harnessing the supply of electrical power to use for mechanical tasks. There are two kinds of electrical motors--those that run with DC (direct current), and those that run on AC (alternating current). Both kinds rely on electromagnetism to create electromagnetic fields that interact with another magnet to produce motion.

Types of Electric Motors

Hybrids are generally found with AC motors, of which three types are used--the permanent magnet type, the three-phase induction type and the multi-phase (greater than three) induction type. Each type has its advantages and disadvantages. For example, the permanent magnet electric motor is ideal for a series hybrid like the Prius, but requires a cooling system that adds weight. A three-phase electric motor can be air-cooled but requires a more complex transmission. The recent development of the Chorus Meshcon multi-phase electric motor seems to have solved the main problem facing electric motors used in hybrids, specifically their inability to offer operation at low speed with high torque while maintaining the capacity for high-speed operation as well.


The electric motor in a hybrid car serves a dual purpose; it not only provides torque to drive the wheels, but when the car is braking, the electric motor becomes a generator and charges the batteries. Hybrids use their electric motors in conjunction with an internal combustion engine (ICE) that charges the batteries and also is part of the drive train of the car. Often the hybrid car will derive power from both the electric and ICE at the same time, while sometimes power is supplied by the electric motor only, which results in a very quiet ride.


The main benefit derived from hybrids is very high gas mileage. Because the ICE doesn't run all the time and some of the energy spent moving the car is recaptured during braking, hybrids have better city mileage than highway mileage, in some cases approaching 50 mpg for city driving.


Hybrid cars save money: switching from driving a Mazda 3 to a Toyota Prius will save $466 a year for drivers who drive 12,000 miles per year at a cost of $2.50 per gallon, according to the Gas Mileage Impact Calculator at hybridcars.com. But more important, hybrid cars are good for the environment. In the example above, switching to a hybrid will mitigate 3,538 pounds of CO2 emissions annually. Carbon dioxide is recognized as a greenhouse gas that is contributing to the climate changes the world is now experiencing.

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