REDUCING CORRUPTION OF COMMUNICATION IN A WIRELESS POWER TRANSMISSION SYSTEM

• US 20160308400A1
• Filed: 04/18/2016
• Published: 10/20/2016
• Est. Priority Date: 07/21/2009
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Terry, Stephen Christopher, Brohlin, Paul LeRoy, Khanchandani, Deepak Mohanlal
• Granted Patent: US 9,954,402 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current
• CPC Class Codes: H02J 7/007182 in response to battery voltage

Abstract

An embodiment of the invention provides a method for reducing data corruption in a wireless power transmission system. Power is transmitted from a primary coil to a secondary coil by induction. The voltage induced on the secondary coil by induction is rectified. The change in current supplied to a load configured to be coupled to the wireless power transmission system is limited.

Claims

1. A method for reducing data corruption in a wireless power transmission system comprising:

transmitting power from a primary coil to a secondary coil by induction;

rectifying a voltage induced on the secondary coil by the transmission of the power from the primary coil to the secondary coil;

limiting a change in current supplied to a load configured to be coupled to the wireless power transmission system while the voltage is induced on the secondary coil.

2. The method of claim 1 wherein limiting a change in current supplied to a load while the voltage is induced on the secondary coil comprises:

measuring the current supplied to the load;

setting a current regulation threshold below the measured current supplied to the load.

3. The method of claim 1 wherein limiting a change in current supplied to a load while the voltage is induced on the secondary coil comprises:

measuring the current supplied to the load;

setting a current regulation threshold above the measured current supplied to the load.

4. The method of claim 3 wherein the current regulation threshold is set at less than 100 milliamps above the measured current supplied to the load.

5. The method of claim 1 wherein limiting a change in current supplied to a load while the voltage is induced on the secondary coil comprises:

measuring the current supplied to the load;

setting a current regulation threshold to approximately 200 ma when the measured current is below 200 ma.

6. The method of claim 1 further comprising:

increasing the change in current supplied to the load while the voltage is induced on the secondary coil when there is no communication from the secondary coil to the primary coil.

7. The method of claim 1 wherein the load is a battery.

8. The method of claim 1 wherein the load is a power supply.

9. A wireless power transmission system comprising:

a transmitter;

a receiver having an input and an output;

a load adapted to be coupled to the output of the receiver;

wherein the transmitter is inductively coupled to the receiver;

wherein the transmitter transmits power to the receiver;

wherein the receiver receives the power from the transmitter;

wherein a current supplied to the load while the receiver receives the power remains substantially constant.

10. The wireless power transmission system of claim 9 wherein the transmitter comprises:

a control circuit having a first output and a second output;

a driver circuit having a first input, a second input and an output;

a resonant circuit having an input;

wherein the first output of the control circuit is connected to the first input of the driver circuit and the second output of the control circuit is connected to the second input of the driver;

wherein the output of the driver circuit is connected to the input of the resonant circuit.

11. The wireless power transmission system of claim 10 wherein the driver circuit comprises:

a PFET having a gate, drain and source;

an NFET having a gate, drain and source;

wherein the source of the PFET is connected to VDD, the gate of the PFET is connected to the first input of the driver circuit and the drain of the PFET is connected to the drain of the NFET;

wherein the source of the NFET is connected to ground and the gate of the NFET is connected to the second input of the driver circuit.

12. The wireless power transmission system of claim 10 wherein the resonant circuit comprises:

a capacitor having a first terminal and a second terminal;

a coil having a first terminal and a second terminal;

wherein the first terminal of the capacitor is connected to the input of the resonant circuit and the second terminal of the capacitor is connected to the first terminal of the coil;

wherein the second terminal of the coil is connected to ground.

13. The wireless power transmission system of claim 9 wherein the receiver comprises:

a rectifier circuit having an output;

a switch having an input, a first output and a second output;

a charge control circuit having an input and an output;

wherein the output of the rectifier circuit is connected to the first output of the switch and to the input of the charge control circuit;

wherein the input of the receiver is connected to the input of the switch;

wherein the second output of the switch is connected to ground;

wherein the output of the charge control circuit is connected to the output of the receiver.

14. The wireless power transmission system of claim 13 wherein the rectifier circuit comprises:

a centered-tapped coil having a first terminal, a center-tap terminal and a second terminal;

a first diode having a cathode and an anode;

a second diode having a cathode and an anode;

a capacitor having a first terminal and a second terminal;

wherein the center-tap terminal is connected to ground;

wherein the first terminal of the center-tapped coil is connected to the anode of the first diode;

wherein the second terminal of the center-tapped coil is connected to the anode of the second diode;

wherein the output of the rectifier circuit is connect to the cathode of the first diode, to the cathode of the second diode and to the first terminal of the capacitor.

15. The wireless power transmission system of claim 13 wherein the switch comprises:

a resistor having a first terminal and a second terminal;

an NFET having a gate, drain and source;

wherein the first output of the switch is connected to the first terminal of the resistor;

wherein the second terminal of the resistor is connected to the drain of the NFET;

wherein the input of the switch is connected to the gate of the NFET;

wherein the second output of the switch is connected to ground.

16. The wireless power transmission system of claim 13 wherein the charge control circuit comprises:

a current sensor having an input, a first output and a second output;

a charge pump having an input and an output;

a first op-amp having a first input, a second input and an output;

a second op-amp having a first input, a second input and an output;

an NFET having a gate, drain and source;

a first diode having a cathode and an anode;

a second diode having a cathode and an anode;

a capacitor having a first terminal and a second terminal;

a first resistor having a first terminal and a second terminal;

a second resistor having a first terminal and a second terminal;

a third resistor having a first terminal and a second terminal;

a fourth resistor having a first terminal and a second terminal;

wherein the input of the charge control circuit is connected to the input of the current sensor;

wherein the first output of the current sensor is connected to the input of the charge pump, the drain of the NFET, and the cathode of the second diode;

the second output of the current sensor is connected to the second input of the first op-amp, the first input of the second op-amp and the first terminal of the first resistor;

wherein the first terminal of second resistor is connected to the second input of the second op-amp and the first terminal of the third resistor;

wherein the output of the charge pump is connected to the gate of the NFET and the anode of the first diode;

wherein the output of the first op-amp is connected to the cathode of the first diode;

wherein the output of the second op-amp is connected to the second terminal of the third resistor and the first terminal of the fourth resistor;

wherein the first input of the first op-amp is connected to the second terminal of the fourth resistor and the first terminal of the capacitor;

wherein the output of the charge control circuit is connected to the anode of the second diode and the source of the NFET;

wherein the second terminal of the first resistor, the second terminal of the second resistor and the second connection of the capacitor are connected to ground.

17. The wireless power transmission system of claim 13 wherein the charge control circuit comprises:

a current sensor having an input, a first output and a second output;

an analog-to-digital converter having an input and an output;

a digital-to-analog converter having an input and an output;

an op-amp having a first input, a second input and an output;

an NFET having a gate, drain and source;

a first resistor having a first terminal and a second terminal;

a second resistor having a first terminal and a second terminal;

wherein the input to the charge control circuit is connected to the input of the current sensor;

wherein the first output of the current sensor is connected to the drain of the NFET;

wherein the second output of the current sensor is connected to the input of the analog-to-digital converter and first terminal of the first resistor;

wherein the plurality of outputs from the analog-to-digital converter are connected to the plurality of inputs in the digital-to-analog converter;

wherein the output of the digital-to-analog converter is connected to the first input of the op-amp;

wherein the second terminal of the first resistor is connected to the first terminal of the second resistor and to the second input of the op-amp;

wherein the output from the op-amp is connected to the gate of the NFET;

wherein the source of the NFET is connected to the output of the charge control circuit;

wherein the second terminal of the second resistor is connected to ground.

18. A method for reducing data corruption in a wireless power transmission system comprising:

transmitting power from a primary coil to a secondary coil by induction;

rectifying a voltage induced on the secondary coil by the transmission of the power from the primary coil to the secondary coil;

limiting a change in current supplied to a load configured to be coupled to the wireless power transmission system during a voltage regulation phase while the voltage is induced on the secondary coil.

19. The method of claim 18 wherein the load is a battery charger.

20. The method of claim 18 wherein the load is a power supply in voltage regulation.