ENERGY HARVESTING APPARATUS AND METHOD

• US 20160079791A1
• Filed: 01/07/2015
• Published: 03/17/2016
• Est. Priority Date: 09/15/2014
• Status: Active Grant

• Current Assignee: Korea University Research and Business Foundation (Korea University)
• Original Assignee: Korea University Research and Business Foundation (Korea University)
• Inventors: Kim, Chul Woo, Shim, Min Seob, JUNG, Jun Won, Kim, Jung Moon
• Granted Patent: US 9,793,751 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02J 50/001 Energy harvesting or scavenging
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices

Abstract

Disclosed is an energy harvesting apparatus. The energy harvesting apparatus includes a rectifier for rectifying an alternating current (AC) voltage supplied from an energy source into a direct current (DC) voltage, a charging unit for storing an output voltage of the rectifier, and a maximum power point tracker selectively connected between the rectifier and the charging unit, for differentiating the output voltage of the rectifier in a first connection state, and for controlling the output voltage of the rectifier based on a differentiation result.

Claims

1. An energy harvesting apparatus comprising:

a rectifier for rectifying an alternating current (AC) voltage supplied from an energy source into a direct current (DC) voltage;

a charging unit for storing an output voltage of the rectifier; and

a maximum power point tracker selectively connected between the rectifier and the charging unit, for differentiating the output voltage of the rectifier in a first connection state, and for controlling the output voltage of the rectifier based on a differentiation result.

2. The energy harvesting apparatus according to claim 1, wherein the maximum power point tracker comprises:

a first capacitor connected to an output node of the rectifier;

a voltage controller selectively connected to the first capacitor, for differentiating a voltage of the first capacitor, for detecting a maximum power point based on a differentiation result, and for outputting a control signal corresponding to a detection result; and

a charge sharer for storing a voltage of the output node of the rectifier based on the control signal and distributing the stored voltage as a maximum power point voltage.

3. The energy harvesting apparatus according to claim 2, wherein the first capacitor has capacitance with a nano unit.

4. The energy harvesting apparatus according to claim 2, wherein the voltage controller comprises:

a peak detector for differentiating the voltage of the first capacitor and outputting a differentiation result; and

a control signal generator for generating the control signal based on an output signal of the peak detector.

5. The energy harvesting apparatus according to claim 2, further comprising a charging controller for comparing the output voltage of the rectifier and the maximum power point voltage and controlling an operation of the charging unit based on a comparison result.

6. The energy harvesting apparatus according to claim 5, further comprising a voltage multiplexer (MUX) for supplying power to the charging controller,

wherein the voltage multiplexer (MUX) comprises an S-R latch and a rising edge detector and prevents delay of output of the voltage multiplexer (MUX).

7. An energy harvesting method comprising:

rectifying an alternating current (AC) voltage supplied from an energy source into a direct current (DC) voltage;

differentiating the rectified voltage and tracking a maximum power point of the rectified voltage based on a differentiation result; and

charging with the rectified voltage while maintaining the rectified voltage when the rectified voltage reaches the maximum power point.

8. The energy harvesting method according to claim 7, wherein the differentiating and the tracking comprises:

charging a first capacitor with the rectified voltage;

differentiating a voltage of the first capacitor and detecting a maximum power point voltage based on a differentiation result; and

distributing the voltage charged in the first capacitor to second and third capacitors when the maximum power point is detected.

9. The energy harvesting method according to claim 8, wherein the differentiating of the voltage of the first capacitor comprises:

differentiating the voltage of the first capacitor;

comparing the differentiation result with a bias voltage; and

detecting the voltage of the first capacitor as the maximum power point voltage at a time point when the differentiation result becomes smaller than the bias voltage.

10. The energy harvesting method according to claim 8, wherein the first capacitor has capacitance with a nano unit.

11. The energy harvesting method according to claim 7, wherein the charging comprises:

comparing the rectified voltage with the maximum power point voltage;

enhancing the rectified voltage by temporarily stopping charging when the rectified voltage is lower than the maximum power point voltage as a comparison result; and

lowering the rectified voltage by continuously performing charging when the rectified voltage is higher than the maximum power point voltage as the comparison result.