A discrete elements model for ironless DC-machines with graphite brushes

Highly dynamic DC-machines, used in low power applications, often contain ironless or so called bell shaped windings. Because there is no massive iron core to support the windings, one of the limiting factors for the torque of the machine is the force on the single wires of the copper weave. Therefore, the knowledge of the force distribution on the single wires could be a helpful design criterion. In order to examine the distribution of forces inside bell shaped windings, in this work the coil wires are subdivided into discrete wire elements within this work. For each of these elements the Lorentz-force and the torque caused by a permanent magnet excitation are calculated. To calculate the currents through the elements a time variant electrical network is presented, which is also capable to consider non-ideal commutation effects. The model itself consists of two single blocks, which will be explained below.