From the output characteristics, the speed-adjustable motor can be divided into two categories: stepless speed regulation and stepped speed regulation. When it comes to specific speed regulation methods, there are many kinds of it. Professionals can hardly explain it in a short time. Dalan Motor Editor feels it necessary to sort it out.
1. Electromagnetic speed regulating motor
It is composed of single-speed or multi-speed squirrel-cage asynchronous motor and electromagnetic slip clutch. It is also often called slip motor, which is a constant torque AC stepless variable speed motor. It is widely used in printing presses and staplers, wireless binding, high-frequency drying interlocking machines, and chain boiler grate control.
Advantages: simple structure, small control device capacity, and cheap value. Reliable operation and easy maintenance. No harmonic interference.
Disadvantages: large speed loss. Because the slip of the electromagnetic slip clutch is large, the maximum speed of the output shaft is only 80% to 90% of the synchronous transfer of the motor; the slip power is completely converted into the loss of heat in the process of speed regulation, the efficiency is low, and the problem of heat generation is serious.
2. Frequency conversion motor
Frequency conversion motor is a general term for motor driven by frequency converter. Frequency conversion motor is abbreviated as frequency conversion motor, which is the general name of the motor driven by frequency converter. In fact, the motor designed for the inverter is a special motor for frequency conversion. The motor can achieve different speeds and torques under the drive of the inverter to adapt to changes in load demand.
Advantages: no additional slip loss, high efficiency, wide speed range; for occasions with low load operation time or frequent start-stop operation, it can achieve the purpose of power saving and motor protection.
Disadvantages: The technology is more complicated and the price is higher.
3. Pole-changing multi-speed motor
In some special drag circuits, two-speed motors are needed; sometimes three-speed or four-speed motors are even needed. The principles and control methods of these multi-speed motors are basically the same. It is mainly used in various transmission machinery requiring step-by-step speed regulation with the nature of the load, such as machine tools, mining, metallurgy, textile, printing and dyeing, chemical industry and other industries. The requirement of multiple speeds for the same motor is solved by different connections of the same winding and multiple windings of the same motor.
Advantages: no additional slip loss, high efficiency; simple control circuit, easy maintenance, and low price; cooperate with electromagnetic slip clutch to obtain smooth speed regulation with high efficiency.
Disadvantages: stepped speed regulation, can not achieve stepless smooth speed regulation. Moreover, due to the limitation of the structure of the motor and the manufacturing process, usually only 2 to 3 kinds of pole-pair stepped speed regulation can be realized, and the speed regulation range is quite limited.
4. The DC motor adjusts the armature voltage and adjusts the excitation and speed
The DC motor is a stepless speed regulating motor with excellent speed regulation performance, but the maximum limit of its running speed is greatly restricted due to the existence of the inverter.
Advantages: The speed control performance is very good, the speed control methods are diversified, and the operation efficiency is high.
Disadvantages: can not be used for high-speed operation, must be equipped with carbon brushes and commutator.
5. Permanent magnet synchronous motor and permanent magnet brushless motor
Both permanent magnet synchronous motors and permanent magnet brushless motors achieve stepless speed regulation through PWM frequency conversion speed regulation devices. The maximum speed is theoretically unlimited, and the efficiency is high, and the power factor can be controlled around.
Advantages: stepless speed regulation, in theory, there is no limit to the speed regulation range.
Disadvantages: Magnets are expensive and have the problem of demagnetization.
----- Responsible Editor: Dalan Oil Pump Motor 02-Procurement Consultant
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