DE102019008177A1 - HIGH-FREQUENCY MEDIUM VOLTAGE DRIVE SYSTEM FOR HIGH-SPEED MACHINE APPLICATIONS - Google Patents

Abstract

One aspect of the invention includes that a medium voltage power converter comprises a plurality of disks, each comprising: a transformer having a plurality of primary windings for coupling to a supply source for input power and a plurality of secondary windings; and a plurality of power cubes coupled to the plurality of secondary windings, each of the plurality of power cubes comprising a low frequency front end stage, a DC link, and a high frequency silicon carbide (SiC) inverter stage for coupling to a high frequency load or high speed machine.

Description

This invention was made with government support under the funding code DE-EE0007254 of the Ministry of Energy. The government has certain rights in the invention.

State of the art

Typical medium voltage (MV) power converters or so-called system drives or system converters (drive systems) are formed from silicon-based topologies. Such systems do not meet the high demands of various industries to improve overall system performance and costs. The special challenges for the systems include operation at higher fundamental frequencies than is currently possible, e.g. Up to 1000 hertz (Hz) for direct drive applications, high-performance MV drives to meet the power requirements in the medium power range (e.g. up to 20 megawatts (MW)), overall efficiency of the converter system better than 97% and reduced volumetric power density and footprint to improve system power density and costs. Current systems are not capable of such an operation.

Rather, traditional multi-megawatt and multi-level medium-voltage power converter technologies work on the basis of silicon components in the range of basic frequencies from 0-120Hz, circuits at 600 Hz and efficiencies of up to 95%. Operation at higher fundamental frequencies is prohibited due to high switching losses, which lead to steep system derating, dramatic system efficiencies and reductions in power density.

Object and solution of the invention

One aspect of the invention includes that a medium voltage power converter comprises a plurality of disks, each comprising: a transformer having a plurality of primary windings for coupling to a supply source for input power and having a plurality of secondary windings; and a plurality of power cubes connected to the plurality of secondary windings, each of the plurality of power cubes including a low frequency front end stage, a DC link, and a high frequency silicon carbide (SiC) inverter stage for coupling to a high frequency load or high speed machine.

In one embodiment, the medium voltage power converter further includes one or more sensors coupled to an input of the medium voltage power converter to obtain sensor information. The medium voltage power converter may further comprise a circuit breaker system connected between the supply source of the input power and the medium voltage power converter. The disconnector system can actively connect or disconnect the medium-voltage power converter based at least in part on the sensor information with the supply source of the input power. The medium voltage power converter may further include a network interface controller for storing and providing support functions for a high speed electrical machine coupled to a high speed mechanical load and a utility network. The high frequency load can be a high speed machine operating at a frequency between 500-1000 hertz with the input power supply source operating at a frequency of 50/60 hertz. The low-frequency front end stage can be an SiC-based active front end stage. Each of the plurality of power cubes includes a housing with a plurality of AC bus bars that are shifted toward a first surface of the power cube. A direct current bus (DC bus) of the direct current intermediate circuit can have a coated arrangement which is displaced toward a second surface of the power cube, the coated arrangement having a first horizontal section with gate driver openings (English: gate drive openings) that are formed directly through it. The DC bus may further include a second horizontal section that is vertically offset from the first horizontal section. The second horizontal section may be coupled to a plurality of capacitors, which may have a capacitance on the order of approximately 7.6-11.4 millifarads. The first horizontal section may include: a plurality of AC bus clearances through which a plurality of AC bus rails are to be connected to at least one SiC device; and a large number of gate driver interfaces via which connections for communicating gate driver signals are suitably set up.

Another aspect of the invention includes that a medium voltage power converter comprises: a plurality of disks, each having a transformer having a plurality of primary windings for connection to a common coupling point of a utility at a first frequency, and a plurality of secondary windings, each for coupling to one of a plurality of performance cubes of the disk, each of the plurality of performance cubes an active (IGBT) front end stage with insulated gate bipolar transistor (English: insulated gate bipolar transistor, IGBT), a DC intermediate circuit and an SiC back end stage for coupling to a load at a second frequency, wherein the second frequency is greater than the first frequency.

In one embodiment, if an energy source is present instead of a load, the SiC back output stage is to be operated as a rectifier and the active IGBT front output stage is to be operated as an inverter in order to enable current to be supplied to the provider via the common coupling point. The medium-voltage power converter can also include a controller which ensures that, when the supplier is the power source, the SiC back output stage functions as an inverter and the active IGBT front output stage functions as a rectifier.

Another aspect of the invention includes that a transformer for a medium voltage power converter comprises: a plurality of core legs that fit between a first pillar and a second pillar, each of the plurality of core legs having: a set of primary windings, which are appropriately arranged around the corresponding core leg; and a set of secondary windings suitably arranged around the set of primary windings.

In one embodiment, each of the plurality of core legs is associated with a phase of a three-phase power supply. The set of primary windings for a first core leg can be connected in parallel. In one embodiment, each of a first set of secondary windings that are arranged around the set of primary windings that fit around a first core leg is coupled to one of a first power cube, the first power cube being a low frequency front end , a DC intermediate circuit and a high-frequency back-end stage, a second power cube with a low-frequency front-end stage, a DC intermediate circuit and a high-frequency back-end stage, and a third power cube with a low-frequency front end stage, one DC intermediate circuit and a high-frequency back amplifier; each is made up of a second set of secondary windings that are fitted around the set of primary windings that fit around a second core leg, coupled to one of the first power cube, the second power cube, and the third power cube; and is each of a third set of secondary windings, which are arranged around the set of primary windings, which are arranged to fit around a third core leg, coupled to one of the first power cube, the second power cube and the third power cube.

In one embodiment, the plurality of secondary windings provide symmetrical impedance for the plurality of power cubes. Each of the set of primary windings may be spaced from another of the set of primary windings by a first separation distance of at least two inches to ensure decoupling from one another. The variety of secondary windings provides part of the symmetrical impedance for the variety of performance cubes to ensure tax stability. Each of the set of primary windings can be spaced from the set of secondary windings by a second separation distance of at least half an inch.

Another aspect of the invention includes that a medium voltage power converter includes a cabinet with: a power cube receptacle to accommodate a plurality of power cubes, each of the plurality of power cubes being fitted within a corresponding housing and a low frequency front end, a direct current Intermediate circuit and a high-frequency back-end stage, wherein the plurality of power cubes is provided for coupling to a high-speed machine; and a plurality of first barriers adapted to direct an isolated first flow of cooling air through one of the plurality of power cubes; and a transformer receptacle with at least one transformer for coupling between a supply connection and the plurality of power cubes, the transformer receptacle comprising a plurality of cooling fans for cooling the at least one transformer.

In one embodiment, the cabinet includes at least a first opening to divert the first cooling air flow from the transformer receptacle into the power cube receptacle and at least a second opening to direct an air flow emerging from the plurality of power cubes from the power cube receptacle into the transformer receptacle. The large number of cooling fans can extract the escaping air flow. The cabinet may include a permeable element to enable a second flow of cooling air from an external environment to be directed through the plurality of cooling fans through the at least one transformer. The cabinet can be designed as a sealed housing. In one example, the transformer receptacle is to be air-cooled and the power cube receptacle is liquid-cooled. The Power cubes can be isolated from the transformer.

In one embodiment, the power cube mount includes: a heat exchanger for extracting heat from the first cooling air stream; a first opening to allow the first flow of cooling air to pass through the plurality of power cubes; and a second opening for directing a flow of heated air from the plurality of power cubes to the heat exchanger.

Another aspect of the invention includes that a system includes one or more medium voltage power converters, each of which may include a first cabinet, comprising: a power cube receptacle for receiving a plurality of power cubes, each of the plurality of power cubes within a corresponding housing is fitted and comprises a low-frequency front end stage, a DC intermediate circuit and a high-frequency back end stage and the plurality of power cubes is provided for coupling to a high-speed machine; a transformer holder with at least one transformer for coupling between a supply connection and the plurality of power cubes. The transformer receptacle can include a plurality of cooling fans for cooling the at least one transformer. The at least one transformer may include: a plurality of core legs suitably arranged between a first column and a second column, wherein: a first core leg has a first plurality of cooling plates arranged there, one to fit around the first plurality of cooling plates an arranged first set of primary windings and a first set of secondary windings suitably arranged around the first set of primary windings; a second core leg has a second plurality of cooling plates suitably arranged there, a second set of primary windings suitably arranged around the second plurality of cooling plates, and a second set of secondary windings suitably arranged around the second set of primary windings; a third core leg comprises a third plurality of cooling plates suitably arranged there, a third set of primary windings suitably arranged around the third plurality of cooling plates, and a third set of secondary windings suitably arranged around the third set of primary windings.

In one embodiment, the system further includes: a first cooling plate that mates with at least a portion of the first column; and a second cooling plate matingly disposed on at least a portion of the second column. The first cabinet can be sealed with respect to an external environment, at least one first opening being provided between the transformer receptacle and the power cube receptacle in order to ensure a first cooling air flow from the transformer receptacle to the power cube receptacle, and at least a second opening between the transformer receptacle and the power cube receptacle is provided to ensure an exhaust air flow from the power cube holder to the transformer holder.

In one example, the system further includes a plurality of first barriers adapted to direct an isolated first flow of cooling air through one of the plurality of power cubes. The system may further include a first two-phase cooling system for cooling the at least one transformer via the first, second and third plurality of cooling plates and a second two-phase cooling system for cooling at least the low-frequency front end stage and the high-frequency back end stage of the plurality of power cubes include.

In a further embodiment, a device includes a cabinet with a medium-voltage power converter. The cabinet may include: a power cube receptacle for receiving a plurality of power cubes, each of the plurality of power cubes being fitted in a corresponding housing and comprising a front end stage, a DC intermediate circuit and a back end stage; a plurality of first barriers adapted to direct an isolated flow of cooling air through one of the plurality of power cubes; and a transformer receptacle with at least one transformer for coupling between a supply connection and the plurality of power cubes. The transformer receptacle may include: a plurality of cooling fans for directing the cooling air flow, the cabinet having at least one first opening for directing the cooling air flow from the transformer receptacle to the power cube receptacle, and at least a second opening for directing an air flow emerging from the plurality of power cubes from the power cubic receptacle for transformer mounting.

In one embodiment, the device further includes: a first plurality of cooling plates mating around a first core leg of the at least one transformer and disposed between the first core leg and a first set of primary windings mating around the first core leg; a second plurality of cooling plates, which are arranged to fit around a second core leg of the at least one transformer, and are arranged between the second core leg and a second set of primary windings suitably arranged around the second core leg; and a third plurality of cooling plates which are arranged to fit around a third core leg of the at least one transformer and are arranged between the third core leg and a third set of primary windings which are arranged to fit around the third core leg.

In one embodiment, the device may further include: a first cooling plate that mates with at least a portion of a first column of the at least one transformer; and a second cooling plate matingly disposed on at least a portion of a second column of the at least one transformer. The apparatus may further include a first two-phase cooling system for cooling the at least one transformer via the first, second and third plurality of cooling plates and a second two-phase cooling system for cooling at least the plurality of power cubes. The cabinet can be a sealed housing. The device may further include a plurality of choke coils fitted within the transformer receptacle, each of the plurality of choke coils connected between the at least one transformer and a corresponding one of the plurality of power cubes.

Figure list

• 1 10 is a schematic diagram of a high speed power converter environment according to an embodiment of the present invention.
• 2A 10 is a schematic diagram of a representative SiC-based modular power device according to an embodiment of the present invention.
• 2 B 10 is a schematic circuit diagram of a power cube according to an embodiment of the present invention.
• 2C 10 is a schematic diagram of a power cube according to another embodiment of the present invention.
• 3rd 10 is a schematic diagram of a modular multi-megawatt power converter system according to another embodiment of the present invention.
• 4th 10 is a block diagram of an interface circuit according to an embodiment of the present invention.
• 5 10 is a side view of a power converter cabinet according to an embodiment.
• 6 10 is a side view of a power converter cabinet according to another embodiment.
• 7 10 is a side view of a power converter cabinet according to another embodiment of the present invention.
• 8A 10 is a block diagram of details of a cooling arrangement for a transformer according to an embodiment of the present invention.
• 8B 10 is a rear view of a transformer further illustrating a cooling arrangement according to an embodiment of the present invention.
• 8C FIG. 10 is a cross-sectional view of a transformer column that further illustrates a cooling arrangement according to an embodiment of the present invention.
• 8D 10 is an illustration of a transformer according to an embodiment of the present invention.
• 8E 10 is a schematic diagram of transformer terminals according to an embodiment of the present invention.
• 9 10 is a graphical representation of a disc transformer efficiency curve according to an embodiment of the present invention.
• 10th 10 is a graphical representation of a disk assembly in accordance with another embodiment of the present invention.
• 11 10 is a graphical representation of an entire SiC-based performance cube according to one embodiment.
• 12 10 is a graphical representation of a DC bus arrangement according to an embodiment.
• 13 10 is an AC and DC bus decoupled arrangement according to one embodiment.

Detailed description

In various embodiments, a modular high-speed and high-frequency medium-voltage system converter can be implemented using a broadband gap (WBG) -based medium-voltage (MV) power converter. Such a power converter enables high-speed machine system converters. In some systems, a WBG-based MV Power converters and a high-speed induction machine are coupled together to enable bidirectional power transmission. The power transmission takes place between a supply network and a mechanical load. In further embodiments, the power converter system can be connected to an electrical or other high-speed load that can serve as a source, so that the system can transmit the collected energy with a suitable voltage and a suitable current to a supply network.

The system design can be used for highly efficient systems on complete WBG devices such as silicon carbide (SiC) metal oxide semiconductor field effect transistors (MOSFETs) or for cost-effective applications on active (IGBT) front end stages with bipolar transistor with insulated gate electrode gate bipolar transistor, IGBT), in which system derating is permissible and a minimum system power density and footprint are not restrictive. In another embodiment, a hybrid power topology (e.g., IGBT and SiC power MOSFET combinations) can be used - for easier electrical switching requirements or for cost reduction considerations while maintaining acceptable overall system performance.

In 1 a schematic diagram of a power converter environment according to an embodiment of the present invention is now shown. More specifically, as in 1 shown the power converter environment 100 implemented with a modular high-speed and high-frequency medium-voltage system converter with a hybrid converter arrangement in the manner described above. In the in 1 The embodiment shown is a system converter 115 via a point of common coupling (PCC) with a supply network (which can be operated with a frequency of 50 or 60 Hz depending on the country) through a disconnector system 105 connected. For example, the system converter is coupling 115 again to a high-speed machine 140 which in turn can be coupled to a high speed mechanical load.

The system converter 115 can be implemented in one or more cabinets. In one embodiment, the system converter 115 as 1.8 - 2.3 MVA high-frequency converters with a nominal voltage of 4160 volts (V) and operable between 500-1000 Hertz (Hz). As shown, the system converter can 115 a multi-slice arrangement with a single network control, where a converter system control is arranged, and 3 slices, which act as a subsystem 120 are included. In the overview view in 1 it should be noted that the subsystem 120 consists of disks with hybrid technology, namely front ends consisting of IGBTs and back ends consisting of SiCs - which results in a hybrid topology. As used here, the term “slice” refers to a portion of a power converter system that includes at least one transformer and several so-called power cubes that include semiconductor switching devices. A slice-based system thus couples between a network connection that can operate at a first, low frequency and a load connection that can operate at a second, high frequency. And as described here, the direction of power flow through a disk can be bidirectional depending on the given system implementation and control configuration. It should be noted that the term “low frequency” as used here refers to a frequency of a supplier - generally less than 100 Hz and in particular 50 or 60 Hz. And the term “high frequency” is used as used here operate at a frequency that is significantly greater than the supply frequency. Representative applications of a power converter can, for example, be coupled to high-frequency loads between approx. 500 Hz - 1000 Hz.

Although in 1 Represented as a hybrid topology, it should be understood that a complete WBG-based topology can be present in other implementations. With associated electronics, this arrangement of the system converter 115 also referred to here as a modular power building block (MPBB). Details of a specific MPBB and a disk are described in more detail below. As shown, the subsystem couples 120 between an input from the supply network via a vacuum contactor VC1 and protection by means of transient voltage suppression (TVS) Dl. In return, an output of the subsystem couples 120 via a 3-phase, simply shielded power cable 129 to another housing 140 in which there is an electrical machine 145 located.

With regard to the further details shown in the figure in 1 system converter 115 an external cooling unit 123 that have an optical fiber connection with the subsystem 120 connected is. In addition, a high voltage feedback board (HVF) 122 between the input of the subsystem 120 and its output switched. HVF 122 continues to couple to a main system control board (MSCB) 124 , which in turn is connected to a programmable logic controller (PLC) of the system 126 is coupled. As shown, the system PLC couples 126 to a fiber to RS232 converter 128 to provide a fiber interface. In addition, HVF couples 122 to a recipient 125 . The communication blocks 128 and 125 offer a fiber-optic implementation to minimize the effects of latency and noise on local command communication signals between the speed system inverter 115 with variable frequency and the high-speed machine 140 . The control panel MSCB 124 processes the control signal from HVF 122 , System PLC 126 and receiver 125 . The control panel MSCB 124 transfers the generated actions via the system PLC 126 to the rest of the system and voltage command references to the subsystem 120 for space vector pulse width modulation (SVPWM) and the implementations of spread carrier PWM switch modulation.

Continue with reference to 1 are also details of the high speed machine 140 shown. As illustrated, the high speed machine 140 be designed in one embodiment for a nominal power of 4160 V and 15,000 rpm or for other nominal powers of higher voltage and speed. The high-speed machine 140 includes an electrical machine 145 using a shielded power cord 129 3-phase current receives. Measurements related to the parameters of the electrical machine 145 can be performed by various components, including the RTDs 143 , whose outputs via a fiber optic connection via an RTD fiber converter 142 , Acceleration sensors 152 , Proximity switch 154 and a phase position sensor (key phasor) 156 can be sent. As shown, these components can be controlled by a controller, namely a network interface controller 160 , are connected to the system PLC via fiber optic interfaces 126 of the system converter 115 is coupled. In a preferred embodiment, the network interface controller is located 160 within the MPBB 115 and offers advanced support functions for the high-speed machine 140 , a controller for high speed mechanical loads 165 (English: high speed mechanical load controller) and a network system manager 170 . In addition, the network interface control offers 160 Local smart capability by storing and processing connection information, such as advanced support function algorithms.

As can be seen further, the high speed machine includes 140 also a power supply 141 which can be configured as a 120 VAC / 24 VDC power supply, which in turn is a transmitter 144 (English: transmitter) and an encoder 146 (English: encoder) supplied, which can be coupled to a mechanical load. In 1 the embodiment is shown in an overview view and it should be understood that many variants and alternatives are possible.

In 2A is a schematic circuit diagram of a representative SiC-based modular power module (MPBB) 200 shown. In typical versions, the modularity can be guaranteed by a system converter with several MPBBs. For better illustration, however, is in 2A only one MPBB shown. In the embodiments, the MPBB 200 be carried out in one or more modular housings, for example in a series of cabinet housings. Regarding MPBB 200 are a variety of discs 225 ₁ -225 ₃ available. In one example of a modular implementation, each slice can 225 can be implemented in a separate window cabinet. Although to simplify the illustration in 2nd is not shown in this way, it is to be understood that an MPBB can also contain a further cabinet for accommodating a network control and the associated electronic circuits, as in the overview view of the 1 shown.

As you can see, each disc contains 225 a transformer 230 ₁ -230 ₃ . Each transformer is a 3-phase transformer that can have a primary side configured in a WYE configuration and a secondary side configured in a DELTA configuration. More specifically, each transformer includes 230 a large number of transformer legs (three legs per transformer) that can be fitted between a pair of columns of the transformer. Each transformer leg has a 3 WYE input winding configuration that is connected in parallel at the input (WYE equivalent) and a 3 isolated DELTA winding configuration at the output. For the three transformers 230 ₁ -230 ₃ all 9 WYE primary configurations at the input (GRID) are connected in parallel. As shown, the secondary windings of the transformers couple 230 again to corresponding performance cubes 240 _A1 -240 _C3 . As used herein, the term "power cube" refers to an electronic module that includes semiconductor devices that receive switching signals to perform rectification and inverter operations to process a current flow, including converting an incoming power at a first frequency to an outgoing, processed one Power with a second frequency. Depending on the direction of the power flow, the first frequency can be higher than the second frequency or vice versa.

In the overview view in 2A and as especially in the schematic in 2 B shown, in one implementation each of a plurality of power cubes 240 _{1, ac} - 240 _{3, ac is} implemented as a full SiC power cube with an active front end (AFE) converter 242 , which is made up of a variety of SiC switching devices, a DC bus with a capacitance C1 is implemented, and an H-bridge converter stage 244 , which is implemented with another variety of SiC switching devices. It should be noted that the component 242 a rectifier and the component 244 is an inverter when the power in the block diagram in 2 B flows from left to right. If the power flows from right to left, the component is working 242 as an inverter and the component 244 as a rectifier. AFE means that the level is actively controlled. In this embodiment, the switching frequency of the SiC devices is set between 4 and 12 kHz, but depending on the various operating requirements (e.g. 2-phase cooling plate temperature resistance limit) and the desired performance goals (e.g. control stability of the DC bus control), other switching frequencies be used. For example, in the production plant (from right to left on the power cube 240 ) the specified active power is recorded on the single-phase AC side at 740VAC and by the power converter stage 244 processed according to a PWM control scheme. This power is through the capacitor bank C1 the DC intermediate circuit by the power stage 242 regulated to 1000VDC using a SVPWM control scheme, transmitted and delivered on the 3-phase AC side at 600V. The collected system power energy is through the disconnector system 105 transferred to the power grid by on the network interface control 160 implemented tax actions is controlled. During engine operation, the active power flows from left to right according to the opposite control process described above. During this mode, the high speed machine system can 140 using one on the MSCB 124 implemented speed control algorithm can be controlled.

In execution in 2C an alternative embodiment of a performance cube is shown schematically. Here is the performance cube 240 ' implemented with a hybrid topology that is a front end 246 from IGBTs, one by one capacity C1 represented DC bus and a back-end stage 248 with SiCs. As with the discussion above, depending on the direction of the power flow, either the front power amplifier 246 or the back amplifier 248 act as an inverter or rectifier. In this embodiment, the front-end switching frequency is set between 2 kHz and 6 kHz and the back-end switching frequency between 6 kHz and 12 kHz, but other switching frequencies can be used depending on the operating requirements and desired performance goals. The main advantage of the performance topology of the performance cube 240 ' can be an inexpensive system implementation. The back amplifier 248 can use SiC-based devices (e.g. 1700V SiC power MOSFETS) and the front end stage 246 can be implemented with inexpensive Si-based devices (e.g. 1700V IGBTs).

In 3rd a schematic representation of a system according to a further embodiment of the present invention is now shown. As in 3rd shown is the system 300 as a multi-megawatt scale power converter system 310 executed. More specifically, is the representative power converter 310 as a scalable, fully SiC-based multi-megawatt power converter with a variety of modular drive housings 315 ₁ -315 _n or SiC-MPBBs, each with a multi-disc system converter 320 ₁ -320 _n include. Every MPBB 315 includes a multi-disc system converter 320 and a network cabinet (system control, output / input sensors, input / output AC connections). The number of MPBBs that form a specific power converter depends on the design and depends on the power requirement.

As shown, the power converter is 310 with a net 302 connected, which can supply 3-phase electricity with 13.8 kilovolts (kV). As seen, the power converter couples 310 via a PCC to the network 302 . The power converter 310 in turn, can couple to various loads, including a high speed electrical machine 340 that can be coupled to a high speed mechanical load or other electrical machine system (not shown). As illustrated in the illustrated embodiment, any power converter can 310 Output 3-phase current with 4.16 kV at a certain frequency (e.g. between 500-1000 Hz) or a higher nominal voltage for other high-speed machine systems.

Regarding the representative power conversion system 310 the incoming power is via a disconnector system 305 to an input of a certain drive housing 315 provided. In an exemplary embodiment, this input power may be provided at 74 amps (A). And in one embodiment, each MPBB 315 , which includes a set of disks, provide output power at 350A. In the in 3rd Each MPBB can display the overview view 315 , at an entrance to the windows as in above 1 described components, including vacuum contactor, TSV diode include.

As further illustrated, the sensors can 312 _1A and 312 _1B be provided at the entrance and exit of the panes. In one embodiment, such sensors may include 100A and 500 LEM sensors for 13.8kV / 4.16kV MPBB systems to provide information about the operation of the panes and to implement system protection and network connection. In particular, the disconnector system coupled on the network side 305 , based on sensor data, system-controlled to respond to converter commands to the power converter 310 during normal system operation or in the event of system error events with the network 302 to be connected or not to be connected. It should be noted that in embodiments sensors like the sensors 312 as shown, can be local or remote to provide information such as voltage, current and frequency from the power grid.

In this way, a system converter consisting of one or more MPBBs can couple between a mains connection and a high-frequency load. For example, the input of the MPBBs can be connected to a mains connection that works with 3-phase at 60 Hz, 13.8 kV, and the output of the MPBBs supplies output power for a high-frequency load, e.g. can be operated at 500 Hz, 4.16 kV and 3-phase. Conversely, the MPBB can use a high-frequency generator, e.g. works at 500 Hz, 4.16 kV 3-phase, connect to a 3-phase mains connection at 60 Hz, 13.8 kV.

In one embodiment, a fiber optic SiC gate driver interface can be implemented to improve immunity to system noise and enable local control signal management. It can be adapted to any commercial or customized dual SiC-based device solution. In one embodiment, the interface can be suitably arranged on a circuit board, which can be arranged directly above a gate driver of the device, in order to minimize the inductive coupling during the signal connection. An FPGA chip can be used onboard to implement locally smart functions to improve the performance of SiC components and to simplify the placement within this unit. The interference of control and status signals between the controller and half-bridge gate drivers due to high electrical noise environments in SiC systems can be reduced. A simplex fiber line can be used to transfer the switching states of the half-bridge and the control of the gate driver board from the controller to the gate driver. A simplex fiber line can be used to transmit fault conditions and SiC-MOSFET temperature from the half-bridge gate driver to the controller. An isolated power supply can be used for each half-bridge driver to minimize ground loops between the individual half-bridge controllers.

In 4th a block diagram of an interface circuit according to an embodiment of the present invention is now shown. More specifically, as in 4th shown, the interface circuit 400 can be implemented with a fiber optic SiC gate driver interface to control the various switching components of a wafer as described here.

As shown, the interface circuitry includes 400 a cube control 410 which can generate various control and switching signals, for example based on feedback status information and control information which is provided by a higher-level controller (for example a disk controller which is used in 4th is not shown for better illustration) are received. The cube control 410 is shown to have a variety of interfaces 420 ₁ -420 _n connected is. How to look at the representative interface 420 ₁ can see is a DC / DC power supply 425 included, which is a gate drive fiber interface (GDFI) fiber interface control 430 powered, which in turn is coupled to a general SiC gate driver 435. Such a gate driver can in turn be used with a half-bridge SiC or IGBT module 440 get connected. It should be noted that SiCs / IGBTs themselves at an interface 420 are not available and that, as described in more detail below, they are connected under the interface card and directly on a cooling plate. As shown, the cube control 410 optically different information via fiber optic, including the gate state and the control signals, with the controller 430 communicate. IGBT and drive status can also be sent to the cube controller via fiber optic communication 410 are reported back (these bidirectional signals are common as signals 450 shown). To the communication between the controller 430 and the gate driver 435 copper connections can be used to ensure.

Although the embodiments are not limited in this regard, the use of fiber optic communication allows a distance of approximately 0.1-50 meters between cube control 410 and interface control 430 will be realized. With the copper connection between the interface controls 430 and the gate drivers 435 a relatively small distance can be maintained (e.g. 1.5 inches).

Embodiments can enable cooling of transformers and inverters in different ways. In some cases, both sections, as implemented in a particular pane cabinet, can be air cooled. And one or more of the transformer and inverter sections can be liquid cooled via a two-phase cooling system.

In various embodiments, cooling assemblies for power transformers can provide improved heat dissipation. Transformers and power cubes can be cooled using through-air to improve heat dissipation (using mechanical barriers). Regardless of whether the overall cooling is air or liquid cooling, it should be understood that the power cube cooling of main semiconductor components (e.g. all SiCs and IGBTs) can be carried out internally with the help of 2-phase cooling.

In 5 a side view of a power converter cabinet according to an embodiment is shown. Note that the closet 500 is a disk cabinet (with a single transformer and 3 power cubes). It is to be understood that, as in 2nd defines, in one embodiment, an MPBB 3rd Cupboards are manufactured comprehensively. As in the cross-sectional view in 5 shown, includes the closet 500 a transformer section 510 and an inverter section 550 . As shown, the transformer section includes 510 a transformer 515 with several transformer legs 515 ₁ -515 ₃ . With this design, the incoming air can flow through a grille or another permeable element on a front part of the cabinet 500 be included. As you can see, the incoming air flow is controlled by a variety of cooling fans 520 ₁ -520 ₃ through the transformer legs 515 passed the exhaust air through the back of the cabinet 500 conduct. A mechanical barrier for separating cube and transformer sections can be implemented as a horizontal barrier made of GPO-3 polyester material. As shown, this barrier has openings 568 and 570 .

In turn, additional air from the transformer section 510 to the inverter section 550 through one or more openings 568 headed through a variety of performance cubes 560 ₁ -560 ₃ flows. It should be noted that in embodiments, mechanical barriers 565 ₀ -565 ₃ , for example made of GPO-3 polyester material, the air flow for correct cooling of the system from the opening 568 through the performance cube 560 ₁ -560 ₃ to force. In this way, each power cube receives a supply of fresh air for cooling, which is then on the back of the cubes 560 and down through one or more openings 570 back to the transformer section 510 is vented. These mechanisms ensure air circulation, taking the air through blowers 520 is directed outside. So get the transformer legs 515 and the performance dice 560 Fresh air from outside and the air is expelled at the back of the cabinet.

In 6 a side view diagram of a power converter cabinet according to another embodiment is now shown. As in the cross-sectional view in 6 shown, includes the closet 600 a transformer section 610 and an inverter section 650 . As shown, the transformer has 615 several transformer legs 615 ₁ -615 ₃ on. In this version, the supply air can be supplied via a grille on a front part of the cabinet 600 be included. As can be seen, the incoming air flow is controlled by a variety of cooling fans 620 ₁ -620 ₃ through the transformer legs 615 passed the exhaust air through the back of the cabinet 600 conduct. As in 6 shown, the transformer section 610 be air cooled in the same manner as above in relation to 5 discussed. In contrast to the embodiment in 5 offers 6 however, an arrangement in which the inverter section 650 is liquid cooled. Thus, the inverter section 650 against the transformer section 610 remain sealed so that there is no air exchange with the transformer section 610 takes place.

As further shown, the cooling for the inverter section 650 over a cooling section 680 take place, a flow of liquid coolant for the inverter section 650 by using 2-phase cooling in a sealed manner. To improve the heat dissipation of the power cube, the 2-phase liquid can circulate through a heat exchanger that is external to the cabinet 600 connected is. With those in the inverter section 650 provided cooling fans 670 the air can pass through the entire inverter section 650 circulate back. In some embodiments, liquid cooling capability may be implemented within the inverter section 650 an expanded cabinet with a bumpout section may be provided. The barriers 665 ₀ - 665 ₃ conduct the cooling air flow of the cooling fans 670 continue through the performance dice 660 ₁ - 660 ₃ .

In yet another embodiment, both transformer and power cubes are as shown in 7 shown, 2-phase liquid-cooled to maximize the heat dissipation of the panes. In 7 10 is a side view of a power converter cabinet according to another embodiment shown. As in the cross-sectional view in 7 shown, includes the closet 700 a transformer section 710 and an inverter section 750 . As shown, includes a transformer 715 several transformer legs 715 ₁ -715 ₃ . Note that the closet 700 is sealed against the outside air, but an air exchange between the transformer section 710 and the inverter section 750 over the openings 768 and 770 takes place. In one embodiment is a heat exchanger 790 between the transformer section 710 and the internal fans 720 installed to maintain air circulation through the transformer coils and power cubes. In addition to the heat exchanger 790 one or more cooling plates can also be arranged directly on the transformer cores. So, as in 7 shown the cooling plates 796 , 798 on the front and rear parts of the transformer 715 be arranged. As in the overview view in 7 shown, the heat exchanger 790 Coolant connections 792 , 794 involve a flow of coolant through the heat exchanger 790 to lead. Similar cooling of the inverter section 750 by directing the cooled air over the opening 770 is provided enables the cooling of corresponding power cubes 760 , the heated air through the opening 768 to the transformer section 710 flows back. The barriers 765 ₀ - 765 ₃ conduct the cooling air flow of the cooling fans 720 continue through the performance cube 760 .

In still further embodiments, the additional cooling of a transformer can be implemented by providing cold plates on the surfaces of the cores of the transformer. In one embodiment, between 2 and 4 cold plates with a width of, for example, 6 inches can be assigned to each core leg. In order to improve the heat transfer of the transformer cores, additional cold plates, which are arranged on the columns of the transformer, can be located on the front and rear of the transformer. So in the illustration in 8A Details of a cooling arrangement for transformers are shown. In a side view 810 in 8A are the transformer legs 815 ₁ -815 ₃ shown. The cold plates 820 are on the front and back of the transformer columns 811 , 812 suitably arranged, the connections 822 , 824 for directing a flow of liquid coolant. In addition, a variety of cold plates 840 ₁ -840 ₆ available. As can be seen, any cold plate can 840 can be installed above and below the core leg and each can have a corresponding coolant connection 842 include to ensure a flow of liquid coolant. As in 8A further illustrated, insulation and air ducts may exist between different transformer windings and cold plates.

Still referring to 8A is an arrangement of the windings of the transformer 815 shown. More specifically, the transformer includes 815 a separate winding structure in which several separate windings, both primary and secondary, for each transformer leg 815 are provided. In the in 8A The view shown is three separate primary windings 816 ₁ -816 ₃ for the transformer leg 815 ₁ shown. And right around each of the primary windings 816 is accordingly one of several secondary windings 818 ₁ -818 ₃ wrapped. Further details on this winding arrangement arranged side by side or separately are described below.

8B and 8C also show layouts for liquid cooling. In particular shows 8B a rear view of a transformer 815 , a cold plate in the back of the transformer 820 is arranged. It should be noted that a corresponding cold plate can also be installed on the front of the transformer. The coolant connections are also shown 822 , 824 . And 8C shows a cross-sectional view of a transformer column, the cold plates, on respective sides of the core leg 815 can be arranged appropriately, further illustrated. It should be noted that a cold plate with a generally rectangular or square cross section of the core legs 815 can be arranged substantially flat or flush with a specific surface of a core leg. So, as in 8C shown, each core leg 815 additional corresponding cold plates 845 feature that are adjusted on their sides.

In 8D an illustration of a transformer according to an embodiment is now shown. More specifically, is in 8D an electrical arrangement of the transformer 815 shown without cooling structures in order not to hide details of the segmented winding arrangement. As shown, the transformer is 815 with a variety of core legs 815a-815c trained, each between a first pillar 811 and a second pillar 813 are coupled. In one embodiment, the core legs 815 and the pillars 811 , 812 be made of iron. In the detailed arrangement of the first core leg 815a which can correspond to a first phase (phase A) are a large number of primary windings 816 _{a, 1} - 816 _{a, 3} with a segmented winding structure present around the core leg 815a are wrapped. It should be noted that in the case of a cooling arrangement such as this, cooling plates can of course be arranged between the core leg and these primary windings.

And as further illustrated, the corresponding secondary windings are 818 _{a, 1} - 818 _{a, 3} wrapped directly around the corresponding primary windings. The separation between primary windings and secondary windings determines the equivalent inductance per phase on the secondary side of the transformer 815 . The recommended value of the leakage inductance to support the control stability of each AFE power level is achieved by a minimum distance between the windings. In other words, there may be a corresponding minimum distance between the wound primary and secondary windings. For example, there may be a distance of at least half an inch between a primary winding 816 and a corresponding secondary winding 818 consist.

In one embodiment, a corresponding separation distance 813 , 817 be provided between the segmented winding sets. By providing these segmented winding sets and the corresponding separation distances, symmetrical secondary impedances can be realized. The impedance-balanced effect per phase is achieved by creating a decoupling magnetic effect between the winding sets 816 and 818 reached. This magnetic effect is achieved by setting a minimum horizontal distance of two inches between adjacent winding sets 816 and 818 realized. It should be noted that for the transformer legs 815b , c of the second and third phases (which in 8D are shown in a restricted form) corresponding sets of primary and secondary windings 816 _{b, 1-3} , 818 _{b, 1-3} and 816 _{c, 1-3} , 818 _{c, 1-3} are provided.

In 8E is now a schematic diagram showing the segmented windings in 8D correlated with the corresponding connections each of a plurality of power cubes of a given slice. As shown, the corresponding primary windings of a particular transformer leg (namely, the same phase) couple to a same phase of the input power. In the same way, the corresponding secondary windings of a specific phase limb in a DELTA configuration link to one of the corresponding power cubes (not shown in 8E shown) of a particular disc. It should be noted that in FIGS. 8D and 8E the additional reference marks for the primary and secondary windings, as they are arranged around a transformer leg and in the circuit diagram in 8E _[FvS1] showing correspondences between primary and secondary windings for a first phase (AP1-AP3 and AS1-AS3). Thus, with an arrangement as in 8E a transformer adapted for three parallel WYE configurations on the primary windings and three isolated DELTA configurations on the secondary side of the transformer.

Thus, embodiments of this arrangement offer a highly efficient power transformer design with symmetrical secondary impedances. There are three parallel primary windings for each secondary winding. The arrangement of the windings next to each other reduces the coupling between the secondary windings and also increases the equivalent impedance effective for the converter. This eliminates the need for an additional series inductance per phase, which is used on the primary or secondary side of the transformer, to ensure the stability of the converter control. In addition, there are no additional filters at the converter input. For Si-based device systems, the need for additional inductance may be permissible because the converter's AFE is switched at low frequency to keep the total loss low. The transformer is designed so that it can be operated at points A and B, like the efficiency curve in 9 shows. In one embodiment, the transformer power is in the range of 750 kVA and 1000 kVA for a disk system configuration. With symmetrical impedances, the windings are wound side by side.

In 10th a block diagram of a disk arrangement according to a further embodiment of the present invention is now shown. In particular, in the embodiment in 10th a disc further provided with an additional inductance for active front-end devices by means of choke coils. As in 10th shown, includes a disk cabinet 1000 a transformer section 1010 and an inverter section 1050 . In the illustration shown, an arrangement with air-cooled transformer and inverter sections is provided. In addition (and for comparison to that in 5 arrangement shown) are within the transformer section 1010 a large number of AFE choke coils 1040 ₁ -1040 _{3 are} provided. With these AFE choke coils, a structure is implemented that enables an additional inductance for Si-based designs. The required inductance can be in the range of 5% and the switching frequency is kept in the range of 2-3 kHz. The AFE choke coils are connected in series (per phase) between each secondary DELTA and the corresponding cube AFE converter input line.

Embodiments can also enable efficiency increases in the configuration of a power cube for implementing SiC-based switching devices. In particular, in one embodiment, a coated DC bus bar design can be used to improve the performance of WBG devices. This design can use parasitic inductance to improve the switching performance of SiC devices to less minimize than 13nH. The design improves cube switching and short circuit protection by minimizing the total equivalent loop inductance when switching SiC devices. In a preferred implementation, a complete SiC device topology with a specific SiC power module terminal layout can be used.

In a further implementation, a cube topology for hybrid devices (e.g. Si IGBT-based rectifier and SiC MOSFET-based inverter) can be used, which uses the same concept to minimize the inductance of the DC link. This should be understood to mean that other SiC device packages with different power terminal layouts can also be used.

In 11 A graphical representation of a complete SiC-based performance cube is shown according to an embodiment. As you can see, the performance cube is 1100 in one housing 1110 implemented. The incoming 3-phase power received from a transformer secondary is routed through a variety of input AC bus bars 1180 provided. In one embodiment, three such input bus rails are provided to couple incoming 3-phase power with corresponding front-end SiCs. As in 11 shown are the AC bus rails 1180 towards a back section of the performance cube 1100 moved to improve heat dissipation. This is because with this placement the AC bus rails 1180 the busbar design is simplified by making them shorter in length and the majority of their heat dissipation not concentrated above the SiC devices or below a DC busbar. So in the illustrated embodiment, the bus rails 1180 can be coupled with SiCs of a front power amplifier (details on this can be found in 11 not shown). It should be noted that the switching of the SiC devices via the glass fiber SiC gate driver interfaces 1120 ₀ -1120 _n can be controlled. While 5 such driver interfaces in the embodiment in FIG 11 are shown, other numbers may be present in further embodiments. For non-regenerative applications, a passive front-end rectifier can include two-diode power modules, so that only two switches are controlled (inverter side) and therefore only two driver interfaces are used. Hybrid and full SiC topologies each use 5 controlled switches (SiC-MOSFET and / or IGBTs), which is why 5 driver interfaces are required. A maximum of 10 driver interfaces may be required for parallel SiC devices. Control signals are the driver interfaces 1120 via a SiC-based control board 1130 provided that over appropriate fiber optic connections 1135 with the interfaces 1120 is connected. As in 11 further illustrated are the driver interfaces 1120 arranged above the SiC modules themselves, which in turn are on a cooling plate assembly 1150 are arranged. It should be noted that the power supply of various control and monitoring circuits via a power supply 1195 can be done.

As further shown, is on a front portion of the housing 1110 a DC intermediate circuit with a DC bus 1160 formed, details of which are described below. The DC intermediate circuit also includes the DC bus 1160 even a variety of capacitors connected to it 1165 , one of which is in 11 is marked representative. In one embodiment, the performance die 1100 with a DC bus 1160 be implemented with the capacitors 1165 that are optimally dimensioned. In a particular embodiment, a particular power cube can be implemented for better transient and power transfer performance with a capacitance of approximately 7.6-11.4 millifarads (mF).

Still referring to 11 can the output power from the power cube 1100 over a variety of output bus rails 1170 are output, as shown, with appropriate AC bus rails 1180 couple.

To cool SiCs and other components within the performance cube 1100 to ensure the lines 1190 , 1192 be provided to direct a flow of coolant or other coolant. 11 shows the embodiment in an overview view and it should be understood that many variants and alternatives are possible.

Embodiments provide a DC bus design that improves SiC device spacing. In particular, a DC bus can be designed to mechanically decouple the DC bus from the AC bus rails; this can further simplify the construction of AC bus rails as described above. In this way, the connector spacing of the devices can be increased (e.g. from 2 mils to 5 mils). And with an improvement in electrical isolation, in an exemplary embodiment, the DC intermediate circuit can operate at between 1000-1200VDC.

In 12 a graphical representation of a DC bus arrangement according to an embodiment is now shown. As in 12 shown, the DC bus 1200 over a coated structure of a variety of layers 1210 ₀ -1210 _n includes to be implemented. In the specific embodiment shown, a five-layer arrangement is realized, although in certain embodiments there may be more or fewer layers. As shown, the DC bus is 1200 made with alternating layers of conductive and insulating material. More specifically, the negative and positive DC bus layers couple 1210 ₁ respectively. 1210 ₃ between the corresponding insulation layers 1210 ₀ , 1210 ₂ and 1210 _n . In one embodiment, the DC bus layers 1210 ₁ , 1210 ₃ using a given conductive material, such as copper, and can have an approximate thickness of 50-100 mils. The insulating layers 1210 ₀ , 1210 ₂ , 1210 _n in turn can be carried out with an insulating material, for example insulating PET materials. In a particular embodiment, the insulation layers 1210 ₀ , 1210 _n with a thickness between about 5-10 mils and the insulation layer 1210 ₂ be formed with an insulating material from a layer between 5-20 mils thick.

How also on the job 1250 in 12 is shown with the raised arrangement of the DC bus 1200 that consists of a first horizontal section 1275 and a second raised horizontal section 1280 there is a mechanical decoupling of AC bus rails from the intermediate circuit. As also shown, the designed DC bus has a plurality of recesses, including the representative recesses 1260 and 1270 on the first horizontal section 1275 . More specifically, the recesses ensure 1260 a recess for AC buses. About the recess 1260 an AC bus bar can be screwed to an SiC device. The second horizontal section 1280 in turn, can provide a connection to the capacitors of the DC intermediate circuit.

About the recesses 1270 gate driver connections can be made. About this position of the recesses 1270 can maximize the copper area of the DC bus and simplify the design of the AC bus bar. This means that the AC bus bars can be arranged straight from the rear of the power converter. This enables a reduction in copper (smaller AC buses) and simplification of housing (smaller dimensions). In one embodiment, the positive and negative SiC device connection to the coated DC bus is accomplished by three punched circles on either side of the recesses 1260 are arranged. In contrast to groups of punched circles, other openings for SiC device connector shapes can be used to improve the creepage distances of DC bus connectors. With this coated arrangement, the first horizontal section 1275 With gate driver openings included directly through the DC bus, the decoupling of AC bus rails and DC bus rails is made possible.

In another system construction (not shown), the insulation around the SiC device connectors is maximized by the recesses 1270 and 1260 into a single opening on an insulation layer to increase the spacing to over 5 mils without significantly increasing the loop inductance of the system. The same procedure can also be used on the negative copper plate 12103 be performed.

In 13 an arrangement with decoupled AC and DC buses is shown. More specifically, as in 13 shown an arrangement of the cooling plates 1300 provided on the a variety of gate driver interfaces 1310 ₀ -1310 _n available. As discussed above, such driver interfaces provide control signals for gates of SiCs or other switching devices 1330 that fit beneath the gate driver boards (and that with the cooling plate assembly 1300 are coupled). As further illustrated, are next to the switchgear 1330 a variety of AC bus rails 1320 ₀ -1320 _n available. While 5 such AC bus bars are shown, more or less may be present in certain embodiments. With this arrangement, the AC bus rails can 1320 be decoupled from a DC bus (not in 13 shown), but it is to be understood that such a direct current bus on a rear side of the cooling plate arrangement 1300 is arranged (while the AC bus rails 1320 from a front portion of the cooling plate assembly 1300 extend from). In this way, the AC bus rails offer 1320 an improved accommodation of the performance cubes. It should be noted that output bus bar cube connections (not in 13 shown) with AC bus rails 1320 ₃ , 1324 _n , can be connected.

While the present invention has been described with reference to a limited number of embodiments, those skilled in the art will recognize numerous modifications and variations therefrom. The appended claims are intended to cover all changes and variations that come within the basic idea and scope of this present invention.

Claims (43)

Medium voltage power converter, comprising: a variety of slices, each having: a transformer comprising a plurality of primary windings for coupling to a supply source of an input power and a plurality of secondary windings; and a plurality of power cubes connected to the plurality of secondary windings, each of the plurality of power cubes having a low frequency front end stage, a DC link, and a high frequency silicon carbide (SiC) inverter stage for coupling to a high frequency load or a high speed machine. Medium voltage power converter after Claim 1 , further comprising one or more sensors coupled to an input of the medium voltage power converter to obtain sensor information. Medium voltage power converter after Claim 2 , further comprising a circuit breaker system which is connected between the supply source of the input power and the medium voltage power converter. Medium voltage power converter after Claim 3 , wherein the circuit breaker system is to at least partially connect or disconnect the medium voltage power converter based on the sensor information with the supply source of the input power. Medium voltage power converter after Claim 1 , further comprising a network interface controller for storing and providing support functions for the high-speed machine, a mechanical high-speed load and a supply network system. Medium voltage power converter after Claim 1 , wherein the high frequency load comprises a high speed machine operating at a frequency between 500-1000 hertz, the supply source of the input power operating at a frequency of 50/60 hertz. Medium voltage power converter after Claim 6 , wherein the low-frequency front end stage comprises an SiC-based active front end stage. Medium voltage power converter after Claim 1 wherein each of the plurality of power cubes includes a housing with a plurality of AC bus bars that are shifted toward a first surface of the power cube. Medium voltage power converter after Claim 8 , wherein a direct current bus (DC bus) of the direct current intermediate circuit comprises a coated arrangement which is displaced towards a second surface of the power cube, the coated arrangement having a first horizontal section with gate driver openings, that are trained right through there. Medium voltage power converter after Claim 9 wherein the DC bus further includes a second horizontal portion vertically offset from the first horizontal portion to couple to a plurality of capacitors, the plurality of capacitors having a capacitance between about 7.6 and 11.4 millifarads. Medium voltage power converter after Claim 10 , wherein the second horizontal section is provided for coupling to a plurality of capacitors. Medium voltage power converter after Claim 11 , wherein the first horizontal portion comprises: a plurality of AC bus recesses through which a plurality of AC bus rails are to be coupled to at least one SiC device; and a plurality of gate driver interfaces via which connections for communicating gate driver signals are suitably set up. Medium voltage power converter, comprising: a plurality of disks, each having a transformer that a plurality of primary windings for connection to a common coupling point of a supplier at a first frequency and has a multiplicity of secondary windings, each for coupling to one of the multiplicity of power cubes of the disk, each of the multiplicity of power cubes having an active (IGBT) front end stage with a bipolar transistor with an insulated gate electrode (insulated gate bipolar transistor), a direct current intermediate circuit and a silicon carbide (SiC) back stage for coupling to a load at a second frequency, the second frequency being greater than the first frequency. Medium voltage power converter after Claim 13 , where, if the load is an energy source, the SiC back output stage is to be operated as a rectifier and the active IGBT front output stage is to be operated as an inverter in order to enable current to be supplied to the provider via the common coupling point. Medium voltage power converter after Claim 14 , which further comprises a controller which, when the provider is the power source, enables the SiC back output stage to be operated as an inverter and the active IGBT front output stage as a rectifier. A transformer for a medium voltage power converter, comprising: a plurality of core legs suitably arranged between a first pillar and a second pillar, each of the plurality of core legs having: a set of primary windings which are arranged to fit around the corresponding core leg; and a set of secondary windings that are arranged to fit around the set of primary windings. Transformer after Claim 16 wherein each of the plurality of core legs is associated with a phase of a three-phase power supply. Transformer after Claim 17 , wherein the set of primary windings for a first core leg is connected in parallel. Transformer after Claim 16 , wherein: each of a first set of secondary windings, which are arranged to fit around the set of primary windings which are arranged to fit around a first core leg, is coupled to one of a first power cube, the first power cube being a low-frequency front-end stage , a DC intermediate circuit and a high-frequency back-stage, a second power cube that includes a low-frequency front-end stage, a DC intermediate circuit and a high-frequency back-stage, and a third power cube that has a low-frequency front Output stage, a DC intermediate circuit and a high-frequency back-end stage comprises; each of a second set of second secondary windings, which are arranged around the set of primary windings to fit around a second core leg, are coupled to one of the first power cube, the second power cube and the third power cube; and each of a third set of secondary windings, which are arranged to fit around the set of primary windings to fit around a third core leg, is coupled to one of the first power cube, the second power cube and the third power cube. Transformer after Claim 19 , the plurality of secondary windings providing symmetrical impedance for the plurality of power cubes. Transformer after Claim 19 , wherein each of the set of primary windings has a first separation distance of at least two inches to ensure mutual decoupling from one of the set of primary windings. Transformer after Claim 21 , wherein the plurality of secondary windings to provide control stability provides part of the symmetrical impedance for the plurality of power cubes. Transformer after Claim 22 each of the set of primary windings from the set of secondary windings has a second separation distance of at least half an inch. Medium voltage power converter, comprising: a cabinet comprising: a power cube receptacle for receiving a plurality of power cubes, each of the plurality of power cubes being fitted within a corresponding housing and comprising a low-frequency front power amplifier, a DC intermediate circuit and a high-frequency back power amplifier, the plurality of power cubes being coupled a high speed machine is provided; and a plurality of first barriers adapted to direct an isolated first flow of cooling air through one of the plurality of power cubes; and a transformer receptacle with at least one transformer for coupling between a supply connection and the plurality of power cubes, the transformer receptacle having a plurality of cooling fans for cooling the at least one transformer. Medium voltage power converter after Claim 24 , wherein the cabinet at least a first opening for redirecting the first cooling air flow from the transformer receptacle to the power cube receptacle and at least a second opening to the Conducting an air flow emerging from the plurality of power cubes from the power cube holder to the transformer holder. Medium voltage power converter after Claim 25 , wherein the plurality of cooling fans is provided for extracting the emerging air flow. Medium voltage power converter after Claim 24 , wherein the cabinet includes a permeable element to allow a second flow of cooling air from an external environment to be directed through the plurality of cooling fans through the at least one transformer. Medium voltage power converter after Claim 24 , the cabinet comprising a sealed housing. Medium voltage power converter after Claim 24 , with the transformer receptacle being air-cooled and the power cube receptacle being liquid-cooled. Medium voltage power converter after Claim 29 , whereby the power cube holder is isolated from the transformer holder. Medium voltage power converter after Claim 30 wherein the power cube mount includes: a heat exchanger to extract heat from the first cooling air stream; a first opening to allow the first flow of cooling air to pass through the plurality of power cubes; and a second opening to direct a flow of heated air from the plurality of power cubes to the heat exchanger. System comprising: a medium voltage power converter comprising: a first cabinet that includes: a power cube receptacle for receiving a plurality of power cubes, each of the plurality of power cubes being fitted within a corresponding housing and comprising a low-frequency front power amplifier, a DC intermediate circuit and a high-frequency back power amplifier, the plurality of power cubes being coupled a high speed machine is provided; a transformer holder with at least one transformer for coupling between a supply connection and the plurality of power cubes, the transformer holder including: a plurality of cooling fans for cooling the at least one transformer; and wherein the at least one transformer comprises: a plurality of core legs that fit between a first pillar and a second pillar, wherein: a first core leg includes a first plurality of cooling plates mating therein, a first set of primary windings mating around the first plurality of cooling plates, and a first set of secondary windings mating around the first set of primary windings; a second core leg includes a second plurality of cooling plates mated therein, a second set of primary windings mating around the second plurality of cooling plates, and a second set of secondary windings mating around the second set of primary windings ; a third core leg includes a third plurality of cooling plates mating therein, a third set of primary windings mating around the third plurality of cooling plates, and a third set of secondary windings mating around the third set of primary windings . System according to Claim 32 further comprising: a first cooling plate matingly disposed on at least a portion of the first column; and a second cooling plate matingly disposed on at least a portion of the second column. System according to Claim 32 , wherein the first cabinet is sealed from an external environment, wherein at least a first opening is provided between the transformer receptacle and the power cube receptacle to ensure a first cooling air flow from the transformer receptacle to the power cube receptacle, and at least a second opening between the transformer receptacle and the Power cube holder is provided to ensure an exhaust air flow from the power cube holder to the transformer holder. System according to Claim 32 , further comprising a plurality of first barriers adapted to direct an isolated first flow of cooling air through one of the plurality of power cubes. System according to Claim 32 further comprising a first two-phase cooling system for cooling the at least one transformer via the first, second and third plurality of cooling plates. System according to Claim 36 which further includes a second two-phase cooling system for cooling comprises at least the low-frequency front-end stage and the high-frequency back-end stage of the plurality of performance cubes. Device comprising: a cabinet with a medium-voltage power converter, the cabinet having: a power cube receptacle for receiving a plurality of power cubes, each of the plurality of power cubes being fitted within a corresponding housing and comprising a front end stage, a DC intermediate circuit and a back end stage; a plurality of first barriers adapted to direct an isolated flow of cooling air through one of the plurality of performance cubes; and a transformer receptacle with at least one transformer for coupling between a supply connection and the plurality of power cubes, the transformer receptacle having: a plurality of cooling fans for guiding the cooling air flow, the cabinet at least one first opening for guiding the cooling air flow from the transformer receptacle to the power cube receptacle and has at least one second opening for guiding an air flow emerging from the plurality of power cubes from the power cube holder to the transformer holder. Device after Claim 38 , further comprising: a first plurality of cooling plates matingly disposed on a first core leg of the at least one transformer and disposed between the first core leg and a first set of primary windings matingly disposed around the first core leg; a second plurality of cooling plates matingly disposed on a second core leg of the at least one transformer and disposed between the second core leg and a second set of primary windings matingly disposed around the second core leg; and a third plurality of cooling plates, which are arranged to fit a third core leg of the at least one transformer and which are arranged between the third core leg and a third set of primary windings, which is arranged around the third core leg. Device after Claim 39 further comprising: a first cooling plate matingly disposed on at least a portion of a first column of the at least one transformer; and a second cooling plate matingly disposed on at least a portion of a second column of the at least one transformer. Device after Claim 38 , further comprising a first two-phase cooling system for cooling the at least one transformer via the first, second and third plurality of cooling plates and a second two-phase cooling system for cooling at least the plurality of power cubes. Device after Claim 38 , the cabinet comprising a sealed housing. Device after Claim 38 further comprising a plurality of choke coils fitted within the transformer receptacle, each of the plurality of choke coils being connected between the at least one transformer and a corresponding one of the plurality of power cubes.

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