Take a single-phase motor as an example. First of all, DC motors and AC motors are both types of motors. DC can be seen as a type of stepper motor. So what's the difference in principle?
1.The motor structure is different
1) There is a coil inside the AC motor. The resistance of this coil is generally not very large, which is about 100 ohms. Taking phase shift as an example, it has a start winding and a running winding.
2) The internal structure of a DC motor is mainly composed of a stator and a rotor. Many of them were brush motors in the past. The rotor has a brush. The motor also has a Hall sensor on it, which detects the position. The alternating contact of this way forms an alternating magnetic field and keeps rotating. DC motors are generally smaller in size than AC. Many companies now use DC brushless motors.
2. Works differently
1) The power supply voltage of the AC motor is AC. You can control the on and off of the motor through AC switching components, such as thyristors. When using thyristors, the withstand voltage must be sufficient. For example, for 220AV AC motors, the withstand voltage can be 400VAC or even 600VAC.
2) For DC motor, its power supply voltage is DC input, which can be controlled by PWM technology. PWM is a signal with adjustable duty cycle, which can be input differently. The following figure shows the output of a brushless DC motor. One of the upper and lower arms is turned on, and the motor output is 310V. DC can perform stepless speed regulation, the speed series can be adjusted to a high level, and feedback signals can be added, closed-loop speed regulation, and the brake function can be performed, that is, it can be stopped quickly within a certain period of time, and the output The stability is better.
3.Different output power
Generally, DC motors have less power than AC motors, especially brushless motors, which overcome many of the disadvantages of brushed motors, but they also have disadvantages such as resonance and other problems.
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