Loss Of Permanent Magnet Motor Research Articles

Improved energy saving control of IPMSM based on the weighted average current method

Aiming at the low efficiency of vector control system caused by unreasonable current allocation, an improved energy saving control strategy based on weighted average current method is proposed in this paper, and the research is carried out on the background of interior permanent magnet synchronous motor vector control system. This method does not add new parameters, but achieves the goal of reducing motor loss and improving current utilization rate. Firstly, according to the mathematical model of permanent magnet synchronous motor considering iron loss resistance, the relationship between motor torque and d-q axis current is deduced. Then, by introducing the weighted average current factor, the minimum copper loss current and the minimum iron loss current are calculated analytically. Finally, the simulation analysis shows that the energy saving strategy proposed in this paper can further reduce the electrical loss of permanent magnet motor compared with the traditional energy saving control method, which proves the feasibility of this method in improving the energy efficiency of the vector control system of permanent magnet motor.

Separation of Winding Losses of Permanent Magnet Motors by Considering Eddy Currents and Parallel Circuit Connections

In this article, we propose a method to separate the losses generated in armature windings of permanent magnet motors by using a combination of two different eddy current formulations and frozen permeability technique. The total Joule loss of the winding is separated into three components, which are produced by armature current from the terminal, eddy currents in each wire, and circulating currents between the wires. By using the proposed method, advantages and disadvantages of various kinds of winding configurations are investigated. The experimental verification of the calculated loss is also carried out.

Study of the Effect of Load Torque on the Iron Losses of Permanent Magnet Motors by using Finite Element Analysis

Study of the Effect of Load Torque on the Iron Losses of Permanent Magnet Motors by using Finite Element Analysis

2-D Exact Analytical Method for Steady-State Heat Transfer Prediction in Rotating Electrical Machines

Actually, the heat transfer prediction and temperature distribution in electrical machines are realized by using the finite-element method (Fem) and/or thermal equivalent circuit. The analytical resolution of partial differential equations representing the temperature distribution in electrical machines does not exist. In this paper, a 2-D exact analytical calculation of steady-state temperature distribution in rotating electrical machines by solving the heat equation in homogenous and nonhomogenous regions by using Fourier’s series and the separation of variables method is presented. It is based on the new subdomain technique where the solution depends on both directions ( $r$ , $\theta $ ) and able to model different materials of the machine with different thermal conductivities. The heat sources are volumique power losses due to hysteresis, eddy-current, and Joule losses in all the regions of machine. A simplified method is used to determine the power losses in permanent-magnet motors. The main studied problem is conductive with conductive interface conditions, although convective heat transfer in the air gap is also investigated. The boundary conditions considered for solving the conduction problem is a convective heat transfer between the machine and external air and at the rotor internal air. The semi-analytical results are in very good agreement with those obtained by Fem, considering both amplitude and waveform.

Effect of shrink fitting and cutting on iron loss of permanent magnet motor

Magnetic properties of a motor core are affected by the distortion due to the compression caused by shrink fitting and the distortion caused by punching, etc. In this paper, the B– H curve and iron loss of stator core of actual motor under shrink fitting are measured. It is shown that the maximum permeability is reduced by about 50%, and the iron loss is increased by about 30% due to the shrink fitting. It is illustrated that the loss of motor is increased by about 10%, 4% and 2% due to the shrink fitting, the cutting stress and the eddy current in rotor magnet, respectively.

Eddy current losses of permanent magnet motors

A simple and effective method for calculating the core eddy current losses in permanent magnet motors is presented. It uses the back EMF per tooth induced in the stator windings by the rotation of the permanent magnets. The eddy current losses of the stator yoke can also be evaluated as a function of the back EMF per tooth waveform. Simple expressions are obtained for motors with an even number of slots per pole pair. The experimental results refer to a permanent magnet motor with four poles and 36 slots. The proposed method is a general one, which does not depend on the number of motor slots or poles. It gives the possibility of using back EMF waveforms which are acquired experimentally or by numerical methods.

Core losses in permanent magnet motors

It is pointed out that the conventional approach to core loss prediction using the Fourier series of the space wave of air gap flux density is not applicable to surface mounted permanent magnet (PM) motors. An alternative approach based on the concept that eddy current losses are proportional to the square of the time rate of change of the flux density is presented. Expressions are derived for predicting hysteresis and eddy current losses in the stator teeth and yoke. Prediction of core losses is compared with measurement of losses on a four-pole PM motor, confirming the applicability of the proposed approach.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>