The electric motor is the driving force of any electrically-powered vehicle. Electricity is fed to the motor and converts electrical energy to mechanical energy, the latter of which provides the instant thrust that people love in electric vehicles. There are two main types of motors for EV applications: AC (alternating current) and DC (direct current), although both motors serve the same purpose and are operating on the same principles. Both AC and DC motors feature a stator and rotor, and both work through the interaction of magnetic fields generated by the stator and the current flowing in the rotor.
However, the difference is in the power supply, or how electricity is fed to the electric motor. In terms of cost, DC motors and controllers are cheaper in exchange for more weight. Also, DC motors are less efficient for performance applications like in modern electric cars. DC motors are generally categorized as brushed DC motors and brushless DC motors. The former has ‘brushes’ that supply current to the rotor, while the latter has a permanent magnet rotor (hence the ‘brushless’ appellation). BLDC (Brushless Direct Current) motors are more durable and are capable of operating at 85-90% efficiency while having the capability to work at higher speeds.
Meanwhile, AC motors or PMSM (Permanent Magnet Synchronous Motors) are smaller and lighter than DC motors. AC motors are also known for producing higher torque, better performance, and performing at a higher efficiency than brushless DC motors. PMSM motors are also more reliable, quieter, and dissipate more heat while remaining suitable for both low and high-speed operations, making it the default choice for modern OEM electric vehicles.
But the AC motor or PMSM is not perfect. There are certain drawbacks to consider, as well. A typical AC motor requires a more complex and typically more expensive controller. In a PMSM motor, the controller not only regulates the flow of electrons, but it also converts the DC from the battery pack to AC, hence the added cost.
Electric motor maintenance is also a key factor, although brushless DC and AC motors require almost zero maintenance. Forklifts, golf carts, and electric scooters fitted with brushed DC motors may require frequent maintenance under certain operating conditions. The brush surface should remain smooth, shiny, and devoid of chips and/or cracks. Examining the brush shape is also important as it should conform to the shape of the commutator. More importantly, make sure the brush is not too short is worn down. If the brush is down to 1/4th of its original length, replace the brushes.
Cloud Electric is a proud supplier of electric motors for a wide array of vehicle applications. We carry a large inventory of brushed and brushless PMSM and DC motors from the best brands like Mars, D&D, FSIP, AMD, Kelly, and Inmotion.