Micro-electromechanical system relay circuit

Patent metadata

Field	Value
Publication number	US-10068733-B2
Application number	US-201514919797-A
Country	US
Kind code	B2
Filing date	Oct 22, 2015
Priority date	Oct 22, 2015
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

A switching system includes a MEMS switching circuit having a MEMS switch and a driver circuit, and an auxiliary circuit coupled in parallel with the MEMS switching circuit that comprises solid state switching circuitry. A control circuit in communication with the MEMS switching circuit and the auxiliary circuit performs selective switching of a load current towards the MEMS switching circuitry and the auxiliary circuit, with the control circuit programmed to transmit a control signal to the driver circuit to cause the MEMS switch to actuate to an open or closed position across a switching interval, activate the auxiliary circuit during the switching interval when the MEMS switch is switching between the open and closed positions, and deactivate the auxiliary circuit upon reaching the open or closed position after completion of the switching interval, such that the load current selectively flows through the MEMS switch and the solid state switching circuitry.

First claim

What is claimed is:

1. A switching system, comprising:
a micro-electromechanical system (MEMS) switching circuit including a MEMS switch and a driver circuit;
an auxiliary circuit coupled in parallel with the MEMS switching circuit, the auxiliary circuit comprising solid state switching circuitry; and
a control circuit in communication with the MEMS switching circuit and the auxiliary circuit to perform selective switching of a load current towards the MEMS switching circuit and the auxiliary circuit, the control circuit programmed to:
transmit a control signal to the driver circuit to cause the MEMS switch to actuate to an open or closed position across a switching interval;
activate the auxiliary circuit during the switching interval when the MEMS switch is switching between the open and closed positions, such that at least a portion of the load current flows toward the solid state switching circuitry and the MEMS switch withstands a full system voltage when open; and
deactivate the auxiliary circuit upon the MEMS switch reaching the open or closed position after completion of the switching interval, such that the load current flows through the MEMS switch when closed.

2. The switching system of claim 1 wherein activation of the auxiliary circuit during the switching interval limits the voltage across the MEMS switch to a voltage level below a pre-determined voltage threshold.

3. The switching system of claim 2 wherein the pre-determined voltage threshold comprises a hot-switching voltage threshold of approximately 10 V.

4. The switching system of claim 2 wherein the pre-determined voltage threshold comprises a hot-switching voltage threshold of approximately 1 V.

5. The switching system of claim 2 wherein, when the MEMS switch is actuated from the open position to the closed position, the control circuit is programmed to:
activate the auxiliary circuit to cause at least a portion of the load current to flow toward the solid state switching circuitry; and
subsequent to the activation of the auxiliary circuit, transmit a control signal to the driver circuit to cause the MEMS switch to actuate to the closed position, with the voltage across the MEMS switch being clamped at a level below the pre-determined voltage threshold due to activation of the auxiliary circuit.

6. The switching system of claim 2 wherein, when the MEMS switch is actuated from the closed position to the open position, the control circuit is further programmed to:
activate the auxiliary circuit to cause at least a portion of the load current to flow toward the solid state switching circuitry; and
subsequent to the activation of the auxiliary circuit, transmit a control signal to the driver circuit to cause the MEMS switch to actuate to the open position, with the voltage across the MEMS switch being clamped at a level below the pre-determined voltage threshold due to activation of the auxiliary circuit.

7. The switching system of claim 1 wherein the switching interval during which the auxiliary circuit is activated is approximately 10 microseconds or less in duration.

8. The switching system of claim 1 further comprising first and second control terminals coupled to the control circuit to provide On and Off signals thereto;
wherein the control circuit is programmed to:
send a first control signal to the driver circuit upon receipt of an On signal from the control terminals, the first control signal causing the driver circuit to apply a high voltage to a gate of the MEMS switch to actuate the MEMS switch to the closed position; and
send a second control signal to the driver circuit upon receipt of an Off signal from the control terminals, the second control signal causing the driver circuit to apply a low voltage to a gate of the MEMS switch to actuate the MEMS switch to the open position.

9. The switching system of claim 1 wherein the solid state switching circuitry comprises a plurality of MOSFETs, with one or more of the plurality of MOSFETs conducting current therethrough when the auxiliary circuit is activated.

10. The switching system of claim 1 wherein the MEMS switching circuitry, the auxiliary circuit and the controller collectively form one of a MEMS relay circuit and a protection MEMS circuit.

11. A micro-electromechanical system (MEMS) relay circuit comprising:
a MEMS switching circuit including:
a MEMS switch selectively moveable between an open position and a closed position, the MEMS switch being moved between the open and closed positions within a switching interval; and
a driver circuit configured to provide a drive signal to cause the MEMS switch to move between the open and closed positions;

an auxiliary circuit in operable communication with the MEMS switching circuit to selectively limit a voltage across the MEMS switch; and
a control circuit in communication with the MEMS switching circuit and the auxiliary circuit and programmed to:
send control signals to the driver circuit to cause the driver circuit to move the MEMS switch from the open position to the closed position or from the closed position to the open position within the switching interval; and
selectively activate the auxiliary circuit for a duration of the switching interval, so as to clamp the voltage across the MEMS switch below a pre-determined threshold voltage when moving from the open position to the closed position or from the closed position to the open position.

12. The MEMS relay circuit of claim 11 wherein, in activating the auxiliary circuit, the control circuit is programmed to operate at least one of a plurality of solid state switches in the auxiliary circuit in an On mode to conduct current therethrough.

13. The MEMS relay circuit of claim 12 wherein operating at least one of the plurality of solid state switches in the auxiliary circuit in the On mode causes at least a portion of a load current provided to the MEMS relay circuit to flow toward the plurality of solid state switches, thereby lowering a level of the load current across the MEMS switch and the corresponding voltage across the MEMS switch.

14. The MEMS relay circuit of claim 13 wherein, in activating the auxiliary circuit, the control circuit is programmed to activate the auxiliary circuit immediately prior to initiation of the switching interval, such that the at least a portion of the load current provided to the MEMS relay circuit is caused to flow toward the plurality of solid state switches prior to movement of the MEMS switch between the open and closed positions.

15. The MEMS relay circuit of claim 12 wherein the plurality of solid state switches in the auxiliary circuit is arranged in parallel with the MEMS switch.

16. The MEMS relay circuit of claim 11 wherein the pre-determined voltage threshold comprises a hot-switching voltage threshold of approximately 10 V.

17. The MEMS relay circuit of claim 11 wherein the pre-determined voltage threshold comprises a hot-switching voltage threshold of approximately 1 V.

18. The MEMS relay circuit of claim 11 wherein the switching interval during which the auxiliary circuit is activated is approximately 10 microseconds or less in duration.

19. The MEMS relay circuit of claim 11 wherein the auxiliary circuit remains in a deactivated state during periods when the MEMS switch remains in the open position or the closed position.

20. A method of controlling a micro-electromechanical system (MEMS) relay circuit that includes a MEMS switching circuit, an auxiliary circuit and a control circuit, the method compr

Assignees

• Gen Electric

Inventors

• Liu Yanfei
• Claydon Glenn Scott
• Keimel Christopher Fred
• Giovanniello Jr Christian Michael

Classifications

• H01H47/02 Primary

  for modifying the operation of the relay · CPC title

• H01H59/0009

  making use of micromechanics · CPC title

• H01H2071/008

  Protective switches or relays using micromechanics · CPC title

• H01H9/542 Primary

  Contacts shunted by static switch means · CPC title