This article Dalan Motor Xiaobian will introduce you to several commonly used speed control methods for motors.
This article Dalan Motor Xiaobian will introduce you to several commonly used speed control methods for motors.
1. Electromagnetic speed regulation motor speed regulation method
The electromagnetic speed regulating motor is composed of a cage motor, an electromagnetic slip clutch and a DC excitation power supply (controller). The DC excitation power supply is small, usually composed of a single-phase half-wave or full-wave thyristor rectifier. Changing the conduction angle of the thyristor can change the magnitude of the excitation current.
Speed ​​regulation characteristics of electromagnetic speed control motor:
1 speed regulation smooth, stepless speed regulation;
2 speed loss, low efficiency;
3 has no harmonic influence on the power grid;
4 The device structure and control circuit are simple, reliable in operation and convenient in maintenance.
The method is suitable for production machines with medium and small power, requiring flat sliding and short time and low speed operation.
2, stator voltage regulation method
Different speeds can be obtained when changing the stator voltage of the motor. Since the torque of the motor is proportional to the square of the voltage, the maximum torque drops a lot, and the speed adjustment range is small, making the general cage motor difficult to apply. A cage motor with a large rotor resistance value, such as a torque motor for voltage regulation and speed regulation, or a series frequency sensitive resistor on a wound motor, should be used. In order to expand the stable operating range, when the speed regulation is above 2:1, feedback control should be adopted to achieve the purpose of automatically adjusting the speed.
The main device for voltage regulation and speed regulation is a power supply that can provide voltage change. At present, the commonly used voltage regulation methods include series saturation reactor, autotransformer and thyristor voltage regulation. The thyristor voltage regulation method is optimal.
Characteristics of voltage regulation and speed regulation:
1 The voltage regulating speed regulation circuit is simple and easy to realize automatic control;
2 During the voltage regulation process, the slip power is consumed in the rotor resistance in the form of heat generation, and the efficiency is low.
The pressure regulation speed is generally applicable to production machines below 100KW.
3. Winding type motor rotor string resistance speed regulation method
The wound-type asynchronous motor rotor is inserted with an additional resistor to increase the slip of the motor and the motor operates at a lower speed. The greater the resistance in series, the lower the speed of the motor.
The method is simple in equipment and convenient in control, but the slip power is consumed in the form of heat on the resistor. It has a graded speed regulation and soft mechanical characteristics.
4, cascade speed control method
Cascade speed regulation refers to the addition of an adjustable additional potential in the rotor circuit of the wound-wire motor to change the slip rate of the motor to achieve the purpose of speed regulation. Cascade speed regulation can be divided into motor cascade speed regulation, mechanical cascade speed regulation and thyristor cascade speed regulation.
Generally, thyristor cascade speed regulation is adopted, and its characteristics are as follows:
1The capacity of the device is proportional to the speed regulation range, and the investment is saved. It is suitable for the production machinery with the speed regulation range of 70%-90% of the rated speed;
2 thyristor cascade speed power factor is low, harmonics have a greater impact;
3 can return the slip loss in the speed regulation process to the power grid or production machinery, and the efficiency is high;
4 When the speed control device is faulty, it can be switched to full speed operation to avoid production stoppage.
The method is suitable for use on fans, water pumps and rolling mills, mine hoists and extruders.
5, frequency control method
Frequency control is a speed control method that changes the frequency of the stator power of the motor and changes its synchronous speed.
The main equipment of the variable frequency speed control system is the inverter that provides the variable frequency power supply. The frequency converter can be divided into two categories: AC-DC-AC inverter and AC-AC inverter. At present, most of the domestic use AC-DC-AC inverter.
Its characteristics:
1 Wide range of applications, can be used for cage asynchronous motors;
2The technology is complex, the cost is high, and maintenance and repair are difficult;
3 high efficiency, no additional loss in the speed regulation process;
4 large speed range, hard features and high precision;
The method is suitable for occasions requiring high precision and good speed regulation performance.
----- Editor-in-Chief: Dalan Oil Pump Motor 02-Procurement Consultant
Copyright http: / (Dalan Motor) Reprint, please indicate the source
Http://news.chinawj.com.cn Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
Balcony Floor Drain,Balcony Square Drain,Balcony Floor Drain Strainer,Stainless Steel Balcony Floor Drain
Kaiping City Jinqiang Hardware Products Co.,Ltd , https://www.jqfloordrain.com