JP2008310972A - Soft switching based on microelectromechanical systems - Google Patents

Abstract

A system (10) is provided.
The system (10) includes a detection circuit (14) configured to detect the occurrence of a zero crossing of an AC power supply voltage (36) or an AC load current (42). The system also includes a switching circuit (12) coupled to the detection circuit (14) and comprising a microelectromechanical system switch (20). In addition, the system (10) is coupled to the detection circuit (14) and the switching circuit (12) and is responsive to the detected zero crossing of the alternating power supply voltage (36) or the alternating load current (42) to the microelectromechanical system. A control circuit (16) configured to provide arc-free switching of the switch (20) is included.
[Selection] Figure 2

Description

  The present invention relates generally to switching elements, and more particularly to switching elements based on microelectromechanical systems.

Conventionally, an electromechanical contactor is used in a control device, and the electromechanical contactor can handle switching of current up to its breaking capacity. Electromechanical contactors also find use in power systems for switching current. Usually, however, the fault current in the power system is greater than the breaking capability of the electromechanical contactor. Therefore, to use an electromechanical contactor for power system applications, a series that operates quickly enough to interrupt the fault current before the contactor opens at all current values that exceed the contactor's interrupt capability. It is desirable to protect the contactor from damage by assisting with the element.
US Patent Application Publication No. 2005/0146814

  Conventional solutions contemplated to facilitate the use of contactors in power systems include, for example, vacuum contactors, vacuum circuit breakers, and air break contactors. Unfortunately, a contactor such as a vacuum contactor is not easy to visually inspect because the contactor tip is sealed and sealed in a vacuumed casing. In addition, vacuum contactors are well suited to handle large motors, transformers, and capacitor switching, but are known to produce deleterious transient overvoltages, especially when the load is switched off. .

  Furthermore, electromechanical contactors generally use mechanical switches. However, these mechanical switches are relatively slow and often require predictive techniques to estimate the occurrence of a zero crossing tens of milliseconds before a switching event occurs. Such zero-cross prediction is prone to errors because many transients occur at this point.

  Briefly, according to aspects of the present technique, a system is presented. The system includes a detection circuit configured to detect an occurrence of a zero crossing of an AC power supply voltage or an AC load current. The system also includes a switching circuit coupled to the detection circuit and comprising a microelectromechanical system switch. The system further includes a control circuit coupled to the detection circuit and the switching circuit and configured to perform arcless switching of the microelectromechanical system switch in response to the detected zero crossing of the AC power supply voltage or AC load current. .

  According to another aspect of the present technique, a method is presented. The method includes detecting the occurrence of a zero crossing of an AC power supply voltage or an AC load current. The method further includes switching the current state of the microelectromechanical system switch in response to the detected zero cross, wherein the microelectromechanical system switch is responsive to the detected zero cross of the alternating load current to load circuit The micro electromechanical system switch is closed in an arc-free manner to complete the load circuit in response to a detected zero crossing of the AC power supply voltage. Become so.

  According to another aspect of the present technique, a method is presented. The method includes monitoring an AC power supply voltage or an AC load current in the switch array, the switch circuit comprising a plurality of switch modules coupled in series. The method further includes detecting the occurrence of a zero crossing of the AC load current or AC power supply voltage. The method also includes generating a trigger signal in response to the detected zero crossing, wherein the trigger signal is configured to facilitate switching of the current operating state of the microelectromechanical system switch. The method further includes switching the current state of each of the plurality of switch modules in response to the trigger signal.

  These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: .

  According to embodiments of the present invention, systems and methods for arcless switching based on microelectromechanical systems are described herein. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of various embodiments of the present invention. However, one of ordinary skill in the art appreciates that the embodiments of the invention may be practiced without these specific details, and that the invention is not limited to the embodiments shown and that the invention may be embodied in various alternative embodiments. It will be understood that In other instances, well-known methods, procedures and components will not be described in detail.

  Moreover, various operations may be described as multiple discrete steps performed to aid in understanding embodiments of the present invention. However, the order of description should not be understood to mean that these operations need to be performed in the order presented, nor should they be understood to be dependent on the order. Further, the phrase “in one embodiment” used repeatedly may or may not necessarily refer to the same embodiment. Finally, the terms “comprising”, “including”, “having” and the like used in the present application are synonymous unless otherwise specified.

  FIG. 1 shows a block diagram of an exemplary soft switching system 10 according to an aspect of the present invention. As shown in FIG. 1, soft switching system 10 includes a switching circuit 12, a detection circuit 14, and a control circuit 16 operatively coupled to one another. The detection circuit 14 is coupled to the switching circuit 12 and is a zero cross of an AC power supply voltage in the load circuit (hereinafter referred to as “power supply voltage”) or an AC current in the load circuit (hereinafter referred to as “load circuit current”). It can be configured to detect the occurrence. The control circuit 16 can be coupled to the switching circuit 12 and the detection circuit 14 and is responsive to a detected zero crossing of the AC power supply voltage or the AC load circuit current in one or more switches of the switching circuit 12. It can be configured to facilitate arc-free switching. In one embodiment, the control circuit 16 can be configured to facilitate arc-free switching of one or more MEMS switches that form at least a portion of the switching circuit 12.

  According to one aspect of the present invention, the soft switching system 10 can be configured to perform soft switching or point-on-wave switching, whereby one or more MEMS switches in the switching circuit 12 are connected to the switching circuit. The circuit can be closed when the voltage across 12 is zero or nearly zero, and can be opened when the current through the switching circuit 12 is zero or nearly zero. When the switch is closed, the switches are closed when the voltage across the switching circuit 12 is zero or nearly zero, thereby keeping the electric field between the contacts of the one or more MEMS switches low. Even when all the circuits are not closed at the same time, it is possible to prevent arcing before the contacts contact. Similarly, by opening the switch when the current through the switching circuit 12 is zero or nearly zero, the current of the last open switch in the switching circuit 12 falls within the design capability of the switch. A soft switching system 10 can be designed. As mentioned above, according to one embodiment, the control circuit 16 synchronizes the opening and closing of one or more MEMS switches in the switching circuit 12 with the occurrence of zero crossing of the AC power supply voltage or AC load circuit current. It can be configured to be.

  Referring to FIG. 2, a schematic diagram 18 of one embodiment of the soft switching system 10 of FIG. 1 is shown. According to the illustrated embodiment, schematic diagram 18 includes one example of switching circuit 12, detection circuit 14, and control circuit 16.

  For illustration purposes, only a single MEMS switch 20 is shown in FIG. 2, but the switching circuit 12 is nevertheless a plurality of MEMS, eg, depending on the current and voltage processing requirements of the soft switching system 10. A switch can also be included. In one embodiment, the switching circuit 12 can include a switch module that includes a plurality of MEMS switches coupled together in a parallel configuration to divide the current between the MEMS switches. In other embodiments, the switching circuit 12 can include an array of MEMS switches coupled in a series configuration to divide the voltage between the MEMS switches. In yet another embodiment, the switching circuit 12 is a MEMS switch module coupled together in a series configuration to divide the voltage between the MEMS switch modules and to divide the current between the MEMS switches in each module. Can be included. In one embodiment, one or more MEMS switches of the switching circuit 12 can be combined in a single package 28.

  The exemplary MEMS switch 20 can include three contacts. In one embodiment, the first contact can be configured as the drain 22, the second contact can be configured as the source 24, and the third contact can be configured as the gate 26. In one embodiment, the control circuit 16 can be coupled to the gate contact 26 to facilitate switching of the current state of the MEMS switch 20. Also, in some embodiments, a damping circuit 29 can be coupled in parallel with the MEMS switch 20 to delay the appearance of a voltage across the MEMS switch 20. Damping circuit 29 may include a snubber capacitor 30 and a snubber resistor 32 coupled in series with it, for example, as shown.

Further, as shown in FIG. 2, the MEMS switch 20 can be coupled in series with the load circuit 34. In the configuration contemplated herein, the load circuit 34 may include a voltage source V _SOURCE 36 and may include a representative load inductance L _LOAD 38 and a load resistor R _LOAD 40. In one embodiment, the voltage source V _SOURCE 36 (also referred to as an AC voltage source) can be configured to generate an AC power supply voltage and an AC load current I _LOAD 42.

As previously mentioned, the detection circuit 14 can be configured to detect the occurrence of zero crossing of the AC power supply voltage or the AC load current I _LOAD 42 in the load circuit 34. The AC power supply voltage can be detected using the voltage detection circuit 46, and the AC load current I _LOAD 42 can be detected using the current detection circuit 48. The AC power supply voltage and the AC load current can be detected, for example, continuously or at discrete periods.

The zero crossing of the power supply voltage can be detected using a comparator such as the zero voltage comparator 52 shown in the figure, for example. The voltage sensed by the voltage sensing circuit 46 and the zero voltage reference 54 can be used as an input to the zero voltage comparator 52. Then, an output signal 56 representing the zero crossing of the power supply voltage of the load circuit 34 is generated. Similarly, the zero crossing of the load current I _LOAD 42 can be detected using a comparator such as the illustrated zero current comparator 60. The current sensed by the current sensing circuit 48 and the zero current reference 58 can be used as the input of the zero current comparator 60. An output signal 62 representing the zero crossing of the load current I _LOAD 42 can then be generated.

The control circuit 16 can use the output signals 56 and 62 to determine when to change (eg, open or close) the current operating state of the MEMS switch 20 (or array of MEMS switches). More specifically, the control circuit 16 facilitates arc-less opening of the MEMS switch 20 to shut off or open the load circuit 34 in response to the detected zero crossing of the AC load current I _LOAD 42. Can be configured. Further, the control circuit 16 can be configured to facilitate arcless closing of the MEMS switch 20 to complete the load circuit 34 in response to a detected zero crossing of the AC power supply voltage. .

  In one embodiment, the control circuit 16 can determine whether to switch the current operating state of the MEMS switch 20 to the next operating state based at least in part on the state of the enable signal 64. The enable signal 64 can be generated, for example, as a result of a power off command in a contactor application. In one embodiment, enable signal 64 and output signals 56 and 62 can be used as input signals to dual D flip-flop 66 as shown. As will be described in more detail with respect to FIGS. 7-8, these signals close the MEMS switch 20 at the first power supply voltage zero after the enable signal 64 is activated (eg, triggered on a rising edge) to enable the enable signal. It can be used to open the MEMS switch 20 with zero initial load current after 64 has been deactivated (eg, triggered on a falling edge). With respect to the schematic 18 shown in FIG. 2, the enable signal 64 is active (high or low depending on the specific implementation) and either the output signal 56 or 62 is detected as zero voltage or zero current. Trigger signal 72 is generated whenever. In one embodiment, the trigger signal 72 can be generated using, for example, a NOR gate 70. The trigger signal 72 passes through the MEMS gate driver 74 to generate a gate activation signal 76 that applies a control voltage to the gate 26 (or each gate in the case of a MEMS array) of the MEMS switch 20. Can be used.

  As mentioned earlier, to obtain the desired rated current for a particular application, operate multiple MEMS switches in parallel (eg to form a switch module) instead of a single MEMS switch. Can be combined as possible. The combined capability of the MEMS switch can be designed to sufficiently withstand the continuous or transient overload current levels that the load circuit can experience. For example, in a 10 ampere RMS motor contactor with 6 times transient overload, there must be a sufficient number of parallel coupled switches to withstand 60 amperes RMS for 10 seconds. If the MEMS switch is switched within 5 microseconds when the current reaches zero using point-on-wave switching, 160 milliamperes will flow instantaneously when the contact is opened. Thus, for this application, each MEMS switch is capable of 160 milliamp “warm switching” and a sufficient number of MEMS switches must be placed in parallel to withstand 60 amps. On the other hand, a single MEMS switch must be able to interrupt the magnitude of current flowing at the moment of switching.

FIG. 3 shows a schematic diagram of one embodiment of a MEMS-based switch module 92. As shown, the switch module 92 can include a plurality of MEMS switches operably coupled in parallel between leads 98 and 100. In one embodiment, the plurality of MEMS switches in the switch module 92 can include one or more load contacts 94. According to one embodiment, the control circuit 16 (see FIG. 1) can generate one or more signals for initiating opening or closing of the plurality of load contacts 94 substantially simultaneously. Due to slight design variations between the load contacts 94, it is possible that not all load contacts will open or close simultaneously. Thus, there may be one load contact that switches last and withstands the entire current of the switch module 92 for a short time (eg, on the order of a few microseconds). Thus, load contact 94 is relatively small, yet it is also relatively small (eg, on the order of about 50 mA to about 1 ampere), and steady state load current I _LOAD 42 (FIG. 2) of load circuit 34 (see FIG. 2). Reference) can be designed.

  However, the switch that opens last in the switch module 92 may be required to cut off 10 mA to 100 mA, depending on the design of the switch array and switching control. In one embodiment, it may be desirable to use switching contacts 102 in addition to one or more load contacts 94 to facilitate the final interruption of load current in switch module 92. The switching contact 102 can be designed to handle a larger current than the load contact 94. Increasing the current carrying capability of the switching contact 102 may require the switching contact to be larger than the load contact 94, but a smaller number of switching contacts 102 can be used.

  Also, in some embodiments, a non-linear resistor 104, such as a varistor, can be used to absorb residual inductive energy from the switch module 92. Nonlinear resistor 104 can include, for example, a metal oxide varistor (MOV). Such a non-linear resistor 104 can be included in the design of the switch module 92 to clip the peak of the recovery voltage and / or to absorb residual inductive energy from the load circuit. The MOV can be selected based on peak voltage, peak current, and energy absorption characteristics. In some embodiments, the peak voltage of the load circuit can be set to about 1.6 times the peak of the steady state rated voltage. A factor of 1.6 helps to control the amount of energy absorbed by the MOV. The rated current can be set to a peak current that is expected to flow when the contact opens.

The switch module 92 can further include a snubber circuit coupled across the nonlinear resistor 104. The snubber circuit may include a snubber capacitor C _SNUB 106 and a snubber resistor R _SNUB 108 coupled in series therewith. The snubber capacitor C _SNUB 106 can facilitate improved transient voltage distribution during the sequence of opening of the MEMS switch. Furthermore, the snubber resistor 108 can suppress the current pulse generated by the snubber capacitor C _SNUB 106 during the closing operation of the switch module 92. In addition, the switch module 92 can include a leak contact 110 coupled in series with the non-linear resistor 104. Note that the leak contact 110 can include a MEMS switch. This leakage contact 110 removes the effects of capacitive and non-linear resistive elements (eg, non-linear resistor 104, C _SNUB 106, R _SNUB 108, etc.) from the switch module 92, thereby allowing steady state leakage through the switch module 92. It can be configured to reduce the current. The switch module 92 can also include one or more leakage resistors 112, 114 that can be configured to provide a conductive path for leakage current in the switch module 92.

  In order to obtain a desired rated current, a plurality of MEMS switches or a plurality of MEMS switches or a plurality of MEMS switches can be operably coupled in parallel to form a switch module, as well as to obtain a desired rated voltage. The switch modules can be operably coupled in series. FIG. 4 shows a schematic diagram of an exemplary MEMS-based switch array 116 according to one embodiment. As shown in FIG. 4, the switch array 116 can include a plurality of switch modules 118 operably coupled in series. Note that each of the plurality of switch modules 118 can include at least one MEMS switch. In one embodiment, the one or more switch modules 118 represent the switch module 92 of FIG. In the configuration contemplated herein, the switch array 116 is shown as including two or more switch modules 118 operably coupled in series between leads 122 and 124. The number “M” of modules coupled in series can be determined by the peak rated voltage of the soft switching system 10 (see FIG. 1).

Further, each of the plurality of switch modules 118 may include a respective grade relaxation resistor R _GRADE 126 coupled across each of the plurality of switch modules 118. The slope relaxation resistor R _GRADE 126 can provide a conduction path for steady state voltage slope relaxation despite very little leakage current to ground. More specifically, in the switch array 116, leakage current from the MEMS switches to ground can result in a very uneven voltage distribution when all MEMS switches are open. Steady-state voltage distribution can be achieved using gradient relaxation resistors R _GRADE 126, which allow a fraction of a microampere to flow through switch array 116 to leak current to ground. Nevertheless, the voltage distribution can be made uniform. The grade relaxation resistor R _GRADE 126 can be selected based on the expected leakage current through the MEMS switch from line to ground. In addition, the switch array 116 can also include capacitors 130, 132 configured to facilitate control of the rate of rise of the recovery voltage.

Referring now to FIG. 5, a system model schematic diagram 134 of an exemplary MEMS-based switching system is shown. The illustrated MEMS-based switching system 134 includes a switch array 136, such as the switch array 116 of FIG. As shown, the MEMS-based switching system 134 includes an alternating current (AC) voltage source V _SOURCE 138, a power supply inductance L _SOURCE 140, and a power supply resistor R _SOURCE 142. AC voltage source 138, power source inductance L _SOURCE 140, and power source resistance R _SOURCE 142 shall represent a Thevenin equivalent circuit of the power source that may arise from the secondary side of the transformer, for example, in powering switch array 136 Can do. Further, the power supply inductance L _SOURCE 140 may represent the combined inductance of the bus and cable as viewed from the switch array 136.

Further, the illustrated MEMS-based switching system 134 includes a passive load, which may include a load inductance L _LOAD 146 and a load resistor R _LOAD 148 coupled in series therewith. The MEMS based switching system 134 may also include a power capacitor C _SOURCE 144 and a load capacitor C _LOAD 150. The power supply (C _SOURCE 144) and load (C _LOAD 150) capacitors can control the rate of increase of the recovery voltage across the switch array 136. Without such a power supply and load capacitor, an arc can occur in the switch array 136 when the inductive load current is interrupted. To suppress capacitive leakage current through the switch array 136 when open or non-conductive, the power supply capacitor C _SOURCE 144 and the load capacitor C _LOAD 150 are not coupled directly across the switch array 136, but instead are coupled to the line. Note that can be coupled to ground. Further, the power supply (C _SOURCE 144) and load (C _LOAD 150) capacitors can facilitate the reduction of voltage stress on the switch array 136 when the load is interrupted.

  Referring now to FIG. 6, a flowchart 196 of one embodiment of a method for switching an exemplary MEMS-based soft switching system from the current operating state to the next state is shown. As described above, the detection circuit and the control circuit are operably coupled to the switching circuit, the detection circuit can be configured to detect a zero crossing of the AC power supply voltage or AC load current, and the control circuit is detected Responsive to zero crossing, the MEMS switch can be configured to facilitate arcless switching.

  As shown in FIG. 6, the current level and / or power supply voltage level in the load circuit is monitored as indicated by block 198. In one embodiment, the current level and / or power supply voltage level can be monitored using, for example, the detection circuit 14 (see FIG. 1). Further, as indicated by block 200, a zero crossing of the power supply voltage and load current is detected, for example, by a detection circuit. As shown in block 202, a trigger signal may be generated in response to the detected zero crossing. As shown in block 204, the trigger signal is configured to facilitate switching of the current operating state of the MEMS switch.

  Blocks 198-204 can be better understood with reference to FIGS. FIG. 7 shows a graph 206 of exemplary simulation results representing a MEMS switch that closes near zero voltage in a MEMS-based soft switching system according to an aspect of the present invention. As shown in FIG. 7, the change in amplitude 208 versus the change in time 210 is plotted.

  The response curve 212 represents the change in amplitude of the enable signal voltage as a function of time. Reference numeral 214 represents a region on the response curve 212 where the enable signal voltage has reached a steady logic high state. The change in power supply voltage amplitude as a function of time is represented by response curve 216. Similarly, the change in load current amplitude as a function of time is represented by response curve 218. The response curve 220 represents the change in gate voltage amplitude as a function of time. Also, the region where the gate voltage transitions to the logic high state on the response curve 220 is indicated by reference numeral 222. Further, reference numeral 224 represents a zero crossing of the power supply voltage.

  As described above with reference to FIG. 2, the power supply voltage and the load current are continuously detected using the detection circuit. The detection circuit is further used to detect a zero crossing of the power supply voltage and load current. This detected zero crossing information is then used to set the state of the enable signal. In the embodiment shown in FIG. 7, the enable signal voltage 212 is set to a logic high state in response to a detected zero crossing of the power supply voltage. Further, enable signal 212 is shown as achieving a steady high state at reference point 214.

  In accordance with exemplary aspects of the invention, the MEMS switch can be closed at the first zero crossing of the supply voltage after the enable signal voltage has achieved a steady logic high state. The first zero crossing of power supply voltage 216 after enable signal 212 achieves a steady logic high state is represented by reference numeral 224. When associated with the initial power supply voltage zero cross 224, the gate voltage 220 can be pulled high to facilitate switching the MEMS switch to the closed state. As a result, load current begins to flow through the MEMS switch, as shown by response curve 218. Thus, in response to the detected zero crossing of the AC supply voltage, the MEMS switch is closed in an arc-free manner to complete the load circuit. In other words, the MEMS switch is closed when the power supply voltage is near zero, thereby suppressing arcs that may be formed between the contacts of the MEMS switch.

  FIG. 8 shows a graph 226 of exemplary simulation results representing a MEMS switch opening near zero current in a MEMS-based soft switching system according to an aspect of the present invention. As shown in FIG. 8, the change in amplitude 228 versus the change in time 230 is plotted.

  Response curve 232 represents the change in amplitude of the enable signal voltage as a function of time. Reference numeral 234 represents a region on the response curve 232 where the enable signal has reached a steady logic low state. The change in power supply voltage amplitude as a function of time is represented by response curve 236. Similarly, the change in load current amplitude as a function of time is represented by response curve 238. The response curve 240 represents the change in gate voltage amplitude as a function of time. Further, reference numeral 242 represents a region on the response curve 240 where the gate voltage transitions to a logic low state.

  As can be seen from FIG. 8, the voltage of enable signal 232 that is currently in a logic high state is set to a logic low state in response to a detected zero crossing of the load current. Further, the voltage of enable signal 232 is shown to achieve a logic low state at reference point 234.

  The MEMS switch can be opened at the first zero crossing of the load current after the enable signal achieves a steady logic low state. Also, the first zero crossing of the load current 238 after the enable signal 232 has achieved a steady low state is represented by reference numeral 234. When associated with the initial load current zero crossing 234, the gate voltage 240 can be pulled low to facilitate switching the MEMS switch to an open circuit. As a result, as shown in response curve 236, the power supply voltage that was previously non-conductive begins to appear across the MEMS switch. Thus, in response to the detected zero crossing of the AC load current, the MEMS switch is opened in an arc-free manner to interrupt the load circuit. In other words, the MEMS switch is opened near a load current of zero, thereby suppressing arcs that can form between the contacts of the MEMS switch.

  Although only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. Accordingly, all such modifications and changes are to be understood as being included within the scope of the present invention and as encompassed by the appended claims.

1 is a block diagram of an exemplary MEMS-based switching system in accordance with aspects of the present technique. FIG. 1 is a schematic diagram of an exemplary MEMS-based switching system in accordance with aspects of the present technique. FIG. 2 is a schematic diagram of an exemplary MEMS-based switch module according to aspects of the present technique. FIG. FIG. 3 is a schematic diagram of an exemplary MEMS-based switch array in accordance with aspects of the present technique. 1 is a schematic diagram illustrating a system model of an exemplary MEMS-based switching system, according to aspects of the present technique. FIG. 3 is a flow diagram illustrating operational phases of an exemplary MEMS-based switching system, in accordance with aspects of the present technique. 3 is a graph illustrating exemplary simulation results representing the closing of a MEMS switch in the MEMS-based switching system of FIG. 2 in accordance with aspects of the present technique. 3 is a graph illustrating exemplary simulation results representing the opening of a MEMS switch in the MEMS-based switching system of FIG. 2 in accordance with aspects of the present technique.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Soft switching system 12 Switching circuit 14 Detection circuit 16 Control circuit 18 Example MEMS-based switching system 20 MEMS switch 22 Drain 24 Source 26 Gate 28 Single package 29 Damping circuit 30 Snubber capacitor 32 Snubber resistor 34 Load circuit 36 AC Voltage source 38 Load inductance 40 Load resistance 42 Load current 44 Ground 46 Voltage detection circuit 48 Current detection circuit 52 Zero voltage comparator 54 Zero voltage reference 56 Zero voltage comparator output 58 Zero current comparator 60 Zero current reference 62 Zero current comparison Output 64 Enable signal 66 Dual D flip-flop 70 NOR gate 72 Trigger signal 74 MEMS gate driver 76 Gate activation signal 92 Switch module 4 Load contact 98, 100 Lead 102 Switching contact 104 Nonlinear resistor 106 Snubber capacitor 108 Snubber resistor 110 Leak contact 112, 114 Leak resistor 116 Switch array 118 First switch module 120 Second switch module 122 First lead 124 Second Lead 126 Gradation Relaxation Resistor 130, 132 Capacitor 134 Switching System 136 Switch Array 138 Voltage Source 140 Power Inductor 142 Power Resistor 144 Power Capacitor 146 Load Inductor 148 Load Resistor 150 Load Capacitor 196 Demonstrates Operation of Switching System Flow chart 198-204 Stages included in flow chart 196 206 Simulation results representing zero voltage turn-on of the switching element 208 Amplitude 210 Time 212 Enable signal 214 Region where enable signal voltage reaches steady logic high state 216 Power supply voltage 218 Load current 220 Gate voltage 222 Region where gate voltage transitions to logic high state 224 Zero cross of power supply voltage 226 Graph showing simulation results representing zero current turn-off of switching element 228 Amplitude 230 Time 232 Enable signal 234 Region where enable signal voltage reaches steady logic low state 236 Power supply voltage 238 Load current 240 Gate voltage 242 Gate voltage is logic low state Transition area to

Claims (10)

A detection circuit (14) configured to detect the occurrence of a zero crossing of the AC power supply voltage (36) or the AC load current (42);
A switching circuit (12) coupled to the detection circuit (14) and comprising a microelectromechanical system switch (20);
Coupled to the detection circuit (14) and the switching circuit (12), in response to a detected zero crossing of the AC power supply voltage (36) or the AC load current (42), the microelectromechanical system switch (20) A system (10) comprising: a control circuit (16) configured to perform arc-free switching. In response to the detected zero crossing of the alternating load current (42), the control circuit (16) turns the microelectromechanical system switch (20) arcless to interrupt the load circuit (34). The system (10) of claim 1, wherein the system (10) is configured to open to In response to the detected zero crossing of the AC power supply voltage (36), the control circuit (16) turns the microelectromechanical system switch (20) arcless to complete the load circuit (34). The system (10) of claim 1, wherein the system (10) is configured to be closed. The system (10) of claim 1, further comprising a snubbing circuit (106, 108) configured to delay the appearance of a voltage across the microelectromechanical system switch (20). The switching circuit (12) further comprises a switch module (92) coupled to the control circuit (16) and the detection circuit (14) and comprising a plurality of microelectromechanical system switches (20), the control circuit ( 16) is configured to perform arc-free switching of at least one of the plurality of microelectromechanical system switches (20) in response to a detected zero crossing of an AC power supply voltage (36) or an AC load current (42). The system (10) of claim 1, wherein: The system (10) of any preceding claim, wherein the switching circuit (12) further comprises a plurality of switch modules (92) coupled in a series circuit. At least one of the plurality of switch modules (92),
A load contact;
The system (10) of claim 6, comprising: a switching contact, wherein at least one of the load contact and the switching contact comprises a microelectromechanical system switch. The system (10) of claim 6, further comprising a graded resistor (126) coupled in parallel with the at least one switch module (118). Monitoring (198) an AC power supply voltage (36) or an AC load current (42) in the switch array (116, 136), comprising a plurality of switch modules (118) having the switch circuits coupled in series; Monitoring (198) an AC power supply voltage (36) or an AC load current (42) comprising:
Detecting the occurrence of zero crossing of the AC load current (42) or the AC power supply voltage (36) (200);
Generating a trigger signal (72) in response to the detected zero crossing (202), wherein the trigger signal (72) facilitates switching of the current operating state of the microelectromechanical system switch (20); Generating a trigger signal (72) configured to:
Switching (204) each current state of the plurality of switch modules (118) in response to the trigger signal (72) (196). Switching the current state comprises:
Triggering the load contact (94) and the at least one switching contact (102) such that the load contact (94) is triggered before the at least one switching contact (102);
To interrupt non-zero current in the switching circuit (12), the load contact (94) and the at least one of the load contacts (94) are opened before the at least one switching contact (102). Opening one switching contact (102) arclessly;
In order to complete the switching circuit (12) when a non-zero voltage appears across the switch, the load contact (94) and the at least one switching contact (102) are closed arclessly. The method (196) of claim 9, comprising the steps of:

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