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Electric Car Engine
The electric car engine, or more properly it's motor, is what propels the vehicle and (usually) what acts as a generator during regenerative braking. There are several types of motors used in electric cars - almost as varied as the cars are themselves.
DC Series Wound
These are common in smaller electric vehicles, such as neighborhood electrics (NEV) and golf carts. They are generally cheaper than other types, run on direct current, so little power is lost from the battery in conversion, and give full power and torque from 0 RPMs.
Their down-side is that they tend to lose power when under heavy loads, so they aren't the best hill climbing or weight-pulling option. These motors also have no rotation control devices built in, so when they are run without a load (hooked up to nothing substantial), they can literally tear themselves apart.
Permanent Magnet DC
These motors are generally more common now and have been for two or three years. These are most common in smaller vehicles like bicycles, scooters, and some motorcycles. Like the DC Series, these DC motors offer power savings in the form of less loss from battery to motor. Their down side is their noise.
While they don't have the other problems inherent in the Series Wound, they do have a major drawback: they make a lot of noise. The "whirring" you normally associate with an electric vehicle is often the PM DC's brushes doing their thing. This noise means lost energy and it means maintenance because anytime two things rub together, eventually one of them has to be replaced.
Phase AC Induction
For full-sized and performance-oriented electric vehicles, such as the Nissan Leaf or your trailer-pulling Tyrano truck, these are the motors being used. The AC means it's alternating current, so an inverter to convert the battery output to AC is required and that means power loss. The payoff is in the power gained thanks to this motor's capabilities.
A Phase AC has two major advantages over DC options: more power with smoother delivery and less noise (and the resulting loss). The AC motor produces full torque at 0 RPM, but is generally more controllable than are the DC options. It also performs better in terms of power output when under heavier loads, such as climbing hills or pulling trailers.
It's other advantage in this regard is its smooth rotation increases - it tends to take slightly longer to reach full rotations, so it is "smoother" to the feel and thus much more suited to being coupled to a transmission meant for an internal combustion engine. This makes it easier to couple with current technologies and to use as a retrofit option. These motors can also act as generators for regenerative braking.
Those are the three basic types of electric car motors you'll see in operation today. Nearly all automakers are using an Phase AC Induction type, but smaller vehicles and conversion kits often include one of the DC options instead because they are cheaper and easier for the DIY mechanic to install.
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