Reducing power dissipation in inductive energy transfer systems

Patent metadata

Field	Value
Publication number	US-9837866-B2
Application number	US-201414503363-A
Country	US
Kind code	B2
Filing date	Sep 30, 2014
Priority date	Oct 9, 2013
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

In an inductive energy transfer system, the phase of a signal that is applied to a transmitter coil to transfer energy is adjusted while energy is transferred from the transmitter device to a receiver device. The phase of the signal can be adjusted by changing a state of a DC-to-AC converter from a converting state to a non-converting state. The DC-to-AC converter outputs a signal that is applied to the transmitter coil when the DC-to-AC converter is in a converting state. A signal is not applied to the transmitter coil when the DC-to-AC converter is in a non-converting state.

First claim

What is claimed is:

1. A transmitter device for an inductive energy transfer system, comprising:
a DC-to-AC converter operably connected to a transmitter coil; and
a controller operably connected to the DC-to-AC converter and configured to transmit one or more signals to the DC-to-AC converter to change a state of the DC-to-AC converter between a converting state and a non-converting state when the transmitter coil is transferring energy, the non-converting state comprising a quiescent state in which the DC-to-AC converter electrically couples a first and second lead of the transmitter coil.

2. The transmitter device as in claim 1 , further comprising a clock circuit operably connected to the controller.

3. The transmitter device as in claim 2 , further comprising control loop circuitry operably connected to the clock circuit and configured to adjust the operations of the clock circuit.

4. The transmitter device as in claim 3 , further comprising communication circuitry operably connected to the control loop circuitry.

5. The transmitter device as in claim 1 , further comprising a pulse skip controller operably connected to the controller and configured to transmit a skip signal to the controller to cause the controller to change the state of the DC-to-AC converter from a converting state to a non-converting state.

6. The transmitter device as in claim 1 , wherein the DC-to-AC converter comprises an H bridge circuit.

7. The transmitter device as in claim 6 , wherein the controller is configured to change the state of the H bridge circuit between the converting state and the non-converting state by alternately placing the H bridge circuit in a converting state and in the quiescent state.

8. The transmitter device as in claim 6 , wherein the controller is configured to change the state of the H bridge circuit between the converting state and the non-converting state by alternately placing the H bridge circuit in a converting state and in a high impedance state.

9. An inductive energy transfer system, comprising:
a transmitter device, comprising:
a DC-to-AC converter operably connected to a transmitter coil; and
a controller operably connected to the DC-to-AC converter; and

a receiver device, comprising:
a load operably connected to a receiver coil; and
a sense circuit operably connected to the load to measure a signal level on the load, wherein the controller is configured to transmit one or more signals to the DC-to-AC converter to change a state of the DC-to-AC converter between a converting state and a non-converting state when the transmitter coil is transferring energy to the receiver coil, the non-converting state comprising a quiescent state in which the DC-to-AC converter electrically couples a first and second lead of the transmitter coil.

10. The inductive energy transfer system as in claim 9 , further comprising:
first communication circuitry operably connected to the sense circuit; and
second communication circuitry operably connected to the controller, wherein the first communication circuitry and the second communication circuitry are configured to establish a communication channel between the transmitter and receiver devices.

11. The inductive energy transfer system as in claim 10 , wherein the DC-to-AC converter comprises an H bridge circuit.

12. The inductive energy transfer system as in claim 11 , wherein the controller is configured to change the state of the H bridge circuit between the converting state and the non-converting state by alternately placing the H bridge circuit in a converting state and in the quiescent state.

13. The inductive energy transfer system as in claim 11 , wherein the controller is configured to change the state of the H bridge circuit between the converting state and the non-converting state by alternately placing the H bridge circuit in a converting state and in a high impedance state.

14. The inductive energy transfer system as in claim 11 , wherein the sense circuit is configured to transmit a control signal to the controller over the communication channel when the signal level equals or is beyond a threshold to cause the controller to place the H bridge circuit in a quiescent state.

15. A method of operating a transmitter device in an inductive energy transfer system, the method comprising:
transferring energy using a transmitter coil in the transmitter device; and
during energy transfer, periodically changing a state of a DC-to-AC converter operably connected to the transmitter coil between a converting state and a non-converting state, the non-converting state comprising a quiescent state in which the DC-to-AC converter electrically couples a first and second lead of the transmitter coil.

16. The method as in claim 15 , wherein the DC-to-AC converter comprises an H bridge circuit and the state of the H bridge circuit changes between the converting state and the non-converting state by activating and deactivating switches in the H bridge circuit.

17. The method as in claim 16 , wherein the activating and deactivating switches in the H bridge circuit alternately places the H bridge circuit in a converting state and in a quiescent state.

18. The method as in claim 16 , wherein the activating and deactivating switches in the H bridge circuit alternately places the H bridge circuit in a converting state and in a high impedance state.

19. A method of operating an inductive energy transfer system that includes a transmitter device and a receiver device, the method comprising:
transferring energy from the transmitter device to the receiver device;
measuring a signal level on a load in the receiver device during the transfer of energy;
determining if the signal level equals or is beyond a threshold;
if the signal level equals or is beyond the threshold, transmitting a signal from the receiver device to the transmitter device that indicates the signal level equals or is beyond the threshold; and
based on the received signal, a controller in the transmitter device changing a state of a DC-to-AC converter to a non-converting state comprising a quiescent state in which the DC-to-AC converter shorts a transmitter coil of the transmitter device.

20. The method as in claim 19 , wherein determining if the signal level equals or is beyond a threshold comprises determining if the signal level is equal to or less than a threshold.

21. The method as in claim 19 , wherein the DC-to-AC converter comprises an H bridge circuit and the state of the H bridge circuit changes to the non-converting state by placing the H bridge circuit in the quiescent state.

Assignees

• Apple Inc

Inventors

• Moyer Todd K
• Alves Jeffrey M
• Herbst Steven G
• Ritter David W
• Terlizzi Jeffrey J

Classifications

• H02J50/10 Primary

  using inductive coupling · CPC title

• H02J50/80 Primary

  involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices · CPC title

• H02J5/005 Primary

  Electricity · mapped topic

• H02J17/00

  Electricity · mapped topic

• H02J7/025

  Electricity · mapped topic