Electric power conversion systems – Current conversion – Including automatic or integral protection means
Patent
1996-04-30
1998-03-17
Wong, Peter S.
Electric power conversion systems
Current conversion
Including automatic or integral protection means
363 21, 363126, H02H 7122, H02M 3335, H02M 700
Patent
active
057294470
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a switched-mode power supply comprising a transformer, source in periodically recurring time intervals, and the transformer, and to be applied to a storage inductance and a load impedance by means of a rectifier arrangement.
The invention relates particularly to a switched-mode power supply of this type for the generation of one or more d.c. output voltages which are electrically isolated from an input voltage.
2. Description of the Related Art
Such circuit arrangements can be realized by means of an active circuit device. The different variants, such as forward convertors and flyback converters are known from the book "Schaltnetzteile-Grundlagen, Entwurf, Schaltungsbeispiele" by J. Wustehube et al (Expert Verlag). In these known circuit arrangements, a transfer of energy from the primary side (input source) to the secondary side (power-consuming devices, load) is effected only during the on-time of the active circuit device (forward converter) or only during the off-time of the active circuit device (flyback converter). An essential drawback of this circuit arrangement is the inefficient use of the magnetic devices.
A circuit arrangement which allows an energy transfer during the on-time and off-time of the active circuit device is known from the article "A Dual Mode Forward/Flyback Converter" by J. N. Park and T. R. Zaloum (PESC 1982, 3). The circuit arrangement proposed therein requires two separate secondary windings for each output voltage required. This is a serious drawback, particularly in the case that a small winding space is available, or a large number of output voltages are required.
U.S. Pat. No. 3,740,639 discloses a switching regulator with a switch whose state of conduction is controlled in dependence on the voltage across a load. This switching regulator comprises a transformer whose primary winding is connected in a circuit with the switch. A rectifier and an inductive storage element are connected in a circuit with the secondary winding, a diode being included between one end of the secondary winding and one terminal of the load. This diode serves to transfer energy from the secondary winding to the load in the off-times of the switch.
However, it has been found that with the switching regulator in accordance with U.S. Pat. No. 3,740,639 an optimum energy transfer to the load is not possible depending on the dimensioning of the transformer and the inductive power storage element, and on the magnitude and form of the currents in the switching regulator.
It is an object of the invention to obtain the advantage of the energy transfer during the on-time and the off-time of the active switching element by means of only one secondary winding for each output voltage required and an optimum energy transfer, i.e., an improved efficiency, independently of the dimensioning of the elements of the switching regulator.
According to the invention this object is achieved in a switched-mode power supply of the type defined in the opening paragraph, in that the rectifier arrangement comprises three current paths, of which and to the load impedance during said time intervals, secondary winding and the load impedance, and the load impedance, the demagnetizations of the transformer and the storage inductance are effected outside said time intervals and, simultaneously and are not influenced by one another.
Thus, in accordance with the invention, starting from the secondary winding, two separate current paths (power transmission paths) are obtained by means of rectifier elements (diodes) in order to transmit energy to the output of the switched-mode power supply and hence, to the load impedance during the on-time and off-time of an active switching device via which the electric power is applied to the primary winding in the periodically recurring time intervals. In the first current path (power transmission path) available for the energy transfer during the on-time of the active switching device, i.e., during the above-mentioned
REFERENCES:
patent: 3740639 (1973-06-01), Easter
Albach Manfred
Durbaum Thomas
Goodman Edward W.
Patel Rajnikant B.
U.S. Philips Corporation
Wong Peter S.
LandOfFree
Switched-mode power supply does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Switched-mode power supply, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Switched-mode power supply will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-963756