DESIGN OF V-SHAPED INTERIOR PERMANENT MAGNETMACHINES FOR HVAC APPLICATIONS

Recent regulatory changes have been proposed to phase down the use of hydrofluorocarbon

(HFC)-based refrigerants in air conditioning and refrigeration systems. The proposed

low global warming potential alternatives (low-GWP) are characterized by lower volumetric

capacities, which require either higher displacements or higher speeds to meet compressor

loads. In order to address this, the coupled optimization of a compressor system and its electric

drive has been proposed. The primary goal of this thesis is to establish tools that can be

used to assess the impact that alternative low-GWP refrigerants have on the sizing and performance

of electrically driven compressors. Toward this goal, a method-of-moments-based

model has been established and structured to enable rapid evaluation of the electromagnetic

performance of V-shaped interior magnet machines. Contributions to the model formulation

include the use of a judicious combination of point and pulse basis functions to evaluate

machine behavior under saturation of stator and rotor steels. Also included is a straightforward

means to include multiple operating points with minimal additional computational

expense. Coupled to the electromagnetic model is a thermal equivalent circuit model that

includes conductive heat transfer between slot winding bundles and stator steel. It also includes

convective heat transfer from the stator to the rotor through the airgap. The proposed

models have been validated using commercial finite-element based software. Subsequently,

they have been applied in design optimization studies used to compare the efficiency and size

(mass) between machines designed for a common HFC refrigerant (R410A) and a proposed

alternative (R454B).