The McTronX research group, at the Potchefstroom campus of the North–West University, has
been researching Active Magnetic Bearings (AMBs). A fully suspended, flywheel energy storage
system (FESS) has been developed. Due to excessive unbalance on the rotor, the motor drive
could not be tested up to its rated speed. In the interim, until the rotor can be balanced and
other rotor dynamic effects have been investigated, the group decided that the existing drive
control should be improved and tested on a high–speed permanent magnet synchronous motor
(PMSM), using normal roller element bearings.
In order to test the motor control a second (identical) PMSM, mechanically coupled to the
former, operates in generator mode which serves as the torque load. Two different control algorithms,
namely V/f and vector control, are designed and implemented on a rapid control
prototyping system, i.e. dSPACE®. The V/f control is an open–loop, position sensorless technique,
whilst the vector controller makes use of a position sensor.
From the design and implementation it became clear that the vector control is more robust,
in the sense that it is less sensitive on parameter variations and disturbances. It can start up
reliably even under full load conditions.
The V/f control is an attractive alternative to the vector control, especially in AMB systems,
where it may be difficult to mount the position sensor, has to operate in a hazardous environment
not suited to the sensor or could degrade the reliability of the AMB system. The cost of the
position sensor is not really a concern compared to the cost of an AMB system. The V/f control
is more suited to fan and pump applications, which has a low dynamic requirement. The V/f
control has high startup currents and is not recommended for applications requiring a high
starting torque or fast acceleration during operation.
The inverter, which drives the PMSM, also had to be developed. With regard to the motor
control, the effects of inverter non–idealities had to be accounted, especially for the V/f control.
The implemented control algorithms were tested up to 20 krpm. Discrepancies between the expected
and actual results are discussed. Overall, the controllers performed as desired. Generally,
the project goals have been reached satisfactorily. / Thesis (M.Ing. (Computer and Electronic Engineering))--North-West University, Potchefstroom Campus, 2011.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:nwu/oai:dspace.nwu.ac.za:10394/7609 |
| Date | January 2011 |
| Creators | Kruger, Gert Lodewikus. |
| Publisher | North-West University |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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