Study On Loss Model And Loss Reducing Measures Of Premium Asynchronous Motors

In the development of premium asynchronous motors, the key difficult problems in current stages are how to establish the loss computation model which can consider the multiple non-linear factors and the complex structural factors, then to study the relationship between motor losses and different factors and to discover the effective countermeasures for reducing the motor losses. This thesis systematically study the loss computation model and loss reducing measures of premium asynchronous motors with the method of the theoretical analysis, numerical computation and experimental study, the main works are as below.1. Currently, iron losses can only be roughly computed by means of empirical coefficients during the design of the series asynchronous motors. Aiming at this problem, an iron loss computation model with variable coefficients is presented, and then the new loss computation model based on Time Stepping Finite Element Method (T-S FEM) is established. On the basis of this model, the T-S FEM software are developed and used for the design of premium asynchronous motors in our country and the remarkable effect are reached.2. Aiming at the cage asynchronous motors, time variation waveform and loci of the flux density at different locations in stator and rotor core are studied. Then the main active area of rotational flux and its influence on local iron losses are discovered, and the distribution characteristics of loss density and loss distribution laws in different core areas are revealed.3. With the new loss computation model and theoretical analysis, the influence of structural factors, which are stator slot size, stator structural components of cramps slot, cramps and motor base, skewed rotors as well as cast aluminum and copper rotors, are systematically studied. And the relationship between the motor losses and structural factors, such as stator slot size, skewed rotors and so on, are revealed, which lays the theoretical foundation for further research on loss reducing measures of premium asynchronous motors.4. Taking a 5.5kW motor as an example, the new design scheme of motor structure are presented, in which some novel loss reducing measures are adopted in terms of stator slot size, stator structural components and rotor distribution manner. With those measures, the obvious decrease of motor losses is achieved, which provides the substantial technical support for the development of premium asynchronous motors.5. The experimental study on how to accurately test the asynchronous motor losses under low power factor are carried out. It is revealed that key influencing factors of different test methods, equipment and data processing method on accurate testing on motor losses, and the effective measures for accurate test on motor losses are obtained. A multi-functional prototype with new structure are designed and manufactured, which can be used to study the influence of different factors on motor losses.