Differences and connections between DC motors and AC motors
Both DC motors and AC motors have a wide range of applications. The basic principles of both work are the same as the law of electromagnetic induction. Both have their own advantages and disadvantages. Analyze, DC motors or DC motors have commutators. This is also the main reason why DC motors and AC motors work differently.
Taking the motor as an example, if the motor wants to work, it must rely on the electromagnetic force induced by the rotor winding to drive the rotor to rotate. Therefore, in order to ensure the stable and continuous rotation of the motor, the induced electromagnetic force in the rotor winding must keep the same direction. For DC For the motor, the direction of the stator magnetic field does not change, so if the current in the rotor is not commutated, the direction of the electromagnetic force received by the rotor during the rotation will change, and the continuous rotation of the rotor cannot be guaranteed. That is, as long as the direction of the electromagnetic force in the rotor windings is consistent, the rotor can continue to rotate.
When the AC motor is working, this is guaranteed not by commutation, but by changing the direction of the stator magnetic field, because for the AC motor, the stator magnetic field is not fixed, but rotates according to a certain law, so it can be guaranteed The direction of the electromagnetic force on the rotor winding does not change. As long as the stator coils of the AC motor are arranged in phase, a rotating magnetic field will naturally be generated to ensure the rotor rotation.
The working principle of DC and AC motors is the law of electromagnetic induction, but there are also differences between the two, which can be understood through the different starting methods of the two. The rotation of the DC motor rotor (armature winding movement or force) is because the energized armature winding is subjected to electromagnetic force in the magnetic field, so the premise is that there is current in the armature, so the DC motor needs armature current to start; When the motor starts, as long as alternating current is applied to the stator, a rotating magnetic field will be generated. Since this magnetic field is moving, the rotor winding will induce an electromotive force. As long as the rotor winding can form a closed loop, a current will be generated, and an electromagnetic field will be induced. The force drags the rotor to rotate, so the premise of the rotor movement of the AC motor is that the magnetic field is rotating, which is the difference between the two in the initial state of movement.