1 Answer
The working principle of an induction motor is based on electromagnetic induction. It’s quite simple when you break it down. Here's how it works:
1. Stator Creates Rotating Magnetic Field
The stator of the motor is made up of coils connected to an alternating current (AC) supply. When AC flows through these coils, it generates a rotating magnetic field around the stator. This rotating field moves at a speed called the synchronous speed.
2. Induced Current in the Rotor
The rotor is the part of the motor that rotates. It’s typically a closed loop (like a cage in squirrel cage motors) and is placed inside the stator's rotating magnetic field. As the rotating magnetic field of the stator cuts through the rotor, electromagnetic induction occurs. This means that the changing magnetic field induces a current in the rotor, according to Faraday’s Law of Induction.
3. Force on the Rotor
According to Lorentz Force Law, the current in the rotor produces its own magnetic field, which interacts with the rotating magnetic field of the stator. This interaction creates a force on the rotor, causing it to start rotating. The rotor always tries to "chase" the rotating magnetic field, but it never quite catches up. This difference between the synchronous speed (the speed of the stator's magnetic field) and the actual speed of the rotor is called slip.
4. Continuous Rotation
The rotor keeps rotating because the stator’s magnetic field is continuously changing, and this keeps inducing currents in the rotor. As long as the AC power is supplied, this process continues, resulting in continuous motion of the rotor.
Key Points:
This principle of induction makes it simple, reliable, and low-maintenance for applications where constant speed and torque are needed.
1. Stator Creates Rotating Magnetic Field
The stator of the motor is made up of coils connected to an alternating current (AC) supply. When AC flows through these coils, it generates a rotating magnetic field around the stator. This rotating field moves at a speed called the synchronous speed.2. Induced Current in the Rotor
The rotor is the part of the motor that rotates. It’s typically a closed loop (like a cage in squirrel cage motors) and is placed inside the stator's rotating magnetic field. As the rotating magnetic field of the stator cuts through the rotor, electromagnetic induction occurs. This means that the changing magnetic field induces a current in the rotor, according to Faraday’s Law of Induction.3. Force on the Rotor
According to Lorentz Force Law, the current in the rotor produces its own magnetic field, which interacts with the rotating magnetic field of the stator. This interaction creates a force on the rotor, causing it to start rotating. The rotor always tries to "chase" the rotating magnetic field, but it never quite catches up. This difference between the synchronous speed (the speed of the stator's magnetic field) and the actual speed of the rotor is called slip.4. Continuous Rotation
The rotor keeps rotating because the stator’s magnetic field is continuously changing, and this keeps inducing currents in the rotor. As long as the AC power is supplied, this process continues, resulting in continuous motion of the rotor.Key Points:
- The motor doesn’t have brushes (like in a DC motor); the current in the rotor is induced by the magnetic field.
- The rotor always rotates at a speed slightly slower than the synchronous speed, which is what causes the induction and the torque that turns the rotor.
- The slip (difference between synchronous speed and rotor speed) is necessary for the motor to produce torque.
This principle of induction makes it simple, reliable, and low-maintenance for applications where constant speed and torque are needed.