Driver for wireless power transmitter sensing required transmit power for optimum efficiency

• US 9,524,824 B2
• Filed: 11/04/2015
• Issued: 12/20/2016
• Est. Priority Date: 10/04/2012
• Status: Active Grant

• Current Assignee: Analog Devices International Unlimited Company (Analog Devices, Inc.)
• Original Assignee: Linear Technology Corporation (Analog Devices, Inc.)
• Inventors: Lisuwandi, Eko Tan
• Primary Examiner(s): BOATENG, ALEXIS ASIEDUA
• Application Number:
  US14/932,891
• Publication Number:
  US 20160072310A1
• Time in Patent Office: 412 Days
• Field of Search: 320/107, 320/108, 320/117, 320/118, 320/119, 320/112, 320/134, 320/126, 320/121, 320/120, 320/103, 320/162, 320/128, 307/66, 307/71, 307/26, 307/46, 307/80, 307/110
• US Class Current: 1/1
• CPC Class Codes: B60L 58/18 of two or more battery modules
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0024 Parallel/serial switching of connection of batteries to charge or load circuit
• CPC Class Codes: H02J 7/00304 Overcurrent protection
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

An auto-resonant driver for a transmitter inductor drives the inductor at an optimal frequency for maximum efficiency. The transmitter inductor is magnetically coupled, but not physically coupled, to a receiver inductor, and the current generated by the receiver inductor is used to power a load. The system may be used, for example, to remotely charge a battery (as part of the load) or provide power to motors or circuits. A feedback circuit is used to generate the resonant driving frequency. A detector in the transmit side wirelessly detects whether there is sufficient current being generated in the receiver side to achieve regulation by a voltage regulator powering the load. This point is achieved when the transmitter inductor peak voltage suddenly increases as the driving pulse width is ramped up. At that point, the pulse width is held constant for optimal efficiency.

Claims

1. A power transmission system for wirelessly supplying power to a load comprising:

a transmitter inductor;

a first switch coupled between a voltage source and the transmitter inductor and controlled to generate a varying current through the transmitter inductor;

a receiver inductor magnetically coupled to the transmitter inductor;

a voltage regulator receiving power from the receiver inductor to generate a regulator output voltage;

a load coupled to an output of the voltage regulator, wherein power in the transmitter inductor is wirelessly coupled to the receiver inductor for being converted to a regulated voltage by the regulator for driving the load;

a peak voltage detector coupled to detect a peak voltage on the transmitter inductor, wherein a peak voltage on the transmitter inductor is affected by an ability of the voltage regulator to achieve regulation for driving the load; and

a controller for controlling a peak current through the transmitter inductor, the controller being controlled to modulate the peak current through the transmitter inductor so as to modulate a peak current through the receiver inductor, wherein the peak voltage on the transmitter inductor increases during a time when the voltage regulator is able to achieve regulation,

wherein the controller is configured to variably increase and decrease the peak current through the transmitter inductor, by modulating the peak current through the transmitter inductor, to detect a level of the peak current through the transmitter inductor that corresponds with the increase of the peak voltage as a result of the voltage regulator achieving regulation, and

wherein the controller is controlled to temporarily cease modulating the peak current through the transmitter inductor, as a result of detecting the increase of the peak voltage, to limit the peak current through the transmitter inductor to a level adequate to supply sufficient voltage to the voltage regulator necessary to achieve regulation.

2. The system of claim 1 wherein the controller is controlled to modulate the peak current through the transmitter inductor by modulating the voltage generated by the voltage source.

3. The system of claim 1 wherein the controller is controlled to modulate the peak current through the transmitter inductor by modulating a pulse width of driving pulses applied to the first switch.

4. The system of claim 1 wherein the receiver inductor is housed along with the load in a device for recharging a battery in the device.

10. The system of claim 1 wherein the controller is controlled to temporarily cease modulating the peak current so that the peak current is set to a level less than 25% above that required for the voltage regulator to achieve regulation.

5. A power transmission method for wirelessly supplying power to a load comprising:

providing a transmitter inductor;

controlling a first switch, coupled between a voltage source and the transmitter inductor, to generate a varying current through the transmitter inductor;

providing a receiver inductor magnetically coupled to the transmitter inductor;

receiving power from the receiver inductor by a voltage regulator to generate a regulator output voltage;

providing a load coupled to an output of the voltage regulator, wherein power in the transmitter inductor is wirelessly coupled to the receiver inductor for being converted to a regulated voltage by the regulator for driving the load;

detecting a peak voltage on the transmitter inductor, wherein a peak voltage on the transmitter inductor is affected by an ability of the voltage regulator, receiving power from the receiver inductor, to achieve regulation for driving the load;

controlling a peak current through the transmitter inductor, the controller being controlled to modulate the peak current through the transmitter inductor so as to modulate a peak current through the receiver inductor, wherein the peak voltage on the transmitter inductor increases during a time when the voltage regulator is able to achieve regulation;

variably increasing and decreasing the peak current through the transmitter inductor, by modulating the peak current through the transmitter inductor, to detect a level of the peak current through the transmitter inductor that corresponds with the increase of the peak voltage as a result of the voltage regulator achieving regulation; and

as a result of detecting the increase of the peak voltage, temporarily ceasing modulating the peak current through the transmitter inductor to limit the peak current through the transmitter inductor to a level adequate to supply sufficient voltage to the voltage regulator necessary to achieve regulation.

6. The method of claim 5 wherein the controller is controlled to modulate the peak current through the transmitter inductor by modulating the voltage generated by the voltage source.

7. The method of claim 5 wherein the controller is controlled to modulate the peak current through the transmitter inductor by modulating a pulse width of driving pulses applied to the first switch.

8. The method of claim 5 wherein the receiver inductor is housed along with the load in a device for recharging a battery in the device.

9. The method of claim 5 wherein the step of temporarily ceasing modulating the peak current comprises temporarily ceasing modulating the peak current so that the peak current is set to a level less than 25% above that required for the voltage regulator to achieve regulation.