induction motor vs permanent magnet motor difference between permanent magnet synchronous motor and induction motor
At present, two major types of motors are widely promoted and adopted for new‑energy vehicles: permanent magnet synchronous motors and AC induction motors. Among them, permanent magnet synchronous motors are highly favored by domestic new‑energy automakers and have achieved extensive real‑world applications. By contrast, induction motors see far less adoption — not just among domestic users, but across global markets as well.
So why do permanent magnet synchronous motors gain such wide preference from new‑energy and traditional automotive manufacturers? What core distinctions exist between induction motor and permanent magnet motor? This article will tell you the answer.
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What Is the Difference Between Induction Motor and Permanent Magnet Motor?
1. Structural Differences
In terms of mechanical construction, permanent magnet synchronous motors feature more sophisticated structures and higher manufacturing costs. Nevertheless, they deliver the advantages of compact footprint and lighter weight.
A permanent magnet synchronous motor mainly consists of a stator, a rotor and end covers. Its stator shares strong similarities with that of a standard induction motor. The rotor, however, adopts a distinctive design fitted with high‑performance permanent‑magnet poles, which produce a rotating magnetic field once energized.
An induction motor also comprises a stator and a rotor, plus auxiliary components including end covers and cooling fans. Since its stator draws power from the grid to build the excitation rotating magnetic field, the stator acts as the armature for induction motors.
2. Differences in Working Principles
For permanent magnet synchronous motors, permanent magnets provide excitation to establish a synchronous rotating magnetic field. When armature reaction takes place between this rotating field and three‑phase stator windings, balanced three‑phase currents get induced, and rotor mechanical energy is converted into electric energy — the machine runs as a generator.
On the contrary, feeding balanced three‑phase alternating current into stator windings generates a spatial rotating magnetic field. Driven by electromagnetic force, the permanent‑magnet rotor follows this field and converts electric energy into mechanical rotor kinetic energy, so the unit works as a drive motor.
As for induction motors, symmetrical AC power supplied to three‑phase stator windings creates a rotating magnetic field that cuts across rotor windings. Induced currents are then generated within rotor conductors. Current‑carrying rotor conductors produce electromagnetic torque under the stator magnetic field, which turns the motor shaft and drives rotation following the direction of the rotating magnetic field.
To sum up: cutting magnetic flux lines will induce electric current inside conductors. The induced current interacts with magnetic fields and generates driving force to spin the rotor.
Raw‑material supply is another critical point of divergence. Permanent magnet synchronous motors rely on rare‑earth permanent‑magnet materials such as neodymium‑iron‑boron. Rare‑earth resources are scarce across Europe and North America. By comparison, China holds approximately 70% of global rare‑earth reserves and contributes 80% of worldwide total output.
