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Control of surge currents in inverter fed loads Venalainen, Jarmo
Abstract
Switch mode power converters have been used in high power applications such as DC links and variable frequency motor drives for a number of decades. In these applications the load is fixed and well known, and therefore the nature of the power demand placed on the inverter is also well known. In more recent years, high frequency switch mode inverters have become available at smaller power levels as consumer products. These inverters are marketed as capable of providing AC power to ANY AC load which the customer may have. In this case the inverter is called upon to supply power to a diverse variety of loads, presenting it with very challenging operational issues, especially with regards start up surge currents. This thesis investigates the characteristics of the input current drawn by consumer type AC loads, when driven by a standard sinusoidal 60 Hz 110VAC source, with particular emphasis on the inrush current transients found during start up. It then goes on to look at how the surge currents differ when the driving voltage is a non-sinusoidal single step waveform as produced by the vast majority of small inverters. This is followed by a discussion on the benefit of having multiple step waveforms and trapezoidal waveforms, in terms of their effect on the surge current transients. From the discussion on multi step and trapezoidal waveforms, it is shown that a current regulated output is the optimum solution for small modified sinewave inverters when they are used to drive typical consumer type loads. This approach is demonstrated in a 300W inverter through the implementation of hysteretic output current control. Finally, AC output bridge switching losses are investigated, and the benefit of a small amount of series output inductance is demonstrated through simulations and circuit trials.
Item Metadata
Title |
Control of surge currents in inverter fed loads
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2000
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Description |
Switch mode power converters have been used in high power applications such as DC
links and variable frequency motor drives for a number of decades. In these applications the
load is fixed and well known, and therefore the nature of the power demand placed on the
inverter is also well known. In more recent years, high frequency switch mode inverters have
become available at smaller power levels as consumer products. These inverters are
marketed as capable of providing AC power to ANY AC load which the customer may have.
In this case the inverter is called upon to supply power to a diverse variety of loads,
presenting it with very challenging operational issues, especially with regards start up surge
currents.
This thesis investigates the characteristics of the input current drawn by consumer type
AC loads, when driven by a standard sinusoidal 60 Hz 110VAC source, with particular
emphasis on the inrush current transients found during start up. It then goes on to look at
how the surge currents differ when the driving voltage is a non-sinusoidal single step
waveform as produced by the vast majority of small inverters. This is followed by a
discussion on the benefit of having multiple step waveforms and trapezoidal waveforms, in
terms of their effect on the surge current transients. From the discussion on multi step and
trapezoidal waveforms, it is shown that a current regulated output is the optimum solution for
small modified sinewave inverters when they are used to drive typical consumer type loads.
This approach is demonstrated in a 300W inverter through the implementation of hysteretic
output current control. Finally, AC output bridge switching losses are investigated, and the
benefit of a small amount of series output inductance is demonstrated through simulations
and circuit trials.
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Extent |
10304125 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-07-20
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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 |
10.14288/1.0065180
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2000-11
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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.