Three Electrics of New Energy Vehicles (Motor)
Today, with the booming development of the new energy vehicle industry, the research and development technology of new energy vehicles is constantly improving. As the three major parts of new energy vehicles, batteries, motors, and electronic controls determine the work of new energy vehicles. As the core of electric vehicles, motors are like the engines of traditional fuel vehicles, which directly determine the drive of electric vehicles.
Definition of Motor.
The drive motor is the core component of the drive device of new energy vehicles. It is used in various new energy vehicles and directly affects the performance of the whole vehicle. The motor of new energy vehicles is a machine that can convert the electrical energy of the power supply into mechanical energy and mechanical energy into electrical energy. When electrical energy is converted into mechanical energy, the motor exhibits the working characteristics of the motor; when mechanical energy is converted into electrical energy, the motor exhibits the working characteristics of the generator.
The motor consists of three parts: stator, rotor, and housing. The key points of motor technology are stator and rotor. It undertakes all functions related to the driving of new energy vehicles. The motor of new energy vehicles has forward and reverse rotation. Forward rotation means driving forward and reverse rotation means reversing. It also needs to have a wide speed regulation range and can act as a generator under energy recovery conditions.
Classification of motors.
There are four types of motors for new energy vehicles: DC drive motors, AC induction drive motors, AC permanent magnet synchronous drive motors, and switched reluctance drive motors. Among them, the AC permanent magnet synchronous drive motor is the most commonly used in new energy vehicles.
1. DC drive motor
The DC drive motor has good speed regulation performance, large starting torque, simple control, and low controller cost, but has low power density, large mass volume, and parts such as brushes and steering gears inside the motor are easy to wear, low reliability, and difficult maintenance. Therefore, the use rate of DC drive motors in electric vehicles is getting lower and lower.
2. AC induction drive motor
The AC induction drive motor has a simple structure, a solid structure, good reliability, and is very easy to maintain. However, the AC induction drive motor cannot be directly driven by DC power. A power converter is required to convert DC power into AC power with adjustable frequency and amplitude. The power converter will cause high-order harmonics and noise, and the AC induction motor has a large working current and lower energy utilization rate than the permanent magnet motor due to the existence of excitation current. Therefore, the use rate in domestic electric vehicles is not high.
3. AC permanent magnet synchronous drive motor
The AC permanent magnet synchronous drive motor has a permanent magnet rotor and no excitation coil. Compared with the induction motor, the rotor structure is more solid, the volume is smaller, the structure is simpler, and there is no excitation loss. The efficiency is high, the motor power density is large, and the mass and volume are small. The pulsation is small, the vibration is light, and it is not easy to generate noise. The sound is weak. At the same time, it has a wide weak magnetic range and high torque overload performance. Therefore, domestic new energy electric vehicles often use AC permanent magnet drive motors when selecting drive motors.
4. Switched reluctance drive motor
The switched reluctance drive motor has a very simple structure and very high reliability. The range of allowed errors is also large, and the control is simple and the controller cost is low. However, in actual use, the switched reluctance drive motor will generate a lot of noise, so very few cars use this drive motor.
For low-speed electric vehicles, DC motors are more commonly used. DC motors are also the earliest motors used in electric vehicles. However, with the development of electronic technology, mechanical manufacturing technology and automatic control technology, AC motors have shown better performance than DC motors, so they have gradually replaced DC motors.
Mechanical transmission device
Mechanical transmission device is a device that transmits the mechanical energy output by the motor to the wheels. Because motors generally have good speed regulation performance, current mechanical transmission devices are generally fixed-speed ratio reduction mechanisms, and no longer require a transmission.
At present, motors and mechanical transmission devices are basically electromechanically integrated, which can achieve higher transmission efficiency, better reliability, lighter weight, and smaller size.
