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Motor Encyclopedia: The Difference between DC Motor and AC Motor
Release time:
2019-03-12 11:43
Source:
According to the type of power supply, motors can be divided into DC motors and AC motors. In this issue, Southern Anhui Motor will briefly introduce DC motors and AC motors and their differences.
DC motor is a kind of motor which can realize the mutual conversion between DC motor and mechanical energy, when mechanical energy is converted into electrical energy. The working principle of DC generator is to change the induction alternating electromotive force in armature coil from time-varying to direct current electromotive force by the commutator cooperating with the commutation action of brush.
Working Principle of DC Motor
A ring permanent magnet is fixed inside the DC motor, and the current generates ampere force through the coil on the rotor. When the coil on the rotor is parallel to the magnetic field, the direction of the magnetic field will change, so the brush at the end of the rotor contacts with the converter alternately, so the direction of the current on the coil will change, and the direction of the Loren magnetic force generated will not change, so the motor can keep one side. Turning.
The working principle of DC generator is to change the induction alternating electromotive force in armature coil from time-varying to direct current electromotive force by the commutator cooperating with the commutation action of brush.
The direction of the induced electromotive force is determined by the right hand rule (the magnetic induction line points to the palm, the thumb points to the direction of the conductor, and the other four fingers point to the direction of the induced electromotive force in the conductor).
The direction of force acting on the conductor is determined by the left-hand rule. This pair of electromagnetic forces forms a moment acting on the armature, which is called electromagnetic torque in the rotating motor. The direction of the torque is counterclockwise in an attempt to make the armature rotate counterclockwise. If the electromagnetic torque can overcome the resistance torques on the armature (such as those caused by friction and other load torques), the armature can rotate counter-clockwise.
Alternating current dynamo:
AC motor is a kind of machine used to realize the mutual conversion of mechanical energy and AC motor energy. Due to the tremendous development of AC power system, AC motor has become a common motor. Compared with DC motor, AC motor has no steering gear, so it is simple in structure, easy to manufacture and firm. It is easy to make high speed, high voltage, high current and large capacity motor. AC motor power covers a wide range, from several to hundreds of thousands of watts, or even millions of watts.
The difference between DC motor and AC motor:
1. The motor whose speed is proportional to voltage is a DC motor. The motor whose speed is proportional to frequency is called an AC motor.
2. DC motor is coil-by-coil commutation, while AC motor is phase-by-phase group commutation.
3. DC motor is voltage regulation and speed regulation, while AC motor is frequency conversion speed regulation, which is the watershed between DC motor and AC motor.
4. The fundamental difference between DC motor and AC motor is that the equation of potential balance is different.
1) The equation of potential balance of DC motor is U=C n.
2) The potential balance equation of AC motor is U=C F.
3) DC motor has fast response, large starting torque, and can provide torque from zero to rated speed. But the advantage of DC motor is just its disadvantage. For DC motor to produce constant torque under rated load, the armature magnetic field and rotor magnetic field must be maintained at 90 at the same time, it is caused by fire when the motor rotates by carbon brush and rectifier electrons. Flowers and carbon powders are not only harmful to components, but also limited in use. AC motors have no carbon brushes and rectifiers. They are maintenance-free, robust and widely used. However, complex control techniques are needed to achieve the performance equivalent to that of DC motors. Three-phase asynchronous motor has the advantages of simple structure, reliable operation and low cost.
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