Electric power conversion systems – Current conversion – With starting arrangement
Reexamination Certificate
2002-07-22
2004-06-29
Sherry, Michael (Department: 2838)
Electric power conversion systems
Current conversion
With starting arrangement
C363S021100, C363S021180, C363S097000
Reexamination Certificate
active
06757183
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to a method for starting up a switched-mode power supply, as well as a switched-mode power supply having a starting circuit, in which the alternating voltage inputs of a bridge rectifier, at which an alternating voltage is adjacent, are connected with one another through a Y capacitor or a series circuit of two Y capacitors, in which a parallel circuit, made up of a first capacitor and a series circuit made up of the primary winding or coil of a first transformer and a first controllable switch, is connected to the direct voltage outputs of the bridge rectifier, whose control input is connected with the output of a pulse generator, and in which a series circuit of a first diode and a second capacitor is situated parallel to the secondary winding of the transformer.
The prior art includes providing a battery or an accumulator for starting up a switched-mode power supply.
However, the prior art method for starting up a switched-mode power supply has the disadvantage that the manufacturing costs are relatively high, and the endurance or life of the battery or of the accumulator is limited.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a method for starting up a switched-mode power supply, and switched-mode power supply having a starting circuit that overcome the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and that requires only a low technical outlay, has low manufacturing costs, and guarantees the endurance over a long period of time.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a method for starting up a switched-mode power supply, including the steps of providing a bridge rectifier having alternating voltage inputs, a control input, and direct voltage outputs, disposing an alternating voltage at the alternating voltage inputs of the bridge rectifier, connecting the alternating voltage inputs with one another through a Y capacitor circuit including one of a Y capacitor and a series circuit of two Y capacitors, providing a first transformer having a primary winding and a secondary winding, providing a first series circuit made up of the primary winding of the first transformer and a first controllable switch, connecting the control input of the bridge rectifier with an output of a pulse generator, connecting a parallel circuit made up of the first series circuit and a first capacitor to the direct voltage outputs of the bridge rectifier, connecting a second series circuit made of a first diode and a second capacitor in parallel to the secondary winding of the first transformer, transmitting energy collected by the Y capacitor circuit to the second capacitor, and driving the controllable switch by producing pulses with the pulse generator dependent on a voltage tapped at the second capacitor.
In accordance with another mode of the invention, the energy collected by the Y capacitors is transmitted to the second capacitor, and the pulse generator produces drive, trigger, or control pulses for the controllable switch dependent on a voltage that can be tapped at the second capacitor.
In accordance with a further mode of the invention, preferably, the pulse generator begins to produce drive pulses for the controllable switch only when the voltage at the second capacitor has exceeded a first threshold value. According to a specific embodiment of the invention, it is thereby provided that the voltage that can be tapped at the second capacitor is applied as a supply voltage to a supply voltage input of the pulse generator only when it has reached a first predeterminable minimum value in order to switch on the pulse generator.
In accordance with an added mode of the invention, preferably, the pulse generator produces no drive pulses when the voltage at the second capacitor has decreased below a second threshold value, whereby the second threshold value is smaller than the first threshold value. If the pulse generator is switched on, it receives current from the second capacitor, resulting in a lowering of the voltage that is adjacent over the second capacitor. Because the first threshold value, upon the reaching of which drive pulses are produced, is higher than the second threshold value, with no drive pulses being produced when the value falls below this second threshold value, the invention prevents the situation where the production of the drive pulses is immediately terminated again when there is a slight decrease of the voltage at the second capacitor at the beginning of the production of the drive pulses.
In accordance with an additional mode of the invention, the pulse generator has a supply voltage input, and the voltage tapped at the second capacitor is applied to the supply voltage input of the pulse generator only when the voltage tapped at the second capacitor reaches a first predeterminable minimum value.
In accordance with yet another mode of the invention, a control unit is connected to the pulse generator for controlling the pulse generator and the voltage tapped at the second capacitor is applied to the control unit only after a predeterminable time period after a switching on of the pulse generator.
In accordance with yet a further mode of the invention, there is provided a third series circuit made up of a second diode and a third capacitor, a second secondary winding of the first transformer is connected in parallel to the third series circuit, a voltage with the second secondary winding of the first transformer is produced at the third capacitor and the voltage tapped at the second capacitor is applied to the control unit when the voltage at the third capacitor reaches a second predeterminable minimum value.
With the objects of the invention in view, there is also provided a switched-mode power supply having a starting circuit, the power supply including a bridge rectifier having alternating voltage inputs to be connected to an alternating voltage, at least one direct voltage output, and a control input, a plurality of Y capacitors including two Y capacitors connected in series to form a first series circuit having a first common connection point, the alternating voltage inputs of the bridge rectifier connected with one another through one of the group consisting of one of the Y capacitors and the first series circuit, a pulse generator having an input and an output, a transformer having a primary winding and a secondary winding, a controllable switch connected in series to the primary winding to form a second series circuit, a first capacitor connected in parallel to the second series circuit to form a parallel circuit, the parallel circuit connected to the at least one direct voltage output of the bridge rectifier, the control input of the bridge rectifier connected to the output of the pulse generator, a first diode and a second capacitor connected in series to form a third series circuit having a second common connection point, the third series circuit connected in parallel to the secondary winding of the transformer, a second diode connecting the first common connection point to the second common connection point, and a signal supply device supplying a signal dependent on a voltage over the second capacitor to the input of the pulse generator.
In accordance with yet an added feature of the invention, the common connection point of the two Y capacitors is connected with the common connection point of the first diode and the second capacitor through a second diode, and a signal dependent on the voltage over the second capacitor is supplied to an input of the pulse generator, dependent on which the pulse generator produces drive pulses for the controllable switch.
In accordance with yet an additional feature of the invention, a system having a first threshold value detector and a second controllable switch is connected between the second capacitor and the pulse generator. The first threshold value detector is situated parallel to the tapping of the voltage at t
Feldtkeller Martin
Preller Peter
Infineon - Technologies AG
Laxton Gary L.
Sherry Michael
LandOfFree
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