The electric motor, power battery, and electronic control system of new energy vehicles are collectively known as the three core components of new energy vehicles, and the three are collectively referred to as the three-electric system.
I. Electric Motor
Electric motors are the power source for new energy vehicles. Based on their structure and principle, electric motors can be divided into three types: DC drive, permanent magnet synchronous, and AC induction. Different types of motors have different characteristics.
1. DC drive motor: Its stator is a permanent magnet, and the rotor is powered by direct current. As we know from junior high school physics, a current-carrying conductor in a magnetic field will experience an Ampere force, which causes the rotor to rotate. The advantages of this type of motor are lower cost and lower requirements for the electronic control system, while the disadvantages are that it is relatively large and has relatively weak power performance. Generally, low-end pure electric mobility vehicles use DC motors.
2. Permanent Magnet Synchronous Motor: This is essentially a DC motor, so its working principle is the same as a DC motor. The difference lies in the current input: a DC motor uses a square wave current, while a permanent magnet synchronous motor uses a sinusoidal wave current. The advantages of a permanent magnet synchronous motor are high power performance, excellent reliability, and relatively small size. The disadvantages are relatively high cost and certain requirements for the electronic control system.
3. Induction Motor: The principle is more complex than the previous two, but it can be roughly divided into three steps: First, alternating current is applied to the three-phase windings of the motor, generating a rotating magnetic field. Next, the rotor, composed of closed coils, cuts magnetic lines of force in the rotating magnetic field, generating an induced current. Finally, the movement of charges in the magnetic field generates a Lorentz force, causing the rotor to rotate. Because the magnetic field in the stator rotates before the rotor rotates, the induction motor is also called an asynchronous motor.
II. Power Battery
Power batteries are the energy source for driving motors. Currently, power batteries are mainly distinguished by positive and negative electrode materials, including lithium cobalt oxide, ternary lithium, lithium manganese oxide, and lithium iron phosphate. Ternary lithium and lithium iron phosphate batteries are more commonly used in new energy vehicles.
Lithium iron phosphate batteries have the advantages of low cost, good stability, and long lifespan, but the disadvantages of low energy density and significant range loss in winter. Ternary lithium batteries, on the other hand, have the advantage of low energy density, but the disadvantages of relatively poor stability and lifespan.
III. Electrical Control System
The term "electronic control system" is actually a general term, which can be further divided into vehicle control system, motor control system, and battery management system. A key characteristic of new energy vehicles is that the various electronic control systems are closely interconnected. In some vehicles, a single electronic control system controls all electrical equipment on board, so it's acceptable to refer to them collectively.
Since the three-electric system (battery, motor, and electronic control system) is a key component of new energy vehicles, if it is damaged, the cost of repair or replacement will undoubtedly be very high. Therefore, some automakers offer lifetime warranties for the three-electric system. Of course, the three-electric system is not that easy to break, which is why automakers dare to offer lifetime warranties.
