Many types of devices based on power converters have been proposed and studied for utility applications. In recent years most of the control systems for these converters have been digital. Unfortunately, such digital controllers, which are often based on a digital signal processor (DSP), are difficult to model in simulation. Thus, hardware prototypes are usually required. This thesis presents a tool for fast prototyping that helps overcome these difficulties. Namely, a hardware-in-the-loop simulation is provided for the digital controller in order to evaluate control algorithms without the voltage source converter and power system. The controller in the loop design methodology is described and the division between the real-time power system model and the hardware controller with an interface is shown. Also, the modulation type, integration time step selection and synchronization between the controller and the real-time system simulation are discussed. The hardware configuration for the real-time simulator and the software implementation of the simulator is discussed. In this thesis an example application of a shunt active compensator following this formal procedure is presented. The active compensator prototyping was first developed in MATLAB/Simulink. Then, following a formal design procedure, the power system was modeled in a digital simulator and the controller was implemented in a digital controller board. Finally, a hardware-in-the-loop test was carried out to validate the performance of the hardware controller for the active compensator. Although the tools and methods presented here are aimed at shunt connected current controller application, they may be generalized for use in the development of any digitally controlled power electronic converter.

This thesis derives a first approximation model that will describe the flow of fluid in microfluidic devices such as in microchannels, microdiffusers and micronozzles using electrical network modelling. The important parameter that is of concern is the flow rates of these devices. The purpose of this work is to contribute to the physical component of our interactive Virtual Reality (VR)-prototyping tool for MEMS, with emphasis on fast calculations for interactive CAD design. Current calculations are too time consuming and not suitable for interactive CAD with dynamic animations. This work contributes to and fills the need for the development of MEMS dynamic visualisation, showing the movement of fluid within microdevices in time scale. Microfluidic MEMS devices are used in a wide range of applications, such as in chemical analysis, gene expression analysis, electronic cooling system and inkjet printers. Their success lies in their microdimensions, enabling the creation of systems that are considerably minute yet can contain many complex subsystems. With this reduction in size, the advantages of requiring less material for analysis, less power consumption, less wastage and an increase in portability becomes their selling point. Market size is in excess of US$50 billion in 2004, according to a study made by Nexus. New applications are constantly being developed leading to creation of new devices, such as the DNA and the protein chip. Applications are found in pharmaceuticals, diagnostic, biotechnology and the food industry. An example is the outcome of the mapping and sequencing of the human genome DNA in the late 1990's leading to greater understanding of our genetic makeup. Armed with this knowledge, doctors will be able to treat diseases that were deemed untreatable before, such as diabetes or cancer. Among the tools with which that can be achieved include the DNA chip which is used to analyse an individual's genetic makeup and the Gene chip used in the study of cancer. With this burgeoning influx of new devices and an increase in demand for them there is a need for better and more efficient designs. The MEMS design process is time consuming and costly. Many calculations rely on Finite Element Analysis, which has slow and time consuming algorithms, that make interactive CAD unworkable. This is because the iterative algorithms for calculating the animated images showing the ongoing proccess as they occur, are too slow. Faster computers do not solve the void of efficient algorithms, because with faster computer also comes the demand for a fasters response. A 40 - 90 minute FEA calculation will not be replaced by a faster computer in the next decades to an almost instant response. Efficient design tools are required to shorten this process. These interactive CAD tools need to be able to give quick yet accurate results. Current CAD tools involve time consuming numerical analysis technique which requires hours of numerous iterations for the device structure design followed by more calculations to achieve the required output specification. Although there is a need for a detailed analysis, especially in solving for a particular aspect of the design, having a tool to quickly get a first approximation will greatly shorten the guesswork involved in determining the overall requirement. The underlying theory for the fluid flow model is based on traditional continuum theory and the Navier-Stokes equation is used in the derivation of a layered flow model in which the flow region is segmented into layered sections, each having different flow rates. The flow characteristics of each sections are modeled as electrical components in an electrical circuit. Matlab 6.5 (MatlabTM) is used for the modelling aspect and Simulink is used for the simulation.

<p>There is a gap between low-fidelity prototyping using paper and high-fidelity prototyping using computers in web design. Both serve well in different stages of web design, but are not well integrated. Prior studies have examined the practice of web designers. The studies resulted in a number of alternative prototyping tools, which focus on informal representation and try to prolong sketching in the design process.</p><p>The thesis proposes a design of a prototyping tool that makes use of existing paper sketches. In paper prototyping, a human who acts as the “computer” makes the sketches interactive. In the prototyping tool put forward in the thesis, the interactivity of the sketches is instead created on the computer. The novel prototyping tool needs to support the interactions and behaviours used in web design, and it must be easy to use so that the web designers do not have to invest too much time learning it.</p><p>The prototype of the tool is a sketch-and-scan interface, thus allowing the use of paper the way it is. The functionality supports both documentation and computer interactivity. Usability tests and expert reviews were conducted, involving students, lecturers and researchers in human-computer interaction.</p><p>The results elaborate previous research on prototyping practice, and a designers’ wish list was formulated. A prototyping tool is expected to support communication between users, designers and developers; as well as to reduce a designer’s need to change his work practice when using the tool.</p>

There is a gap between low-fidelity prototyping using paper and high-fidelity prototyping using computers in web design. Both serve well in different stages of web design, but are not well integrated. Prior studies have examined the practice of web designers. The studies resulted in a number of alternative prototyping tools, which focus on informal representation and try to prolong sketching in the design process. The thesis proposes a design of a prototyping tool that makes use of existing paper sketches. In paper prototyping, a human who acts as the “computer” makes the sketches interactive. In the prototyping tool put forward in the thesis, the interactivity of the sketches is instead created on the computer. The novel prototyping tool needs to support the interactions and behaviours used in web design, and it must be easy to use so that the web designers do not have to invest too much time learning it. The prototype of the tool is a sketch-and-scan interface, thus allowing the use of paper the way it is. The functionality supports both documentation and computer interactivity. Usability tests and expert reviews were conducted, involving students, lecturers and researchers in human-computer interaction. The results elaborate previous research on prototyping practice, and a designers’ wish list was formulated. A prototyping tool is expected to support communication between users, designers and developers; as well as to reduce a designer’s need to change his work practice when using the tool.