What are the types of automotive motors in the era of new energy vehicles

The era of new energy vehicles has come, and its popularity has soared. Today, I will briefly introduce the types, advantages and disadvantages of new energy vehicles.

1. DC motor

A DC motor allows the DC current from the car battery to be transmitted to the rotor windings through spring-loaded carbon or lead "brushes". This part of the "brushes" provides energy for the rotating contacts connected to the wire windings. Each time it rotates a few degrees, the brushes power a new set of contacts. When the motor shaft of the car rotates, it will successively cause the polarity of the electromagnet on the rotor to reverse.

The housing surrounding the electromagnetic windings of the rotor has permanent magnets. The advantage is that the initial cost is lower, the reliability is higher, and the motor is easy to control. Changing the voltage can adjust the speed of the motor, and it can also change the current, which in turn controls its torque. Disadvantages include lower service life and the cost of maintaining brushes and contacts. Therefore, except for some Indian railway locomotives, this type of motor is rarely used in transportation.

2. Brushless DC motor

This kind of motor transfers the permanent magnet to the rotor, and then places the electromagnet on the stator (housing). It also uses an external motor controller to alternately switch the various excitation windings from the positive winding to the negative winding, and the brush and its Maintenance is eliminated, which in turn generates a rotating magnetic field.

The advantages are long service life, high efficiency and low maintenance costs. The disadvantage is that the initial cost is higher and the motor speed controller is more complicated. Generally, three Hall-effect sensors are required to correctly determine the phase of the stator winding current. The switching of the stator windings causes torque pulsation, and the transmitted torque increases and decreases periodically. This type of motor is very popular in the small car market such as electric bicycles and scooters, and is used in some auxiliary car applications, such as electric power steering assistance.

3. Permanent magnet synchronous motor

Physically, BLDC and PMSM motors look the same. Both have permanent magnets on the rotor and field windings in the stator. The difference is that PMSM does not use direct current and periodically opens and closes various windings, and then allows the permanent magnet to rotate and operate under continuous sinusoidal alternating current. It means that there is no torque fluctuation, and only a Hall effect sensor is needed to determine the rotor speed and position, so it is more efficient.

The advantage lies in its power density and strong starting torque. The disadvantage is that back-EMF will be generated when the power supply is not high-speed, which will cause resistance and heat to demagnetize the motor. This kind of motor plays a part in the power steering and braking system of automobiles, and has become the first choice for motor design of most battery electric vehicles and hybrid electric vehicles.

By Jessica