Before the latest incarnation of electric vehicles, cars already used BLDC motors for windshield wipers, CD players, and power windows. Today’s automakers use three different types of electric motors in green cars: the BLDC motor, brushed DC motor, and AC induction motor.
The BLDC motor has a permanent-magnet rotor surrounded by a wound stator. The winding in the stator get commutated electronically, instead of with brushes. This makes the the BLDC motor:
- Simpler to maintain,
- More durable,
- 85%–90% more efficient,
- Able to respond faster and at higher operating speeds,
- Simpler to control in regard to speed control and reversing,
- Less prone to the failures that brushed motors experience, and
- Able to self-start.
The composition of the BLDC motor also keeps the machinery inside a vehicle cooler and thermally resistant. Plus, because the motor is brushless, there is no dangerous brush sparking.
The BLDC Motor Drive
All of today’s hybrid vehicles use a BLDC motor. Green car manufacturers often prefer BLDC motors over the alternatives because the peak point efficiency is higher and rotor cooling is simpler. The motors can also operate at “unity power factor,” meaning the drive can operate at its maximum efficiency levels.
Batteries and brakes. One of the most important components of the BLDC motor drive system is the batteries. In addition to supplying energy to the engine, they allow the electrical receivers to function. Therefore, it’s important that the batteries in green cars be as efficient as possible.
Whenever a battery gets used, an irreversible change in the chemical structure occurs. As a result, a rechargeable battery is most efficient when maintained close to full charge. Thanks to the permanent magnets in the brushless DC motor and the ability for the external torque to work as a generator, a person operating a green car can pulse-charge the battery by applying the brakes. It’s important to note, however, that braking alone won’t fully charge an electric car’s battery.
Motor response. Green car manufacturers and entities like NASA prefer BLDC motors because of their fast motor responses. The high-performance, small-diameter magnetic rotors reduce the inertia of the armature, allowing high acceleration rates, a reduction in rotational losses, and smoother servo characteristics. This optimal motor response also allows for more constant speeds, instant speed regulation and a quieter drive system.