Rafal Wrobel

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This paper presents a finite element investigation into the proximity losses in brushless AC permanent magnet motors used in hybrid/electric vehicle applications. The proximity effect in winding conductors is as a result of eddy-currents caused by magnetic fields generated by nearby conductors. This paper considers the influence of the conductor shape and(More)
This paper presents a thermal analysis of a segmented stator winding design. As the thermal performance is one of the main factors limiting a machine's output capability, a thermal test on a complete prototype machine is an essential part of the design process. However, for the segmented stator winding design, a test-informed thermal analysis on a single(More)
This paper investigates components of mechanical loss together with heat transfer effects in an axial-flux permanent-magnet motor. The mechanical loss components generated within electrical machines are well known; however, their prediction or derivation has not been widely reported in the literature. These, together with the electromagnetic loss sources(More)
It is common practice to represent a composite electrical winding as an equivalent lumped anisotropic material as this greatly simplifies a thermal model and reduces computation times. Existing techniques for estimating the bulk thermal properties of such composite materials use either analytical, numerical, or experimental approaches; however, these(More)
This paper presents a methodology for analyzing the thermal performance of compact planar wound components. A high-energy-density prebiased choke is used to demonstrate and validate the proposed approach. Loss predictions from electromagnetic finite-element analyses are coupled to an equivalent lumped-circuit thermal model and used to determine the(More)
Initial sizing of a brushless radial-flux permanent-magnet (PM) machine is typically based on assumptions regarding the electric and magnetic loadings together with the motor's active volume. Additional design assumptions include the winding current density and magnetic flux density within the core pack. These initial design decisions are crucial as they(More)
This paper evaluates a three-phase ac main exciter (ME) for a wound-field synchronous aircraft starter-generator capable of operating in both starting and generating modes. The research has been based around a 225-kVA generator utilizing the existing single-phase ME hardware. Initially, a reconfiguration of the existing single-phase unit into a three-phase(More)