Jianhui Hu

Optimization of split ratio to design the PM brushless DC motor

The split ratio of the permanent magnet motor is one of the most important design parameters. It can not only influence the motor electrical torque and efficiency, but also can influence the motor thermal behavior. According to the high torque, short duty permanent magnet brushless motor, the thermal behavior should be investigated carefully. In this paper, the influence of the split ratio on the motor characteristics is investigated by field and circuit coupling finite elements analysis firstly. Then the influence of the split ratio on the motor thermal behavior of is analyzed, emphasis on the high torque short duty operation. The optimal design results are verified experimentally.

Design Considerations of Tubular Transverse Flux Linear Machines for Electromagnetic Launch Applications

Due to the achievable high force densities, permanent magnet linear machines with transverse flux configurations are gaining increased interest in electromagnetic launch (EML) applications, in which the force density demand is crucial. This paper deals with the design of a tubular transverse flux linear machine (TFLM) targeting EML applications, and the issues pertinent to its topology selection, design optimization, and thermal modeling are discussed. By overall comparison of practical topologies and technologies of the TFLM, a tubular moving-magnet topology with separated flux paths is believed to be more appropriate. Design optimization is then performed to maximize the thrust force under specific volumetric constraints. It is shown that the thrust force is more sensitive to the stator segment length, instead of the magnet thickness. Regarding the overload requirement inherent in EML systems, special focus is given on the thermal characteristics of the TFLM at overload conditions, and it is proved that the machine shows appreciable overload capability. Measurements carried out on a prototype TFLM have validated the predictions.

Design of a novel flywheel reaction torque measurement system based on disturbance observer

A novel flywheel reaction torque measurement system is proposed to measure the output torque of flywheels. The system structure and principle of the measurement system are presented. Finite-element method is applied to compute the magnetic field and characteristics of the measurement system. An improved disturbance observer is applied in the position closed loop control system. Simulation and experiment show that the system dynamic characteristics can be improved by the disturbance observer.