DE102019008177B4 - HIGH-FREQUENCY MEDIUM-VOLTAGE DRIVE SYSTEM FOR HIGH-SPEED MACHINE APPLICATIONS - Google Patents

Abstract

Medium-voltage power converter, comprising:
a plurality of discs (225), each comprising:
a transformer (230) comprising a plurality of segmented primary windings (816) arranged side by side around a transformer leg (815), the plurality of segmented primary windings (816) for coupling to a supply source of input power and a plurality of segmented secondary windings (818); and
a plurality of power cubes (240, 1100) connected to the plurality of segmented secondary windings (818), each of the plurality of power cubes (240, 1100) comprising an active low-frequency front-end stage (242, 246), a DC link, and a high-frequency silicon carbide (SiC) inverter stage (244, 248) for coupling to a high-frequency load or a high-speed machine (145),
wherein the high frequency load comprises a high speed machine (145, 340) operating at a frequency between 500-1000 Hertz, wherein the input power supply source is intended to operate at a frequency of 50/60 Hertz.

Description

This invention was made with government support under the funding code DE- EE0007254 of the Department of Energy. The government has certain rights to 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 demanding requirements of various industries to improve overall system performance and cost. Particular challenges for the systems include operation at higher fundamental frequencies than currently possible, e.g., up to 1000 Hertz (Hz) for direct drive applications, high-power MV drives to meet mid-range power demands (e.g., up to 20 Megawatts (MW)), overall converter system efficiencies better than 97%, and reduced volumetric power density and footprint to improve system power density and cost. Current systems are not capable of such operation.

Rather, traditional multi-megawatt and multi-level medium-voltage power converter technologies based on silicon devices operate in the range of fundamental frequencies of 0-120 Hz, switching at 600 Hz, and efficiencies 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 power density reductions. US 2012 / 0 327 602 A1 shows a medium-voltage power converter comprising a transformer with primary and secondary windings and a plurality of power cubes. A power cube contains a rectifier bridge, an H-bridge inverter, and capacitors arranged between them. A system comprises a plurality of power cells. DE 11 2014 002 276 T5 shows a power converter with multiple power amplifier units, each with multiple slices. The power amplifier units are configured to process 15 MVA of power bidirectionally between a supply network and a load network via 24/4, 16 kV step-down transformers. A power cube comprises an active front end and an H-bridge inverter. Shenoy, P. et al., Commercializing medium voltage VFD that utilizes high voltage SiC technology, 2017 IEEE International Workshop On Integrated Power Packaging (IWIPP). IEEE, 2017. pp. 1-4 , describes a variable frequency drive (VFD) power architecture consisting of two identical inverter modules. Specifically, a VFD system is discussed that utilizes high-speed, high-voltage, and high-power density switching devices using silicon carbide (SiC) MOSFET technology. US 6 850 424 B2 This describes an inverter that contains both a line-side and a load-side free-running pulse converter, electrically connected via a DC link. The two free-running pulse converters each contain switchable current valves in the form of high-blocking-voltage silicon carbide semiconductor switches. CN 1 05 225 794 A shows a three-phase, five-pole high-frequency transformer with a fan-cooled structure that includes a magnetic core. The structure of the magnetic core and the winding has important effects on the performance of the transformer. DE 20 2010 004 898 U1 describes a three-phase transformer that has at least two galvanically isolated low-voltage windings. US 2017 / 0 280 593 A1 describes a cooling system for electronic devices comprising an evaporator, a frame to which the electronic devices can be mounted above the evaporator, and a condenser spaced from the evaporator. US 2014 / 0 062 635 A1 shows a magnetic core for a magnetic component with a winding, which includes an improved cooling device. The magnetic core extends longitudinally and includes a stack of laminations of magnetic material and a plate of heat-conducting material. A heat-carrying fluid circulates in a cooling tube arranged in contact with a first side of the plate. WO 2011/ 038 184 A1 shows a pumped multiphase transformer cooling system which uses a cold plate evaporator arranged between, insulated from, and in thermal contact with the core and winding of the transformer.

Task and solution of the invention

The invention provides a medium-voltage power converter having the features of claim 1 or claim 12. The invention further provides a transformer having the features of claim 15 and a system having the features of claim 23. One aspect of the invention includes a medium-voltage power converter comprising a plurality of disks, each having: a transformer having a plurality of primary windings for coupling to a supply source of 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 comprising a low-frequency front-end stage, a DC voltage voltage (DC) link and a high-frequency silicon carbide (SiC) inverter stage for coupling to a high-frequency load or a high-speed machine.

In one embodiment, the medium-voltage power converter further comprises one or more sensors coupled to an input of the medium-voltage power converter to receive sensor information. The medium-voltage power converter may further comprise a circuit breaker system coupled between the input power supply source and the medium-voltage power converter. The circuit breaker system may actively connect or disconnect the medium-voltage power converter to the input power supply source based at least in part on the sensor information. The medium-voltage power converter may further include a grid interface controller for storing and providing support functions for a high-speed electrical machine coupled to a high-speed mechanical load and a utility grid. The high-frequency load may be a high-speed machine operating at a frequency between 500-1000 Hertz, wherein the input power supply source is to operate at a frequency of 50/60 Hertz. The low-frequency front-end stage may be a SiC-based active front-end stage. Each of the plurality of power cubes includes a housing having a plurality of AC bus bars offset toward a first surface of the power cube. A DC bus of the DC interconnect may include a plated assembly offset toward a second surface of the power cube, the plated assembly having a first horizontal section with gate drive openings formed directly therethrough. The DC bus may further include a second horizontal section 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 about 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 plurality of gate drive interfaces through which connections are suitably configured to communicate gate drive signals.

Another aspect of the invention includes a medium voltage power converter comprising: 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 power cubes of the disk, each of the plurality of power cubes comprising an active insulated gate bipolar transistor (IGBT) front end stage, a DC link, and a SiC back end stage for coupling to a load at a second frequency, the second frequency being greater than the first frequency.

In one embodiment, when a power source is present instead of a load, the SiC back output stage is intended to operate as a rectifier and the active IGBT front output stage as an inverter to enable the generated power to be supplied to the utility via the common coupling point. The medium-voltage power converter can further include a controller that ensures that, when the utility is the power source, the SiC back output stage operates as an inverter and the active IGBT front output stage operates as a rectifier.

Another aspect of the invention includes a transformer for a medium-voltage power converter comprising: a plurality of core legs matingly disposed between a first column and a second column, each of the plurality of core legs having: a set of primary windings matingly disposed around the respective core leg; and a set of secondary windings matingly disposed 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 may be connected in parallel. In one embodiment, each of a first set of secondary windings, which are mateably arranged around the set of primary windings mateably arranged around a first core leg, is coupled to one of a first power cube, the first power cube comprising a low-frequency front-end stage, a DC intermediate circuit, and a high-frequency back-end stage, a second power cube having a low-frequency front-end stage, a DC intermediate circuit, and a high-frequency back-end stage, and a third power cube having a low-frequency front-end stage, a DC current interposer and a high frequency back-end stage; each of a second set of secondary windings, matingly disposed around the set of primary windings matingly disposed around a second core leg, is 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, matingly disposed around the set of primary windings matingly disposed around a third core leg, is 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 provides a symmetrical impedance to 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 provide decoupling from one another. The plurality of secondary windings provides a portion of the symmetrical impedance to the plurality of power cubes to ensure control stability. Each of the set of primary windings may be spaced from the set of secondary windings by a second separation distance of at least one-half inch.

Another aspect of the invention includes a medium-voltage power converter comprising a cabinet having: a power cube receptacle for receiving a plurality of power cubes, each of the plurality of power cubes being fitted within a respective housing and comprising a low-frequency front-end stage, a DC link, and a high-frequency back-end stage, the plurality of power cubes being adapted for coupling to a high-speed machine; and a plurality of first barriers adapted for directing an isolated first cooling airflow through one of the plurality of power cubes; and a transformer receptacle having at least one transformer for coupling between a supply terminal 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 redirect the first cooling airflow from the transformer receptacle into the power cube receptacle, and at least a second opening to direct an airflow exiting the plurality of power cubes from the power cube receptacle into the transformer receptacle. The plurality of cooling fans can exhaust the exiting airflow. The cabinet can include a permeable element to allow a second cooling airflow from an external environment to be directed through the at least one transformer via the plurality of cooling fans. The cabinet can be configured as a sealed enclosure. In one example, the transformer receptacle is to be air-cooled and the power cube receptacle is to be liquid-cooled. The power cube receptacle can be insulated from the transformer receptacle.

In one embodiment, the power cube receptacle includes: a heat exchanger for extracting heat from the first cooling air stream; a first opening for allowing the first cooling air stream to be directed 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 a system comprising one or more medium-voltage power converters, each of which may include a first cabinet having: a power cube receptacle for receiving a plurality of power cubes, each of the plurality of power cubes being fitted within a respective housing and comprising a low-frequency front-end stage, a DC link, and a high-frequency back-end stage, the plurality of power cubes being adapted for coupling to a high-speed machine; a transformer receptacle having at least one transformer for coupling between a supply terminal and the plurality of power cubes. The transformer receptacle may 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 matingly disposed between a first column and a second column, wherein: a first core leg has a first plurality of cooling plates matingly disposed therein, a first set of primary windings matingly disposed around the first plurality of cooling plates, and a first set of secondary windings matingly disposed around the first set of primary windings; a second core leg has a second plurality of cooling plates matingly disposed therein, a second set of primary windings matingly disposed around the second plurality of cooling plates, and a second set of secondary windings matingly disposed around the second set of primary windings; a third core leg has a third plurality of cooling plates, a third set of primary windings arranged around the third plurality of cooling plates, and a third set of secondary windings arranged around the third set of primary windings.

In one embodiment, the system further includes: a first cold plate matingly disposed against at least a portion of the first column; and a second cold plate matingly disposed against at least a portion of the second column. The first cabinet may be sealed with respect to an external environment, with at least a first opening provided between the transformer receptacle and the power cube receptacle to provide a first cooling airflow from the transformer receptacle to the power cube receptacle, and at least a second opening provided between the transformer receptacle and the power cube receptacle to provide an exhaust airflow from the power cube receptacle to the transformer receptacle.

In one example, the system further comprises a plurality of first barriers configured to direct an isolated first cooling airflow 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 cold 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.

In another embodiment, an apparatus 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 fitted within a respective enclosure and comprising a front-end power stage, a DC link, and a back-end power stage; a plurality of first barriers adapted to direct an isolated cooling airflow through one of the plurality of power cubes; and a transformer receptacle having at least one transformer for coupling between a supply terminal and the plurality of power cubes. The transformer receptacle may include: a plurality of cooling fans for directing the cooling airflow, the cabinet comprising at least one first opening for directing the cooling airflow from the transformer receptacle to the power cube receptacle, and at least one second opening for directing an airflow exiting the plurality of power cubes from the power cube receptacle to the transformer receptacle.

In one embodiment, the apparatus further includes: a first plurality of cooling plates mateably disposed 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 mateably disposed around the first core leg; a second plurality of cooling plates mateably disposed around a second core leg of the at least one transformer and disposed between the second core leg and a second set of primary windings mateably disposed around the second core leg; and a third plurality of cooling plates mateably disposed around a third core leg of the at least one transformer and disposed between the third core leg and a third set of primary windings mateably disposed around the third core leg.

In one embodiment, the apparatus may further include: a first cold plate matingly disposed against at least a portion of a first column of the at least one transformer; and a second cold plate matingly disposed against 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 cold plates and a second two-phase cooling system for cooling at least the plurality of power cubes. The cabinet may be a sealed enclosure. The apparatus may further include a plurality of reactors matingly disposed within the transformer receptacle, each of the plurality of reactors being connected between the at least one transformer and a corresponding one of the plurality of power cubes.

Short description of the characters

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

Detailed description

In various embodiments, a modular high-speed and high-frequency medium-voltage system converter can be realized using a wide-band 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 converter and a high-speed induction machine can be coupled to enable bidirectional power transfer. The power transfer occurs between a utility grid and a mechanical load. In further embodiments, the power conversion system can be connected to an electrical or other high-speed load that can serve as a source, allowing the system to transfer the collected energy to a utility grid at the appropriate voltage and current.

The system design can be based on complete WBG devices such as silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) for high-efficiency systems, or on active insulated-gate bipolar transistor (IGBT) front-end devices for low-cost applications, where system derating is permitted and minimum system power density and footprint are not constraining. In another embodiment, a hybrid power topology (e.g., IGBT and SiC power MOSFET combinations) can be used to facilitate electrical switching requirements or for cost reduction considerations while maintaining acceptable overall system performance.

In 1 Now, a schematic diagram of a power converter environment according to an embodiment of the present invention is shown. More specifically, as shown in 1 shown, the power converter environment 100 is implemented with a modular high-speed and high-frequency medium-voltage system converter with a hybrid converter arrangement in the manner described above. 1 In the illustrated embodiment, a system converter 115 is connected via a point of common coupling (PCC) to a utility grid (which may operate at a frequency of 50 or 60 Hz depending on the country) through a circuit breaker system 105. For example, the system converter 115 in turn couples 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 can be implemented as a 1.8-2.3 MVA high-frequency converter with a nominal voltage of 4160 volts (V) and operable between 500-1000 hertz (Hz). As shown, the system converter 115 can include a multi-slice arrangement with a single line controller where a converter system controller is located, and three slices implemented as subsystem 120. In the overview view in 1 It should be noted that subsystem 120 consists of slices with hybrid technology, namely front ends consisting of IGBTs and back ends consisting of SiCs, resulting in a hybrid topology. As used herein, the term "slice" refers to a portion of a power conversion system that includes at least one transformer and several so-called power cubes comprising semiconductor switching devices. A slice-based system thus couples between a line terminal capable of operating at a first, low frequency and a load terminal capable of operating at a second, high frequency. And, as described herein, the direction of power flow through a slice can be bidirectional, depending on the given system implementation and control configuration. It should be noted that the term "low frequency" as used herein refers to a utility frequency—generally less than 100 Hz, and more specifically, 50 or 60 Hz. And the term "high frequency," as used herein, refers to operation at a frequency significantly higher than the utility frequency. Representative applications of a power converter, for example, can be coupled to high-frequency loads between approximately 500 Hz and 1000 Hz.

Although in 1 While illustrated as a hybrid topology, it should be understood that in other implementations, a full WBG-based topology may exist. With associated electronics, this arrangement of the system inverter 115 is also referred to herein as a modular power building block (MPBB). Details of a specific MPBB and slice are described in more detail below. As illustrated, the subsystem 120 couples between an input from the utility grid via a vacuum contactor VC1 and a transient voltage suppression (TVS) protector D1. In turn, an output of the subsystem 120 couples via a 3-phase, single-shielded power cable 129 to another enclosure 140 containing an electric machine 145.

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

Furthermore, with reference to 1 Details of the high-speed machine 140 are also shown. As illustrated, in one embodiment, the high-speed machine 140 may be rated at 4160 V and 15,000 rpm, or other higher voltage and speed ratings. The high-speed machine 140 includes an electric machine 145 that receives three-phase power via a shielded power cable 129. Measurements related to the parameters of the electric machine 145 may be performed by various components, including RTDs 143, the outputs of which may be sent over a fiber optic connection via an RTD-to-fiber converter 142, accelerometers 152, proximity switches 154, and a key-phasor 156. As shown, these components may be connected to a controller, namely a network interface controller 160, which may be connected over fiber optic interfaces is further coupled to the system PLC 126 of the system inverter 115. In a preferred embodiment, the grid interface controller 160 is located within the MPBB 115 and provides advanced support functions for the high-speed machine 140, a high-speed mechanical load controller 165, and a grid system manager 170. In addition, the grid interface controller 160 provides local smart capability by storing and processing connection information, e.g., advanced support function algorithms.

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

In 2A A schematic diagram of a representative SiC-based modular power building block (MPBB) 200 is shown. In typical implementations, modularity can be achieved by a system converter with multiple MPBBs. However, for better illustration, 2A only a single MPBB is shown. In the embodiments, the MPBB 200 can be implemented in one or more modular housings, e.g., in a series of cabinet housings. With respect to MPBB 200, a plurality of disks 225 ₁ -225 ₃ are present. In an example of a modular implementation, each disk 225 can be implemented in its own disk cabinet. Although for simplicity of illustration in 2 If not shown, it is to be understood that an MPBB may also include a further cabinet to accommodate a network control and the associated electronic circuits, as shown in the overview view of the 1 shown.

As can be seen, each slice 225 includes 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 in a DELTA configuration. More specifically, each transformer 230 includes a plurality 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 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 are connected in parallel at the input (GRID). As shown, the secondary windings of the transformers 230 in turn couple to corresponding power 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 inversion operations to condition a power flow, including converting incoming power at a first frequency into outgoing, conditioned power at a second frequency. Depending on the direction of power flow, the first frequency may be higher than the second frequency, or vice versa.

In the overview view in 2A and as shown in particular in the circuit diagram in 2B As 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 formed from a plurality of SiC switching devices, a DC bus implemented with a capacitor C1, and an H-bridge converter stage 244 implemented with another plurality of SiC switching devices. It should be noted that component 242 is a rectifier and component 244 is an inverter when the power in the block diagram is 2B flows from left to right. When power flows from right to left, component 242 operates as an inverter and component 244 as a rectifier. AFE means that the stage is actively controlled. In this embodiment, the switching frequency of the SiC devices is set between 4 and 12 kHz, but other switching frequencies can be used depending on the various operating requirements (e.g., 2-phase cold plate temperature withstand limit) and the desired performance goals (e.g., control stability of the DC bus regulation). For example, in generation mode (from right to left on power cube 240), the specified active power is drawn on the single-phase AC side at 740 VAC and processed by power converter stage 244 according to a PWM control scheme. This power is transferred via the capacitor bank C1 of the DC link, which is regulated to 1000VDC by the power stage 242 using an SVPWM control scheme, and delivered on the 3-phase AC side at 600V. The collected system power energy is transferred to the power grid via the circuit breaker system 105, which is controlled by control actions implemented on the grid interface controller 160. During motor operation, the active power flows according to the opposite Control process from left to right. During this mode of operation, the high-speed machine system 140 can be controlled using a speed control algorithm implemented on the MSCB 124.

In the execution in 2C An alternative embodiment of a power cube is schematically illustrated. Here, the power cube 240' is implemented with a hybrid topology comprising a front end 246 of IGBTs, a DC bus represented by a capacitor C1, and a back end stage 248 comprising SiCs. As with the discussion above, depending on the direction of power flow, either the front end stage 246 or the back end stage 248 can 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 is set between 6 kHz and 12 kHz, although other switching frequencies may be used depending on operating requirements and desired power goals. The primary advantage of the power topology of the power cube 240' can be a low-cost system implementation. The back-end stage 248 can be implemented with SiC-based devices (e.g., 1700V SiC power MOSFETs) and the front-end stage 246 can be implemented with low-cost Si-based devices (e.g., 1700V IGBTs).

In 3 A schematic representation of a system according to another embodiment of the present invention is now shown. As in 3 As shown, the system 300 is implemented as a multi-megawatt scale power converter system 310. More specifically, the representative power converter 310 is implemented as a scalable, all-SiC-based multi-megawatt power converter with a plurality of modular drive enclosures _3151-315n or SiC MPBBs, each containing a multi-slice system converter _3201-320n . Each MPBB 315 contains a multi-slice system converter 320 and a power cabinet (system controller, output/input sensors, input/output AC connections). The number of MPBBs comprising a particular power converter is design-dependent and depends on the power requirements.

As shown, the power converter 310 is connected to a grid 302 capable of supplying three-phase power at 13.8 kilovolts (kV). As seen, the power converter 310 couples to the grid 302 via a PCC. The power converter 310, in turn, can couple to various loads, including a high-speed electrical machine 340, which can be coupled to a high-speed mechanical load or other electrical machine system (not shown). As illustrated in the illustrated embodiment, each power converter 310 can output three-phase power at 4.16 kV at a specific frequency (e.g., between 500-1000 Hz) or a higher voltage rating for other high-speed machine systems.

With respect to the representative power conversion system 310, the incoming power is provided via a circuit breaker system 305 to an input of a particular drive enclosure 315. In an exemplary embodiment, this input power may be provided at 74 amperes (A). And in one embodiment, each MPBB 315 including a set of disks may provide an output power at 350 A. In the 3 In the overview view shown, each MPBB 315 can be connected to an input of the discs as described above in 1 described components, including vacuum contactor, TSV diode.

As further illustrated, sensors 312 _1A and 312 _1B may be provided at the input and output of the disks, respectively. In one embodiment, such sensors may include 100A and 500A LEM sensors for 13.8kV/4.16kV MPBB systems to provide information about disk operation and implement system protection and grid connection. In particular, grid-side coupled circuit breaker system 305 may, based on sensor data, respond to converter commands in a system-controlled manner to connect or disconnect power converter 310 to grid 302 during normal system operation or during system fault events. Note that in embodiments, sensors such as sensors 312 as depicted may be located locally or remotely 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 grid connection and a high-frequency load. For example, the MPBB's input can be connected to a grid connection operating at 3-phase 60 Hz, 13.8 kV, and the MPBB's output can provide output power for a high-frequency load operating at 500 Hz, 4.16 kV, 3-phase, for example. Conversely, the MPBB can connect a high-frequency generator operating at 500 Hz, 4.16 kV, 3-phase, for example, to a 3-phase grid connection operating at 60 Hz, 13.8 kV.

In one embodiment, a fiber-based SiC gate driver interface may be implemented to improve system noise immunity and provide local To enable control signal management. It can be adapted to any off-the-shelf or custom-built dual SiC-based device solution. In one embodiment, the interface can be conveniently located on a circuit board, which can be placed directly above a device gate driver to minimize inductive coupling during signal interfacing. An FPGA chip can be used onboard to locally implement smart features to improve the performance of SiC devices and simplify packaging within that package. Interference of control and status signals can be reduced between the controller and half-bridge gate drivers due to high electrical noise environments in SiC systems. A simplex fiber optic cable can be used to transmit the half-bridge switching states and gate driver control from the controller to the gate driver. A simplex fiber optic cable 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 4 Now, a block diagram of an interface circuit according to an embodiment of the present invention is shown. More specifically, as shown in 4 As shown, the interface circuit 400 may be implemented with a fiber optic-based SiC gate driver interface to control the various switching components of a wafer as described herein.

As shown, the interface circuit 400 includes a cube controller 410 that can generate various control and switching signals, e.g., based on feedback status information as well as control information received from a higher-level controller (e.g., a disk controller included in 4 not shown for clarity). The cube controller 410 is illustrated as being connected to a plurality of interfaces 420 ₁ -420 _n . As can be seen in the representative interface 420 ₁ , a DC/DC power supply 425 is included that powers a Gate Drive Fiber Interface (GDFI) fiber optic interface controller 430, which in turn is coupled to a general purpose SiC gate driver 435. Such a gate driver may in turn be connected to a half-bridge SiC or IGBT module 440. Note that SiCs/IGBTs themselves are not present at an interface 420 and, as described in more detail below, they are connected beneath the interface card and directly onto a cold plate. As illustrated, the cube controller 410 may communicate various information, including gate state and control signals, to the controller 430 optically over fiber optics. IGBT and drive status can also be reported back to the cube controller 410 via fiber optic communication (these bidirectional signals are shown collectively as signals 450).
To ensure communication between the controller 430 and the gate driver 435, copper connections can be used.

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

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

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

In 5 500 is a side view of a power converter cabinet according to one embodiment. Note that the cabinet 500 is a disk cabinet (with a single transformer and 3 power cubes). It should be understood that, as in 2 defined, in one embodiment, an MPBB comprising 3 cabinet panes is manufactured. As shown in the cross-sectional view in 5 As shown, the cabinet 500 includes a transformer section 510 and an inverter section 550. As shown, the transformer section 510 includes a transformer 515 with multiple transformer legs 515 ₁ -515 ₃ . In this design, the incoming air can be directed, for example, via a grille or other permeable element at a front portion of the cabinet 500. As can be seen, the incoming airflow is directed through the transformer legs 515 by means of a plurality of cooling fans 520 ₁ -520 ₃ , which direct the exhaust air through the rear of the cabinet 500. A mechanical barrier for separating the cube and transformer sections can be implemented as a horizontal barrier made of GPO-3 polyester material. This barrier has openings at 568 and 570, as shown.

In turn, additional air is directed from the transformer section 510 to the inverter section 550 via one or more openings 568, where it flows through a plurality of power cubes 560 ₁ -560 ₃ . Note that in embodiments, mechanical barriers 565 ₀ -565 ₃ , e.g., made of GPO-3 polyester material, force the airflow from the opening 568 through the power cubes 560 ₁ -560 ₃ for proper cooling of the system. In this way, each power cube receives a supply of fresh air for cooling, which is then exhausted from the back of the cubes 560 and downward through one or more openings 570 back into the transformer section 510. These mechanisms ensure air circulation, with the air being directed outside via fans 520. This way, the transformer legs 515 and the power cubes 560 receive fresh air from outside and the air is expelled at the rear of the cabinet.

In 6 A side view diagram of a power converter cabinet according to another embodiment is shown. As shown in the cross-sectional view in 6 As shown, the cabinet 600 includes a transformer section 610 and an inverter section 650. As shown, the transformer 615 has a plurality of transformer legs 615 ₁ -615 _3. In this embodiment, the supply air can be taken in, for example, via a grille on a front part of the cabinet 600. As can be seen, the incoming air flow is directed through the transformer legs 615 by means of a plurality of cooling fans 620 ₁ -620 ₃ , which direct the exhaust air over the rear of the cabinet 600. As shown in 6 As shown, the transformer section 610 can be air-cooled in the same manner as described above with respect to 5 discussed. In contrast to the embodiment in 5 offers 6 However, an arrangement in which the inverter section 650 is liquid-cooled is possible. Thus, the inverter section 650 can remain sealed from the transformer section 610, so that no air exchange with the transformer section 610 occurs.

As further shown, cooling for the inverter section 650 may be provided via a cooling section 680, which provides a flow of liquid coolant to the inverter section 650 using 2-phase cooling in a sealed manner. To enhance heat dissipation of the power cube, the 2-phase liquid may be circulated through a heat exchanger externally connected to the cabinet 600. With the cooling fans 670 provided in the inverter section 650, the air may be recirculated throughout the entire inverter section 650. In some embodiments, to implement the liquid cooling capability within the inverter section 650, an extended cabinet with a bumpout section may be provided. The barriers 665 ₀ - 665 ₃ direct the cooling air flow of the cooling fans 670 through the power cubes 660 ₁ - 660 ₃ .

In yet another embodiment, both transformer and power cubes, as in 7 shown, 2-phase liquid cooled to maximize heat dissipation of the discs. In 7 A side view of a power converter cabinet according to another embodiment is now shown. As in the cross-sectional view in 7 As shown, the cabinet 700 includes a transformer section 710 and an inverter section 750. As shown, a transformer 715 includes multiple transformer legs 715 ₁ -715 ₃ . Note that the cabinet 700 is sealed from the outside air, but air exchange occurs between the transformer section 710 and the inverter section 750 via openings 768 and 770. In one embodiment, a heat exchanger 790 is installed between the transformer section 710 and the internal fans 720 to maintain air circulation through the transformer coils and power cubes. In addition to the heat exchanger 790, one or more cold plates can also be arranged directly on the transformer cores. Thus, as in 7 shown, the cooling plates 796, 798 are arranged on the front and rear parts of the transformer 715. As shown in the overview view in 7 As shown, the heat exchanger 790 may include coolant ports 792, 794 for directing a coolant flow through the heat exchanger 790. Similar cooling of the inverter section 750 by directing the cooled air provided via opening 770 enables cooling of corresponding power cubes 760, with the heated air flowing back to the transformer section 710 via opening 768. The barriers 765 ₀ - 765 ₃ direct the cooling air flow from the cooling fans 720 further through the power cubes 760.

In still further embodiments, the additional cooling of a transformer can be realized by providing cold plates on the surfaces of the cores of the transformer. In one embodiment, each core leg can be provided with between 2 and 4 cold plates with a width of e.g. 6 inches. To improve the heat transfer of the transformer cores, additional cold plates can be located on the front and back of the transformer, which are arranged on the columns of the transformer. In the figure, 8A Details of a cooling arrangement for transformers shown. In a side view 810 in 8A The transformer legs 815 ₁ -815 ₃ are shown. The cold plates 820 are suitably arranged at the front and rear of the transformer columns 811, 812, which include the connections 822, 824 for conducting a flow of liquid coolant. In addition, a plurality of cold plates 840 ₁ -840 ₆ are provided. As can be seen, each cold plate 840 can be installed above and below the core legs and each can include a corresponding coolant connection 842 to ensure a flow of liquid coolant. As in 8A As further illustrated, insulation and air channels may be present between different transformer windings and cold plates.

Still with reference to 8A is shown an arrangement of the windings of the transformer 815. More specifically, the transformer 815 includes a separate winding structure in which several separate windings, both primary and secondary, are provided for each transformer leg 815. In the 8A The view shown shows three separate primary windings 816 ₁ -816 ₃ for the transformer leg 815 _1. And wound directly around each of the primary windings 816 is one of several secondary windings 818 ₁ -818 _3. Further details of this side-by-side or separate winding arrangement are described below.

8B and 8C also show layouts for liquid cooling. In particular, 8B A rear view of a transformer 815, in which a cold plate 820 is arranged on this rear side of the transformer. Note that a corresponding cold plate can also be installed on the front of the transformer. Also shown are the coolant connections 822, 824. And 8C shows a cross-sectional view of a transformer column, further illustrating cold plates that can be suitably arranged on corresponding sides of the core legs 815. It should be noted that with a generally rectangular or square cross-section of the core legs 815, a cold plate can be arranged substantially flat or flush with a particular surface of a core leg. Thus, as in 8C shown, each core leg 815 may have additional corresponding cold plates 845 adapted to the sides thereof.

In 8D Now, an illustration of a transformer according to an embodiment is shown. More specifically, in 8D An electrical arrangement of the transformer 815 is shown without cooling structures in order not to obscure any details of the segmented winding arrangement. As shown, the transformer 815 is formed with a plurality of core legs 815a-815c, each coupled between a first column 811 and a second column 813. In one embodiment, the core legs 815 and the columns 811, 812 can be made of iron. In the detailed arrangement of the first core leg 815a, which can correspond to a first phase (phase A), a plurality of primary windings 816a _, 1-816a _,3 with a segmented winding structure are present, which are wound around the core leg 815a. It should be noted that in 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 818 _a,1 - 818 _a,3 are wound directly around the corresponding primary windings. The separation between primary and secondary windings determines the equivalent inductance per phase on the secondary side of transformer 815. The recommended value of leakage inductance to support control stability of each AFE power stage is achieved by a minimum spacing between the windings. In other words, there can be a corresponding minimum spacing between the wound primary and secondary windings. For example, there can be a spacing of at least half an inch between a primary winding 816 and a corresponding secondary winding 818.

In one embodiment, a corresponding separation distance 813, 817 may 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. This magnetic effect is realized by setting a minimum horizontal distance of two inches between adjacent winding sets 816 and 818. It should be noted that for the transformer legs 815b,c of the second and third phases (which are shown in 8D shown in a limited 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 A schematic diagram is now shown showing the segmented windings in 8D correlated with the corresponding terminals of 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. And similarly, the corresponding secondary windings of a particular phase leg in a DELTA configuration couple to one of the corresponding power cubes (not shown for clarity). 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 appropriately arranged around a transformer leg and in the circuit diagram in 8E , which show the correspondences between primary and secondary windings for a first phase (AP1-AP3 and AS1-AS3). Thus, in 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 provide a highly efficient power transformer design with symmetrical secondary impedances. For each secondary winding, there are three parallel primary windings. Arranging the windings side by side 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 inductor per phase, which is used on the primary or secondary side of the transformer to ensure converter control stability. It also eliminates the need for additional filters at the converter input. In Si-based device systems, the need for an additional inductor may be permissible because the converter's AFE is switched at low frequency to keep overall loss low. The transformer is designed to operate at points A and B, as shown by the efficiency curve in 9 In one embodiment, the transformer power is in the range of 750 kVA to 1000 kVA for a disk system configuration. With symmetrical impedances, the windings are wound side by side.

In 10 A block diagram of a disk arrangement according to another embodiment of the present invention is now shown. In particular, in the embodiment in 10 a disc is further provided with additional inductance for active front-end devices by means of choke coils. As in 10 As shown, a disk cabinet 1000 includes a transformer section 1010 and an inverter section 1050. In the illustrated figure, an arrangement with air-cooled transformer and inverter sections is provided. In addition (and for comparison to the 5 (as shown in the arrangement), a plurality of AFE choke coils 1040 ₁ -1040 ₃ are provided within the transformer section 1010. These AFE choke coils implement a configuration that allows for additional inductance for Si-based designs. The required inductance can be in the range of 5%, and the switching frequency is maintained 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 may further enable efficiency improvements in the configuration of a power cube to implement SiC-based switching devices. In particular, in one embodiment, a coated DC busbar design may be used to improve the performance of WBG devices. This design may minimize parasitic inductance to improve the switching performance of SiC devices to less than 13 nH. 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 full SiC device topology with a specific SiC power module terminal layout may be used.

In another implementation, a cube topology for hybrid devices (e.g., Si IGBT-based rectifier and SiC MOSFET-based inverter) may be available, using the same concept to minimize DC link inductance. 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 power cube is shown according to one embodiment. As can be seen, the power cube 1100 is implemented in a housing 1110. The incoming 3-phase power received from a transformer secondary side is provided via a plurality of input AC busbars 1180. In one embodiment, three such input busbars are provided to couple incoming 3-phase power to corresponding front-end SiCs. As shown in 11 As shown, the AC bus bars 1180 are moved toward a rear portion of the power cube 1100 to improve heat dissipation. This is because this placement of the AC busbars 1180 simplifies the busbar design by allowing them to be manufactured with a shorter length, and the majority of their heat dissipation is not concentrated above the SiC devices or below a DC busbar. Thus, in the illustrated embodiment, the busbars 1180 can be coupled with SiCs of a front-end power stage (details are provided in 11 not shown). It should be noted that the switching of the SiC devices can be controlled via the fiber-optic SiC gate driver interfaces 1120 ₀ -1120 _n . While 5 such driver interfaces are provided in the embodiment in 11 are shown, other numbers may be present in further embodiments. For non-regenerative applications, a passive front-end rectifier may include dual diode power modules, so that only two switches are controlled (inverter side), and therefore only two driver interfaces are used. Hybrid and all-SiC topologies each use 5 controlled switches (SiC MOSFETs and/or IGBTs), therefore 5 driver interfaces are required. For parallel SiC devices, a maximum of 10 driver interfaces may be required. Control signals are provided to the driver interfaces 1120 via a SiC-based control board 1130, which is connected to the interfaces 1120 via corresponding fiber optic connections 1135. As in 11 As further illustrated, the driver interfaces 1120 are arranged above the SiC modules themselves, which in turn are arranged on a cold plate assembly 1150. Note that the power supply for various control and monitoring circuits can be provided by a power supply 1195.

As further illustrated, a DC interconnection circuit having a DC bus 1160 is formed at a front portion of the housing 1110, details of which will be described below. The DC interconnection circuit further includes, in addition to the DC bus 1160 itself, a plurality of capacitors 1165 connected thereto, one of which is 11 In one embodiment, the power cube 1100 may be implemented with a DC bus 1160 coupled to the capacitors 1165 that are sized for optimum performance. In a specific embodiment, a particular power cube may be implemented with a capacitance of approximately 7.6-11.4 millifarads (mF) for better transient and power transfer performance.

Still with reference to 11 The output power from the power cube 1100 may be output via a plurality of output bus rails 1170 which, as shown, couple to corresponding AC bus rails 1180.

To ensure cooling of SiCs and other components within the power cube 1100, the lines 1190, 1192 may be provided to conduct a flow of cooling liquid or other coolants. 11 shows the embodiment in 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 busbars; this can further simplify the AC busbar construction as described above. In this way, device terminal spacing can be increased (e.g., from 2 mils to 5 mils). And with improved electrical isolation, in one exemplary embodiment, the DC interconnect can operate between 1000-1200 VDC.

In 12 A graphical representation of a DC bus arrangement according to one embodiment is shown. As shown in 12 As shown, the DC bus 1200 may be implemented using a coated structure comprising a plurality of layers 1210 ₀ -1210 _n . In the particular embodiment shown, a five-layer arrangement is realized, however, more or fewer layers may be present in certain embodiments. As shown, the DC bus 1200 is implemented with alternating layers of conductive and insulating material. More specifically, the negative and positive DC bus layers 1210 ₁ and 1210 _{3 ,} respectively, couple between the corresponding insulating layers 1210 ₀ , 1210 ₂ and 1210 _n . In one embodiment, the DC bus layers 1210 ₁ , 1210 ₃ may be implemented using a predetermined conductive material, e.g., copper, and may have an approximate thickness of 50-100 mils. The insulating layers 1210 ₀ , 1210 ₂ , 1210 _n , in turn, can be formed with an insulating material, e.g., insulating PET materials. In a particular embodiment, the insulating layers 1210 ₀ , 1210 _n can be formed with a thickness between approximately 5-10 mils, and the insulating layer 1210 ₂ can be formed with an insulating material consisting of a layer with a thickness between 5-20 mils.

As further shown in the 1250 insert in 12 is shown with the sublime arrangement of the DC bus 1200, which consists of a first horizontal section 1275 and a second raised horizontal section 1280, realizes mechanical decoupling of AC bus bars from the intermediate circuit. As also illustrated, the configured DC bus has a plurality of recesses, including representative recesses 1260 and 1270 on the first horizontal section 1275. More specifically, the recesses 1260 provide a recess for AC buses. An AC bus bar can be bolted to a SiC device via the recess 1260. The second horizontal section 1280, in turn, can provide a connection to the capacitors of the DC intermediate circuit.

Gate driver connections can be made via the recesses 1270. This position of the recesses 1270 allows the copper area of the DC bus to be maximized and the design of the AC busbar to be simplified. This means that the AC busbars can be arranged straight from the back of the power converter. This allows for a reduction in copper (smaller AC buses) and simplification of packaging (smaller dimensions). In one embodiment, the positive and negative SiC device connection to the coated DC bus is achieved by three stamped circles arranged on each side of the recesses 1260. To improve the creepage distances of DC bus connectors, other openings for SiC device connector shapes can be used instead of groups of stamped circles. This coated arrangement, which includes the first horizontal section 1275 with gate driver openings directly through the DC bus, enables decoupling of AC bus rails and DC bus rails.

In another system design (not shown), isolation around the SiC device terminals is maximized by combining recesses 1270 and 1260 into a single opening on an insulating layer to increase the spacing to over 5 mils without significantly increasing the system's loop inductance. The same procedure can also be performed on the negative copper plate 1210 ₃ .

In 13 An arrangement with decoupled AC and DC buses is shown. More precisely, as in 13 illustrated, an arrangement of cold plates 1300 is provided on which a plurality of gate driver interfaces 1310 ₀ -1310 _n are present. As explained above, such driver interfaces provide control signals for gates of SiCs or other switching devices 1330 that are conveniently arranged below the gate driver boards (and that are coupled to the cold plate arrangement 1300). As further illustrated, a plurality of AC bus bars 1320 ₀ -1320 _n are present next to the switching devices 1330. While five such AC bus bars are shown, more or fewer may be present in certain embodiments. With this arrangement, the AC bus bars 1320 can be decoupled from a DC bus (not shown). 13 shown), but it is to be understood that such a DC bus is disposed at a rear side of the cold plate assembly 1300 (while the AC bus bars 1320 extend from a front portion of the cold plate assembly 1300). In this manner, the AC bus bars 1320 provide improved packaging for the power cubes. It should be noted that output bus bar cube connections (not in 13 shown) can be connected to AC bus bars 1320 ₃ , 1320 _n .

Claims (28)

A medium-voltage power converter comprising: a plurality of disks (225), each having: a transformer (230) comprising a plurality of segmented primary windings (816) arranged side by side around a transformer leg (815), the plurality of segmented primary windings (816) for coupling to a supply source of input power and a plurality of segmented secondary windings (818); and a plurality of power cubes (240, 1100) connected to the plurality of segmented secondary windings (818), each of the plurality of power cubes (240, 1100) comprising an active low-frequency front-end stage (242, 246), a DC link, and a high-frequency silicon carbide (SiC) inverter stage (244, 248) for coupling to a high-frequency load or a high-speed machine (145), wherein the high-frequency load comprises a high-speed machine (145, 340) operating at a frequency between 500-1000 Hertz, wherein the input power supply source is intended to operate at a frequency of 50/60 Hertz. Medium voltage power converter according to Claim 1 , further comprising one or more sensors (312) connected to an input of the means voltage-power converter to obtain sensor information. Medium voltage power converter according to Claim 2 , further comprising a circuit breaker system (105) connected between the input power supply source and the medium voltage power converter. Medium voltage power converter according to Claim 3 wherein the circuit breaker system (105) is to actively connect or disconnect the medium voltage power converter from the input power supply source based at least in part on the sensor information. Medium voltage power converter according to Claim 1 , further comprising a network interface controller (160) for storing and providing support functions for the high-speed machine, a high-speed mechanical load, and a utility network system. Medium voltage power converter according to Claim 1 , wherein the low-frequency front-end stage comprises a SiC-based active front-end stage. Medium voltage power converter according to Claim 1 wherein each of the plurality of power cubes (240, 1100) comprises a housing having a plurality of AC bus bars (1180) shifted toward a first surface of the power cube (240). Medium voltage power converter according to Claim 7 wherein a DC bus (1160) of the DC interconnect comprises a coated assembly shifted toward a second surface of the power cube (240, 1100), the coated assembly having a first horizontal section with gate drive openings formed directly therethrough. Medium voltage power converter according to Claim 8 wherein the DC bus (1160) further comprises a second horizontal portion vertically offset from the first horizontal portion for coupling to a plurality of capacitors (1165), the plurality of capacitors (1165) having a capacitance between about 7.6 and 11.4 millifarads. Medium voltage power converter according to Claim 9 , wherein the second horizontal section is provided for coupling to a plurality of capacitors (1165). Medium voltage power converter according to Claim 10 , wherein the first horizontal section comprises: a plurality of AC bus recesses through which a plurality of AC bus rails (1180) are to be coupled to at least one SiC device; and a plurality of gate driver interfaces through which connections for communicating gate driver signals are suitably established. A medium-voltage power converter comprising: a plurality of disks (225), each having a transformer (230) comprising a plurality of segmented primary windings (816) arranged around a transformer leg (815), the transformer (230) being configured for connection to a common coupling point of a utility at a first frequency, the input power supply source being configured to operate at a frequency of 50/60 Hertz, and a plurality of segmented secondary windings (818), each for coupling to one of the plurality of power cubes (240, 1100) of the disk (225), each of the plurality of power cubes (240, 1100) comprising an active insulated-gate bipolar transistor (IGBT) front-end stage (246), a DC link, and a silicon carbide (SiC) back-end stage (244, 248) for coupling to a load at a second frequency, wherein the second frequency is greater than the first frequency, and wherein the load comprises a high-speed machine (145, 340) operating at a frequency between 500-1000 Hertz. Medium voltage power converter according to Claim 12 , where, if the load is an energy source, the SiC back power stage should be operated as a rectifier and the active IGBT front power stage as an inverter to enable the generated power to be supplied to the utility via the common coupling point. Medium voltage power converter according to Claim 13 , which further comprises a control which, when the utility is the power source, enables the SiC back power stage to operate as an inverter and the active IGBT front power stage to operate as a rectifier. Transformer for a medium-voltage power converter according to one of the Claims 1 until 11 or after one of the Claims 12 until 14 , comprising: a plurality of core legs (815) arranged between a first column (811) and a second Column (812) are arranged in a suitable manner, wherein each of the plurality of core legs comprises: a set of segmented primary windings (816) arranged in a suitable manner adjacent to one another around the corresponding core leg; and a set of segmented secondary windings (818) arranged in a suitable manner adjacent to the set of segmented primary windings (816). Transformer according to Claim 15 wherein each of the plurality of core legs is associated with a phase of a three-phase power supply. Transformer according to Claim 16 wherein the set of segmented primary windings (816) for a first core leg is connected in parallel. Transformer according to Claim 15 wherein: each of a first set of segmented secondary windings (818) matingly disposed around the set of segmented primary windings (816) matingly disposed around a first core leg is coupled to one of a first power cube (240, 1100), the first power cube (240, 1100) comprising a low-frequency front-end stage, a DC intermediate circuit, and a high-frequency back-end stage, a second power cube (240, 1100) comprising a low-frequency front-end stage, a DC intermediate circuit, and a high-frequency back-end stage, and a third power cube (240, 1100) comprising a low-frequency front-end stage, a DC intermediate circuit, and a high-frequency back-end stage; each of a second set of segmented secondary windings (818) matingly disposed around the set of segmented primary windings (816) matingly disposed around a second core leg is coupled to one of the first power cube (240, 1100), the second power cube (240, 1100), and the third power cube (240, 1100); and each of a third set of segmented secondary windings (818) matingly disposed around the set of segmented primary windings (816) matingly disposed around a third core leg is coupled to one of the first power cube (240, 1100), the second power cube (240, 1100), and the third power cube (240, 1100). Transformer according to Claim 18 wherein the plurality of segmented secondary windings (818) provide a symmetrical impedance for the plurality of power cubes (240, 1100). Transformer according to Claim 18 wherein, to ensure mutual decoupling, each of the set of segmented primary windings (816) has a first separation distance of at least two inches from another of the set of segmented primary windings (816). Transformer according to Claim 20 wherein the plurality of segmented secondary windings (818) provide a portion of the symmetrical impedance for the plurality of power cubes (240, 1100) to ensure control stability. Transformer according to Claim 21 wherein each of the set of segmented primary windings (816) has a second separation distance of at least one-half inch from the set of segmented secondary windings (818). System comprising: a medium voltage power converter according to one of the Claims 1 until 11 or after one of the Claims 12 until 14 , comprising: a first cabinet (500) comprising: a power cube receptacle for receiving a plurality of power cubes (240, 1100), each of the plurality of power cubes (240, 1100) fitted within a respective housing and comprising a low-frequency front-end stage, a DC link, and a high-frequency back-end stage, the plurality of power cubes (240, 1100) being provided for coupling to a high-speed machine; a transformer receptacle having at least one transformer (230) for coupling between a supply terminal and the plurality of power cubes (240, 1100), the transformer receptacle including: a plurality of cooling fans (520) for cooling the at least one transformer (230); and wherein the at least one transformer (230) comprises: a plurality of core legs fitted between a first column and a second column, wherein: a first core leg has a first plurality of cooling plates fitted therein, a first set of segmented primary windings (816) fitted adjacent to one another around the first plurality of cooling plates, and a first set of segmented secondary windings (818) fitted around the first set of segmented primary windings (816); a second core leg has a second plurality of cooling plates fitted therein, a two th set of segmented primary windings (816) matingly disposed around the second plurality of cooling plates, and a second set of segmented secondary windings (818) matingly disposed around the second set of segmented primary windings (816); a third core leg has a third plurality of cooling plates matingly disposed therein, a third set of segmented primary windings (816) matingly disposed around the third plurality of cooling plates, and a third set of segmented secondary windings (818) matingly disposed around the third set of segmented primary windings (816). System according to Claim 23 , further comprising: a first cooling plate matingly disposed to at least a portion of the first column; and a second cooling plate matingly disposed to at least a portion of the second column. System according to Claim 23 , wherein the first cabinet (500) is sealed with respect to 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 is provided between the transformer receptacle and the power cube receptacle to ensure an exhaust air flow from the power cube receptacle to the transformer receptacle. System according to Claim 23 further comprising a plurality of first barriers adapted to direct an isolated first cooling air stream through one of the plurality of power cubes (240, 1100). System according to Claim 23 further comprising a first two-phase cooling system for cooling the at least one transformer (230) via the first, second and third plurality of cooling plates. System according to Claim 27 further comprising 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.

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