Electronic load for the testing of electrochemical energy conversion devices

• US 6,697,245 B2
• Filed: 08/31/2001
• Issued: 02/24/2004
• Est. Priority Date: 03/12/1999
• Status: Expired due to Fees

• Current Assignee: IND, LLC
• Original Assignee: Lynntech Incorporated
• Inventors: Andrews, Craig C.
• Primary Examiner(s): HUYNH, KIM NGOC
• Application Number:
  US09/945,366
• Publication Number:
  US 20020071232A1
• Time in Patent Office: 907 Days
• Field of Search: 361/78, 361/79, 361/93.1, 361/93.2, 327/50, 327/74, 327/87, 327/306, 327/309, 323/426, 323/425
• US Class Current: 361/93.2
• CPC Class Codes: G01R 31/00 Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere measuring superconductive properties G01R33/1238; testing or measuring semiconductors or solid state devices during manufacture H01L22/00; testing line transmission systems H04B3/46
• CPC Class Codes: H01M 10/4285 Testing apparatus
• CPC Class Codes: H01M 8/04298 Processes for controlling fuel cells or fuel cell systems
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04679 of fuel cell stacks
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

In a load for testing an energy production device, such as a fuel cell, a technique is provided for sensing one or more operational parameters for each of a plurality field effect transistors. Analog and digital feedback are provided to adjust the control signal to the FETs to ensure that each remains within its individual safe operating area. The technique preferably takes all of the various operational parameters into account to determine if any individual FET is approaching the SOA boundary, and prevent that single FET from leaving the SOA while continuing to manage the operation of the entire load.

Claims

1. A system for testing an energy generation device, the system comprising:

a load comprising a plurality of field effect transistors coupled in parallel, the load including a positive input terminal and a negative input terminal;

a pair of electrical nodes to receive an energy generation device under test, with a first node coupled to the positive input terminal of the load, and a second node coupled to the negative input terminal of the load through a resistive element;

a means for sensing the voltage drop across the resistive element;

a difference amplifier to receive the sensed voltage drop across the resistive element and to provide an output which is a function of the sensed voltage drop; and

a feedback and control loop to receive the output of the difference amplifier and a control signal from a control element, the feedback and control loop providing an input to the load.

2. The system of claim 1, further comprising a protection circuit in a load adapted to test an electrical energy generation device, the circuit comprising:

means for sensing one or more operational parameters of one of the field effect transistor in the load; and

means for adjusting the current through the field effect transistor in response to the one or more sensed parameters to prevent the transistor from operating outside its safe operating area.

3. The system of claim 2, wherein the protection circuit parameter comprises operating current.

4. The system of claim 2, wherein the protection circuit parameter comprises a temperature.

5. The system of claim 2, wherein the protection circuit further comprises:

means for sensing one or more operational parameters of each of the plurality of field effect transistors in the load individually; and

means for adjusting the current through each of the plurality of field effect transistors individually in response to the respective one or more sensed parameters.

6. The system of claim 2, wherein the means for sensing are components having a characteristic parameter that is a function of the operational parameter.

7. The system of claim 6, wherein one of the one or more operational parameters is temperature.

8. The system of claim 6, wherein one of the one or more operational parameters is current.

9. The system of claim 2, wherein the protection circuit means for sensing comprises a resistor having a predetermined temperature coefficient.

10. The system of claim 2, wherein the protection circuit further comprises an analog feedback loop in the load whose output changes with changes in the resistance of the load.

11. The system of claim 10, wherein the feedback loop comprises:

a shunt in series with the field effect transistor;

an operational amplifier having its inverting input coupled to one end of the shunt; and

the non-inverting input of the operational amplifier coupled to a voltage source referenced to the other end of the shunt.

12. The system of claim 11, wherein the output of the operational amplifier provides a control signal to the gates of the field effect transistors of the load.

13. The system of claim 10, further comprising a digital programmable device providing a control signal to the analog feedback loop to alter the operation of the feedback loop.

14. The system of claim 1, further comprising an amplifier to receive the sensed voltage drop across the resistive element and to provide an output to the control element, whereby the control element alters the first control signal to the first input of the load in response to a change in the sensed voltage drop.

15. The system of claim 1, further comprising a temperature sensor for sensing the operational temperature of the field effect transistors and to provide a sensed temperature signal to the control element to alter the control signal to the input of the load in response to a change in the sensed temperature.

16. The system of claim 15, wherein the load further comprises one or more power resistors in series with one or more of the plurality of field effect transistors.

17. The system of claim 1, wherein the load further comprises one or more power resistors in series with one or more of the plurality of field effect transistors.

18. A system for testing an energy generation device, the system comprising:

a load comprising a plurality of field effect transistors coupled in parallel, the load including a positive input terminal and a negative input terminal;

a pair of electrical nodes to receive an energy generation device under test, with a first node coupled to the positive input terminal of the load, and a second node coupled to the negative input terminal of the load;

a means for sensing the current through the load;

a control element coupled to the positive input terminal of the load, the control element further providing a first control signal to a first input to the load; and

a feedback amplifier to receive the signal from the means for sensing the current and a second control signal from the control element, the feedback amplifier providing a second input to the load.

19. The system of claim 18, further comprising an amplifier to receive the signal from the means for sensing current and to provide an output to the control element, whereby the control element alters the first control signal to the first input of the load in response to a change in the sensed current.

20. The system of claim 18, further comprising a temperature sensor for sensing the operational temperature of the field effect transistors and to provide a sensed temperature signal to the control element to alter the first control signal to the first input of the load in response to a change in the sensed temperature.

21. The system of claim 18, further comprising a protection circuit in a load adapted to test an electrical energy generation device, the circuit comprising:

means for sensing one or more operational parameters of one of the field effect transistors in the load; and

means for adjusting the current through the field effect transistor in response to the one or more sensed parameters to prevent the transistor from operating outside its safe operating area.

22. The system of claim 18, wherein the protection circuit parameter comprises operating current.

23. The system of claim 18, wherein the protection circuit parameter comprises a temperature.

24. The system of claim 18 wherein the protection circuit further comprises:

means for sensing one or more operational parameters of each of the plurality of field effect transistors in the load individually; and

means for adjusting the current through each of the plurality of field effect transistors individually in response to the respective one or more sensed parameters.

25. The system of claim 21, wherein the means for sensing are components having a characteristic parameter that is a function of the operational parameter.

26. The system of claim 25, wherein one of the one or more operational parameters is temperature.

27. The system of claim 25, wherein one of the one or more operational parameters is current.

28. The system of claim 21, wherein the protection circuit means for sensing comprises a resistor having a predetermined temperature coefficient.

29. The system of claim 21, wherein the protection circuit further comprises an analog feedback loop in the load whose output changes with changes in the resistance of the load.

30. The system of claim 29, wherein the feedback loop comprises:

a current sensing device in series with the field effect transistor; and

an operational amplifier having a first input receiving a signal from the current sensing device and a second input coupled to a voltage source.

31. The system of claim 27, wherein the current sensing device is a shunt.

32. The system of claim 27, wherein the output of the operational amplifier provides a control signal to the gates of the field effect transistors of the load.

33. The system of claim 29, further comprising a digital programmable device providing the second control signal to the analog feedback loop to alter the operation of the feedback loop.

34. The system of claim 18, wherein the load further comprises one or more power resistors in series with one or more of the plurality of field effect transistors.

35. A system for testing an energy generation device, the system comprising:

a load comprising a plurality of field effect transistors coupled in parallel, the load including a positive input terminal and a negative input terminal;

a pair of electrical nodes to receive an energy generation device under test, with a first node coupled to the positive input terminal of the load, and a second node coupled to the negative input terminal of the load;

a means for sensing the current through the load;

a feedback and control loop to receive the signal from the means for sensing the current and a control signal from a control element, the feedback and control loop providing an input to the load; and

a temperature sensor for sensing the operational temperature of the field effect transistors and to provide a sensed temperature signal to the control element to alter the control signal to the input of the load in response to a change in the sensed temperature.

36. The system of claim 35, further comprising a protection circuit in a load adapted to test an energy generation device, the circuit comprising:

means for sensing one or more operational parameters of one of the field effect transistors in the load; and

means for adjusting the current through the field effect transistor in response to the one or more sensed parameters to prevent the transistor from operating outside its safe operating area.

37. The system of claim 36, wherein the protection circuit parameter comprises operating current.

38. The system of claim 36, wherein the protection circuit parameter comprises a temperature.

39. A system for testing an energy generation device, the system comprising:

a load comprising a plurality of field effect transistors coupled in parallel, the load including a positive input terminal and a negative input terminal;

a pair of electrical nodes to receive an energy generation device under test, with a first node coupled to the positive input terminal of the load, and a second node coupled to the negative input terminal of the load;

a means for sensing the current through the load;

a feedback and control loop to receive the signal from the means for sensing the current and a control signal from a control element, the feedback and control loop providing an input to the load; and

a protection circuit in a load adapted to test an energy generation device, the circuit comprising;

means for sensing one or more operational parameters of one of the field effect transistors in the load; and

means for adjusting the current through the field effect transistor in response to the one or more sensed parameters to prevent the transistor from operating outside its safe operating area.

40. The system of claim 39, wherein the protection circuit parameter comprises operating current.

41. The system of claim 39, wherein the protection circuit parameter comprises a temperature.

42. The system of claim 39, wherein the protection circuit further comprises:

means for sensing one or more operational parameters of each of the plurality of field effect transistors in the load individually; and

means for adjusting the current through each of the plurality of field effect transistors individually in response to the respective one or more sensed parameters.

43. The system of claim 39, wherein the means for sensing one or more operational parameters are components having a characteristic parameter that is a function of the operational parameter.

44. The system of claim 39, wherein one of the one or more operational parameters is temperature.

45. The system of claim 44, wherein one of the one or more operational parameters is current.

46. The system of claim 39, wherein the protection circuit means for sensing comprises a resistor having a predetermined temperature coefficient.

47. The system of claim 39, wherein the protection circuit further comprises an analog feedback loop in the load whose output changes with changes in the resistance of the load.

48. The system of claim 47, wherein the feedback loop comprises:

a current sensing device in series with the field effect transistor; and

an operational amplifier having a first input receiving a signal from the current sensing device and a second input coupled to a voltage source.

49. The system of claim 48, wherein the current sensing device is a shunt.

50. The system of claim 48, wherein the output of the operational amplifier provides a control signal to the gates of the field effect transistors of the load.

51. The system of claim 47, further comprising a digital programmable device providing the second control signal to the analog feedback loop to alter the operation of the feedback loop.

52. The system of claim 39, further comprising an amplifier to receive the signal from the means for sensing current and to provide an output to the control element, whereby the control element alters the control signal to the load in response to a change in the sensed current.

53. A system for testing an energy generation device, the system comprising:

a load comprising a plurality of field effect transistors coupled in parallel, the load including a positive input terminal and a negative input terminal;

a pair of electrical nodes to receive an energy generation device under test, with a first node coupled to the positive input terminal of the load, and a second node coupled to the negative input terminal of the load through a resistive element;

a means for sensing the voltage drop across the resistive element;

a difference amplifier to receive the sensed voltage drop across the resistive element and to provide an output which is a function of the sensed voltage drop;

a feedback and control loop to receive the output of the difference amplifier and a control signal from a control element, the feedback and control loop providing an input to the load; and

a protection circuit in a load adapted to test an electrical energy generation device, the circuit comprising;

means for sensing one or more operational parameters of one of the field effect transistor in the load; and

means for adjusting the current through the field effect transistor in response to the one or more sensed parameters to restrict the transistor to operating within its safe operating area.

54. The system of claim 53, wherein the protection circuit parameter comprises operating current.

55. The system of claim 53, wherein the protection circuit parameter comprises a temperature.

56. The system of claim 53, wherein the protection circuit further comprises:

means for sensing one or more operational parameters of each of the plurality of field effect transistors in the load individually; and

means for adjusting the current through each of the plurality of field effect transistors individually in response to the respective one or more sensed parameters.

57. The system of claim 53, wherein the means for sensing are components having a characteristic parameter that is a function of the operational parameter.

58. The system of claim 57, wherein one of the one or more operational parameters is temperature.

59. The system of claim 57, wherein one of the one or more operational parameters is current.

60. The system of claim 53, wherein the protection circuit means for sensing comprises a resistor having a predetermined temperature coefficient.

61. The system of claim 53, wherein the protection circuit further comprises an analog feedback loop in the load whose output changes with changes in the resistance of the load.

62. The system of claim 61, wherein the feedback loop comprises:

a shunt in series with the field effect transistor;

an operational amplifier having its inverting input coupled to one end of the shunt; and

the non-inverting input of the operational amplifier coupled to a voltage source referenced to the other end of the shunt.

63. The system of claim 62, wherein the output of the operational amplifier provides a control signal to the gates of the field effect transistors of the load.

64. The system of claim 61, further comprising a digital programmable device providing a control signal to the analog feedback loop to alter the operation of the feedback loop.

65. The system of claim 53, further comprising an amplifier to receive the sensed voltage drop across the resistive element and to provide an output to the control element, whereby the control element alters the first control signal to the first input of the load in response to a change in the sensed voltage drop.

66. The system of claim 53, wherein the load further comprises one or more power resistors in series with one or more of the plurality of field effect transistors.

67. A system for testing an energy generation device, the system comprising:

a load comprising a plurality of field effect transistors coupled in parallel, the load including a positive input terminal and a negative input terminal;

a pair of electrical nodes to receive an energy generation device under test, with a first node coupled to the positive input terminal of the load, and a second node coupled to the negative input terminal of the load through a resistive element;

a means for sensing the voltage drop across the resistive element;

a difference amplifier to receive the sensed voltage drop across the resistive element and to provide an output which is a function of the sensed voltage drop;

a feedback and control loop to receive the output of the difference amplifier and a control signal from a control element, the feedback and control loop providing an input to the load; and

a temperature sensor for sensing the operational temperature of the field effect transistors and to provide a sensed temperature signal to the control element to alter the control signal to the input of the load in response to a change in the sensed temperature.

68. The system of claim 67, wherein the load further comprises one or more power resistors in series with one or more of the plurality of field effect transistors.

69. A system for testing an energy generation device, the system comprising:

a load comprising a plurality of field effect transistors coupled in parallel, the load including a positive input terminal and a negative input terminal;

a pair of electrical nodes to receive an energy generation device under test, with a first node coupled to the positive input terminal of the load, and a second node coupled to the negative input terminal of the load;

a means for sensing the current through the load;

a control element coupled to the positive input terminal of the load, the control element further providing a first control signal to a first input to the load;

a feedback amplifier to receive the signal from the means for sensing the current and a second control signal from the control element, the feedback amplifier providing a second input to the load; and

a temperature sensor for sensing the operational temperature of the field effect transistors and to provide a sensed temperature signal to the control element to alter the first control signal to the first input of the load in response to a change in the sensed temperature.

70. A system for testing an energy generation device, the system comprising:

a load comprising a plurality of field effect transistors coupled in parallel, the load including a positive input terminal and a negative input terminal;

a pair of electrical nodes to receive an energy generation device under test, with a first node coupled to the positive input terminal of the load, and a second node coupled to the negative input terminal of the load;

a means for sensing the current through the load;

a control element coupled to the positive input terminal of the load, the control element further providing a first control signal to a first input to the load;

a feedback amplifier to receive the signal from the means for sensing the current and a second control signal from the control element, the feedback amplifier providing a second input to the load; and

a protection circuit in a load adapted to test an electrical energy generation device, the circuit comprising;

means for sensing one or more operational parameters of one of the field effect transistors in the load; and

means for adjusting the current through the field effect transistor in response to the one or more sensed parameters to restrict the transistor to operating within its safe operating area.

71. The system of claim 70, wherein the protection circuit parameter comprises operating current.

72. The system of claim 70, wherein the protection circuit parameter comprises a temperature.

73. The system of claim 70 wherein the protection circuit further comprises:

means for sensing one or more operational parameters of each of the plurality of field effect transistors in the load individually; and

means for adjusting the current through each of the plurality of field effect transistors individually in response to the respective one or more sensed parameters.

74. The system of claim 70, wherein the means for sensing are components having a characteristic parameter that is a function of the operational parameter.

75. The system of claim 74, wherein one of the one or more operational parameters is temperature.

76. The system of claim 74, wherein one of the one or more operational parameters is current.

77. The system of claim 70, wherein the protection circuit means for sensing comprises a resistor having a predetermined temperature coefficient.

78. The system of claim 70, wherein the protection circuit further comprises an analog feedback loop in the load whose output changes with changes in the resistance of the load.

79. The system of claim 78, wherein the feedback loop comprises:

a current sensing device in series with the field effect transistor; and

an operational amplifier having a first input receiving a signal from the current sensing device and a second input coupled to a voltage source.

80. The system of claim 78, wherein the current sensing device is a shunt.

81. The system of claim 78, wherein the output of the operational amplifier provides a control signal to the gates of the field effect transistors of the load.

82. The system of claim 77, further comprising a digital programmable device providing the second control signal to the analog feedback loop to alter the operation of the feedback loop.

83. The system of claim 70, wherein the load further comprises one or more power resistors in series with one or more of the plurality of field effect transistors.

84. The system of claim 70, wherein the safe operating area is dynamically determined from the one or more sensed parameters.