Thyristor current interrupter and auxiliary quasi-resonant turn-off unit

Abstract

An apparatus and method capable of accelerating turn-off time of a thyristor current interrupter. After commutation of load current from a main thyristor to an auxiliary turn-off unit, a capacitor of the auxiliary turn-off unit can provide a resonant current to create a current zero crossing for turn-off of the main thyristor and provide a reverse bias voltage for the main thyristor. The auxiliary turn-off unit can maintain the main thyristor off and facilitate sufficient time for the main thyristor to block a forward system voltage. With the switch of the auxiliary turn-off unit and the main thyristor off, a voltage level of another capacitor of the auxiliary turn-off unit can be increased to a level to trigger at least one voltage clamping unit to absorb electrical power from the capacitor. As the electrical power is absorbed, the load current into the auxiliary turn-off unit can be reduced to a level at which one or more auxiliary thyristor switches of the auxiliary turn-off unit can be turned off.

Description

Technical Field

[0001] This invention relates to circuit interrupters, and more particularly to thyristor current interrupters having auxiliary capability to force the resonant turn-off condition of the main thyristor. Background Technology

[0002] Thyristors (SCRs), applicable to a variety of power applications, offer relatively high current capacity in a single package and suffer from relatively low conduction power losses. Furthermore, thyristors are generally readily available and have proven reliability. Additionally, they are often relatively inexpensive compared to at least some other types of power semiconductor switches. However, a traditional disadvantage of using thyristors in power applications is the uncontrollable turn-off capability, which can result in a time delay before the thyristor interrupts AC current or fails to interrupt DC current. Moreover, compared to other semiconductor switches, thyristors typically must wait for the current to cross zero or drop below the holding current before they can be turned off, for example, from a closed state to an open state.

[0003] This time delay before the thyristor can be turned off can create dangerous situations and potentially damage related equipment and electrical components. For example, thyristors can be used as the main power switch in microgrid circuit breakers that connect the public grid to microgrids with distributed generation, including solar farms, wind turbines, energy storage systems, and / or diesel generators. If a power outage occurs while distributed generation continues to power the microgrid, a microgrid circuit breaker may be needed to quickly isolate the microgrid from the public grid. However, with microgrid circuit breakers using conventional thyristors, the delay can be relatively long, waiting for the current to cross zero or drop below the holding current before the circuit breaker can be turned off. During this delay, however, the fault current or energy may grow to a relatively dangerous level, at least in some instances, that could disable and shut down the entire power network.

[0004] Thyristors can also be used as static transfer switches (STS) in conjunction with switching or conversion between power supply sources. Typically, in response to the detection of power quality events, the STS can utilize a "break-before-make" method for power source transfer. According to this method, upon detection of a power quality event (such as, for example, a power outage, a fault, or other problems related to the quality and / or supply of electrical power), a first active thyristor switch can be used to isolate the primary power source. For example, the first active thyristor switch can become inactive by switching from a closed state to an open state. However, this isolation can be delayed while the first active thyristor switch waits for the current to cross zero or for the current to drop below the associated holding current. After the first active thyristor switch is opened, a second passive thyristor switch coupled to the secondary power source can be closed to become active. In at least some instances, activation of the second thyristor can be delayed, for example, due to downstream transformer flux matching and inrush current limitations. Therefore, the disconnection time associated with turning off the first thyristor switch can be a significant portion of the total switching time associated with switching from the primary power source to the auxiliary power source. For example, the switching gap between turning off the first active thyristor switch and turning on the second passive thyristor switch can sometimes be a full electrical cycle. Such a relatively long gap can challenge and disrupt mission-critical loads, including, for example, downstream computer-based servers and databases. Furthermore, certain components of the load may also need to be configured to ensure the continuous operation of equipment or components during such relatively long switching times, for example, by using additional capacitors and / or extra-large capacitors, which can be costly.

[0005] Therefore, although various current interruptors are currently available on the market, there may be other improvements when operating thyristor current interruptors. Summary of the Invention

[0006] One aspect of this application is an apparatus that may include a main thyristor having at least one main thyristor switch and an auxiliary turn-off unit that may be connected in parallel with the main thyristor. The auxiliary turn-off unit may include one or more pairs of auxiliary switches, multiple capacitors, a semiconductor switch, and at least one voltage clamping unit. Additionally, each of the one or more pairs of auxiliary switches may include an auxiliary thyristor switch. The auxiliary turn-off unit may be configured to commutate load current from the main thyristor to the semiconductor switch of the first pair of auxiliary switches and the auxiliary turn-off unit when the semiconductor switch transitions from an off state to an on state. Further, at least one of the multiple capacitors may be configured and positioned to provide a resonant current or quasi-resonant current to generate a current zero-crossing point for the main thyristor after the commutation of load current to the auxiliary turn-off unit, thereby changing the main thyristor from a thyristor-on state to a thyristor-off state. This quasi-resonant current may relate to a resonance that occurs within a small fraction of a typical resonant time period due to a change in circuit state. Additionally, at least one of the capacitors may be configured to increase the voltage level when the switch is switched to the off state and the main thyristor is in the thyristor off state. At least one voltage clamping unit may be configured to draw energy from at least the other capacitor, at least until the load current through the first pair of auxiliary switches decreases to a level sufficient to at least switch the auxiliary thyristor to the off state.

[0007] Another aspect of the embodiments of this application is a thyristor current interrupter, which may include a main thyristor having one or more main thyristor switches and an auxiliary turn-off unit that may be connected in parallel with the main thyristor. The auxiliary turn-off unit may have at least a first switch, at least one auxiliary thyristor, a first capacitor, and a second capacitor. Further, the auxiliary turn-off unit may be configured to at least (1) commutate the load current from the main thyristor to the auxiliary turn-off unit when the first switch is switched to the on state, (2) provide a resonant current or quasi-resonant current to generate a current zero crossing point for the main thyristor, (3) increase the voltage level of the first capacitor when both the first switch and the main thyristor are switched to the off state, and (4) reduce the load current in the auxiliary turn-off unit to a level suitable for switching at least one auxiliary thyristor to the off state when the voltage level of the first capacitor reaches a threshold level.

[0008] Additionally, one aspect of an embodiment of this application is a method that may include: activating a switch of an auxiliary turn-off unit of a thyristor current interruptor and a plurality of auxiliary switches, the plurality of auxiliary switches including at least one auxiliary thyristor switch; commutating load current from the main thyristor of the thyristor current interruptor to the auxiliary turn-off unit, the main thyristor including at least one main thyristor switch. Further, the resonant current may be transmitted through at least a portion of the auxiliary turn-off unit in a manner that at least reduces the load current through the main thyristor. Additionally, the switch of the auxiliary turn-off unit may be deactivated, and after the switch is deactivated, the voltage level of a first capacitor of the auxiliary turn-off unit may be increased. The method may further include: one or more voltage clamping units absorbing electrical power from the first capacitor. Further, since the one or more voltage clamping units absorb electrical power, the load current in the auxiliary turn-off unit may be reduced. Further, when the load current in the auxiliary turn-off unit decreases below the holding current or at a current zero-crossing point, at least one auxiliary thyristor switch of the auxiliary turn-off unit may be deactivated.

[0009] These and other aspects of the invention will be better understood in view of the accompanying drawings and the following detailed description. Attached Figure Description

[0010] The description herein refers to the accompanying drawings, in which the same reference numerals refer to the same parts in several views.

[0011] Figure 1 A block diagram of an exemplary thyristor current interruptor switch according to an illustrated embodiment of this application is shown.

[0012] Figure 2 The illustration shows an exemplary auxiliary turn-off unit and a main thyristor of a thyristor current interruptor switch according to an illustrated embodiment of the present application.

[0013] Figure 3 The illustrations show graphical representations of various aspects of an exemplary operation of a thyristor current interruptor switch according to an illustrated embodiment of the present application.

[0014] Figures 4a to 4f The illustration shows a thyristor current interruptor switch according to an illustrated embodiment of this application. Figure 3 Various control and operational states during the exemplary operation process depicted herein.

[0015] Figure 5 The illustration shows a graphical representation of the result of an exemplary current interruption of a thyristor current interruptor switch according to an illustrated embodiment of this application.

[0016] Figure 6 A block diagram of a static transfer switch (“STS”) having a plurality of thyristor current interruptor switches is shown according to an illustrated embodiment of the present application.

[0017] Figure 7 A block diagram of an exemplary thyristor current interruptor switch used in conjunction with a microgrid circuit breaker according to an illustrated embodiment of the subject matter application is shown.

[0018] Figures 8 to 10 The diagram illustrates an exemplary variation of the configuration of the auxiliary turn-off unit for the thyristor current interruptor switch used in this application.

[0019] The foregoing summary of the invention and the following detailed description of certain embodiments of the present application will be better understood when read in conjunction with the accompanying drawings. Certain embodiments are illustrated in the drawings for illustrative purposes. However, it should be understood that the present application is not limited to the arrangements and means shown in the drawings. Furthermore, the same numbers in the corresponding figures represent the same or equivalent parts. Detailed Implementation

[0020] For convenience, certain terms have been used in the foregoing description, but are not intended to be limiting. Words such as “upper,” “lower,” “top,” “bottom,” “first,” and “second” indicate direction in the referenced figures. This terminology includes the words specifically mentioned above, their derivatives, and words with similar meanings. Additionally, unless otherwise specified, the words “a” and “an” are defined as including one or more of the referenced items. The phrase “at least one,” followed by a list of two or more items (such as “A, B, or C”), means any one of A, B, or C, and any combination thereof.

[0021] Figure 1 A block diagram of an exemplary thyristor current interruptor switch 100 according to an illustrated embodiment of this application is shown. According to at least some embodiments, the thyristor current interruptor switch 100 can be used as a disconnect switch. Furthermore, the thyristor current interruptor switch 100 can be configured to interrupt the current supply through the thyristor current interruptor switch 100, thereby, for example, interrupting the current supply to a downstream load. As illustrated, the thyristor current interruptor 100 includes one or more main thyristors 102 connected in parallel to an auxiliary quasi-resonant turn-off unit 104.

[0022] As discussed in more detail below, the auxiliary turn-off unit 104 can accelerate the time it takes for the thyristor current interruptor 100 to interrupt the current flowing through and / or to the load side of the thyristor current interruptor 100. Furthermore, the auxiliary turn-off unit 104 can be activated when the thyristor current interruptor 100 is operated to interrupt the current. This activation of the auxiliary turn-off unit 104 facilitates the commutation of current from one or more main thyristors 102 to the auxiliary turn-off unit 104, thereby increasing the current in the auxiliary turn-off unit 104 while decreasing the current in one or more main thyristors 102. By commutating current from one or more main thyristors 102 to the auxiliary turn-off unit 104, the current level in one or more main thyristors 102 can relatively quickly drop to zero or below the level of the associated holding current within a relatively short time period (e.g., within approximately 10 microseconds (μs) to approximately 20 microseconds). Additionally, while facilitating the reduction of current in the main thyristor 102, the auxiliary turn-off unit 104 can apply a relatively small reverse bias voltage to the main thyristor 102, such as, for example, around 30 volts (V) to around 50 volts. Although the duration for which the auxiliary turn-off unit 104 applies the reverse bias voltage may vary, according to some embodiments, the auxiliary turn-off unit 104 can apply the reverse bias voltage to the main thyristor 102 for approximately 150 microseconds (μs) to approximately 200 microseconds. After applying the reverse bias voltage to the main thyristor 102, the main thyristor 102 can be in a deactivated or turned-off condition so that at least forward voltage transmission through the main thyristor 102 is no longer permitted. The turn-off unit 104 can then be turned off, thereby also turning off the auxiliary turn-off unit 104, thus completing the disconnection of the thyristor current interruptor 100.

[0023] like Figure 1As shown, power can be received at the line side 106 of the thyristor current interruptor 100 and output to the load side 108 of the thyristor current interruptor 100. According to some embodiments, the current and / or voltage through the thyristor current interruptor 100 can be monitored at the load side 108 of the thyristor current interruptor 100 (including, for example, via one or more sensors 110). For example, according to some embodiments, the sensor 110 on the load side 110 of the thyristor current interruptor 100 can be a current sensor that monitors the current flowing out of the thyristor current interruptor 100. Optionally or alternatively, the sensor 110 can be a voltage sensor that monitors the voltage flowing out of the thyristor current interruptor 100. Additionally, one or more sensors 110 can be part of the thyristor current interruptor 100 and / or electrically coupled to the load side 108 of the thyristor current interruptor 100. Additionally, according to some embodiments, the current and / or voltage delivered to the thyristor current interruptor 100 can be monitored at the line side 106 of the thyristor current interruptor 100 (e.g., via one or more sensors).

[0024] like Figure 1 As shown, the thyristor current interruptor 100 can be communicatively coupled to a controller 112, which receives information from one or more sensors of the thyristor current interruptor 100, including, for example, at least a sensor 110 on the load side 110 of the thyristor current interruptor 100. The controller 112 can be configured to utilize information provided to the controller 112 from the one or more sensors 110, as well as other information, when determining when to activate and deactivate each of the main thyristor 102 and the auxiliary shutdown unit 104. According to some embodiments, the controller 112 may include a processing device, such as, for example, a programmable, dedicated, and / or hardwired state machine, or any combination thereof. The processing device may include multiple processors, such as, for example, an arithmetic logic unit (ALU), a central processing unit (CPU), a digital signal processor (DSP), etc. A processing device having multiple processing units may also utilize distributed, pipelined, and / or parallel processing. The processing device may also be dedicated solely to performing the operations described herein or may be used for one or more additional applications.

[0025] In the depicted form, the processing device is programmable, executing algorithms and processing data according to operating logic defined by programming instructions (such as software or firmware) stored in memory that is part of or communicatively coupled to controller 112. Alternatively or additionally, the operating logic may be defined at least in part by hard-wired logic or other hardware. The processing device may include one or more components of any type adapted to process signals received from, for example, one or more sensors 110 and other devices, and to provide desired output signals, such as, for example, signals, to one or more main thyristors 102 and auxiliary shutdown units 104. These components may also include digital circuit systems, analog circuit systems, or a combination of both.

[0026] The memory can be of one or more types, such as solid-state, electromagnetic, optical, or combinations thereof. Additionally, the memory can be volatile, non-volatile, or combinations thereof, and some or all of the memory can be portable, such as disks, magnetic tapes, memory sticks, cassette tapes, etc. Furthermore, according to some embodiments, the memory can store data processed by the operating logic of the processing device, such as data representing signals received from and / or transmitted to sensor 110, replacing or superseding the stored programming instructions defining the operating logic.

[0027] Various types, configurations, and / or arrangements of thyristors can be used to provide one or more main thyristors 102. For example, see reference... Figure 2 According to some embodiments, the main thyristor 102 may be a bidirectional phase-controlled thyristor, which includes two thyristor switches arranged in anti-parallel configuration, namely, the first main thyristor switch 114a (S m1 ) and the second main thyristor switch 114b (S m2 According to these embodiments, the main thyristor 102 may include a switch 114a (S) for each main thyristor switch 114a. m1 ), 114b(S m2 The gate of the device, a gate configured to allow current to flow in the forward direction, and another gate configured to allow current to flow in the reverse direction.

[0028] Figure 2 An exemplary embodiment of an auxiliary shutdown unit 104 used with an alternating current (AC) power source 130 is also illustrated. According to the illustrated embodiment, the auxiliary shutdown unit 104 includes a plurality of auxiliary thyristor switches 116a to 116d (S r1 To S r4 Furthermore, the illustrated auxiliary shutdown unit 104 includes a first auxiliary thyristor switch pair (such as, for example, a first auxiliary thyristor switch 116a (S)). r1) and the fourth auxiliary thyristor switch 116d(S r4 )) and a second auxiliary thyristor switch pair (such as, for example, a second auxiliary thyristor switch 116b (S) r2 ) and the third auxiliary thyristor switch 116c (S r3 At least as Figure 2 As shown, according to at least one application where alternating current (AC) power is supplied to the thyristor current interruptor 100, the auxiliary turn-off unit 104 can have a bridge configuration such that during the positive half-cycle of the AC current, the first auxiliary thyristor switches 116a, 116d (S r1 S r4 Forward bias, and simultaneously during the negative half-cycle of the AC current, the second thyristor switches 116b and 116c (S) are... r2 S r3 Forward bias.

[0029] The auxiliary turn-off unit 104 may also include a semiconductor switch 118, more specifically, a fully controlled semiconductor switch with full current turn-off capability, including but not limited to insulated gate bipolar transfer (IGBT) switches, gate turn-off (GTO) thyristors, integrated gate commutated thyristors (IGCTs), bipolar junction transistors (BJTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), and junction field-effect transistors (JFETs) based on various semiconductor technologies such as silicon (Si), silicon carbide (SiC), gallium nitride (GaN), to name just a few. Therefore, although the semiconductor switch 118 of the illustrated embodiment is described and illustrated below in conjunction with IGBT(Sa) as the semiconductor switch 118, other types of semiconductor switches may also be used. Additionally, the auxiliary turn-off unit 104 may also include a first high-voltage resonant capacitor 120 (C r1 ), second low-voltage resonant capacitor 122 (C r2 The resonant inductor 124 (Lr) and voltage clamping unit 126 are also present. The resonant inductor 124 is positioned and configured to limit the rate of rise of the current. According to some embodiments, the resonant inductor 124 may be, for example, a section of cable or wire that connects the auxiliary turn-off unit 104 to the main thyristor 102 and uses the inductance of the wire or cable to limit the rate of rise of the current.

[0030] Configuring the auxiliary shutdown unit 104 allows it to function as an add-on module to the thyristor current interrupter 100 without altering the mechanical structure, cooling, and / or the electrical clamping connection of one or more main thyristors 102. Additionally, because the auxiliary shutdown unit 104 conducts current discontinuously, it does not generate additional power losses and can be used with relatively low-cost discrete thyristors and IGBT switches that have relatively good pulse capacity. Furthermore, the resonant inductance of the auxiliary shutdown unit 104 can be relatively small.

[0031] Although Figure 2 An embodiment of a thyristor current interruptor 100 used with an AC power source 130 is illustrated, but the thyristor current interruptor 100 can also be configured for use with a DC power source and other current sources. For example, Figure 2 The thyristor current interruptor 100 depicted can also be used in bidirectional current applications, including bidirectional current applications utilizing a DC power source. Additionally, although... Figure 2 The illustration shows a thyristor current interruptor 100 for single-phase current, but the thyristor current interruptor 100 can be used for each phase in a multiphase application. For example, for a three-phase application, each phase can utilize a separate thyristor current interruptor 100, wherein each thyristor current interruptor 100 has a main thyristor 102 and an auxiliary turn-off unit 104.

[0032] Additionally, such as Figure 2 As shown, according to some embodiments, the auxiliary IGBT switch 118, the first high-voltage resonant capacitor 120, and the voltage clamping unit 126 are connected in parallel with each other. Furthermore, various different types of devices or components can be used as the voltage clamping unit 126, such as, for example, one or more metal oxide varistors (MOVs), including but not limited to multiple MOVs arranged in parallel with each other.

[0033] The second low-voltage resonant capacitor 122 can be pre-charged to a relatively low voltage and can provide a resonant current to generate a current zero-crossing point for the main thyristor 102. The second low-voltage resonant capacitor 122 can also be configured to provide a reverse bias voltage via the auxiliary IGBT switch 118 to delay the main thyristor 102 after the load current has been transferred to the auxiliary turn-off unit 104, and to provide the main thyristor 102 with time to complete the internal carrier recombination process before the main thyristor 102 can block the forward system voltage. The auxiliary IGBT switch 118 can then be turned off, and the load current can be switched from the auxiliary IGBT switch 118 to the first high-voltage resonant capacitor 120. A second resonance can then be initiated, and the first high-voltage resonant capacitor 120 can limit the voltage change rate of the main thyristor 102 to prevent the main thyristor 102 from being triggered again in response to a higher voltage change rate. When the voltage of the first high-voltage resonant capacitor 120 reaches a sufficient level (including, for example, a level that the voltage of the first high-voltage resonant capacitor 120 may be limited by the parallel voltage clamping unit 126), the load current can be reduced to zero or interrupted. Then, the auxiliary thyristor switches 116a to 116d can be reverse-biased and turned off, for example, via the operation of the controller 112, and the current interruption via the thyristor current interruptor 100 can be completed. According to some embodiments, the total time for the thyristor current interruptor 100 to interrupt the current may be less than 350 microseconds (μs).

[0034] Figures 3 to 4f An exemplary operation of an embodiment of the thyristor current interruptor 100 is illustrated. Figures 4a to 4f The solid lines in the circuit diagram illustrate the current flow in the main thyristor 102 and the auxiliary turn-off unit 104, while the dashed lines represent paths through which current is not flowing. Figure 3 and Figure 4a As shown, the initial time period T0 (which can correspond to the normal operating conditions during the period when the thyristor current interruptor 100 is in the closed state) Figure 3 During this period, the first main thyristor switch 114a and the second main thyristor switch 114b of the main thyristor 102 (S m1 S m2 One of the main thyristor switches in the circuit conducts the load current to the load resistor 128 (R). load First main thyristor switch 114a and second main thyristor switch 114b (S) m1 S m2 Which main thyristor switch in the circuit is conducting load current can be determined based on various criteria, including, for example, the direction of the load current. Furthermore, as... Figure 4aAs shown in the illustrated example, during the initial time period T0, the first main thyristor switch 114a of the main thyristor 102 conducts the load current, while the auxiliary turn-off unit 104 is in the off condition. Therefore, as Figure 3 As shown, during the initial time period T0, no current is flowing through the auxiliary thyristor switches 116a to 116d of the auxiliary turn-off unit 104 (S). r1 S r2 S r3 S r4 ).

[0035] The initial time period T0 can continue during normal operating conditions, and until a power quality event occurs that triggers the operation of the thyristor current interruptor 100 in a manner that seeks to achieve a current interruption, such as, for example, a short circuit or an adverse change in the quality of the supplied or provided power. However, once a power quality event occurs, such as, for example, a power quality event detected by the controller 112 through information from the sensor 110, then at time T1( Figure 3 The turn-off process of the thyristor current interruptor 100 can then begin. Therefore, at time T1, at least some of the auxiliary thyristor switches 116a to 116d of the auxiliary turn-off unit 104 can be turned on (e.g., via operation of the controller 112). r1 S r2 S r3 S r4 ) and auxiliary IGBT switch 118. Auxiliary thyristor switches 116a to 116d (S r1 S r2 S r3 S r4 Which auxiliary thyristor switch in the thyristor 102 turns on at time T1 may depend on a variety of factors, such as, for example, the direction of the load current detected by, for example, current sensor 110, and / or the first main thyristor switch 114a and the second main thyristor switch 114b of the main thyristor 102. m1 S m1 Which main thyristor switch in the circuit is conducting the load current?

[0036] exist Figure 4b In the illustrated example, at time T1, in addition to auxiliary IGBT switch 118, the first auxiliary thyristor switch 116a and the fourth auxiliary thyristor switch 116d are turned on (e.g., via operation of controller 112). r1 S r4 At the same time, current is flowing through the first main thyristor switch 114a (S) of the main thyristor 102. m1 When the first auxiliary thyristor switch 116a (S) is turned on. r1 ), fourth auxiliary thyristor switch 116d(S)r4 ) and auxiliary IGBT switch 118, current can flow from the first main thyristor switch 114a (S) of the main thyristor 102. m1 ) Switching to the first auxiliary thyristor switch 116a (S) r1 ), auxiliary IGBT switch 118 and fourth auxiliary thyristor switch 116d (S) r4 ),like Figure 4b As shown. Therefore, as Figure 3 As shown, at time T1, when the current is flowing from the first main thyristor switch 114a (S) of the main thyristor 102... m1 During commutation, the first main thyristor switch 114a (S) of the main thyristor 102... m1 The current level in the auxiliary turn-off unit 104 (more specifically, the first auxiliary thyristor switch 116a and the fourth auxiliary thyristor switch 116d) is decreasing, while the current level in the auxiliary turn-off unit 104 (more specifically, the first auxiliary thyristor switch 116a and the fourth auxiliary thyristor switch 116d) is decreasing. r1 S r4 The current level in )) increases.

[0037] Furthermore, during time period T1, resonance can occur at the second low-voltage resonant capacitor 122 (C). r2 ) and resonant inductor 124 (L r It begins between ) and. The second low-voltage resonant capacitor 122 can be pre-charged to have Figure 4b The initial voltage (V) of the polarity shown co When the main thyristor 102 is turned on, the resonant current can flow through the first auxiliary thyristor switch 116a (S). r1 ), second low-voltage resonant capacitor 122 (C r2 ), auxiliary IGBT switch 118, fourth auxiliary thyristor switch 116d (S) r4 The resonant inductor 124. As previously mentioned, according to this embodiment, the resonant inductor 124 can limit the current rise rate (di / dt) of the resonant current to ensure soft commutation. Additionally, since the load current remains constant during time period T1, the increase in the resonant current will reduce the current through the main thyristor 102, thus affecting the first main thyristor switch 114a (S) of the main thyristor 102. m1 The current generates a zero-crossing point in the process.

[0038] During time period T1, the reverse recovery current can also be associated with the main thyristor 102. For example, the first main thyristor switch 114a and the second main thyristor switch 114b of the main thyristor 102 (S m1 S m2 Each main thyristor switch in the circuit can have three pn junctions. The first main thyristor switch 114a (S) m1In the active illustrated example, the first main thyristor switch 114a (S) m1 The charge carriers in two of the three pn junctions inside the thyristor can be swept out by the negative current spike. However, although the charge carriers in two of the three pn junctions may be swept out, the charge carrier charge may still be trapped in the other pn junction. Therefore, at the end of time period T1, although the first main thyristor switch 114a (S m1 The conduction current can be stopped, and the load current can be switched to the auxiliary turn-off unit 104, but the presence of charge carriers trapped in another pn junction can prevent the first main thyristor from switching 114a (S). m1 Prepare to block positive voltage.

[0039] Captured in the first main thyristor switch 114a(S) m1 The charge in the pn junction of the thyristor can be removed by recombination. However, an additional reverse bias time may be required to allow the first master thyristor switch 114a (S) to be fully turned off. m1 Therefore, the main thyristor 102 is allowed to be completely turned off. Thus, time period T2 can be used to allow the first main thyristor switch 114a (S) to switch. m1 There is time to complete carrier recombination. During time period T2, full-load current flows through the first auxiliary thyristor switch 116a (S). r1 ), second low-voltage resonant capacitor 122 (C r2 ), auxiliary IGBT switch 118, fourth auxiliary thyristor switch 116d (S) r4 ), and resonant inductor 124. Therefore, during time period T2, the load current has already flowed from the first main thyristor switch 114a (S) of the main thyristor 102. m1 The commutation ensures that no load current is flowing through the first main thyristor switch 114a (S) of the main thyristor 102. m1 In addition to other requirements, it may also be necessary to turn off the first main thyristor switch 114a (S). m1 ).

[0040] Additionally, during time period T2, the load resistor 128 (R load It can receive power source voltage and receive voltage from the second low-voltage resonant capacitor 122 (C). r2 The additional voltage applied by the second low-voltage resonant capacitor 122 (C) is compared to the voltage supplied by the power source 130. r2 The additional voltage provided may be relatively low. For example, according to some embodiments, it can be provided by another circuit to the second low-voltage resonant capacitor 122 (C). r2 Pre-charge voltage (V) coThe voltage can range from approximately 20 volts (V) to approximately 50 volts, while the power source voltage can be in the range of several hundred volts. As a result, the load resistor is 128 (R). load You will only see a small voltage increase or peak stress.

[0041] Meanwhile, in the first auxiliary thyristor switch 116a and the fourth auxiliary thyristor switch 116d (S R1 S R4 When activated, the second low-voltage resonant capacitor 122 (C) r2 A voltage (V) can be applied. co ),like Figure 4c As shown, the first main thyristor switch 114a (S) of the main thyristor 102 is reverse biased. m1 This allows the main thyristor 102 sufficient time to complete the reassembly. The second low-voltage resonant capacitor 122 (C...) r2 The voltage provided can be negative, when zero current is flowing through the first main thyristor switch 114a (S) of the main thyristor 102. m1 At the same time, this negative voltage is applied to the first main thyristor switch 114a (S) of the main thyristor 102. m1 ). In the first main thyristor switch 114a(S) m1 When the current is zero and a negative voltage is applied to the first main thyristor switch 114a (S) m1 In the case of ), the controller can turn off the first main thyristor switch 114a (S) within the time period T1. m1 Then, the main thyristor 102 is turned off during time period T2.

[0042] The duration of time period T2 can be controlled by the auxiliary IGBT switch 118 (S) a The operation of the second low-voltage resonant capacitor 122 (C) is controlled by the operation of the main thyristor 102. Additionally, the duration of time period T2 can be adjusted according to the reorganization requirements of different thyristors of the main thyristor 102. Therefore, for example, according to some embodiments, a duration margin of additional time can be added to the duration of time period T2 to extend the duration of time allocated to the main thyristor to complete reorganization. Thus, this method can provide a reliable and flexible way to turn off one or more main thyristors 102. Additionally, during time period T2, the second low-voltage resonant capacitor 122 (C) is... r2 The load current discharge and associated capacitance can be large enough to maintain voltage polarity and the first main thyristor switch 114a (S) of the main thyristor 102. m1 The reverse bias of ). Figure 4d As shown, at the end of time period T2, the first main thyristor switch 114a (S) of the main thyristor 102... m1 It can be prepared to block the positive voltage.

[0043] like Figure 3 and Figure 4d As shown, during time period T3, the current has been switched to the auxiliary IGBT switch 118 (S). a The first high-voltage resonant capacitor 120 (C) is connected in parallel. r1 And the second resonance can be initiated, thereby starting from the first auxiliary thyristor switch 116a and the fourth auxiliary thyristor switch 116d (S r1 S r4 The process of removing current. For example... Figure 4d As shown, during the second resonance period in time period T3, when ICBT 118 is off, the resonant current can flow through power source 130 and the first auxiliary thyristor switch 116a (S). r1 ), second low-voltage resonant capacitor 122 (C r2 ), First high-voltage resonant capacitor 120 (C r1 ), fourth auxiliary thyristor switch 116d(S) r4 ), resonant inductor 124 and load resistor 128 (R load First high-voltage resonant capacitor 120 (C) r1 The capacitance of the first high-voltage resonant capacitor 120 (C) may be relatively low, making the capacitance of the first high-voltage resonant capacitor 120 (C) relatively low. r1 The voltage of the first high-voltage resonant capacitor 120 (C) can be increased rapidly to interrupt the load current. r1 It can generate zero-voltage turn-off and minimize the turn-off power loss of the auxiliary IGBT switch 118.

[0044] First high-voltage resonant capacitor 120 (C) r1 It can also reduce the first main thyristor switch 114a (S) of the main thyristor 102. m1 The rate of increase of the forward blocking voltage (dv / dt). This is achieved through the first high-voltage resonant capacitor 120 (C). r1 Reducing the rate of increase of the forward blocking voltage (dv / dt) can prevent the voltage from rising to the level that could trigger the first main thyristor switch 114a (S) of the main thyristor 102, at least during the time period T3. m1 If the rate at which it is reconnected is allowed to trigger its reconnection, this could cause the thyristor current interruptor 100 to fail to interrupt the load current.

[0045] In at least some cases, if the load current is very high, then at the end of time period T3, the first high-voltage resonant capacitor 120 (C) r1 The voltage across the terminals may reach the threshold voltage set by the voltage clamping circuit. Therefore, during time period T4 ( Figure 3 During this period, such as Figure 4eAs shown, when the first high-voltage resonant capacitor 120 (C r1 When the voltage across the first high-voltage resonant capacitor 120 reaches a threshold voltage, such as, for example, the maximum voltage, the voltage clamping unit 126 can be activated. r1 The voltage established across the terminals will eventually be greater than the power source voltage, allowing the load current to be reduced to zero through the auxiliary shutdown unit 104. Additionally, the voltage clamped by the voltage clamping unit 126 can be greater than the voltage of the power source 130, which is supplied with power through the thyristor current interrupter 100.

[0046] When activated, the voltage clamping unit 126 can have a relatively low impedance to allow the load current in the auxiliary shutdown unit 104 to be conducted through the voltage clamping unit 126. Since the load current is conducted through the voltage clamping unit 126, the voltage clamping unit 126 can absorb relevant energy, thereby reducing the load current flowing through the auxiliary shutdown unit 104 until the load current passes through the auxiliary first auxiliary thyristor switch 116a and the fourth auxiliary thyristor switch 116d (S). r1 S r4 The load current reaches the zero-crossing point. After the load current reaches the zero-crossing point, the resonant current may be at the first auxiliary thyristor switch 116a (S). r1 ) and the fourth auxiliary thyristor switch 116d(S r4 The circuit was interrupted after a brief reverse recovery current.

[0047] refer to Figure 3 and Figure 4f During time period T5, the load current has been interrupted, and the first main thyristor switch 114a (S) of the main thyristor 102... m1 The first high-voltage resonant capacitor 120 (C) has already been subjected to the voltage of power source 130. r1 The voltage across the terminals is greater than the voltage of the power source 130 and the residual voltage of the second low-voltage resonant capacitor 122 (C). r2 The sum of ) is so that the first high-voltage resonant capacitor 120 (C r1 ) can be the first auxiliary thyristor switch 116a and the fourth auxiliary thyristor switch 116d (S r1 S r4 A reverse bias voltage is provided. Then, the first auxiliary thyristor switch 116a and the fourth auxiliary thyristor switch 116d (S) can be reconfigured. r1 S r4 The internal charge carrier charge of the first auxiliary thyristor switch 116a and the fourth auxiliary thyristor switch 116d is ensured to be completely turned off. r1 S r4 ). For example Figure 4f As shown, at time T6 ( Figure 3The full current interruption is completed, and the load resistor 128 and power source 130 are disconnected through the thyristor current interruptor 100. The total turn-off time from the time when the auxiliary turn-off unit is activated (time period T1) to the time when the load and power source 130 are disconnected through the thyristor current interruptor 100 in time period T6 can be, for example, about 350 microseconds.

[0048] exist Figures 3 to 4f The above example is discussed and explained using a single-phase AC power source 130. Furthermore, the above discussion and... Figures 3 to 4f The example shown in the figure depicts a first main thyristor switch 114a (S) in which current is flowing through the main thyristor 102. m1 This causes the activation of the first auxiliary thyristor 116a and the fourth auxiliary thyristor 116d of the auxiliary shutdown unit 104 (S r1 S r4 In the case of a power event occurring during the half-cycle of the main thyristor 102, however, in other cases, a power event may occur when the current changes to the second main thyristor switch 114b (S) that is currently flowing through the main thyristor 102. m2 This may therefore lead to the activation of the second auxiliary thyristor switch 116b and the third auxiliary thyristor switch 116c of the auxiliary shutdown unit 104 (S). r2 S r3 During the half-cycle period of the main thyristor 102. Therefore, although the above discussion involves a first main thyristor switch 114a (S) involving current flowing through the main thyristor 102. m1 The first auxiliary thyristor switch 116a and the fourth auxiliary thyristor switch 116d of the auxiliary shutdown unit 104 (S) r1 S r4 The relevant activation situation is as described above, but the discussion and explanation can be similarly applied to the second main thyristor switch 114b (S) where current is flowing through the main thyristor 102. m2 ) and the second auxiliary thyristor switch 116b and the third auxiliary thyristor switch 116c of the auxiliary shutdown unit 104 (S r2 S r3 The above examples can be applied to unidirectional and bidirectional current systems that can utilize other types of power, including but not limited to DC applications and multiphase current applications.

[0049] Additionally, depending on other applications, instead of having a first main thyristor switch 114a and a second main thyristor switch 114b (S m1 S m1 ), at least as Figure 2 As shown, the main thyristor 102 may include only a single main thyristor switch 114a (S m1According to this embodiment, the auxiliary shutdown unit 104 may include only a single pair of auxiliary thyristors, such as, for example, the first auxiliary thyristor 116a and the fourth auxiliary thyristor 116d illustrated. r1 S r4 (instead of having an auxiliary thyristor pair)

[0050] Figure 5 The illustration shows a graphical representation of the result of an exemplary current interruption of a thyristor current interruptor 100 according to an illustrated embodiment of this application. In this illustrated example, the voltage of the power source is 100V DC, and the load resistor is 128 (R). load The resistance of the second low-voltage resonant capacitor is 1 ohm, and the second low-voltage resonant capacitor is 122 (C). r2 The thyristor 102 is precharged to 40 volts, and the main thyristor 102 conducts a load current of 100 amperes. As previously described, (such as via, for example, turning on the first auxiliary thyristor switch 116a and the fourth auxiliary thyristor switch 116d (S) r1 S r4 ) and IGBT switch 118 (S a Activating the auxiliary shutdown unit 104 can initiate the current interruption process. Figure 5 In this context, the start of the current interruption process and the corresponding current commutation from the main thyristor current of the main thyristor 102 to the auxiliary turn-off unit 104 can be considered as the beginning of the first time period. Figure 5 The “T1” in the text extends to the second time period ( Figure 5 (T2 in the original text). Further, after the current commutation from the main thyristor 102 ends, the reverse recovery process of the main thyristor 102 can occur during the second time period (T2). As discussed above, after the reverse recovery of the main thyristor 102, a reverse bias voltage, such as, for example, a negative voltage of approximately 40 volts, can be applied to the main thyristor 102. Then, the main thyristor current can be stopped, and the internal reconfiguration process of the main thyristor 102 can begin, as in the third time period (T2). Figure 5 As shown in "T3" in the diagram. According to some embodiments, the reverse recovery and internal reconfiguration process may take approximately 130 microseconds. Further, the IGBT switch 118 may be turned on for a period of time during and before and / or after the reverse recovery and internal reconfiguration process of the main thyristor 102. For example, according to some embodiments, although the reverse recovery and internal reconfiguration process takes approximately 130 microseconds, the IGBT switch 118 may be turned on within approximately 150 microseconds. Moreover, the turn-on time of the IGBT switch 118 is adjustable to ensure that the main thyristor 102 completes the reverse recovery and internal reconfiguration process before the IGBT switch 118 is turned off, so as to at least ensure that the main thyristor 102 is ready to block the forward voltage.

[0051] like Figure 5As shown, after the IGBT switch 118 is turned off, the voltage rise rate (dv / dt) of the main thyristor 102 can be limited to 40V / μs, which is relatively much lower than the erroneous trigger value that could re-trigger the main thyristor 102 to turn on. Furthermore, after the IGBT switch 118 is turned off, the voltage of the main thyristor 102 can increase to be greater than the power source voltage, which can reduce the load current to zero.

[0052] In the first auxiliary thyristor switch 116a and the fourth auxiliary thyristor switch 116d (S) of the auxiliary shutdown unit 104 r1 S r4 After the turn-off and full-quasi-resonant turn-off operation is completed, the main thyristor 102 can successfully block or interrupt the 100V system voltage. According to some embodiments, the total current interruption time obtained by the thyristor current interruptor 100 in this case can be about 300 microseconds (μs).

[0053] According to various embodiments, the thyristor current interruptor 100 can also be used in conjunction with a changeover switch. In such embodiments, including an auxiliary shutdown unit 104 can reduce the switching time associated with switching different power sources. For example, Figure 6 A block diagram of a three-phase static transfer switch 132 (“STS”) having a plurality of thyristor current interruptors 100a, 100b (“q-RTO”) according to an illustrated embodiment of this application is shown. Each of the thyristor current interruptors 100a, 100b may have a similar Figure 2 The configuration of the thyristor current interruptor 100 depicted herein can be modified to accommodate three-phase currents, as previously discussed. Additionally, as shown, according to the illustrated embodiment, the first thyristor current interruptor 100a of the static transfer switch 132 can be electrically coupled to a first power source 134a, and the second thyristor current interruptor 100b of the static transfer switch 132 can be electrically coupled to a second power source 134b. Additionally, the first power source 134a and the second power source 134b can be different power sources. For example, according to some embodiments, the first power source 134a can be a utility power source or a grid power source, while the second power source can be an auxiliary power source or a backup power source (such as, for example, a power source provided by a battery and / or generator) and other types of power sources. According to some embodiments, such a static transfer switch 132 can be used in at least some critical situations where the load needs to be supplied with electrical power relatively continuously. For example, according to some embodiments, the output line 136 of the static transfer switch 132 may be coupled to a power distribution unit 138 (PDU), which includes, for example, a delta-to-star transformer that may be coupled to a data center, a telecommunications center and / or multiple databases or servers, and other components.

[0054] according to Figure 6 The exemplary static changeover switch 132 shown allows a first thyristor current interruptor 100a to be electrically coupled to a first power source 134a via a first input line 140a, and a second thyristor current interruptor 100b to be electrically coupled to a second power source 134b via a second input line 140b. Additionally, each of the first and second input lines 140a and 140b can be connected to an associated input-side sensor 142a, 142b, such as, for example, a voltage sensor. Each of the input-side sensors 142a, 142b can be communicatively coupled to a controller 112, allowing information detected by the input-side sensors 142a, 142b to be transmitted to the controller 112. Additionally, the first and second thyristor current interruptors 100a and 100b can be output lines 136 coupled to the static changeover switch 132. Additionally, one or more output-side sensors 144a, 144b (such as, for example, output current sensors and / or output voltage sensors) may be coupled to output line 136 and communicatively coupled to controller 112.

[0055] According to this embodiment, during normal operation, the first thyristor current interruptor 100a of the static transfer switch 132 can be operated, for example, to close, such that electrical power can be supplied from the first power source 134a to the load side of the static transfer switch 132 via the output line 136, while the second thyristor current interruptor 100b is inactive, for example, in an open state, such that electrical power from the second power source 134b is not supplied to the load side of the static transfer switch 132. The controller 112 can be combined with the detection of power events to monitor at least one or more input-side sensors 142a, 142b and / or one or more output-side sensors 144a, 144b, such as, for example, loss of power supply from the first power source 134a, or quality problems with the electrical power supplied by at least the first power source 134a, and other power events that may cause the power of the first power source 134a (if any) to be unacceptable to the relevant load. Upon detecting such a power event, controller 112 may initiate operation of auxiliary shutdown unit 104 of the first thyristor current interruptor 100a for each phase, in order to achieve a result possibly similar to that described above regarding at least Figures 3 to 4f The discussed example accelerates the turn-off of the associated main thyristor 102. The controller 112 can then initiate the operation of the second thyristor current interruptor 100b, such as, for example, closing the second thyristor current interruptor 100b, so that power from the second power source 134b can then be output from the static switching switch 132.

[0056] By accelerating the turn-off speed of the first thyristor current interruptor 100a via the operation of the corresponding auxiliary turn-off unit 104, the duration of the switching time associated with the static transfer switch 132 switching between output power from the first power source 134a and output power from the second power source 134b via the operation of the second thyristor current interruptor 100b can be reduced. This reduction in switching time can have numerous benefits, including, for example, reducing the duration during which electrical power is not supplied to the load from either the first power source 134a or the second power source 134b during the switching period, reducing downstream effects or potential damage associated with power interruption to the load, and / or reducing the size and cost of one or more capacitors for the downstream load that would otherwise be designed to provide sufficient power to the load during the switching duration from the first power source 134a to the second power source 134b.

[0057] After the first thyristor current interruptor 100a is turned off and while electrical power from the second power source 134b is being output from the static transfer switch 132, the controller 112 can continue to monitor the quality and / or availability of power from the first power source 134a. Upon determining that power from the first power source 134a is available and / or has sufficient quality, the controller 112 can similarly initiate the operation of the auxiliary turn-off unit 104 of the second thyristor current interruptor 100b, so as to also be similar to the above description regarding at least Figures 3 to 4f The example discussed accelerates the shutdown of the associated main thyristor 102 of the second thyristor current interruptor 100b. Then, the controller 112 can initiate the operation of the first thyristor current interruptor 100a, such as, for example, closing the first thyristor current interruptor 100a so that power from the first power source 134a can again be output through the static transfer switch 132.

[0058] Figure 7 A block diagram of an exemplary thyristor current interruptor 100 according to an illustrated embodiment of this application is shown, which is used in conjunction with a microgrid circuit breaker 146. Similar to... Figure 6 Each of the first thyristor current interruptors 100a and the second thyristor current interruptor 100b is a thyristor current interruptor. Figure 7The thyristor current interruptor 100 in the example provided is also configured for three-phase current applications. As shown, at least when used as a microgrid circuit breaker 146, the thyristor current interruptor 100 can be connected to a common power source 148 at a common coupling point 152 (PCC) and connected to the microgrid 150 via, for example, a distributed generation (“DG”) system 154. According to some embodiments, utilizing the thyristor current interruptor 100 of this application in conjunction with the microgrid circuit breaker 146 can result in the main thyristor 102 of the thyristor current interruptor 100 isolating the microgrid 150 from the common power source 148 at a speed approximately 20 times faster than conventional thyristor-based microgrid circuit breakers.

[0059] Figures 8 to 10 The diagram illustrates exemplary variations in the configuration of auxiliary turn-off units 104', 104', 104"' of the thyristor current interruptors 100', 100"', 100"' of this application. For example, Figure 8 The auxiliary shutdown unit 104' shown is similar to the one described above regarding at least Figure 2 The auxiliary turn-off unit 104 described differs in that, unlike the resonant inductor 124 (L) therein, r Located outside the thyristor bridge Figure 2 different, Figure 8 The resonant inductor 124 (L) in the illustrated embodiment r Located inside the thyristor bridge and connected to the second low-voltage capacitor (C) r2 ) in series. However, Figure 2 The operating principles of the auxiliary shutdown unit 104 and the auxiliary shutdown unit 104' may be the same.

[0060] about Figure 9 The auxiliary shutdown unit 104 shown includes an auxiliary semiconductor switch 118 (such as, for example, an IGBT (S) shown). a )) and four auxiliary thyristor switches 116a-d(S r1 To S r4 (A total of 5 switches) Figure 2 The auxiliary shutdown unit 104 is different. Figure 9 The auxiliary shutdown unit 104 shown has two auxiliary semiconductor switches 156a and 156b (S r1 S r2 ) and two auxiliary thyristor switches 116c, 116d (S) r3 S r4 (A total of four switches). Furthermore, although... Figure 9The embodiments depicted illustrate IGBTs with two auxiliary semiconductor switches 156a and 156b, and their use is discussed below. However, various other types of semiconductor switches may also be used, including but not limited to MOSFETs and / or JFETs, as well as other types of fully controllable semiconductor switches with full current turn-off capability. Further, from Figure 2 The first auxiliary thyristor switch 116a and the second auxiliary thyristor switch 116b of the embodiment shown are illustrated. r1 S r2 )exist Figure 9 In the illustrated embodiments, IGBT switches 156a and 156b are used instead. Compared to using at least thyristor switches, since IGBTs 156a and 156b can be turned off via a signal from controller 112 instead of waiting or current zero-crossing, this provides advantages over waiting or current zero-crossing. Figure 9 The illustrated embodiment includes two additional IGBT switches 156a and 156b (S). r1 S r2 Other types of semiconductor switches can improve the turn-off speed of the thyristor current interruptor 100, which is related to the use of thyristor switches. Furthermore, such as Figure 9 As shown, the auxiliary shutdown unit 104” may also include a third capacitor 158, and the voltage clamping unit 126 may include a voltage clamping unit pair 126a, 126b.

[0061] Turning Figure 10 , Figure 10 Describing something similar to the above about Figure 8 and Figure 9 The auxiliary shutdown unit 104" discussed is a combination of auxiliary shutdown units 104' and 104" and is therefore similar to the auxiliary shutdown unit 104". Figure 9 The auxiliary shutdown unit 104 shown is shown. Figure 10 The auxiliary shutdown unit 104" shown also includes a first auxiliary semiconductor switch and a second auxiliary semiconductor switch (such as, for example, IGBT switches 156a, 156b) having current shutdown capability. r1 S r2 Other types of semiconductor switches, replacing the first auxiliary thyristor switch 116a, the second auxiliary thyristor switch 116b, and the two auxiliary thyristor switches 116c and 116d (S r3 S r4 (A total of four switches). Therefore, since the auxiliary IGBT switches 156a and 156b can be turned off via a signal from the controller 112, the auxiliary turn-off unit 104”' can have at least the same turn-off speed as the thyristor current interruptor 100. Figure 9 The auxiliary shutdown unit 104 shown has the same benefits. Additionally, Figure 10The auxiliary shutdown unit 104" shown also includes Figure 8 At least regarding the resonant inductor 124(L) inside the thyristor bridge r The auxiliary shutdown unit 104' shown in the figure has the following features.

[0062] While the invention has been described in conjunction with embodiments currently considered to be the most practical and preferred, it should be understood that the invention is not limited to the disclosed embodiments, but rather is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which are to be interpreted in the broadest possible sense to cover all such modifications and equivalent structures permitted by law. Furthermore, it should be understood that while the use of the terms “preferred,” “ideally,” or “preferred” in the foregoing description indicates that such described features may be more desirable, it may not be essential, and any embodiment lacking the same features may be contemplated within the scope of the invention, defined by the appended claims. When reading the claims, it is intended that the use of words such as “a,” “an,” “at least one,” and “at least a portion” is not intended to limit the claims to only one, unless expressly stated otherwise in the claims. Further, when the language “at least a portion” and / or “a portion” is used, unless expressly stated otherwise, the item may include a portion and / or the entire item.

Claims

1. A device for interrupting current, comprising: The main thyristor includes at least one main thyristor switch; as well as An auxiliary turn-off unit is connected in parallel with the main thyristor, and the auxiliary turn-off unit includes: One or more pairs of auxiliary switches, each pair of auxiliary switches including a first auxiliary switch located on a first branch and a second auxiliary switch located on a second branch connected in parallel with the first branch. Multiple capacitors are located on a third branch connected in parallel with the first and second branches. A semiconductor switch is located across at least one of the first capacitors of the plurality of capacitors connected in parallel with the third branch, and At least one voltage clamping unit is located across at least one first capacitor among the plurality of capacitors connected in parallel with the third branch and the semiconductor switch. The auxiliary shutdown unit is configured to divert the load current from the main thyristor to the auxiliary shutdown unit when the semiconductor switch and the first pair of auxiliary switches transition from an off state to an on state. The plurality of capacitors includes at least one second capacitor configured and positioned to provide a resonant current to generate a current zero-crossing point for the main thyristor after the commutation of the load current to the auxiliary turn-off unit, so as to transition the main thyristor from a thyristor-on state to a thyristor-off state. At least one of the plurality of capacitors, the first capacitor is positioned and configured to have an increased voltage level due to the commutation of the load current from the semiconductor switch to the at least one first capacitor when the semiconductor switch is switched to the off state and the main thyristor is in the thyristor off state. The at least one voltage clamping unit is configured to draw electrical power from the at least one first capacitor at least until the load current through the pair or more auxiliary switches is reduced to a level capable of at least switching the first pair of auxiliary switches to the off state.

2. The apparatus of claim 1, wherein the auxiliary shutdown unit further comprises a resonant inductor, and wherein the auxiliary shutdown unit is configured to limit the rate of current rise when the load current is switched from the at least one main thyristor switch of the main thyristor to the pair or more pairs of auxiliary switches and the semiconductor switch of the auxiliary shutdown unit.

3. The apparatus of claim 2, wherein the auxiliary shutdown unit is configured to conduct resonant current through the pair or more pairs of auxiliary switches, the at least one second capacitor, the semiconductor switch, and the resonant inductor while the load current is being reversed.

4. The apparatus of claim 1, wherein the at least one second capacitor is pre-charged, and wherein the semiconductor switch has a current-off capability.

5. The apparatus of claim 1, wherein the at least one second capacitor is further positioned and configured to provide a reverse bias voltage to the main thyristor to maintain the main thyristor in the thyristor off state.

6. The apparatus of claim 1, wherein the at least one first capacitor of the plurality of capacitors is configured to limit the voltage change rate of the main thyristor when the semiconductor switch is switched from the on state to the off state.

7. The apparatus of claim 1, wherein the at least one voltage clamping unit comprises a plurality of metal oxide rheostats.

8. The apparatus according to claim 1, wherein the pair or more pairs of auxiliary switches include a first pair of auxiliary switches and a second pair of auxiliary switches, the second pair of auxiliary switches being connected in series with the first pair of auxiliary switches on the first branch and the second branch.

9. The apparatus of claim 8, wherein the at least one main thyristor switch comprises a first main thyristor switch and a second main thyristor switch, and wherein the pair or more auxiliary switches further comprises a second pair of auxiliary switches, the second pair of auxiliary switches comprising a third auxiliary thyristor switch and a fourth auxiliary thyristor switch.

10. The apparatus of claim 1, wherein the first pair of auxiliary switches comprises an auxiliary thyristor switch and an auxiliary semiconductor switch having current-cutting capability.

11. A method for interrupting current by a thyristor current interruptor, the method comprising: The semiconductor switch of the auxiliary turn-off unit of the thyristor current interrupter and the first pair of auxiliary switches among a plurality of auxiliary switches are activated. The auxiliary turn-off unit is coupled in parallel to the main thyristor. The plurality of auxiliary switches include the first pair of auxiliary switches and the second pair of auxiliary switches. Each pair of auxiliary switches includes a first auxiliary switch located on a first branch and a second auxiliary switch located on a second branch in parallel with the first branch. The semiconductor switch is located across the first capacitor among a plurality of capacitors. The plurality of capacitors are located on a third branch in parallel with the first branch and the second branch. The load current is switched from the main thyristor of the thyristor current interrupter to the auxiliary turn-off unit, wherein the main thyristor includes at least one main thyristor switch. The resonant current is transmitted by the second capacitor of the plurality of capacitors through at least a portion of the auxiliary turn-off unit in such a manner as to at least reduce the load current through the main thyristor. The semiconductor switch of the auxiliary shutdown unit is deactivated, wherein deactivating the semiconductor switch causes the voltage level of the first capacitor to increase due to the load current commutating to the first capacitor; Power is drawn from the first capacitor by one or more voltage clamping units to reduce the load current through one or more pairs of auxiliary switches; as well as When the load current in the auxiliary shutdown unit drops below the holding current or when the current crosses zero, at least the first pair of auxiliary switches in the auxiliary shutdown unit are deactivated.

12. The method of claim 11, wherein the step of activating the semiconductor switch comprises: Activate at least one of the following: the auxiliary insulated gate bipolar switch (IGBT) of the auxiliary turn-off unit, the auxiliary GTO, the auxiliary IGCT, the auxiliary BJT, the auxiliary MOSFET, and the auxiliary JFET.

13. The method of claim 12, further comprising the step of: A reverse bias voltage is applied from the second capacitor of the auxiliary shutdown unit to the at least one main thyristor switch.

14. The method of claim 13, further comprising: A reverse bias voltage from the second capacitor is applied to the auxiliary turn-off unit to provide the main thyristor with time to block the forward system voltage.

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