What are the differences between AC motors and DC motors?

Different Concepts:
1. An "AC motor" is a machine used to convert mechanical energy into alternating current (AC) electrical energy. Due to the rapid development of AC power systems, AC motors have become the most commonly used type of motor. Compared to DC motors, AC motors are simpler in structure, easier to manufacture, more robust, and easier to produce high-speed, high-voltage, high-current, and high-capacity motors because they do not have a commutator.

2. A DC motor is a rotating electric machine that can convert DC electrical energy into mechanical energy (DC motor) or mechanical energy into DC electrical energy (DC generator).

It is a motor that can convert DC electrical energy into mechanical energy. When it operates as a motor, it is a DC motor, converting electrical energy into mechanical energy; when it operates as a generator, it is a DC generator, converting mechanical energy into electrical energy.

Different Classifications:
1. AC Motors: AC motors are generally classified into several categories according to their function: AC generators, AC motors, and synchronous condensers. Due to the reversibility of motor operating states, the same motor can function as both a generator and a motor.

Classifications:Dividing motors into generators and motors isn't entirely accurate; some motors primarily function as generators, while others primarily function as motors.

2. A DC generator is a machine that converts mechanical energy into direct current (DC) electrical energy. It mainly serves as the excitation power source for DC motors, electrolysis, electroplating, electrometallurgy, charging, and AC generators. Although power rectifiers are used to convert AC to DC in applications requiring DC power, AC rectifiers cannot completely replace DC generators in certain performance aspects.

Different Principles

1. AC Motors Using a single-phase capacitor motor as an example: A single-phase motor has two windings: a starting winding and a running winding. These two windings are spatially 90 degrees apart. A large capacitor is connected in series with the starting winding. When single-phase AC current flows through both the starting and running windings, the capacitor causes the current in the starting winding to lead the current in the running winding by 90 degrees, reaching its maximum value first.

Two identical pulsed magnetic fields in time and space: These create a rotating magnetic field in the air gap between the stator and rotor. Under the influence of this rotating magnetic field, an induced current is generated in the rotor. The interaction between this current and the rotating magnetic field produces an electromagnetic torque, causing the motor to rotate.

2. DC Motor: A DC motor contains a fixed ring-shaped permanent magnet. Current flowing through the coils on the rotor generates an Ampere force. When the coils on the rotor are parallel to the magnetic field, the direction of the magnetic field changes with continued rotation. Therefore, the brushes at the rotor end alternately contact the transducer plates, causing the current direction in the coils to change as well. The Lorentz force remains constant, allowing the motor to maintain rotation in one direction.

The working principle of a DC generator is to convert the alternating electromotive force induced in the armature coils into a direct current electromotive force (DC) when drawn from the brushes, through the commutation action of the commutator and brushes.