Chenglin Gu

Influence of Skew and Cross-Coupling on Flux-Weakening Performance of Permanent-Magnet Brushless AC Machines

A method is proposed for predicting the flux-weakening performance of permanent-magnet (PM) brushless ac machines accounting for skew and d-q axis cross-coupling. The method is based on a d-q-axis flux-linkage model, a hybrid 2-D finite-element (FE)-analytical method being used to predict the d- and q-axis inductances. However, it only requires 2-D FE analysis of the magnetic field distribution over a cross section of the machine. The developed method is used to predict the torque-speed characteristic of an interior PM brushless ac machine with one stator slot-pitch skew. This is compared with predictions from a direct FE analysis of the machine and validated by measurements.

Magnetic field analysis and optimal design of DC permanent magnet coreless disc machine

The magnetic field in a DC permanent magnet coreless disc machine is studied in depth by using different methods, such as three dimensional finite element method (3DFEM), two dimensional finite element method (2DFEM) and magnetic circuit method (MCM) based on an analytical solution. For optimization, the cases for different magnet dimensions, airgap lengths and configurations are investigated in detail. Numerical results show that if the field is provided by the ferrite magnets, the ratio of magnet thickness to airgap length should be greater than 3 and the distance from magnet to stator wall or the width of the magnetism-free channels between two adjacent poles should be greater than 6 mm. Moreover, both 2DFEM and MCM are feasible for general optimal design purpose focusing on practicality and time saving. >

Anisotropic finite element computation of high density axially-laminated rotor reluctance machine

Nonlinear and anisotropic magnetic fields in a high density Axially-Laminated Anisotropic (ALA) rotor reluctance machine are computed by the finite element method. Different position angles between stator current vector and rotor d-axis (from 0/spl deg/ to 90/spl deg/), different pole span lengths (from 2/3 pitch to full pitch) and different applied currents (from 0 to 2 times the rated value) are investigated. Based on numerical results, the parameters and performance of this machine are calculated and discussed. Conclusions show that in order to achieve linear parameters and high performance, the per unit value of the magnetizing current should be less than 0.5 and the pole span length should be optimized. >

New approach to longitudinal magnetic field in drum type machine

Without 3D analysis, the longitudinal distribution of the magnetic field in a drum-type electric machine can be determined two-dimensionally, provided that radial results, fundamental components of the air gap flux density related to each axially-separated part, are obtained in advance by any conventional 2D numerical method. Details on the new approach, including how to bound the domain, how to represent the problem and how to solve it, are presented. As an application, a new type of synchronous machine with a two-part rotor, having a surface permanent magnet part and an axially-laminated anisotropic reluctance part axially-separated on the same shaft, is investigated, with obvious high computational economy and improved accuracy.

Simplified fuzzy logic based flux weakening speed control of IPMSM drive

This paper presents a simplified fuzzy logic based speed control scheme of an interior permanent synchronous motor (IPMSM). The proposed FLC is designed based on conventional max torque per ampere below the rated speed and flux weakening control above the rated speed. The simplified fuzzy logic controller is suitable for real time implementation because of the less computational burden. The application MATLAB Simulink was used for simulations of the FLC based IPMSM drive. The efficacy of the proposed simplified fuzzy logic controller base drive of the IPMSM with flux weakening is verified by the simulation.

Design and optimization of external-rotor torque motor

This paper introduces a permanent magnet synchronous torque motor with an external rotor, and provides the design and optimization of its electromagnetism and structure. Firstly, the basic structural features of this motor are described. In order to make the motor more compact and have higher power density, an improvement of cooling structure is made. Next, the method is determined and the program is compiled for electromagnetic computing, and the finite element analysis on magnetic circuits is conducted by applying ANSYS. Finally, by making the model and testing, the rationality of the design is verified.

There-dimensional temperature estimation of squirrel-cage induction motor using finite element method

This paper deals with 3-D temperature estimation for the squirrel-cage induction motor under rated load conditions, and it employs finite-element method to analyze the thermal fields. The 3-D temperature model (including stator and rotor) of the induction motor is established, and by analyzing the electromagnetic field of the induction motor, the loss distribution can be obtained, including rotor loss, iron loss, copper loss, and so on, which are taken as the heat source in thermal field analysis. The theoretical predictions are verified by direct comparison with experimental results.

Design and implementation of an electromagnetic clutch system for hub motors

Clutch is widely adopted in fuel vehicles, but it is rarely found in in-wheel motor driven electric vehicles. This paper proposes a general formula to solve the electromagnetic force and provides a clutch system for the newly designed bistable permanent magnet (PM) electromagnetic clutch in wheel hub motors based on the formula.

Magnetic field analysis and optimal design of a novel bistable permanent electromagnetic clutch

A novel bistable permanent electromagnetic clutch (BPMEC) unit is proposed which can be used in electric vehicles to fulfill flexible connect the motor and hubs. The magnetic field distribution of the clutch is predicted by using finite element method and magnetic circuit method. Subsequently, the main sizes are optimized by investigating flux leakage coefficient, and micro-topology of BPMEC is optimized by investigating magnetizing current.

Experimental research on the ALA+SPM hybrid rotor machine

The new type of ALA+SPM rotor synchronous machine is made of a surface permanent magnet (SPM) part and an axially-laminated anisotropic (ALA) reluctance part separately mounted on the same shaft. The displaced angle between the two parts d-axes has important influence on the motor performance, maximum load capacity of the hybrid rotor machines with different displaced angle was researched based on U/f = constant control in this paper, the results show that the hybrid rotor machine with reasonable displaced angle can obtain strong load capacity.