High current voltage regulator

• US 7,907,430 B2
• Filed: 12/18/2008
• Issued: 03/15/2011
• Est. Priority Date: 12/18/2008
• Status: Active Grant

• Current Assignee: Waikatolink Limited (Waikato University)
• Original Assignee: Waikatolink Limited (Waikato University)
• Inventors: Fernando, Lewis Jayathu, Kularatna, Nihal
• Primary Examiner(s): Riley; Shawn
• Application Number:
  US12/338,723
• Publication Number:
  US 20100156369A1
• Time in Patent Office: 817 Days
• Field of Search: 363/59, 323/266, 327/536, 320/167, 320/142
• US Class Current: 363/59
• CPC Class Codes: G05F 1/46 wherein the variable actually regulated by the final control device is dc G05F1/625 takes precedence
• CPC Class Codes: H02M 1/0045 Converters combining the concepts of switch-mode regulation and linear regulation, e.g. linear pre-regulator to switching converter, linear and switching converter in parallel, same converter or same transistor operating either in linear or switching mode
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps
• CPC Class Codes: H02M 3/072 adapted to generate an output voltage whose value is lower than the input voltage

Abstract

A linear voltage regulator which includes on its input side an array of switched super capacitors coupled between the power source and the load. This apparatus is capable of delivering currents typically from milliamperes to greater than several amperes at very low switching frequencies. In addition by using capacitors rather than resistors or transistor devices to drop voltage on the input side, power consumption is reduced. The array of capacitors is switched by simple analog circuitry or a switching logic with or without a processor subsystem and the capacitors themselves are of the super capacitor type, thus providing very high capacitance, and are effectively series connected during certain phases of operation with the input terminal of the conventional linear voltage regulator portion of the apparatus. Energy stored in the super capacitors during the various phases of operation is reused.

Claims

1. A voltage regulation apparatus comprising:

a power supply terminal adapted to be coupled to a power source;

a linear voltage regulator circuit having an input terminal;

a switched capacitor element functioning as a voltage dropper and serially coupled between the power supply terminal and the input terminal of the linear voltage regulator, the switched capacitor element including at least one super capacitor having a capacitance of at least 0.1 farad and at least one transistor or solid state relay; and

an output terminal coupled to an output terminal of the linear voltage regulator.

2. The apparatus of claim 1, wherein the switched capacitor element includes at least two super capacitors each series coupled to at least one switch, the two super capacitors being capable of being serial or parallel coupled by the at least one transistor or solid state relay relative to one another and to the input terminal of the linear voltage regulator.

3. The apparatus of claim 1, further comprising control logic coupled to operate the switched capacitor element.

4. The apparatus of claim 1, wherein the linear voltage regulator circuit is of the series or shunt type.

5. The apparatus of claim 1, wherein the linear voltage regulator circuit is of the low drop out type.

6. The apparatus of claim 1, wherein in operation the apparatus provides a current of at least one ampere at the output terminal.

7. The apparatus of claim 3, wherein the control logic operates the apparatus in at least three phases, including:

a first phase where only a first super capacitor in the switched capacitor element is connected;

a second phase where only a second super capacitor in the switched capacitor element is connected; and

a third phase where neither of the first and second super capacitors are connected to the power supply terminal but both are connected to the input terminal of the linear voltage regulator.

8. A method of providing a regulated voltage from a power source using a capacitance coupled to an input terminal of a linear voltage regulator, comprising the acts of:

series coupling a first super capacitor functioning as a voltage dropper and having a capacitance of at least 0.1 farad in the capacitance between the power source and the input terminal;

disconnecting the first super capacitor and series coupling by a transistor or solid state relay a second super capacitor between the power source and the input terminal of the linear voltage regulator; and

disconnecting the second super capacitor from the power source and discharging both super capacitors to the input terminal.

9. The method of claim 8, further comprising the acts of:

series coupling the super capacitors between the power source and the input terminal; and

disconnecting the super capacitors from the power source, connecting the super capacitors in series and discharging the super capacitors from the input terminal.

10. The method of claim 8, further comprising the acts of:

series coupling the super capacitors between the power source and the input terminal; and

disconnecting the super capacitors from the power source, connecting the super capacitors in parallel and discharging the super capacitors to the input terminal.

11. The method of claim 8, wherein the connecting and disconnecting are performed by switches coupled to a control element.

12. The method of claim 8, wherein the linear voltage regulator is of the series or shunt type.

13. The method of claim 8, wherein the linear voltage regulator is of the low drop out type.

14. The method of claim 8, further comprising outputting a current of at least one ampere from the linear voltage regulator.

15. The method of claim 8, wherein a switching rate of the method is less than about 300 Hz.