Modeling linear or nonlinear magnetic materials in the rotor. Further, the nonlinear saturation curve can be defined externally with the External Material feature, found in the Materials node under Global Definitions. The B-H curve is usually defined in the Materials node, for example, within Soft Iron (without losses). In the constitutive relation, you can either set it as a linear material with finite (constant) permeability or change it to a nonlinear material using the B-H Curve option. In the next step, add another Magnetic Flux Conservation feature and assign it to the rotor iron. The constitutive relation is set to the linear material with Relative permeability, referencing the Air material in the Materials node. To begin, add the first Magnetic Flux Conservation feature and assign it to the rotor side’s air region and the stator side’s air region next to the identity pair. Invalid topology where the MSP region is not simply connected. Such a topological issue should be avoided. A closed curve in the MSP region “chains” an MVP region that is carrying a current (stator coil). Illustrated below is an invalid topology example where the entire air region is assigned an MSP. In other words, they do not include any MSP regions containing a closed loop that “chains” the current-carrying conductor. If you wish to compute the eddy current losses both on the stator and rotor iron (or if you have any other conducting domains in the rotor), you must also solve for those regions with MVP, as illustrated in the above figure on the right.įor both configurations, the MSP regions are simply connected. The same, however, cannot be said for the rotor iron, as it is an MSP formulation and explicitly assumes that there is no current in the regions. Since the MVP formulation allows for current-carrying domains, it is possible to model the stator iron region for the induced eddy currents and compute the eddy current losses. Using this setup, you can model the entire MVP region with the Ampère’s Law feature. The rotor iron, permanent magnet, and air region of the rotor, as well as a part of the stator’s air region, are modeled with MSP. In the above image on the left, the stator coil, stator iron, and air region on the stator side are modeled with MVP. The MSP and MVP regions, along with an identity pair boundary. You can do so by utilizing the Magnetic Flux Conservation feature in the Rotating Machinery, Magnetic interface. Therefore, it is important to solve an air region on either side of the identity pair through the MSP. The MSP formulation introduces fewer degrees of freedom and ensures a more accurate coupling of the magnetic flux density when used with a pair feature like Continuity or Sector Symmetry. The same formulations are used in the Magnetic Fields and the Magnetic Fields, No Currents interfaces, respectively. The Rotating Machinery, Magnetic interface uses two approaches (mixed formulation) to solve Maxwell’s equations: the magnetic vector potential (MVP) and the magnetic scalar potential (MSP). Within the same branch, you can also define coordinate systems to use in the physics setup. These selections are reused throughout the model component for physics, meshing, and postprocessing. In the Definitions branch, define the selections for geometric entities, such as domains or boundaries. Various selections for domains and boundaries are shown in the Definitions node. Identity pair settings for separating the stator and rotor domains when the geometry is finalized via Form Assembly. Unions of the rotor and stator domains in the geometry sequence. (The 2D model does not capture this element.) In 3D, the air region is added around the stator-end winding to capture the fringing fields. Form Assembly is used to finalize the geometry, automatically creating identity pairs under Definitions. Two separate unions are formed for the different regions. This is typically achieved by splitting the air gap between the parts. Thus, when modeling such a machine, its geometry must be cut into two parts. Rotating magnetic machines consist of two parts: a stator and a rotor. Parameters included in the simulation of an AC generator. Next, define your Parameters, including length, number of sectors, wire diameter, and rpm. For this AC generator example, choose the 3D modeling space and then select the Rotating Machinery, Magnetic interface and the Stationary study type. Using the 3D sector geometry discussed above, we will highlight the key steps behind modeling a rotating machine. Important Steps for Modeling a 3D Rotating Machine Right: Sector geometry of the AC generator. Left: Cross-section geometry of an AC generator in 2D.
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