Voltage sensing device and associated method
A transformer circuit is disclosed that minimizes the temperature dependence of an output voltage. A first embodiment of the present invention includes a primary winding coupled to received a voltage to be sensed and a center-tapped secondary winding coupled at a center point to first voltage output terminal. The center-tapped secondary winding includes a first secondary winding and a second secondary winding, the secondary windings being coupled through a bridge circuit to a second voltage output terminal.
1. A voltage transformer circuit comprising:
a primary winding around a core of a first transformer;
a primary winding around a core of a second transformer, the first and second transformer primary windings being coupled to receive a voltage to be sensed;
a secondary winding around the core of the first transformer, the secondary winding of the first transformer being coupled to a first output terminal;
a secondary winding around the core of the second transformer, the secondary winding of the second transformer being coupled to the first output terminal; and
a bridge circuit coupled to the secondary windings of the first and second transformer and to a second output terminal, wherein said bridge circuit comprises a first resistor and a second resistor, said first resistor having a first and second end, said first end of the first resistor coupled to the secondary winding of said first transformer and said second resistor having a first and second end, said first end of the second resistor coupled to said secondary winding of said second transformer and said second end of the first resistor and said second end of the second resistor coupled to a second output terminal.
2. The voltage sensing and transformer device of claim 1 wherein a winding ratio of the primary windings to the secondary windings is greater than one.
3. The voltage sensing and transformer device of claim 1 wherein a winding ratio of the primary windings to the secondary windings is equal to one.
4. The voltage sensing and transformer device of claim 1 wherein a winding ratio of the primary windings to the secondary windings is less than one.
5. The voltage transformer circuit of claim 1 wherein:
a number of windings of the first transformer primary winding is equal to a number of windings on the second transformer primary winding; and
a number of windings of the first transformer secondary winding is equal to a number of windings on the second transformer secondary winding.