SMART METER VOLTAGE SENSING USING OPTICALLY COUPLED ISOLATORS
First Claim
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1. A method of sensing voltage within a smart meter comprising:
- coupling a voltage divider to a high voltage portion of the smart meter; and
optically coupling the high voltage portion to a low voltage portion;
wherein the optical coupling is provided by an infrared (IR) emitting diode on the high voltage portion and an optical transistor on the low voltage portion;
wherein the IR emitting diode and the optical transistor comprises a optically coupled isolator;
wherein a third resistor (RD) coupled to the IR emitting diode provides a bias condition to the IR emitting diode;
wherein the third resistor (RD) is determined by the equation
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Abstract
A transformer-less method and system for voltage and current sensing using voltage drops across resistors is disclosed. Using optically coupled isolators, the sensed voltages in the high voltage power lines are optically coupled and electrically isolated to the low voltage circuits. The circuit designs for voltage and current sensing'"'"'s and electrical isolation are disclosed.
2 Citations
14 Claims
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1. A method of sensing voltage within a smart meter comprising:
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coupling a voltage divider to a high voltage portion of the smart meter; and optically coupling the high voltage portion to a low voltage portion;
wherein the optical coupling is provided by an infrared (IR) emitting diode on the high voltage portion and an optical transistor on the low voltage portion;
wherein the IR emitting diode and the optical transistor comprises a optically coupled isolator;wherein a third resistor (RD) coupled to the IR emitting diode provides a bias condition to the IR emitting diode;
wherein the third resistor (RD) is determined by the equation - View Dependent Claims (2, 3, 4, 5, 6, 7)
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9. The system of claim 8, wherein the IR emitting diode is biased in a forward conduction region to maximize a change in current with respect to a change of the applied forward voltage.
- 10. The system of claim 8, wherein the IR emitting diode operates at a forward conduction region of a current-voltage characteristic of the IR emitting diode with large gain to maximize sensitivity of the optically coupled isolator while minimizing current consumption.
- 13. The system of claim 8, whereas the optical transistor is in an open collector configuration.
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