Introduction to New Energy Vehicle Drive Motors
According to the working power supply of the motor, the motor can be divided into DC motor and AC motor.
AC motors can be divided into synchronous motors and asynchronous motors according to the speed consistency of the stator and rotor.
DC motors can be divided into brushed motors and brushless motors according to whether they have brushes or not.
Permanent magnet synchronous motor
With the improvement of the performance of permanent magnet materials and the reduction of costs, permanent magnet synchronous motors are gradually becoming one of the mainstream motors in electric vehicle drive systems due to their advantages such as high efficiency, high power factor and high power density.
The permanent magnet synchronous motor (PMSM) system has the characteristics of high control accuracy, high torque density, good torque smoothness and low noise.
By rationally designing the permanent magnet magnetic circuit structure, higher field weakening performance can be obtained and the speed regulation range of the motor can be improved. Therefore, it has high application value in electric vehicle driving.
Induction asynchronous motor
Induction asynchronous motors are a common type of AC motor characterized by a set of copper bars on the rotor that resemble a squirrel cage, hence the name squirrel-cage asynchronous motor.
This kind of motor usually consists of two parts: a stator and a rotor. The coils on the stator generate a rotating magnetic field, and the copper bars in the rotor induce current in this magnetic field, thereby generating torque. The advantages are simple structure, high reliability and low maintenance cost, so it is widely used in various industrial production scenarios.
Squirrel cage asynchronous motors have a wide power range, ranging from tens of watts to several megawatts, and can be adapted to the needs of different occasions.
However, induction asynchronous motors have large starting currents, relatively low efficiency, and are prone to noise and vibration at low speeds.
Hub motor
The wheel hub motor integrates the power, transmission and braking devices into the wheel hub. On the one hand, the chassis structure is simple and unified, which greatly saves space in the car, effectively improves transmission efficiency and saves energy significantly.
Another convenience is that by using in-wheel motors, vehicle manufacturers can reduce the number of parts and shorten the development cycle of new models.
Taken together, in-wheel motors have outstanding advantages in energy management and power deployment, and their management is more intelligent. Wheel hub drive technology is not yet mature but has certain advantages and may be an important development direction for the future new energy vehicle power system revolution.
Brushless DC motor
This kind of motor transfers the permanent magnets to the rotor, then places the electromagnets on the stator (shell), and uses an external motor controller to alternately switch the various excitation windings from positive windings to negative windings, thus eliminating the need for brushes and its maintenance, thereby generating a rotating magnetic field.
Its advantages are long service life, high efficiency and low maintenance costs. The disadvantages are that the initial cost is higher and the motor speed controller is more complex.
This type of motor is very popular in the market for small cars such as e-bikes and scooters, and is used in some assistive automotive applications such as electric power steering assist.
DC brushed motor
A DC motor allows DC current from the car's battery to be transferred to the rotor windings through spring-loaded carbon or lead "brushes" that power rotating contacts connected to the wire windings.
The advantages are low initial cost, high reliability, and the motor is easy to control. Changing the voltage can adjust the speed of the motor, change the current, and thereby control its torque. Disadvantages include lower brush and contact life and maintenance costs.
Therefore, except for some Indian Railway locomotives, this type of motor is rarely used in transportation. (Note: Now it is mostly used in remote control car models)
