Furnace power supply device with cooling system

Abstract

The invention relates to a furnace power supply device (20) for supplying an electric furnace with electrical energy, the furnace power supply device (20) being connectable to a three-phase electrical network (10) and to at least one electrode (30) of the electric furnace, the furnace power supply device (20) comprising at least one power module (100), wherein the power module (100) comprises a rectifier stage (110) connectable to the three-phase electrical network (10) and a converter stage (120) connectable to at least one electrode (30) of the electric furnace, where the furnace power supply (20) comprises at least one DC bus (130), where the DC bus (130) connects the rectifier stage (110) of at least one power module (100) to the converter stage (120), where the furnace power supply (20) comprises a cooling system (140).

Description

[0001] This invention relates to a furnace power supply device with a cooling system, a furnace, and a production line.

[0002] Metals, especially steel and metallic ores, are typically melted and heated in electric furnaces by an electric arc. These furnaces, particularly electric arc furnaces, electric reduction furnaces, submerged arc resistance furnaces, ladle furnaces, or open bath furnaces, operate with direct current (DC), alternating current (AC), or multiphase AC. Typically, at least one electrode is used for this purpose, extending through the furnace top into the furnace vessel, while other electrodes are provided corresponding to the first electrode or arranged at the bottom of the melting vessel.

[0003] Electric arc furnaces are typically operated using dedicated power supply systems to both supply the required amount of electrical energy and mitigate the highly nonlinear load on the power grid during operation. Consequently, these power supply systems generate significant heat losses during furnace operation, leading to increased cooling requirements.

[0004] This invention addresses this problem by providing a furnace power supply device with improved cooling capabilities.

[0005] The problem behind this invention is solved by the apparatus according to claim 1. Advantageous embodiments are described in the dependent tasks.

[0006] In particular, the problem behind the present invention is solved by a furnace power supply device for supplying electrical energy to an electric furnace, wherein the furnace power supply device is capable of being connected to a three-phase power grid and at least one electrode of the electric furnace, wherein the furnace power supply device includes at least one power module, wherein the power module includes a rectifier stage capable of being connected to the three-phase power grid and a converter stage capable of being connected to at least one electrode of the electric furnace, wherein the furnace power supply device includes at least one DC bus, wherein the DC bus connects the rectifier stage of at least one power module to the converter stage, and wherein the furnace power supply device includes a cooling system.

[0007] In the following text, the term "intended use of furnace power supply unit" is used to describe the purpose of the furnace power supply unit in supplying electrical energy to the electric furnace during operation.

[0008] The advantage of a furnace power supply unit designed in this way lies in its improved cooling capacity. In the intended use of a furnace power supply unit, significant heat loss occurs. The cooling system of the furnace power supply unit can efficiently absorb this heat loss.

[0009] A three-phase power grid is a multiphase system used for power generation, transmission, and distribution. A three-phase power grid provides alternating current (AC), specifically, three AC currents, each of which has a +120-degree phase difference with one of the other two AC currents and a -120-degree phase difference with the corresponding other AC current.

[0010] A three-phase power grid can be a high-voltage three-phase power grid, a medium-voltage three-phase power grid, or a low-voltage three-phase power grid.

[0011] The high voltage can be greater than or equal to 36 kV, preferably greater than or equal to 60 kV, and particularly preferably greater than or equal to 100 kV. More advantageously, the high voltage can be greater than or equal to 150 kV, preferably greater than or equal to 200 kV, and particularly preferably greater than or equal to 300 kV. More advantageously, the high voltage can be greater than or equal to 400 kV, preferably greater than or equal to 700 kV, and particularly preferably greater than or equal to 1100 kV.

[0012] The medium voltage can be less than or equal to 36 kV. More advantageously, the medium voltage can be less than or equal to 30 kV, preferably less than or equal to 20 kV, and particularly preferably less than or equal to 15 kV.

[0013] The medium voltage can be greater than or equal to 1 kV, preferably greater than or equal to 2 kV, and particularly preferably greater than or equal to 10 kV. More advantageously, the medium voltage can be greater than or equal to 15 kV, preferably greater than or equal to 20 kV, and particularly preferably greater than or equal to 30 kV.

[0014] The low voltage can be greater than or equal to 50V, preferably greater than or equal to 60V, and particularly preferably greater than or equal to 100V. More advantageously, the low voltage can be greater than or equal to 120V, preferably greater than or equal to 220V, and particularly preferably greater than or equal to 240V.

[0015] The low voltage can be less than or equal to 1,000V, and particularly preferably less than or equal to 900V. More advantageously, the low voltage can be less than or equal to 600V, preferably less than or equal to 240V, and particularly preferably less than or equal to 220V.

[0016] Preferably, the voltage level can be defined according to IEC 60038. Particularly preferably, the voltage level can be defined according to Tables 1, 3 and 4 of IEC 60038.

[0017] The electric furnace can be an electric arc furnace, an electric reduction furnace, a submerged arc resistance furnace, and / or any other electric furnace suitable for melting metal or non-metal materials.

[0018] An electrode is an electrical conductor used to make contact with a part of a circuit, specifically an electric furnace, particularly the non-metallic part of the circuit. The non-metallic part of the circuit may correspond to the atmosphere in the electric furnace.

[0019] The electrodes can be made of high-density graphite and / or tungsten. The electrodes can be designed to transfer electrical energy, thereby forming an electric arc between their tips and the furnace charge material. The electrodes can be prebaked electrodes or self-baking electrodes (Soederberg electrodes) and / or extruded / composite electrodes, which are combinations of Soederberg electrodes with a prebaked electrode and / or hollow electrode system as a core. This allows for the filling of fine powder (prebaked, self-baking) through a central hole. Thus, the choice of electrode type can depend on: electrode size, material / metallurgical and economic aspects of production (such as operating costs).

[0020] The electrodes of the electric furnace can be located at the top of the furnace. Preferably, the top-located electrodes are connected to a height adjustment member, thereby allowing the distance between the electrodes and the specified metal material and / or specified molten metal material in the furnace to be varied. This variation can be controlled and / or adjusted by an electrode adjuster.

[0021] The second electrode can be placed in the furnace container of the electric furnace, or it can be the inner wall of the furnace container, specifically the bottom wall component.

[0022] The second electrode can also be arranged on the top of the electric furnace, and preferably it can also be connected to the height adjustment component.

[0023] The electric furnace can also have three, four, or more electrodes. Each electrode can be connected to a height adjustment component.

[0024] Electric furnaces can be operated using direct current (DC) or alternating current (AC).

[0025] In an electric furnace operated by direct current, the electrodes may be referred to as anodes and cathodes. The cathode may be arranged at the top of the furnace. The anode may be divided into several segments. The anode, preferably the bottom electrode, comprises metal and / or conductive material at the bottom of the furnace, and an electric arc is formed from the top between the furnace charge material and the cathode, preferably a cathode made of graphite, carbon, or tungsten.

[0026] The power module is suitable for or configured to supply electrical energy to the electric furnace, specifically, to supply electrical energy from a three-phase power grid. Preferably, the power module is suitable for or configured to supply the electric furnace with a current of appropriate current intensity and / or current strength, an appropriate voltage level, and / or a voltage of appropriate frequency.

[0027] The power module may include a power module housing that at least partially limits the volume of the power module housing. The power module housing may include or may be one or more cabinets, specifically a switch cabinet.

[0028] In the context of this invention, the housing is designed to protect components arranged within the housing volume from external influences, particularly mechanical and / or electrical influences, and to provide defined air conditions within the housing volume, specifically defined temperature and humidity. The housing may include a bottom portion, a top portion, and at least one side portion, preferably four side portions. The bottom portion, top portion, and at least one side portion at least partially define the housing volume. The bottom portion, top portion, and at least one side portion may be connected to each other to form an integrated component. Furthermore, the housing may be provided with an electrical grounding connection, allowing the housing to increase the safety of personnel near the electrical components enclosed by the housing in a specified manner.

[0029] In the context of this invention, the two parts forming an integrated component are interconnected by at least one mechanical connection. In other words, when the integrated component moves from one spatial location to another, the two parts forming the integrated component change their spatial position relative to each other within the range of their mechanical connection.

[0030] In a preferred embodiment of the invention, the mechanical connection of the integrated components is fixed. In other words, the relative positions of the two parts forming the integrated components remain constant during changes in the spatial position of the integrated components, wherein the mechanical connection between the two parts is fixed.

[0031] The rectifier stage includes at least one rectifier circuit, preferably two or more, three or more, four or more, five or more, or six or more rectifier circuits. The rectifier stage and / or rectifier circuits are configured to convert alternating current and alternating voltage into direct current and direct current. Preferably, the rectifier stage and / or rectifier circuits are configured to convert all phases of a multiphase alternating current into direct current.

[0032] A rectifier circuit can be a three-phase rectifier circuit. A three-phase rectifier circuit is configured to convert all three phases of a three-phase alternating current into direct current.

[0033] In a preferred embodiment, the rectifier circuits are connected in parallel with each other.

[0034] A rectifier circuit may include an uncontrolled diode bridge. A rectifier stage that includes a rectifier circuit designed in this way can also be referred to as a diode front end (DFE). A DFE is a unidirectional converter.

[0035] A unidirectional converter allows electrical energy to flow essentially in one direction and blocks electrical energy in the opposite direction. This means that electrical energy can flow from the three-phase grid to the load, preferably the electric furnace, but not from the load to the three-phase grid. Alternatively, electrical energy can flow from the load, preferably the electric furnace, to the three-phase grid, but not from the three-phase grid to the load.

[0036] A converter stage may include at least one inverter circuit, preferably four or more, six or more, or eight or more inverter circuits. Such a converter stage is configured to convert direct current and direct current voltage into alternating current and alternating current voltage, preferably into multiphase alternating current and multiphase alternating current voltage. The inverter circuit may be configured to convert direct current and direct current voltage into single-phase alternating current and single-phase alternating current voltage.

[0037] In a preferred embodiment, the inverter circuit is a three-phase inverter circuit. The three-phase inverter circuit is configured to convert direct current and direct current voltage into three-phase alternating current and three-phase alternating current voltage. Each of the three-phase alternating currents may have a phase difference of +120 degrees with one of the two other alternating currents and a phase difference of -120 degrees with the corresponding other alternating current.

[0038] In a preferred embodiment, the inverter circuits of the converter stage are connected in parallel with each other.

[0039] The rectifier circuit and / or inverter circuit may include multiple switching devices connected in parallel and / or in series with each other, wherein the switching devices may include semiconductors, diodes, thyristors such as silicon controlled rectifiers (SCRs), gate turn-off thyristors (GTOs), integrated gate commutated thyristors (IGCTs), metal-oxide-semiconductor controlled thyristors (MCTs), transistors such as bipolar junction transistors (BJTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), and / or insulated-gate bipolar transistors (IGBTs).

[0040] The rectifier stage and / or converter stage can be a bidirectional converter. A bidirectional converter allows electrical energy to flow essentially in both directions, meaning that electrical energy can flow from the three-phase grid to the load, preferably the electric furnace, and from the load, preferably the electric furnace, back to the three-phase grid.

[0041] The bidirectional rectifier stage can also be referred to as the active front end (AFE).

[0042] The switching device can be an integrated component, specifically, an integrated component including a switching device housing. The switching device housing can be fluid-impermeable. The switching device housing can have a cylindrical shape and / or a cubic shape. The switching device housing can include metallic and / or plastic and / or ceramic materials. Specifically, the switching device housing can include a first surface and a second surface opposite to the first surface. The first and / or second surfaces can include metallic and / or plastic materials, or can be composed of metallic and / or plastic materials. The remaining surfaces can include plastic and / or ceramic materials, or can be composed of plastic and / or ceramic materials. In the case of a cylindrical switching device housing, the first and second surfaces correspond to the circular surfaces of the cylinder, and the remaining surfaces correspond to the outer surfaces of the cylinder.

[0043] The first and second surfaces of the switching device housing can be configured to conduct electrical energy, specifically current, from a three-phase power grid to the electric furnace and / or conduct electrical energy from the electric furnace to the three-phase power grid. In the intended use of the furnace power supply device, the first and second surfaces of the switching device housing can be under voltage. The switching device may include one or more press-fit IGBTs, or may be press-fit IGBTs.

[0044] In alternative intended applications of the furnace power supply device, the switching device housing is electrically isolated. Specifically, the switching device, preferably the switching device housing, may be electrically isolated relative to the power module housing. In other words, the switching device and / or the switching device housing may include a floating potential relative to the power module housing. In the context of this invention, a floating potential means that the switching device and / or the switching device housing is at least partially isolated relative to the power module housing. That is, they are electrically isolated relative to the power module housing, and therefore electrically isolated relative to the electrical ground, thereby preventing or at least significantly limiting the generation of parasitic currents to the electrical ground connection.

[0045] The switching device housing may include at least one cooling surface, specifically two cooling surfaces. In a preferred embodiment, the first surface and / or the second surface are configured as cooling surfaces.

[0046] The rectifier circuit and / or inverter circuit may each be an integrated component, specifically an integrated component formed by multiple switching devices electrically connected in parallel and / or in series with each other, wherein the switching devices are at least indirectly mechanically connected to each other.

[0047] In a preferred embodiment, the switching devices of a rectifier circuit are stacked vertically and / or horizontally on top of each other.

[0048] Preferably, the switching devices of a rectifier circuit are stacked vertically and / or horizontally and spaced apart from each other. In other words, there are gaps between the vertically and / or horizontally stacked switching devices of a rectifier circuit. Alternatively, the switching devices of a rectifier circuit are in direct contact with each other, more preferably in direct surface contact.

[0049] More preferably, a stack of switching devices of a rectifier circuit is arranged in the frame structure.

[0050] The frame structure may include a first frame end plate and a second frame end plate, and at least one connecting element, preferably four connecting elements, mechanically connecting the first and second frame end plates to each other. Switching devices, preferably vertically and / or horizontally stacked, may be arranged between the first and second frame end plates. In this way, the switching devices and the frame structure form an integrated component. In other words, the rectifier circuit forms an integrated component.

[0051] In a preferred embodiment, the switching devices of an inverter circuit are stacked vertically and / or horizontally on top of each other.

[0052] Preferably, the switching devices of an inverter circuit are stacked vertically and / or horizontally and spaced apart from each other. In other words, there are gaps between the vertically and / or horizontally stacked switching devices of an inverter circuit. Alternatively, the switching devices of an inverter circuit are in direct contact with each other, more preferably in direct surface contact.

[0053] More preferably, the stacked switching devices of an inverter circuit are arranged in the frame structure.

[0054] The frame structure may include a first frame end plate and a second frame end plate, and at least one connecting element, preferably four connecting elements, mechanically connecting the first and second frame end plates to each other. Switching devices, preferably vertically or horizontally stacked, may be arranged between the first and second frame end plates. In this way, the switching devices and the frame structure form an integrated component. In other words, the inverter circuitry forms an integrated component.

[0055] The connecting element can mechanically connect the first frame end plate and the second frame end plate, and apply compressive force to the first frame end plate, the second frame end plate, and the stacked switching devices disposed therebetween, specifically to the housings of the stacked switching devices. The connecting element can be a connecting rod, bolt, screw, etc.

[0056] The rectifier stage and / or converter stage can be housed within the power module housing.

[0057] The rectifier stage may include multiple frame structures of switching devices. The multiple frame structures of switching devices may be stacked vertically and / or horizontally on top of each other.

[0058] A converter stage may include multiple frame structures of switching devices. These multiple frame structures of switching devices may be stacked vertically and / or horizontally on top of each other.

[0059] Alternatively, the converter stage may include at least one DC chopper circuit, preferably two or more, three or more, four or more, five or more, or six or more DC chopper circuits. The DC chopper circuits are configured to directly convert DC current with a fixed voltage level into DC current with a variable voltage level. Such a converter stage is configured to directly convert DC current with a fixed voltage level into DC current with variable current and voltage levels.

[0060] In a preferred embodiment, the DC chopper circuits are connected in parallel and / or in series with each other.

[0061] Because the switching devices in a DC chopper circuit are fully on or fully off, its losses are low and the DC chopper circuit can provide high efficiency, wherein the switching rate is greater than or equal to 1 kHz, preferably greater than or equal to 2 kHz, and particularly preferably greater than or equal to 5 kHz. Advantageously, the DC chopper circuit can have a switching rate greater than or equal to 10 kHz, preferably greater than or equal to 15 kHz, and particularly preferably greater than or equal to 20 kHz. In this way, the arc can be advantageously stabilized while protecting the furnace power supply from possible drift.

[0062] DC chopper circuits may include multiple switching devices connected in parallel and / or in series with each other, wherein the switching devices include semiconductors, diodes, thyristors such as silicon controlled rectifiers (SCRs), gate turn-off thyristors (GTOs), integrated gate commutated thyristors (IGCTs), metal-oxide-semiconductor controlled thyristors (MCTs), transistors such as bipolar junction transistors (BJTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), and / or insulated-gate bipolar transistors (IGBTs).

[0063] A DC chopper circuit can be current-isolated. Specifically, a DC chopper circuit can include at least one power-conducting element that provides current isolation. The power-conducting element can be an inductive element, specifically a magnetic coil. More specifically, a DC chopper circuit can include two magnetic coils. The power-conducting element can be a transformer.

[0064] The DC chopper circuit can be a bidirectional DC chopper circuit. Alternatively, the DC chopper circuit can be a unidirectional DC chopper circuit.

[0065] DC chopper circuits can be configured as flyback converters, forward converters, or push-pull converters.

[0066] The DC chopper circuit can be an integrated component. In a preferred embodiment, the DC chopper circuit includes multiple switching devices, each of which is mounted on a combined heatsink.

[0067] The DC bus may include one or more capacitors and / or coils connected in series and / or parallel to each other to store energy and create electrical isolation between the rectifier stage and the converter stage. Electrical isolation can be achieved by storing electrical energy in the DC bus and / or its capacitors and / or coils. The stored electrical isolation can absorb fluctuations in power supply and / or demand, specifically transient fluctuations.

[0068] The DC bus may include, or may consist of, power cables and / or busbars. The DC bus may be part of the power module. The DC bus may be housed within the power module housing.

[0069] Preferably, the power module may include multiple DC buses connected in parallel with each other. Specifically, one DC bus connects one rectifier circuit to exactly one inverter circuit or DC chopper circuit. In other words, there is a one-to-one connection between the rectifier circuit, the DC bus, and the inverter circuit or DC chopper circuit. Further, one DC bus is connected to only one rectifier circuit and also to only one inverter circuit or DC chopper circuit.

[0070] The power module may include a DC / DC converter circuit connected to the rectifier stage. Specifically, the DC / DC converter circuit may be connected to the rectifier stage via a DC bus. In a preferred embodiment, the furnace power supply may include two DC buses, wherein a first DC bus connects the rectifier stage to the DC / DC converter circuit and a second DC bus connects the DC / DC converter circuit to the converter stage of the power module. In other words, the two DC buses are connected in series with each other.

[0071] A DC / DC converter circuit is an electrical device that converts direct current with a first voltage level into direct current with a second voltage level.

[0072] In the context of this invention, the first voltage level is the voltage level of the current entering the DC / DC converter circuit in the direction of electrical energy delivery. The current entering the DC / DC converter circuit can deliver electrical energy from a three-phase power grid and / or another DC power source to a load, or from a load to a three-phase power grid and / or another DC power source.

[0073] In the context of this invention, the second voltage level is the voltage level of the current exiting the DC / DC converter circuit in the direction of electrical energy delivery. The current exiting the DC / DC converter circuit can deliver electrical energy from the three-phase grid and / or another DC power source to the load, or from the load to the three-phase grid and / or another DC power source.

[0074] The first voltage level may be higher or lower than the second voltage level. Alternatively, the first voltage level may be equal to the second voltage level.

[0075] The DC / DC converter circuit can be configured to provide a constant second voltage level. This constant second voltage level can vary from the nominal second voltage level by less than or equal to 80%, or less than or equal to 60%, or less than or equal to 50%, or less than or equal to 40%, or less than or equal to 30%, or less than or equal to 20%, or less than or equal to 15%, or less than or equal to 10%, or less than or equal to 5%. The voltage variation can be measured as a given number of average voltage values ​​over a predetermined time interval, which must be within a specified range near the nominal voltage level. For example, for a 20% deviation of the second voltage level from the specified nominal voltage level, 95% of the 1-minute average of the measured voltage values ​​at hourly intervals must be within the limit of the 20% deviation from the nominal voltage level. The time interval can be varied. The required given number of average voltage values ​​can be varied. Alternatively or additionally, the voltage variation can be measured according to one of the measurement principles of DIN EN 50160, DIN EN 61000-2-2, or DIN EN 61000-2-4, or any other standard suitable for the application.

[0076] DC / DC converter circuits may include multiple switching devices connected in parallel and / or in series with each other, wherein the switching devices may be of the same type as the switching devices in a DC chopper circuit.

[0077] The DC / DC converter circuit can be an integrated component. In a preferred embodiment, the DC / DC converter circuit includes multiple switching devices, each of which is mounted on a combined heatsink.

[0078] DC / DC converter circuits can be configured to handle voltage levels higher than or equal to 500VDC, specifically higher than or equal to 1000VDC, and even more specifically higher than or equal to 2000VDC.

[0079] DC / DC converter circuits can be current-isolated. Specifically, a DC / DC converter circuit can include at least one power-conducting element that provides current isolation. The power-conducting element can be an inductive element, specifically a magnetic coil. More specifically, a DC / DC converter circuit can include two magnetic coils. The power-conducting element can be a transformer.

[0080] The DC / DC converter circuit can be a bidirectional DC / DC converter circuit. Alternatively, the DC / DC converter circuit can be a unidirectional DC / DC converter circuit.

[0081] Preferably, the power module may include multiple DC buses connected in parallel with each other, one of which connects a rectifier circuit to a DC / DC converter circuit and an inverter circuit or DC chopper circuit. In other words, there is a one-to-one connection between the rectifier circuit, the DC bus, the DC / DC converter circuit, and the inverter circuit or DC chopper circuit. Further, a DC bus may be connected to only one rectifier circuit, only one DC / DC converter circuit, and only one inverter circuit or DC chopper circuit.

[0082] The furnace power supply unit may include an auxiliary power source independent of the three-phase power grid. This auxiliary power source may include renewable energy sources such as wind turbines and / or wind turbine power plants and / or solar power plants and / or geothermal power plants and / or wave power plants and / or batteries. The auxiliary power source may also include non-renewable energy sources such as nuclear power plants, coal-fired power plants, gas-fired power plants, and / or oil-fired power plants. The auxiliary power source can provide direct current (DC) and / or alternating current (AC).

[0083] According to a preferred embodiment, at least one auxiliary power source is at least indirectly, preferably directly, connected to one or more DC buses of one or more power modules of the furnace power supply unit. In this way, a stable energy supply can be provided to the furnace power supply unit even in the event of interference and / or faults in the three-phase power grid.

[0084] An auxiliary power supply can provide a voltage level that is substantially the same as the DC bus voltage level, either directly or indirectly. In this way, power can be supplied with minimal interference to the DC bus.

[0085] An auxiliary power supply may be indirectly connected to one or more DC buses of one or more power modules via one or more DC connector circuits configured to provide a first voltage level and / or a second voltage level matching the voltage level of the auxiliary power supply and / or the DC bus, depending on the direction of power delivery. In other words, when power flows from the auxiliary power supply to the DC bus, the DC connector circuit can handle a first voltage level substantially the same as the voltage level provided by the auxiliary power supply and provide a second voltage level substantially the same as the voltage level of the DC bus. When power flows from the DC bus to the auxiliary power supply, the DC connector circuit can handle a first voltage level substantially the same as the voltage level provided by the DC bus and provide a second voltage level substantially the same as the voltage level of the auxiliary power supply. The DC connector circuit may include at least one DC / DC converter circuit.

[0086] The auxiliary power supply can be connected, at least indirectly and preferably directly, between the three-phase power grid and the rectifier stage of the furnace power supply. In a preferred embodiment, the auxiliary power supply is connected between the three-phase power grid and the rectifier stage. Specifically, the auxiliary power supply is connected between at least one transformer and the rectifier stage. The auxiliary power supply can be connected between at least one transformer and the rectifier stage via an AC connector circuit. The AC connector stage can be configured to provide a first voltage level and / or a second voltage level matching the voltage level provided by one or more secondary circuits of the three-phase transformer and / or the auxiliary power supply, depending on the direction of power delivery. In other words, when power flows from the auxiliary power supply to the connection between the three-phase transformer and the rectifier stage, the AC connector circuit can handle a first voltage level substantially the same as the voltage level provided by the auxiliary power supply and provide a second voltage level substantially the same as the voltage level of one or more secondary circuits of the three-phase transformer. When power flows from the connection between the three-phase transformer and the rectifier stage to the auxiliary power supply, the AC connector circuit can handle a first voltage level substantially the same as the voltage level provided by one or more secondary circuits of the three-phase transformer and provide a second voltage level substantially the same as the voltage level of the auxiliary power supply. The AC connector circuit may include at least one inverter circuit and / or at least one rectifier circuit.

[0087] The cooling system is configured to provide cooling power to the furnace power supply unit to dissipate heat loss, specifically to provide cooling power to one or more power modules of the furnace power supply unit.

[0088] The cooling system can be housed within the power module housing. Alternatively, the cooling system can be housed in a separate cooling system housing.

[0089] The cooling system may include at least one radiator, preferably multiple radiators. The radiator may be a passive radiator or an active radiator.

[0090] The heat sink may include a first cooling surface and a second cooling surface opposite to the first cooling surface. The heat sink may be a substantially flat component. In a substantially flat component, one direction of extension is significantly smaller than the other two directions of extension. The first cooling surface and the second cooling surface are spaced apart from each other along the shorter direction of extension of the heat sink.

[0091] Passive radiators cannot directly control temperature. A passive radiator may include a cooling body comprising metal and a large surface area to dissipate heat from a heat source to the environment. A passive radiator can be a textured metal cooling body. Passive radiators can also be referred to as air-cooled radiators.

[0092] Active radiators allow for direct temperature control. An active radiator may include a cooling body comprising metal and one or more fluid channels configured to deliver a cooling fluid. In this way, heat from a heat source can be transferred via the cooling body of the active radiator to the cooling fluid and carried away from the heat source by the cooling fluid. In this manner, active radiators can dissipate a greater amount of heat compared to passive radiators. Active radiators may also be referred to as fluid-cooled radiators.

[0093] An active radiator may include a fluid inlet and a fluid outlet, the fluid outlet being fluidly connected to the fluid inlet via one or more fluid passages inside the coolant body.

[0094] A heat sink may be in electrical contact with at least one switching device. A heat sink may be isolated from ground potential. In this way, the generation of parasitic currents to the electrical ground connection can be prevented or at least significantly limited.

[0095] A heat sink can be arranged to make direct surface contact with the switching devices of the rectifier circuit and / or inverter circuit. Specifically, the first cooling surface of the heat sink can make direct surface contact with the cooling surface of the switching device.

[0096] A heat sink can be positioned between two switching devices in a rectifier circuit and / or an inverter circuit. A first surface of the first switching device's housing can directly contact the second cooling surface of the heat sink. Similarly, a second surface of the second switching device's housing can directly contact the first cooling surface of the heat sink. In other words, a heat sink is sandwiched between two switching devices.

[0097] The advantage of furnace power supply units designed in this way lies in their further improved cooling capacity. In the intended application of the furnace power supply unit, cooling power can now be supplied individually to electrical components, specifically to switching devices. This localized cooling of the switching devices allows for the removal of heat losses with further improved efficiency.

[0098] The switching devices of the rectifier circuit and / or inverter circuit can be arranged between two heat sinks. The first surface of the first switching device's housing can directly contact the second cooling surface of the first heat sink. The second surface of the first switching device's housing can directly contact the first cooling surface of the second heat sink. In other words, a switching device is sandwiched between two heat sinks.

[0099] The advantage of furnace power supply units designed in this way lies in further improved cooling capabilities. The switching devices can be cooled from two surfaces opposite each other, thereby increasing the removal of potential heat losses. Therefore, heat losses can be removed more effectively.

[0100] An integrated component that includes a stack of switching devices and a heat sink, comprising a frame structure and rectifier circuitry, can also be referred to as a rectifier stack.

[0101] By way of non-limiting example, a rectifier stack comprising horizontally stacked switching devices and heat sinks is described below. The rectifier stack comprises the following components in the following order: a first frame end plate, a first heat sink, a switching device, a second heat sink, and a second frame end plate. The first frame end plate has direct surface contact with a first cooling surface of the first heat sink. The second cooling surface of the first heat sink has direct surface contact with a first surface of the switching device housing of the switching device. The second surface of the switching device housing of the switching device has direct surface contact with the first cooling surface of the second heat sink. The second cooling surface of the second heat sink has direct surface contact with the second frame end plate. The first and second frame end plates are mechanically connected to each other via four connecting elements, preferably connecting rods, and apply compressive forces to the stacked heat sinks and switching device housings.

[0102] An integrated component that includes a stack of switching devices and heat sinks, including a frame structure and inverter circuitry, can also be referred to as an inverter stack.

[0103] By way of non-limiting example, an inverter stack comprising vertically stacked switching devices and heat sinks is described below. The inverter stack comprises the following components in the following order: a first frame end plate, a first heat sink, a first switching device, a second heat sink, a second switching device, a third heat sink, and a second frame end plate. The first frame end plate has direct surface contact with a first cooling surface of the first heat sink. The second cooling surface of the first heat sink has direct surface contact with a first surface of the switching device housing of the first switching device. The second surface of the switching device housing of the first switching device has direct surface contact with the first cooling surface of the second heat sink. The second cooling surface of the second heat sink has direct surface contact with the first surface of the switching device housing of the second switching device. The second surface of the switching device housing of the second switching device has direct surface contact with the first cooling surface of the third heat sink. The second cooling surface of the third heat sink has direct surface contact with the second frame end plate. The first and second frame end plates are mechanically connected to each other via four connecting elements, preferably connecting rods, and apply compressive force to the stacked heat sinks and switching device housings.

[0104] By way of non-limiting example, an embodiment of a DC chopper circuit comprising multiple switching devices mounted on a combined heatsink is described below. The DC chopper circuit includes a heatsink and multiple switching devices, each of which includes a separate switching device housing. The switching device housings are mounted on the same surface of the heatsink. The switching device housings are arranged in a matrix structure, i.e., they are arranged in rows and columns on the heatsink. The cooling surfaces of the switching device housings are in direct surface contact with the cooling surfaces of the heatsink. The switching devices are electrically isolated from the heatsink.

[0105] The furnace power supply unit may include an electronic control unit. The electronic control unit is any electronic system adapted to receive and / or store signals and / or process signals and / or control or regulate the furnace power supply unit based on at least one signal.

[0106] The furnace power supply unit may include one or more sensors to provide information about harmonic distortion and / or flicker in the power grid and / or the ratio of active power flow to reactive power flow. An electronic control unit may be operatively connected to one or more such sensors and is capable of receiving sensor signals, processing these sensor signals, and using these sensor signals to control or regulate the furnace power supply unit.

[0107] Electronic control units can be adapted to control and / or regulate rectifier stages, specifically rectifier circuits, particularly to reduce or prevent harmonic distortion and / or flicker in the power grid, especially to mitigate flicker.

[0108] Electronic control units can be adapted to control and / or regulate converter stages, specifically inverter circuits or DC chopper circuits, particularly to reduce or prevent harmonic distortion and / or flicker in the power grid, especially to mitigate flicker, and / or optimize the ratio of active power flow to reactive power flow in the power grid.

[0109] The electronic control unit can be arranged to control and / or regulate the DC chopper circuit or inverter circuit, particularly to reduce or prevent harmonic distortion and / or flicker in the power grid, especially to mitigate flicker, particularly preferably by applying a pulse width modulation strategy algorithm.

[0110] Preferably, the cooling system includes a first cooling circuit configured to direct cooling fluid to and away from the power module.

[0111] The first cooling circuit may include at least one component supply line and at least one component discharge line, the at least one component discharge line being fluidly connected to the at least one component supply line to form a component cooling circuit. The component supply line may be connected to the fluid inlet of an active radiator, and the component discharge line may be connected to the fluid outlet of an active radiator, thereby fluidly connecting the component supply line and the component discharge line via fluid passages of the active radiator.

[0112] The advantage of furnace power supply units designed in this way lies in the further improved cooling capacity. In the intended application of the furnace power supply unit, cooling power can now be supplied separately to electrical components, specifically to switching devices. In this way, heat loss can be eliminated with further improved efficiency.

[0113] Component supply lines and component discharge lines can be fluidly connected via a fluid conduit. The fluid conduit may include at least one winding. Preferably, the fluid conduit comprises a helical form including multiple windings. The fluid conduit may at least partially limit the component receiving volume. The component receiving volume may be configured to receive a switching device, preferably a switching device with a cylindrical switching device housing.

[0114] The advantage of furnace power supply units designed in this way lies in the further improved cooling capacity. In the intended application of the furnace power supply unit, cooling power can now be supplied separately to electrical components, specifically to switching devices. In this way, heat loss can be eliminated with further improved efficiency.

[0115] The first cooling loop may include a stacked supply line and a stacked discharge line, the stacked discharge line being fluidly connected to the stacked supply line to form a stacked cooling loop.

[0116] The component supply line can be fluidly connected to the stack supply line, and the component discharge line can be fluidly connected to the stack discharge line. In other words, the stack supply line and the stack discharge line can be fluidly connected via a component cooling loop formed by the component supply line and the component discharge line.

[0117] The first cooling circuit may include a first main supply line and a first main discharge line, the first main discharge line being fluidly connected to the first main supply line.

[0118] The stacked supply line can be fluidly connected to the first main supply line, and the stacked discharge line can be fluidly connected to the first main discharge line. In other words, the first main supply line and the first main discharge line can be fluidly connected via a stacked cooling loop formed by the stacked supply line and the stacked discharge line.

[0119] The first main supply line and the first main discharge line can be arranged outside the power module housing, preferably below the power module housing. In this way, each stacked cooling circuit can have the same cooling fluid temperature at the stacked supply line. In this way, heat loss can be eliminated with improved accuracy.

[0120] The power module housing may include at least one stacked cooling circuit inlet, preferably arranged in the bottom portion of the power module housing, and at least one stacked cooling circuit outlet, preferably arranged in the bottom portion of the power module housing.

[0121] The stacked cooling loop can be partially arranged within the power module housing. Specifically, the stacked supply line can begin outside the power module housing and enter the power module housing. Preferably, the stacked supply line enters the power module housing through a stacked cooling loop inlet. The stacked discharge line can begin inside the power module housing and exit the power module housing. Preferably, the stacked discharge line exits the power module housing through a stacked cooling loop outlet. In this type of stacked cooling loop, cooling fluid flowing in the main supply line can enter the stacked supply line outside the power module housing, flow through a portion of the stacked cooling loop inside the power module housing, and exit the power module housing through the stacked discharge line. Cooling fluid can enter the main discharge line from the stacked discharge line.

[0122] The component cooling circuit can be arranged in the power module housing.

[0123] Preferably, the first main supply line and the first main discharge line are arranged horizontally. The stacked supply lines and the stacked discharge lines are preferably arranged vertically. The component supply lines and the component discharge lines are preferably arranged horizontally.

[0124] Alternatively, the main supply lines and main discharge lines are arranged vertically. Stacked supply lines and stacked discharge lines are preferably arranged horizontally. Component supply lines and component discharge lines are preferably arranged vertically or horizontally.

[0125] In this context, a horizontal arrangement means that the flow direction of the cooling fluid is essentially horizontal. A vertical arrangement in this context means that the flow direction of the cooling fluid is essentially vertical.

[0126] The main supply line and main discharge line may include, or may be composed of, metallic materials. Stacked supply lines, stacked discharge lines, component supply lines, and component discharge lines may include, or may be composed of, plastic materials.

[0127] The advantage of furnace power supply units designed in this way is enhanced protection against electrical faults caused by fluid leakage in the cooling circuit. In the event of a leakage in the cooling circuit, the cooling fluid may potentially come into contact with electrical components under voltage, resulting in unwanted current and / or voltage within the cooling circuit. By designing portions of the cooling circuit from a ductile material, the conductivity is significantly reduced, thereby improving protection against unwanted current and voltage in the cooling circuit.

[0128] The main supply line and the main discharge line may each have a larger diameter than the stacked supply line, the stacked discharge line, the component supply line, and the component discharge line. The stacked supply line and the stacked discharge line may each have a larger diameter than the component supply line and the component discharge line.

[0129] The cooling system may include multiple stacked cooling loops. Specifically, the cooling system may include one stacked cooling loop for each rectifier stack and one stacked cooling loop for each inverter stack of power modules. The multiple stacked cooling loops may be fluidly connected to the same main discharge line and main supply line.

[0130] The cooling system may include multiple component cooling loops. Specifically, the cooling system may include at least one component cooling loop for each active heatsink of the power module. Component supply lines and component discharge lines connected to the active heatsinks of a rectifier stack or an inverter stack may be fluidly connected to the same stack cooling loop of the respective rectifier stack or inverter stack.

[0131] In the intended use of the furnace power supply unit, cooling power can now be supplied separately to electrical components, specifically to switching devices. In this way, heat loss can be eliminated with further improved efficiency.

[0132] The cooling fluid may include water or water, preferably deionized water, more preferably deionized water with a conductivity in the range of ≥1 μS / cm and ≤50 μS / cm, preferably in the range of ≥0.5 μS / cm and ≤1 μS / cm, and even more preferably in the range of ≥0.1 μS / cm and ≤0.5 μS / cm. Particularly preferably, the conductivity of the deionized water may be in the range of ≥0.055 μS / cm and ≤0.1 μS / cm.

[0133] The advantage of furnace power supply units designed in this way is enhanced protection against unwanted current and / or voltage in the cooling circuit.

[0134] The cooling circuit may include heat exchange elements to remove heat from the cooling fluid, specifically deionized water. In this way, the deionized water circuit can be separated from the raw water circuit.

[0135] The heat exchange element can be a plate heat exchanger.

[0136] The furnace power supply unit may include a separate cooling system for each power module. Alternatively, the furnace power supply unit may include a single cooling system for multiple power modules. The cooling system may include multiple cooling circuits, preferably a separate cooling circuit for each power module. In other words, the number of cooling circuits may be the same as the number of power modules.

[0137] The first cooling circuit may include multiple valves, specifically located between the first cooling fluid pump and / or the second cooling fluid pump and the first main supply line and the first main discharge line. Further, one or more valves may be arranged between the first main supply line and the stack supply line. Further, one or more valves may be arranged between the first main discharge line and the stack discharge line. Further, one or more valves may be arranged between the stack supply line and the component supply line. Further, one or more valves may be arranged between the stack discharge line and the component discharge line. One or more valves may be movable between an open position and a closed position.

[0138] In this way, the first cooling circuit can be interrupted to shorten maintenance time and / or to replace individual components of the power module, such as the rectifier stage, converter stage, rectifier stack and / or inverter stack.

[0139] Preferably, the cooling system includes a first cooling fluid pump configured to deliver cooling fluid through a first cooling circuit.

[0140] The cooling system may include a second cooling fluid pump. This second cooling fluid pump may be a standby pump configured to automatically activate in the event of a defect or failure of the first cooling fluid pump. The first and second cooling fluid pumps may be of the same type.

[0141] Cooling fluid pumps can be housed within the cooling system casing. Cooling fluid pumps can be flow pumps, specifically axial flow pumps, radial flow pumps, or a combination of both. Cooling fluid pumps can also be positive displacement pumps, specifically piston pumps, specifically rotary piston pumps or axial piston pumps, diaphragm pumps, screw conveyor-based pumps, or impeller-based pumps.

[0142] The cooling fluid pump can be configured to deliver cooling fluid through a first cooling circuit and / or a second cooling circuit at a rate of ≥100 l / min, preferably ≥250 l / min, preferably ≥500 l / min, and particularly preferably ≥1000 l / min.

[0143] Preferably, the cooling system includes a filtration system, more preferably a deionization system, which is configured to regulate and / or control the conductivity of the cooling fluid.

[0144] The filtration system can be configured to adjust and / or control the conductivity of the cooling fluid to a range of ≥1 μS / cm and ≤50 μS / cm, preferably ≥0.5 μS / cm and ≤1 μS / cm, and more preferably ≥0.1 μS / cm and ≤0.5 μS / cm. Particularly preferably, the filtration system can be configured to adjust and / or control the conductivity of the cooling fluid to a range of ≥0.055 μS / cm and ≤0.1 μS / cm.

[0145] The advantage of furnace power supply units designed in this way is enhanced protection against unwanted current and / or voltage in the cooling circuit.

[0146] Preferably, the cooling system includes at least one air conditioning system.

[0147] The air conditioning system can be configured to supply cooling power to the power module. Specifically, the air conditioning system can be configured to dissipate heat and moisture from the air within the power module housing volume.

[0148] The air conditioning system may include at least one main air supply duct. The main air supply duct may be located outside the power module housing, preferably below the power module housing. The main air supply duct may be arranged horizontally.

[0149] The air conditioning system may include at least one air supply duct, preferably multiple air supply ducts. The air supply ducts may be fluidly connected to a main air supply duct. The air supply ducts may be arranged vertically. The air supply ducts may be located outside the power module housing, preferably below the power module housing.

[0150] The power module housing may include at least one air supply inlet, which is preferably located in the bottom portion of the power module housing. An air supply duct may be fluidly connected to the power module housing volume via the air supply inlet.

[0151] The power module housing may include at least one air exhaust outlet, preferably multiple air exhaust outlets. The air exhaust outlets are preferably located in the top or side portion of the power module housing.

[0152] The air conditioning system may include at least one heat exchange element configured to remove heat and moisture from the air in the power module housing to the environment.

[0153] The heat exchange elements can be arranged in the cooling system housing. Alternatively, the heat exchange elements can be arranged in the power module housing, specifically in the top portion or the side portion of the power module housing.

[0154] The cooling system can be configured to provide cooling power to the power module via a first cooling circuit and an air conditioning system. The cooling power can be provided in such a manner that a portion of the cooling power is provided by the first cooling circuit, and a corresponding portion is provided by the air conditioning system. Specifically, the portion of the cooling power provided by the first cooling circuit can be ≥70% of the total cooling power, and the portion of the cooling power provided by the air conditioning system can be ≤30% of the total cooling power. Alternatively, the portion of the cooling power provided by the first cooling circuit can be ≥80% of the total cooling power, and the portion of the cooling power provided by the air conditioning system can be ≤20% of the total cooling power. According to a preferred embodiment, the portion of the cooling power provided by the first cooling circuit can be ≥90% of the total cooling power, and the portion of the cooling power provided by the air conditioning system can be ≤10% of the total cooling power.

[0155] Total cooling power is the amount of cooling power supplied by the cooling system to the power module at any given time.

[0156] Preferably, the cooling system includes a temperature and humidity control unit configured to regulate and / or control the temperature of the power module and / or the humidity of the power module housing volume.

[0157] A temperature and humidity control unit is any electronic system adapted to receive and / or store signals and / or process signals and / or control and / or regulate the temperature of the power module of the furnace power supply unit and / or the humidity of the power module housing volume according to at least one signal.

[0158] The furnace power supply unit may include one or more sensors to provide information about the temperature of the power module and / or the humidity of the power module housing volume. A temperature and humidity control unit may be operatively connected to one or more such sensors and may receive, process, and use these sensor signals to control and / or regulate the temperature of the power module and / or the humidity of the power module housing volume. The temperature and humidity control unit may be operatively connected to a cooling system, specifically a cooling fluid pump and an air conditioning system.

[0159] The sensor can be a temperature and / or humidity sensor. The sensor can be located at the rectifier stage, the DC bus, the converter stage, and / or inside the power module housing.

[0160] The temperature and humidity control unit can be adapted to individually regulate and / or control the temperature of the rectifier stage, DC bus, and / or converter stage. Specifically, the temperature and humidity control unit can be adapted to regulate and / or control the temperature and / or humidity of the power module housing volume.

[0161] The temperature and humidity control unit is adapted to regulate and / or control the temperature and / or humidity of the rectifier stage, DC bus, and / or converter stage, and / or the power module housing volume, according to the control and / or regulation of the electronic control unit. In cases where a large amount of electrical energy is required during the intended use of the furnace power supply, such as at the beginning and during the melting process in an electric furnace, a greater amount of cooling power is needed. Therefore, the temperature and humidity control unit is configured to receive sensor signals, process these sensor signals, and use these sensor signals to control and / or regulate the cooling system to provide a large amount of cooling power to the power module housing volume, rectifier stage, DC bus, and / or converter stage, specifically by increasing the cooling fluid volumetric flow rate of at least one first cooling circuit and / or by increasing the air volumetric flow rate of the air conditioning system.

[0162] Preferably, the furnace power supply device includes a power module housing, wherein the power module housing at least partially restricts the power module housing volume, and the power module is arranged in the power module housing volume.

[0163] Preferably, the power module housing limits the amount of electromagnetic field emitted.

[0164] Preferably, the power module housing comprises a conductive material, specifically a metal. In this way, the housing can reduce the amount of electromagnetic field emission caused by the high current flowing through the electrical components inside the housing. Therefore, human exposure to electromagnetic fields is reduced.

[0165] Preferably, the power module housing includes an electromagnetic shielding device. More preferably, the electromagnetic shielding device may include, or may be composed of, a metal mesh. The metal mesh may be arranged within the volume of the power module housing. In this way, the amount of electromagnetic field emitted by the high current flowing through the electrical components inside the housing is further reduced.

[0166] Alternatively or additionally, the power module housing can be designed as an electromagnetic shielding device.

[0167] Preferably, the casing is connected to ground potential.

[0168] Preferably, the furnace power supply device includes at least one three-phase transformer, wherein each phase of the three-phase transformer includes a primary circuit and each phase includes one or more secondary circuits.

[0169] The primary circuit of the three-phase transformer can be connected to a three-phase power grid. One or more secondary circuits can be connected to at least one power module of the furnace power supply unit, preferably to the rectifier stage, and more preferably to at least one three-phase rectifier circuit of the furnace power supply unit.

[0170] One or more secondary circuits of each phase of a three-phase transformer can be connected to exactly one power module. In other words, one or more secondary circuits of each phase of a three-phase transformer can be connected to the same power module. Preferably, the furnace power supply unit includes multiple three-phase transformers, wherein each transformer is connected to exactly one power module. In other words, there is a one-to-one connection between the three-phase transformers and the power modules.

[0171] Preferably, the three-phase transformer is a phase-shifting transformer.

[0172] A phase-shifting transformer is a specialized type of transformer that can be configured to adjust the phase relationship between its primary circuit and its secondary circuit. The advantage of a furnace power supply unit designed in this way is that it can control, and preferably minimize, undesirable grid distortion caused by furnace operation without requiring an active front end.

[0173] Preferably, the three-phase transformer is a dry-type transformer.

[0174] A dry-type transformer is a type of transformer that does not use liquid as a cooling medium or as an insulating medium for its windings and core. Instead, it uses a gaseous fluid, preferably air, as the cooling medium and a solid material, preferably epoxy resin, polyester resin, and / or aramid material, as the insulating medium. The advantage of furnace power supply units designed in this way is that they facilitate initial installation and reduce fire hazards during failures caused by the combustion of the cooling medium.

[0175] Preferably, the furnace power supply device includes an isolator, wherein the isolator is arranged between the converter stage and the electric furnace.

[0176] The isolator is configured to interrupt the electrical connection between the converter stage and the electric furnace.

[0177] The furnace power supply unit may include one or more isolators arranged between the three-phase power grid and the electric furnace, specifically between the three-phase power grid and the rectifier stage, between the rectifier stage and the converter stage, between the rectifier stage and the DC bus, between the DC bus and the converter stage, and / or between the converter stage and the electric furnace.

[0178] The isolator can be configured to connect the primary winding of the transformer to ground potential when the isolator is in the open position.

[0179] Preferably, the rectifier stage of the power module includes at least one three-phase rectifier circuit, and at least one three-phase rectifier circuit of each power module is connected to the DC bus.

[0180] Preferably, the furnace power supply device includes multiple power modules connected in parallel with each other.

[0181] Preferably, at least one three-phase rectifier circuit of the rectifier stage of the first power module and at least one three-phase rectifier circuit of the rectifier stage of the second power module are connected to the same DC bus.

[0182] Preferably, the furnace power supply device includes a rectifier-level isolator, wherein the rectifier-level isolator is arranged between the rectifier stage and the DC bus.

[0183] Preferably, the rectifier-stage isolator is arranged between at least one three-phase rectifier and the DC bus to which the at least one three-phase rectifier is connected.

[0184] Preferably, the furnace power supply device includes an inverter-level isolator, wherein the inverter-level isolator is arranged between the inverter stage and the DC bus.

[0185] Preferably, the converter stage includes at least one multiphase inverter circuit, preferably a three-phase inverter circuit, which is configured to supply power to at least two different phases of the electric furnace.

[0186] Preferably, the furnace power supply device includes at least two power modules, wherein the first converter stage of the first power module and the second converter stage of the second power module are connected to the same DC bus.

[0187] Preferably, the furnace power supply device includes at least two power modules, wherein the converter stage of each power module includes at least two single-phase inverter circuits, wherein each single-phase inverter circuit is configured to supply power to different phases of the furnace, and wherein single-phase inverter circuits configured to supply power to the same phase of the furnace are connected to the same DC bus.

[0188] Preferably, the furnace power supply device includes at least two DC buses, wherein a single-phase inverter circuit configured to supply power to a first phase of the furnace is connected to a first DC bus, and wherein a single-phase inverter circuit configured to supply power to a second phase of the furnace is connected to a second DC bus.

[0189] Preferably, the ratio of the number of inverter circuits to the number of three-phase rectifier circuits within a power module is two or greater.

[0190] Preferably, the single-phase inverter circuits of the inverter stage of the power module are connected to each other in a star configuration.

[0191] Preferably, the star centers of each inverter stage of the power module are connected to the neutral line (N).

[0192] Preferably, the single-phase inverter circuit or three-phase inverter circuit of the inverter stage of the power module is connected to each other in a delta connection.

[0193] The problem behind this invention is also solved by an electric furnace that includes at least one furnace power supply device as described above.

[0194] The problem behind this invention is also addressed by a production line for processing metal workpieces, the production line comprising at least one furnace power supply device as described above and at least one metal workpiece processing device.

[0195] Metal workpiece processing equipment can be a rolling mill, a stamping mill, a pressure quenching machine, or any other machine suitable for processing metal workpieces.

[0196] Further advantages, details and features of the invention are explained in the following description of embodiments, thereby: Figure 1 A schematic diagram of a first embodiment of the furnace power supply device is shown; Figure 2 A schematic diagram of a second embodiment of the furnace power supply device is shown; and Figure 3A schematic diagram of an inverter stack for a furnace power supply unit according to a third embodiment is shown.

[0197] In the following description, the same reference numerals describe the same elements and the same features respectively, such that a description of an element with reference to one figure is also valid for other figures, thus omitting the repetition of corresponding features.

[0198] Figure 1 A furnace power supply device 20 for supplying electrical energy to an electric furnace according to a first embodiment is shown. The furnace power supply device 20 is connected to a three-phase power grid 10 and an electrode 30 of the electric furnace. The furnace power supply device 20 includes a power module 100, wherein the power module 100 includes a rectifier stage 110 connected to the three-phase power grid 10 and a converter stage 120 connected to the electrode 30 of the electric furnace. The furnace power supply device 20 includes a DC bus 130, wherein the DC bus 130 connects the rectifier stage 110 of the power module 100 to the converter stage 120. The furnace power supply device 20 includes a cooling system 140.

[0199] Figure 2 A furnace power supply device 20 according to a second embodiment is shown. The furnace power supply device 20 includes a power module housing 101, wherein the power module housing 101 partially defines a power module housing volume 102, and a power module 100 is arranged in the power module housing volume 102.

[0200] The power module 100 includes a rectifier stage 110, a converter stage 120, and a DC bus 130, wherein the DC bus 130 connects the rectifier stage to the converter stage 120.

[0201] The furnace power supply unit 20 also includes a cooling system 140, wherein the cooling system 140 is arranged in a separate cooling system housing 141.

[0202] The cooling system 140 includes a first cooling circuit 150 configured to direct cooling fluid to and away from the power module 100.

[0203] The first cooling circuit 150 includes a plurality of component cooling circuits 170, wherein each component cooling circuit 170 includes a component supply line 171 and a component discharge line 172, wherein the component supply line 171 is fluidly connected to the component discharge line 172, thereby forming the component cooling circuit 170. The component cooling circuits 170 are arranged in the power module housing 101.

[0204] The first cooling circuit 150 includes two stacked cooling circuits 160, wherein each stacked cooling circuit 160 includes a stacked supply line 161 and a stacked discharge line 162, wherein the stacked supply line 161 is fluidly connected to the stacked discharge line 162, thereby forming the stacked cooling circuit 160.

[0205] Multiple component supply lines 171 are fluidly connected to stack supply lines 161, and multiple component discharge lines 172 are fluidly connected to stack discharge lines 162. In other words, stack supply lines 161 and stack discharge lines 162 are fluidly connected via a component cooling loop 170 formed by component supply lines 171 and component discharge lines 172.

[0206] The first cooling circuit 150 includes a first main supply line 151 and a first main discharge line 152, the first main discharge line being fluidly connected to the first main supply line 151.

[0207] Stacked supply line 161 is fluidly connected to first main supply line 151, and stacked discharge line 162 is fluidly connected to first main discharge line 152. In other words, the first main supply line 151 and the first main discharge line 152 are fluidly connected via a stacked cooling loop 160 formed by the stacked supply line 161 and the stacked discharge line 162.

[0208] The first main supply line 151 and the first main discharge line 152 are arranged outside the power module housing 101 and below the power module housing 101.

[0209] The power module housing 101 includes two stacked cooling loop inlets 163 disposed in the bottom portion 103 of the power module housing 101 and two stacked cooling loop outlets 164 disposed in the bottom portion 103 of the power module housing 101. A stacked supply line 161 begins outside the power module housing 101 and enters the power module housing 101 through the stacked cooling loop inlets 163. A stacked discharge line 162 begins inside the power module housing 101 and exits the power module housing 101 through the stacked cooling loop outlets 164.

[0210] The power module housing 101 is designed as an electromagnetic shielding device 105. The power module housing 101 is electrically connected to the ground 106.

[0211] The first main supply line 151 and the first main discharge line 152 are arranged horizontally. The stacked supply line 161 and the stacked discharge line 162 are arranged vertically. The component supply line 171 and the component discharge line 172 are arranged horizontally.

[0212] Cooling system 140 includes a first cooling fluid pump 153 configured to deliver cooling fluid through a first cooling circuit 150. The first cooling fluid pump 153 is fluidly connected to a first main supply line 151 and a first main discharge line 152 via a filtration system 154. The filtration system is configured to adjust and / or control the conductivity of the cooling fluid to a conductivity in the range of ≥1 μS / cm and ≤50 μS / cm.

[0213] The cooling system 140 also includes an air conditioning system 180. The air conditioning system 180 is configured to supply cooling power to the power module 100. The air conditioning system 180 is configured to dissipate heat from the air in the power module housing volume 102.

[0214] The air conditioning system 180 includes a main air supply duct 181. The main air supply duct 181 is disposed outside the power module housing 101. The main air supply duct 181 is disposed below the power module housing 101. The main air supply duct 181 is arranged horizontally.

[0215] The air conditioning system 180 includes two air supply ducts 183. The air supply ducts 183 are fluidly connected to the main air supply duct 181. The air supply ducts 183 are arranged vertically. The air supply ducts 183 are located outside and below the power module housing 101.

[0216] The power module housing 101 includes at least one air supply inlet 184 disposed in the bottom portion 103 of the power module housing 101. An air supply duct 183 is fluidly connected to the power module housing volume 102 via the air supply inlet 184.

[0217] The power module housing 101 includes an air exhaust outlet 185. The air exhaust outlet 185 is disposed in a side portion 104 of the power module housing 101.

[0218] The air conditioning system 180 includes a heat exchange element 186 configured to remove heat from the air in the power module housing 101 to the environment. The heat exchange element 186 is arranged in the cooling system housing 141.

[0219] The main air exhaust duct 182 fluidly connects the heat exchange element 186 to the power module housing volume 102. The main air exhaust duct 182 is connected to the air exhaust outlet 185 of the power module housing 101.

[0220] Figure 3An inverter stack 200 of a furnace power supply device 20 according to a third embodiment is shown. The inverter stack 200 includes a first frame end plate 410, a first heat sink 250, a first switching device 210, a second heat sink 260, a second switching device 230, a third heat sink 270, and a second frame end plate 420. The first frame end plate 410 is in direct surface contact with a first cooling surface 251 of the first heat sink 250. The second cooling surface 252 of the first heat sink 250 is in direct surface contact with a first surface 221 of a first switching device housing 220 of the first switching device 210. The second surface 222 of the first switching device housing 220 of the first switching device 210 is in direct surface contact with a first cooling surface 261 of the second heat sink 260. The second cooling surface 262 of the second heat sink 260 is in direct surface contact with a first surface 241 of a second switching device housing 240 of the second switching device 230. The second surface 242 of the second switching device housing 240 of the second switching device 230 is in direct surface contact with a first cooling surface 271 of the third heat sink 270. The second cooling surface 272 of the third heat sink is in direct surface contact with the second frame end plate 420. The first frame end plate 410 and the second frame end plate 420 are mechanically connected to each other via four connecting elements 430, and apply compressive force to the stacked heat sinks 250, 260, 270 and switch device housings 220, 240. The heat sinks 250, 260, 270 and switch devices 210, 230 are stacked vertically. The first frame end plate 410, the second frame end plate 420 and the connecting elements 430 form a frame structure 400.

[0221] The inverter stack 200 includes three component cooling circuits 170. Each component cooling circuit 170 includes a component supply line 171 and a component discharge line 172. Each component supply line 171 is connected to a fluid inlet of an active heat sink 250, 260, 270, and each component discharge line 172 is connected to a fluid outlet of an active heat sink 250, 260, 270, thereby fluidly connecting a corresponding component supply line 171 to a component discharge line 172 via fluid passages in the active heat sinks 250, 260, 270.

[0222] Component supply line 171 is fluidly connected to stack supply line 161, and component discharge line 172 is fluidly connected to stack discharge line 162. In other words, stack supply line 161 and stack discharge line 162 are fluidly connected via a component cooling loop 170 formed by component supply line 171 and component discharge line 172.

[0223] List of reference numerals 10 Three-phase power grid Power supply unit for 20 furnaces 30 (Electric furnace) electrodes 100 power module 101 Power Module Housing 102 Power module housing volume 103 (Bottom portion of the power module housing) 104 (Side portion of the power module housing) 105 Electromagnetic shielding device 106 Electrical grounding 110 rectifier stage 120 converter level 130 DC bus 140 Cooling System 141 Cooling system housing 150 First Cooling Circuit 151 First main supply pipeline 152 First Main Discharge Pipeline 153 Cooling fluid pump 154 Filtration System 160 stacked cooling circuit 161 Stacked supply lines 162 Stacked discharge lines 163 Stacked cooling loop inlet 164 Stacked cooling circuit outlet 170 Component Cooling Circuit 171 Component Supply Line 172 component discharge pipeline 180 air conditioning system 181 Main air supply duct 182 Main air exhaust duct 183 Air supply duct 184 Air Supply Inlet 185 Air Emission Exit 186 Heat exchange element 200 inverter stack 210 (Inverter circuit) First switching device 220 (First switching device) First switching device housing 221 (First surface of the first switching device housing) 222 (Second surface of the first switching device housing) 230 (Second switching device in inverter circuit) 240 (Second switching device) Second switching device housing 241 (First surface of the second switching device housing) 242 (Second surface of the second switching device housing) 250 First Radiator 251 (First cooling surface of the first radiator) 252 (Second cooling surface of the first radiator) 260 Second Radiator 261 (First cooling surface of the second radiator) 262 (Second radiator) Second cooling surface 270 Third Radiator 271 (First cooling surface of the third radiator) 272 (Second cooling surface of the third radiator) 400 Frame Structure 410 First frame end plate 420 Second frame end plate 430 Connecting element

Claims

1. A furnace power supply device (20) for supplying electrical energy to an electric furnace. - The furnace power supply device (20) is capable of being connected to a three-phase power grid (10) and at least one electrode (30) of the furnace. - The furnace power supply device (20) includes at least one power module (100), wherein the power module (100) includes: - A rectifier stage (110), which can be connected to a three-phase power grid (10), and - A converter stage (120) that can be connected to at least one electrode (30) of the electric furnace. - The furnace power supply unit (20) includes at least one DC bus (130) that connects the rectifier stage (110) of the at least one power module (100) to the converter stage (120). The furnace power supply device (20) is characterized in that it includes a cooling system (140).

2. The furnace power supply device (20) according to claim 1, characterized in that, The cooling system (140) includes a first cooling circuit (150) configured to direct cooling fluid to and away from the power module (100).

3. The furnace power supply device (20) according to claim 2, characterized in that, The cooling system (140) includes a first cooling fluid pump (153) configured to deliver the cooling fluid through the first cooling circuit (150).

4. The furnace power supply device (20) according to any one of claims 2 to 3, characterized in that, The cooling system (140) includes a filtration system (154), preferably a deionization system, which is configured to regulate and / or control the conductivity of the cooling fluid.

5. The furnace power supply device (20) according to any one of the preceding claims, characterized in that, The cooling system (140) includes at least one air conditioning system (180).

6. The furnace power supply device (20) according to any one of the preceding claims, characterized in that, The cooling system (140) includes a temperature and humidity control unit configured to regulate and / or control the temperature of the power module (100) and / or the humidity of the power module housing volume (102).

7. The furnace power supply device (20) according to any one of the preceding claims, characterized in that, The furnace power supply device (20) includes a power module housing (101), wherein the power module housing at least partially restricts the power module housing volume (102), and the power module (100) is arranged in the power module housing volume (102).

8. The furnace power supply device (20) according to claim 7, characterized in that, The power module housing (101) limits the amount of emission from the electromagnetic field.

9. The furnace power supply device (20) according to any one of the preceding claims, characterized in that, The furnace power supply device (20) includes at least one three-phase transformer, wherein each phase of the three-phase transformer includes a primary circuit and each phase includes one or more secondary circuits.

10. The furnace power supply device (20) according to any one of the preceding claims, characterized in that, The furnace power supply unit (20) includes an isolator, wherein the isolator is arranged between the converter stage (120) and the electric furnace.

11. The furnace power supply device (20) according to any one of the preceding claims, characterized in that: - The rectifier stage (110) of the power module (100) includes at least one three-phase rectifier circuit, and - At least one three-phase rectifier circuit of each power module (100) is connected to the DC bus (130).

12. The furnace power supply device (20) according to any one of the preceding claims, characterized in that, The furnace power supply device (20) includes multiple power modules (100) connected in parallel with each other.

13. The furnace power supply device (20) according to any one of the preceding claims, characterized in that, The furnace power supply device (20) includes at least two power modules (100), and - The converter stage (120) of each power module (100) includes at least two single-phase inverters, wherein each single-phase inverter is configured to supply power to a different phase of the electric furnace, and - The single-phase inverters configured to supply power to the same phase of the electric furnace are connected to the same DC bus (130).

14. The furnace power supply device (20) according to claim 13, characterized in that: - The furnace power supply device (20) includes at least two DC buses. - The single-phase inverter configured to supply power to the first phase of the electric furnace is connected to the first DC bus (130), and - The single-phase inverter configured to supply power to the second phase of the electric furnace is connected to the second DC bus (130).

15. An electric furnace comprising at least one furnace power supply device (20) according to any one of the preceding claims.

16. A production line for processing metal workpieces, the production line comprising at least one furnace power supply device (20) according to any one of claims 1 to 14 and at least one metal workpiece processing device.

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