WIRELESS POWER TRANSMITTER HAVING LOW NOISE AND HIGH EFFICIENCY, AND RELATED METHODS

• US 20140132077A1
• Filed: 11/08/2013
• Published: 05/15/2014
• Est. Priority Date: 11/09/2012
• Status: Active Grant

• Current Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Original Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Inventors: Nalbant, Mehmet K.
• Granted Patent: US 10,211,720 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02M 1/38 Means for preventing simultaneous conduction of switches
• CPC Class Codes: H02M 7/4815 Resonant converters H02M7/4811 and H02M7/4826 take precedence
• CPC Class Codes: H02M 7/538 in a push-pull configuration H02M7/5375 takes precedence ; with oscillating arrangements H02M7/53832, H02M7/53846
• CPC Class Codes: H02M 7/5387 in a bridge configuration
• 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
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing

Abstract

A wireless power transmitter comprises a bridge inverter including a first switch and a second switch coupled together with a first switching node therebetween, and a first capacitor coupled to the first switching node. The transmitter further includes control logic configured to control the first switch and the second switch according to an operating frequency to generate an AC power signal from a DC power signal, and a resonant tank operably coupled to the first switching node of the bridge inverter, the resonant tank configured to receive the AC power signal and generate an electromagnetic field responsive thereto. A method for operating the wireless power transmitter and a method for making the wireless power transmitter are also disclosed.

Claims

1. A wireless power transmitter, comprising:

a bridge inverter including;

a first switch and a second switch coupled together with a first switching node therebetween; and

a first capacitor coupled to the first switching node;

control logic configured to control the first switch and the second switch according to an operating frequency to generate an AC power signal from a DC power signal; and

a resonant tank operably coupled to the first switching node of the bridge inverter, the resonant tank configured to receive the AC power signal and generate an electromagnetic field responsive thereto.

2. The wireless power transmitter of claim 1, wherein the bridge inverter includes a full bridge inverter.

3. The wireless power transmitter of claim 2, wherein the bridge inverter further includes:

a third switch and a fourth switch coupled together with a second switching node therebetween; and

a second capacitor coupled to the second switching node.

4. The wireless power transmitter of claim 3, wherein the resonant tank is operably coupled to the second switching node of the bridge inverter.

5. The wireless power transmitter of claim 4, wherein the resonant tank includes at least one resonant capacitor operably coupled with the transmit coil between the first switching node and the second switching node.

6. The wireless power transmitter of claim 3, wherein capacitance for each of the first capacitor and the second capacitor is within a range of values from 100 pF to 100 nF.

7. The wireless power transmitter of claim 3, wherein:

the first capacitor is coupled between the first switching node and ground; and

the second capacitor is coupled between the second switching node and ground.

8. The wireless power transmitter of claim 3, wherein:

the first capacitor is coupled between the first switching node and a power supply; and

the second capacitor is coupled between the second switching node and ground.

9. The wireless power transmitter of claim 3, wherein:

the first capacitor is coupled between the first switching node and a power supply; and

the second capacitor is coupled between the second switching node and the power supply.

10. The wireless power transmitter of claim 3, wherein:

the first capacitor is coupled between the first switching node and ground; and

the second capacitor is coupled between the second switching node and a power supply.

11. The wireless power transmitter of claim 1, wherein the first switch is a p-channel transistor, and the second switch is an n-channel transistor.

12. The wireless power transmitter of claim 1, wherein the bridge inverter includes a half-bridge inverter.

13. The wireless power transmitter of claim 1, wherein the control logic is further configured to implement a break-before-make time that is greater than or equal to a rate of change of the first switching voltage.

14. A method of operating a wireless power transmitter, the method comprising:

operating a first switch and a second switch of a bridge inverter according to an operating frequency to generate an AC signal from a DC signal, the first switch and the second switch having a first capacitor coupled at a first switching node therebetween; and

generating a wireless power signal through a resonant capacitor and a transmit coil coupled to the first switching node.

15. The method of claim 14, wherein operating the first switch and the second switch includes disabling the first switch and enabling the second switch at times that are separated by a break-before-make time.

16. The method of claim 14, wherein operating the first switch and the second switch of the bridge inverter includes generating a first switching voltage on the first switching node having a rate of change that is responsive to current flowing through the first capacitor.

17. The method of claim 14, further comprising operating a third switch and a fourth switch of the bridge inverter according to the operating frequency to generate the AC signal from the DC signal, the third switch and the fourth switch having a second capacitor coupled at a second switching node therebetween.

18. A method of making a wireless power transmitter, the method comprising:

coupling at least one capacitor to at least one switching node of a bridge inverter of a wireless power transmitter; and

coupling at least one resonant capacitor and at least one transmit coil to the at least one switching node.

19. The method of claim 18, wherein coupling the at least one capacitor to the at least one switching node includes:

coupling a first capacitor to a first switching node of an FET pair; and

coupling a second capacitor to a second switching node of another FET pair.

20. The method of claim 19, wherein:

coupling the first capacitor to the first switching node of an FET pair includes coupling the first capacitor between the first switching node and one of a power supply terminal and ground; and

coupling the second capacitor to the second switching node of another FET pair includes coupling the second capacitor between the second switching node and one of the power supply terminal and ground.