Current sensor
First Claim
1. Apparatus for sensing currents comprising:
- sensing means including first and second transformers each having a primary winding connected in series and defining a loop for carrying a current to be sensed and each having a secondary winding which is electrically isolated from the primary winding and a magnetic core for magnetically coupling the primary winding with the secondary winding;
means for feeding the secondary winding of said first transformer with a cyclic magnetization current to cyclically drive the magnetic core of said first transformer into saturation;
separating means for separating said cyclic magnetization current from a first sensed current component induced from said primary winding into the secondary winding of said first transformer;
processing means for processing said first sensed current component together with a second sensed current component induced from said primary winding into the secondary winding of said second transformer to provide an output signal substantially proportional to the current to be sensed.
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Accused Products
Abstract
A current sensing apparatus includes a first transformer having a core which is cyclically driven into forward and reverse saturation, and a second transformer having a separate core. The sensing apparatus includes circuitry for separating the sensed current component from the magnetizing current in the secondary winding of the first transformer. The apparatus may also include correction circuitry to cancel the effects of ripple current on the output due to both the magnetization current and errors due to the presence of the ripple cancellation circuitry itself. The present sensing apparatus provides electrical isolation between the primary circuit and the sensing circuit, has wide bandwidth, and is sensitive to temperature, temperature gradient, mechanical forces, aging (creep) and noise.
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Citations
8 Claims
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1. Apparatus for sensing currents comprising:
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sensing means including first and second transformers each having a primary winding connected in series and defining a loop for carrying a current to be sensed and each having a secondary winding which is electrically isolated from the primary winding and a magnetic core for magnetically coupling the primary winding with the secondary winding; means for feeding the secondary winding of said first transformer with a cyclic magnetization current to cyclically drive the magnetic core of said first transformer into saturation; separating means for separating said cyclic magnetization current from a first sensed current component induced from said primary winding into the secondary winding of said first transformer; processing means for processing said first sensed current component together with a second sensed current component induced from said primary winding into the secondary winding of said second transformer to provide an output signal substantially proportional to the current to be sensed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification