Switched-mode power supply

Abstract

The invention relates to a switched-mode power supply for supplying an output voltage (Uout) controlled to a target value (Us) to a load (S), which switched-mode power supply can be economically produced and is suitable for use in explosion-prone areas, comprising: a supply path, which comprises a switching controller (5) controlled by means of a driver (3), a galvanically separated transformer (7) connected after the switching controller (5), and an output circuit (9), which is connected after the transformer (7) and which comprises a rectifier (11) and to the output of which the load (S) canbe connected; and a feedback path, by means of which a signal, which is transmitted by means of a light source (13) and a light receiver (15) and which represents the output voltage (Uout), is fed tothe driver (3), on the basis of which signal the driver (3) controls the output voltage (Uout) to the target value (Us) by means of appropriate control of the switching controller (5), which switched-mode power supply is characterized in that the feedback path comprises a voltage controller (19), which controls a feed voltage that drops across the light source (13) to a fixed value lying below the target value (Us), and comprises a current controller (21), which controls a current flowing through the light source (13) to a current value corresponding to the output voltage (Uout).

Description

technical field [0001] The present invention relates to a switching power supply for supplying an output voltage controlled at a desired value to an electrical device, comprising: a supply path comprising a switching controller controlled via a driver, a galvanic isolation transformer connected behind the switching controller, and a rectifier connected after the transformer, the rectifier comprising an output circuit to which an electrical consumer can be connected; and a feedback path via which the driver is fed with a signal emitted via the light source and the light receiver and reflecting the output voltage , based on this signal, the driver controls the output voltage at the desired value via corresponding operation of the switch controller. Background technique [0002] This type of switching power supply is used, for example, to supply electronic devices installed in industrial measurement technology (e.g., electronic devices such as measuring devices, sensors, measur...

AI Technical Summary

Problems solved by technology

[0010] If one wants to apply such an optical signal transmitter in the feedback path of a switching power supply, then the power loss due to the current limiting resistor will reduce the efficiency of the switching power supply

Also, there is the issue of power loss being converted to heat

In this way, depending on the magnitude of the voltage dropped across the current limiting resistor and the current required by the light source, temperatures can develop in the area of ​​the current limiting resistor which would make it impossible to use the signal transmitter in explosion-hazardous areas

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