drive 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. A DC drive motor has a permanent magnet stator and a rotor that carries direct current. As we know from junior high school physics, a current-carrying conductor in a magnetic field experiences an Ampere force, causing the rotor to rotate. The advantages of this type of motor are its lower cost and lower requirements for the electronic control system. However, its disadvantages are its larger size and weaker power performance. DC motors are generally used in low-end pure electric mobility scooters.
2. Permanent magnet synchronous motors are actually DC motors, so their working principle is the same as that of DC motors. The difference is that DC motors use square wave current, while permanent magnet synchronous motors use sinusoidal wave current. The advantages of permanent magnet synchronous motors 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 motors are more complex in principle than the previous two, but can be roughly divided into three steps: First, alternating current is applied to the three-phase windings of the motor to generate a rotating magnetic field. Then, 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, induction motors are also called asynchronous motors.
The advantages of induction motors are low manufacturing cost and good power performance. The disadvantages are obvious to everyone: because they require alternating current, the requirements for the electronic control system are very high.
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.
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.
