High Power DC Kilowatt Hour Meter

• US 20110238341A1
• Filed: 03/25/2011
• Published: 09/29/2011
• Est. Priority Date: 03/25/2010
• Status: Abandoned Application

• Current Assignee: Board of Regents Nevada System of Higher Education (State of Nevada)
• Original Assignee: Board of Regents Nevada System of Higher Education (State of Nevada)
• Inventors: McPherson, Dana, Etezadi-Amoli, Mehdi
• Application Number:
  US13/072,111
• Publication Number:
  US 20110238341A1
• Time in Patent Office: Days
• US Class Current: 702/61
• CPC Class Codes: B01D 2253/108 Zeolites
• CPC Class Codes: B01D 2253/30 Physical properties of adsorbents
• CPC Class Codes: B01D 2255/50 Zeolites
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/02 by adsorption, e.g. preparative gas chromatography solid sorbent compositions B01J20/00, preparation of inorganic compounds or elements C01
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: B01J 20/22 comprising organic material
• CPC Class Codes: B01J 20/3231 characterised by the coating or impregnating layer
• CPC Class Codes: B60L 2210/12 Buck converters
• CPC Class Codes: B60L 2240/527 Voltage
• CPC Class Codes: B60L 2240/529 Current
• CPC Class Codes: B60L 53/305 Communication interfaces
• CPC Class Codes: B60L 53/63 in response to network capacity
• CPC Class Codes: B60L 53/65 involving identification of vehicles or their battery types
• CPC Class Codes: B60L 53/665 Methods related to measuring, billing or payment
• CPC Class Codes: B60L 58/21 having the same nominal voltage
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: Y02C 20/40 of CO2
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y02T 90/12 : Electric charging stations
• CPC Class Codes: Y02T 90/14 : Plug-in electric vehicles
• CPC Class Codes: Y02T 90/16 : Information or communication technologies improving the operation of electric vehicles
• CPC Class Codes: Y02T 90/167 : Systems integrating technologies related to power network operation and communication or information technologies for supporting the interoperability of electric or hybrid vehicles, i.e. smartgrids as interface for battery charging of electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: Y04S 10/126 : the energy generation units being or involving electric vehicles [EV] or hybrid vehicles [HEV], i.e. power aggregation of EV or HEV, vehicle to grid arrangements [V2G]
• CPC Class Codes: Y04S 30/14 : Details associated with the interoperability, e.g. vehicle recognition, authentication, identification or billing
• CPC Class Codes: Y10T 29/49002 : Electrical device making

Abstract

A high voltage and high current direct current (DC) power meter utilizes step down circuits and optocoupling to generate analog signals that are representative of current through a load and voltage across the load, but that are scaled appropriately for processing by analog to digital conversion circuitry. Power meters consistent with the invention in many cases may be inexpensive, small, solid state and very accurate, and adaptable for use in measuring a wide range of high voltages and currents. A high voltage and high current DC power meter, a method of assembling such a power meter, a method of calculating power consumed by a load with such a power meter, an apparatus to calculate energy consumed by a load, and a program product to calculate energy consumed by the load are provided.

Claims

1. A high voltage and high current direct current (DC) power meter, comprising:

a current step down circuit configured to sense a current applied to a load by a power source, the current step down circuit including a shunt element coupled in series with the load and configured to generate a first analog signal having a voltage representative of current through the load;

a voltage step down circuit configured to sense a voltage across the load, the voltage step down circuit including a voltage divider coupled in parallel with the load and configured to generate a second analog signal having a voltage representative of voltage across the load;

a first isolation amplifier circuit including a first optocoupler and configured to generate from the first analog signal a first isolated analog signal having a voltage representative of the current through the load;

a second isolation amplifier circuit including a second optocoupler and configured to generate from the second analog signal a second isolated analog signal having a voltage representative of the voltage across the load;

an analog to digital conversion circuit isolated from the current and voltage step down circuits by the first and second isolation amplifier circuits and configured to respectively generate from the first and second isolated analog signals first and second digital signals respectively representative of the current through the load and the voltage across the load; and

a controller coupled to the analog to digital conversion circuit and configured to calculate consumed energy for the load by calculating instantaneous power consumed by the load at a plurality of sample points using the first and second digital signals and integrating the instantaneous power over time.

2. The high voltage and high current DC power meter of claim 1, wherein the controller is further configured to calculate a cost using the calculated consumed energy and a rate.

3. The high voltage and high current DC power meter of claim 1, wherein the current and voltage step down circuits each further include an amplifier circuit comprising an op-amp.

4. The high voltage and high current DC power meter of claim 1, wherein the first and second isolation amplifier circuits each include first and second op-amps coupled to inputs and outputs of the respective first and second optocouplers to configure the first and second optocouplers to output linear signals in a photoconductive coupling mode.

5. A charging station for an electric vehicle comprising the high voltage and high current DC power meter of claim 1.

6. A method of assembling a high voltage and high current direct current (DC) power meter, comprising:

configuring a current step down circuit that includes a shunt element adaptable to couple in series with a load and configured to generate a first analog signal having a voltage representative of a current through the load;

configuring a voltage step down circuit that includes a voltage divider adaptable to couple in parallel with the load and configured to generate a second analog signal having a voltage representative of a voltage across the load;

coupling a first isolation amplifier circuit that includes a first optocoupler to the first analog signal to generate a first isolated analog signal having a voltage representative of the current through the load;

coupling a second isolation amplifier circuit that includes a second optocoupler to the second analog signal to generate a second isolated analog signal having a voltage representative of the voltage through the load.

7. The method of claim 6, further comprising:

coupling a first analog-to-digital (A/D) converter to the first isolated analog signal to generate a first digital signal that includes first data indicating the current through the load; and

coupling a second ND converter to the second isolated analog signal to generate a second digital signal that includes second data indicating the current through the load.

8. The method of claim 7, further comprising:

coupling a controller to the first ND converter and the second A/D converter to calculate consumed energy for the load by calculating instantaneous power consumed by the load at a plurality of sample points using the first and second data and integrating the instantaneous power over time.

9. A method of calculating power consumed by a load, comprising:

coupling at least a portion of a current step down circuit in series with a load;

generating a first analog signal that is representative of a current through the load with the current step down circuit;

coupling at least a portion of a voltage step down circuit in parallel with the load;

generating a second analog signal that is representative of a voltage across the load with the voltage step down circuit;

optoelectrically isolating the first analog signal to generate a first isolated analog signal;

optoelectrically isolating the second analog signal to generate a second isolated analog signal;

converting the first and second isolated analog signals into respective first and second digital signals; and

calculating power consumed by the load based upon the first and second digital signals.

10. The method of claim 9, wherein coupling the at least a portion of the current step down circuit in series with the load includes coupling a shunt element of the current step down circuit in series with the load.

11. The method of claim 9, wherein coupling the at least a portion of the voltage step down circuit in parallel with the load includes coupling a voltage divider of the voltage step down circuit in parallel with the load.

12. The method of claim 9, wherein calculating the power consumed by the load further comprises:

storing the first digital signal in a first array; and

storing the second digital signal in a second array.

13. The method of claim 9, further comprising:

converting the first digital signal which is representative of the current through the load with the current step down circuit into an actual value of current through the load by dividing the first digital signal by a resistance value associated with the load.

14. The method of claim 13, further comprising:

converting the second digital signal which is representative of the voltage across the load with the voltage step down circuit into a normalized voltage by multiplying the second digital signal by a predetermined value.

15. The method of claim 14, wherein calculating the power consumed by the load includes:

multiplying the actual value of the current through the load by the normalized voltage.

16. The method of claim 9, wherein calculating the power consumed by the load includes:

calculating a plurality of data points representative of the power consumed by the load over a corresponding plurality of time points.

17. The method of claim 16, further comprising:

performing a trapezoidal integration of the plurality of data points over the plurality of time points to determine kilowatt hours of power consumed.

18. The method of claim 17, further comprising:

indicating a cost associated with the kilowatt hours of power consumed.