Electromagnetic speed regulation of three-phase asynchronous motor

The electromagnetic speed regulating motor consists of a cage motor, an electromagnetic slip clutch, and a DC excitation power supply (controller). The DC excitation power supply has a small power and is usually composed of single-phase half wave or full wave thyristor rectifiers. Changing the conduction angle of the thyristor can alter the magnitude of the excitation current.
The electromagnetic differential clutch consists of three parts: armature, magnetic pole, and excitation winding. The armature and the latter have no mechanical connection and can rotate freely. The coaxial connection between the armature and the motor rotor is called the active part, which is driven by the motor; The coupling between the magnetic pole and the load shaft is called the driven part. When both the armature and the magnetic poles are stationary, if the excitation winding is energized with DC, several pairs of N and S polarity alternating magnetic poles will be formed along the circumferential surface of the air gap, and their magnetic flux will pass through the armature. When the armature rotates with the dragging motor, due to the relative motion between the armature and the magnetic poles, eddy currents are induced in the armature, which interact with the magnetic flux to generate torque, driving the rotor with magnetic poles to rotate in the same direction, but its speed is always lower than the speed N1 of the armature. This is a slip speed regulation method, and changing the DC excitation current of the slip clutch can change the output torque and speed of the clutch. The speed regulation characteristics of electromagnetic speed regulating motors:
·The device structure and control circuit are simple, reliable in operation, and easy to maintain;
1. Smooth and stepless speed regulation;
2. No harmonic impact on the power grid;
3. High speed loss and low efficiency.
This method is suitable for production machinery with medium to low power, requiring flat sliding and short-term low-speed operation.