The Research On The Energy-saving Protector Of Three-phase Asynchronous Motors

The research of energy-saving for three-phase Asynchronous Motors is always a hotspot in electric machinery area. Especially in recent years, the shortage of electric power supply in China makes it more urgent to research and popularize energy-saving devices for three-phase Asynchronous Motors. But at present, the cost of most energy-saving devices is too high. At a certain extent, this handicaps the popularize of energy-saving devices for three-phase Asynchronous Motors.This paper starts with the analysis of power loss of Asynchronous Motors, discusses the performance characteristics, energy-saving theory, energy-saving effects, anti-EMI of protectors and other problems that should be noticed when three-phase Asynchronous Motor switches from â–³ connection to Y connection. Based on these, a complete design of an energy-saving protector used for the Y/ â–³ transformation of three-phase asynchronous motor controlled by MCU is presented. To overcome the traditional shortcoming of frequent transferring in the Y/ â–³ transforming point, a method that adjusts the Y/ â–³ transforming point and the change time manually is presented.At last, a high performance-cost ratio energy-saving protector prototype has been made. After a successful experiment, more analysis and discussion have been done based on the result and some directionsand methods that will make the project more perfect are presented.