Universal motor is a kind of motor in which the stator coil (namely excitation winding) and the rotor coil (namely armature winding) are connected to the power supply through the brush and commutator in series.
Single-phase Universal motor is commonly known as series motor or general purpose motor.Universal motor is a kind of motor in which the stator coil (namely excitation winding) and the rotor coil (namely armature winding) are connected to the power supply through the brush and commutator in series. Single-phase Universal motor is commonly known as series motor or general purpose motor.
Because the basic structure of the Universal motor is similar to that of the DC Universal motor, but it can be used for AC, so the principle of its rotation torque can also be expressed by the principle of the DC motor.
As shown in Figure 1, A constant current voltage is applied to the ends of the carbon brush A and B, and the current in the winding flows into the carbon brush A, flows through the conductor under the N pole through the conductor under the S pole, and then flows out of the carbon brush B. The winding moves because the magnetic field interacts with the magnetic field generated by the current in the conductor.
If the conductor is transferred to another polar magnetic field, the current direction in the winding will change accordingly through the action of the brush and commutator, that is, the current direction in the conductor under a certain polar magnetic field will remain unchanged, so that the force direction of the winding will remain unchanged. Therefore, the torque generated by the winding is always unidirectional.
Because Universal motor, in the case of AC power supply, stator current and rotor current will change at the same time, that is, stator flux and armature current will change at the same time, according to the left hand rule of motor, in the case of flux and armature current change direction, rotor steering will not change.
Although the polarity of the power supply changes repeatedly, the rotor always maintains a constant steering, which is the working principle of Universal motor.
Single-phase Universalmotor is mainly composed of stator, armature, bracket, brush holder and commutator.
Stator: The stator is the mechanical support of the whole motor, which is used to generate the main magnetic flux. It is mainly composed of the stator iron core and the excitation winding.
Armature: Armature, also known as rotor, is the rotation part of the motor, is the most important part of the motor. The role of the rotor is to generate electromagnetic torque, which converts electrical energy into mechanical energy. It consists of a rotating shaft, an iron core, armature winding, a commutator and a cooling fan.
Commutator: Commutator consists of many trapezoidal commutator pieces. Generally, mica sheet insulation is used between the reversing sheet and the reversing sheet, and glass fiber phenolic plastic is pressed in the half moon groove at both ends of the lower part of the reversing sheet, so that each reversing sheet can form a whole.
Carbon brush holder: Carbon brush holder is composed of chassis, brush grip, spring and carbon brush.
