Study On The Rotor Side Variable Frequency Adjustable Speed And The Energy Saving Technology Of Double-fed Motor

The motor are becomed the main energy provider for industrial and agricultural production and life,therefore,motors'energy saving are very significant for the response to the national call for energy saving.Double fed motor is the product of the combintion for motor,power electronics and NC technology,possessing AC induction motor and synchronous motor characteristics,having broad application prospects in the field of the speed and energy-saving control. This paper mainly discussed the double fed motor'energy saving control technology, the study content are as followed:At first,according to the basic control equation of the double fed motor, this paper analyzed the double fed motor's excitation voltage control characteristics,excitation frequency control characteristics and reactive power control characteristics;seted up tranducer's output frequency control model and output voltage conreol model,layed the theoretical foundation for the paper research.Then,this paper excogitated a new control method for double fed motor,basing on PLC and transducer. This new control method carried out the dynamic control of converter output characteristic by PLC.Thus,the transducer's output and output frequency can be adjusted separately;the function has been carried out that the transducer's output voltage is constant,the output frequency is continuously adjustable and the tranducer's output frequency is constant,the output voltage is continuously adjustable. The basic requirements for double fed motor's excitation control characteristic have been satisfied.This paper designed and carried out a new experimental control system for double fed motor,and this new system has been used as the reasearch platform for the double fed motor's energy saving control.The control system is mainly maked up by feeding control unit;control cabinet unit;system protection circuit unit.Finally,using this new experimental control system,double fed motor's three main experiments have been done successfully,including double-fed speed regulation experiment, power factor control experiment,reactive power control experiment.These experiments have proved control algorithm's correctness and feasibility.At the same time, These experiments also have proved hardware control system's stability and reliability.One national patent and one utility model patent have been applied by the key control technology.Theoretical analysis and experimental studies have shown that the control method is feasible and especially adapted to the loads like doubly-fed motors and other loads which need frequency conversion control or transformer control. Transmission and grid's efficiency can be improved. In conclusion, this technology has broad application prospects.