Loss Calculation for Electrical Machines Based on Finite Element Analysis Considering 3D Magnetic Flux

In order to increase torque and power density, novel electrical machines with a 3D magnetic flux path are used. One of them is the transverse flux machine, which offers high torque at low speed and therefore is predestined for use as near-wheel drive in an electrical vehicle or as a joint drive for a robot arm. In contrast to typical machines, such as a synchronous machine, the magnetic flux has a component transverse to the radial plane. Additionally, the materials are highly saturated to achieve the high power density. The aim, beside high power and torque density, is to reach high efficiency. This is especially necessary for mobile applications with batteries, such as an electrical vehicle or a mobile robot. Hence, the losses have to be calculated during the machine optimization process in finite element analysis. Beside, the copper losses the iron losses have to be considered. For these reasons this paper presents a method to calculate iron losses in electrical machines with 3D flux path. Alternating and rotational magnetic fields are considered, as well as the influence of saturation. The computation method of iron losses is performed exemplary on a transverse flux machine. The results are compared with the measurements of the transverse flux machine on the test bench.