Past seminars at IEA in 2019

Past seminars in 2022, 2021, 2020, 2019, 2018, 2017, 2016, 2015, 2014, 2013, 2012, 2011, 2010, 2009, 2008, 2007, 2006, 2005, 2004, 2003, 2002, 2001, 2000, 1999, 1998

Abstract:
As automation systems grows in number and scope, in particular as a result of systems being connected to and interacting with each other, the number of situations where various systems may perform in ways that were not intended increases. This situation is considered being mainly the result of increased complexity. This thesis studies the concept of complexity from a technical perspective and aims at classifying the types of complexity present in industry today. It also tries to propose methods for handling the design of automation systems with inherent complexity. The method chosen is to present a hypothesis and try to verify it by applying the principles to a number of manufacturing processes that has been identified by the author from personal experience of the processes. Finally, the methods are exemplified by some simple mathematical examples of selected control units.

Supervisors:
Assoc. Prof. Ulf Jeppsson (Lund University, Lund, Sweden)
Assoc. Prof. Gunnar Lindstedt (Lund University, Lund, Sweden)

Opponent:
Prof. Erik Dahlquist (Mälardalens Högskola, Västerås, Sweden)

Abstract:
This thesis presents methods to derive and model the performance characteristics of interior permanent magnet machines - a machine type which is commonly used for propulsion of electrical vehicles. The thesis divides the performance characteristics into three subcategories: The electromagnetic properties, the loss profile and the thermal behaviour of the machines. One separate characterisation method is presented for each subcategory. However, all three methods have in common that they use data solely from mechanical or thermal transient operation. The methods aim to derive the characteristics with as little and as cheap equipment as possible, and to minimise the duration of the tests.

The procedure that derives the electromagnetic properties uses measurements from when the test objects accelerate and brake. The method obtains the relationship between the current and the linked magnetic flux in the stator windings with relatively small means, and it does not demand a brake machine or a power analyser. Furthermore, due to the low time duration of the tests, the method is well suited to derive the temperature dependence of the current/flux relationships. The loss profile of the machine is derived with a similar method as the magnetic model, but requires lower mechanical dynamics. Therefore, the method generally requires an increase of the moment of inertia of the rotating parts of the machines. This is typically achieved by mounting flywheels on the shafts of the test objects. The method yields results that are well suited to use as identification data for loss models of the machines. The thermal characteristics of the test objects are obtained from temperature measurements during transient thermal conditions. The measured data are used to derive an equivalent circuit that describes the thermal behaviour of the test objects well.

Supervisors: Prof. Mats Alaküla, Assoc. Prof. Avo Reinap
Opponent: Assoc. Prof. Pia Lindh

Abstract:
Recent years have proven the benefits of electrifying the road bound vehicle fleet. With new components entering, the general understanding as well as the components as such needs to be improved. Focus in the thesis is on the design of an electric machine based on specifications of requirements for a commercial heavy vehicle such as a truck or a bus. One strict requirement is that the machine has to fit in the vehicle without compromising the performance. Besides limitations on the size, this affects the power density and hence efficiency and cooling. Another characteristic of a traction machine is the difference between peak operation and average or continuous loading. Within the automotive sector, cost is also an important factor. Prior to the design work, pre-studies are used to acquire good understanding of the intended applications. The result is a space claim of Ø220 mm times 400 mm and a peak power of 180 kW. By designing the machine with a top speed of almost five times that of a conventional heavy duty engine, the required power levels are reached with less torque. As torque is proportional to size, the power demand is reached with a smaller and hence also less expensive machine. The design work is done in a two dimensional finite element environment partly developed at the division at Lund University. Main focus is on the limited space claim and requested peak power. Cooling is done with oil directed to the active parts of the machine. Prototype testing proves the machine to be capable of propelling a heavy commercial vehicle. Some in depth studies are also done on torque ripple in the skewed machine and on mapping of the losses. The thesis presents the thorough work on setting the requirements, designing, prototyping and testing an interior permanent magnet machine intended for propulsion of heavy commercial vehicles. Improvements implemented in the design tool is verified with measurements. A deeper study on the torque output from the skewed machine shows a load dependant influence with larger impact in the field weakening region. It is also found larger than expected from the analytical expression in relevant text books. The losses are mapped with main focus on the speed dependant parts. A review of how manufacturing processes and machine controls affect the iron losses is presented. The iron loss model is adapted based on test results. Losses in the windings and in the rotor are included in the study as well.

Supervisor:
Prof. Mats Alaküla (Lund University)

Opponent:
Senior Research Associate Rafal Wrobel (Newcastle University)