What is the difference between a DC motor and an AC motor?
Take a single-phase motor as an example. First of all, DC motors and AC motors are all kinds of motors, which are all operated by the action of a magnetic field. The DC motor can be regarded as a kind of stepper motor. So what is the difference in principle?
1, the motor structure is different
1) There is a coil inside the AC motor. This coil generally has a large resistance value, which is about 100 ohms. Take the phase shift as an example. It has a starting winding and a running winding.
2) The internal structure of the DC motor is mainly composed of the stator and the rotor. In the past, many of them were brushed motors. The rotor had a brush. There is also a Hall sensor on the motor to detect the position. During the working process, the conversion piece is continuously Alternate contact, thus forming an alternating magnetic field, constantly rotating, DC motor volume is generally smaller than AC, and now many companies use DC brushless motors.
2, the working principle is different
The AC motor supply voltage is AC, and the AC switch components can be used to control the motor on/off. For example, the thyristor must have sufficient withstand voltage when using the thyristor. For example, for the 220AV AC motor, the withstand voltage value of 400VAC or even 600VAC can be used.
For DC motors, its supply voltage is DC input, which can be controlled by PWM technology. PWM is a duty cycle adjustable signal that can be input differently. DC can be steplessly regulated, the speed series can be adjusted to a high level, and the feedback signal can be increased, the closed-loop speed regulation can be performed, and the braking function can be performed, that is, it can be stopped quickly and outputted in a certain period of time. The stability is better.
3, the output power is different
Generally, DC motors are smaller than AC motors, especially brushless motors, which overcome many shortcomings of brush motors, but they also have disadvantages such as resonance.
