What are the differences between continuously variable and step variable speed motors in terms of structure and performance comparison?

Speed regulation is a practical requirement for many working conditions or equipment. Currently, there are mainly two types of motor speed regulation methods: one is variable pole speed regulation, which is represented by multi speed motors and has a step by step speed regulation, and the other is represented by variable frequency motors and permanent magnet synchronous motors and has a stepless speed regulation.

A continuously variable speed motor is a variable frequency motor powered by a frequency converter. During the entire speed regulation process, the connection of the motor body will not change. The output of the motor is adjusted as a whole by changing the voltage and frequency output of the frequency converter. Generally, in the range of starting and frequency lower than the fundamental frequency, the motor operates in a constant torque manner. When the frequency output of the frequency converter is higher than the fundamental frequency, the motor operates in a constant power manner, which can ensure that the motor does not suffer from adverse consequences caused by overload in all frequency ranges.

Most variable pole speed motors are used according to the power frequency, and the motor speed can be divided into several different gears according to specific needs, such as two speed, three speed, and four speed. During the operation of the motor, the actual output power and speed can be changed by changing the motor connection.

For this reason, the stator part of this type of motor is undergoing changes. Some multi speed motors have a set of windings that can be converted through different wiring methods for the same winding, while others may require two sets of windings to achieve this. Therefore, the number of lead wires for multi speed motors will be increased, and the conversion during operation will be solved through control switches.

The characteristic of a variable pole motor may be that it performs best at a certain speed state, while there may be some poor performance in other speed states. Therefore, the possibility of achieving optimal performance at all speeds in the same motor is relatively small.

Whether it is a variable pole speed regulating motor or a polar speed regulating motor, temperature rise control should be based on the actual operating characteristics of the motor, and a comprehensive selection of temperature rise level control that meets its full cycle operation should be made. The starting performance of a stepped speed regulating motor should be set according to the actual operating characteristics