Thermal analysis of a winding turn-to-turn fault in PM synchronous machine

This paper presents a detailed lumped parameter (LP) thermal model of an armature slot in a permanent magnet synchronous machine for traction applications. The model is used to investigate the temperature distribution in the slot after a turn-to-turn failure occurs. Steady-state analyses are conducted and a good agreement is found with FEM thermal simulations. The LP model is modified into a transient model and transient thermal analysis are conducted to predict the processing damage in the slot, which eventually might lead to a turn-to-tooth (ground) failure

Comparison of winding topologies in a pot core rotating transformer

This paper discusses the comparison of two winding topologies in a contactless energy transfer system from the stationary to the rotating part of a device. A rotating transformer, based on a pot core geometry, is proposed as a replacement for wires and slip rings. An electromagnetic and a thermal model of the rotating transformer are derived. The models are combined and used in a multi-objective optimization. A Pareto front, in terms of minimal volume and power losses, is derived to compare both winding topologies. Finally, the optimization algorithm is used to design a prototype transformer for each winding topology, which are manufactured using a commercially available pot core

Inductance calculation nearby conducting material

This paper presents the modeling of inductances nearby conducting material. A 3-D magnetic model is derived based on Fourier analysis in which the diffusion equation is incorporated. The model is applied to calculate the mutual inductance in a contactless energy transfer system between four primary coils and a single secondary coil for different positions of the secondary coil. The calculated values are compared with finite element simulations and measurements. A difference of maximum 7% is obtained among the different methods

Contactless power transfer to a rotating disk

This paper discusses a power transfer system from the stationary to the rotating part of a device, by means of contactless energy transfer. A rotating transformer is proposed as a replacement for wires and slip rings. A pot core geometry is used for the rotating transformer and two different winding topologies are compared. The transformer is analyzed in the electromagnetic and thermal domain. An analytic model for each domain is derived. The validity of the analytical models is confirmed with both 2D and 3D FEM simulations and measurements. Two prototype rotating transformers are designed for the transfer of 1 kW peak, rotating at 6000 rpm. The prototypes are manufactured using commercially available pot cores and tested in an experimental setup

Decoupled control of thrust and normal force in a double-layer single-sided linear induction machine

In this paper, a decoupling method for of the thrust and normal force in a double-layer single-sided linear induction machine (LIM) is presented. The primary is magnetically suspended under and moved along the double-layer secondary which consists of an aluminium plate with a back iron. Therefore, at low slip frequencies, an attractive normal force is produced between the secondary and primary, which is necessary to suspend the primary. In order to decouple the thrust and normal forces, analytical expressions for the forces as function of the slip frequency and the primary current, are obtained by curve fitting on steady-state FEM results. The dynamic behaviour of the LIM is estimated by injecting noise into a transient FE-model. The expressions for the force are used to calculate the required current amplitude and slip frequency for a given force setpoints that are generated by a position controller. Transient FEM simulations show the effectiveness of the decoupling method

Power-optimal force decoupling in a hybrid linear reluctance motor

This paper concerns the power-optimal decoupling of the propulsion and normal force created by a hybrid linear reluctance motor. The intrinsic limitations to the decoupling is addressed by the visualizing each force component with a quadric surface in the Euclidean space which is spanned by the three currents inside the linear motor. If both surfaces intersect, decoupling is possible and infinitely many current vectors exist which results in the desired force values. The search for the vector with the lowest power dissipation is formulated as an optimization problem and solved in real-time using the method of Lagrange multipliers. The intrinsic limitation and force decoupling are shown for a hybrid linear reluctance motor topology, which comprises three separately excited E-core stator segments and a moving salient armature. Transient FE-simulations show that the power-optimal decoupling method results in a maximum position error of 15 µm when the armature is magnetically suspended and propelled underneath the stator segments

Overview of analytical models for the design of linear and planar motors

In this paper, an overview of analytical techniques for the modeling of linear and planar permanent-magnet motors is given. These models can be used complementary to finite element analyses for fast evaluations of topologies, but they are indispensable for the design of magnetically levitated planar motors and other coreless multi-degree-of-freedom motors which are applied in (ultra) high-precision applications. The analytical methods describe the magnetic fields based on magnetic surface charges and Fourier series in two and three dimensions

Optimal design of a pot core rotating transformer

This paper discusses the optimal design of a pot core rotating transformer to replace wires and slip rings in mechatronic systems by means of contactless energy transfer. Analytic models of the transformer are derived in the electromagnetic and thermal discipline. The models are compared with both 2D/3D FEM simulations and measurements. The analytical models are combined and used in a multi-objective sequential quadratic programming algorithm to find the minimal Pareto front in terms of volume and power loss for comparison of the adjacent and coaxial winding topologies. Finally, the optimization algorithm is used for the design of two prototype rotating transformers for a power transfer of 1kW peak, rotating at 4000 rpm. The prototypes are manufactured and tested in an experimental setup