WO2024125825A1

WO2024125825A1 - A hybrid switching device with compact arrangement and a flexibility of control therefore

Info

Publication number: WO2024125825A1
Application number: PCT/EP2023/025529
Authority: WO
Inventors: Saurabh Purkayastha; Dmitry Nitkin
Original assignee: Eaton Intelligent Power Limited
Priority date: 2022-12-17
Filing date: 2023-12-15
Publication date: 2024-06-20

Abstract

A hybrid switching device is provided comprising: a power input; a power output; a first current path between the power input and the power output, the first current path comprising at least one semiconductor power switch; a second current path between the power input and the power output, the second current path comprising an electromechanical switch; and a controller. The controller is configured to detect an electrical fault condition and configured to send control signals to the electromechanical switch to cause the hybrid switching device to operate in a first operating mode or a second operating mode by controlling the electromechanical switch to be closed or open in the absence of an electrical fault condition. In the first operating mode, the electromechanical switch remains closed in the absence of a detected electrical fault condition such that the power input and the power output are connected via the second current. In the second operating mode, the electromechanical switch remains open in the absence of a detected electrical fault condition such that the power input and the power output are connected via the first current path but not via the second current path. A power switch module and a hybrid switching device comprising a plurality of power switch modules is also provided herein.

Description

A Hybrid Switching Device with Compact Arrangement and a Flexibility of Control Therefore

Field This relates to a switching device for breaking a circuit in a fault condition, the switching device including solid state and electromechanical circuit breaking elements. Such a device is termed herein a “hybrid” switching device.

Background Electronic circuit breakers typically operate by interrupting a current path using a switching mechanism that is activated when a fault condition is detected. In electromechanical circuit breakers, the interruption is achieved by opening an electromechanical switch disposed along the current path. More recently, semiconductor switches have been used to prevent current flow in solid-state circuit breakers. The use of semiconductor switches has several advantages over electromechanical switches, such as much faster activation on detection of a fault condition and the absence of arcing during contact separation. However, solid-state switching devices have higher power losses compared to electromechanical switches when conducting power during normal operation of the device (i.e. in the absence of a fault). Hybrid circuit breakers (HCBs) combine solid-state circuit breaking elements in parallel with electromechanical circuit breaking elements in order to combine some of the advantages of both types of circuit breaking switch.

Despite the advantageous features described above, there are several problems with some known hybrid circuit breakers. While being faster to activate than an electromechanical circuit breaker, hybrid circuit breakers still have a slower activation time than solid-state only circuit breakers. It is also challenging to upgrade existing HCBs to allow for operation at higher power levels. Therefore, there is a need for an improved hybrid switching device that solves the above described problems in some known HCBs. Summary of Invention

In one aspect, a hybrid switching device is provided according to an independent apparatus claim, with optional features defined in the dependent claims appended thereto.

Described herein is a hybrid switching device. The hybrid switching device comprises a power input, a power output, a first current path between the power input and the power output, the first current path comprising at least one semiconductor power switch, a second current path between the power input and the power output, the second current path comprising an electromechanical switch, and a controller configured to detect an electrical fault condition and configured to send control signals to the electromechanical switch to cause the hybrid switching device to operate in a first operating mode or a second operating mode by controlling the electromechanical switch to be closed or open in the absence of an electrical fault condition, wherein: in the first operating mode, the electromechanical switch remains closed in the absence of a detected electrical fault condition such that the power input and the power output are connected via the second current, and in the second operating mode, the electromechanical switch remains open in the absence of a detected electrical fault condition such that the power input and the power output are connected via the first current path but not via the second current path.

In some examples, upon detecting an electrical fault condition, the controller is configured to: when in the first operating mode, turn off the at least one semiconductor power switch and open the electromechanical switch or when in the second operating mode, turn off the at least one semiconductor power switch.

In some examples, in the first operating mode, the controller is configured to: control the at least one semiconductor switch to be turned off in the absence of a detected electrical fault condition such that the power input and the power output are connected via the second current path but not via the first current path, and, upon detecting an electrical fault condition: turn on the at least one semiconductor switch such that the power input and power output are connected via both the first current path and the second current path; subsequent to turning on the at least one semiconductor switch, open the electromechanical switch such that the power input and power output are connected via the first current path but not via the second current path; subsequent to opening the electromechanical switch, turn off the at least one semiconductor switch to disconnect the power input and the power output.

In some examples, the controller is configured to control the switch to operate in the second operating mode on receiving an alert indicating a high-risk condition.

In some examples, the controller is configured to determine a current rating of a system within which the hybrid switching device is included and control the electromechanical switch to operate in the first operating mode when the current rating is above a predetermined threshold and to operate in the second operating mode when the current rating is below the predetermined threshold.

In some examples, the hybrid switching device comprises a communication module and wherein determining the current rating of a system comprises the communication module receiving an indication of the current rating of the system.

In some examples, the predetermined threshold is received as a user input via the communication module. In some examples, the hybrid switching device comprises a communication module and wherein a user input is received via the communication module indicating that the hybrid switching device should operate in either the first operating mode or the second operating mode. In some examples, the hybrid switching device comprises a current measurement module configured to measure the level of current passing through the hybrid switching device and a communication module configured to send an indication of the level of current measured by the current measurement module to an external electronic device, and wherein the controller is configured to control the electromagnetic switch to operate in either the first or the second operating mode based on a communication received from the external electronic device in response to the indication of the level of current sent to the external electronic device.

In some examples, the hybrid switching device comprises a current measurement module configured to measure the current passing through the hybrid switching device, and wherein the controller is configured to control the electromagnetic switch to operate in the second operating mode based on the measured current being below a predetermined threshold.

In some examples, the first current path is one of a plurality of first current paths each comprising a semiconductor power switch and disposed in parallel to each other and to the second current path.

In some examples, the hybrid switching device comprises at least one power switch module comprising at least two semiconductor power switches, wherein the two semiconductor power switches belong to two respective first current paths of the plurality of first current paths.

In some examples, the hybrid switching device comprises a plurality of power switch modules, each module comprising: a gate signal booster coupled to a gate terminal of each of the at least two semiconductor power switches of the power switch cell an overvoltage protection device; and a heat sink.

In another aspect, a power switch module for forming part of a modular hybrid switching device is provided according to an independent apparatus claim, with optional features defined in the dependent claims appended thereto.

The power switch module comprises: a semiconductor power switch; a first connection terminal connected to a first terminal of the semiconductor power switch; a second connection terminal connected to a second terminal of the semiconductor power switch; a gate signal booster coupled to a gate terminal of the power switch transistor; an overvoltage protection device; and a heat sink.

In some examples, each power switch module comprises: two semiconductor power switches; two first connection terminal connected to respective terminals of the two semiconductor power switches; a second connection terminal connected to second terminals of the two semiconductor power switches; and a gate signal booster coupled to the gates of the two semiconductor power switches.

In another aspect, a hybrid switching device comprising power switch modules is provided according to an independent apparatus claim, with optional features defined in the dependent claims appended thereto. The hybrid switching device comprises: a first group of power switch modules and a second group of power switch modules, each group comprising a plurality of power switch modules, wherein: a first connection terminal of each semiconductor power switch in the first group of power switch modules is connected to a first connection terminal of a respective semiconductor power switch in the second group of power switch modules; a second connection terminal of each semiconductor power switch of the first group of power switch modules is connected to a power input; and a second connection terminal of each semiconductor power switch of the second group of power switch modules is connected to a power output, thereby providing a plurality of first current paths between the power input and the power output, where each first current path comprises a semiconductor power switch from the first group of power switch modules and a semiconductor power switch from the second group of power switch modules; and an electromechanical switch disposed on a second current path between the power input and the power output parallel to first current paths.

In some examples, the hybrid switching device further comprises: a controller configured to detect an electrical fault condition and configured to send control signals to the electromechanical switch to cause the hybrid switching device to operate in a first operating mode or a second operating mode by controlling the electromechanical switch to be closed or open in the absence of an electrical fault condition, wherein: in the first operating mode, the electromechanical switch remains closed in the absence of an electrical fault condition such that the power input and the power output are connected via the second current path, and in the second operating mode, the electromechanical switch remains open in the absence of an electrical fault condition such that the power input and the power output are connected via the first current paths but not via the second current path.

In another aspect of the invention, a method of operating a hybrid switching device is provided, where the hybrid switching device comprises a power input; a power output; a first current path between the power input and the power output, the first current path comprising at least one semiconductor power switch; and a second current path between the power input and the power output, the second current path comprising an electromechanical switch, the method comprising: selecting one of a first operating mode and a second operating mode; detecting whether an electrical fault condition is occurring in a circuit; and controlling the electromechanical switch to cause the hybrid switching device to operate in the first operating mode or the second operating mode by controlling the electromechanical switch to be closed or open in the absence of an electrical fault condition, and: based on the first operating mode being selected, controlling the electromechanical switch to remain closed in the absence of a detected electrical fault condition such that the power input and the power output are connected via the second current path, and based on the second operating mode being selected, controlling the electromechanical switch to remain open in the absence of a detected electrical fault condition such that the power input and the power output are connected via the first current path but not via the second current path.

In some examples, the method further comprises changing the hybrid switching device from the first operating mode to the second operating mode by opening the electromechanical switch and turning on the at least one semiconductor power switch in the absence of a detected fault condition.

Brief Description of the Figures

The following description is with reference to the following Figures. Figure 1 shows a schematic representation of a hybrid circuit breaker (also termed herein a hybrid switching device) according to an embodiment;

Figure 2 illustrates the solid-state part of a hybrid circuit breaker according to an embodiment;

Figure 3 shows a schematic representation of control elements of a hybrid circuit breaker according to an embodiment;

Figure 4 shows a flow diagram representing a control method of a hybrid switching device in accordance with the present invention;

Figure 5 shows a flow diagram representing another control method of a hybrid switching device in accordance with the present invention; Figure 6a illustrates a schematic view of a power switch module according to an embodiment in profile view;

Figure 6b illustrates a schematic view of the power switch module of Figure 6a in plan view;

Figure 7 illustrates the connection of semiconductor power switches in two power switch modules according to an embodiment. Detailed Description of the Invention

With reference to Figure i and Figure 2, a hybrid circuit breaker too is described. The term hybrid circuit breaker (HCB) refers to circuit breaker devices that use semiconductor power switch component in combination with electromechanical circuit breaker components to control power and current flow. In the following description, an HCB is also referred to as a hybrid switching device.

The hybrid circuit breaker too comprises a plurality of parallel current paths connecting a power input 101 to a power output 102. The power input 101 maybe connected to a power source supplying AC or DC current, and the power output 102 maybe connected to a load. At least one first current path no comprises a semiconductor power switch, and a second current path 120 comprises an electromechanical switch 140. The semiconductor power switch 130 may be a metal-oxide-semiconductor field-effect transistor (MOSFET), such as a silicon carbide power switch, an insulated-gate bipolar transistor (IGBT), or another form of semiconductor based (solid-state) switching device. The electromechanical switch 140 may be an electromechanical relay. In the particular embodiment discussed with reference to the figures, the hybrid circuit breaker 100 comprises four first current paths no in parallel, each first current path comprising (or defined through) two semiconductor power switches 130. One second current path 120 is provided in parallel to the first current paths, the second current path having one electromechanical switch 140 disposed thereon. In general, any number of first current paths 110 can be provided in order to achieve suitable current transmission capacity for a given application. A surge protection device 170, such as a metal oxide varistor (MOV), maybe disposed in parallel to the first and second current paths. Any surge protection device 170 maybe used in place of the MOV shown.

The first current paths are provided in a modular solid-state part 100a of the hybrid circuit breaker, illustrated in Figure 2. In the embodiment of Figure 1 and Figure 2, four power switch modules 500 are provided, each comprising two semiconductor power switches 130. The four power switch modules are divided into a first group 501, in which semiconductor power switches 130 are connected to the power input 101, and a second group 502, in which semiconductor power switches 130 are connected to the power output 102. Semiconductor power switches 130 from the first group 501 are connected to a respective semiconductor power switch in the second group 502 to form a first current path between the power input 101 and the power output 102. The power switch modules 500 and their arrangement are described in detail with reference to Figures 6a, 6b and 7. It will be understood that although the first current paths 110 are described here as being defined through a modular solid-state part 100a, in other implementations (not illustrated), the solid-state part of the hybrid switching device may not be modular.

The hybrid circuit breaker too comprises a controller 150, shown schematically in Figure 3, which is able to send control signals to turn the semiconductor power switches 130 on or off and control signals to open or close the electromechanical switch 140. The controller 150 is also able to detect an electrical fault condition in the circuit (i.e. the circuit that the HCB is deployed in) by directly detecting the fault condition or receiving an alert indicating the fault condition. The hybrid circuit breaker too may include a current measurement module 180 that determines the amount of current passing through the hybrid circuit breaker, and the controller 150 may detect a short circuit or overcurrent condition by measuring a current flowing through the hybrid circuit breaker which exceeds a predetermined threshold for the system. The controller may detect a residual current through one or more residual current devices coupled to the circuit. Alternatively, a separate detection element of the hybrid circuit breaker too may send a trigger alert to the controller 150 upon detecting an electrical fault condition. The controller 150 may comprise one or more distinct elements of circuitry and measurement devices. The hybrid circuit breaker too also comprises a communication module 160. The communication module 160 allows communication with external electronic devices, such as a mobile device 200. The communication module 160 may include a Bluetooth communication module 161 and/or a WiFi communication module 162 for communicating with an external electronic device 200 (in this example, a mobile computing device). The communication module 160 can be configured to communicate with the external electronic device 200 and/or the controller 150 (and/or with any other module) over any suitable connection. The connection can be a wired connection or a wireless connection, as appropriate. In other words, a signal can be transmitted from/received at the communication module 160 using any suitable communication protocol, and over any suitable connection or network arrangement. For example, wireless embodiments maybe deployed in 2G/3G/4G/5G networks and further generations of 3GPP, but also in non-3GPP radio networks such as WiFi (as illustrated in Figure 3 with communication module 162). Names of network elements, protocols, and methods are based on current standards. In other versions or other technologies, the names of these network elements and/or protocols and/or methods maybe different, as long as they provide a corresponding functionality.

The hybrid circuit breaker too can operate in two distinct modes, which correspond to a hybrid switching mode and solid-state only switching mode. In a first operating mode, which is the hybrid switching mode, the electromechanical switch 140 is closed during normal operation of the device. Normal operation of the device is considered to be a state in which current is conducted between the input and the output without any electrical fault condition being detected by the controller 150. In other words, in the first operating mode, the electromechanical switch remains closed in the absence of a detected electrical fault condition. Preferably, the semiconductor power switches 130 are turned off in the absence of a fault condition in the first operating mode. As such, in the first operating mode, an electrical current flows the second current path 120 in the absence of an electrical fault condition. In embodiments where the semiconductor power switches 130 are turned on in the absence of a fault condition, the majority of the current flow remains in the second current path due to the greater resistance of the semiconductor power switches in comparison to the electromechanical switches.

When the controller 150 detects an electrical fault condition, the power input is disconnected from the power output. In embodiments in which the semiconductor switches 130 are turned on during normal operation of the device, both the first and second current paths are interrupted by turning off the semiconductor power switches 130 and opening the electromechanical switch 140. This may be performed by first opening the electromechanical switch 140 and then turning off the semiconductor power switches 130 when sufficient separation between the contacts of the electromechanical switch 140 have been achieved to avoid massive arcing (the formation of a high-voltage electrical arc requiring substantial arc quenching devices). In particular, as the electromechanical switch begins to open, low-voltage arcing occurs between the contacts of the electromechanical switch 140, and the increased resistance of the second current path causes current to be diverted along the first current paths while the electromechanical switch opens. The time required for disconnecting the power supply is therefore limited by the mechanical process of opening the electromechanical switch 140 and achieving suitable separation between the electromechanical switch contacts. In embodiments in which the semiconductor switches are turned off during normal operation of the device, the second current path is interrupted by opening the electromechanical switch 140. This may be performed by first turning on the semiconductor switches 130, and opening the electromechanical switches 140 once the semiconductor switches are turned on. Turning on the semiconductor switches 130 before opening the electromechanical switch 140 allows the electromechanical switch 140 to be opened without excessive arcing as current can be diverted along the first current paths. When sufficient contact separation has been achieved at the electromechanical switch 140, the semiconductor switches 130 are then turned off, achieving disconnection of the power input and the power output.

In the second operating mode, which is the solid-state only switching mode, the electromechanical switch 140 is open during normal operation of the device. In other words, the electromechanical switch remains open in the absence of a detected fault condition, and current flows between the power input and the power output via only the first current paths 110 and not the second current path 120. When the controller 150 detects an electrical fault condition, the first current paths 110 are interrupted by turning off the semiconductor power switches 130 disposed on each of the first current paths 110. Because the second operating mode is solid-state only, with no contact separation (no moving parts), arcing does not occur during interruption of the current paths. The semiconductor power switches 130 can be turned off immediately on detection of the electrical fault condition. Therefore, the time required to achieve disconnection of the power supply in the second operation mode is limited only by the time to turn off the semiconductor power switches 130. Because the time taken to achieve interruption using the solid-state only mode is significantly shorter than the time required to achieve sufficient separation of the electromechanical switch contacts to avoid massive arcing, the second operating mode allows significantly faster disconnection of a power supply than the first operating mode. However, because semiconductor power switches 130 generally have significantly greater conduction losses than electromechanical switches 140, the second operating mode has greater susceptibility to power loss and thermal runaway. Therefore, it is preferred to operate in the first operating mode when the hybrid circuit breaker too is used to conduct large currents, and in the second operating mode when the hybrid circuit breaker too is used to conduct lower currents. The second operating mode is also be preferred in situations where rapid disconnection of a power supply under fault conditions is required. For example, where a leak of a flammable gas is detected in the vicinity of the hybrid circuit breaker too, the second operating mode may be used in order to reduce arcing during disconnection of the power supply should a fault condition occur and thereby reduce the likelihood of combustion of the flammable gas.

The controller 150 may control the hybrid circuit breaker too to operate in the first operating mode or the second operating mode by controlling the electromechanical switch 140 to be closed or open during normal operation of the device (i.e. in the absence of a detected electrical fault condition). In order to operate in the first operating mode, the controller 150 controls the electromechanical switch 140 to be closed in the absence of a detected electrical fault condition. In the first operating mode, the electromechanical switch 140 is only opened when an electrical fault condition is detected. In order to operate in the second operating mode, the controller 150 controls the electromechanical switch 140 to be open regardless of whether an electrical fault condition is detected.

In one embodiment, described with reference to Figure 4, the controller 150 controls the electromechanical switch 140 to operate in the first or the second operating mode in response to a signal received from a mobile device 200. Although a mobile device 200 is used in this example, it will be understood that any suitable external electronic device 200 maybe used in place of the mobile device.

In step 401, in order to set an operating mode of the hybrid circuit breaker too, a user uses a mobile device 200 to connect to the communication module 160 of the hybrid circuit breaker too using e.g. Bluetooth or WiFi communications with the communication module 160 of the hybrid circuit breaker too. Any other suitable communication protocols may be used instead of (or as well) as WiFi and Bluetooth, as appropriate to the architecture of the communication module 160. In step 412, the mobile device receives an indication of a risk. The indication of a safety risk maybe an alert that there is a high risk of an accident in relation to electrical faults. For example, the alert may indicate that there is a high likelihood of a fault taking place based on prognostic analysis of a system in which the circuit breaker is placed.

Alternatively, the alert may indicate that a leak of flammable gas has been detected that could cause an increased risk of an explosion caused by the presence of arcing in the case of disconnection of the electromechanical switch in the first operating mode under a fault condition.

If the mobile device 200 determines that the safety risk is low, in step 403, the mobile device sends a signal to the controller 150 to indicate that the hybrid circuit breaker too should operate in the first operating mode. In response to the signal, the controller 150 causes the hybrid circuit breaker too to operate in the first operating mode by controlling the electromechanical switch 140 to be closed unless an electrical fault current is detected. If the mobile device 200 determines that the safety risk is high, in step 404, the mobile device sends a signal to the controller 150 to indicate that the hybrid circuit breaker too should operate in the second operating mode. In response to the signal, the controller 150 causes the hybrid circuit breaker too to operate in the second operating mode by controlling the electromechanical switch 140 to be open in the absence of an electrical fault current.

In another embodiment, described with reference to Figure 5, the controller 150 controls the electromechanical switch 140 to operate in the first or the second operating mode in response to a signal received from a mobile device 200. Although a mobile device 200 is used in this example, it will be understood that any suitable external electronic device 200 may be used in place of the mobile device.

In step 411, in order to set an operating mode of the hybrid circuit breaker too, a user uses a mobile device 200 to connect to the communication module 160 of the hybrid circuit breaker too using e.g. Bluetooth or WiFi communications with the communication module 160 of the hybrid circuit breaker too. Any other suitable communication protocols may be used instead of (or as well) as WiFi and Bluetooth, as appropriate to the architecture of the communication module 160. The hybrid circuit breaker too determines the field amperage of the circuit using the current measurement module 180 of the of the hybrid circuit breaker too. The field amperage measurement is sent to the mobile device 200 using the established Bluetooth or WiFi connection. Any measurement/indication of current or of a level of current may be used instead of (or as well as) the field amperage. In step 412, the mobile device receives an indication of the measured field amperage (and/or other measurement/indication of current) and determines whether the value of the measured field amperage is greater or lesser than a predetermined threshold value, Ithreshold* The predetermined threshold value is set or determined to be less than a current level indicative of a fault current, such as an overcurrent or a short circuit current. The predetermined threshold may be set by a manufacturer of the device or by a user. For example, a user may input the predetermined threshold on the mobile device and send an indication of this threshold to the controller 150 of the hybrid circuit breaker too via the communication module 160. The predetermined threshold value may be chosen to be current below which it is preferred to operate in the solid-state only operating mode and above which it is preferred to operate in the hybrid operating mode. For example, the predetermined threshold maybe chosen such that the current passing through each semiconductor power switch 130 is below a current rating of the semiconductor power switches 130. As such, the predetermined threshold may depend on the total number of first current paths 110 in the solid-state part 100a of the semiconductor device and the current capacity of the semiconductor power switches 130 disposed in each first current path 110. If the mobile device 200 determines that the measured field amperage is greater than the predetermined threshold value, in step 413, the mobile device sends a signal to the controller 150 to indicate that the hybrid circuit breaker too should operate in the first operating mode. In response to the signal, the controller 150 causes the hybrid circuit breaker too to operate in the first operating mode by controlling the electromechanical switch 140 to be closed unless an electrical fault current is detected.

If the mobile device 200 determines that the measured field amperage is less than the predetermined threshold value, in step 414, the mobile device sends a signal to the controller 150 to indicate that the hybrid circuit breaker too should operate in the second operating mode. In response to the signal, the controller 150 causes the hybrid circuit breaker too to operate in the second operating mode by controlling the electromechanical switch 140 to be open in the absence of an electrical fault current.

In other embodiments, different methods may be used to select the operating mode of the hybrid circuit breaker.

In one embodiment, the controller 150 has a predetermined current threshold stored thereon. This predetermined threshold may be communicated to the controller by the mobile device 200 based on a user input or circuit design parameters. When the controller 150 measures or determines that field amperage is greater than the predetermined threshold, the controller 150 controls the electromechanical switch 140 to be closed in the absence of a measured electrical fault condition. In other words, the hybrid circuit breaker operates in the first operating mode. When the controller 150 measures or determines that field amperage is less than the predetermined threshold, the controller 150 controls the electromechanical switch 140 to be open in the absence of a measured electrical fault condition. In other words, the hybrid circuit breaker too operates in the second operating mode.

In another embodiment, the controller receives a current rating for the system via the communication module 160. The current rating may be provided by the mobile device.

If the current rating is greater than a predetermined threshold, the controller 150 controls the electromechanical switch 140 to be closed in the absence of a measured electrical fault condition. When the controller 150 measures that field amperage is less than a predetermined threshold, the controller 150 controls the electromechanical switch 140 to be open in the absence of a measured electrical fault condition. The predetermined threshold maybe provided as a user input at the mobile device 200 or may be set by manufacturers of the device.

In another embodiment, the controller 150 selects the operating mode based on known prognostic fault detection methods. For example, the controller 150 may select the operating mode based on harmonic content in the current signature of the load profile (i.e. by analysing the current drawn by the load connected to power output 102). The controller 150 may, for example, operate in the second operating mode if harmonic content in the current signature of the load profile indicates the presence of an electronic fault in the load in order to allow rapid disconnection of the power supply if a fault condition is detected. In one aspect of the disclosure, the hybrid circuit breaker too is provided in a modular form. In particular, the solid-state part 100a of the hybrid circuit breaker too is formed of a plurality of connected power switch modules 500. The provision of the hybrid circuit breaker too in a modular form allows the solid-state part 100a of the hybrid circuit breaker too to be built (or assembled) to match the power supply requirements of the particular system in which it is being used. For example, a user can assemble a desired number of power switch modules 500 for a particular application.

Furthermore, this modular approach allows the current capacity of the hybrid circuit breaker too to be upgraded by including additional power switch modules 500 to an existing hybrid circuit breaker in accordance with the invention. In the example embodiments described above with reference to Figures 1-4, the hybrid circuit breaker too comprises four power switch modules 500 (though it will be understood that the hybrid circuit breaker described herein could be implemented with a single solid-state switching part).

Figures 6a and 6b illustrate an individual power switch module 500 (or “power switch cell”) of the solid-state part 100a of the hybrid circuit breaker too. The power switch module 500 comprises two semiconductor power switches 130 disposed in parallel, though the number of semiconductor power switches maybe different in other embodiments. Each semiconductor power switch 130 may be a metal- oxide-semiconductor field-effect transistor (MOSFET), such as a silicon carbide power switch, an insulated-gate bipolar transistor (IGBT), or another form of semiconductor based (solid state) switching device. The semiconductor power switches are preferably provided in discrete transistor packages, such as TO-247 transistor packages. The power switch module 500 comprises two first connection terminals 560, each first connection terminal being coupled to a drain of a respective semiconductor power switch 130. The power switch module 500 comprises a second connection terminal 570 coupled to the source of both of the two semiconductor power switches 130. A gate signal booster 540 (or buffer) is connected to the gate of both semiconductor power switches 130. Each power switch module 500 is associated with an over-voltage protection device 550, such as a metal oxide varistor (MOV) or a transient voltage suppressor (TVS). Each semiconductor switch 130 is mounted on a heat sink 530. The solid-state part of the hybrid circuit breaker too is built from a plurality of individual power switch modules 500. The power switch modules 500 are separated into two groups. For power switch modules 500 in the first group 501, the second connection terminals 570 of each of the semiconductor power switches 130 are connected to the power input 101. For power switch modules 500 in the second group 502, the second connection terminals 570 of each of the semiconductor power switches 130 are connected to the power output 102.

The first connection terminal 560 of each semiconductor power switch 130 in the first group 501 of power switch modules 500 is connected to the first connection terminal

560 of a respective semiconductor power switch 130 of the second group 502 of power switch modules 500, as illustrated in Figure 6. A plurality first current paths 110 between the power input and the power output is thereby formed, where each first current path comprises a semiconductor power switch 130 from the first group of power switch modules and a semiconductor power switch 130 from the second group of power switch modules in a back-to-back arrangement. The number of first current paths can be chosen by connecting a suitable number of power switch modules 500.

Laminated copper busbars 190 are used to connect the first connection terminals of the semiconductor power switches 130 in this example. As the electrical connections between semiconductor power switches 130 are not formed as part of a printed circuit board (i.e. there are no pre-printed conductive traces between the respective power switches 130), there is significant flexibility in the arrangement and connections of power switch modules 500. A flexible, modular switching device may therefore be provided.

A first gate driver circuit (not shown) controls the gate electrodes of the semiconductor power switches 130 of the first group 501 of power switch modules 500, and a second gate driver circuit (not shown) controls the gate electrodes of the semiconductor power switches 130 of the second group 502 of power switch modules 500. The first and second gate driver circuits form part of the controller 150, or may receive control signals from the controller 150.

Figure 7 illustrates the connection between two power switch modules 500. In the embodiments described above, each power switch module 500 comprises two semiconductor power switches 130. Each semiconductor power switch 130 of a power switch module 500 of the first group 501 of power switch modules is connected to a semiconductor power switch 130 of a power switch module 500 of the second group 502 of power switch modules. However, the two semiconductor power switches 130 of a given power switch module 500 (of the first group) are not necessarily connected to two semiconductor power switches 130 of the same power switch module 500 of the second group. For example, as seen in the embodiment shown in Figure 2, a first semiconductor power switch 130 of a first power switch module 500 may be connected to a semiconductor power switch 130 of a second power switch module, while a second semiconductor power switch 130 of the first power switch module 500 may be connected to a semiconductor power switch 130 of a third power switch module 500. This arrangement is facilitated by the use of different shapes of busbar 190. Preferably, the connections between semiconductor power switches 130 in the first and second group of power switch modules should be chosen such that all of the first current paths have substantially equal total resistances. As such, the current distribution across the semiconductors will be substantially uniform, which reduces the possibility of localized temperature rises and thermal runaway at a given semiconductor power switch.

In an alternative embodiment, each power switch module 500 comprises two semiconductor power switches 130 connected in series. A second connection terminal 570 of a first semiconductor power switch 130 is connected to the power input 102 and a second connection terminal 570 of a second semiconductor power switch 130 is connected to the power output. Each power switch module 500 is associated with one first current path 110 in this embodiment. Additional first current paths 110 can be provided by connecting additional power switch modules 500 between the power input and the power output in parallel with each other.

An electromechanical switch 140, which forms the electromechanical part of the hybrid circuit breaker, is connected in parallel to the above described arrangement of power switch modules 500 to form a hybrid circuit breaker. The electromechanical switch 140 and the semiconductor power switches 130 are controlled in a first operating mode or a second operating mode by way of a controller 150, as described above with e.g. reference to Figure 4 and Figure 5.

The modular hybrid circuit breaker and control methods described above provide a modular, scalable and volume-optimized hybrid switching device that can be controlled to operate in different operating modes for improved performance under different power supply conditions. The hybrid circuit breaker (or hybrid switching device) described herein may be implemented as part of any electrical apparatus or device, or in any suitable electrical circuit. It is noted herein that while the above describes various examples of the circuit breaker of the first aspect, this description should not be viewed in a limiting sense.

Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

Claims

1. A hybrid switching device configured to operate in a first operating mode and a second operating mode, the hybrid switching device comprising: a power input; a power output; a first current path between the power input and the power output, the first current path comprising at least one semiconductor power switch; a second current path between the power input and the power output, the second current path comprising an electromechanical switch; and a controller configured to: select one of the first operating mode and the second operating mode; detect whether an electrical fault condition is occurring in a circuit; and send control signals to the electromechanical switch to cause the hybrid switching device to operate in the first operating mode or the second operating mode by controlling the electromechanical switch to be closed or open in the absence of an electrical fault condition, wherein: the controller is configured to control, based on the first operating mode being selected, the electromechanical switch to remain closed in the absence of a detected electrical fault condition such that the power input and the power output are connected via the second current path, and the controller is configured to control, based on the second operating mode being selected, the electromechanical switch to remain open in the absence of a detected electrical fault condition such that the power input and the power output are connected via the first current path but not via the second current path.

2. The hybrid switching device of claim 1, wherein the controller is configured to control the at least one semiconductor power switch to be turned on in the absence of a detected electrical fault condition, and upon detecting an electrical fault condition, the controller is configured to: based on the first operating mode being selected, turn off the at least one semiconductor power switch and open the electromechanical switch; or based on the second operating mode being selected, turn off the at least one semiconductor power switch.

3. The hybrid switching device of claim 1, wherein the controller is configured to: based on first operating mode being selected: control the at least one semiconductor power switch to be turned off in the absence of a detected electrical fault condition such that the power input and the power output are connected via the second current path but not via the first current path, and upon detecting an electrical fault condition: turn on the at least one semiconductor power switch such that the power input and power output are connected via both the first current path and the second current path; subsequent to turning on the at least one semiconductor power switch, open the electromechanical switch such that the power input and power output are connected via the first current path but not via the second current path; subsequent to opening the electromechanical switch, turn off the at least one semiconductor power switch to disconnect the power input and the power output; and based on second operating mode being selected: control the at least one semiconductor power switch to be turned on in the absence of a detected electrical fault condition such that the power input and the power output are connected via the first current path but not via the second current path and, upon detecting an electrical fault condition, turn off the at least one semiconductor power switch.

4. The hybrid switching device of any preceding claim, wherein the controller is configured to select the second operating mode on receiving an alert indicating a high- risk condition.

5. The hybrid switching device of any of claims 1 to 3, wherein the controller is configured to determine a current rating of a system within which the hybrid switching device is included and control the electromechanical switch to select the first operating mode when the current rating is above a predetermined threshold and to select the second operating mode when the current rating is below the predetermined threshold.

6. The hybrid switching device of claim 5, wherein the hybrid switching device comprises a communication module and wherein the controller is configured to determine the current rating of a system based on the communication module receiving an indication of the current rating of the system.

7. The hybrid switching device of claim 6, wherein the predetermined threshold is received as a user input via the communication module.

8. The hybrid switching device of any of claims 1 to 3, wherein the hybrid switching device comprises a communication module and wherein the controller is configured to select one of a first operating mode and a second operating mode based on a user input being received via the communication module indicating that the hybrid switching device should operate in either the first operating mode or the second operating mode.

9. The hybrid switching device of any of claims 1 to 3, wherein the hybrid switching device comprises: a current measurement module configured to measure a level of current passing through the hybrid switching device; and a communication module configured to send an indication of the level of current measured by the current measurement module to an external electronic device, and wherein the controller is configured to select either the first or the second operating mode based on a communication received from the external electronic device in response to the indication of the level of current sent to the external electronic device.

10. The hybrid switching device of any of claims 1 to 3, wherein the hybrid switching device comprises a current measurement module configured to measure the current passing through the hybrid switching device, and wherein the controller is configured to select the second operating mode based on the measured current being below a predetermined threshold and select the first operating mode based on the measured current being above the predetermined threshold.

11. The hybrid switching device of any preceding claim, wherein the first current path is one of a plurality of first current paths, each first current path comprising a semiconductor power switch and disposed in parallel to each other and to the second current path.

12. The hybrid switching device of claim 11, comprising at least one power switch module, each power switch module comprising at least two semiconductor power switches, wherein the two semiconductor power switches belong to two respective first current paths of the plurality of first current paths.

13. The hybrid switching device of claim 12, comprising a plurality of power switch modules, each power switch module comprising: a gate signal booster coupled to a gate terminal of each of the at least two semiconductor power switches of the power switch module; an overvoltage protection device; and a heat sink.

14. A method of operating a hybrid switching device comprising: a power input; a power output; a first current path between the power input and the power output, the first current path comprising at least one semiconductor power switch; and a second current path between the power input and the power output, the second current path comprising an electromechanical switch, the method comprising: selecting one of a first operating mode and a second operating mode; detecting whether an electrical fault condition is occurring in a circuit; and controlling the electromechanical switch to cause the hybrid switching device to operate in the first operating mode or the second operating mode by controlling the electromechanical switch to be closed or open in the absence of an electrical fault condition, and: based on the first operating mode being selected, controlling the electromechanical switch to remain closed in the absence of a detected electrical fault condition such that the power input and the power output are connected via the second current path, and based on the second operating mode being selected, controlling the electromechanical switch to remain open in the absence of a detected electrical fault condition such that the power input and the power output are connected via the first current path but not via the second current path.

15. The method of claim 14, further comprising changing the hybrid switching device from the first operating mode to the second operating mode by opening the electromechanical switch and turning on the at least one semiconductor power switch in the absence of a detected fault condition.