PhD ThesisThe integration of passive components such as inductors and capacitors has gained significant
popularity in integrated drive research, and future power electronics systems will require more
integrated and standardised packages. These give rise to better power density and improved
performance. However, packaging techniques and passive components have been considered a
technological barrier which is limiting advances in power electronics. The focus on size
reduction should be turned towards the passive components, such as converter chokes, DC-link
capacitors and electromagnetic interference (EMI) filters, and achieving greater power density
depends on innovative integration concepts, flexibility in structures and extended operating
temperature ranges while system integration and modularity are not mutually exclusive.
This research considers the possibility of integrating input power filter components into electric
machines. Particular attention is paid to the integration of electromagnetic line filter inductors
to give better utilisation of the motor volume and envelope. This can be achieved by sharing
the machine’s magnetic circuit. An LCL line filter has been chosen to be integrated with a gridconnected permanent magnet synchronous machine. Machines have been proposed in this study
for low speed (3000 RPM) and high speed (25000 RPM) operation. The two machines have
similar dimensions, but the low-speed machine is less challenging in terms of losses and filter
integration, so attention is directed more to the high-speed machine. Both are supplied with
low- and high-power drives at power ratings of 4.5 kW and 38 kW respectively.
Several novel techniques have been investigated to integrate filter inductors into the electrical
machines to produce a single mechanically packaged unit without significant increases in size
and losses. Different approaches have been simulated using finite element analysis (FEA) to
assess the effectiveness of the integration of passives within the machine structure. Each design
has been iteratively optimised to determine the best mass of copper and core for the integrated
filter inductors, targeting parity in power density when compared to traditional separate
packages. The research demonstrates that an approach utilising a double-slot stator machine
(named the integrated double slot (IDS) machine) with input filters wound into the outermost
slots is the most appropriate choice in terms of achieving higher power density.
The integrated filter inductors mimic the electromagnetic behaviour of the discrete industrially
packaged inductors but with a volume reduction of 87.6%. A prototype of the IDS machine
design of a 38 kW, 25000 RPM, including filter inductors was manufactured and testedthe General Electricity Company of Libya
(GECOL), the Engineering and Physical Sciences Research Council (EPSRC), and the
Engineering Doctorate scheme at Newcastle University