THREE-QUARTER BRIDGE POWER CONVERTERS FOR WIRELESS POWER TRANSFER APPLICATIONS AND OTHER APPLICATIONS

• US 20110211380A1
• Filed: 02/25/2011
• Published: 09/01/2011
• Est. Priority Date: 03/01/2010
• Status: Active Grant

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Brown, James Steven
• Granted Patent: US 8,779,745 B2
• Time in Patent Office: Days
• US Class Current: 363/131
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02M 3/01 Resonant DC/DC converters
• CPC Class Codes: H02M 3/33561 having more than one ouput with independent control
• CPC Class Codes: H02M 3/33569 having several active switching elements H02M3/3353 takes precedence

Abstract

A three-quarter bridge power converter includes a first switch configured to selectively couple a switch node to a higher voltage. The power converter also includes a second switch configured to selectively couple the switch node to a lower voltage. The power converter further includes a third switch configured to selectively cause a third voltage to be provided to the switch node when the first and second switches are not coupling the switch node to the higher and lower voltages. The third switch may be configured to selectively couple the switch node to an energy storage or energy source, such as a capacitor. The third switch may also be configured to selectively couple an energy storage or energy source to ground, where the energy storage or energy source is coupled to the switch node.

Claims

1. A three-quarter bridge power converter comprising:

a first switch configured to selectively couple a switch node to a higher voltage;

a second switch configured to selectively couple the switch node to a lower voltage; and

a third switch configured to selectively cause a third voltage to be provided to the switch node when the first and second switches are not coupling the switch node to the higher and lower voltages.

2. The power converter of claim 1, wherein the third switch is configured to selectively couple the switch node to an energy storage or energy source.

3. The power converter of claim 2, wherein the third switch is configured to selectively couple the switch node to a capacitor.

4. The power converter of claim 1, wherein the third switch is configured to selectively couple an energy storage or energy source to ground, the energy storage or energy source coupled to the switch node.

5. The power converter of claim 1, further comprising:

a circuit coupled to the switch node and configured to provide power to a load, the circuit comprising at least one coil or transformer winding.

6. The power converter of claim 5, further comprising at least one of:

a single-ended voltage sensor configured to measure a voltage across the coil or transformer winding; and

a single-ended current sensor configured to measure a current through the coil or transformer winding.

7. The power converter of claim 1, further comprising:

a control circuit configured to generate control signals for the first, second, and third switches.

8. The power converter of claim 7, wherein the control circuit comprises:

a phase accumulator configured to receive a value associated with a drive frequency;

an adder configured to add an output of the phase accumulator and a value associated with a drive duty factor;

at least one extraction unit configured to identify a most significant bit in an output of the phase accumulator and a most significant bit in an output of the adder; and

combinatorial logic configured to generate the control signals using the most significant bits.

9. The power converter of claim 1, wherein:

the higher voltage comprises a supply voltage;

the lower voltage comprises ground; and

the third voltage is approximately one-half of the supply voltage.

10. A system comprising:

a load; and

a three-quarter bridge power converter configured to provide power to the load, the power converter comprising;

a first switch configured to selectively couple a switch node to a higher voltage;

a second switch configured to selectively couple the switch node to a lower voltage; and

a third switch configured to selectively cause a third voltage to be provided to the switch node when the first and second switches are not coupling the switch node to the higher and lower voltages.

11. The system of claim 10, wherein the third switch is configured to selectively couple the switch node to an energy storage or energy source.

12. The system of claim 11, wherein the third switch is configured to selectively couple the switch node to a capacitor.

13. The system of claim 10, wherein the third switch is configured to selectively couple an energy storage or energy source to ground, the energy storage or energy source coupled to the switch node.

14. The system of claim 10, wherein the power converter further comprises:

a circuit coupled to the switch node and configured to provide power to a load, the circuit comprising at least one coil or transformer winding.

15. The system of claim 14, wherein the power converter further comprises at least one of:

a single-ended voltage sensor configured to measure a voltage across the coil or transformer winding; and

a single-ended current sensor configured to measure a current through the coil or transformer winding.

16. The system of claim 10, further comprising:

a control circuit configured to generate control signals for the first, second, and third switches.

17. The system of claim 16, wherein the control circuit comprises:

a phase accumulator configured to receive a value associated with a drive frequency;

an adder configured to add an output of the phase accumulator and a value associated with a drive duty factor;

at least one extraction unit configured to identify a most significant bit in an output of the phase accumulator and a most significant bit in an output of the adder; and

combinatorial logic configured to generate the control signals using the most significant bits.

18. The system of claim 10, wherein:

the three-quarter bridge power converter comprises a portion of a wireless power transmitter; and

the load comprises a wireless power receiver.

19. The system of claim 18, wherein the three-quarter bridge power converter is coupled to a matrix comprising multiple transmit coils or transformer windings.

20. A method comprising:

repeatedly coupling a switch node to a higher voltage and a lower voltage using first and second switches, respectively; and

selectively providing a third voltage to the switch node using a third switch when the first and second switches are not coupling the switch node to the higher and lower voltages.