ELECTRICAL LOAD MANAGEMENT SYSTEM AND METHOD

• US 20120173033A1
• Filed: 06/30/2011
• Published: 07/05/2012
• Est. Priority Date: 06/30/2010
• Status: Active Grant

• Current Assignee: Ergotron Incorporated (Melrose Industries Plc)
• Original Assignee: Ergotron Incorporated (Melrose Industries Plc)
• Inventors: Tischer, William D.
• Granted Patent: US 8,935,011 B2
• Time in Patent Office: Days
• US Class Current: 700/295
• CPC Class Codes: H02J 2310/22 The load being a portable electronic device
• CPC Class Codes: H02J 2310/60 Limiting power consumption in the network or in one section of the network, e.g. load shedding or peak shaving
• CPC Class Codes: H02J 2310/62 The condition being non-electrical, e.g. temperature
• CPC Class Codes: H02J 3/14 by switching loads on to, or off from, network, e.g. progressively balanced loading
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: Y02B 70/3225 Demand response systems, e.g. load shedding, peak shaving
• CPC Class Codes: Y04S 20/222 Demand response systems, e.g. load shedding, peak shaving

Abstract

A load management system provides an interface between a power input and several switched power outputs and un-switched power outputs. A controller groups the switched power outputs into one or more load groups based on a switched current limit determined for the system and the measured currents of the electrical loads. The load groups are defined so that the sum of electrical load currents in each load group does not exceed the switched current limit. The controller also activates one or more switches to apply electrical power to the load groups according to a power sequence. A method for distributing electrical power to electrical loads using load groups is also provided.

Claims

1. An electrical load management system, comprising:

an electrical power input configured to couple the load management system with a common power source;

a plurality of electrical power outputs configured to couple the load management system with a plurality of electrical loads;

a plurality of switches coupled between the power input and the power outputs;

a first current sensor coupled to the power outputs for sensing a current drawn by one or more of the power outputs; and

a controller coupled to the plurality of switches and the first current sensor, the controller configured to

measure with the first current sensor a current drawn by each of a plurality of electrical loads respectively coupled to the plurality of electrical power outputs,

group the power outputs and respective electrical loads into one or more load groups based on a switched current limit and the measured currents of the electrical loads such that, for each load group, a sum of the measured currents of the electrical loads in the load group does not exceed the switched current limit, and

activate the plurality of switches to apply electrical power from the common power source to the load groups according to a power sequence.

2. The system of claim 1, further comprising an indicator coupled to the controller, wherein the controller is configured to activate the indicator based on a state of the system.

3. The system of claim 1, further comprising a temperature sensor coupled to the controller, wherein the controller is further configured to receive a temperature signal from the temperature sensor and activate one or more of the plurality of switches to turn off one or more of the power outputs based on the temperature signal.

4. The system of claim 1, wherein the electrical power input is configured to couple the load management system with an alternating current (AC) power source, the plurality of switches are configured to switch AC power, and the plurality of electrical power outputs are configured to couple the load management system with a plurality of electrical loads requiring AC power.

5. The system of claim 1, wherein the electrical power input is configured to couple the load management system with a direct current (DC) power source, the plurality of switches are configured to switch DC power, and the plurality of electrical power outputs are configured to couple the load management system with a plurality of electrical loads requiring DC power.

6. The system of claim 1, further comprising an un-switched power output coupled to the electrical power input and a second current sensor coupled to the controller, the un-switched power output configured to couple the load management system with a corresponding un-switched electrical load and the second current sensor configured to sense a current drawn by the un-switched power output.

7. The system of claim 6, wherein the switched current limit is based on the measured current drawn by the un-switched electrical load.

8. The system of claim 6, wherein the controller is configured to measure with the second current sensor the current drawn by the un-switched electrical load before starting the power sequence and/or after completing the power sequence.

9. The system of claim 6, wherein the controller is further configured to

measure with the second current sensor the current drawn by the un-switched electrical load during the power sequence, and

if the measurement of the un-switched electrical load current indicates an increase in the current drawn by the un-switched load, then

adjust the switched current limit based on the increase, and

if the sum of the measured currents of the electrical loads in the load group exceeds the adjusted switched current limit then

interrupt the power sequence and re-measure the current drawn by each of the plurality of electrical loads,

re-group the plurality of electrical loads into one or more load groups based on the adjusted switched current limit and the re-measured currents, and

activate the plurality of switches to apply electrical power from the common power source to each of the re-grouped load groups according to a revised power sequence.

10. The system of claim 1, wherein the controller is further configured to

re-measure the current drawn by each of the plurality of electrical loads,

re-group the plurality of electrical loads into one or more load groups based on the switched current limit and the re-measured currents, and

activate the plurality of switches to apply electrical power from the common power source to each of the re-grouped load groups according to a revised power sequence.

11. The system of claim 10, wherein the controller is further configured to measure the current drawn by each of the plurality of electrical loads during the power sequence, and re-measure and re-group the plurality of electrical loads if the measured current indicates an increase in the current drawn by the electrical loads above the switched current limit during the power sequence.

12. The system of claim 10, wherein the controller is further configured to re-measure and re-group the plurality of electrical loads after completing the power sequence.

13. A charging station, comprising:

an electrical power input configured to couple the charging station with a common power source;

a plurality of switched electrical power outputs configured to couple the charging station with a plurality of electrical loads to be charged;

a plurality of switches coupled between the power input and the switched power outputs;

a first current sensor coupled to the switched power outputs for sensing a current drawn by one or more of the switched power outputs;

an un-switched power output coupled to the electrical power input and configured to couple the charging station with an un-switched electrical load;

a second current sensor coupled to the un-switched power output for sensing a current drawn by the un-switched power output; and

a controller coupled to the plurality of switches, the first current sensor, and the second current sensor, the controller configured to

determine a switched current limit based on the current drawn by the un-switched power output and a current limit of the common power source,

measure with the first current sensor a current drawn by each of the electrical loads respectively coupled to the switched power outputs,

group the switched power outputs and respective electrical loads into one or more load groups based on the switched current limit and the measured currents of the electrical loads such that, for each load group, a sum of the measured currents of the electrical loads in the load group does not exceed the switched current limit, and

activate the plurality of switches to apply electrical power from the common power source to the load groups according to a power sequence.

14. The charging station of claim 13, wherein the controller is configured to measure with the second current sensor the current drawn by the un-switched power output before starting the power sequence and/or after completing the power sequence.

15. The charging station of claim 13, wherein the controller is further configured to

measure with the second current sensor the current drawn by the un-switched power output during the power sequence, and

if the measurement of the un-switched power output current indicates an increase in the current drawn by the un-switched power output, then

adjust the switched current limit based on the increase, and

if the sum of the measured currents of the electrical loads in the load group exceeds the adjusted switched current limit then

interrupt the power sequence and re-measure the current drawn by each of the switched power outputs,

re-group the switched power outputs and respective electrical loads into one or more load groups based on the adjusted switched current limit and the re-measured currents, and

activate the plurality of switches to apply electrical power from the common power source to each of the re-grouped load groups according to a revised power sequence.

16. The charging station of claim 13, wherein the controller is further configured to

re-measure the current drawn by each of the switched power outputs,

re-group the switched power outputs and electrical loads into one or more load groups based on the switched current limit and the re-measured currents, and

activate the plurality of switches to apply electrical power from the common power source to each of the re-grouped load groups according to a revised power sequence.

17. The charging station of claim 16, wherein the controller is further configured to measure the current drawn by each of the switched power outputs during the power sequence, and re-measure and re-group the switched power outputs and electrical loads if the measured current indicates an increase in the current drawn by the switched power outputs above the switched current limit during the power sequence.

18. The charging station of claim 16, wherein the controller is further configured to re-measure and re-group the switched power outputs and electrical loads after completing the power sequence.

19. The charging station of claim 13, wherein the plurality of electrical loads to be charged comprise at least one of a notebook computer, a tablet computer, a cell phone, a smart phone, a personal digital assistant, a camera, a music player, and a global positioning satellite device.

20. The charging station of claim 13, wherein the charging station comprises a notebook charging cart.

21. The charging station of claim 13, wherein the charging station comprises a stationary battery charging station.

22. A method for distributing electrical power to electrical loads, comprising:

measuring a current drawn by each of a plurality of electrical loads coupled to a common power source through a load management system;

grouping the electrical loads into one or more load groups based on a switched current limit and the measured currents of the electrical loads such that, for each load group, a sum of the measured currents of the electrical loads in the load group does not exceed the switched current limit; and

applying electrical power from the common power source to the load groups by switching the electrical power to each of the load groups according to a power sequence.

23. The method of claim 22, wherein measuring the current drawn by each of the plurality of electrical loads comprises applying electrical power to one electrical load at a time.

24. The method of claim 22, wherein grouping the plurality of electrical loads comprises maximizing the number of electrical loads in each load group without exceeding the predetermined switched current limit.

25. The method of claim 24, wherein a first load group in the power sequence is a load group with the largest current draw that does not exceed the switched current limit.

26. The method of claim 22, further comprising simultaneously applying electrical power from the common power source to the load groups according to the power sequence and through the load management system to an un-switched electrical load.

27. The method of claim 26, further comprising measuring a current drawn by the un-switched electrical load, wherein the switched current limit is based on the measured current drawn by the un-switched electrical load.

28. The method of claim 27, further comprising measuring the current drawn by the un-switched electrical load before starting the power sequence and/or after completing the power sequence.

29. The method of claim 27, further comprising measuring the current drawn by the un-switched electrical load during the power sequence, and if measuring the current of the un-switched electrical load indicates an increase in the current drawn by the un-switched load, then further comprising

adjusting the switched current limit based on the increase, and

if the sum of the measured currents of the electrical loads in the load group exceeds the adjusted switched current limit then

interrupting the power sequence and re-measuring the current drawn by each of the plurality of electrical loads,

re-grouping the plurality of electrical loads into one or more load groups based on the adjusted switched current limit and the re-measured currents, and

applying electrical power from the common power source to each of the re-grouped load groups by switching the electrical power to each of the re-grouped load groups according to a revised power sequence.

30. The method of claim 26, wherein the switched current limit is further based on a current limit of the common power source.

31. The method of claim 22, further comprising

re-measuring the current drawn by each of the plurality of electrical loads,

re-grouping the plurality of electrical loads into one or more load groups based on the switched current limit and the re-measured currents, and

applying electrical power from the common power source to each of the re-grouped load groups by switching the electrical power to each of the re-grouped load groups according to a revised power sequence.

32. The method of claim 31, further comprising measuring the current drawn by each of the plurality of electrical loads during the power sequence, and re-measuring and re-grouping the plurality of electrical loads if the measured current indicates an increase in the current drawn by the electrical loads above the switched current limit during the power sequence.

33. The method of claim 31, further comprising re-measuring and re-grouping the plurality of electrical loads after completing the power sequence.

34. The method of claim 22, wherein the load management system is configured for charging batteries.

35. The method of claim 22, wherein the load management system is part of a charging station for charging notebook computers.

36. The method of claim 35, wherein the charging station comprises a notebook charging cart.

37. The method of claim 35, wherein the charging station comprises a notebook charging cart.