The difference between AC motors and DC motors is that they have different motor structures, different working principles, different output powers, different applications, and different characteristics.
1. Different motor structures
1) There is a coil inside the AC motor. The resistance of this coil is generally not very large, about a hundred ohms. Taking phase shifting as an example, it has a starting winding and a running winding.
2) The internal structure of a DC motor is mainly composed of a stator and a rotor. In the past, many brush motors had a brush on the rotor, and a Hall sensor on the motor to detect the position.
During the working process, it is constantly in alternating contact with the converter piece, thus forming an alternating magnetic field and constantly rotating. DC motors are generally smaller than AC ones. Now many companies use DC brushless motors.
2. Different working principles
1) The power supply voltage of an AC motor is alternating current. The motor can be controlled on and off through AC switching components, such as thyristors. When using thyristors, the withstand voltage must be sufficient. For example, for a 220AV AC motor, a withstand voltage of 400VAC or even 600VAC can be used.
2) For a DC motor, its power supply voltage is DC input, which can be controlled by PWM technology. PWM is a signal with an adjustable duty cycle and can be input with different values.
DC can carry out stepless speed regulation, the speed series can be adjusted to a very high level, and feedback signals can be added, closed-loop speed regulation, and braking functions can be performed, which means that it can stop quickly within a certain period of time and output The stability is relatively good.
3. Different output powers
Generally, DC motors have smaller power than AC motors, especially brushless motors, which overcome many shortcomings of brushed motors, but they also have their own shortcomings, such as resonance and other problems.
4. Different applications
DC motors are widely used in a variety of industrial and household devices such as fans, printers, power tools, and more. They have the characteristics of high efficiency, high torque, easy control of rotation speed, etc., so they are irreplaceable in many occasions.
AC motors are mainly used in household appliances, industrial equipment and other fields, such as electric fans, washing machines, compressors, etc. AC motors are widely used in household appliances due to their high efficiency and low noise.
5. Different characteristics
DC characteristics:
(1) Good speed regulation performance. The so-called "speed regulation performance" means that the motor can artificially change the speed of the motor as needed under certain load conditions. DC motors can achieve uniform and smooth stepless speed regulation under heavy load conditions, and have a wide speed regulation range.
(2) The starting torque is large. Speed adjustment can be achieved evenly and economically. Therefore, any machine that starts under heavy load or requires uniform speed adjustment.
Communication features:
AC motors have high working efficiency, no smoke, odor, no environmental pollution, and low noise. Due to its series of advantages, it is widely used in various aspects such as industrial and agricultural production, transportation, national defense, commercial and household appliances, and medical electrical equipment.