Energy harvesting for wireless sensor operation and data transmission

• US 7,081,693 B2
• Filed: 03/05/2003
• Issued: 07/25/2006
• Est. Priority Date: 03/07/2002
• Status: Active Grant

• Current Assignee: Hottinger Bruel & Kjaer Incorporated
• Original Assignee: MicroStrain, Inc. (Spectris PLC)
• Inventors: Arms, Steven W., Hamel, Michael John, Townsend, Christopher P, Churchill, David L.
• Primary Examiner(s): PARRIES, DRU M
• Application Number:
  US10/379,223
• Publication Number:
  US 20040078662A1
• Time in Patent Office: 1,238 Days
• Field of Search: 307/151, 310/339
• US Class Current: 307/151
• CPC Class Codes: B60C 23/0411 Piezoelectric generators
• CPC Class Codes: H02J 7/32 for charging batteries from a charging set comprising a non-electric prime mover rotating at constant speed
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: H02N 2/186 Vibration harvesters
• CPC Class Codes: H10N 30/306 Cantilevers

Abstract

A device for powering a load from an ambient source of energy is provided. The device includes an energy harvesting device for harvesting energy from the ambient source of energy wherein the rate energy is harvested from the ambient source of energy is below that required for directly powering the load. A storage device is connected to the energy harvesting device. The storage device receives electrical energy from the energy harvesting device and is for storing the electrical energy. A controller is connected to the storage device is for monitoring the amount of electrical energy stored in the storage device and for switchably connecting the storage device to the load when the stored energy exceeds a first threshold. The system can be used for powering a sensor and for transmitting sensor data, such as tire pressure.

Claims

1. A system comprising:

an ambient source of energy including at least one from the group including infrastructure, a vehicle, and a machine;

ambient energy provided by said ambient source of energy, including at least one from the group including ambient mechanical energy and ambient magnetic field coupled energy; and

a circuit including an energy harvesting device, a load, a storage device, and a controller, wherein said circuit is mounted for harvesting said ambient energy from said ambient source of energy and converting said ambient energy into electrical energy, wherein said electrical energy is harvested from said ambient source of energy at a rate below that required for directly powering said load;

wherein said storage device is connected to receive said electrical energy from said energy harvesting device, wherein said storage device is for storing said electrical energy; and

wherein said a controller is connected to said storage device for monitoring the amount of electrical energy stored in said storage device and for switchably connecting said storage device to said load when said stored energy exceeds a first threshold.

2. A system as recited in claim 1, wherein said controller is powered by energy stored in said storage device.

3. A system as recited in claim 1, wherein said controller is further for switchably disconnecting said storage device from the load when said stored energy is below a second threshold.

4. A system as recited in claim 3, wherein said controller includes a monitoring device and a first switch.

5. A system as recited in claim 4, wherein said monitoring device includes at least one from the group including a voltage sensitive switch and a voltage comparator.

6. A system as recited in claim 5, wherein said monitoring device includes an integrated circuit having said voltage comparator and a reference voltage source.

7. A system as recited in claim 5, wherein said voltage comparator monitors its input voltage relative to a reference voltage and wherein said first threshold is set by said reference voltage.

8. A system as recited in claim 7, wherein said monitoring device further includes an internal switch, wherein an output of said monitoring device causes said internal switch to close when voltage across said storage device reaches or exceeds said first threshold to connect said storage device to the load for using said stored energy.

9. A system as recited in claim 8, wherein an output of said monitoring device causes said internal switch to open when storage device voltage discharges to a second threshold to disconnect said storage device from the load.

10. A system as recited in claim 4, wherein said first switch is for holding the load in an off state while voltage to said monitoring device is below a level needed for properly operating said monitoring device.

11. A system as recited in claim 10, wherein said first switch has a gate connected to a terminal of said storage device.

12. A system as recited in claim 10, wherein said first switch has a first terminal connected to the load and a second terminal connected to ground.

13. A system as recited in claim 1, wherein said energy harvesting device comprises a piezoelectric transducer (PZT) for generating electrical energy from said ambient mechanical energy.

14. A system as recited in claim 13, wherein said piezoelectric transducer is connected to said storage device through a rectifier.

15. A system as recited in claim 14, further comprising a circuit having an impedance approximately matching load impedance of said PZT to improve efficiency of energy collection.

16. A system as recited in claim 15, wherein said circuit comprises a small capacitor and a DC—

DC converter to transfer charge from said small capacitor to said storage device.

17. A system as recited in claim 16, wherein said circuit further comprises a second switch connected to a terminal of said small capacitor, wherein said second switch enables said DC—

DC converter when voltage across said small capacitor reaches a third threshold value.

18. A system as recited in claim 17, wherein said third threshold value is a multiple of a turn-on voltage of said second switch.

19. A system as recited in claim 18, wherein said multiple is provided by a voltage divider.

20. A system as recited in claim 19, wherein said voltage divider has a total resistance exceeding 10 megohms.

21. A system as recited in claim 17, further comprising a timing capacitor for providing an RC time delay to keep said second switch on while said small capacitor discharges.

22. A system as recited in claim 13, wherein said PZT is mounted on a tuned flexural element.

23. A system as recited in claim 22, wherein said tuned flexural element comprises a cantilever beam.

24. A system as recited in claim 23, wherein said cantilever beam is tapered.

25. A system as recited in claim 24, wherein magnitude of said taper is set to provide a constant strain along length of said cantilever beam.

26. A system as recited in claim 22, wherein said tuned flexural element includes an adjustable mass.

27. A system as recited in claim 13, wherein said piezoelectric transducer is attached to a structural member subject to strain.

28. A system as recited in claim 13, wherein said a piezoelectric transducer comprises at least one from the group including a piezoelectric fiber, a piezoelectric hard ceramic and a piezoelectric polymer.

29. A system as recited in claim 13, wherein said piezoelectric transducer is excited by at least one from the group including wind, water, wave, tide, strain, and vibrational energy.

30. A system as recited in claim 13, wherein said storage device comprises a low impedance high capacity storage device, said circuit further comprising:

a reactive device having a high impedance approximately matching impedance of said piezoelectric transducer at its operating frequency for efficiently transferring electrical energy from said piezoelectric transducer to said reactive device; and

a monitoring circuit for monitoring voltage across said reactive device and for transferring said electrical energy from said reactive device to said low impedance high capacity storage device when said voltage across said reactive device reaches a specified voltage value.

31. A system as recited in claim 30, wherein said monitoring circuit provides impedance transformation.

32. A system as recited in claim 31, wherein said monitoring circuit includes a DC—

DC converter and a device for switching on said DC—

DC converter at said specified voltage value.

33. A system as recited in claim 31, wherein said monitoring circuit further includes a device for switching off said DC—

DC converter when said reactive device discharges to a specified discharged voltage value.

34. A system as recited in claim 33, wherein said device for switching off said DC—

DC converter when said reactive device discharges to a specified discharged voltage value comprises a timing circuit.

35. A system as recited in claim 30, wherein said high capacity storage device comprises at least one from the group including a first capacitor and a battery.

36. A system as recited in claim 35, wherein said reactive device comprises a second capacitor.

37. A system as recited in claim 1, wherein said storage device comprises at least one from the group including a battery and a capacitor.

38. A system as recited in claim 37, wherein said battery comprises a thin film battery.

39. A system as recited in claim 1, wherein said ambient magnetic field coupled energy comprises a power transmission line.

40. A system as recited in claim 1, wherein said load comprises at least one from the group including a sensor, a wireless transmitter, a sensor-transmitter network, and an actuator.

41. A system as recited in claim 40, wherein said sensor is a passive sensor.

42. A sensing system as recited in claim 41, wherein said passive sensor can be reset remotely.

43. A sensing system as recited in claim 41, wherein said passive sensor comprises a shape memory alloy.

44. A sensing system as recited in claim 41, wherein said sensor comprises a passive strain accumulation sensor.

45. A sensing system as recited in claim 40, wherein said sensor is embedded in another material.

46. A system as recited in claim 40, wherein said transmitter is for wirelessly transmitting a signal for triggering an action.

47. A system as recited in claim 40, wherein said vehicle includes a tire, wherein said circuit is for mounting on said tire includes said sensor and said wireless transmitter for sensing and transmitting at least one from the group including tire temperature information and tire pressure information.

48. A system as recited in claim 40, wherein said sensor comprises a device to monitor health of said ambient source of energy.

49. A system as recited in claim 1, wherein power is intermittently provided to said load to reduce power consumption.

50. A system as recited in claim 1, wherein said circuit is resistant to degradation from at least one from the group including moisture, salt, and vibration.

51. A system as recited in claim 1, wherein:

said ambient source of energy comprises a rotating part having a measurable parameter; and

said circuit mounted on said rotating part, said circuit further comprising an energy harvesting device, a sensor, and a transmitter, said energy harvesting device for harvesting mechanical energy from said rotating part, said sensor for measuring said parameter of said rotating part, and said transmitter for transmitting at least one from the group including said measurement and data derived from said measurement, wherein said transmitter is powered by energy derived said energy harvesting device.

52. A system as recited in claim 51, wherein said energy harvesting device is capable of harvesting energy from rotation of said rotating part.

53. A system as recited in claim 51, wherein said storage device comprises at least one from the group including a battery and a capacitor.

54. A system as recited in claim 51, wherein said controller switchably connects said storage device to power said transmitter when said stored energy exceeds said first threshold.

55. A system as recited in claim 54, wherein said controller is powered by energy stored in said storage device.

56. A system as recited in claim 54, wherein said controller is further for switchably disconnecting said storage device from said transmitter when said stored energy is below a second threshold.

57. A system as recited in claim 51, wherein said sensor comprises at least one from the group including a temperature sensor, a strain sensor, and a sensor to measure rate of rotation.

58. A system as recited in claim 51, wherein said circuit further comprises a receiver.

59. A system as recited in claim 58, wherein said circuit comprises a transceiver.

60. A system as recited in claim 51, wherein said circuit further comprises a processor for receiving data from said sensor.

61. A system as recited in claim 60, wherein said circuit further comprises an A/D converter for converting sensor data to digital data.

62. A system as recited in claim 61, wherein said circuit further comprises memory for storing said digital sensor data.

63. A system as recited in claim 62, wherein said memory is integral with or connected to said processor.

64. A system as recited in claim 62, wherein said memory is connected to receive and store said digital sensor data.

65. A system as recited in claim 62, wherein said memory contains a unique address.

66. A system as recited in claim 60, wherein said processor contains a program to process said data before transmitting.

67. A system as recited in claim 60, wherein said processor controls operation of said transmitter.

68. A system as recited in claim 51, wherein said circuit further comprises a feedback mechanism to adjust operation of said rotating part based on said measurement.

69. A system as recited in claim 1, wherein:

said ambient source of energy comprises a moving part, wherein said energy harvesting device is mounted on said moving part for harvesting energy from movement of said moving part;

a sensor mounted on said moving part for measuring a parameter of said moving part;

a memory device mounted on said moving part for storing said sensor 8 measurement;

a transmitter mounted on said moving part for transmitting at least one from the group including said measurement and data derived from said measurement, wherein said transmitter is powered by energy derived from said energy harvesting device.

70. A system as recited in claim 69, wherein said energy 14 harvesting device is capable of harvesting energy from at least one from the group including rotation, bending, and vibration of said moving part.

71. A system as recited in claim 69, wherein said sensor comprises at least one from the group including a temperature sensor, a strain sensor, and a sensor to measure movement of said moving part.

72. A system as recited in claim 69, further comprising a receiver mounted on said moving part.

73. A system as recited in claim 72, wherein said transmitter and said receiver comprise a transceiver.

74. A system as recited in claim 69, further comprising a processor mounted on said moving part.

75. A system as recited in claim 74, further comprising an A/D converter for converting sensor data to digital data.

76. A system as recited in claim 75, further comprising memory for storing said digital sensor data.

77. A system as recited in claim 76, wherein said memory is integral with or connected to said processor.

78. A system as recited in claim 76, wherein said memory is connected to receive and store said digital sensor data.

79. A system as recited in claim 46, wherein said memory contains a unique address to identify data transmitted by said transmitter.

80. A system as recited in claim 74, wherein said processor contains a program to process said data before transmitting.

81. A system as recited in claim 74, wherein said processor controls operation of said transmitter.

82. A system as recited in claim 69, wherein said circuit further comprises a feedback mechanism to adjust operation of said moving part based on said measurement.

83. A system as recited in claim 69, wherein said moving part comprises at least one from the group including a tire, a machine, an engine, an engine mount, a shaft, a propeller drive shaft element, a turbine engine component, and a structural support element.

84. A system as recited in claim 30, wherein said circuit further comprises a wireless transmitter or a first transceiver, wherein said high capacity storage device is for powering said wireless transmitter or said first transceiver for wireless communication of information.

85. A system as recited in claim 84, further comprising a sensor, wherein said wireless transmitter or first transceiver is for wireless communication of information from said sensor.

86. A system as recited in claim 85, further comprising a base station for receiving said wirelessly transmitted information.

87. A system as recited in claim 86, wherein said base station comprises a receiver or a second transceiver.

88. A system as recited in claim 87, further comprising a plurality of said circuits, each said circuit capable of wirelessly transmitting information to said base station.

89. A system as recited in claim 88, wherein each of said circuits further comprises an address.

90. A system as recited in claim 89, wherein each of said circuits is capable of at least one from the group including transmitting and recognizing said address.

91. A system as recited in claim 88, wherein each of said circuits comprises a unique identification code.

92. A system as recited in claim 86, wherein said base station comprises an Ethernet enabled receiver.

93. A system as recited in claim 92, wherein said Ethernet enabled receiver uses extensible markup language (XML) data output format to enable multiple users on a local area network to view said information using a standard internet browser.

94. A system as recited in claim 85, wherein said sensor comprises at least one from the group including a temperature sensor, a strain gauge, a pressure sensor, a magnetic field sensor, an accelerometer, a and a DVRT.

95. A system as recited in claim 85, wherein said sensor comprises a device to monitor health of said ambient source of energy.

96. A system as recited in claim 85, further comprising a processor and a data logger for recording sensor data.

97. A system as recited in claim 96, wherein said data logger comprises non-volatile memory.

98. A system as recited in claim 96, wherein said processor orchestrates sample triggering and high speed logging of said sensor data.

99. A system as recited in claim 96, wherein said sensor data is processed locally in said processor and then uploaded when polled by said base station.

100. A system as recited in claim 84, wherein time division multiple access (TDMA) is used to control communications, wherein said circuits are in sleep mode except when awakened to transmit bursts of data.

101. A system as recited in claim 84 wherein said wireless transmitter can transmit frequency shift keyed digital sensor data with checksum bytes.

102. A system as recited in claim 84, wherein said wireless transmitter comprises differential or pseudo-differential channels.

103. A system as recited in claim 84, wherein said circuit further comprises a data logger including on-board non-volatile memory, user programmable digital filter, gain, and sample rates, and built-in error checking of pulse code modulated (PCM) data.

104. A system as recited in claim 103, wherein said data logger is for storing said information for later transmission by said transmitter.

105. A system as recited in claim 30, wherein said high capacity storage device is for powering at least one from the group including a data storage device and an actuator.

106. A system as recited in claim 30, wherein said high capacity storage device is for at least one from the group including powering and reading a sensor.

107. A system as recited in claim 106, further comprising a processor wherein said sensor is programmable by said processor.

108. A system as recited in claim 30, further comprising a tire, wherein said circuit is for mounting on said tire for sensing and transmitting at least one from the group including tire temperature information and tire pressure information.

109. A system as recited in claim 1, wherein said ambient source of energy comprises a moving part, wherein said energy harvesting device is mounted to convert said ambient mechanical energy of said moving part into electrical energy.

110. A system as recited in claim 109, wherein said storage device comprises at least one from the group including a battery and a capacitor.

111. A system as recited in claim 109, wherein said controller provides a signal derived from amount of electrical energy stored in said storage device.

112. A system as recited in claim 109, wherein said component comprises at least one from the group including a sensor, an A/D converter, a memory, a transmitter, and a transceiver.

113. A system as recited in claim 109, wherein said controller controls operation by controlling provision of power.

114. A system as recited in claim 109, wherein said controller controls operation by controlling clock rate.

115. A system as recited in claim 109, wherein said ambient mechanical energy comprises at least one from the group including vibrational energy and rotational energy.

116. A system as recited in claim 109, wherein said controller can be programmed with a program.

117. A system as recited in claim 1, wherein said ambient source of energy comprises a rotating part, wherein said energy harvesting device is mounted on said rotating part, wherein said energy harvesting circuit device is for harvesting mechanical energy from motion of said rotating part and converting said mechanical energy into electricity, further comprising a radio frequency communications device mounted on said rotating part and connected to receive electricity derived from said energy harvesting device for powering said radio frequency communications device.

118. A system as recited in claim 117, wherein said radio frequency communications device comprises a transmitter.

119. A system as recited in claim 117, further comprising a sensor, wherein data derived from said sensor is transmitted from said rotating part with said transmitter.

120. A system as recited in claim 117, wherein said ambient mechanical energy comprises rotational energy of said rotating part.

121. A system as recited in claim 1, wherein said ambient mechanical energy includes at least one from the group including rotation, bending, and vibration.

122. A system as recited in claim 1, wherein said infrastructure includes a bridge.

123. A system for powering a load, comprising:

an energy harvesting device for harvesting energy from a vibrating ambient source of energy, wherein the rate energy is harvested from said vibrating ambient source of energy is below that required for directly powering the load;

a storage device connected to said energy harvesting device, wherein said storage device receives electrical energy from said energy harvesting device and wherein said storage device is for storing said electrical energy; and

a controller connected to said storage device for monitoring the amount of electrical energy stored in said storage device and for switchably connecting said storage device to the load when said stored energy exceeds a first threshold.

124. A system for powering a load, comprising:

an energy harvesting device for harvesting energy from a rotating ambient source of energy, wherein the rate energy is harvested from said rotating ambient source of energy is below that required for directly powering the load;

a storage device connected to said energy harvesting device, wherein said storage device receives electrical energy from said energy harvesting device and wherein said storage device is for storing said electrical energy; and

a controller connected to said storage device for monitoring the amount of electrical energy stored in said storage device and for switchably connecting said storage device to the load when said stored energy exceeds a first threshold.