What is the nature of the armature reaction?
Introduction to armature reaction
An armature is a component of a motor that is equipped with wires. Because of the relative motion of the wires through the magnetic field between the pole pieces, causing the current induced in the wires (as in a generator) or causing magnetic induction due to current passing through the wires, it is here. Rotate in the magnetic field (as in the motor). Only the DC motor has an armature, the armature includes an armature core and an armature winding, and the armature winding is a circuit part of the DC motor, and is also a part that induces an electric potential and generates electromagnetic torque for electromechanical energy conversion (the generator is converted into mechanical energy) Electrical energy). The armature core is both a part of the main magnetic circuit and sometimes a support member of the armature winding, and the armature winding is embedded in the slot of the armature core. The AC motor is a rotor. The principle of the induced armature of the DC motor and the AC motor is roughly the same. The current in the armature winding of the DC motor is also AC, and the output through the commutator is DC. The AC motor is divided into an induction motor (asynchronous machine) and a synchronous motor. The induction motor is divided into a squirrel cage rotor and a wound rotor according to the rotor structure. The induction motor generates a magnetic field by the stator winding, and the rotor winding performs electromechanical energy conversion. The synchronous motor generates a magnetic field in the rotor winding, and the stator winding performs electromechanical energy conversion.
When no current flows through the armature winding, the magnetic field formed by the magnetic pole is called the main magnetic field and is approximately sinusoidally distributed. When there is current in the armature winding, the winding itself generates a magnetic field called the armature magnetic field. The effect of the armature magnetic field on the main magnetic field will cause the main magnetic field to be distorted and generate an armature reaction;
(1) Armature reaction at purely resistive load
The electromotive force of the armature magnetic field is the same as the current phase, and the armature magnetic field distorts the main magnetic field, and the half is strengthened and half is weakened;
(2) Armature reaction at purely inductive load
The current of the armature magnetic field lags behind the electromotive force by 90 degrees. The electromotive force generated by the armature magnetic field is opposite to the electromotive force generated by the main magnetic field, thus weakening the main magnetic field electromotive force, which is why the voltage drops when the three-phase circuit contains an inductive component; Longitudinal demagnetization armature reaction
(3) Armature reaction at pure capacitive loading
The current of the armature magnetic field leads the electromotive force by 90 degrees. Since the armature magnetic field is 90 degrees to the main magnetic field, the electromotive force generated by the armature magnetic field is the same as the electromotive force generated by the main magnetic field, thus strengthening the main magnetic field electromotive force, which is why the three-phase circuit The reason why the terminal voltage rises when the capacitive element is contained; this is called the vertical axis auxiliary magnetic armature reaction.
The nature of the armature reaction
The armature reaction is divided into the direct-axis armature reflection and the symmetrical load of the cross-axis armature reaction. The influence of the armature magnetomotive force on the fundamental wave of the main pole magnetic field is called the armature reaction. Its main properties are demagnetization and no effect (this is for the main flux)
