Electric power conversion systems – Current conversion – Including d.c.-a.c.-d.c. converter
Reexamination Certificate
2002-04-09
2003-07-01
Vu, Bao Q. (Department: 2838)
Electric power conversion systems
Current conversion
Including d.c.-a.c.-d.c. converter
C363S098000, C363S056020
Reexamination Certificate
active
06587359
ABSTRACT:
The invention relates to a DC—DC converter for converting a DC (direct current) input voltage into a plurality of DC output voltages, which converter may be operated in a normal operation mode and an energy-saving standby mode.
It is known, especially in the field of consumer electronics, to distinguish in relation to power supply between a normal operation mode during use of an appliance and a standby mode, wherein in standby mode the appliance does not perform its actual function but is merely ready to respond to an appropriate wake-up signal. Very much less power is required for the standby mode than for normal operation. Therefore, in such appliances a power supply unit with DC—DC converter is advantageously used, which supplies at least two output voltages which may be switched between a normal operation mode and a standby mode. The first output voltage serves to supply the main electronics of the appliance, while the other voltage merely supplies standby circuits. In standby mode, the first output voltage is conventionally reduced to zero or a very low value, while the second output voltage does not change or changes only insignificantly between normal operation mode and standby mode.
Given this background, it is an object of the present invention to provide a DC—DC converter and a power supply unit of the above-mentioned type, with which the losses arising during operation are smallest possible.
Said object is achieved by a DC—DC converter as claimed in claim 1 and a power supply unit as claimed in claim 9. Advantageous developments are included in the subclaims.
The DC—DC converter serves to convert a DC input voltage, which may be generated for example by rectification of an AC (alternating current) mains voltage, into a plurality of DC output voltages, of which typically one supplies the main electronics of an electronic appliance and another supplies the appliance's standby electronics. The converter comprises
a main circuit stage with switching elements for converting the DC input voltage at the input of the main circuit stage into a first AC voltage, which is passed via the outputs of the main circuit stage to two delivery nodes;
an auxiliary circuit stage with auxiliary switching elements and an auxiliary inductor for converting the DC input voltage at the inputs of the auxiliary circuit stage into a second AC voltage, which is passed via the outputs of the auxiliary circuit stage to the two above-mentioned delivery nodes;
a first resonant circuit for converting the AC voltages at the delivery nodes into a first AC output voltage, which serves to generate a first DC output voltage by means of a first rectifier;
a second resonant circuit for converting the AC voltages at the delivery nodes into a second AC output voltage, which serves to generate a second DC output voltage by means of a second rectifier and
a control circuit for activating the main circuit stage and the auxiliary circuit stage.
By appropriate activation of the main circuit stage or the auxiliary circuit stage via the control circuit, the DC input voltage at the circuit stages may be converted into a pulse-form AC voltage with a given frequency and a given mark-space ratio. This AC voltage is then fed to the two resonant circuits, which convert it into DC output voltages of appropriate magnitude depending on the position of its resonant frequency. The level of each DC output voltage may thus be varied via the frequency of the fed-in AC voltage, i.e. via the frequency with which the control circuit actuates the circuit stages.
The use of two circuit stages, the main circuit stage and the auxiliary circuit stage, has the advantage that these circuit stages may be optimally designed in each case for different operating modes of the DC—DC converter. In this way, it is possible in particular to design the different modes to be particularly energy efficient.
The auxiliary circuit stage is preferably designed for lower levels of power consumption than the main circuit stage. The auxiliary circuit stage may thus advantageously be used when the DC—DC converter is in an operating mode in which lower power levels are required on the output side. Such a mode of operation may correspond in particular to the standby mode of an electronic appliance.
According to a preferred development, the auxiliary circuit stage and the control circuit may be jointly constructed as an integrated circuit. This is possible in particular when the auxiliary circuit stage is intended for lower loads, such that it may be designed without difficulty as an integrated circuit.
The control circuit is advantageously so arranged or programmed that it may be operated as desired in normal operating mode or in standby mode. In normal operating mode, it activates the main circuit stage in such a way that the latter generates a first AC voltage in a first frequency range Df
1
, while, in standby mode, it activates the auxiliary circuit stage in such a way that the latter generates a second AC voltage in a second frequency range Df
2
. In normal operating mode and in standby mode respectively, the auxiliary circuit stage and the main circuit stage are then in each case unused or activated in such a way that they do not generate any output voltages. The output voltages generated from the first frequency range or the second frequency range respectively are converted, as explained above, via the resonant circuits and rectifiers into DC output voltages of varying magnitudes. One advantage in this situation is the fact that, in a standby mode with relatively low output-side power consumption, the necessary AC voltage may be generated on the input side of the resonant circuits by a suitably dimensioned (i.e. preferably thinner) circuit stage. In this way, the activation power and thus the current consumption of the DC—DC converter drops in stand-by operation.
For potential separation between the voltages at the delivery nodes and the outputs of the resonant circuits, a transformer may be provided which has a first primary winding associated with one of the two resonant circuits, a secondary winding associated with the first resonant circuit and a second secondary winding associated with the second resonant circuit. Furthermore, the transformer may comprise a second primary winding, which forms the auxiliary inductor of the auxiliary circuit stage. In this way, it is unnecessary to provide an additional separate component to constitute the auxiliary inductor.
The main circuit stage may alternatively take the form of a half-bridge circuit comprising two switching elements or a full bridge circuit comprising four switching elements. The auxiliary circuit stage preferably takes the form of a half-bridge circuit including two switching elements.
In addition to the first resonant circuit, the DC—DC converter may include one or more further output circuits, which provide further main outputs. In the further output circuits, the AC voltages at the delivery nodes are converted into AC output voltages, which serve to generate the further DC output voltages.
The invention further relates to a power supply unit which is characterized in that it includes a DC—DC converter of the above-described type. Such a power supply unit is suitable, in particularly current-saving manner, for normal current supply of an electronic appliance in normal operating mode and for supplying the appliance with reduced power in standby mode.
REFERENCES:
patent: 6246599 (2001-06-01), Jang et al.
patent: 6418038 (2002-07-01), Takahama et al.
patent: 6424543 (2002-07-01), Zhang et al.
Deppe Carsten
Raets Hubert
Halajian Dicran
Koninklijke Philips Electronics , N.V.
Vu Bao Q.
LandOfFree
DC-DC converter with switchable control mode does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with DC-DC converter with switchable control mode, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and DC-DC converter with switchable control mode will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3022757