Current measurement circuit

A control arrangement system for a power converter having power switches, comprising a current measurement circuit including:

• a) a first current sensing circuit for sensing a first bidirectional current representative of a current through a first power switch of the power converter, the first current sensing circuit being adapted to provide a first sensing signal indicative of the first bidirectional current;
• b) a second current sensing circuit for sensing a second bidirectional current representative of a current through a second power switch of the power converter, the second current sensing circuit being adapted to provide a second sensing signal indicative of the second bidirectional current;
• and
• c) a switching circuit being adapted to provide a first measurement signal based on the first sensing signal, the second sensing signal and a polarity signal representative of a polarity of an input voltage of the power converter, wherein the first measurement signal is indicative of the first bidirectional current during a first time interval starting at a zero-crossing of the first bidirectional current and ending at switching off of the first power switch, and indicative of the second bidirectional current during a third time interval starting at a zero-crossing of the second bidirectional current and ending at switching off of the second power switch, and a power factor controller for controlling a switching of the power switches of the power converter, wherein during other time intervals when the first sensing signal or the second sensing signal have another direction different from the first bidirectional current or second bidirectional current, the first sensing signal or the second sensing signal will be redirected such that the secondary winding of the current transformer is shorted.

An AC-DC Power converter having power switches comprising:

• a current measurement circuit including:
• a) a first current sensing circuit for sensing a first bidirectional current representative of a current through a first power switch of the power converter, the first current sensing circuit being adapted to provide a first sensing signal indicative of the first bidirectional current;
• b) a second current sensing circuit for sensing a second bidirectional current representative of a current through a second power switch of the power converter, the second current sensing circuit being adapted to provide a second sensing signal indicative of the second bidirectional current;
• and
• c) a switching circuit being adapted to provide a first measurement signal based on the first sensing signal, the second sensing signal and a polarity signal representative of a polarity of an input voltage of the power converter, wherein the first measurement signal is indicative of the first bidirectional current during a first time interval starting at a zero-crossing of the first bidirectional current and ending at switching off of the first power switch, and indicative of the second bidirectional current during a third time interval starting at a zero-crossing of the second bidirectional current and ending at switching off of the second power switch, wherein during other time intervals when the first sensing signal or the second sensing signal have another direction different from the first bidirectional current or second bidirectional current, the first sensing signal or the second sensing signal will be redirected such that the secondary winding of the current transformer is shorted, and
• a triangular current mode power factor controller for controlling a switching of the power switches of the AC-DC power converter.

Method for providing a measurement signal for a controller for controlling a switching of power switches of a power converter, comprising the steps of

• a) providing a first sensing signal by sensing a first bidirectional current representative of a current through a first power switch of the power converter;
• b) providing a second sensing signal by sensing a second bidirectional current representative of a current through a second power switch of the power converter;
• and
• c) providing a first measurement signal based on the first sensing signal, the second sensing signal and a polarity signal representative of a polarity of an input voltage of the power converter, wherein the first measurement signal is indicative of the first bidirectional current during a first time interval starting at a zero-crossing of the first bidirectional current and ending at switching off of the first power switch, and indicative of the second bidirectional current during a third time interval starting at a zero-crossing of the second bidirectional current and ending at switching off of the second power switch, wherein during other time intervals when the first sensing signal or the second sensing signal have another direction different from the first bidirectional current or second bidirectional current, the first sensing signal or the second sensing signal will be redirected such that the secondary winding of the current transformer is shorted.