Decoupling circuits

• US 20060082323A1
• Filed: 10/11/2005
• Published: 04/20/2006
• Est. Priority Date: 04/09/2003
• Status: Active Grant

• Current Assignee: Auckland UniServices Limited (Auckland University)
• Original Assignee: Auckland UniServices Limited (Auckland University)
• Inventors: Boys, John Talbot, Covic, Grant Anthony
• Granted Patent: US 7,474,062 B2
• Time in Patent Office: Days
• US Class Current: 315/209.R
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02M 3/155 using semiconductor devices only

Abstract

Power taken inductively from the alternating current in a track is received by a resonant circuit which is at least partially decoupled by a switching circuit asynchronously with the frequency of the power supply. The switch on and off time is controlled to regulate the output power, either the voltage or the current output being a function of the switch off time divided by the switch on time.

Claims

1. A switchable circuit for receiving power from an alternating current power supply inductively, which circuit is substantially resonant at the frequency of the received power, but which may be decoupled from the power supply by operating a switch, which switch operates cyclically at a frequency unrelated to the power supply frequency, wherein the theoretical lossless output voltage and the theoretical lossless output current are a function of the fractional time the switch is on divided by the fractional time the switch is off.

2. A switchable circuit as claimed in claim 1 wherein one of the output voltage or the output current is an inverse function of the fractional time on divided by the fractional time off.

3. A switchable circuit for receiving power from an alternating current power supply inductively as claimed in claim 1, wherein the observed Q of the circuit can in operation be reduced to zero by appropriate choice of the fractional time the switch is on.

4. A switchable circuit as claimed in claim 1 wherein the switchable circuit utilises a full wave rectifier and a unidirectional switching component.

5. A switchable circuit as claimed in claim 1 wherein the circuit utilises a pickup coil inductively coupled to the current source and wherein a series resonant circuit is used for the pickup coil.

6. A switchable circuit as claimed in claim 1 wherein the circuit utilises a pickup coil inductively coupled to the current source and wherein a parallel resonant circuit is used for the pickup coil.

7. A circuit as claimed in claim 1 wherein the switchable circuit uses a buck-boost configuration on the output side of the circuit.

8. A circuit as claimed in claim 5 wherein the switch is a serially disposed switch.

9. A circuit as claimed in claim 1 wherein the switchable circuit uses a Cuk configuration on the output side of the circuit.

10. A circuit as claimed in claim 7 wherein the switch is a parallel disposed switch.

11. A switchable circuit as claimed in claim 1 wherein the switch is continually switched at a frequency higher than the power supply frequency and unrelated to the power supply frequency with a variable on/off time to regulate the output voltage or current.

12. A switchable circuit as claimed in claim 1 wherein the switch is continually switched at a frequency lower than the power supply frequency with a variable on/off time to regulate the output voltage and current.

13. A switchable circuit as claimed in claim 1 wherein the output voltage can be higher or lower than the voltage induced in the pickup coil.

14. A switchable circuit as claimed in claim 1 wherein the failure mode due to the failure of a single component is identifiable and the circuit will not self destruct in the event of such a failure.

15. A switchable circuit as claimed in claim 11 wherein the maximum circuit current is limited by a saturable reactor in series.

16. A method of controlling a switchable circuit for receiving power inductively from an alternating current power supply where the receiving circuit is substantially resonant at the power supply operating frequency and the switch operates cyclically to substantially decouple the receiving circuit from the power supply and the switch is cyclically closed at a frequency unrelated to the power supply frequency and the theoretical lossless output current and the theoretical lossless output voltage are functions of the time per cycle the switch is on divided by the time per cycle the switch is off wherein the cyclical time the switch is closed is regulated to maintain either the required output current or output voltage.