Electric power conversion systems – Current conversion – Including d.c.-a.c.-d.c. converter
Reexamination Certificate
1999-10-04
2001-01-09
Wong, Peter S. (Department: 2838)
Electric power conversion systems
Current conversion
Including d.c.-a.c.-d.c. converter
C363S098000, C323S222000
Reexamination Certificate
active
06172885
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a switched-mode power supply with mains current consumption regulation which, inter alia, has the following features:
(a) at least one power factor controller, including:
(a1) a power regulating configuration for regulating the mains current consumption, and a rectifier configuration;
(a2) two input connections at which a mains voltage can be input into the switched-mode power supply; and
(a3) two output terminals at which a bus voltage can be tapped off;
(b) a switched-mode regulator which is connected to the output terminals of the rectifier configuration and at whose output terminals an output voltage can be tapped off; and
(c) a load which is connected downstream of the switched-mode regulator and is disposed between its output terminals.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a switched-mode power supply with mains current consumption regulation which overcomes the above-mentioned disadvantages of the prior art devices of this general type.
With the foregoing and other objects in view there is provided, in accordance with the invention, a switched-mode power supply, including:
at least one power factor controller having a power regulating configuration for regulating a sinusoidal mains current consumption, a rectifier configuration connected to the power regulating configuration, two input connections at which a mains voltage can be input into the at least one power factor controller, and two output terminals at which a bus voltage can be tapped off and being concurrently output terminals of the rectifier configuration;
a switched-mode regulator connected to the output terminals of the rectifier configuration and having regulator output terminals at which an output voltage can be tapped off;
a load connected downstream of the switched-mode regulator and disposed between the regulator output terminals;
a first measurement configuration having an output outputting a first regulating signal dependent on the bus voltage;
a feed forward control having a first feedback path with an integrator configuration for feeding back the first regulating signal to the power regulating configuration;
a second feedback path having an output; and
a second measurement configuration connected to the regulator output terminals and if a power consumption of the load changes, the second measurement configuration produces a second regulating signal which can be input into the power regulating configuration via the second feedback path.
The object of such known switched-mode power supplies is to provide a DC voltage that is as constant as possible at the output terminals of the switched-mode regulator, with a mains power consumption which is as sinusoidal as possible. The requirement for such switched-mode power supplies to have a sinusoidal mains current consumption results from the European Commission Order according to which power supplies, for example computers, with a power consumption of more than 75 W, must ensure a mains current consumption which is as sinusoidal as possible.
The object of the power regulating configuration is, on the one hand, to produce a sinusoidal mains power consumption at its output terminals and, on the other hand, to regulate the power emitted to the rectifier configuration via the output terminals of the power regulating configuration such that a bus voltage which is as constant as possible, even when the load on the output terminals of the switched-mode regulator fluctuates, at the output terminals of the rectifier configuration. The switched-mode regulator connected downstream of the rectifier configuration uses the bus voltage to produce an output voltage, which is transformed down, is isolated from the mains and is resistant to short circuits, for loads connected to its output terminals. The object of the first measurement configuration is to provide a first bus voltage signal which is dependent on the bus voltage and is fed back via a first feedback path to the power regulating configuration, in order to regulate the emitted power as a function of the bus voltage. The first feedback path in such switched-mode power supplies normally includes an integrator having a long time constant, in order to eliminate the influences of unavoidable residual ripple of the bus voltage on the regulation of the power emitted from the power regulating configuration.
The disadvantage of such switched-mode power supplies is that the bus voltage rises sharply when the load on the output terminals of the switched-mode regulator falls, before the power regulating configuration (governed by the integration of the bus voltage signal which is dependent on the bus voltage) regulates the emitted power down. Such switched-mode power supplies therefore require over-voltage disconnection, which switches off the power regulating configuration when the bus voltage exceeds a nominal value by a predetermined amount, in order to protect those components connected to the output terminals of the rectifier configuration from being destroyed. Therefore, in some circumstances, the power regulating configuration is switched off for several seconds, which is disadvantageous particularly when the power regulating configuration is supplying an integrated circuit which, for example, includes the control logic for the power regulating configuration or the switched-mode regulator.
U.S. Pat. No. 5,515,257 discloses an AC/DC converter which has a power factor controller with a power regulating configuration for regulating the mains current consumption, a rectifier device as well as a switched-mode regulator. The switched-mode regulator is connected to the rectifier configuration. Furthermore, a load across which an output voltage can be tapped off can be connected to its output terminals. The output voltage is tapped off from a measurement configuration and is supplied to a pulse-width modulator that produces a regulating signal and controls the switched-mode regulator. Furthermore, the regulating signal is supplied, after weighting in a frequency divider, to the power factor controller in order to keep the voltage supplied to the switched-mode regulator approximately constant. In consequence, the AC/DC converter can be operated over a wide input voltage range.
The object of the present invention is thus to provide a switched-mode power supply having a sinusoidal mains current consumption and a DC voltage which is as independent as possible of the load across the output terminals of the switched-mode regulator, in which the power regulating configuration reacts virtually without any delay to load changes at the output of the switched-mode regulator.
In addition to a first bus voltage signal which is dependent on the bus voltage and is fed back, after integration, to the power regulating configuration, a second regulating signal, which is dependent on the output voltage, is also fed back in the switched-mode power supply according to the invention via a second feedback path to the power regulating configuration, with no integrator being required in the second feedback path. The power regulating configuration can thus react virtually without any time delay to load changes at the output terminals of the switched-mode regulator, by varying the power emitted to the rectifier configuration.
The power regulating configuration advantageously has a power switch that is disposed in parallel with the output terminals of the power regulating configuration and is controlled by drive pulses. An open switch results in that current flows from the power regulating configuration to the rectifier configuration, while a closed power switch short-circuits the output of the power regulating configuration, as a result of which no current flows in the direction of the rectifier configuration and, in consequence, no power is emitted to it. The power emitted to the rectifier configuration can thus be regulated, inter alia, as a function of the duration of the drive pulses.
A further embodiment provides for the
Greenberg Laurence A.
Infineon - Technologies AG
Lerner Herbert L.
Patel Rajnikant B.
Stemer Werner H.
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