The development of the robotics and the automation and the need for the motors that can work in the applications that require high speed, precision and increased efficiency have led to the increased use of permanent magnet synchronous motors and their continuous development in terms of improving their performance. Cogging torque is one of the features of these types of the motors that deteriorate motor performance especially at low speeds. Therefore, in this paper the method of genetic algorithms (GA) is applied as an optimization tool, for minimizing the cogging torque without changing the other important operating parameters like output power, torque or current. Even more, the optimized motor model has improved efficiency compared to the starting model and has the decreased weight of the permanent magnets. The optimization is done by changing the rotor design in terms of the magnet thickness, pole span and shape of the magnets. Finite elements (FE) models of the optimized and the basic motor were derived and from them the flux density distribution in the motor cross section and in the air gap was calculated. In addition, the improvement of the motor operation is observed from the torque characteristics calculated by the FE models.

Line-start synchronous permanent magnet motor (LSSPMM) is being considered as a replacement or alternative to asynchronous squirrel-cage motor (AM) in constant speed applications. This is due to the better efficiency and power factor than the asynchronous motor. There are various rotor topologies of LSSPMM concerning the magnets placement and their dimensions. The paper analyses six different rotor topologies in terms of achieving the best efficiency and power factor for the same output power of the motor with minimal consumption of permanent magnet material. All other motor design parameters remain unchanged, i.e. all motor topologies are analysed for the same stator laminations and the same motor windings. The numerical finite element method (FEM) models and dynamic models for obtaining transient characteristics of speed, torque and current verify the proposed design of various motor models. The results from all motor models are compared and adequate conclusions are derived regarding the optimal rotor topology in terms of obtaining the best efficiency and power factor with minimal consumption of permanent magnet material, for the same output power of the motor.

Line-start synchronous motors have attracted researchers’ interest as suitable replacements of asynchronous motors due to their high efficiency, which has been provoked by strict regulations regarding applicable efficiency classes of motors in the EU market. The research becomes even more challenging as it takes into consideration the diverse rotor topologies with different magnet locations for this type of motor. The rotor configuration with an interior asymmetric permanent magnet (PM) array rotor was chosen for analysis and optimization in this paper as this specific configuration is particularly challenging in terms of placing the magnets with adequate dimensions into the existing rotor of the asynchronous motor with a squirrel cage winding, in order simultaneously to obtain good operational characteristics such as high efficiency and power factor, good overloading capability and low material consumption. Therefore, an optometric analysis is performed in order to find the best configuration of the air gap length, magnet thickness, magnet width and number of conductors per slot, along with modifications of the rotor slot. The motor outer dimensions remained unchanged compared with the starting model of the line-start motor derived from the asynchronous motor, which is a product of the company Končar. The optimized model obtained higher efficiency, power factor and overloading capability than the starting model, along with good starting and synchronization capabilities.

Abstract

Paper proposes mathematical model of single phase shaded pole motor suitable for analysis of motor dynamic behavior. Derived mathematical model from d -q reference frame theory is applied at motor simulation model. Derived simulation model enables analysis of transient performance characteristics of motor currents, speed and electromagnetic torque under different operating regimes. Obtained results from the simulation are compared with data from analytical calculations based on method of symmetrical components and data from experiment for the purpose of verification of the simulation model. Simulation model is useful for studying the effect of parameters on motor starting and running characteristics at different types of loads.