METHOD AND APPARATUS FOR HIGH EFFICIENCY AC/DC CONVERSION OF LOW VOLTAGE INPUT

• US 20110121659A1
• Filed: 11/19/2010
• Published: 05/26/2011
• Est. Priority Date: 11/19/2009
• Status: Active Grant

• Current Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Original Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Inventors: Rao, Yuan, Cheng, Shuo
• Granted Patent: US 8,743,577 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: H02M 7/06 using discharge tubes without control electrode or semiconductor devices without control electrode
• CPC Class Codes: H02M 7/217 using semiconductor devices only
• CPC Class Codes: H02M 7/2195 the switches being synchronously commutated at the same frequency of the AC input voltage
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

Embodiments of the subject invention relate to a method and apparatus for providing a low-power AC/DC converter designed to operate with very low input voltage amplitudes. Specific embodiments can operate with input voltages less than or equal to 1 V, less than or equal to 200 mV, and as low as 20 mV, respectively. Embodiments of the subject low-power AC/DC converter can be utilized in magnetic induction energy harvester systems. With reference to a specific embodiment, a maximum efficiency of 92% was achieved for a 1 V input, and efficiencies exceeding 70% were achieved for a 200 mV input. A specific embodiment functioned properly when connected to a magnetic energy harvester device operating below 200 mV input.

Claims

1. An AC/DC converter, comprising:

a first comparator;

a first active diode;

a first switch;

a second comparator;

a second active diode;

a second switch;

a first energy storage element; and

a second energy storage element;

wherein the converter is adapted to connect to an input AC voltage source such that the first active diode is in series between the input AC voltage source and the first energy storage element and the second active diode is in series between the input AC voltage and the second energy storage element, such that when the voltage of the input AC voltage source is below a voltage of the first energy storage element, the first active diode turns on and current flows from the first energy storage element to the input AC voltage source, and when the voltage of the input AC voltage source is higher than the voltage of the second energy storage element, current flows from the input AC voltage source to the second energy storage element.

2. The converter according to claim 1,

wherein the first active diode comprises a first comparator and a first switch,

wherein the second active diode comprises a second comparator and a second switch.

3. The converter according to claim 2, wherein the first switch is selected from the group consisting of:

an electromechanical switch, a bipolar junction transistor, an analog switch, a junction gate field-effect transistor, and a MOS transistor.

4. The converter according to claim 2, wherein the first switch is a first transistor, wherein the second switch is a second transistor.

5. The converter according to claim 4, wherein the first and second transistors are bipolar junction transistors (BJT).

6. The converter according to claim 4, wherein the first and second transistors are junction gate field-effect transistor (JFET).

7. The converter according to claim 4, wherein the first and second transistors are MOS transistors.

8. The converter according to claim 4, wherein the second transistor is an NMOS transistor and the first transistor is a PMOS transistor.

9. The converter according to claim 8, wherein the second comparator comprises a second positive input port connected to a source of the NMOS transistor.

10. The converter according to claim 8, wherein the first comparator comprises a first positive input port connected to a drain of the PMOS transistor.

11. The converter according to claim 9, wherein the second comparator comprises a second negative input port connected to a drain of the NMOS transistor.

12. The converter according to claim 10, wherein the first comparator comprises a first negative input port connected to a source of the PMOS transistor.

13. The converter according to claim 1, further comprising a first resistor in series with the first active diode between the input AC power source and the first energy storage element.

14. The converter according to claim 7, further comprising a first low pass filter in parallel with the first energy storage element.

15. The converter according to claim 1, further comprising a shunt capacitor connected across output terminals of the input AC power source.

16. The converter according to claim 1, further comprising a linear or switching regulator connected to the output of the converter.

17. The converter according to claim 1, wherein the converter operates with an input AC power source of less than or equal to 1 V.

18. The converter according to claim 1, wherein the converter operates with an input AC power source of less than or equal to 200 mV.

19. The converter according to claim 1, wherein the converter operates with an input AC power source of less than or equal to 20 mV.

20. The converter according to claim 18, wherein the converter has an efficiency greater than 70%.

21. The converter according to claim 2,

wherein the first comparator comprises a first positive input port, a first negative input port, at least one first bias port, and a first output port;

wherein the First switch comprises a first transistor, where the first transistor has a first gate, a first drain, and a first source;

wherein the second comparator comprises a second positive input port, a second negative input port, at least one second bias port, and a second output port;

wherein the second switch comprises a second transistor, wherein the second transistor comprises a second gate, a second drain, and a second source;

at least one first bias voltage supply;

at least one second bias voltage supply;

a first energy storage element; and

a second energy storage element;

wherein the at least one first bias voltage supply is connected to the at least one bias port so as to provide a first bias voltage to the first comparator, wherein the first output port is connected to the first gate, wherein one of the first positive input port and the first negative input port is connected to the first energy storage element, wherein the other of the first positive input port and the first negative input port is adapted to connect with the input AC power source, wherein one of the first drain and first source is adapted to connected with the input AC power source and the other of the first drain and first source is connected with the first energy storage element such that the first transistor is in series between the input AC power source and the first energy storage element, wherein when the input AC voltage is below a voltage of the first energy storage element the first output port voltage turns on the first transistor and current flows from the input AC power source to the first energy storage element,

wherein the at least one second bias voltage supply is connected to the at least one second bias port so as to provide a second bias voltage to the second comparator, wherein the second output port is connected to the second gate, wherein one of the second positive input port and the second negative input port is connected to the second energy storage element, wherein the other of the second positive input port and the second negative input port is adapted to connect with the input AC power source, wherein one of the second drain and the second source is adapted to connect with the input AC power source and the other of the second drain and the second source is connected with the second energy storage element such that the second transistor is in series between the input AC power source and the second energy storage element, wherein when the input AC voltage is above a voltage of the second energy storage element the second output port voltage turns on the second transistor and current flows from the input AC power source to the second energy storage element.

22. A magnetic induction energy harvester system, comprising an AC/DC converter of claim 1.