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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.

Using chaotic anti-control technology to solve the unique noise generated by ocean reconnaissance robot was proposed in this paper in order to improve robot concealment. The mathematical model of ocean reconnaissance robot which thruster device is used as permanent magnet brushless DC motor was transformed in favor of chaotic anti-control study. On this basis, applied time-delay state variable feedback exact linearization method to chaotic thruster device. So the strange attractor of thruster device changed by changing the anti-control controller parameters according to actual situation. Finally, the anti-control controller was designed and verified by computer simulation. The simulation results show that the electromagnetic torque of thruster system can be chaotication under the condition of ocean reconnaissance robot normal running using time delayed state variable feedback exact linearization method. So the electromagnetic torque chaos lead to the shaft vibration changed, and the noise of propeller unique voiceprint characteristic is changed also. As a result, achieve the purpose of confusing the enemy.

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