US 2003/0141874 A1 · Circuit configuration and method for measuring and limiting currents

Abstract

A circuit configuration and a method for determining a current drawn from a mains by a converter through a dc voltage intermediate circuit, replaces a required pulse-resistant input current measuring resistor with a conductor track of the circuit configuration itself. Since the input current drawn from the mains by the dc voltage intermediate circuit is on average equal to the output current delivered to the converter, the present resistance of the conductor track is given by the resistance of the measuring resistor downstream of the dc voltage intermediate circuit, weighted with the quotient of the input and output voltage drops. In that way, the mains current and therewith the power factor can be influenced by way of a current limiter without requiring an expensive pulse-resistant special resistor for mains current measurement.

Claims8

Dependent claims

A circuit configuration for ascertaining a current, the circuit configuration comprising:

a dc voltage intermediate circuit;
a converter receiving the current to be ascertained, from said dc voltage intermediate circuit;
an output current measuring resistor downstream of said dc voltage intermediate circuit;
and
an input current measuring resistor upstream of said dc voltage intermediate circuit, said input current measuring resistor being a conductor track of the circuit configuration.

2 more elements

A method of ascertaining an input current, which comprises:

providing a dc voltage intermediate circuit;
providing a converter receiving the input current to be ascertained, from the dc voltage intermediate circuit;
providing an input current measuring resistor upstream of the dc voltage intermediate circuit;
providing a known output current measuring resistor downstream of the dc voltage intermediate circuit, defining an output voltage drop across the output current measuring resistor;
determining an input current upstream of the dc voltage intermediate circuit as a quotient of an input voltage drop across the input current measuring resistor and a magnitude of the input current measuring resistor;
and
determining the magnitude of the input current measuring resistor by evaluating the known output current measuring resistor with a quotient of a currently measured period mean value of the input voltage drop and the output voltage drop.

4 more elements

Dependencies are inferred from the claim text.

Circuit configuration and method for measuring and limiting currents

Life of this patent

Circuit configuration and method for measuring and limiting currents

Life of this patent

Abstract

Claims8