Protection of switched capacitor power converter

• US 8,619,445 B1
• Filed: 03/15/2013
• Issued: 12/31/2013
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: pSemi Corporation (Murata Manufacturing Co Limited)
• Original Assignee: Arctic Sand Technologies, Inc. (Murata Manufacturing Co Limited)
• Inventors: Giuliano, David M., Szczeszynski, Gregory, Low, Aichen, Summit, Jeff, Blyde, Oscar
• Primary Examiner(s): Tran, Nguyen
• Application Number:
  US13/838,681
• Time in Patent Office: 291 Days
• Field of Search: 363/59, 363/60, 307/109, 307/110, 327/535, 327/536
• US Class Current: 363/59
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps
• CPC Class Codes: H02M 3/073 Charge pumps of the Schenkel-type
• CPC Class Codes: H02M 3/075 including a plurality of stages and two sets of clock signals, one set for the odd and one set for the even numbered stages

Abstract

Transient or fault conditions for a switched capacitor power converter are detected by measuring one or more of internal voltages and/or currents associated with switching elements (e.g., transistors) or phase nodes, or voltages or currents at terminals of the converter, and based on these measurements detect that a condition has occurred when the measurements deviate from a predetermined range. Upon detection of the condition fault control circuitry alters operation of the converter, for example, by using a high voltage switch to electrically disconnect at least some of the switching elements from one or more terminals of the converter, or by altering timing characteristics of the phase signals.

Claims

1. A switched capacitor power converter comprising:

a first terminal for coupling to a first external circuit at substantially a high voltage;

a second terminal for coupling to a second external circuit at substantially a low voltage lower than the high voltage, wherein in operation of the power converter charge passes on a charge transfer path between the first terminal and the second terminal;

a plurality of semiconductor switch elements, including

a first set of switch elements on the charge transfer path between the first terminal and the second terminal, wherein no switch element in the first set of switch elements is connected in series with either the first terminal or the second terminal to carry substantially all the current passing through said terminal, and wherein each switch element in the first set of switch elements is configured to form a controllable charge transfer path between a corresponding subset of a plurality of capacitors, and

a second set of switch elements configured to form electrical connection of at least some of the capacitors to alternating reference voltages,

wherein said plurality of switch elements are configured to form said interconnections in successive states in operation;

measurement circuitry configured to measure a voltage and/or a current characteristic of one or more switch elements of the first set of switch elements or the second set of switch elements; and

fault control circuitry coupled to the measurement circuitry configured to alter operation of the power converter upon detection of a condition determined when the measured characteristics of the switch elements deviate from a predetermined range of said characteristics.

2. The switched capacitor power converter of claim 1 wherein the plurality of switch elements further includes:

a third set of switch elements on the charge transfer path between the first terminal and the second terminal connected in series with either the first terminal or the second terminal.

3. The switched capacitor power converter of claim 1 wherein the second set of switch elements include switch elements that form electrical connection of at least some of the capacitors to the low voltage terminal during some states of operation.

4. The switched capacitor power converter of claim 1 wherein the stages of operation comprise a repeated sequence of clocked stages.

5. The switched capacitor power converter of claim 1 further comprising the plurality of capacitors, each capacitor having a terminal coupled to a terminal of at least one switch element of the plurality of switch elements.

6. The switched capacitor converter of claim 5 wherein the capacitors and switch elements are integrated in a monolithic device.

7. The switched capacitor power converter of claim 1 where the converter comprises a Dickson charge pump.

8. The switched capacitor power converter of claim 1 wherein the voltage and/or current characteristics of the one or more switch elements belong to a group consisting of:

a voltage across terminals of a switch element of the first set of switch elements;

a current through a switch element of the first set of switch elements;

a voltage at a junction between a switch element of the first set of switch elements and a capacitor of the plurality of capacitors;

a voltage across terminals of a capacitor of the plurality of capacitors coupled to the switch element;

a voltage at a junction between a switch element of the second set of switch elements and a capacitor of the plurality of capacitors; and

a current through a switch element of the first set of switch elements.

9. The switched capacitor power converter of claim 1 wherein the voltage and/or current characteristic of the switch element comprises a voltage across terminals of the switch element.

10. The switched capacitor power converter of claim 1 wherein the voltage and/or current characteristic of the switch element comprises a current through the switch element.

11. The switched capacitor power converter of claim 1 wherein the voltage and/or current characteristic of the switch element comprises a voltage at a terminal of the switch element.

12. The switched capacitor power converter of claim 1 wherein the voltage and/or current characteristic of the switch element comprises a voltage across terminals of a capacitor of the plurality of capacitors coupled to the switch element.

13. The switched capacitor power converter of claim 1 wherein the switch elements of the second set of switch elements form a phase generator, and wherein the voltage and/or current characteristic of the switch element comprises a voltage and/or current supplied by the phase generator.

14. The switched capacitor power converter of claim 1 wherein each of the semiconductor switch elements comprises a FET transistor for coupling at least two of the capacitors.

15. The switched capacitor power converter of claim 14 wherein at least some of the semiconductor switch elements comprise a network of multiple FET transistors.

16. The switched capacitor power converter of claim 1 wherein at least some of the switch elements of the first set of switch elements or the second set of switch elements have a maximum voltage rating less than the high voltage.

17. The switch capacitor power converter of claim 16 wherein at least some of the switch elements of the first set of switch elements or the second set of switch elements have a maximum voltage rating less than the difference between the high voltage and the low voltage.

18. The switch capacitor power converter of claim 17 wherein at least some of the switch elements of the first set of switch elements or the second set of switch elements have a maximum voltage rating no greater than a fraction 1/N, N>

1, of the difference between the high voltage and the low voltage.

19. The switched capacitor power converter of claim 1 wherein the fault control circuitry comprises one or more switches each having maximum voltage rating greater than the voltage rating of at least some of the plurality of switches, the one or more switches being configured to electrically disconnecting or limit current flow through at least some switch elements of the plurality of switch elements.

20. The switched capacitor power converter of claim 19 wherein the one or more switches comprise a switch coupled directly to the first terminal.

21. The switched capacitor power converter of claim 19 wherein the one or more switches comprise a switch coupled between two switch elements of the plurality of switch elements.

22. The switched capacitor power converter of claim 1 wherein the fault control circuitry is configured to modify the characteristics of the phases upon detection of the condition.

23. The switched capacitor power converter of claim 22 wherein the characteristics of the phases belong to a group consisting of:

a duty cycle of clocked phases;

a clocking frequency of the phases; and

a skipping of one or more clock cycles of clocked phases.