Permanent magnet motor is a kind of efficient energy-saving motor. It refers to the DC motor whose stator is permanent magnet only rotor is coil. The stator of ordinary motor is coil.
Permanent magnet motor manufacturers have a wide variety of permanent magnet motors, different structures, different occasions of use. Because of the less controllable means the non adjustable excitation, different types of permanent magnet motors show different characteristics under different operating conditions.
We know that the more stable the operation of the permanent magnet motor, the higher the efficiency, but there will be voltage instability in the use of the permanent magnet motor. If it is treated, it will cause the motor to burn out. The permanent magnet motor manufacturers usually adopt three methods to deal with this problem:
1. Field regulation in the excitation circuit: a suitable resistive load such as incandescent bulb is paralleled at both ends of the resistance of the permanent magnet DC motor. The resistance value of the resistive load after heating is changed to a non-linear resistance characteristic, so that the field resistance line has a larger intersection angle with the starting section of the excitation characteristic, an obvious intersection point with the no-load characteristic curve is obtained, so that the permanent magnet DC motor also has a lower voltage There will be stable work points.
2. Magnetic grade gasket: a benign magnetic conducting material is padded under the magnetic grade shoe to reduce the gap of excitation magnetic field, which can make its output characteristic saturated when the excitation current is small, so as to make its output voltage stable.
3. Automatic excitation regulating device of generator: the automatic excitation regulating device of generator has good excitation characteristics, constant reactive power, constant power factor other regulating methods, which is very effective to improve the stability transient response ability of the system, can solve the problem of generator reactive power swing caused by unstable output voltage system voltage fluctuation.