Induced eddy currents in can cause loss when the canned motor runs, the loss make the motor`s temperature rise, directly affect the canned motor pump and the entire transmission system security. Empirical formula estimates eddy current losses which has a big error, it is difficult to meet the engineering requirements. For the canned motor with Hastelloy-C alloy or Sus316L cans, analyzed electromagnetic field and calculated can loss using a finite element method of Ansoft. The paper developed four prototypes, and obtained the experimental value of can loss via simple no-load experiment by the loss separation method. The results are compared with simulation value show that the accuracy of FEM is higher accurately than empirical formula; Analysis shows that dimension of a model and can material characteristic parameters such as the resistivity influence on the calculated error of FEM, the paper proposes to correct the error in the case of considering can material characteristic parameters.

Cogging torque is one of the most important parameters of permanent magnet motors, which causes torque ripple, vibration and noise. This paper describes the mechanism of cogging torque, introduces several methods of reducing cogging torque and points out the advantage of novel magnet arrayed permanent magnet motor in reducing cogging torque. Ansoft software is used to build the simulation of conventional surface-type permanent magnet motor and novel magnet arrayed permanent magnet motor and to calculate their cogging torque. a cogging torque testing system which included the angle sensor, permanent magnet motor, torque wrenches and other components are tested two different structures motors’ cogging torque .The experimental result is consistent with the simulation results, it shows that the method of novel magnet arrayed permanent magnet motor reducing cogging torque is correct. The new method compare with the same specification on the surface of permanent magnet motor can reduce more cogging torque.

In order to improve the sinusoidal level of air gap magnetic field of the traditional surface PMSM, reduce its harmonic losses and fully reflect its energy-saving advantages, this paper introduces a type of sinusoidal pole width modulation permanent magnet synchronous motor. The surface magnetic poles of the rotor iron core constitute by a number of small array magnets, which makes the air gap magnetic field more sinusoidal. Placing starting winding in remaining space between array magnets of rotor outer surface to make surface-mounted permanent magnet synchronous motor add self-starting function. The sine wave distortion rate of air gap magnetic field of sinusoidal pole width modulation structure was compared with traditional surface-mounted structure by electromagnetic field calculation and experiment. The copper starting winding and aluminum starting winding were placed in sinusoidal pole width modulation structure motor respectively, and then the paper analyzes dynamic torque and rotational speed of self-starting progress. Finally the analysis is verified by experiments.

Cogging torque is one of the most important parameters of permanent magnet motors, which causes torque ripple, vibration and noise. This paper describes the mechanism of cogging torque, introduces several methods of reducing cogging torque and points out the advantage of novel magnet arrayed permanent magnet motor in reducing cogging torque. Ansoft software is used to build the simulation of conventional surface-type permanent magnet motor and novel magnet arrayed permanent magnet motor and to calculate their cogging torque. a cogging torque testing system which included the angle sensor, permanent magnet motor, torque wrenches and other components are tested two different structures motors’ cogging torque .The experimental result is consistent with the simulation results, it shows that the method of novel magnet arrayed permanent magnet motor reducing cogging torque is correct. The new method compare with the same specification on the surface of permanent magnet motor can reduce more cogging torque.

The voltage harmonic is an important indicator to evaluate the power quality of PM wind generator. Voltage waveform is closely related to the degree of the air-gap magnetic field waveforms sinusoidal in the motor, so generator structure optimization to improve the degree of air-gap magnetic field sinusoidal is an effective method to improve the quality of generator voltage waveform. This paper presents a method called pole width modulation method to reduce voltage harmonic of wind permanent magnet generator. Do respectively finite element analysis to traditional surface permanent magnet generator and a new very wide modulation permanent-magnet generator; and then develop two structure prototypes and build voltage waveform experimental equipment to study them. Finite element analysis and prototype experiments show that the pole width modulation method is one of the effective and feasible technologies on reducing the voltage harmonic of PM Wind Generator.