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A new low-distorting three-phase diode rectifier employing optimum ripple power control
Abstract
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A simple scheme is proposed for offline unity power factor
rectification for high-frequency AC buses (20 kHz). A bandpass filter of
the series-resonant type, centered at the line frequency, is inserted
between the line and the full-wave rectified load. The Q = Z
0/ R L formed by the load and the
characteristic impedance of the tank circuit determines the power
factor, the boundary between continuous and discontinuous conduction
modes, the peak stresses, and the transient response of the rectifier.
It is shown that for Q >2/π the rectifier operates in
continuous conduction mode and the output voltage is independent of the
load. Also, it is shown that for Q >2 the line current is
nearly sinusoidal with less than 5% third-harmonic distortion and the
power factor is essentially unity. An increase in Q causes an
increase in the peak voltages of the tank circuit and a slower transient
response of the rectifier circuit. The DC, small-signal, and transient
analyses of the rectifier circuit are carried out, and the results are
in good agreement with simulation and experimental results
Two new schemes of low-distorting three-phase diode-bridge rectifiers with capacitive smoothing of the output voltage are proposed, analyzed, and verified. The harmonic distortion reduction technique proposed is based on optimum injection of the third-, sixth-, and ninth-harmonic ripple currents. To improve the efficiency, the third-harmonic ripple power is re-rectified using a low-power auxiliary AC-DC converter. Function of the sixth-harmonic current branch is, firstly, to compensate inductive current component of the smoothing inductors and, secondly, to induce a small active sixth-harmonic current component that enables to reduce the total harmonic distortion THD about 2%. The ninth-harmonic current branch enables a further reduction of the THD about 1.5%. In proposed schemes, low values of the THD hold in wide range of the load and supply-voltage variation
Efficient two-stage power factor correctors for three-phase diode
rectifiers providing a power factor PF⩾0.995 are proposed, analysed
and verified. The technique proposed is based on ripple-power conversion
into an additional quantity of the DC output power. The new schemes
contain a series-resonant third-harmonic filter and a low-power
auxiliary AC-DC power converter for optimum re-rectification of the
ripple power
This paper presents a description and analysis of a new AC/DC
converter topology for use in the high-frequency power distribution
system in Space Station Freedom. Steady-state analysis of the converter
is provided, the performance characteristics presented, and transient
behavior studied. The proposed converter has close-to-unity rated power
factor (greater than 0.98), low total harmonic distortion in input
current (less than 5%), and high conversion efficiency (greater than
96%). Finally, to verify the proof of-concept, a bread-board converter
was built
In this paper, a new approach to improve power factor and reduce harmonics generated by a three-phase diode rectifier type utility interface is proposed. The proposed approach is passive and consists of a novel interconnection of a star / delta transformer between the ac and dc sides of the diode rectifier topology (see Fig, 1). This novel interconnection, in combination with the 120° conduction intervals of each diode, is shown to generate a circulating third harmonic current between the ac and dc side of the rectifier bridge. The circulating third harmonic current between the ac and dc side of the rectifier bridge. The circulating third harmonic current is then shown to drastically improve the performance of the diode rectifier type interface. The resulting input current is near sinusoidal in shape with significant reduction in line current harmonics. The proposed system can be viewed as a cost-effective retrofit to the existing diode rectifier utility interface applications. Analysis and design of the proposed approach are examined in per-unit quantities. A suitable design example illustrates the sizing of the necessary passive components. Selected results are verified experimentally on a laboratory prototype system.
Harmonic distortion in power systems is growing due to the
popularity of switch-mode power electronic equipment. This equipment has
recognized advantages, such as reducing weight and improving control and
efficiency in power converters and supplies. A disadvantage of
switch-mode power converters is that their lowest-cost circuit may
burden the power system with harmonic loading. Methods to reduce this
distortion are recognized, but economic incentives are yet to be
realized. Standardization is the most effective means to influence
equipment design and to control distortion in power systems. The authors
compare the major European and American standards, as well as some of
the electronic equipment design changes that are supposed to limit
harmonics
An improved high power factor three-phase diode rectifier employing zero-sequence inductance and ripple power rerectification
- T Sakkos
- V Sarv
- V Bolgov
A novel low-harmonic three-phase diode rectifier type utility interface applying passive resistance emulation
- Ž Janda
- P Pejović