Current sensor for non-contact current measurement

A circuit, having:

• an oscillator circuit with a magnetic core with at least one primary conductor which is magnetically coupled to the magnetic core, and with at least one secondary conductor which is magnetically coupled to the magnetic core, the oscillator circuit being designed to magnetize the magnetic core regularly in opposite directions up to a maximum value by controlling the at least one secondary conductor, and which is further designed to generate an oscillator signal which has a duty cycle which depends on the effective primary current;
• and
• a duty cycle amplifier circuit which is designed to increase a deviation of the duty cycle from a reference value which deviation is dependent on the effective primary current.

A circuit, having:

• an oscillator circuit with a magnetic core with at least one primary conductor which is magnetically coupled to the magnetic core, and with at least one secondary conductor which is magnetically coupled to the magnetic core, the oscillator circuit being designed to magnetize the magnetic core regularly in opposite directions up to a maximum value by controlling the at least one secondary conductor, and which is further designed to generate an oscillator signal which alternates from a first state to a second state, or vice versa, when the maximum value is reached;
• and an evaluation unit which is designed to determine a first measured value for an effective primary current which flows through the at least one primary conductor, based on the times that the oscillator signal dwells in the first and the second state, and, in parallel, to determine a second measured value for the effective primary current based on a secondary current flowing in the secondary conductor.

A method, comprising the steps of:

• alternating magnetizing a magnetic core to a maximum value in the positive and negative directions by controlling at least one secondary conductor which is magnetically coupled to the magnetic core;
• generating an oscillator signal which alternates between a first state and a second state, whereby the alternating magnetization processes are indicated;
• generating a modified oscillator signal with a duty cycle that deviates more from a reference value than a corresponding duty cycle of the oscillator signal and that depends on an effective primary current that flows through at least one primary conductor which is magnetically coupled to the magnetic core.