A measurement setup is designed and constructed to experimentally investigate the
thermohydraulic performance of a novel direct rotor cooling method for an interior
permanent magnet synchronous machine, where oil is pumped through weight saving channels
of the rotor iron close to the magnets. The setup consist of a stationary rotor assembly
where heat is dissipated in an aluminum sleeve surrounding the rotor outer surface.
Measurements are performed for different oil inlet temperatures, flow rates and heat
losses. It is shown that tangential temperature variations can be neglected and axial
variations are as expected. The conductive resistance within the rotor assembly is
similar for each measurement point as the differences are within the measurement uncertainty.
The convective resistance decreases with an increasing flow rate, inlet temperature
and heat dissipation. From correlations in scientific literature, it is expected that
the convective resistance will further reduce with increasing rotational speed of
the rotor. A comparison of these results to a standard hollow shaft cooling method
shows a great potential of the novel direct rotor cooling method to further increase
the power density of electric machines.
