Ultrafast single actuator electromechanical disconnect switch

Abstract

An ultrafast electromechanical switch having a drive mechanism comprising two non-movable contacts connected to electrical feedthroughs, one actuator and one movable contact. The provided ultrafast electrical (e.g., transfer, disconnect, etc.) switch is simple, compact, clean, exhibits ultralow loss, does not require high energy to operate and is capable of being automatically reset.

Claims

1. An electrical switch, comprising: a first electrical feedthrough disposed through an insulating medium, said first electrical feedthrough connected to a first non-movable electrical contact and said first non-movable electrical contact coupled to said insulating medium; a second electrical feedthrough disposed through the insulating medium, said second electrical feedthrough connected to a second non-movable electrical contact and said second non-movable electrical contact coupled to said insulating medium; a static gap disposed between said first non-movable contact and said second non-movable contact; an actuator aligned with said static gap but positioned at a spaced distance away from said first and second non-movable contacts; said actuator being a piezoelectric actuator or a magnetostrictive actuator; a movable contact directly or indirectly coupled to said actuator and aligned with said static gap, said movable contact contacting said first and second non-movable contacts simultaneously to complete a series between said first and second non-movable contacts, wherein when said actuator is prompted, said movable contact shifts away from said first and second non-movable contacts, such that a variable gap is formed between said movable contact and said first and second non-movable contacts, thus breaking or disconnecting said series between said first and second non-movable contacts, said actuator also releasing contact pressure between said movable contact and said first and second non-movable contacts, wherein when said actuator is idle or unprompted, said movable contact is contacting said first and second non-movable contacts, an electrical circuit is closed within said electrical switch, such that a current flows along a path of travel within said electrical switch across said first non-movable contact, said movable contact and said second non-movable contact.

2. An electrical transfer or disconnect switch as in claim 1, further comprising: a switching chamber that encloses at least said insulating medium, said first non-movable contact, said second non-movable contact, said movable contact, and said actuator, said switching chamber containing vacuum or pressurized gas.

3. An electrical transfer or disconnect switch as in claim 1, further comprising: said insulation medium further disposed between said actuator and said movable contact to electrically insulate said actuator and said movable contact from each other.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a fuller understanding of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which:

(2) FIG. 1 depicts an embodiment of the present invention utilizing two non-amplified piezoelectric actuators.

(3) FIG. 2 is a schematic depicting an embodiment of the current invention using a single amplified piezoelectric actuator.

(4) FIG. 3 depicts the embodiment of FIG. 2 implemented within a switching chamber.

(5) FIG. 4 is an isometric view of the embodiment of FIGS. 2-3.

DETAILED DESCRIPTION OF THE INVENTION

(6) In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings, which form a part thereof, and within which are shown by way of illustration specific embodiments by which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the invention.

(7) In an embodiment, the current invention is an ultrafast electromechanical switch having a drive mechanism integrated into a switching chamber. The present invention makes use of the ultrafast response times of electromechanical actuators (e.g., piezoelectric or magnetostrictive actuator) and integrates them inside a switching chamber so that their force can be applied directly to separate the contacts, creating a compact ultrafast disconnect switch. It is contemplated herein that the drive mechanism can be a piezoelectric actuator, magnetostrictive actuator, or any other drive mechanism known by one of ordinary skill in the art. The integration of the drive mechanism in the present invention allows for significantly faster contract travel and therefore faster switching operation than would be otherwise capable. The switching chamber is designed to enclose the switching mechanism within a self-contained environment, which includes, but is not limited to, a high-pressure gas or vacuum environment. Other suitable environments are contemplated herein as well.

(8) In certain embodiments, the present invention utilizes a vacuum to enclose the switching chamber. The vacuum provides a benign environment resulting in zero oxidation and allows use of reactive materials, including but not limited to, aluminum. The vacuum also decreases contact wear due to the lack of electric arcs. Such a design would greatly improve the working life of a switching chamber. Other suitable insulation mediums, such as liquids for example, are contemplated herein. Choice of insulation medium may depend on voltage and current levels desired among other factors.

(9) In an embodiment, the invention can be implemented in a manner that significantly improves its performance, particularly with regards to voltage rating and current carrying capability (i.e., power rating).

(10) In an embodiment that may become more apparent in Example 1 infra, the current invention includes a piezoelectric stack, such that when an electric field is applied internally, the stack expands or lengthens linearly to separate electrical contacts from each other or to cause electrical contacts to contact each other. The very small distance that electrical contacts must move/shift may limit the voltage range but simultaneously allows for very high forces, which is suitable for high current levels.

(11) In another embodiment that may become more apparent in Example 2 infra, the piezoelectric stack is configured in a shell that is relatively malleable and can be about as thick as the shell itself. The stack is present in the long axis of the shell. When the stack expands due to an internally applied electric field, the circumference of the shell would remain similar, though the short sides of the shell would contract to pull the contacts inward and disconnect the series. Because the shell is elliptical or ovular in nature, the shell can contract as much as the stack expands. Because of this, some of the higher forces may be lost, but because of the more compact separation, the device can be designed for higher voltage, lower current applications.

(12) Any combination of the following examples (or elements thereof) is also contemplated herein by the current invention.

Example 1

(13) In an embodiment, as shown in FIG. 1, the current invention is a switching mechanism, generally denoted by the reference numeral 10, that includes an enclosed switching chamber created with the use of flange (12) and vessel (14). Electrical feedthroughs (16, 18) pass through flange (12) into the switching chamber. On the outside of the switching chamber, the conductors (not shown in this figure) that pass through feedthroughs (16, 18) are used to connect to the two electrical poles of the system that will be separated by the disconnect. Inside the switching chamber, feedthroughs (16, 18) connect to non-movable electrical contacts (20a, 20b), once feedthroughs (16, 18) have passed through the block of insulating material (22). Insulating material (22) serves to electrically insulate switching mechanism (10) from the surrounding walls of vessel (14) and flange (12). Non-movable contact (20c) is coupled to insulating material (22) and is positioned between non-movable contacts (20a, 20b), such that static gap (21a) exists between non-movable contacts (20a, 20c) and static gap (21b) exists between non-movable contacts (20b, 20c).

(14) Switching mechanism (10) further includes piezoelectric actuators (24, 26) directly or indirectly coupled to two movable contacts (28, 30). Piezoelectric actuators (24, 26) and movable contacts (28, 30) can be electrically insulated from each other with insulators (32, 34) disposed therebetween, as seen in FIG. 1. Actuators (24, 26) each have a contracted position and an extended position. FIG. 1 shows actuators (24, 26) being inactivated/unpowered and disposed in at least a partially contracted position, where movable contacts (28, 30) do not physically contact non-movable contacts (20a, 20b, 20c).

(15) When actuator (24) is at its full extension (i.e., when actuator (24) is powered), movable contact (28) is physically pressed up against non-movable contacts (20a, 20c). When actuator (26) is at its full extension (i.e., when actuator (26) is powered), movable contact (30) is physically pressed up against non-movable contacts (20b, 20c) (not shown in this figure but shown in FIG. 2). This creates a completed electrical pathway between the electrodes. When complete, the electrical pathway would flow as follows: electrical feedthrough (16), non-movable contact (20a), movable contact (28), non-movable contact (20c), movable contact (30), non-movable contact (20b), and electrical feedthrough (18).

(16) When actuators (24, 26) are at their full or at least partial contraction (i.e., when actuators (24, 26) inactivated, unpowered, or otherwise unprompted), variable gap (29a) exists between non-movable contacts (20a, 20c) and movable contact (28), and variable gap (29b) exists between non-movable contacts (20b, 20c) and movable contact (30). The sum of variable gaps (29a, 29b) may be used to determine the voltage withstand capability (e.g., up to about 2 kV) of switching mechanism (10) (e.g., disconnect switch) when open (actuators in full contraction).

(17) Piezoelectric actuators (24, 26) can be controlled with control signal wires (32) that pass through the control wire feed-through (35).

(18) Vessel (14) can be evacuated or pressurized through side port (36) with isolation valve (38).

(19) With this configuration, all four (4) contact points (i.e., movable contact (28) and non-movable contact (20a), movable contact (28) and non-movable contact (20c), movable contact (30) and non-movable contact (20b), and movable contact (30) and non-movable contact (20c)) are electrically in series and operate at the same time, thus providing four (4) times the standoff voltage while in open position.

(20) With the ultrafast response times of the integrated piezoelectric actuators (24, 26) combined with creation of the multiple gaps (29a, 29b) inside a sealed switching container (flange (12), vessel (14)) containing vacuum or pressurized gas, switching mechanism (10) provides the switching time and voltage withstand capability to fill a void in options that has existed for applications until now. In particular, switching mechanism (10) can be extremely useful in the design of hybrid circuit breaker applications in medium voltage AC and DC electrical distribution systems.

Example 2

(21) FIGS. 2-4 depict an alternate embodiment of the current invention, generally denoted by the reference numeral 50. Switching mechanism 50 can be based on the use of piezoelectric actuator (52) with elliptical shell (54) outside of piezoelectric actuator (52). The planar geometry allows for series and parallel connections to increase voltage withstand and current ratings with only minimum increase in size.

(22) Elliptical shell actuator (54) can be used to drive (i.e., open and close) movable contacts (56, 58) of switching mechanism (50) on each side of elliptical shell (54) in a very fast manner, while still providing enough contact pressure for low ohmic contact resistance in closed state. At the same time, elliptical shell actuator (54) also allows for high voltage withstand capability in open state.

(23) Movable contacts (56, 58) can be characterized as follows:

(24) No electric arcs.fwdarw.little contact wear expected

(25) Vacuum is benign environment.fwdarw.no oxidation, i.e., use of reactive materials (such as aluminum) possible

(26) Contact surface area vs. pressure/force, as described in H. Bhme, (2005). Mittelspannungstechnik

(27) Generally, switching mechanism (50) (e.g., disconnect switch) is based on a sheet (e.g., rectangular) of insulating material (60), optionally not much longer nor wider than the actuator itself in order to conserve material and make the implementation as compact as possible. The sheet of insulating material (60) can have its center area removed to accommodate actuator (52). The conductor runs on three sides along the edge of insulating material (60) where non-movable contacts (62, 64, 66) can be seen. Non-movable contact (66) can be positioned on three sides of insulating material (60), as seen in FIG. 2, and as such still be disposed between non-movable contact (62) and non-movable contact (64).

(28) The long sides of actuator ellipse (54) can be held flexibly in place by slots (68a, 68b) in the insulator sheet (60). The short sides of actuator ellipse (54) can be deemed mounting plates (55a, 55b) in that mounting plates (55a, 55b) of actuator (52) cause movement of movable contacts (56, 58) in response to actuation of actuator ellipse (54) (i.e., mounting plates (55a, 55b) pull movable contacts (56, 58) inwards and away from non-movable contacts (62, 64, 66)). Mounting plates (55a, 55b) can be attached to stems (70, 72) cut into the insulating sheet (60). FIGS. 2-3 show actuator (52) in a fully extended position (i.e., actuator (52) is not powered/activated), such that movable contact (56) is physically pressed up against non-movable contacts (62, 66) and movable contact (58) is physically pressed up against non-movable contacts (64, 66). This can be compared to FIG. 1, where gaps (29a, 29b) exist, showing that actuators (24, 26 in FIG. 1) have been powered/activated. The operation is substantially similar, where actuator (52) has a contracted position when powered and an extended position when not powered. Accordingly, similar gaps (similar to variable gaps (29a, 29b) in FIG. 1) would exist between movable contacts (56, 58) and non-movable contacts (62, 64, 66). When these variable gaps exist as in FIG. 1, the electrical series is disconnected or broken. Alternatively, when movable contacts are physically pressed up against non-movable contacts (62, 64, 66) as in FIGS. 2-3, the electrical series is intact.

(29) Four (4) optional precision adjustment screws (74, 76, 78, 80) can be coupled to non-movable contacts (62, 64, 66) and insulation material (60) to allow for adjustment of the contact pressure.

(30) With this configuration, all four (4) contact points (i.e., movable contact (56) and non-movable contact (62), movable contact (56) and non-movable contact (66), movable contact (58) and non-movable contact (64), and movable contact (58) and non-movable contact (66)) are electrically in series and operate at the same time, thus providing four (4) times the standoff voltage while in open position.

(31) As can be seen in FIG. 3, similar to the example of FIG. 1, switching mechanism (50) can be located in vessel (82) with flange (84) that features two power feedthroughs (86, 88) and one control wire signal feedthrough (90). Piezoelectric actuator (52, 54) can be controlled with control signal wires (89) that pass through the control wire feed-through (90).

(32) Vessel (82) can be evacuated or pressurized through side port (92) with isolation valve (94). If vessel (82) contains a vacuum environment, the vacuum can be characterized as follows:

(33) Breakdown by field emission

(34) Theoretical limit: work function approx. 4.5 eV (equiv. 1000 kV/mm)

(35) Practical limit: 1-30 kV/mm (depending on surface quality, material, and temperature)

Glossary of Claim Terms

(36) Actuator: This term is used herein to refer to a mechanism that causes two or more electrical contacts to contact each other or separate from each other by changing the position or one of the electrical contacts.

(37) Electrical feedthrough: This term is used herein to refer to a conductor that carries a signal and/or power through an enclosure or chamber.

(38) Electrical transfer or disconnect switch: This term is used herein to refer to an electrical component used to break an electrical circuit by interrupting the current and/or diverting the current from one conductor to another. For example, a transfer switch is an electrical switch that transfers a load between two sources. A disconnect switch is an electrical switch that completely halts the current in the circuit and/or diverts it to another source.

(39) Insulating medium: This term is used herein to refer to a material or substance that does not permit the transfer of electricity therethrough.

(40) Mounting plate: This term is used herein to refer to a component of an actuator (e.g., piezoelectric actuator) that, when prompted, exerts a force on the movable contacts to create a gap between the movable contacts and non-movable contacts, thus disconnecting the electrical series between the non-movable contacts, and ultimately cause the movable contacts to no longer physically contact the non-movable contacts.

(41) Movable contact: This term is used herein to refer to a component of an electrical circuit, where the component has a variable position, and when it contacts another electrical contact, electrical current can be passed therebetween.

(42) Non-movable electrical contact: This term is used herein to refer to a component of an electrical circuit, where the component is fixed in place and when contacted by another electrical contact, electrical current can be passed therebetween.

(43) Piezoelectric actuator: This term is used herein to refer to a mechanism that causes two or more electrical contacts to contact each other or separate from each other in response to the generation of elimination of a voltage caused by an applied mechanical stress.

(44) Precision adjustment screw: This term is used herein to refer to a device that is capable of altering the amount of spacing between two or more electrical components and/or regulating the pressure that two or more components exert on each other when contacting each other.

(45) Static gap: This term is used herein to refer to a fixed spacing between two electrical components.

(46) Switching chamber: This term is used herein to refer to any enclosure with a controlled environment that houses a switching mechanism and components thereof.

(47) Variable gap: This term is used herein to refer to changeable spacing between two or more electrical components.

(48) The advantages set forth above, and those made apparent from the foregoing description, are efficiently attained. Since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

(49) It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention that, as a matter of language, might be said to fall therebetween.