liu.seSearch for publications in DiVA
Change search
ReferencesLink to record
Permanent link

Direct link
System analysis of a diesel engine with VGT and EGR
Linköping University, Department of Electrical Engineering.
2005 (English)Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
Abstract [en]

To fulfil emission requirements specified by environment demands, such as Euro 4 and Euro 5, there is a need to utilize engines based on technologies such as Variable Turbine Geometry (VGT) and Exhaust Gas Recirculation (EGR). A model of an engine using VGT and EGR was created by Ph.D student Johan Wahlström at Linköping University. This thesis evaluates Wahlström's model and shows how it successfully describes the engine and its behaviour. The thesis also confirms theories about the occurrens of non.minimum phase behaviour in different transfer functions, e.g. from VGT signal to the mass flow through the compressor.

An interesting phenomenon when applying VGT and EGR is a nonlinearity leading to, for example, that the same pressure in the intake manifold can occur for two different VGT signals. Such phenomenon can cause problems when designing a control system. Furthermore, this nonlinearity also results in a replacement of the nonminimum phase behaviour with an overshoot when a large (above 80%) VGT control signal is used.

This thesis also provides a linearized model, which describes the engine satisfactory. The linearization results in transfer functions with two zeros and three poles, whose locations do not change much when varying engine speed and load (except at high load and low engine speed). This fact will most likely make it possible to utilize just a few different linearizations for all speeds and loads. However, altering VGT and EGR positions greatly affect the transfer functions. Thus, several linearizations are probably needed to cover all operating points.

When designing a future control system a good strategy is to utilize a decoupled system since the model has strong cross-connections. Another solution would be to apply multi dimensional control strategy, e.g. LQ-theory.

Place, publisher, year, edition, pages
Institutionen för systemteknik , 2005. , 65 p.
Keyword [en]
diesel engine, VGT, EGR
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:liu:diva-5438ISRN: LiTH-ISY-EX--05/3714--SEOAI: diva2:21311
Available from: 2006-01-16 Created: 2006-01-16

Open Access in DiVA

fulltext(2169 kB)893 downloads
File information
File name FULLTEXT01.pdfFile size 2169 kBChecksum SHA-1
Type fulltextMimetype application/pdf

By organisation
Department of Electrical Engineering
Other Electrical Engineering, Electronic Engineering, Information Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 893 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 885 hits
ReferencesLink to record
Permanent link

Direct link