WIRELESSLY POWERED DEVICES

• US 20140145513A1
• Filed: 11/25/2013
• Published: 05/29/2014
• Est. Priority Date: 11/26/2012
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Kapoor, Ajay, Thueringer, Peter
• Granted Patent: US 9,601,268 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: G06K 19/073 Special arrangements for circuits, e.g. for protecting identification code in memory protection against unauthorised use of computer memory G06F12/14
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/0024 Parallel/serial switching of connection of batteries to charge or load circuit
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices

Abstract

A circuit for delivering power to a load from a wireless power supply comprises an inductor coil for placing in the electromagnetic field of an inductor coil of a supply and a switchable capacitor bank with capacitors switchable at least between a series and a parallel configuration. The voltage across the capacitor bank is used as a feedback control parameter for controlling the capacitor bank switching. A voltage regulator is used to supply the load with a constant voltage power supply derived from the capacitor bank output.

Claims

1. A circuit for delivering power to a load from a wireless power supply, comprising:

an inductor coil for placing in the electromagnetic field of an inductor coil of a supply;

a switchable capacitor bank with capacitors switchable at least between a series and a parallel configuration;

a voltage detecting device for measuring the voltage or detecting predetermined voltages across the capacitor bank;

a switch controller for controlling the capacitor bank switching in dependence on the measured or detected voltages; and

a voltage regulator for supplying the load with a constant voltage power supply derived from the capacitor bank output.

2. A circuit as claimed in claim 1, comprising a voltage clipper for limiting the maximum voltage across the capacitor bank.

3. A circuit as claimed in claim 1, comprising a voltage limiter for providing a power down if a minimum voltage is present across the capacitor bank.

4. A circuit as claimed in claim 1, wherein the voltage regulator comprises a low drop out voltage regulator.

5. A circuit as claimed in claim 1, wherein the switch regulator is adapted to control the capacitor bank such that:

during an increase in voltage across the capacitor bank, the capacitor bank is switched from a series configuration to a parallel configuration when the voltage reaches a maximum voltage; and

during a decrease in voltage across the capacitor bank, the capacitor bank is switched from a parallel configuration to a series configuration when the voltage reaches a minimum voltage.

6. A contactless smart card comprising a circuit as claimed in claim 1.

7. A method for delivering power to a load from a wireless power supply, comprising:

placing an inductor in the electromagnetic field of an inductor coil of a supply;

measuring the received voltage or detecting predetermined received voltages;

controlling switching of a capacitor bank which is switchable at least between a series and a parallel configuration in dependence on the measured or detected voltages; and

supplying a load with a constant voltage power supply derived from the capacitor bank output by a voltage regulator.

8. A method as claimed in claim 7, comprising limiting the maximum voltage across the capacitor bank.

9. A method as claimed in claim 7, comprising providing a power down if a minimum voltage is present across the capacitor bank.

10. A method as claimed in claim 7, comprising controlling the capacitor bank such that:

during an increase in voltage across the capacitor bank, the capacitor bank is switched from a series configuration to a parallel configuration when the voltage reaches a maximum voltage; and

during a decrease in voltage across the capacitor bank, the capacitor bank is switched from a parallel configuration to a series configuration when the voltage reaches a minimum voltage.