Abstract:The compound-structure permanent-magnet synchronous machine (CS-PMSM) is a power-split device which can enable the internal combustion engine (ICE) to operate at optimum efficiency during all driving conditions by controlling its torque and speed. However, the CS-PMSM has more serious temperature rise and heat dissipation problems than conventional permanent-magnet (PM) machines, especially when the CS-PMSM is running at low speed and under full load conditions. As the thermal resistance of double-layer air gaps is quite big, the hot spot proves to be in the inner winding rotor. To ensure the safe operation of the CS-PMSM, the use of forced-air and water cooling in the inner winding rotor are investigated. The study shows that the water cooling can provide a better cooling effect, but require a complicated mechanical structure. Considering the complexity of the high efficiency cooling system, a real-time temperature monitoring method is proposed and a temperature measuring system which can accurately measure the real-time temperature of multiple key points in the machine is developed to promptly adjust the operating and cooling conditions based on the measured temperature results. Finally, the temperature rise experiment of the CS-PMSM prototype is done and the simulation results are partly validated by the experimental data.

No abstract

No abstract

No abstract

The magnetic coupling problem is discussed for the six topologies of compound-structure permanent-magnet (PM) synchronous machine (CS-PMSM), and the radial-radial flux CS-PMSM is investigated as example. Taking Toyota Prius hybrid system as reference, a radial-radial flux CS-PMSM is designed. Owing to mechanical reason, the thicknesses of the PMs on the outer and inner sides of the outer rotor are quite different, which induces more coupling problem. The magnetic system of CS-PMSM is researched in two aspects: the combination of thicknesses of PM and outer rotor yoke and the effect due to armature reaction. It is concluded that the magnetic coupling problem can be solved by designing an appropriate outer rotor thickness. In order to evaluate the magnetic structure, a downsized radial-radial flux CS-PMSM prototype was designed and manufactured. Back electromotive force (BEMF), relations between torque and current, and efficiency of the prototype were measured, and the experimental results are in good accordance with the calculated results.Index Terms-Armature reaction, compound-structure permanent-magnet (PM) synchronous machine (CS-PMSM), dual mechanical port, hybrid electric vehicle (HEV), magnetic system.

Minimization of torque ripple in ferrite-assisted synchronous reluctance motors by using asymmetric stator AIP Advances 8, 056606 (2018) Due to the rising price of rare-earth materials, permanent-magnet (PM) machines in different applications have a trend of reducing the use of rare-earth materials. Since iron-core poles replace half of PM poles in the consequent pole (CP) rotor, the PM machine with CP rotor can be a promising candidate for less rare-earth PM machine. Additionally, the investigation of CP rotor in special electrical machines, like hybrid excitation permanent-magnet PM machine, bearingless motor, etc., has verified the application feasibility of CP rotor. Therefore, this paper focuses on design and performance of PM machines when traditional PM machine uses the CP rotor. In the CP rotor, all the PMs are of the same polarity and they are inserted into the rotor core. Since the fundamental PM flux density depends on the ratio of PM pole to iron-core pole, the combination rule between them is investigated by analytical and finite-element methods. On this basis, to comprehensively analyze and evaluate PM machine with CP rotor, four typical schemes, i.e., integerslot machines with CP rotor and surface-mounted PM (SPM) rotor, fractional-slot machines with CP rotor and SPM rotor, are designed to investigate the performance of PM machine with CP rotor, including electromagnetic performance, antidemagnetization capacity and cost. © 2017 Author (s)

A tubular flux-switching permanent-magnet linear machine (PMLM), which features unified magnetic field between the mover and two stators, is investigated for free-piston energy converter. The topology evolution, topology, operating principle and design considerations of the machine are thoroughly analysed. With the sinusoidal speed characteristic of free-piston Stirling engine considered, a tubular unified magnetic-field flux-switching PMLM is designed by finite-element analysis. Several main structural parameters, which include the outer and inner radius of the mover, the mover tooth width, the magnet thickness, the tooth widths of both the outer and inner stators and the widths of both the outer and inner stator yokes are studied to achieve high-force and mass-power density. Finally, the proposed machine is compared with two typical flux-switching PMLMs. The comparison results show that the unified magnetic-field flux-switching PMLM is suitable for applications which require highpower density, light mover structure and fast dynamic.

No abstract