Hybrid Circuit Breaker with Improved Current Capacity per Unit Size

Abstract

A hybrid circuit breaker (1) comprises an electromechanical bypass switch (S1), a semiconductor circuit (5) connected in parallel with the electromechanical bypass switch (S1), and a control unit (CTRL). The control unit (CTRL) controls the commutation from a current path (4a, 4b) in which the electromechanical bypass switch (S1) is arranged to the semiconductor circuit (5) when the electromechanical bypass switch (S1) is open. In addition, the hybrid circuit breaker (1) includes an effective cooling device (F, 17) near the electromechanical bypass switch (S1) for cooling the movable elements (12, 15) of the electromechanical bypass switch (S1). Furthermore, a method for operating a hybrid circuit breaker (1) of the type described above and a type series of hybrid circuit breakers (1) having different rated current capacities and / or different current-time characteristics is disclosed.

Description

Field of the Invention

[0001] The present invention relates to a hybrid circuit breaker, comprising at least two input connectors for receiving electrical power from an electrical grid, at least two output connectors for transmitting electrical power to a load, and current paths each connecting an input connector and an output connector. Furthermore, the hybrid circuit breaker comprises a (high-speed) electromechanical bypass switch in at least one of the current paths and a (power) semiconductor circuit in parallel with the electromechanical bypass switch. In particular, the semiconductor circuit can be implemented as a bidirectional power semiconductor circuit. The control unit of the hybrid circuit breaker is capable of controlling, in the case of a switching operation (e.g., at rated current, fault current, or overcurrent), the commutation from the current path in which the electromechanical bypass switch is arranged to the semiconductor circuit via the electromechanical bypass switch. In particular, the current commutation is achieved by generating an arc voltage between the contacts of the electromechanical bypass switch. Furthermore, the present invention relates to a series or group of hybrid circuit breakers of a type as described above, wherein the various hybrid circuit breakers of the series or group of the type have different rated current capacities and / or different current-time characteristics. Finally, the present invention relates to a method of operating a hybrid circuit breaker of the type as described above. Background Art

[0002] Hybrid circuit breakers as defined above are generally known and are disclosed, for example, in US 9,947,496 B2. When the electromechanical bypass switch opens due to, for example, an overload situation at the output connector (e.g., due to an arc fault or short circuit in the load or the circuit connecting the load), the current passing through the switch contacts of the electromechanical bypass switch is passed through or commutated to the semiconductor circuit. Specifically, when the contacts of the electromechanical bypass switch open, an arc voltage is generated between their contacts, causing the current commutation from the bypass switch to the semiconductor switch. After the current commutation, the current passing through the hybrid circuit breaker no longer flows through the electromechanical bypass switch but to the semiconductor circuit. By these measures, the harmful effects of the switching arc on the switch contacts are reduced in a timely manner, and thus the impact on the contacts is limited. Thus, the hybrid circuit breaker combines the advantages of an electromechanical circuit breaker, which provides a very low on-state resistance but is prone to damage to the switch contacts due to a large number of arcs, and the advantages of a solid-state circuit breaker, which has no mechanical switch contacts but has a relatively high on-state resistance.

[0003] Furthermore, EP 2 750 257 B1 discloses a hybrid circuit breaker, specifically an HVDC circuit breaker or switching device that can be used in point-to-point and multi-terminal high-voltage direct current (HVDC) power collection, transmission, and distribution networks.

[0004] Typically, one drawback of a hybrid circuit breaker is that it becomes bulky when it has to conduct a large rated current, because the semiconductor circuit has to withstand very high overcurrents and fault currents. Therefore, it also has to absorb very high electrical energy, which results in significant electrical stress on the components of the hybrid circuit breaker, especially on the semiconductor circuit. In addition, the electrical energy is converted into heat energy in the semiconductor circuit, which has to be absorbed and dissipated. In common concepts, the semiconductor circuit is made very large so that it can withstand such high overcurrents and fault currents. Therefore, as described above, the hybrid circuit breaker becomes bulky at high currents.

[0005] Cooling of the semiconductor circuit is in principle also possible, but technically complex and challenging. The reason is that the heat energy is generated very quickly, in other words, the thermal power is very high, and cooling has to be carried out near the junction of the semiconductor components to be effective. Generally, the outer surface of a common housing is not suitable for cooling, due to the thermal resistance between the junction and the outer surface, and due to the heat capacity of the housing. In other words, cooling through the outer surface is too slow.

[0006] It should also be noted that the above problems increase more than linearly with the rated current, because in addition to the increased current, the high-speed electromechanical bypass switch also slows down. The reason is that the conductive and movable components have to be heavier to handle higher currents and are thus heavier. Consequently, due to the increased mass of the movable contacts of the electromechanical bypass switch, the commutation of the current occurs later and takes longer. This is why the stress on the semiconductor circuit increases linearly with the rated current.

[0007] In the above context, it should be noted that when an arc fault or short circuit occurs, the current does not immediately reach its maximum level, but instead rises sharply due to the grid impedance. Since it takes some time to open the contacts to achieve a sufficient mechanical distance to establish the required dielectric strength, the semiconductor circuit conducts the worse part of the overload, i.e., the part with the higher current. It is easy to understand that the longer the time required for the current to commutate to the semiconductor circuit, the worse the situation becomes.

[0008] Considering other parts of the hybrid circuit breaker, such as a varistor switched in parallel with the electromechanical bypass switch, the same problems also occur.

[0009] In summary, the advantages of the hybrid circuit breaker over the electromechanical circuit breaker and the solid-state circuit breaker decrease with increasing rated current, and there are technical and economic limitations to the use of the hybrid circuit breaker. Summary of the Invention

[0010] Accordingly, the problem of the present invention is to provide an improved hybrid circuit breaker. In particular, the size and cost of the semiconductor circuit of the hybrid circuit breaker should be reduced, especially for high rated currents. In particular, the technical and economic limitations of using the hybrid circuit breaker should be shifted to higher rated currents without increasing the size and cost of the hybrid circuit breaker.

[0011] The problem of the present invention is solved by the following hybrid circuit breaker.

[0012] A hybrid circuit breaker comprising

[0013] - an input connector that receives electrical energy from the power grid,

[0014] - an output connector that transmits electrical energy to a load,

[0015] - current paths, each current path connecting the input connector and the output connector,

[0016] - an electromechanical bypass switch in at least one of the current paths,

[0017] - a semiconductor circuit in parallel with the electromechanical bypass switch, and

[0018] - a control unit that is capable of controlling, in the case of a switching operation, the commutation from the current path in which the electromechanical bypass switch is arranged to the semiconductor circuit, characterized in that the circuit breaker further comprises: an effective cooling device located near the electromechanical bypass switch for cooling the movable element of the electromechanical bypass switch.

[0019] Furthermore, the problem of the present invention is solved by a type of series or group of hybrid circuit breakers comprising various hybrid circuit breakers of the above kind having different rated current capacities and / or different current-time characteristics (tripping characteristics).

[0020] Finally, the problem of the present invention is solved by a method of operating a hybrid circuit breaker of the above kind, wherein the movable element of the electromechanical bypass switch is effectively cooled by an effective cooling device arranged near the electromechanical bypass switch.

[0021] Advantageously, the thermal coupling between the effective cooling device and the electromechanical bypass switch, especially its movable element, is higher than the thermal coupling between the effective cooling device and the semiconductor circuit. In short, the cooling is concentrated on the electromechanical bypass switch, especially its movable element.

[0022] By means of the above measures, the hybrid circuit breaker can generally withstand higher overcurrents and be used for higher rated currents without increasing the size of the semiconductor circuit. In addition, the technical and economic limitations of using hybrid circuit breakers are shifted to higher rated currents. Therefore, a wider range of electrical devices can benefit from the advantages of hybrid circuit breakers. In addition, a specific type or specific size of hybrid circuit breaker can cover a larger current-time characteristic (tripping curve). Therefore, a series or group of hybrid circuit breakers of one type can be composed of a smaller number of different types or different sizes of hybrid circuit breakers, including various hybrid circuit breakers, and the various hybrid circuit breakers cover all the required current-time characteristics.

[0023] Surprisingly, cooling the electromechanical bypass switch is more effective than cooling the semiconductor circuit. Cooling the electromechanical bypass switch is also not as technically complex as cooling the semiconductor circuit. The temperature reduction at the semiconductor circuit achieved in this way is extremely high compared to conventional designs, even higher than when using a cooling device acting directly on the semiconductor circuit. In fact, the proposed measures specifically reduce the electrical stress on the semiconductor circuit.

[0024] The reason is that the electromechanical bypass switch has movable elements (e.g., pivot levers or contact arms), which must have a larger cross-section to carry higher currents. This has an adverse and unintended effect on the current that the semiconductor circuit must carry and the electrical energy that the semiconductor circuit must convert into heat energy in the case of an overcurrent event or a fault current event. Because the larger the movable elements of the electromechanical bypass switch, the slower they move under the same actuating force. This results in a considerable delay until the moving switch contacts of the electromechanical bypass switch lift off from their fixed switch contacts, and thus also a considerable delay until the semiconductor circuit receives current from the electromechanical bypass switch and reaches a sufficient mechanical distance to avoid reigniting the switching arc. The rapid and sharp current rise in the case of an arc fault or a short circuit combined with the said delay results in a significant increase in the current that the semiconductor circuit must carry, leading to an increase in the electrical energy that the semiconductor circuit must convert into heat energy in the case of an overcurrent event or a fault current event, and leading to a significant increase in the electrical stress in the semiconductor material. In other words, the delay in the mechanical movement of the switch contacts leads to a delay in current commutation, resulting in a higher current value on the semiconductor circuit and also a longer duration to reach the required contact separation to turn off the semiconductor circuit. Finally, the semiconductor circuit will carry a higher current for a longer time. As mentioned above, due to this delay phenomenon, the problems in the semiconductor circuit increase disproportionately (i.e., more than linearly) with the rated current.

[0025] By cooling the electromechanical bypass switch, its movable element can be made smaller, lighter, and can move faster than without cooling. As a result, the contact opening time is shortened, and the size and cost of the semiconductor circuit are reduced. Thus, the amazing effect of this hybrid circuit breaker is based on the fact that heat energy is not removed from the semiconductor circuit to a great extent by cooling, but rather heat energy, especially electrical stress, is actually avoided. In other words, the leverage effect between the cooling electromechanical bypass switch and the multiplication effect on the semiconductor circuit is utilized. Only low cooling power is required, so only a small cooling device is needed to achieve a large effect.

[0026] For the same effect, cooling the semiconductor circuit without cooling the electromechanical bypass switch would require much higher cooling power and a much larger cooling device. Additionally, as mentioned above, cooling the semiconductor circuit is technically complex and challenging because it must occur close to the junction of the semiconductor element to be effective. Therefore, the proposed cooling of the electromechanical bypass switch is not only more effective but also simpler.

[0027] In other words, when increasing the rated current of the hybrid circuit breaker, maintaining the temperature of the electromechanical bypass switch also keeps the current interruption ability at substantially the same level, thereby also keeping the cost and space of the hybrid circuit breaker at substantially the same level. Specifically, by using the above measures, the electromechanical bypass switch can withstand higher currents without increasing the size, mass, and inertia of the movable switch contacts of the electromechanical bypass switch. By keeping the mass and inertia of the movable switch contacts at the same level, the opening speed of the bypass switch also remains the same. Therefore, the fault magnitude or overcurrent magnitude of the semiconductor circuit used in the hybrid circuit breaker also remains at the same level. Looking at it from the opposite perspective, this also means faster interruption, lower cost, and smaller space at the same rated current.

[0028] An additional effect of cooling the electromechanical bypass switch is to reduce the loop inductance of the hybrid circuit breaker by reducing the size of the semiconductor circuit, especially by reducing the effective area of the semiconductor element. Reducing the loop inductance of the hybrid circuit breaker in turn means reducing the current commutation time from the electromechanical bypass switch to the semiconductor circuit. The reduced current commutation time also means that the adverse effect of the arc voltage on the mechanical switch contacts of the electromechanical bypass switch is smaller. In other words, the proposed measures allow for higher currents without shortening the service life of the hybrid circuit breaker.

[0029] Considering other parts of the hybrid circuit breaker, such as considering the varistor in parallel with the electromechanical bypass switch, very similar advantages are also provided.

[0030] Therefore, the small cooling device has multiple effects on the hybrid circuit breaker.

[0031] Finally, a hybrid circuit breaker with such a cooling function can have the same size for higher rated currents and can cover a larger current-time characteristic (tripping curve) than the prior art, or can be made smaller than the prior art at the same rated current. Doubling the rated current usually means doubling the size of the semiconductor circuit, thus doubling the cost of the semiconductor circuit, and quadrupling the volume of the varistor switched in parallel with the electromechanical bypass switch, thus quadrupling the cost of the varistor. By using only a small cooling device, this "rule" can be broken.

[0032] In an advantageous embodiment,

[0033]

[0034] where A is the effective chip area of the semiconductor circuit in cm 2 , n is the number of power switching elements (such as diodes, transistors, thyristors, etc.) in the semiconductor circuit, I cu is the short-circuit current switching capacity of the hybrid circuit breaker in amperes, and di is the current density of a single power switching element in A / cm 2 . For a single power switching element and a typical current density di = 150 A / cm 2 , this particularly means:

[0035] A < 0.0017 [cm 2 A -1 ·I cu

[0036] And for a typical short-circuit current switching capacity I cu = 20 kA,

[0037] A < 34.0 cm 2

[0038] If the semiconductor circuit includes four non-controlled power switching elements (diodes) and one controlled power switching element (transistor, thyristor), then n = 5 and the total effective chip area of the semiconductor circuit is less than 5·34.0 cm 2 = 170.0 cm 2 . If there are four controlled power switching elements with freewheeling diodes, then n = 4 and the total effective chip area of the semiconductor circuit is below 4·34.0 cm 2 = 136.0 cm 2It should be noted in the above context that implementing the power switching element through multiple parallel-connected power switching elements does not significantly increase the size of the semiconductor circuit. Therefore, in an embodiment of a semiconductor circuit including four uncontrolled power switching elements and one controlled power switching element, if the controlled power switching element is implemented by two or more smaller transistors or thyristors switched in parallel, for example, the statement n = 5 still holds. This also applies to the uncontrolled power switching elements.

[0039] In the above formula, the current density of the semiconductor circuit is related to the effective chip area of a single power switching element. However, the semiconductor chip must be attached to an isolated substrate and interconnected by bonding wires. In addition, the electronic circuit requires a housing. Therefore, if the current density related to the housing of the semiconductor circuit is used, the above coefficients 0.25 and 0.0017 must be increased. Accordingly, the above typical current density di = 150 A / cm 2 refers to the effective chip area of a single power switching element, and the current density corresponding to the housing of the semiconductor circuit is correspondingly smaller. It should also be noted that the current density di = 150 A / cm 2 is related to the silicon chip, and the current densities of different technologies may deviate from the above values.

[0040] It should also be noted that the term 0.25·I cu is generated by a current rise dl / dt of 10 A / μs and a time span of 500 μs (10 A / μs · 500 μs = 0.25 - 20 kA), during which the current flows through the semiconductor circuit (the time span is t4 in the figure). Other values may lead to different results. Therefore, the term dl / dt - t4 can be used as the numerator in the above formula, resulting in

[0041]

[0042] In addition, it is advantageous that

[0043]

[0044] where V is the volume of the varistor switched in parallel with the electromechanical bypass switch, in cm 3 , I cu is the short-circuit current switching capacity of the hybrid circuit breaker, in amperes, dE is the energy density of the varistor, in J / cm 3 , where the energy density dE refers to the effective volume of the varistor. For a typical energy density dE = 250 J / cm 3 , this particularly means:

[0045] V < 1·02·10 -4 [cm 3 A-1 ·I cu

[0046] And for a typical short - circuit current switching capacity I cu = 20 kA,

[0047] V < 2.04 cm 3

[0048] In the above formula, the energy density of the varistor is related to the effective varistor volume, i.e., in the case of a metal - oxide varistor (MOV), the volume of the metal - oxide material. Therefore, if the energy density related to the varistor housing is used, the above factors 2.54·10 -2 and 1.02·10 -4 . Therefore, the above - mentioned typical energy density dE = 250 J / cm 3 refers to the effective varistor volume, and the energy density of the varistor housing is correspondingly smaller.

[0049] It should also be noted that the term 2.54·10 -2 [HA]·I cu is generated by a current rise dl / dt of 10 A / μs and a time span of 527 μs and an inductance L = 36.6 μH. During the time span, the current flows through the semiconductor circuit (the time span is t4 in the figure), and the inductance is selected according to the standard IEC60947 - 1 (E = 0.5·36.6 μH(10 A / μs·527 μs) 2 = 2.54·10 -2 ·20 kA) for I cu = 20 kA and a 50 - Hz power grid. Other values may lead to different results. Therefore, the term 0.5·L·(dl / dt·t4) 2 can be used as the numerator in the above formula, resulting in

[0050]

[0051] Advantageously, when the effective cooling device is turned on with a constant rated current, the temperature of the movable element of the electromechanical bypass switch is reduced by approximately at least 10 °C. In this way, a significant effect on reducing the electrical stress and thermal stress of the semiconductor circuit can be achieved.

[0052] The "movable element" is an element of the electromechanical bypass switch that moves relative to the fixed contacts of the electromechanical bypass switch when the switch state of the electromechanical bypass switch changes between the "ON (open)" state and the "OFF (closed)" state. In particular, the movable element includes a movable switch contact and a lever or a disk, and the movable switch contact is mounted on the lever or the disk or is part of the movable switch contact.

[0053] In the context of the present invention, "for cooling a movable element" means that an effective cooling device in an on state draws heat away from the movable element of the electromechanical bypass switch, in particular by heat transfer, heat convection, and / or heat radiation. For example, the cooling surface of the effective cooling device may be attached to the movable element of the electromechanical bypass switch to cool it substantially by heat transfer. The cooling surface of the effective cooling device may also be arranged near the movable element of the electromechanical bypass switch to cool it substantially by heat radiation. In addition, the effective cooling device may generate a flow of cooling fluid that is directed across the movable element of the electromechanical bypass switch to cool the movable element substantially by heat convection.

[0054] "Thermally coupled" can be defined by the cooling effect of the thermally coupled device, for example, by how many kelvins the thermally coupled device cools when the cooling device is in an effective state compared to an ineffective cooling device. "Thermally coupled" can also be defined by the dissipated thermal energy.

[0055] In particular, the temperature difference at the switch contact with ineffective / effective cooling is preferably greater than the temperature difference in the junction layer of the semiconductor components of the semiconductor circuit with ineffective / effective cooling. Alternatively or additionally, the energy / power dissipation at the switch contact caused by the cooling device is preferably greater than the energy / power dissipation in the junction layer of the semiconductor components of the semiconductor circuit.

[0056] "Current-time characteristic" or "tripping characteristic" represents the ability of the hybrid circuit breaker to conduct a specified level of overcurrent within a specified time span. For example, the relationship between the time before the circuit breaker trips and the current passing through the circuit breaker can be defined as a multiple of the rated current in a current-time characteristic diagram. For example, there are "B" type circuit breakers (standard), "C" type circuit breakers (elevated closing or surge current), and "D" type circuit breakers (high capacitive or inductive loads). The "D" type circuit breaker is more robust than the "C" type circuit breaker in terms of overcurrent over time, and the "C" type circuit breaker is more robust than the "B" type circuit breaker. Therefore, the "D" type circuit breaker is more suitable for heavy loads than the "C" type circuit breaker, and the "C" type circuit breaker is more suitable for heavy loads than the "B" type circuit breaker. In other words, the "D" type circuit breaker allows more overcurrent than the "C" type circuit breaker, and the "C" type circuit breaker allows more overcurrent than the "B" type circuit breaker.

[0057] In particular, the electromechanical bypass switch is implemented as a "high-speed" electromechanical bypass, which means that the switching time from powering the actuator for the movable switch contact (e.g., feeding current into the relay coil) until the total gap between the fixed switch contact and the movable switch contact is > 1.2 mm for an embodiment without an electronic bypass switch and > 0.15 mm for an embodiment with an electronic bypass switch is ≤ 1 ms (while a typical relay provides an opening time of 20 - 30 ms). The reason for the different gap values is that in the case of using an electronic bypass switch, the air between the switch contacts remains "cold", thus avoiding switch arcs, while in the case of not using an electronic bypass switch, it becomes "hot" and is ionized to generate switch arcs. In a specific embodiment, the switching time can be ≤ 400 μs (e.g., in the range of 300 - 500 μs). In particular, the time span between the time point when an electrical fault occurs and the time point when the current flowing through the semiconductor circuit drops to zero is < 450 μs. In particular, if a "high-speed" electromechanical bypass switch is used in a hybrid circuit breaker, cooling of the semiconductor circuit by the electromechanical bypass switch can be omitted. The reason is that even in the case of a high cut-off current, there is no significant temperature rise in the semiconductor circuit in a short time. In other words, the thermal coupling between the effective cooling device and the semiconductor circuit can be less than 0.05 times the thermal coupling between the effective cooling device and the electromechanical bypass switch. It should be noted that the contact gap mentioned above refers to the total gap, which is the same for a single contact pair, and the double contact pair (single) contact gap is doubled.

[0058] As described above, the "switching time" is the time from energizing the actuator for the movable switch contact until the total gap between the fixed switch contact and the movable switch contact is reached. The "fully open time" is the time required from the movable switch contact lifting off the fixed switch contact until the total gap is reached. The "contact delay" is the time from powering the actuator for the movable switch contact until the movable switch contact starts to move. In other words, this means that:

[0059] Switching time = Contact delay + Fully open time

[0060] Generally, the power of the cooling device is extremely low, in the range of a few watts. Generally, at the same rated current, the cooling power of a hybrid circuit breaker is much lower than the power loss of a solid-state circuit breaker. Therefore, adding such a low-power cooling device to a hybrid circuit breaker and using the combination instead of a solid-state circuit breaker is very economical. For example, the cooling device may have 2 W. It has been found in laboratory tests that by using a small fan, the rated current of the electromechanical bypass switch can be doubled. In other words, at the same rated current, the mass of the moving element of the electromechanical bypass switch can be halved, so that the speed of the element can be doubled.

[0061] In particular, the rated voltage of the hybrid circuit breaker is <1500 VDC or <1000 VAC RMS. When the hybrid circuit breaker is used for alternating current, it must be prepared for bidirectional current flow, which in particular means that the semiconductor circuit must be implemented as a bidirectional power semiconductor circuit. For this reason, for example, the semiconductor circuit can have a rectifier.

[0062] As described above, the switching time of the hybrid circuit breaker can be in the range of approximately 100 μs. It should also be noted in this context that the basic intention is not to cool the switching arc (if any), but rather to cool the conductive metal elements of the electromechanical bypass switch. Cooling of the switching arc may occur, but this is only a side effect.

[0063] In this context, it should also be noted that the power of the effective cooling device (e.g., 2 W) is extremely low compared to the power of the possible switching arc. For example, if the rated current of the hybrid circuit breaker is 50 A and the minimum trip current is, for example, 75 A, the switching arc power Parc is approximately

[0064] Parc = 12 V (arc voltage) x 75 A (trip current) x 0.5 = 450 W

[0065] However, the trip current can also be ten times the rated current resulting in a switching arc power of 3000 W in the above example. It should be noted that the factor 0.5 comes from the linear current ramp. In a favorable embodiment, at the minimum trip current of the hybrid circuit breaker (especially 1.5 times the rated current of the hybrid circuit breaker), the power of the effective cooling device is less than 2% of the switching arc power. In other words, Pc < 0.02 x Parc[@Itrip] or Pc < 0.03 x Parc[@Inom]

[0066] where Pc is the cooling power, Parc[@Itrip] is the switching arc power at the minimum trip current, and Parc[@Inom] is the switching arc power related to the rated current of the hybrid circuit breaker.

[0067] In particular, the (unintended) temperature reduction of the switching arc with the said low cooling power is <5 °C. In other words, the temperature of the switching arc in the on state of the effective cooling device is only less than 5 °C lower than the temperature of the switching arc in the off state of the effective cooling device.

[0068] It should also be noted that some embodiments of the electromechanical bypass switch are encapsulated, which means that the movable contact piece, the fixed switch contact, and the movable switch contact are built into an airtight space, which can be evacuated or filled with an inert gas as the case may be. In such cases, it is simply not possible to cool the switching arc.

[0069] Other advantageous embodiments are disclosed in the claims, the description and the drawings.

[0070] Advantageously, the cooling device is capable of generating a heat flow when the electromechanical bypass switch is closed and / or during more than 90% of the operating time of the hybrid circuit breaker. In this context, advantageously, when the electromechanical bypass switch is closed, the effective cooling device of the hybrid circuit breaker is in its on state; and / or during more than 90% of the operating time of the hybrid circuit breaker, the effective cooling device is in its on state. In this way, the electromechanical bypass switch is cooled during the normal operation of the hybrid circuit breaker and remains in good condition to cope with possible short circuits or arc faults. The cooling control can be a separate device or can also be integrated into the commutation control of the hybrid circuit breaker. The fan can also be directly connected to the power supply without being controlled by the cooling control.

[0071] Furthermore, advantageously, when the electromechanical bypass switch is closed and / or during more than 90% of the operating time of the hybrid circuit breaker, the effective cooling device generates a cooling fluid flow. Again, the electromechanical bypass switch is cooled during the normal operation of the hybrid circuit breaker and remains in good condition to cope with possible short circuits or arc faults.

[0072] The "operating time" in the context of the present invention is the time during which current flows (or can flow) through the electromechanical bypass switch.

[0073] Furthermore, advantageously, the effective cooling device is in its on state at least in a current range from 90% to 100% of the trip current of the hybrid circuit breaker; or the effective cooling device is in its on state at least in a current range from the rated current of the hybrid circuit breaker to the trip current of the hybrid circuit breaker. In these ways, the electromechanical bypass switch is cooled in the case of overcurrent and remains in good condition to cope with possible tripping events. The cooling control can be a separate device or can also be integrated into the commutation control of the hybrid circuit breaker. The cooling device can also be directly connected to the power supply without being controlled by the cooling controller. The above current ranges can include or exclude the trip current.

[0074] Advantageously, the cooling device is arranged in the housing of the hybrid circuit breaker, which also houses the electromechanical bypass switch and the semiconductor circuit. In this way, all necessary functions are integrated in a common single housing.

[0075] By implementing the cooling device as a fan, which is placed in the immediate vicinity of the fixed and movable switch contacts of the electromechanical bypass switch, air can be simply used as the cooling fluid, and the cooling fluid can be directed across the movable elements (including the movable switch contacts) of the electromechanical bypass switch. Advantageously, the air flow caused by the fan can also be directed across the fixed switch contacts of the electromechanical bypass switch. In this context, it is particularly advantageous to increase the air flow of the effective cooling device implemented as a fan before the electromechanical bypass switch closes. Thus, it is advantageous that the cooling controller is operably connected to the fan and is ready to increase the air flow of the fan before the electromechanical bypass switch closes. In this way, the loss of burned material can be blown away from the fixed and movable switch contacts, thereby extending the service life of the electromechanical bypass switch. It should also be noted that the fan does not need to stop during a switching arc event, but it can also (but not only) operate when a switching arc occurs. While directing the air flow over the movable elements of the electromechanical bypass switch, a fan can also be used to cool the encapsulated electromechanical bypass switch, where the movable contact blade, the fixed switch contact, and the movable switch contact are built in an airtight space. In the above context, the term "immediate vicinity" particularly refers to a distance of less than 20 mm between the fan and the fixed switch contact or between the fan and the movable switch contact.

[0076] In an alternative advantageous embodiment of the hybrid circuit breaker, the effective cooling device is implemented as a Peltier element. In this way, cooling can be achieved without moving elements.

[0077] In yet another advantageous embodiment of the hybrid circuit breaker, the cooling device is implemented as immersion cooling or a heat exchanger with a liquid heat carrier, where a barrier separates the moving elements of the electromechanical bypass switch from the liquid heat carrier. Utilizing the relatively high heat capacity of the liquid heat carrier means that a high level of cooling power can be achieved. The barrier separates the moving elements of the electromechanical bypass switch from the liquid heat carrier, enabling the moving elements to move freely (in air or in gas) and not be damped by the liquid.

[0078] In another advantageous embodiment, the hybrid circuit breaker includes an electronic bypass switch (which may also be denoted as "auxiliary semiconductor switch") connected in series with a mechanical and electrical bypass switch, wherein the series connection of the electronic bypass switch and the mechanical and electrical bypass switch is connected in parallel with a semiconductor circuit. The electronic bypass switch cuts off the current before the mechanical and electrical bypass switch opens, thereby avoiding switching arcs on the switching contacts of the mechanical and electrical bypass switch. Therefore, the service life of the mechanical and electrical bypass switch is extended. In addition, the safety air gap between the switching contacts of the mechanical and electrical bypass switch can be reached more quickly because there is no switching arc and no arc plasma between the contacts of the mechanical switch, thereby reducing the isolation ability of the air gap. In other words, the electronic bypass switch shortens the fully open time of the mechanical and electrical bypass switch because the movable switching contacts do not need to move as far. However, the semiconductor circuit should not cut off the current unless the air gap between the switching contacts of the mechanical and electrical bypass switch is large enough to withstand the peak voltage caused by the semiconductor circuit without risking flashover between the switching contacts of the mechanical and electrical bypass switch to avoid avalanche breakdown of the electronic bypass switch. Therefore, by using the electronic bypass switch, the load on the mechanical and electrical bypass switch and the semiconductor circuit can be reduced because the current through the hybrid circuit breaker is commutated to the semiconductor circuit more quickly, and thus the current level is lower than that of a hybrid circuit breaker without an electronic bypass switch.

[0079] It should be noted that in the case of using an electronic bypass switch, it is useful to cool the movable element of the mechanical and electrical bypass switch without any limitation, which avoids switching arcs on the contacts of the mechanical and electrical bypass switch because the benefits of the cooling are independent of the presence of the switching arcs.

[0080] It should also be noted at this time that the electronic bypass switch generally has an extremely low on-state resistance but a low breakdown voltage, while the semiconductor circuit has a relatively high on-resistance and a high breakdown voltage. For example, the breakdown voltage of the electronic bypass switch is 10 - 50 times smaller than that of the semiconductor circuit. Specifically, the breakdown voltage of the electronic bypass switch may be in the range of 30V, while the breakdown voltage of the main semiconductor switch may be in the range of 1200V.

[0081] When the hybrid circuit breaker is used for alternating current, the electronic bypass switch must be prepared for this. For example, it can be implemented by two anti-series transistors (specifically, two anti-series MOSFETs).

[0082] In another advantageous embodiment, the mechanical and electrical bypass switch is a multi-contact pair switch. For example, it can include two or more contact pairs, that is, two pairs of fixed and movable switching contacts. By using multiple contact pairs, multiple arcs with multiple arc voltages are generated, which shortens the turn-off and commutation times because the required safety contact gap is divided into multiple contact gaps that expand simultaneously or almost simultaneously when the switching contacts open, but at the cost of increased complexity, reduced reliability, and a slightly increased weight.

[0083] Advantageously, various hybrid circuit breakers of a series or group of hybrid circuit breaker types having different rated current capacities and / or different current-time characteristics include the same type of electromechanical bypass switch and / or the same type of semiconductor circuit. In another advantageous embodiment, the housings of various hybrid circuit breakers for a series of hybrid circuit breaker types having different rated currents and / or having different current-time characteristics have the same external dimensions. By the above measures, the number of different types of complex components of the hybrid circuit breaker, specifically, the number of different electromechanical bypass switches of a series of hybrid circuit breakers of one type and / or the number of different types of semiconductor circuits of a series of hybrid circuit breakers of one type, is reduced. Furthermore, a series / group of hybrid circuit breakers of one type having different rated current capacities and / or having different current-time characteristics can be produced with less technical effort and at lower cost.

[0084] Advantageously, various hybrid circuit breakers of a series or group of hybrid circuit breaker types include different types of cooling devices. In this way, different cooling powers can be easily achieved over a wide range of different rated current capacities and / or over a wide range of different rated current-time characteristics to achieve different rated current capacities with the same type of electromechanical bypass switch and / or semiconductor circuit.

[0085] However, it is also advantageous if various hybrid circuit breakers of a series or group of hybrid circuit breaker types include the same type of cooling device. In this case, one and the same cooling device can operate at different power levels in order to provide a cooling power suitable for a specific rated current capacity and / or a specific current-time characteristic. Alternatively, the cooling device can operate at a power level suitable for the highest rated current capacity within a group of hybrid circuit breakers using the same type of cooling device and / or the heavy current-time characteristic within the group. Thus, the cooling power for lower rated current capacities exceeds the actual requirement.

[0086] In an advantageous embodiment of a series or group of hybrid circuit breaker types,

[0087] - the first hybrid circuit breaker of a series of hybrid circuit breaker types of said type includes a cooling device and has a first rated current capacity and / or a first current-time characteristic and

[0088] - the second hybrid circuit breaker of said type without a cooling device has a second rated current capacity lower than said first rated current capacity and / or a second current-time characteristic, said second current-time characteristic being less robust than the first current-time characteristic.

[0089] This is a special case of different cooling powers of a hybrid circuit breaker, where the cooling power of one hybrid circuit breaker is zero, which means that a cooling device is not required at all. In the case of different rated current capacities, this means, for example, that the first rated current capacity can be 200 A, while the second rated current capacity can be 100 A. In the case of different current-time characteristics, the above example means that the first current-time characteristic can be a "D" trip characteristic, while the second current-time characteristic can be a "C" trip characteristic.

[0090] Generally, it is advantageous for the cooling power of the effective cooling device to increase when the current on the electromechanical bypass switch increases and / or when the current-time characteristic changes to a more robust characteristic. In this way, the cooling power can adapt to changing requirements. Specifically, when the current on the electromechanical bypass switch increases, the cooling power increases to keep the latter in good condition during a turn-off event. Alternatively or additionally, the cooling power can vary according to the current-time characteristic. It is conceivable that one and the same hybrid circuit breaker provides multiple current-time characteristics or trip characteristics, which can be selected during the setup process. For example, one of the "B", "C", or "D" type characteristics can be selected. Therefore, when there is a transition from the "B" type to the "C" type or from the "C" type to the "D" type, the cooling power can increase, and vice versa. Generally, the cooling power can vary continuously or stepwise. Preferably, the cooling power varies continuously according to the current on the electromechanical bypass switch and / or varies stepwise according to different current-time characteristics. It should be noted that providing multiple current-time characteristics in a single hybrid circuit breaker is not a necessary condition, but different hybrid circuit breakers with the same type of electromechanical bypass switch can also provide different current-time characteristics and / or the same type of semiconductor circuit, and are equipped with different types of cooling devices, or the same type of cooling device operating at different power levels. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] The present invention will now be described in more detail below with reference to specific embodiments, however, the present invention is not limited to these embodiments.

[0092] Figure 1 A circuit diagram of an exemplary hybrid circuit breaker is shown;

[0093] Figure 2 is a perspective view of a capsule bypass device with a separate cooling device;

[0094] Figure 3 is a perspective view of a bypass device with a fan;

[0095] Figure 4 A perspective view of a bypass device with a heat exchanger or a Peltier element;

[0096] Figure 5 Is a perspective view of an unencapsulated bypass device of a detachable fan;

[0097] Figure 6 Is Figure 1 Graphs of various electrical parameters of the hybrid circuit breaker under fault conditions;

[0098] Figure 7 Is a simplified equivalent circuit of the disconnecting part of the hybrid circuit breaker; and

[0099] Figure 8 Is the typical current-time characteristic or tripping characteristic of the hybrid circuit breaker. Detailed implementation

[0100] Generally, the same or similar elements are denoted by the same / similar names and reference numerals. The features disclosed in the specification apply to the elements having the same / similar names and reference numerals respectively. The indication of orientation and relative position (up, down, lateral, etc.) is related to the associated drawings, and the indication of orientation and / or relative position must be changed accordingly in different drawings depending on the situation.

[0101] Figure 1 Shows an exemplary hybrid circuit breaker 1, which includes two input connectors 2a, 2b for the power grid, two output connectors 3a, 3b for the load, and current paths 4a, 4b, each connector connecting the input connectors 2a, 2b to the output connectors 3a, 3b. In addition, the hybrid circuit breaker 1 includes an electromechanical bypass switch S1 in the current path 4a and a semiconductor circuit 5 connected in parallel with the electromechanical bypass switch S1. In Figure 1 The example of, the hybrid circuit breaker 1 includes two optional anti-series electronic bypass switches S2a, S2b (specifically, MOSFETs here) connected in series with the electromechanical bypass switch S1.

[0102] The semiconductor circuit 5 includes rectifiers D1...D4, whose inputs are connected to the series connection endpoints of the electromechanical bypass switch S1 and the electronic bypass switches S2a, S2b. In this example, two parallel transistors T1, T2 (specifically, IGBTs here) switch between the outputs of the rectifiers D1..D4. However, a different number of transistors T1, T2 can be used alternatively. In addition, an optional buffer circuit 6 is arranged in parallel with the two transistors T1, T2. The buffer circuit 6 includes a buffer resistor R1 and a buffer capacitor C connected in series and a buffer diode D5 connected in parallel with the buffer resistor R1.

[0103] The hybrid circuit breaker 1 also includes a varistor R2, which is connected to the series connection endpoints of the electromechanical bypass switch S1 and the electronic bypass switches S2a, S2b and provides overvoltage protection for them.

[0104] In addition, the hybrid circuit breaker 1 includes a shunt resistor R3, the terminals of which are connected to the input of the control unit CTRL and which is used to measure the current Ia flowing through the input connector 2a.

[0105] The control unit CTRL is not only used to measure the current Ia, but is also capable of controlling the commutation from the current path 4a, in which the electromechanical bypass switch S1 is arranged, to the semiconductor circuit 5 in the case of a switching operation (for example, in the case of an overcurrent passing through the electromechanical bypass switch S1). In particular, when the electromechanical bypass switch S1 is opened by the control unit CTRL and an arc voltage is generated, the commutation can be initiated. For this reason, the output of the control unit CTRL is connected to the input of the electromechanical bypass switch S1, the electronic bypass switches S2a, S2b and the transistors T1, T2.

[0106] In addition, the hybrid circuit breaker 1 includes switches S3, S4 in the current paths 4a, 4b, thus providing current isolation. The output of the control unit CTRL can also be connected to the input of the switches S3, S4.

[0107] Finally, the hybrid circuit breaker 1 includes an effective cooling device F, where the thermal coupling between the cooling device F and the electromechanical bypass switch S1 is higher than the thermal coupling between the cooling device F and the semiconductor circuit 5. Simply put, the cooling power is focused or concentrated on the electromechanical bypass switch S1.

[0108] In detail, the effective cooling device F is implemented here as a fan. The fan F and the electromechanical bypass switch S1 can form a combined bypass device 7. The fan F can be controlled by a cooling control CTC or can simply be connected to a power supply ( Figure 1 not shown in the figure). The cooling control CTC can be a separate device or can also be integrated into the (commutation) control unit CTRL, as is the case in the example of Figure 1 .

[0109] In general, other cooling devices in addition to the fan F can also be used to cool the electromechanical bypass switch S1, such as heat exchangers or Peltier elements (see Figure 4 ).

[0110] Figure 1 A voltage source VP is also shown in series with a series grid resistor R4 and a series grid inductor L connected to the input connectors 2a, 2b of the hybrid circuit breaker 1. At the output connectors 2a, 2b, a load 8 is connected and an electrical fault 9 is also shown, for example in the form of a short circuit or an arc flash.

[0111] The fan F is preferably arranged in the housing of the electromechanical bypass switch S1 and / or in the housing of the hybrid circuit breaker 1, which housing also houses the electromechanical bypass switch S1 and the semiconductor circuit 5.

[0112] Figure 2 and Figure 3 A first embodiment of the bypass device 7a is now shown in more detail, Figure 2 without the fan F and Figure 3 with the fan F (note that the terminals for connecting the fan F to the power supply or the cooling control CTC are not shown explicitly). The bypass device 7a includes two terminals 10a, 10b connected to the base 11. In addition, the bypass device 7a includes a movable contact piece 12 and an actuator 13 connected thereto. In this embodiment, the movement of the movable contact piece 12 is rotational. However, the movement of the movable contact piece 12 can also be translational or a combined movement. The actuator 13 is preferably an electromechanical actuator (e.g., a coil).

[0113] In this example, the fixed switch contact 14 is conductively connected to the terminal 10a, and the movable switch contact 15 is arranged on the movable contact piece 12 and conductively connected to the terminal 10b. The terminals 10a, 10b, the movable contact piece 12, the fixed switch contact 14, and the movable switch contact 15 are made of metal (preferably gold, copper, or a copper alloy).

[0114] In Figure 2 the position of the contact piece 12 shown, the fixed switch contact 14 and the movable switch contact 15 are open. Therefore, the two terminals 10a, 10b and the conductors ( Figure 2 and Figure 3 not shown in) mounted to the terminals 10a, 10b are electrically disconnected. If the contact piece 12 is moved to its lower position by the actuator 13, the fixed switch contact 14 and the movable switch contact 15 close and the terminals 10a, 10b and the conductors mounted to the terminals 10a, 10b are electrically connected.

[0115] Figure 3 The fan F for cooling the movable element (here the contact piece 12 with the movable switch contact 15) of the electromechanical bypass switch S1 is shown arranged in the (direct) vicinity of the electromechanical bypass switch S1.

[0116] In Figure 2 and Figure 3 the embodiment shown, the space in which the movable contact piece 12, the fixed switch contact 14, and the movable switch contact 15 are built in is a closed space. This space can be sealed by the bottom plate of the fan F or by a separate closing plate. In addition, depending on the situation, the space can be evacuated or filled with an inert gas. In this example, the cooling air sucked in by the fan F is blown out through the outlets 16a, 16b.

[0117] Figure 4 An alternative embodiment of the bypass device 7b is shown, which is very similar to the Figure 2 and Figure 3 bypass device 7a shown. In fact, Figure 2The arrangement shown is applicable to Figure 4 the bypass device 7b. Only the fan F is replaced by a heat exchanger 17 having two connectors 18a, 18b. The connector 18a can be an input for a gaseous or liquid heat carrier, while the connector 18b can be an output for said heat carrier. As is well known, the heat carrier is cooled in another heat exchanger ( Figure 4 not shown) so as to cool the movable contact piece 12. Furthermore, the space in which the movable contact piece 12, the fixed switch contact 14 and the movable switch contact 15 are built in is a closed space which, depending on the circumstances, can be evacuated or can be filled with an inert gas.

[0118] The cooling of the above type can be regarded as a kind of immersion cooling. Generally speaking, if a liquid heat carrier is used, the cooling power can be increased because liquids usually have a higher heat capacity than gases. Examples of the coolant are water, oil or electrically insulating liquids.

[0119] Instead of the fan F or the heat exchanger 17, a Peltier element can be used to cool the movable contact piece 12. Then the arrangement is basically the same as that Figure 4 shown, and the device denoted by the reference numeral "17" is a Peltier element. The connectors 18a, 18b become electrical connectors. Also, in this case, the space in which the movable contact piece 12, the fixed switch contact 14 and the movable switch contact 15 are built in is a closed space which can be evacuated or can be filled with an inert gas.

[0120] In the above examples, the bypass devices 7a, 7b are equipped with a closed space for the movable contact piece 12, the fixed switch contact 14 and the movable switch contact 15. This is beneficial but not a mandatory condition. In an Figure 5 alternative embodiment of the bypass device 7c shown, air blows through said space and thus over the movable contact piece 12. For this reason, the back plate of the base body 11 includes a groove 19 through which the air compressed by the fan F is blown out. In this case, the outlets 16a, 16b can be omitted.

[0121] Preferably, the air flow caused by the fan F is not only directed over the movable element of the electromechanical bypass switch S1 (here the contact piece 12 having the movable switch contact 15), but also over the fixed switch contact 14. In this way, the loss of burnt material can be blown away from the fixed switch contact 14 and the movable switch contact 15, thereby extending the service life of the electromechanical bypass switch S1. To improve this effect, it is also particularly advantageous to increase the air flow of the fan F by the cooling control CTC before the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1 are closed.

[0122] It should be noted that the air flow caused by the fan F can be concentrated on the contact piece 12 through a nozzle (not shown).

[0123] It should also be noted that the backpack fan F is not a prerequisite, and the fan F can also be installed far away from the electromechanical bypass switch S1. In one embodiment, a single fan F is provided for a plurality of electromechanical bypass switches S1. Such a fan F can even be arranged outside the hybrid circuit breaker 1. Then, the hybrid circuit breaker 1 can include a cooling connector for compressing air, such as a cooling connector for a duct leading to the fan F.

[0124] Furthermore, it should be noted that the bypass devices 7a..7c are not limited to a single cooling device F, 17, but a plurality of cooling devices F, 17 can be part of the bypass devices 7a..7c. For example, a first cooling device (e.g., a first fan F, a first heat exchanger 17 or a first Peltier element) can be arranged on the front side of the bypass devices 7a..7c, as Figure 3 and Figure 4 shown, and a second cooling device (e.g., a second fan F, a second heat exchanger 17 or a second Peltier element) can be arranged on the rear side of the bypass devices 7a..7c ( Figure 3 and Figure 4 not explicitly shown in). The types of the cooling devices F, 17 can even be mixed. For example, a fan F can be arranged on the front side of the bypass devices 7a..7c, while a heat exchanger 17 is arranged on the rear side thereof, and so on.

[0125] It should be noted that Figures 2 to 5 the bypass devices 7a..7c shown include only a single contact pair with a fixed switch contact 14 and a movable switch contact 15. Nevertheless, the bypass devices 7a..7c can also include a plurality of contact pairs, that is, having a plurality of fixed switch contacts 14 and a plurality of movable switch contacts 15. If the contact pairs are switched in series, a large total contact gap between the contact pairs can be achieved through a plurality of individual contact gaps. Therefore, with the same movement of the movable switch contact 15, a safe contact gap can be reached faster. If the contact pairs are switched in parallel, the bypass devices 7a..7c can conduct a higher current. Therefore, throughout the specification, generally a single contact pair can be exchanged with a plurality of contact pairs.

[0126] Now refer to Figure 6 explain Figure 1 the function of the arrangement shown. First, an embodiment without the electronic bypass switches S2a, S2b will be described, and then an embodiment with the electronic bypass switches S2a, S2b.

[0127] 1) Hybrid circuit breaker 1 without electronic bypass switches S2a, S2b:

[0128] Figure 6The first diagram shows the current Ia flowing through the input connectors 2a, 2b. The second diagram shows the current Ib flowing through the electromechanical bypass switch S1, the third diagram shows the third current Ic flowing through the semiconductor circuit 5, and the fourth diagram shows the current Id flowing through the rheostat R2. Figure 6 The fifth diagram in shows the (total) voltage U across the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1 at dedicated time points t0...t6.

[0129] During normal operation, the electromechanical bypass switch S1, switches S3, S4 and transistors T1, T2 are in the conducting state, thus connecting the input connector 2a and the output connector 3a and allowing current to flow through the current paths 4a, 4b (it should be noted that in this example there are no electronic bypass switches S2a, S2b). After the electromechanical bypass switch S1 conducts, it bypasses the transistors T1, T2 and the rectifiers D1..D4. It takes over the current from the transistors T1, T2 to reduce the forward voltage across the diodes D1...D4 and the transistors T1, T2, thereby reducing the power loss of the hybrid circuit breaker 1 during normal operation.

[0130] To further reduce the power loss of the hybrid circuit breaker 1 during normal operation, once the electromechanical bypass switch S1 conducts, the transistors T1, T2 can also be turned off.

[0131] Assume that an electrical fault 9 occurs at time point t0, such as a short circuit or an arc flash. Therefore, the first current Ia rises, as shown in Figure 6 the first diagram of. First, the entire current Ia flows through the electromechanical bypass switch S1 because its on-state resistance is very low, i.e., Ib = Ia. Therefore, the voltage U across the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1 rises slowly because it is only related to the resistance of the (copper) conductor at this time. At time point t1, the control unit CTRL detects the overcurrent situation by monitoring the voltage across the shunt resistor R3. Furthermore, the control unit CTRL sends an OPEN command to the electromechanical bypass switch S1. In addition, if the transistors T1, T2 are on during normal operation, the control unit CTRL will send a CLOSE command to them.

[0132] After a delay, the electromechanical bypass switch S1 starts to lift its movable switch contact 15 from the fixed switch contact 14 at time point t2, resulting in an arc burning between them. At time point t2, the currents Ia and Ib have increased to the current level I1, and the voltage U across the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1 has increased to the voltage level U1, typically <1V. The generated arc causes the voltage U to further increase to the voltage level U2, for example, about 12V for each pair of contacts (of course, the arc voltage depends on contact geometry, current density, material type, etc.). If the electromechanical bypass switch S1 includes two pairs of contacts, the (total) arc voltage is about 24V, and so on. This voltage level U2 is high enough to turn on the transistors T1, T2 and the rectifiers D1..D4 (it should be noted that the transistors T1, T2 were turned on shortly after time point t1 if they were off during normal operation).

[0133] Furthermore, the current Ib on the electromechanical bypass switch S1 commutates to the semiconductor circuit 5 from time point t2 to time point t3. Thus, as the current Ib on the electromechanical bypass switch S1 decreases, the current Ic on the semiconductor circuit 5 increases in the same way. It should be noted at this time that only a few microseconds are required from time point t2 to time point t3.

[0134] At time point t3, this transfer is completed, and the semiconductor circuit 5 carries the full current Ia, i.e., Ic = Ia. During commutation, the current Ia flowing through the input connectors 2a, 2b rises to the current level I2. The voltage U across the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1 now drops to the forward voltage of the transistors T1, T2 and the rectifiers D1...D4. However, the current Ic will still increase while the transistors T1, T2 are still in the on state.

[0135] At time point t4, the transistors T1, T2 are finally turned off, causing the current Ic flowing through the semiconductor circuit 5 to drop to zero. As a result, the current commutates to the buffer circuit R1, C, D5 and the varistor R2, i.e., Id = Ia. In particular, t4 < 450μs.

[0136] Up to time point t5, the voltage U across the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1 rises to the peak voltage U4, which depends on the voltage across the rheostat R2. For example, the peak voltage U4 is in the range of 1000V at a rheostat voltage of 380VDC or in the range of 1600V at a rheostat voltage of 700VDC. The current Ia at the input connectors 2a, 2b decreases until it becomes zero at time point t6. Shortly before time point t6, the voltage U across the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1 drops to the voltage level U3, which corresponds to the line voltage, i.e., the voltage of the voltage source VP.

[0137] It should be noted that the transistors T1, T2 may not be turned off until the air gap between the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1 is large enough and the air ionization state between the contacts is low enough to carry the peak voltage U4 without the risk of reigniting the arc between the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1. In other words, the dielectric strength between the fixed switch contact 14 and the movable switch contact 15 should be large enough before the transistors T1, T2 are turned off.

[0138] Therefore, not only the commutation time (t3 - t2) but also the time required to have a large enough dielectric strength between the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1 affects the current level I3. In the above example, this condition is reached at time point t4 or a time point before it (it should be noted that the arc voltage for each contact pair is about 12V).

[0139] It should also be noted that in Figure 6 the fifth figure, the alternation of the line voltage is not visible because the time span between t0 - t6 is very short, specifically in the range of 1ms. Therefore, the time span between t0 - t6 is short in terms of the voltage period of the voltage source VP at a typical frequency of 50Hz or 60Hz, i.e., 20ms or 16.6ms. Therefore, the line voltage is quasi-constant during the time span between t0 - t6.

[0140] If the line voltage is an alternating voltage or if a bidirectional current is to be provided for a DC line voltage, the hybrid circuit breaker 1 must be ready to accept a bidirectional current. For this reason, the rectifiers D1..D4 supply a rectified voltage to the transistors T1, T2. Alternatively, the transistors T1, T2 can also be switched in the opposite direction. For this reason, and because of the body diodes of the MOSFETs used for the electronic bypass switches S2a, S2b in this example, they are switched in anti-series. Alternatively, if bidirectional current is allowed, a single device can be used instead of the anti-series electronic bypass switches S2a, S2b.

[0141] The switches S3, S4 have no special function in the case of overcurrent. They are added to the hybrid circuit breaker 1 to provide current isolation. They have a large contact distance (>3 mm), but do not need to switch very quickly. Nevertheless, they can also be opened by the control unit CTRL in the event of an electrical fault 9. If so, the switches S3, S4 are preferably opened when the current Id is zero or almost zero. Thus, the switches S3, S4 open shortly after or before the time point t6.

[0142] As Figure 6 shown in the second figure of

[0143] it is surprising that if only the electromechanical bypass switch S1 is cooled, the electrical stress on the semiconductor circuit 5 and the temperature of the semiconductor circuit 5 can also be kept low. The reason for this surprising effect is the movable element of the electromechanical bypass switch S1 (see Figure 2 the contact piece 12 with the movable switch contact 15 in

[0144] From Figure 6 it can be clearly seen that the commutation time (t3 - t2) and even the safety gap time (≈t4) of the electromechanical bypass switch S1 significantly affect the level of the current I, the electromechanical bypass switch S1 must carry the current level I in the event of a fault, and the transistors T1, T2 and other components (such as cables, fuses, etc.) must carry the current level I in the event of a fault.

[0145] By specifically reducing the safety air gap time (≈t4), the electrical energy forced into the semiconductor circuit 5 and converted into heat energy there can be significantly reduced. It is also particularly advantageous that the power diverted away from the semiconductor circuit 5 by the faster electromechanical bypass switch S1 is much higher than the power of the cooling devices F, 17. In other words, the lever effect between cooling the electromechanical bypass switch S1 and the multiplication effect on the semiconductor circuit 5 is utilized. For such a large effect, only small cooling devices F, 17 with low power are required.

[0146] For the same effect, cooling the semiconductor circuit 5 without cooling the electromechanical bypass switch S1 would require a much higher cooling power, a much larger cooling device, and would be much more complex. Since the time during which the semiconductor circuit 5 effectively conducts current is short, the cooling of the semiconductor circuit 5 must occur near the junctions of the semiconductor elements of the semiconductor circuit 5 to be effective. In fact, the duration of this time span t2 - t4 is only a few hundred microseconds.

[0147] However, by using the cooling devices F, 17, the semiconductor circuit 5 can be made relatively small without any further cooling. Furthermore, since the semiconductor circuit 5 occupies a significant share in the size (i.e., volume) of the semiconductor circuit 5 and also in the cost of the hybrid circuit breaker 1, the hybrid circuit breaker 1 itself can be made smaller and cheaper than in the prior art.

[0148] The count of the varistor R2 and the buffer circuit 6 including the buffer resistor R1, buffer capacitor C, and buffer diode D5 is exactly the same. The longer the time required to reach the safety air gap, the greater the current and energy that the varistor R2 and the buffer circuit 6 must withstand. Therefore, the sizes of the varistor R2 and the buffer circuit 6 also increase significantly with the time to reach the safety air gap.

[0149] However, the sizes of the semiconductor circuit 5 and the varistor R2 are not only related to cost. In addition, the reduction in the size of the semiconductor circuit 5 has a positive impact on the loop inductance of the hybrid circuit breaker 1, and thus reduces the commutation time (t3 - t2) of the fault current from the electromechanical bypass switch S1 to the semiconductor circuit 5. The following explains this effect by using Figure 7 to explain this effect.

[0150] Figure 7 shows for the first embodiment Figure 1 The simplified equivalent circuit of the tripping part of the hybrid circuit breaker 1 shown, without the electronic bypass switches S2a, S2b, but with switching arcs. Specifically, Figure 7Shows a first voltage source VT1 for the first transistor T1, a second voltage source VT2 for the second transistor T2, two additional voltage sources VD1 and VD2 for the diodes D1 and D2 of the rectifier, and finally, a voltage source Varc for the arcing between the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1. There are inductors L0..L5 between the voltage sources VT1, VT2, VD1, VD2, and Varc, and LT1, LT2 representing the inductance of the line between the first transistor T1 and the second transistor T2, the diodes D1 and D2 of the rectifier, and the electromechanical bypass switch S1. Finally, Figure 7 Shows the currents Ia, Ib, and Ic. The following formula shows the relationship between the above parameters.

[0151] Ia = Ib + Ic

[0152] V semi = VD1 + VD2 + VT

[0153]

[0154]

[0155] Therefore, based on the above formula, it can be understood that the loop inductance L loop has a significant effect on the commutation time t comm (t3 - t2). Smaller semiconductors also have lower internal resistance, thus reducing the voltage V of the semiconductor circuit 5 semi .

[0156] In summary, cooling (only) the electromechanical bypass switch S1 with the cooling devices F, 17 can especially:

[0157] - Reduce the loop inductance L loop ,

[0158] - Lower the (forward) voltage V of the semiconductor circuit 5 semi , and

[0159] - Based on the above effects, reduce the commutation time t comm (t3 - t2)

[0160] - And lower the current level I2,

[0161] - Shorten the time (t4 - t2) to achieve a gas gap saving between the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1,

[0162] - Based on the above effects, lower the current level I3,

[0163] - Reduce the energy forced into the semiconductor circuit 5 and

[0164] - Reduce the thermal stress and electrical stress on the semiconductor circuit 5.

[0165] The reduced current commutation time t comm (t3 - t2) also means that the switching arc has less adverse effect on the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1. In other words, the proposed measures allow for higher currents without shortening the service life of the hybrid circuit breaker 1.

[0166] Therefore, the cooling devices F, 17 have multiple effects on the energy forced into the semiconductor circuit 5.

[0167] 2) Hybrid circuit breaker 1 with electronic bypass switches S2a, S2b:

[0168] This hybrid circuit breaker 1 behaves similarly to one of the hybrid circuit breakers 1 in the first embodiment, but not exactly the same.

[0169] During normal operation, the electromechanical bypass switch S1, switches S3, S4, additional electronic bypass switches S2a, S2b, and (optionally) transistors T1, T2 are in the conducting state, thus connecting the input connector 2a and the output connector 3a and allowing current to flow through the current paths 4a, 4b. It should be noted that the electronic bypass switches S2a, S2b with extremely low on-state resistance are used to reduce the power loss of the hybrid circuit breaker 1 during normal operation.

[0170] Again, assume that an electrical fault 9 occurs at time point t0 and, as a result, the first current Ia rises again, as Figure 6 depicted in the first figure of

[0171] At time point t1, the control unit CTRL detects the overcurrent situation by monitoring the voltage across the shunt resistor R3, and then sends an OPEN command to the electromechanical bypass switch S1 and the electronic bypass switches S2a, S2b. In addition, if the transistors T1, T2 are open during normal operation, the control unit CTRL sends a CLOSE command to them.

[0172] After a short delay but faster than the electromechanical bypass switch S1, the electronic bypass switches S2a, S2b cut off the current on the current path 4a. Then, the electromechanical bypass switch S1 starts to lift its movable switch contact 15 from the fixed switch contact 14 at time point t2. Since the electronic bypass switches S2a, S2b are already open, there is no burning switch arc between the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1 now.

[0173] Therefore, transistors T1 and T2 may not be turned off at this time because the electronic bypass switches S2a and S2b may be damaged by the peak voltage U4. The reason is that the electronic bypass switches S2a and S2b with extremely low on-resistance have extremely low breakdown voltages, for example, in the range of 30V, while the peak voltage U4 rises to several hundred or even 1000V. Therefore, transistors T1 and T2 may not be turned off until the air gap between the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1 is large enough to carry the peak voltage U4 without risking arcing between the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1 and arc combustion therebetween. In this case, the voltage between the fixed switch contact 14 and the movable switch contact 15 will drop to the arc voltage (about 12V), causing the voltage on the electronic bypass switches S2a and S2b to rise to close to the peak voltage U4, which will undoubtedly damage the electronic bypass switches S2a and S2b. Therefore, again, the full opening time t4 - t2 of the electromechanical bypass switch S1 is essential for the current level I3 that the semiconductor circuit 5 must withstand.

[0174] Therefore, the electronic bypass switches S2a and S2b have a positive effect. Since the current Ib has commutated to the semiconductor circuit 5 before the movable switch contact 15 of the electromechanical bypass switch S1 moves (i.e., the contact piece 12 has not moved), there is no arc combustion between the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1. Therefore, the service life of the electromechanical bypass switch S1 is extended. The fixed switch contact 14 and the movable switch contact 15 can also be more optimized in terms of their resistance and must be worse in terms of thermal stability.

[0175] In addition, the safe air gap between the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1 is reached faster. The reason is that there is no arc plasma between the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1, and the isolation ability of the air gap is reduced due to the absence of a switching arc. In other words, the electronic bypass switches S2a and S2b shorten the full disconnection time t4 - t2 of the electromechanical bypass switch S1 because the movable switch contact 15 does not need to move as far. However, the semiconductor circuit 5 should not cut off the current unless the air gap between the fixed switch contact 14 and the movable switch contact 15 is large enough to withstand the peak voltage U4 caused by the semiconductor circuit 5 without risking flashover between the fixed switch contact 14 and the movable switch contact 15, because such flashovers can cause avalanche breakdown of the electronic bypass switches S2a and S2b.

[0176] Therefore, by using the electronic bypass switches S2a, S2b, the load on the electromechanical bypass switch S1 and the semiconductor circuit 5 can be reduced. In this case, compared to the case of the hybrid circuit breaker 1 without the electronic bypass switches S2a, S2b, the current Ia is commutated to a lower current level of the semiconductor circuit 5.

[0177] Despite the above disclosure, it should be noted that the electronic bypass switches S2a, S2b are optional for the disclosed hybrid circuit breaker 1 and can be omitted.

[0178] All embodiments

[0179] If the electromechanical bypass switch S1 is a multi-contact pair switch, it is advantageous for all embodiments. In particular, the electromechanical bypass switch S1 can include two pairs of contacts, namely two pairs of fixed switch contacts 14 and movable switch contacts 15. However, Figure 1 the electromechanical bypass switch S1 can have a different number of contact pairs. For example, it can include only one contact pair (as Figures 2 to 5 shown) or even more than two contact pairs. By using multiple contact pairs, multiple arcs with multiple arc voltages V arc are generated simultaneously or almost simultaneously, which reduces the commutation time (t3 - t2).

[0180] In all embodiments, the thermal coupling between the cooling devices F, 17 and the electromechanical bypass switch 1 is higher than the thermal coupling between the cooling devices F, 17 and the semiconductor circuit 5. This does not necessarily mean that the semiconductor circuit 5 is not cooled by the cooling devices F, 17 at all, but the cooling is concentrated on the electromechanical bypass switch 1. It should also be noted that the basic purpose is not to cool a large number of switch arcs (if any), but to cool the current-carrying metal elements of the electromechanical bypass switch 1. Cooling of the switch arcs may occur, but this is only a side effect.

[0181] The electromechanical bypass switch 1 can in particular be implemented as a "high-speed" electromechanical bypass switch with a switching time (time span t1 - t4) ≤ 400 μs. After said switching time, the gap between the fixed switch contact 14 and the movable switch contact 15 is large enough to withstand the peak voltage U4. This condition is met for U4 = 1000 V with a total contact gap of 1.2 mm in the first embodiment (hybrid circuit breaker 1 without electronic bypass switches S2a, S2b), and a total contact gap of 0.15 mm in the second embodiment (hybrid circuit breaker 1 with electronic bypass switches S2a, S2b). The reason for the different gap values is that the ionized air in the contact gap in the first embodiment is more conductive due to the switching arc than the "cold" air in the second embodiment (remember that there is no switching arc in the second embodiment). In a more preferred embodiment, the switching time (time span t1 - t4) is even ≤ 400 μs. In particular, if the "high-speed" electromechanical bypass switch S1 is used in the hybrid circuit breaker 1, cooling of the semiconductor circuit 5 can be omitted. In other words, the thermal coupling between the effective cooling devices F, 17 and the semiconductor circuit 5 can be < 0.01 times the thermal coupling between the effective cooling devices F, 17 and the electromechanical bypass switch S1. It should be noted that the contact gap mentioned above refers to the total gap, which is twice the (single) contact gap in the case of a double contact pair.

[0182] Especially for the above reasons, it is advantageous for the cooling devices F, 17 to be able to:

[0183] - generate a heat flow when the electromechanical bypass switch S1 is closed and / or during > 90% of the operating time of the hybrid circuit breaker 1, or

[0184] - generate a cooling fluid flow when the electromechanical bypass switch S1 is closed and / or during > 90% of the operating time of the hybrid circuit breaker 1.

[0185] Furthermore, it is advantageous for the cooling devices F, 17 to be in their on state when:

[0186] - within at least the current range from 90% to 100% of the tripping current of the hybrid circuit breaker 1, or

[0187] - within at least the current range from the rated current of the hybrid circuit breaker 1 to the tripping current of the hybrid circuit breaker 1.

[0188] The above ranges may or may not include the tripping current.

[0189] In a simple and robust embodiment, the cooling devices F, 17 are simply connected to a power source and operate continuously.

[0190] However, when the electromechanical bypass S1 switch is closed and / or during the operation time of the hybrid breaker 1 > 90%, the cooling control CTC can be operably connected to the cooling devices F, 17 to cool the electromechanical bypass S11. In other words, when the electromechanical bypass switch S1 is closed and / or during the operation time of the hybrid breaker > 90%, the cooling devices F, 17 are in their on state or on.

[0191] The cooling control CTC can also be ready to open on the effective cooling devices F, 17 at least within a current range of 90% to 100% of the trip current of the hybrid breaker 1 or at least within a current range from the rated current of the hybrid breaker 1 to the trip current of the hybrid breaker 1. The above ranges may or may not include the trip current.

[0192] In these ways, the electromechanical bypass switch S1 remains in good condition to cope with possible switching or tripping events.

[0193] As described above, advantageously, the air flow caused by the fan F is not only directed onto the contact piece 12 and the movable switch contact 15, but also onto the fixed switch contact 14. In this way, the loss of burned material can be blown away from the fixed switch contact 14 and the movable switch contact 15, thereby extending the service life of the electromechanical bypass switch S1. To improve this effect, it is also particularly advantageous if the cooling control CTC increases the air flow of the fan F before the fixed switch contact 14 and the movable switch contact 15 of the electromechanical bypass switch S1 are closed. It should also be noted that the fan F does not need to stop during a switching arc event, but it can also (but not only) operate when a switching arc occurs.

[0194] Again, it should be noted that the present invention does not focus on cooling the switching arc, but on cooling the movable elements 12, 15 of the electromechanical bypass switch S1. Generally, the cooling power of the proposed cooling devices F, 17 is too low to sufficiently cool the switching arc. The power of the switching arc is around several hundred watts, while the cooling power is around several watts. Generally, the temperature of the switching arc is reduced by < 5°C. If the space in which the movable contact piece 12, the fixed switch contact 14 and the movable switch contact 15 are placed is an enclosed space, it is simply impossible to cool the switching arc.

[0195] By applying the disclosed features, various hybrid breakers of one type of series or group of hybrid breakers 1 with different rated current capacities can be provided. In particular, the hybrid breakers 1 with different rated current capacities can include the same type of electromechanical bypass switch S1 and / or the same type of semiconductor circuit 5.

[0196] For example, a first hybrid circuit breaker 1 having a first rated current capacity and / or a first current-time characteristic may include cooling devices F, 17, while a second hybrid circuit breaker 1 having a second rated current capacity lower than the first rated current capacity and / or a second current-time characteristic less robust than the first current-time characteristic does not include cooling devices F, 17, although the mechanical bypass switch S1 and / or the semiconductor circuit 5 may be of the same type for both hybrid circuit breakers 1.

[0197] Generally, when the current Ib on the electromechanical bypass switch S1 measured by the shunt R3 increases and / or when the current-time characteristic would change to a more robust characteristic, the cooling power Pc of the effective cooling devices F, 17 can be increased by the cooling control CTC. In this way, the cooling power adapts to the changing requirements, and the electromechanical bypass switch S1 remains in good condition for the turn-off event.

[0198] In the above context, Figure 8 The typical current-time characteristic or tripping characteristic of the hybrid circuit breaker 1 is shown. Specifically, the variation of the tripping time t with the ratio I / Inom of the current I divided by the rated current is shown for type "B" circuit breakers (standard), type "C" circuit breakers (elevated inrush current), and type "D" circuit breakers (high capacitive or inductive loads). As indicated by the arrow, the higher the cooling power Pc, the more robust the tripping characteristic of the hybrid circuit breaker 1, or the higher the current I or Ib.

[0199] In one embodiment, one and the same hybrid circuit breaker 1 provides multiple current-time characteristics or tripping characteristics, which can be selected during the setup process. For example, one of the type "B", type "C", or type "D" characteristics can be selected. Thus, when there is a transition from type "B" to type "C" or from type "C" to type "D", the cooling power can be increased, and vice versa.

[0200] In another embodiment, different current-time characteristics are provided by different hybrid circuit breakers 1, where there are electromechanical bypass switches S1 of the same type and / or semiconductor circuits 5 of the same type and different types of cooling devices F, 17 or the same type of cooling devices F, 17 operating at different power levels Pc.

[0201] Generally, the cooling power Pc can vary continuously or stepwise. Preferably, the cooling power Pc varies continuously according to the current Ib on the electromechanical bypass switch S1 and / or varies stepwise according to different current-time characteristics.

[0202] For the reasons given above, one and the same mechanical bypass switch S1 and / or one and the same semiconductor circuit 5 can carry a much higher current Ia, simply because a small cooling device F, 17 is attached to the mechanical bypass switch S1 of the first hybrid circuit breaker 1. In addition, the housings of hybrid circuit breakers 1 with different rated currents can have the same external dimensions.

[0203] In this way, it is much easier and cheaper to provide a type of series or group of hybrid circuit breakers 1 than in the prior art, because only a small number of different components are required for a variety of rated currents Ia.

[0204] The various hybrid circuit breakers 1 of the series or group of the type described may include different types of cooling devices F, 17 or the same type of cooling devices F, 17.

[0205] By the proposed measures, the hybrid circuit breaker 1, in particular the semiconductor circuit 5, can withstand higher currents than in the prior art without increasing its size and cost. Thus, the hybrid circuit breaker 1 for high rated currents can be made smaller and cheaper than before. The leverage effect between cooling the electromechanical bypass switch S1 and the multiplication effect on the semiconductor circuit 5 is utilized. Only low cooling power is required, so only small cooling devices F, 17 are needed to achieve a large effect. For the same effect, cooling the semiconductor circuit 5 without cooling the electromechanical bypass switch S1 would require much higher cooling power and much larger cooling devices.

[0206] It should be noted in this regard that in the prior art, doubling the rated current means quadrupling the electrical energy, and thus quadrupling the size and cost of the semiconductor circuit 5 and serious problems with the rheostat R2. By using the cooling devices F, 17, this rule can be broken.

[0207] Advantageously,

[0208]

[0209] where A is the effective chip area of the semiconductor circuit 5 in cm 2 , n is the number of power switching elements (such as diodes, transistors, thyristors, etc.) in the semiconductor circuit 5, I cu is the short-circuit current switching capacity of the hybrid circuit 1 breaker in amperes, and di is the current density of a single power switching element in A / cm 2 . In Figure 1 the case of, the semiconductor circuit 5 includes five non-controlled power switching elements D1...D5 and one controlled power switching element, which is implemented by two parallel thyristors T1, T2. For a typical current density di = 150 A / cm 2 and a typical short-circuit current switching capacity I cu= 20 kA, which particularly means:

[0210]

[0211] A < 200.0 cm 2

[0212] Furthermore, it is advantageous that

[0213]

[0214] where V is the volume of the rheostat R2 that is switched in parallel with the electromechanical bypass switch 1, in cm 3 , I cu is the short-circuit current switching capacity of the hybrid circuit breaker 1, in amperes, and dE is the energy density of the rheostat R2, in J / cm 3 , where the energy density dE refers to the effective volume of the rheostat R2. For a typical energy density dE of a metal oxide material = 250 J / cm 3 and a typical short-circuit current switching capacity I cu = 20 kA, which particularly means:

[0215]

[0216] V < 2.03 cm 3

[0217] It should also be noted that the term "comprising" does not exclude other elements, and the use of the article "a" or "an" does not exclude a plurality. Elements described in connection with different embodiments can also be combined. It should also be noted that the reference signs in the claims should not be construed as limiting the scope of the claims.

[0218] List of reference signs

[0219] 1 Hybrid circuit breaker

[0220] 2a, 2b Input connectors

[0221] 3a, 3b Output connectors

[0222] 4a, 4b Current paths

[0223] 5 Semiconductor circuit

[0224] 6 Buffer circuit

[0225] 7, 7a..7c Bypass devices

[0226] 8 Load

[0227] 9 Electrical fault

[0228] 10a, 10b Terminals

[0229] 11 Substrate

[0230] 12 Movable contact piece

[0231] 13 Actuator

[0232] 14 Fixed switch contact

[0233] 15 Movable switch contact

[0234] 16a, 16b Outlet

[0235] 17 Heat exchanger

[0236] 18a, 18b Connector

[0237] 19 Groove

[0238] C Buffer capacitor

[0239] CTC Cooling control

[0240] CTRL Control unit

[0241] D1..D4 Rectifier

[0242] D5 Buffer diode

[0243] F Fan

[0244] I1..I3 Current level

[0245] Ia..Id Current

[0246] Inom Rated current

[0247] L Grid inductance

[0248] L0..L5 Line inductance

[0249] Pc Cooling power

[0250] LT1, LT2 Inductance of transistors T1 and T2

[0251] R1 Buffer resistor

[0252] R2 Rheostat

[0253] R3 Shunt

[0254] R4 Grid resistance

[0255] S1 Electromechanical bypass switch

[0256] S2a, S2b Electronic bypass switch (MOSFET)

[0257] t time

[0258] t0..t6 time points

[0259] T1, T2 transistors (IGBTs)

[0260] U voltage

[0261] U1..U4 voltage levels

[0262] VP voltage source

[0263] Varc voltage source of the arc in the electromechanical bypass switch S1

[0264] VD1, VD2 voltage sources of the rectifier diodes D1 and D2

[0265] VT1 voltage source of the first transistor T1

[0266] VT2 voltage source of the second transistor T2

Claims

1. A hybrid circuit breaker (1), comprising input connectors (2a, 2b) that receive electrical energy from an electrical grid, output connectors (3a, 3b) that transmit electrical energy to a load (8), current paths (4a, 4b), each current path (4a, 4b) connecting an input connector (2a, 2b) and an output connector (3a, 3b), an electromechanical bypass switch (S1) in at least one of the current paths (4a, 4b), a semiconductor circuit (5) connected in parallel with the electromechanical bypass switch (S1), and Control unit (CTRL), the control unit (CTRL) being capable of controlling, in the case of a switching operation, the commutation from the current paths (4a, 4b) in which the electromechanical bypass switch (S1) is arranged to the semiconductor circuit (5), characterized in that, the circuit breaker (1) further comprises: an effective cooling device (F, 17) located near the electromechanical bypass switch (S1), the effective cooling device being configured to cool movable elements (12, 15) of the electromechanical bypass switch (S1); and where A is the effective chip area of the semiconductor circuit (5) in cm 2 , n is the number of power switching elements in the semiconductor circuit (5), I cu is the short-circuit current switching capacity of the hybrid circuit breaker (1) in amperes, and di is the current density of a single power switching element in A / cm 2 .

2. The hybrid circuit breaker (1) according to claim 1, characterized in that, the cooling device (F) is implemented as a fan, and the fan is placed directly near a fixed switch contact (14) and a movable switch contact (15) of the electromechanical bypass switch (S1).

3. The hybrid circuit breaker (1) according to claim 1, characterized in that, The cooling device (F) is implemented as a fan, and the hybrid circuit breaker (1) comprises an air duct for guiding an air flow caused by the fan (F) over a fixed switch contact (14) and a movable switch contact (15) of the electromechanical bypass switch (S1).

4. The hybrid circuit breaker (1) according to claim 1, characterized in that, A varistor (R2) is switched in parallel with the electromechanical bypass switch (S1), and wherein Where V is the volume of the rheostat (R2), in cm 3 , I cu is the short-circuit current switching capacity of the hybrid circuit breaker (1), in amperes, dE is the energy density of the rheostat (R2), in J / cm 3 , where the energy density dE refers to the effective volume of the rheostat (R2); and, where the [HA] is the unit of "2.54•10 -2 " and it represents [Henry • Ampere].

5. A method of operating a hybrid circuit breaker (1), comprising input connectors (2a, 2b) that receive electrical energy from an electrical grid, output connectors (3a, 3b) that transmit electrical energy to a load (8), current paths (4a, 4b), each current path (4a, 4b) connecting an input connector (2a, 2b) and an output connector (3a, 3b), an electromechanical bypass switch (S1) in at least one of the current paths (4a, 4b), a semiconductor circuit (5) connected in parallel with the electromechanical bypass switch (S1), and a control unit (CTRL) that is capable of controlling, in the case of a switching operation, a commutation from a current path (4a, 4b) in which the electromechanical bypass switch (S1) is arranged to the semiconductor circuit (5), characterized in that movable elements (12, 15) of the electromechanical bypass switch (S1) are effectively cooled by an effective cooling device (F, 17) arranged near the electromechanical bypass switch (S1); and Where A is the effective chip area of the semiconductor circuit (5), in cm 2 , n is the number of power switching elements in the semiconductor circuit (5), I cu is the short-circuit current switching capacity of the hybrid circuit breaker (1), in amperes, and di is the current density of a single power switching element, in A / cm 2 .

6. The method according to claim 5, characterized in that a thermal coupling between the cooling device (F, 17) and the electromechanical bypass switch (S1) is higher than a thermal coupling between the cooling device (F, 17) and the semiconductor circuit (5).

7. The method according to claim 5 or 6, characterized in that, When the electromechanical bypass switch (S1) is closed, the effective cooling device (F, 17) of the hybrid circuit breaker (1) is in its on state.

8. The method according to claim 5, wherein During an operation time of the hybrid circuit breaker (1) > 90%, the active cooling device (F, 17) is in its switched-on state.

9. The method according to claim 5, characterized in that, When the electromechanical bypass switch (S1) is closed and / or during an operation time of the hybrid circuit breaker (1) > 90%, the active cooling device (F, 17) generates a cooling fluid flow.

10. The method according to claim 5, characterized in that The active cooling device (F, 17) is in its switched-on state at least in a current range from 90% to 100% of the tripping current of the hybrid circuit breaker (1).

11. The method according to claim 5, characterized in that The active cooling device (F, 17) is in its switched-on state at least in a current range from the rated current of the hybrid circuit breaker (1) to the tripping current of the hybrid circuit breaker (1).

12. The method according to claim 5, wherein When the current (Ib) on the electromechanical bypass switch (S1) increases and / or when the current-time characteristic changes to a more robust characteristic, the cooling power (Pc) of the active cooling device (F, 17) increases.

13. The method according to claim 5, characterized in that, Before the electromechanical bypass switch (S1) is closed, the air flow of the active cooling device (F) implemented as a fan is increased.

14. The method according to claim 5, wherein The time span between the time point (t0) of an electrical fault (9) occurring and the time point (t4) at which the current (Ic) flowing through the semiconductor circuit (5) drops to zero is < 450 µs.

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