Research On The Loss And Temperature Rise Of High Speed Induction Motor

The high-speed induction motor has the advantages of simple structure and high mechanical strength.It doesn't exist the problem that the working point of the motor changes due to the demagnetization of the permanent magnet,which is w idely used in the compressor,vacuum pump,energy storage flywheel and automation industry.As the motor frequency is high,constrained by the frequency of power device and low carrier ratio,the motor voltage and current waveform will introduce harmonics associated with the carrier frequency.The motor magnetic field distribution is more complex and leads in the increase of electromagnetic loss.In this paper,we consider the high-speed induction motor as the research object,then establish the sinusoidal voltage drive and SPWM circuit drive loss calculation model,at last analysis the SPWM inverter circuit output characteristics and modulation parameters on the harmonic distribution.Based on the theory of convective heat transfer in three-dimensional temperature field,the model of motor temperature field is established.Finally,the experiment of high-speed induction motor loss and temperature rise is carried out.Firstly,the structural characteristics of high-speed induction motor and ordinary induction motor are compared.The size of the motor is calculated by using the magnetic circuit method and the finite element method.Then the six parameters of the T-shaped equivalent circuit are calculated by numerical analysis.The characteristics of the stator point of the magnetic density waveform is analyzed.The influence of rotor slot diameter,air gap length,stator tooth width and combination of rotor and stator slot numbers on the electromagnetic loss is analyzed.Secondly,the output harmonic characteristics of SPWM inverter circuit are analyzed,the carrier ratio and modulation ratio of the circuit is changed,and the variation law of harmonic distribution is analyzed.Using the Maxwell and Simplorer cosimulation method,the SPWM inverter model and the high-speed induction motor are connected,and the electromagnetic loss of the motor is calculated by harmonic analysis method for the case of low carrier wave.Then we change the carrier ratio and modulation ratio to study the trend of electromagnetic loss.Changing the carrier ratio is divided into two cases: whether to maintain the fundamental voltage equal.For the case where the carrier ratio is not an integer,the electromagnetic loss is calculated with the carrier frequency of 60 k Hz,and the method of suppressing the electromagnetic loss is obtained.Then,considering the influence of the speed of high-speed induction motor on the air conduction coefficient and the influence of the velocity of water in the water jacket on the stator surface,the coupling model of the motor fluid field and the temperature field is established by ANSYS.Various kinds of loss distribution and temperature rise in various parts of induction motor is obtained.Finally,the experimental study of high speed induction motor is carried out.The experimental system is used to measure the motor line voltage,phase current,input power and motor temperature.The wind friction loss of the motor is measured based on the free deceleration experiment,and the motor loss is separated and verify the correctness of the calculation model.