Georg von Pfingsten

Iron-Loss Model With Consideration of Minor Loops Applied to FE-Simulations of Electrical Machines

The accurate prediction of iron losses in soft magnetic materials for various frequencies and magnetic flux densities is eminent for an enhanced design of electrical machines in automotive applications. For this purpose different phenomenological iron-loss models have been proposed describing the loss generating effects. Most of these suffer from poor accuracy for high frequencies as well as high values of magnetic flux densities. This paper presents an advanced iron-loss formula, the IEM-Formula, which resolves the limitation of the common iron-loss models by introducing a high order term of the magnetic flux density. Furthermore the IEM-Formula is extended in order to include the influence of higher harmonics as well as minor loops. In line with this a detailed study of minor loop loss behavior is presented. Exemplarily, the iron-loss formula is utilized to calculate the iron losses of a permanent magnet synchronous machine for the drive train of a full electric vehicle.

An Application-Oriented Approach for Consideration of Material Degradation Effects Due to Cutting on Iron Losses and Magnetizability

The decrease in magnetic permeability and increase of local hysteresis loss in the vicinity of lamination edges originating from the cutting process need to be accounted for during the design of electrical machines. A flexible method is needed, which is able to account for different degradation profiles due to different cutting techniques. This paper presents a quantitative analysis of the impact of material degradation on iron losses and magnetizability due to guillotine shear and CO2 laser cutting for non-oriented electrical steels.

Operating Point Resolved Loss Calculation Approach in Saturated Induction Machines

In this paper, the global operating point dependent losses of induction machines are studied by using a local transient loss formulation. The level of flux, the machine is operated at, depends on the operation mode of the inverter. Hence, for precise loss modeling of inverter driven induction machines at the machine design stage, the time and spatial distribution of flux density and the influence of choosing the best operating point is included. A loss scaling method is developed to map iron losses calculated at a single synchronous frequency to other frequencies along the torque–speed map. The modeled losses and operating points are compared to extensive machine measurements. By way of example, the effect of different electrical steel grades tailored either to low losses or preferable magnetizability on the machine performance is investigated.

Influence of Winding Scheme on the Iron-Loss Distribution in Permanent Magnet Synchronous Machines

The influence of the winding scheme [concentrated, single-tooth, distributed (pitched, unpitched)] on the iron-loss distribution in a rotor and stator is to a large extent unknown. At present, windings are primarily selected with respect to back-EMF harmonics and torque fluctuation. In such approaches, the influence of iron losses is disregarded. Moreover, minor loop losses are not covered by most iron-loss models and are therefore ignored. This yields inaccurate results. In particular, for interior permanent magnet machines, the rotor temperature has to be taken into account. For variable-speed drives, losses have to be calculated over the complete operating range. Hence their distribution is studied in this paper for various operating points. The influence of the winding scheme on iron losses and iron-loss distribution is investigated based on finite-element simulations.

Transient approach to model operating point dependent losses in saturated induction machines

In this paper, the global operating point dependent losses of induction machines are studied utilizing a local transient loss formulation. After calculating the local loss distribution, the losses are integrated in space and averaged in time to get the average global losses. The main loss components Ohmic losses, iron losses and friction losses are considered. The Ohmic losses in stator and rotor are dependent on current values and the time- and local-waveform due to current displacement. The iron losses are highly dependent on flux density, base frequency, and harmonic distortion of the flux density. The level of flux, the machine is operated at, depends on the operation mode of the inverter. Hence for precise loss modeling of inverter driven induction machines at the machine design stage, time and spatial distribution of flux density and the influence of choosing the best operating point is included.