Method and apparatus for measuring AC voltages

• US 9,279,832 B2
• Filed: 10/01/2012
• Issued: 03/08/2016
• Est. Priority Date: 03/26/2008
• Status: Active Grant

• Current Assignee: Enphase Energy Incorporated
• Original Assignee: Enphase Energy Incorporated
• Inventors: Fornage, Martin
• Primary Examiner(s): Nguyen, Hoai-An D
• Application Number:
  US13/632,601
• Publication Number:
  US 20130027025A1
• Time in Patent Office: 1,254 Days
• Field of Search: 324/76.11, 324/522, 702/1, 702/57, 702/64, 340/663, 340/662, 340/660
• US Class Current: 1/1
• CPC Class Codes: G01R 1/203 Resistors used for electric measuring, e.g. decade resistors standards, resistors for comparators, series resistors, shunts resistors in general H01C; microwave or radiowave terminations H01P1/26; coupling devices H01R
• CPC Class Codes: G01R 15/22 using light-emitting devices, e.g. LED, optocouplers G01R31/31901 takes precedence
• CPC Class Codes: G01R 19/0084 measuring voltage only all subgroups of G01R19/00 take precedence
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence
• CPC Class Codes: G01R 19/2503 for measuring voltage only, e.g. digital volt meters (DVM's) G01R19/2506 - G01R19/257 take precedence

Abstract

A method and apparatus for measuring an AC voltage. In one embodiment, the apparatus includes an AC voltage monitoring circuit, coupled to at least one AC line, for producing a digital representation of a voltage on the at least one AC line, processing the digital representation to create a data stream containing information regarding the digital representation, and coupling the data stream through an isolation device to form an output signal.

Claims

1. An apparatus for monitoring voltage, comprising:

an AC voltage monitoring circuit, coupled to at least one AC line, for continuously producing a digital representation of a voltage on the at least one AC line, wherein the digital representation is a representation of instantaneous voltage on the at least one AC line;

processing the digital representation to create a data stream containing information regarding the digital representation; and

coupling the data stream through an isolation device to form an output signal.

2. The apparatus of claim 1, wherein the AC voltage monitoring circuit comprises a scaling circuit comprised of resistors to scale the voltage for measurement.

3. The apparatus of claim 1, wherein the AC voltage monitoring circuit is powered by a capacitive divider coupled to the at least one AC line.

4. The apparatus of claim 1, wherein the AC voltage monitoring circuit comprises a universal asynchronous receiver-transmitter (UART) for generating the data stream and coupling the data stream to the isolation device.

5. The apparatus of claim 1, wherein the digital representation is produced by sequential digitization of input signals.

6. The apparatus of claim 1, wherein the isolation device is a solid state electrical isolation device.

7. The apparatus of claim 6, wherein the solid state electrical isolation device is an optocoupler.

8. The apparatus of claim 1, wherein the at least one AC line transmits a single-phase AC voltage.

9. The apparatus of claim 1, wherein the AC voltage monitoring circuit is coupled to an inverter and transmits the output signal to the inverter.

10. The apparatus of claim 1, wherein the AC voltage monitoring circuit is coupled to an uninterruptable power supply (UPS) and transmits the output signal to the UPS.