| Summary: | The School of Electrical, Electronic and Computer Engineering of the North-West University is currently
doing research on active magnetic bearing (AMB) systems. One of the latest developments is the flexible
rotor double radial AMB model. Various studies on the AMB sub-systems are being conducted using the
model.
The focus of this study is on AMB power amplifiers (PAS). The aim is to develop a platform to facilitate
the analysis of the two-state and the three-state switching techniques that are possible for the AMB
switch-mode PAS. An average current controlled PA prototype board is designed to facilitate the study.
The design of the switch-mode PA for the two-state and the three-state switching techniques is conducted
and analysed based on the design specification. The switching techniques are realised in a digital signal
processing (DSP) environment with a TMS320P2812 eZdsp DSP starter kit (DSK). A TMS320P2812
eZdsp DSK is programmed in visSim® development software.
The simulation model for the two switching techniques was developed in MATLAB® simulink. The
simulation models are used to verify the design specifications, to predict the experimental set-up
behaviour and to compare the two-state and the three-state switch-mode PA topologies. The two
switching techniques showed good correlation in system performance, small signal bandwidth and power
bandwidth. The simulation models' responses are also in agreement with the theoretical analysis.
Testing of the PA's switching techniques was conducted on the double radial AMB system. The two
switching techniques are analysed on the basis of how well they can regulate the coil current. The power
bandwidth as well as the power loss analysis was used to evaluate the two switching techniques.
The experimental results showed good correlation with the simulation results in terms of the dynamic
response and the power losses. The power bandwidth measurements could not be performed at the
specified dc levels due to noise problems. The power bandwidth prediction was however verified by
reducing the voltage level to minimum values and the switching frequency to lower value.
Recommendations for future improvements on the PAS are given based on the results. === Thesis (M.Ing. (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2006.
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