Perturbation Finite Element Method for Efficient Copper Losses Calculation in Switched Reluctance Machines

Abstract

Copper losses dissipated in the windings of electric machines are the sum of classical ohmic DC losses and additional AC eddy current losses. In fact, the level of eddy current losses is strongly correlated to the manner of disposition of coil conductors in machine slots. Then, to improve the efficiency in electric machines, the selection of an optimal winding configuration becomes substantial. Since eddy current losses derive from the strong electromagnetic coupling between current density and time-dependent magnetic field which cannot be solved easily, numerical analyses such as particularly the one using the finite element method are often used. As for the finite element modeling, it can employ moving band technique to perform the rotor motion and Newton-Raphson iterations to deal with the nonlinear behavior of magnetic circuits. It leads then to a substantial computational time that hinders any process of conception or optimization of winding geometries. To overcome this issue, a 2D finite element model reduction based on the perturbation method is proposed. It starts from one approximate finite element solution of a simplified complete machine modeling to find fast but accurate solutions in slots subdomains when any variation of geometrical or physical data occurs. It allows adapting nonconforming meshes and provides clear advantages in repetitive analyses when we search the optimized winding configuration for a given number of turns.

Calculation of Losses in a Motor Fed by a Conventional Inverter and a Battery Distributed Inverter

“…In the same way as for the iron losses, a model directly under Matlab is used to carry out the finite element calculations. A magneto-static resolution and a simplified geometry in a magneto-dynamic resolution are coupled [26]. For this loss calculation, two different meshes are used.…”

Electromagnetic performance analysis and thermal research of an outer‐rotor I‐shaped flux‐switching permanent‐magnet motor with considering driving cycles

“…Hence, it is extremely crucial to calculate the losses for determining an exact heat source. Based on this, the specific studies are focused on loss prediction and calculation [18][19][20]. In [18], an iron loss calculation method is proposed and analysed for a high-speed PM motor, which is built on a foundation of flux variation locus.…”

“…Apart from the investigations of iron loss, copper loss analysis is also involved. In [20], a copper loss analysis is presented for a switched reluctance machine. By integrating the perturbation finite element (FE) method into the investigation process, an efficient prediction, and calculation of the winding copper loss is realised.…”

Ultra-High-Dimensional Multi-Level Optimization Strategies for Electrical Machines

“…Meanwhile, the magnetic saturation and leakage cannot be considered fully. Thus, FEA is normally used for motor performance calculation [9][10]. As the simulation of FEA may be time-consuming for many situations, the total computation cost in the optimization is normally huge, especially for highdimensional problems.…”