High Efficiency, low copper usage coil designs for electric machines

Normal practice when designing machines is to fill the electric machine’s stator slot with copper in order to minimise the resistance of the coil and hence the heat that they generate (which is wasted). The flexibility and accuracy of the dynamometers in our labs here in Bristol have allowed us to validate non-intuitive ways of putting copper and other materials in the slots of these machines that both minimises material usage and maximises efficiency. This work is now being extended to look at the effect of different materials for the coil windings (such as aluminium) and different, non-uniform 3d structures for coils.

Development of Thermal Models for Use in Machine Controllers/State of Health Estimators 

Modern electric drive applications such as electric vehicles and aerospace applications have to operate over a broad range of duty cycles and operating conditions. This means that the rating of a machine can vary dramatic depending on which of these regions it is operating in. Accurate thermal modelling requires experimental validation. We are currently researching technologies that can dynamically and in real-time, rate the performance of a machine and offer the user time for failure to allow flexible use of smaller machines in a wider range of applications. It was this approach that was used to determine ratings for an electric machine coupled to the rotor of helicopter to offer low, longer term generating capacity as well as fail-safe rotor braking capacity in a range of environmental conditions in an EC project. This work is also of particular interest when electric machines operate at higher switching frequencies and is the basis of a recent EPSRC award in this area.