Vibration energy harvester for converting mechanical vibrational energy into electrical energy
First Claim
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1. A vibration energy harvester for converting mechanical vibrational energy into electrical energy, the vibration energy harvester comprising:
- a device for generating electrical energy when subjected to mechanical vibration; and
a current control circuit electrically connected to the device for providing a substantially constant output current at an electrical output of the vibration energy harvester, the current control circuit having;
a first controllable variable resistance connected to the electrical output of the vibration energy harvester, the current control circuit adapted to control the first controllable variable resistance to maintain a predetermined input voltage and adapted to control a device output voltage at the electrical output of the vibration energy harvester so that the output voltage does not exceed a predetermined threshold voltage,a second controllable variable resistance connected to the electrical output of the vibration energy harvester, the second controllable variable resistance comprising a shunt resistance between a power line and a ground line of the device, anda reference voltage generator for generating a preset reference voltage, and an error amplifier for comparing the input voltage from the device with the reference voltage for generating a first control signal for selectively adjusting the first-controllable variable resistance when the input voltage is different from the reference voltage.
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Abstract
A vibration energy harvester for converting mechanical vibrational energy into electrical energy, the vibration energy harvester comprising a device for generating electrical energy when subjected to mechanical vibration, and a current control circuit electrically connected to the device for providing a substantially constant output current at an electrical output of the vibration energy harvester.
40 Citations
11 Claims
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1. A vibration energy harvester for converting mechanical vibrational energy into electrical energy, the vibration energy harvester comprising:
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a device for generating electrical energy when subjected to mechanical vibration; and a current control circuit electrically connected to the device for providing a substantially constant output current at an electrical output of the vibration energy harvester, the current control circuit having; a first controllable variable resistance connected to the electrical output of the vibration energy harvester, the current control circuit adapted to control the first controllable variable resistance to maintain a predetermined input voltage and adapted to control a device output voltage at the electrical output of the vibration energy harvester so that the output voltage does not exceed a predetermined threshold voltage, a second controllable variable resistance connected to the electrical output of the vibration energy harvester, the second controllable variable resistance comprising a shunt resistance between a power line and a ground line of the device, and a reference voltage generator for generating a preset reference voltage, and an error amplifier for comparing the input voltage from the device with the reference voltage for generating a first control signal for selectively adjusting the first-controllable variable resistance when the input voltage is different from the reference voltage. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of operating a vibration energy harvester for converting mechanical vibrational energy into electrical energy, the method comprising the steps of:
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a. providing on a vibratable support a device for generating electrical energy when subjected to mechanical vibration; and b. using a current control circuit electrically connected to the device to perform the steps of; providing a substantially constant output current at an electrical output of the vibration energy harvester when the device is vibrated, controlling a first controllable variable resistance connected to the electrical output of the vibration energy harvester so that an input voltage from the device is maintained at a predetermined voltage, comparing the input voltage from the device with a reference voltage, and such comparison generates a first control signal for selectively adjusting the first controllable variable resistance when the input voltage is different from the reference voltage; and controlling an output voltage at the electrical output of the vibration energy harvester so that the output voltage does not exceed a predetermined threshold voltage by varying a second controllable variable resistance connected to the electrical output of the vibration energy harvester; wherein the second controllable variable resistance comprises a shunt resistance between a power line and a ground line of the device. - View Dependent Claims (8, 9, 10)
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11. A vibration energy harvester for converting mechanical vibrational energy into electrical energy, the vibration energy harvester comprising:
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an electromechanical generator for generating electrical energy when subjected to mechanical vibration, and a current control circuit electrically connected to the device for providing a substantially constant output current at an electrical output of the vibration energy harvester, the current control circuit comprising; a first controllable variable resistance connected to the electrical output of the vibration energy harvester, the first controllable variable resistance being selected from the group consisting of a MOSFET and a bipolar junction transistor, a reference voltage generator for generating a preset reference voltage, and an error amplifier for comparing an input voltage from the device with the reference voltage for generating a first control signal for selectively adjusting the first controllable variable resistance when the input voltage is different from the reference voltage, and a second controllable variable resistance connected to the electrical output of the vibration energy harvester, the second controllable variable resistance comprising a shunt resistance between a power line and a ground line of the device; wherein the current control circuit is adapted to control the first controllable variable resistance to maintain a predetermined input voltage and adapted to control a device output voltage at the electrical output of the vibration energy harvester so that the output voltage does not exceed a predetermined threshold voltage.
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Specification