Electric power conversion systems – Current conversion – Including d.c.-a.c.-d.c. converter
Patent
1993-12-17
1996-09-24
Wong, Peter S.
Electric power conversion systems
Current conversion
Including d.c.-a.c.-d.c. converter
363101, 363134, H02M 3337
Patent
active
055596843
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a switching regulator, comprising a push-pull converter with a series-connected buck or boost regulator. A switching regulator of this kind with a series-connected buck regulator is known from Watkins Johnson Co., Palo Alto, USA, Tech-Notes "Design of Power Converters for Space TWTA's", pages 1 to 13, or from German Patent Publication DE 29 41 009 C2.
Switching regulators of this type are employed when greatly varying input voltages must be processed, such as in satellite power supplies. As a rule, the buck regulator is pulse-width modulated as a function of the output voltage of the switching regulator. The downstream-connected push-pull converter is operated either with push-pull pulses of constant lengths or also with pulse-width modulated pulses.
A switching regulator in the form of a boost or buck regulator having an auto-transformer and with a downstream-connected push-pull regulator is known from British Patent GB-PS 1,172,501.
It is known from German Patent Publication DE 29 41 009 C2 to series-connect a series switching regulator in the form of a boost/or buck regulator to a conventional push-pull regulator, in particular for the purpose of processing greatly varying input voltages, for example with satellite power supplies. There, too, the series switching regulator is pulse-width modulated as a function of the output voltage of the switching regulator.
SUMMARY OF THE INVENTION
It is the object of the invention to embody the switching regulator of the previously mentioned type in such a way that a high degree of efficiency can be achieved. This object is attained by the characteristics of claim 1. The dependent claims disclose advantageous embodiments of the invention. Although it is known from U.S. Pat. No. 4,959,765 or from the Siemens Journal 48 (1974), Issue 11, pages 840 to 846, to complement a push-pull regulator to form a resonance converter by connecting a resonance capacitor in order to improve the efficiency of a push-pull regulator, the resonance converters therein disclosed are not easily suited for operation with a series-connected buck regulator or boost regulator. To reduce switching losses in the push-pull regulator known from EP 77 958 B1, the push-pull regulators are operated with a blackout time of such a duration that during this time the push-pull regulator as a resonance structure can automatically reverse by means of its inherent resonance excitation.
The switching regulator in accordance with the invention has the advantage that it is possible to select the capacity of the corresponding resonance converter to be higher than in conventional resonance or quasi-resonance converters. Sufficient time is available for recharging a resonance capacitor, namely in each case the time while the respective push-pull switch is open and the blackout time. It is possible to operate the resonance converter with a boost or buck regulator meaningfully as a pre-regulator only on the basis of this realization. The transformer of the push-pull converter is better utilized than with other comparable resonance converters, i.e. with the same output it is possible to reduce the structural size, which is of particular advantage in the employment in satellites. The regulation of the buck regulator or the boost regulator is very dependable, because the regulating criteria are derived from separate branches of the push-pull converter. Interference signals (ripples) are greatly suppressed by adding the voltages at the resonance capacitors for regulating the buck regulator in accordance with claim 6.
BRIEF DESCRIPTION OF THE DRAWING
An exemplary embodiment of the invention will be described in greater detail by means of the drawings. Shown are in
FIG. 1 a principal circuit diagram of a switching regulator in accordance with the invention,
FIGS. 2A, 2B and 2C courses over time of selected signals for the switching regulator in accordance with FIG. 1,
FIG. 3 a replacement circuit diagram of the push-pull converter for one of the push-pull branche
REFERENCES:
patent: 4443840 (1984-04-01), Geissler et al.
patent: 4937725 (1990-06-01), Dhyanchand et al.
patent: 4980813 (1990-12-01), Wells
patent: 5001413 (1991-03-01), Ohms
patent: 5353212 (1994-10-01), Loftus, Jr.
patent: 5438500 (1995-08-01), Ohms
Ohms Franz
Rupright Heike
Ant Nachrinctentechnik GmbH
Berhane Adolf
Wong Peter S.
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