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UBC Theses and Dissertations
Time delay compensation of digital control for switchmode DC power supplies using prediction techniques Bibian, Stéphane
Abstract
The control of switchmode dc power supplies has been traditionally implemented in analog electronics for its low cost, high bandwidth, and proven technology. However, the emergence of advanced microprocessors and Digital Signal Processors (DSPs) has made it possible for power supply manufacturers to consider digital technology a suitable option. As compared to analog control, digital control provides a number of advantages such as reduced susceptibility to aging and environmental variation (temperature, humidity, etc.), better noise immunity, ability to handle complex control schemes and monitoring functions, possibility to implement communication functions for fault and status information, and easy re-programming for different applications. With the downward trend of microprocessor prices and the versatility of the hardware architecture, digital control offers a cost-effective solution which can compete with analog technology. However, one of the major drawbacks of digital control is the limited bandwidth caused by the inherent time delay required for A/D conversion, computation and PWM generation. Such delay degrades the control loop performance, which makes it difficult to comply with technical specifications in many high-performance products. In this thesis, a simple and straightforward predictive technique based on linear extrapolation is presented to compensate for this delay. Two predictive controllers are derived and applied to a full bridge dc power supply. Simulation and experimental results show that the performances of the converter with respect to dc bus ripple and load disturbances can be significantly improved. Those schemes are characterized by a low computational cost which makes them particularly attractive in the demanding real-time environment due to the ever increasing switching frequency of the converter. A similar prediction concept based on a second order parabolic extrapolation is also presented. This predictor substantially reduces the amount of calculation needed to obtain similar results to a conventional controller, thus freeing valuable processor resources. These resources can be used for less critical tasks such as communication and user interface. As a result, the processor is not solely dedicated to the control of the power supply but can incorporate other functions, thus adding functionality and expandability to the system. Finally, this thesis assesses typical digital control issues such as word length, A/D resolution and fixed point programming.
Item Metadata
Title |
Time delay compensation of digital control for switchmode DC power supplies using prediction techniques
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1999
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Description |
The control of switchmode dc power supplies has been traditionally implemented in analog
electronics for its low cost, high bandwidth, and proven technology. However, the emergence of
advanced microprocessors and Digital Signal Processors (DSPs) has made it possible for power supply
manufacturers to consider digital technology a suitable option.
As compared to analog control, digital control provides a number of advantages such as reduced
susceptibility to aging and environmental variation (temperature, humidity, etc.), better noise
immunity, ability to handle complex control schemes and monitoring functions, possibility to
implement communication functions for fault and status information, and easy re-programming for
different applications. With the downward trend of microprocessor prices and the versatility of the
hardware architecture, digital control offers a cost-effective solution which can compete with analog
technology.
However, one of the major drawbacks of digital control is the limited bandwidth caused by the
inherent time delay required for A/D conversion, computation and PWM generation. Such delay
degrades the control loop performance, which makes it difficult to comply with technical
specifications in many high-performance products.
In this thesis, a simple and straightforward predictive technique based on linear extrapolation is
presented to compensate for this delay. Two predictive controllers are derived and applied to a full
bridge dc power supply. Simulation and experimental results show that the performances of the
converter with respect to dc bus ripple and load disturbances can be significantly improved. Those
schemes are characterized by a low computational cost which makes them particularly attractive in the
demanding real-time environment due to the ever increasing switching frequency of the converter.
A similar prediction concept based on a second order parabolic extrapolation is also presented. This
predictor substantially reduces the amount of calculation needed to obtain similar results to a
conventional controller, thus freeing valuable processor resources. These resources can be used for
less critical tasks such as communication and user interface. As a result, the processor is not solely
dedicated to the control of the power supply but can incorporate other functions, thus adding
functionality and expandability to the system.
Finally, this thesis assesses typical digital control issues such as word length, A/D resolution and
fixed point programming.
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Extent |
4779980 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-06-16
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0065283
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1999-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.