Closed-loop fluxgate current sensor
First Claim
1. Electrical current sensor comprising a measuring circuit and an inductor for measuring a primary current Ip flowing in a primary conductor over a current range from a minimum specified current amplitude to a maximum specified current amplitude, the inductor comprising a saturable magnetic core made of a highly permeable magnetic material and a secondary coil for carrying an alternating excitation i configured to alternatingly saturate the magnetic core, said secondary coil being connected to the measuring circuit, wherein the measuring circuit is configured to supply a positive or negative voltage to the inductor, to switch off said positive or negative voltage when a condition signalling saturation is reached, to measure a time to saturation t1 in one direction and a time to saturation t2 in another direction of the magnetic core and determine therefrom a value of the primary current for primary currents having an amplitude in a first portion of the current range from the minimum specified current to a transition amplitude, the measuring circuit being further configured for evaluating an average value of said alternating excitation current i during phases when a voltage is supplied to the inductor and before the saturation condition is reached, and determining therefrom a value of the primary current for primary currents having an amplitude in a second portion of the current range from the transition amplitude to the maximum specified current amplitude.
3 Assignments
0 Petitions
Accused Products
Abstract
Electrical current sensor comprising a measuring circuit (6) and an inductor (4) for measuring a primary current IP flowing in a primary conductor (2), the inductor comprising a saturable magnetic core (10) made of a highly permeable magnetic material and a secondary coil (12) for carrying an alternating excitation i configured to alternatingly saturate the magnetic core, the coil being connected to the measuring circuit. The measuring circuit is configured to supply a positive or negative voltage to the inductor, to switch off the voltage when a condition signalling saturation is reached, to measure the time to saturation t1 in one direction and the time to saturation t2 in the other direction of the magnetic core and determine therefrom a value of the primary current for small current amplitudes, the measuring circuit being further configured for evaluating the average value of the excitation current i and determining therefrom the value of the primary current for large currents.
9 Citations
14 Claims
- 1. Electrical current sensor comprising a measuring circuit and an inductor for measuring a primary current Ip flowing in a primary conductor over a current range from a minimum specified current amplitude to a maximum specified current amplitude, the inductor comprising a saturable magnetic core made of a highly permeable magnetic material and a secondary coil for carrying an alternating excitation i configured to alternatingly saturate the magnetic core, said secondary coil being connected to the measuring circuit, wherein the measuring circuit is configured to supply a positive or negative voltage to the inductor, to switch off said positive or negative voltage when a condition signalling saturation is reached, to measure a time to saturation t1 in one direction and a time to saturation t2 in another direction of the magnetic core and determine therefrom a value of the primary current for primary currents having an amplitude in a first portion of the current range from the minimum specified current to a transition amplitude, the measuring circuit being further configured for evaluating an average value of said alternating excitation current i during phases when a voltage is supplied to the inductor and before the saturation condition is reached, and determining therefrom a value of the primary current for primary currents having an amplitude in a second portion of the current range from the transition amplitude to the maximum specified current amplitude.
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7. A method of measuring an electrical current flowing in a primary conductor over a current range from a minimum specified current amplitude to a maximum specified current amplitude comprising:
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providing a current sensor including a measuring circuit and an inductor, the inductor comprising a secondary coil wound around a saturable magnetic core, applying an excitation voltage to the secondary coil to alternatingly saturate the magnetic core, evaluating an average value of an alternating excitation current during phases when the excitation voltage is applied for measurement of large primary currents, and measuring times to saturation t1, t2 of the magnetic core of a negative, respectively positive signal of the alternating excitation current and for small currents determining a primary current based on the relationship of alternating saturation times t1, t2, where small primary currents have amplitudes in a first portion of the current range from the minimum specified current Imin to a transition or intermediate amplitude, and large primary currents have an amplitude in a second portion of the current range from the transition amplitude to the maximum specified current amplitude Imax. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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Specification