Flux PM Synchronous Machines Research Articles

Magnet Temperature Effects on the Useful Properties of Variable Flux PM Synchronous Machines and a Mitigating Method for Magnetization Changes

Variable flux permanent magnet synchronous machines (VF-PMSMs) use permanent magnet magnetization as an additional degree-of-freedom to reduce losses based on operating conditions (e.g., at medium to high speeds, losses are reduced by using a lower magnetization). Magnet properties are known to be dependent on temperature; therefore, the magnet temperature effects on magnetization manipulation and maximum torque properties in VF-PMSMs are investigated in this paper with FEA simulations and experiments. Increased magnet temperature changes the available range of attainable magnetization levels and makes demagnetization occur more easily; therefore, a different current angle and magnetization are needed for maximum torque operation. The temperature effects on high speed magnetization manipulation methods, which are needed for driving cycle loss reduction and full power capability, are evaluated with simulation and experiments on a prototype 80 kW traction machine. A closed loop method for magnetization manipulation that mitigates the effect of temperature is proposed.

Analysis of Magnetizing Trajectories for Variable Flux PM Synchronous Machines Considering Voltage, High-Speed Capability, Torque Ripple, and Time Duration

This paper discusses various transient trajectories for increasing the magnetization state (MS) of variable flux permanent magnet synchronous machines (PMSMs), a class of PMSM where the magnets are demagnetized and remagnetized using the drive inverter during drive cycle operation. To manipulate MS, a magnetizing current pulse can be used, which may drive a large amount of flux linkage in the machine. As a result, above low-speed operation, a large voltage may be required from the inverter. This paper extends several existing methods for improved voltage properties, and proposes and experimentally evaluates a new method—a straight line stationary frame flux linkage trajectory—for higher speed capability. The presented trajectories, along with existing trajectories, are organized into families and compared regarding their required voltage, high-speed capability, torque ripple, and time duration.

Design and control of a novel flywheel energy storage system assisted by hybrid mechanical-magnetic bearings

It is the intention of this paper to propose a compact flywheel energy storage system assisted by hybrid mechanical-magnetic bearings. Concepts of active magnetic bearings and axial flux PM synchronous machine are adopted in the design to facilitate the rotor–flywheel to spin and remain in magnetic levitation in the vertical orientation while the translations and rotations along and about x and y axes are constrained by mechanical bearings for simple operation. In this paper, the mathematical model of the flywheel’s levitation force and rotational torque is developed. The control systems of the position and velocity of the flywheel are designed based on PID method. Experiments are carried out and its test results prove the feasibility of the proposed flywheel system concept, the correctness of the mathematical analysis and the validity of the designed control system.

Dynamic vibration analysis of axial flux PM synchronous machines using coupled-field analysis

This paper presents the dynamic vibration analysis of axial-flux permanent magnet synchronous machines(AFPMSMs). The major sources of vibration in electric machines such as motors and generators are the magnetic force and mechanical geometric shape. To decrease the mechanical vibration in AFPMSMs, we proposed an advanced design method considering the coupled-field analysis of the electromagnetic and mechanical problems encountered for both the rotor and stator. By the proposed method, the AFPMSM was analyzed, and characteristics such as the magnetic force, natural frequencies, mode shapes, and deformation were studied. This study has accomplished the dynamic vibration analysis of AFPMSMs.