Research On The Three Wave Starting Asynchronous Motor

After many years of development,AC asynchronous motor has developed into a motor type characteristic of full range,diverse features and the most extensive application scope.Along with social progress and technological development,AC electric drive system requires modern asynchronous motor to have new advantages such as high power density,high efficiency,high starting performance,and wide speed range.The traditional three-phase cage type asynchronous motor is of simple structure,poor starting performance,so it is not suitable for the occasions of high load or full load;although three-phase wound asynchronous motor is of better starting performance,it is not inconvenient to use and maintain due to the complex structure with slip ring and brush,and is suitable for explosion-proof,inflammable and dangerous situations.In view of the shortcomings of present three-phase asynchronous motor of too large starting current and small starting torque during direct starting,in the paper,the three wave asynchronous motor with high starting performance is studied by using three wave start principle.The current frequently-used starting methods of three-phase asynchronous motor are first introduced;their advantages and disadvantages are pointed out and the research purpose of the paper is put forward.In Chapter 2,the basic principles of three wave starting are introduced in details and the design methods and requirements of the type of motor are explained.In Chapter 3,the methods of the modern winding theory is used and three sets of stator three-phase winding schemes that can produce fundamental wave magnetic potential and main and sub-harmonic magnetic potential are designed;and the harmonic contents of the three groups schemes are analyzed by harmonic analysis program;a set of optimal solution is determined.In the Chapter 4,according to the design requirements of the three waves start rotor winding,winding connection scheme that can provide the fundamental wave induced current and harmonic induced current with rotors of different flow paths are designed;the rotor winding schemes are analyzed in details by using the vector diagram.In the Chapter 5,in order to make the analysis of three wave starting asynchronous motor performance easier,on the basis of the equivalent circuit of the starting condition,the motor parameter calculations at starting conditions are studied,and the similar characteristics at running state to the traditional induction motor are combined;the complete electromagnetic computing scheme is obtained.In the Chapter 6,the designed stator scheme and rotor winding scheme are applied in traditional three-phase asynchronous motor;a prototype is created with the basic structure sizes of the motor unchanged;and the experiment is carried on the prototype;the test data are compared with the data of traditional motor,fully showing the advantages of three wave starting asynchronous motor starting performance.The new energy.saving asynchronous motor studied in the paper has a large starting torque,small starting current,excellent operating performance,simple rotor structure,high reliability and other advantages,so it can be widely used in occasions that require good starting performance and do not require additional equipment;at the same time,it can also avoid the energy waste that often appears in previous electric drive system,which saves energy and reduces the cost of investment and can be conveniently popularized.