13-08-2012, 03:40 PM
Comprehensive Study of Single-Phase AC-DC Power Factor Corrected Converters With High-Frequency Isolation
Comprehensive Study of Single-Phase AC-DC.pdf (Size: 2.05 MB / Downloads: 57)
Abstract
Solid-state switch mode AC-DC converters having
high-frequency transformer isolation are developed in buck, boost,
and buck-boost configurations with improved power quality in
terms of reduced total harmonic distortion (THD) of input current,
power-factor correction (PFC) at AC mains and precisely
regulated and isolated DC output voltage feeding to loads from few
Watts to several kW. This paper presents a comprehensive study
on state of art of power factor corrected single-phase AC-DC converters
configurations, control strategies, selection of components
and design considerations, performance evaluation, power quality
considerations, selection criteria and potential applications, latest
trends, and future developments. Simulation results as well as
comparative performance are presented and discussed for most of
the proposed topologies.
Index Terms—AC-DC converters, harmonic reduction, high-frequency
(HF) transformer isolation, improved power quality converters,
power-factor correction.
I. INTRODUCTION
SOLID state AC-DC converters with high-frequency (HF)
transformer isolation is extensively used in switched mode
power supplies (SMPS), uninterruptible power supplies (UPS),
welding units, battery charging, induction heaters, electronic
ballasts, power supplies for telecommunication systems, measurement
and testing equipments, small rating adjustable speed
drives (ASDs) in biomedical equipments, small rating refrigeration,
heating, ventilation and air conditioning (HVAC), etc.
Conventionally, these AC-DC converters are developed in two
stages. In the first stage, AC voltage is converted into an uncontrolled
DC voltage using diode rectifiers, which is cascaded with
the second stage of isolated DC-DC converters using HF transformer
for isolation. These two-stage AC-DC converters have
Manuscript received July 20, 2011; accepted August 05, 2011. Personal use
of this material is permitted. However, permission to use this material for any
other purposes must be obtained from the IEEE by sending a request to pubspermissions@
ieee.org. Paper no. TII-11-327.
B. Singh is with the Department of Electrical Engineering, Indian Institute of
Technology Delhi, NewDelhi, 110016, India (e-mail: bhimsinghr[at]gmail.com).
S. Singh is with the Department of Electrical and Instrumentation Engineering,
Sant Longowal Institute of Engineering and Technology, Longowal,
Sangrur, Punjab-148106, India (e-mail: sschauhan.sdl[at]gmail.com).
A. Chandra and K. Al-Haddad are with the Département de génie électrique,
ÉTS, 1100, Montréal, QC H3C 1K3, Canada (e-mail: chandra[at]ele.etsmtl.ca;
kamal[at]ele.etsmtl.ca).
Color versions of one or more of the figures in this paper are available online
at http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/TII.2011.2166798
the problems of power quality in terms of injected harmonic currents
at AC mains, caused voltage distortion, degraded powerfactor,
high crest factor, and large size of DC capacitor filter
at first stage. However, in view of their increasing applications,
these AC-DC converters are being developed in single-stage to
improve power quality, reduced number of components and high
efficiency. Moreover, due to strict requirements of improved
power quality at input AC mains several standards [1], [2] have
been developed and are enforced on the consumers. However,
power quality at AC mains can be improved using filters in existing
installations but it increases cost, size, weight, and losses
in the system. These problems can be avoided using newly developed
single-stage improved power qualityAC-DC converters
with HF transformer isolation. They are also known as input current
shapers, high power-factor single-stage converters, powerfactor
correction (PFC) converters, universal input single-stage
PFC isolated converters, etc. Moreover, this newbreed of singlestage
converters is being reported in new books [3]–[9], seminars,
and many recent publications [10]–[19]. Therefore, it is
considered relevant to present a comprehensive state of art on
the improved power quality AC-DC converters with HF transformer
isolation for the benefits of practice, application, and design
engineers using them in wide varying applications ranging
from few Watts to several kWs.
This paper deals with an exhaustive review of IPQCs with
HF transformer isolation. More than 150 publications are
classified into nine major categories. The first category [1]–[19]
is a general on power quality standards, texts, tutorials and
comparative topology publications. Second to ninth categories
publications include single-phase buck, boost and buck-boost
AC-DC converters. The buck type converters are further
classified to forward, push-pull, half-bridge and full-bridge
configurations. The boost type converters are also classified
in forward, push-pull, half-bridge, and full-bridge converter
topologies. The buck-boost type converters are subclassified
into flyback, Cuk, SEPIC, and Zeta converters. Total numbers
of circuit topologies of these converters are divided into 12
categories. The designs of various IPQCs with HF transformer
isolation and their validation through simulation are also presented
in the paper to demonstrate the performance of various
converters and strengthen the review of IPQCs. The paper is
presented in ten sections including introduction and conclusion.
The other sections include a state of art on these converters,
their configurations, control strategies, components selection
and design, performance evaluation, comparative features,
1551-3203/$26.00 © 2011 IEEE
This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination.
2 IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS
potential applications, selection considerations for specific
applications, latest trends, and future development.
II. STATE-OF-THE-ART
AC-DC converters employing HF transformer isolation are
developed in wide power ratings from fraction of Watt to several
kW to feed DC power in computer power supplies, UPS,
battery chargers, induction heating, welding units, electronic
ballasts, medical equipments, small rating ASDs in fans, compressors,
and telecommunication applications. This family of
power supplies is developed to improve power quality in terms
of low value of THD and crest factor of input current, high
power-factor, low EMI and RFI at AC mains and regulated,
reduced ripple and stabilized DC output voltage under varying
loads. These converters are explored in last decade in variety
of control strategies [5], [6], magnetic [3], [4], [7], circuit
integration [6], [7], ASIC developments [7], configurations
[10], [12], [14]–[17], current conduction modes [13], electronic
ballast and DC regulator applications [14], circuit and components
count optimization [18], use of DSP and microcontrollers
[19], enhanced reliability and high efficiency in buck, boost
and buck-boost topologies with HF transformer isolation for
voltage matching, multiple outputs, reduction in size, losses,
weight, etc. A number of circuit configurations have been
developed to meet specific requirements of large number of applications
along with a high level of power quality at input AC
mains and output DC loads. This section consists of sequence
of development and status of these types of AC-DC converters
technology integrating HF isolation.
Because of excessive use of AC-DC converters in a number
of applications, the power quality has become important to
maintain clean power supply to the consumers. Depending
upon the voltage levels, the AC mains voltage is converted into
DC power to feed variety of loads through these single-phase
isolated AC-DC converters, classified into three major categories,
namely, single-phase buck, boost, and buck-boost
configurations with improved power quality at input AC mains
and output DC load.
TheseAC-DC converters are developed using HF transformer
isolation with single or multiple outputs in buck and boost categories,
namely, forward, push-pull, half-bridge and full-bridge
and in buck-boost configurations of flyback, Cuk, SEPIC, and
Zeta types of converters. They are available in varying power
from mW to several kW for the use in small instruments to
telecommunication power supplies. Furthermore, the advancement
in integrated magnetics technology employing several inductors
and HF transformer into one core provides a compact,
small size, low-cost and reduced component count, modular and
efficient AC-DC converters for use in computers and other similar
sectors.
One of the important reasons for such tremendous development
of these isolated AC-DC converters is the availability of
HF (in the range of hundreds of kHz) solid-state switching device,
namely, MOSETs [5] which have a high level of performance
because of their high switching capability with almost
negligible losses. However, in few applications specially designed
BJT (bipolar junction transistor) and IGBTs (insulated
Fig. 1. Classification of improved power quality single-phase AC-DC converters
with HF transformer isolation.
gate bipolar transistor) are used with reasonable switching frequency
(in the range of tens kHz). Moreover, many manufacturers
are developing dedicated power modules for the use in
specific converters to reduce their losses, size, weight, and cost.
Another set of important components required in these converters
technology is sensing devices used in feedback current
and voltage loops. Because of heavy cost constraints, a low-cost
current and voltage sensors are preferred in these converters.
A major reason for such development of these converters is
fast growth in microelectronic devices. Due to high volume requirements,
many manufacturers such as Unitrode, Analog Devices,
Siemens, Fairchild, National Semiconductor, etc., have
developed many dedicated ICs [6], [7], consequently, cost effective
and compact closed-loop control circuitry of these converters
with adequate speed and accuracy are obtained. There
are a number of ASICs [7] available for dedicated applications.
Moreover, due to the importance of enhancing the power quality,
several standards [1], [2] are imposed on the users and manufacturers
of these converters. A variety of instruments are available
to measure the performance of AC input in terms of powerfactor
(PF), crest factor (CF), total harmonic distortion (THD),
harmonic spectrum, displacement factor, VA, VAR, W, energy
consumed, at AC mains and voltage ripple, sag, surge, swell,
notch, etc. These measuring instruments are known as power analyzers,
power scopes, power monitors, spectrum analyzers, etc.