Inductive power transfer system

• US 10,381,876 B2
• Filed: 11/25/2015
• Issued: 08/13/2019
• Est. Priority Date: 05/30/2013
• Status: Active Grant

• Current Assignee: Drayson Technologies (Europe) Limited
• Original Assignee: Drayson Technologies (Europe) Limited
• Inventors: Mitcheson, Paul David, Lawson, James, Rangel, Manuel Pinuela, Yates, David Christopher
• Primary Examiner(s): Williams, Arun C
• Application Number:
  US14/952,097
• Publication Number:
  US 20160204645A1
• Time in Patent Office: 1,357 Days
• Field of Search: 320108
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02M 7/4815 Resonant converters H02M7/4811 and H02M7/4826 take precedence
• CPC Class Codes: H02M 7/537 using semiconductor devices only, e.g. single switched pulse inverters
• 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

The invention relates to an inductive power transfer transmitter comprising class-E amplifier driver arranged to drive a primary tank circuit including a transmitter coil, in which the driver frequency is tuned to drive the primary tank circuit when the primary tank circuit is in an unloaded condition.

Claims

1. An inductive power transfer transmitter comprising:

a class-E amplifier driver arranged to drive a primary tank circuit including a transmitter coil, in which the driver frequency is tuned to drive the primary tank circuit at semi-resonant frequency when the primary tank circuit is in an unloaded condition,

wherein the primary tank circuit comprises the transmitter coil and a first capacitor arranged in parallel with the transmitter coil, and

the inductive power transfer transmitter further comprises a second capacitor connecting the class-E amplifier driver to the primary tank circuit.

2. A transmitter as claimed in claim 1 in which the input DC voltage is additionally tuned to drive the primary tank circuit at maximum wireless power transfer efficiency when the primary tank is an unloaded condition.

3. A transmitter as claimed in claim 1 in which the driver frequency is different from the primary tank circuit resonant frequency.

4. A transmitter as claimed in claim 1 in which the driver frequency is further tuned to operate the primary tank circuit in a free wheel condition.

5. An inductive power transfer receiver comprising a receiver tank circuit and rectifier, in which the tank circuit is tuned for resonance in the absence of a remote load, wherein the rectifier comprises:

a first diode having a first terminal and a second terminal, and

connected between the first terminal and the second terminal of the first diode, a capacitor or a second diode.

6. A receiver as claimed in claim 5 in which the rectifier is a class-E rectifier.

7. A receiver as claimed in claim 5 in which the receiver tank circuit coil comprises Litz wire.

8. A receiver as claimed in claim 5 in which the receiver tank circuit coil comprises a planar spiral configuration.

9. A receiver as claimed in claim 7 in which the receiver coil is mounted on a PCB.

10. An inductive power transfer receiver comprising a planar spiral Litz wire configuration woven or mounted on a flexible substrate, the flexible substrate being Kapton, cloth, or a thin PCB material having a thickness of 100 μ

m or less.

11. An inductive power transfer system comprising:

an inductive power transfer transmitter comprising a class-E amplifier driver arranged to drive a primary tank circuit including a transmitter coil, in which the driver frequency is tuned to drive the primary tank circuit at semi-resonant frequency when the primary tank circuit is in an unloaded condition,

wherein the primary tank circuit comprises the transmitter coil and a first capacitor arranged in parallel with the transmitter coil, and

the inductive power transfer transmitter further comprises a second capacitor connecting the class-E amplifier driver to the tank circuit; and

an inductive power transfer receiver comprising a receiver tank circuit and rectifier, in which the tank circuit is tuned for resonance in the absence of a remote load.

12. An inductive power transfer system as claimed in claim 11 comprising a long range inductive power transfer system.

13. An inductive power transfer system as claimed in claim 11 comprising a planar transmitter coil forming a base over which a planar receiver coil can be positioned.

14. A system as claimed in claim 13 in which the transmitter coil is augmented with a Helmholtz coil.

15. A system as claimed in claim 13 in which the receiver coil comprises first and second planar spiral coils in parallel.

16. A system as claimed in claim 13 in which the transmitter coil comprises a single loop planar spiral.

17. A system as claimed in claim 13 in which at least one of the transmit and receive coils comprises a planar spiral coil around a central ferrite magnetic coupling element.