完整版电机学英文文献翻译

The three-phase induction motor speed control method

Three-phase asynchronous motor speed formula: N = 60f / p (1-s) Can be seen from the above formula, change the power supply frequency f, motor pole number p and the slip s may be too much to change the speed of purpose. From the speed of the essence of view, is simply a different way to change speed synchronous AC motor does not change the sync transfer speed or two.

Widespread use in production machines without changing the synchronous speed of motor speed control method Wound Rotor Series Resistance Speed, chopper speed control, cascade control, and application of electromagnetic slip clutch, fluid couplings, clutches and other film speed. Change the synchronous speed of change on the number of stator pole multi-speed motor to change the stator voltage and frequency to frequency conversion with no change to the motor speed and so on.

Energy from the speed point of view when, with high speed method and inefficient methods of two kinds of speed: high speed when the slip refers to the same, so no slip losses, such as multi-speed motors, Slip frequency control and loss can speed recovery methods (such as cascade control, etc.). A deteriorating loss of speed control methods are inefficient speed, such as series resistance of the rotor speed method, the energy loss in the rotor circuit on; Electromagnetic Clutch The speed method, the energy loss in the clutch coils; fluid coupling speed, energy loss in the fluid coupling of the oil. General deterioration in loss increased with the expansion speed range, if not speed range, the energy loss is minimal.

1, variable speed control method of pole pairs

This speed is then used to change the stator winding way to change the red cage motor stator pole pairs to achieve speed control purposes, the following featuresWith hard mechanical

properties, good stability;

No slip loss, high efficiency; Wiring simple, easy to control, low price;

A level speed, differential large, can not get smooth speed control;

With pressure and speed adjustment, with the use of electromagnetic slip clutch, smooth and efficient access to high speed characteristics.

This method is suitable for the production does not require variable speed machinery, such as metal cutting machine Bed , Lift , Lifting equipment, Fans Water Pump And so on.

2, Frequency Control Method Frequency control is to change the motor stator Power supply Frequency, thus changing the speed of its synchronous speed method. Frequency control system main equipment is to provide variable frequency power supply Inverter , Inverter can be divided into AC - DC - AC inverter and AC - AC converter two categories, most of the current domestic use of AC - DC - AC inverter. Its characteristicsHigh

efficiency, speed the process without additional loss;

Wide range of applications, can be used for cage induction motor;

Speed range, features a hard, high accuracy;

Technical complexity, high cost, difficult maintenance and overhaul.