Lu Yongping

Theoretical and Simulation Analysis of Influences of Stator Tooth Width on Cogging Torque of BLDC Motors

Cogging torque reduction is one of the most important requirements in the design of BLDC motors due to its direct impact on the performance of the motor. In this paper, the influences of tooth width and slot/pole match on cogging torque corresponding to both uniformed teeth and nonuniformed teeth were theoretically analyzed on the basis of analytical expressions of cogging torque deduced with energy method. Furthermore, several models which denote features of different slots and poles were setup and calculated in finite element analysis software Flux2D, the result of which verified the theoretical analysis. Valuable conclusions and some suggestions were given in the paper which is meaningful to the design of good performance BLDC motors.

Numerical calculations for ferrofluid seals

The magnetic field and the seal capacity of ferrofluid seals are calculated and analyzed by numerical methods. Based on the magnetic filed calculations, the isobars in the ferrofluid and the cross sections of the fluid sealing ring are described. The relations of the seal capacity to the ferrofluid amount and the magnetic circuit parameters are analyzed. The action of the centrifugal force on the seal is indicated. >

Solutions of three-dimensional multiply connected and open boundary problems by BEM in three-phase combination transformers

A boundary element method (BEM) in terms of magnetic vector potential and electric scalar potential is successfully applied to three-dimensional, multiply connected, and open boundary problems caused by the heavy current of leads in a three-phase combination transformer. The quasi-frontal method is employed for the solution of the set of equations with asymmetric and full coefficient matrix. At most a quarter of the whole matrix needs to be stored. The numerical results are compared with experimental values and show very good agreement. Corrective measures for reducing the losses and preventing the box from locally overheating are presented. >

Error analysis and compensation of multipole resolvers

The signal errors of the multipole resolver and the measurement error incurred due to the signal errors are analysed, and expressions for the errors are determined. Based on the results of the analysis, a compensation method utilizing an analogue circuit for the measurement error is presented. The zero-position error and the amplitude error of the 34-pole resolver are compensated using the compensation circuit presented. The measurement accuracy of the 34-pole resolver is improved significantly from about 15 to 2 min. The correctness of the analysis result and the effectiveness of the compensation method are also verified.

Structure optimization for brushless DC motor in robot's arms using FEM

Along with the progress of intelligent control and robot technology, machine arms, which are not so easy to be effected by the environment, easy operated, have taken place of human in more and more field. The motor used in the joint of machine arm is very important and has more influence on the system. The choice of the motor and relative method of control has more or less effect on the cost, operating precision and the reliable of the arm. Among all the motors that can be used in the joints, brushless DC motor (BLDCM), which has advantages as low cost, light quality and high reliable etc., has taken more and more attentions. In this paper, we analyze the characters of one kind of the high-energy density designed BLDCM in robot according to environment and its structures.

A simplified testing method of copper loss and its temperature raise for multiunit propulsion permanent magnet synchronous motors

Large power low speed Permanent Magnet Synchronous motors are more and more widely used in propulsion areas. Their tests are relatively more inconvenient because some special and large power equipments are needed. In this paper, according to the features of multiphase and multiunit for these kinds of motors, a novel and simplified testing method of copper loss and its temperature raise is brought out. With a special control tactics, the needed characteristics were obtained without any additional equipment. The method is proved to be more practical in engineering testing.

Analysis of radial electromagnetic force under different poles/slots matched in large torque PMSMs

Vibration and noise reduction is one of the most important requirements in the design of PMSM due to its direct impact on service life and operating stability. The radial electromagnetic force acted on the rotor is a major factor of a PMSM influencing on its vibration and noise. In this paper, the distribution characteristics of radial electromagnetic force were theoretically analyzed on the basis of FEM method in Ansoft, simulation analysis of radial electromagnetic force corresponding to different slot/pole structures was carried out, and test of direct-driven large torque PMSMs was presented to validate the theoretical analysis. The conclusion has a good meaning to optimum design of these motors.

The mathematical model and field-oriented control for 15-phase brushless direct current motor with an opened phase

The paper presents a transformation matrix and a mathematical model for 15-phase brushless direct current (BLDC) motor with an opened phase. With the mathematical model, the field-oriented control can be put into use for the BLDC motor. According to the model, a fault-tolerant control system is proposed to guarantee the high-performance of 15-phase BLDC motor subject to the loss of one of a stator phase opened circuit. Simulation result reveals that the fault-tolerant system can meet the demand of disturbance-free operation when the open-circuit fault occurs in stator windings.

Tooth-slot cogging torque and noise analysis of permanent magnet motors

Cogging torque is one of the sources which cause noise in a permanent magnet (PM) motor system. Conditions of producing a cogging torque are discussed in the paper and experiments were carried out on several samples, which proved that the analysis is correct in theory, and meaningful in practice.

Application of modified FBT algorithm in induction motor series optimal design

Some improvements are made for Fast Boundary Tracking algorithm according to the practice of the electric machine design in the paper. As discrete variables play a dominant role in determining the values of the objective function and the constraint functions in the motor optimal design, the algorithm is improved in the paper. From the algorithm, a software is developed and used for the optimal design of the induction motors of Y series. The results show that the algorithm is reliable and efficient.