Patent Description:
Many electrical devices such as appliances are powered by AC voltage. In some situations, a condition can exist for such an AC voltage, and such a condition can be undesirable and potentially damaging to electrical devices.

United States Patent Application <CIT> discloses an overcurrent protection device coupled between an input terminal and an output terminal of a computing device.

In accordance with an aspect of the present invention, there is provided a protective circuit according to claim <NUM>.

In accordance with a further aspect of the present invention, there is provided an electrical apparatus according to claim <NUM>.

For purposes of summarizing the disclosure, certain aspects, advantages and novel features of the inventions have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment of the invention. Thus, the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

The headings provided herein, if any, are for convenience only and do not necessarily affect the scope or meaning of the claimed invention.

<FIG> depicts a configuration (<NUM> and/or <NUM>) in which a device or circuit (<NUM>, <NUM>) being powered by an alternating-current (AC) source (<NUM>, <NUM>) can be protected a protective circuit (<NUM> and/or <NUM>) having one or more features as described herein. Accordingly, the device or circuit (<NUM>, <NUM>) can be considered to be a protected device or circuit.

In various examples disclosed herein, the configuration (<NUM> and/or <NUM>) can be implemented in different manners. For example, the protective circuit (<NUM> and/or <NUM>) can be implemented to be substantially outside of an apparatus having the protected device or circuit (<NUM>, <NUM>), partially outside and partially within an apparatus having the protected device or circuit (<NUM>, <NUM>), substantially within an apparatus having the protected device or circuit (<NUM>, <NUM>), or any combination thereof.

Also, in various examples disclosed herein, the configuration (<NUM> and/or <NUM>) of <FIG> is sometimes described as a circuit. It will be understood that such a circuit can be implemented in, for example, a system, in an apparatus, in an electrical circuit, or some combination thereof. Accordingly, such a circuit or configuration may also be referred to as a system, an apparatus, or an electrical circuit.

Also, in various examples disclosed herein, the protected device or circuit (<NUM>, <NUM>) of <FIG> is sometimes referred to herein as a protected circuit or simply as a circuit. It will be understood that such a circuit can be an electrical circuit, an electrical device, or some combination thereof.

<FIG> generally relate to a first example configuration <NUM>, according to embodiments of the present invention, and <FIG> generally related to a second example configuration <NUM> not falling within the scope of the claims. In some examples, a configuration having one or more features as described herein can include a combination having one or more features of the first example configuration <NUM> and one or more features of the second example configuration.

Disclosed herein are embodiments of the present invention related to a combination of an assembly having gas discharge tube (GDT) and metal-oxide varistor (MOV) functionality and an arc fault circuit interrupter (AFCI), to provide an overvoltage protection functionality. Such an overvoltage protection functionality can be effective against events such as alternating-current (AC) line voltage swells.

<FIG> shows an example circuit <NUM> in which an AC power from an AC source <NUM> is being utilized to provide power to a circuit <NUM> to be protected. For the purpose of description, such a circuit can be considered to be a protected circuit due to an overvoltage protection functionality associated with the circuit <NUM>. It will be understood that the protected circuit <NUM> can include one or more load circuit that utilize AC power, one or more load circuits that utilize DC power, or any combination thereof.

In the example of <FIG>, the AC source <NUM> is shown to be coupled to the protected circuit <NUM> through an arc fault circuit interrupter (AFCI). In some embodiments, an assembly <NUM> having gas discharge tube (GDT) and metal-oxide varistor (MOV) functionalities can be provided across the protected circuit <NUM>, so as to be parallel with the protected circuit <NUM>. Examples of such a GDT+MOV assembly are described herein in greater detail.

It is noted that a typical AFCI can be configured to interrupt an AC circuit based on sensing of high frequency components associated with arcs caused by, for example, poor electrical connections. In some embodiments, and as described herein, the AFCI <NUM> of <FIG> can be configured to sense a signature generated during the operation of the GDT+MOV assembly <NUM>. Based on such a sensed signature, the AFCI <NUM> can be activated so as to interrupt the AC power being delivered from the source <NUM> to the other side of the AFCI <NUM>.

In some embodiments, the foregoing signature associated with the operation of the GDT+MOV assembly <NUM> can include one or more short-lived pulses having high frequency characteristics. Accordingly, if such a high frequency component is utilized, the AFCI <NUM> can be configured to be activated based on sensing of such a high frequency signature associated with the GDT+MOV assembly <NUM>.

In some embodiments, the AFCI <NUM> can be configured to be activated based on a typical arc condition (e.g., resulting from a poor electrical connection) or the signature associated with the operation of the GDT+MOV assembly <NUM>. In some embodiments, the AFCI <NUM> can be configured to be activated based the signature associated with the operation of the GDT+MOV assembly <NUM>, but not a typical arc condition (e.g., resulting from a poor electrical connection).

Configured in the foregoing manner, <FIG> shows an example of a normal operating condition for the circuit <NUM> of <FIG>. In <FIG>, AC power from the AC source <NUM> is being delivered to the protected circuit <NUM>. Accordingly, a normal AC current <NUM> is shown to be provided to the protected circuit <NUM> through the AFCI <NUM>. In such a state, the GDT+MOV assembly <NUM> remains inactive. States of the various components of the circuit <NUM> corresponding to <FIG> are provided in Table <NUM>.

<FIG> shows an example of an overvoltage condition such as an AC voltage swell that results in the GDT+MOV assembly <NUM> being activated so as to divert power away from the protected circuit <NUM>. Accordingly, in <FIG>, a current <NUM> is allowed to pass through the GDT+MOV assembly <NUM>, thereby providing protection for the circuit <NUM>. States of the various components of the circuit <NUM> corresponding to the condition of <FIG> are provided in Table <NUM>.

In the example of <FIG>, the current <NUM> resulting from the activation of the GDT+MOV assembly <NUM> is shown to include a main component and a high frequency (HF) component. <FIG> shows an example of a signal <NUM> corresponding to the current (<NUM> in <FIG>) passing through the GDT+MOV assembly <NUM>. More particularly, the example signal <NUM> is a voltage trace that includes a main component and a short-duration high frequency component <NUM> at an overvoltage condition associated with the signal <NUM>.

Referring to <FIG> and <FIG>, when the AFCI <NUM> detects the presence of a high frequency component (such as the HF component <NUM> in the example of <FIG>), it (AFCI <NUM>) can be activated to interrupt the AC power from the source <NUM>. Accordingly, in Table <NUM>, the state of the AFCI <NUM> in <FIG> can be a transition state where the AFCI is being activated.

<FIG> shows an example where the AFCI <NUM> has been activated as a result of the sensing of the high frequency signal component associated with the GDT+MOV assembly <NUM>. Accordingly, in <FIG>, the AFCI <NUM> uncouples the source side from the circuit side. States of the various components of the circuit <NUM> corresponding to the condition of <FIG> are provided in Table <NUM>.

In the example of <FIG>, the circuit <NUM> being interrupted by the AFCI <NUM> results in power being substantially absent on the circuit side. Accordingly, in such a condition, the GDT+MOV assembly <NUM> can reset itself and become inactive.

In some embodiments, the circuit <NUM> in <FIG> can remain in the interrupted state until the AFCI <NUM> is reset (e.g., manually or with some control signal, after the overvoltage condition is no longer present). Once reset, the AFCI <NUM> can be in the inactive state, and thus allow power to be provided to the circuit side for operation of the protected circuit <NUM>.

<FIG> show non-limiting examples of a GDT+MOV assembly that can be utilized in the circuit of <FIG>. <FIG> shows that in some embodiments, a GDT+MOV assembly <NUM> having one or more features as described herein can include a GDT device <NUM> and an MOV device <NUM>, with each being a separate device. Such separate devices can be connected in series with a conductor <NUM>. Accordingly, one end of the GDT+MOV assembly <NUM> can be connected through a conductor <NUM>, and the other end can be connected through a conductor <NUM>.

<FIG> shows that in some embodiments, a GDT+MOV assembly <NUM> having one or more features as described herein can include a GDT device <NUM> and an MOV device <NUM>, combined together in a single packaged device. For example, a terminal or an electrode of the GDT device <NUM> can be in physical and electrical contact with a terminal or an electrode of the MOV device <NUM>. Accordingly, one end of the GDT+MOV assembly <NUM> can be connected through a conductor <NUM>, and the other end can be connected through a conductor <NUM>.

<FIG> shows a more specific example of the GDT+MOV assembly <NUM> of <FIG> also shows that in some embodiments, a GDT+MOV assembly <NUM> having one or more features as described herein can include one or more GDTs and one or more MOVs. For example, the GDT+MOV assembly <NUM> of <FIG> is shown to include a series combination of MOV+GDT+MOV. Additional details concerning such a configuration are disclosed in International Application No. <CIT>, entitled INTEGRATED DEVICE HAVING GDT AND MOV FUNCTIONALITIES, the disclosure of which is hereby expressly incorporated by reference herein in its entirety.

<FIG> shows that in some embodiments, a GDT+MOV assembly <NUM> having one or more features as described herein can include an integration of one or more parts associated with one or more GDTs and one or more MOVs. For example, the GDT+MOV assembly <NUM> of <FIG> can provide a functionality of a series combination of MOV+GDT+MOV similar to <FIG>, but with some parts being shared. Additional details concerning such a configuration are disclosed in the above-referenced International Application No. <CIT>.

<FIG> shows the circuit <NUM> of <FIG> and <FIG>. In <FIG>, such a circuit can include a protective circuit <NUM> configured to provide power from an AC source <NUM> to a protected circuit <NUM>. In some embodiments, such a protective circuit can include a GTD+MOV assembly <NUM> and an AFCI <NUM>, and be configured to operate as described herein.

<FIG> show that the protective circuit <NUM> of <FIG> can be implemented in different ways. More particularly, such a protective circuit can be implemented in a single apparatus, as parts of separate devices or systems, or any combination thereof.

For example, <FIG> shows that a protective circuit <NUM> having one or more features as described herein can be implemented in a given apparatus. In such a context, a portion to the left of the protective circuit <NUM> can be considered to be a connection component <NUM>, and a portion left of the connection component <NUM> can be considered to be an AC source <NUM>. In such a context, the protective circuit <NUM> can be configured to be capable of being connected to an AC source through a connection component.

<FIG> shows an example of an apparatus <NUM> having an arrangement of components similar to the example of <FIG>. More particularly, the apparatus <NUM> can include one or more protected circuits <NUM> that are supplied with power through a protective circuit <NUM>. The protective circuit <NUM> can include one or more features as described herein, and can be configured to provide power to the one or more protected circuits <NUM> from an AC source <NUM> that is external to the apparatus <NUM>. In the example of <FIG>, the AC source <NUM> can be, for example, an electrical outlet configured to receive an appropriately configured plug <NUM>. In some embodiments, such a plug can be connected to an electrical cord <NUM>; thus, the cord <NUM> and the plug <NUM> can be parts of an AC power connection component <NUM> associated with the apparatus <NUM>.

In some embodiments, the apparatus <NUM> of <FIG> can be any electrical device configured to be plugged into an AC outlet for operation. Such an electrical device can be, for example, a household appliance.

In another example, <FIG> shows that a protective circuit <NUM> having one or more features as described herein can be implemented partially in a given apparatus, and partially in an assembly that is more associated with an AC source. For example, an AFCI <NUM> of the protective circuit <NUM> can be in a generally fixed position relative to an AC source <NUM>. An AC outlet implemented on a wall, with the outlet including the AFCI functionality, is an example of such a configuration. In such a context, a portion indicated as <NUM> can be considered to be an AC source having partial protective functionality.

In the example of <FIG>, the GTD+MOV assembly <NUM> is shown to be implemented as part of a given apparatus <NUM>. It is noted that while such a GTD+MOV assembly can also be implemented as part of the portion <NUM>, it may be more desirable to have the GTD+MOV assembly <NUM> be configured to accommodate the electrical properties of the protected circuit <NUM> (and thus be part of the same apparatus <NUM>).

In the example of <FIG>, a portion of the protective circuit <NUM> is shown to be implemented as part of the apparatus <NUM>, and also as part that is associated with the AC source <NUM>.

Disclosed herein are examples, not falling within the scope of the claims, related to coordinated use of a crowbar circuit protection device such as an integrated surge protector (e.g., a thyristor integrated surge protector (TISP)) and a transient blocking unit (TBU), to provide a self-protecting and self-resetting overvoltage protection functionality. Such an overvoltage protection functionality can be effective against events such as lightning, sub-circuit failures, and/or alternating-current (AC) line voltage swells. It will be understood that the TISP element is an example only and other voltage protection devices (e.g., gas discharge tube (GDT), metal-oxide varistor (MOV), transient voltage suppressor (TVS), etc.) may be utilized as well.

<FIG> shows an example circuit <NUM> in which an AC power from an AC source <NUM> is being utilized to provide power to a load <NUM>. For the purpose of description, such a load can be considered to be a protected circuit due to an overvoltage protection functionality associated with the circuit <NUM>.

In the example of <FIG>, the AC source <NUM> is shown to be coupled to a power conversion component <NUM> through an AC line <NUM>. The power conversion component <NUM> can covert the AC power provided through the AC line <NUM> into a direct-current (DC) or an alternating-current (AC) power having a current I and a voltage V.

In some examples, a crowbar circuit protection device <NUM> such as an integrated surge protector (e.g., a totally integrated surge protector (TISP)) can be provided across the protected circuit <NUM>, and a transient blocking unit (TBU) <NUM> along the AC line <NUM>. Examples related to operations of the crowbar circuit protection device <NUM> and the TBU <NUM> are described herein in greater detail.

In some examples, an overvoltage protection (OVP) device <NUM> can be provided across the AC line <NUM>, such that the TBU <NUM> is between the OVP device <NUM> and the power conversion component <NUM>. Such an OVP device (<NUM>) can be activated in certain situations (e.g., an overvoltage condition arising on the AC source side). In some examples, a fuse (F1) <NUM> can be provided along the AC line <NUM>, such that the fuse <NUM> is between the OVP device <NUM> and the AC source <NUM>. Such a fuse can be activated in certain situations (e.g., a large surge on the AC source side).

In the example of <FIG>, if a surge event on the AC source side is sufficiently large, the fuse <NUM> can be tripped, and cut power to the entirety of the circuit <NUM> to the right of the fuse <NUM>. There may be a surge on the AC source side that does not trip the fuse <NUM>, but activates the OVP device <NUM>. In such a situation, current from the AC source <NUM> can be generally shunted through the OVP device <NUM> and away from the power conversion component <NUM>. In some examples, the OVP device <NUM> can be, for example, a metal-oxide varistor (MOV).

Configured in the foregoing manner, <FIG> shows an example of a normal operating condition for the circuit <NUM> of <FIG>. In <FIG>, AC power from the AC source <NUM> is being converted into DC power by the power conversion component <NUM> to provide a normal current to the load (protected circuit) <NUM>. Accordingly, a normal voltage Vnorm exists across the protected circuit <NUM>, as well as across the crowbar circuit protection device <NUM>. The crowbar circuit protection device <NUM> is inactive and essentially acts as an open circuit. States of the various components of the circuit <NUM> are provided in Table <NUM>.

<FIG> shows an example of an overvoltage condition that can arise across the protected circuit <NUM>. Such an overvoltage condition may arise due to an event on either side of the power conversion component <NUM>. Thus, for the purpose of description, it will be assumed that an overvoltage Vover across the protected circuit <NUM> results from some condition. When such an overvoltage condition occurs, the crowbar circuit protection device <NUM> becomes active and becomes conductive. Thus, a current resulting from the overvoltage condition is shunted away from the protected circuit <NUM> and routed through the crowbar circuit protection device <NUM>. Accordingly, in <FIG>, such a current being shunted through the crowbar circuit protection device <NUM> is indicated as a crowbar current. Once such a crowbar current is established, the voltage across the crowbar circuit protection device <NUM> becomes approximately zero. States of the various components of the circuit <NUM> corresponding to the condition of <FIG> are provided in Table <NUM>.

In the example of <FIG>, the conductive nature of the crowbar circuit protection device <NUM> (when activated) results in the crowbar current flowing with little or no resistance. Thus, the power conversion component <NUM> can draw an increased amount of current from the AC line <NUM> in response to the foregoing crowbar current.

<FIG> shows an example of the foregoing increased amount of current drawn in the AC line <NUM> by the power conversion component <NUM>. More particularly, such a current resulting as a response to the crowbar current is indicated as an overcurrent flowing in the AC line <NUM>. In the example of <FIG>, it is assumed that the power conversion component <NUM> does not have a current-limiting feature. States of the various components of the circuit <NUM> corresponding to the condition of <FIG> are provided in Table <NUM>.

In the example of <FIG>, the overcurrent in the AC line <NUM> is assumed to be an additional current drawn as a result of the increased current (indicated as the crowbar current). If the total current including the overcurrent in the AC line <NUM> exceeds some threshold trip current of the TBU <NUM>, the TBU <NUM> becomes active and provides a blocking functionality.

<FIG> shows an example of the TBU <NUM> being in an active state so as to block current flowing into the power conversion component <NUM>. In some examples, the TBU <NUM> in the active state can block passage of both positive and negative portions of AC current. In <FIG>, the TBU <NUM> is depicted as blocking one direction (e.g., corresponding to the positive portion) of the AC current, even though it blocks the other direction. For the purpose of description of <FIG>, however, such other direction of the AC current is assumed to be blocked from reaching the other side of the power conversion component <NUM>. More particularly, the power conversion component <NUM> may be assumed to include rectification functionality, such that only positive or negative portion of the AC power passes. Thus, even if the TBU <NUM> only blocks the positive portion, the negative portion is blocked by the power conversion component <NUM>. States of the various components of the circuit <NUM> corresponding to the condition of <FIG> are provided in Table <NUM>.

In the example of <FIG>, the TBU <NUM> being activated results in power being blocked from the AC line <NUM> to the load side of the power conversion component <NUM>. Thus, if a crowbar activating event occurred on the AC line side, no power is being provided to the load side; and the crowbar circuit protection device <NUM> can become inactive. If a crowbar activating event occurred on the load side, the crowbar circuit protection device <NUM> may remain in the active state or return to the inactive state. For example, if the crowbar activating condition remains, even after the TBU activation, the crowbar circuit protection device <NUM> can remain active to protect the load. In another example, if the crowbar activating condition is no longer present, the crowbar circuit protection device <NUM> can revert back to the inactive state.

Based on the various examples as described herein in reference to <FIG>, one can see that a protected circuit (<NUM>) that is being powered by an AC source (<NUM>) can be protected at substantially all times from an event that results in an overvoltage condition. Once such an overvoltage condition clears, the crowbar circuit protection device <NUM> can reset, and the circuit <NUM> can resume normal operation.

<FIG> shows example timing diagrams of load voltage (dashed line) and AC line current (solid line) before, during, and after an event resulting in an overvoltage condition of a load being powered through an AC line. Before time t1, the circuit <NUM> of <FIG> is shown to be in a normal operating state, with a normal load voltage being provided to the protected circuit (<NUM>). Such a load voltage results from power converted from the AC line (<NUM>).

At time t1, an overvoltage condition is shown to arise, resulting in an increase in the voltage being provided to the load. Such an increase in voltage is shown to continue until a crowbar threshold is reached at time t2. At such a time, the crowbar circuit protection device (<NUM>) becomes active and provides a low resistance shunt path, thereby decreasing the voltage being provided to the load.

As described herein, the low resistance crowbar path results in an increase in current therethrough, thereby inducing an increase in current in the AC line. Accordingly, the AC line current also increases until a TBU threshold is reached time t3. At such a time, the TBU (<NUM>) blocks the AC line current, thereby causing the AC line current to be blocked from reaching the power conversion component (<NUM>). Accordingly, the AC line current at the power conversion component, and thus the converted power, decrease to respective null levels.

In the example of <FIG>, such null levels are shown to be maintained until the overvoltage condition no longer exists, and the crowbar circuit protection device (<NUM>) and the TBU (<NUM>) are reset. At such a time (t4), the AC line current is allowed to reach a normal operating level. At time t5, load voltage can also begin to increase to its normal operating level (at time t6).

In the example of <FIG>, an event duration ΔT can be considered to begin at time t1 and end at time t6. As described herein in reference to <FIG>, such an event duration can be relatively short, long or anywhere in between. In some examples, the activation times associated with the crowbar circuit protection device (<NUM>) and the TBU (<NUM>) can be sufficiently small to provide effective protection during such various-duration events. It is noted that in some situations, the crowbar circuit protection device (<NUM>) may reset on every zero-crossing of an AC input voltage. In such a situation, the example sequence shown in <FIG> may be repeated every half-cycle or every cycle (in half-wave rectified configurations) of the AC input power.

<FIG> shows examples of events that can result in damages to circuits if not protected. For example, a short duration (ΔT<NUM>) event such as lightning can involve a large overvoltage. In another example, a sub-circuit failure can result in an overvoltage condition lasting longer (e.g., ΔT<NUM>) than the lightning example. In yet another example, in some situations, a voltage swell in an incoming line may last much longer than either of the two example durations. Such a long duration (e.g., ΔT<NUM>) of overvoltage condition may not have an overvoltage level as high as the lightning example; but can be just as damaging to a circuit.

<FIG> shows the circuit <NUM> of <FIG>. In <FIG>, such a circuit can be divided into different portions. For example, a portion can be considered to be a protective supply circuit <NUM> configured to provide power to a protected circuit <NUM>. In some examples, such a protective supply circuit can include a crowbar circuit protection device <NUM>, a power conversion component <NUM>, and a TBU <NUM>. In some examples, the protective supply circuit <NUM> may optionally include either or both of an overvoltage protection (OVP) device <NUM> and a fuse (F1) <NUM>.

In the example of <FIG>, a portion to the left of the protective supply circuit <NUM> can be considered to be a connection component <NUM>, and a portion left of the connection component <NUM> can be considered to be an AC source <NUM>. In such an example context, the protective supply circuit <NUM> can be configured to be connected to, or be capable of being connected to, a circuit (e.g., <NUM>) to be protected. The protective supply circuit <NUM> can also be connected to, or be capable of being connected to, an AC source <NUM> through a connection component <NUM>. It is noted that while various examples are described herein in the context of power being converted by power conversion component <NUM>, one or more features of the present disclosure can also be implemented in a circuit without such a conversion component. In such a configuration, power from an AC source (e.g., <NUM>) can be provided to a load circuit (e.g., <NUM>) and a corresponding crowbar circuit protection device (e.g., <NUM>) through an AC line (e.g., <NUM>).

<FIG> shows an example of an apparatus <NUM> having one or more features as described herein. In some examples, the apparatus <NUM> can include one or more protected circuits <NUM> that are supplied with power through a protective supply circuit <NUM>. The protective supply circuit <NUM> can include one or more features as described herein, and can be configured to provide power to the one or more protected circuits <NUM> from an AC source <NUM>. In the example of <FIG>, the AC source <NUM> can be, for example, an electrical outlet configured to receive an appropriately configured plug <NUM>. In some examples, such a plug can be connected to an electrical cord <NUM>; thus, the cord <NUM> and the plug <NUM> can be parts of an AC power connection component <NUM> associated with the apparatus <NUM>.

In some examples, the apparatus <NUM> can be any electrical device configured to be plugged into an AC outlet for operation. Such an electrical device can be, for example, a household appliance.

It will be understood that in some examples, at least some of the protective supply circuit <NUM> can be implemented outside of the apparatus, similar to the example described herein in reference to <FIG>.

Claim 1:
A protective circuit (<NUM>) comprising:
an AC line configured to provide power from an AC source (<NUM>);
a first protection circuit (<NUM>) coupled to the AC line and implemented to be electrically parallel with a load circuit (<NUM>), the first protection circuit configured to be in an inactive state to be substantially non-conducting when a voltage across the load circuit is in a normal range or an active state to be substantially conducting when the voltage across the load circuit has an overvoltage value greater than the normal range to shunt power away from the load circuit; and
a second protection circuit (<NUM>) implemented to be electrically between the AC source and the load circuit, the second protection circuit configured to block power from the AC source in response to a condition resulting from the first protection circuit being in the active state,
the protective circuit is characterised in that the first protection circuit is implemented as an electrically series combination of a gas discharge tube, GDT, and a metal-oxide varistor, MOV, and the second protection circuit is implemented as an arc fault circuit interrupter, AFCI, provided along the AC line and configured to block the power from the AC source upon sensing of the condition resulting from the first protection circuit being in the active state, and
in that the condition resulting from the first protection circuit being in the active state includes a high frequency component in a let-through signal.