Optimal passive filter topology for advanced power electronics converters

Power electronic converters are a widely used technology in the processes required for generation, transmission, distribution and consumption of electrical energy. In order to achieve targets of reducing CO2 emissions, the use of power electronic converters is expected to become even more prevalent in all stages of electrical energy use. In the UK, a 2011 government report highlighted that 60% of all electrical energy consumption comes from industrial electric motors. Of the cases where industrial motors are used, half were identified as having the potential for efficiency increases through the application of power electronic converters, which could result in a 9% reduction of national energy consumption. The converters needed for these applications will be connected to the electrical grid and so will be required to conform to regulations limiting the amount of electrical noise they can introduce onto the grid. Meeting these requirements necessitates the use of passive filters, which can be a limiting part of converter designs in terms of size, cost, efficiency and time to develop. As a result, high performance converters will also need high performance filters, and the optimal design of filters is a topic of great importance.
This research will focus on finding new, systematic methods to design optimal filters for grid connected power converters. Optimal filter design is an established topic, however it is often reliant on the design experience of individuals, or costly and time consuming trial-and-error methods. This research would seek to produce a set of methods to allow systematic design of optimal filters for a variety of converter topologies, specifications and designs. These methods would be developed with the intention of forming a design framework to select an optimal filter topology and components, based upon a converter specification. This framework should be able to be automated. Furthermore, methods developed will be intended for use with emerging technologies. These emerging technologies include wide bandgap power devices which can operate at significantly higher frequencies than silicon devices, introducing new challenges for filter designs. Alongside these new power devices, new converter topologies will be explored and included in the developed methods. New topologies of particular interest are multi-level converters, as these influence the optimal filter topology and design. Achieving these goals would decouple optimal filter design from individual designer expertise and trial-and-error design methods, whilst expanding the systematic design methods for use with emerging power converter technologies.
This research primarily comes under the remit of the EPSRC's Electrical Motor and Drives research area, as it explores a technology directly relevant to the industrial electric motor and drives sector, already noted to be a major part of the UKs use of electricity and electrical motors. Due to the broader uses of grid connected power converters, including solar PV inverters, EV chargers and battery electric storage systems, this research has direct parallels to other emerging and established research areas within the EPSRC's Energy research theme.