Do you really know about variable pole dual speed motors?
In some special drag circuits, it is necessary to use a constant force motor with a dual speed motor; Sometimes it is even necessary to use a three speed or four speed electric motor. The principles and control methods of these multi speed motors are basically the same. Mainly used for various transmission machinery such as machine tools, mining, metallurgy, textiles, printing and dyeing, chemical industry, etc. that require step-by-step speed regulation of constant force motors according to the nature of the load. The requirement of achieving multiple speeds on the same motor is solved by different connections of the same winding and multiple sets of windings on the same motor.
Variable pole speed regulation is a method of changing the number of magnetic poles of an electric motor by altering the wiring of its stator winding, which allows for a step-by-step adjustment of the synchronous speed and achieves speed regulation of the motor. This type of speed regulating motor currently has a standardized series of products available for selection, such as single winding multi speed motors
Advantages: No additional slip loss, high efficiency; The control circuit is simple, easy to maintain, and has a low price; Cooperating with the electromagnetic differential clutch can achieve smooth speed regulation with high efficiency.
Disadvantage: It has a step speed regulation and cannot achieve stepless smooth speed regulation. And due to the limitations of motor structure and manufacturing process, only 2-3 pole pairs of graded speed regulation can usually be achieved, and the speed regulation range is quite limited.
There are many occasions in industry that require speed regulation, such as driving, fans, conveyor belts, machine tools, etc. Adopting pole changing speed regulation has the characteristics of low implementation cost, low power consumption, and good output torque rigidity. With the popularization of frequency converters, dual speed motors still have certain application space.
