NL2019057B1

NL2019057B1 - AC to DC converter

Info

Publication number: NL2019057B1
Application number: NL2019057A
Authority: NL
Inventors: Gerardus Goedknegt Pieter; Everardus Antonius Van Der Heiden Robertus; Martin De Held Edwin
Original assignee: Orga Holding B V
Priority date: 2017-06-12
Filing date: 2017-06-12
Publication date: 2018-12-19
Also published as: EP3639357A1; WO2018231054A1; WO2018231054A8

Abstract

Between individual phases of a three-phase alternating current source, AC to DC converters are provided. The DC outputs of the converters are switched in parallel. The DC output may have the same effective voltage as the input, or higher or lower. The AC to DC converters preferably comprise electronic converters. The converters are provided in a steel of aluminium cabinet, preferably an explosion-safe cabinet. The switching components of the converters and other dissipating components are provided in thermal contact with one or more inner walls of the cabinet and at one or more outer walls of the cabinet, one or more heat sinks are provided. A module thus created provide a safe and flexible module for power supply on, for example, an offshore platform.

Description

TECHNICAL FIELD

The various aspects and embodiments thereof relate to a AC to DC converter, in particular to a three-phase AC to DC converter.

BACKGROUND

Conventional three-phase AC to DC converters employ transformers with wound coils for up or down conversion of a voltage, followed by a six-diode rectifier bridge and a capacitor for smoothing the output waveform.

With the arrival of power electronics, the three input phases are rectified and up or down conversion, followed by a buck or boost converter and an output filter for providing a smooth DC signal.

Whereas efficiency has gone up, AC to DC converters still are bulky devices that require significant cooling. This may be an issue in explosion safe environments. In explosion safe environments or explosion proof environments, a pressure-tight or flameproof cabinet, known as EX, is used. In the cabinet electronics and other equipment can be placed having a maximum, prescribed, power and heating development. Should there be an explosion inside of the cabinet, this explosion must remain inside of the cabinet. So, the flame or explosion must be cooled off on its way to the outside of the cabinet to ensure that the fire remains in the cabinet and cannot ignite the cabinet’s direct environment.

SUMMARY

It is preferred to provide an arrangement for converting three phase alternating current to direct current that is convenient to use.

A first aspect provides an arrangement for converting three phase alternating current having a first phase, a second phase and a third phase to direct current having a positive potential and a negative potential. The arrangement comprises a first phase input for receiving the first phase, a second phase input for receiving the second phase and a third phase input for receiving the third phase and a positive supply terminal and a negative supply terminal for providing direct current. The arrangement further comprises three alternating current to direct current converters. A first alternating current to direct current converter comprises a first input terminal connected to the first phase input, a second input terminal connected to the second phase input, a first positive output connected to the positive supply terminal and a first negative output connected to the negative supply terminal. A second alternating current to direct current converter comprises a first input terminal connected to the second phase input, a second input terminal connected to the third phase input, a second positive output connected to the positive supply terminal and a second negative output connected to the negative supply terminal. And a third alternating current to direct current converter comprises a first input terminal connected to the third phase input, a second input terminal connected to the first phase input, a third positive output connected to the positive supply terminal and a third negative output connected to the negative supply terminal.

By providing three single phase AC to DC converters, one provided between each pair of distinct phases, smaller components may be used compared to three phase AC to DC converters in which the three phases are rectified and one large DC to DC converter is used for down or up conversion. Use of smaller components may be employed for improved removal of dissipated heat, as smaller components have a higher outer surface/volume ratio compared to larger components. The smaller components also allows for smaller building form factors and smaller footprint. Firstly in view of the size of the components and secondly in view of reduced requirements with respect to removal of heat.

Furthermore, such system may be cheaper in maintenance. An important reason for this is that in case of failure, only one - smaller - single phase AC to DC converter may be replaced, instead of a larger three-phase component. The replacement may be physically, by taking a malfunctioning device out of the arrangement and replacing it by a new device. Alternatively, the replacement may be functionally, by shutting down the malfunctioning device and using another AC to DC converter switched in parallel to the malfunctioning device.

In an embodiment, the alternating current to direct current converters comprise switched power converters comprising solid state switches. Such switches and switches comprising silicon carbide or silicon active parts in particular, allow for efficient switching of power. Such switches may be MOSFETs, IGBTs, Triacs, other, or a combination thereof. Switches having a low or negligible switching current - like MOSFETs are preferred. Advantageously, the switched power converter has an operating frequency between about 40 kHz and about 60 kHz, preferably at about 45 kHz

An embodiment of the arrangement comprises a cabinet predominantly comprising metal, like (stainless) steel or aluminium, wherein the alternating current to direct current converters are provided in the cabinet such that the solid state switches are placed in thermal contact with an inner side of a first wall of the cabinet. Advantageously, the electric components, amongst which the solid state switches, are placed in direct thermal contact with a wall of the cabinet to improve heat dissipation. In an embodiment, het electronic components are mounted onto a wall of their casing, which in turn, is mounted in direct thermal contact with the wall of the cabinet to provide for heat dissipation to the outside of the cabinet.

In this embodiment, the cabinet may be used as a heat sink. If more heat removal capacity is required, the heatsink may be extended, for example, the heatsink may further comprise cooling fins, may be provided, preferably at an opposite side of the heatsink. This allows for static cooling and may remove the need for forced air cooling. This, in turn, provides more reliable operation. If the arrangement is to be used in high-reliability environments, like off-shore platforms, such reliability is very important. Furthermore, closed cabinets known so far and explosion safe cabinets in particular usually prevent proper removal of heat generated within the cabinet, as convection is not a reliable option and explosion safe cabinets are pressure-tight or flameproof, e.g. as required by regulation IEC-60079-1. On the other hand, this embodiment with semiconductor devices in direct thermal contact with the wall of the cabinet, improved heat removal is provided.

In this embodiment, the alternating current side of the converters are galvanically isolated from the direct current side of the converters. This allows for safer operation at the secondary side, where overload or other potential causes for malfunction, will not always and/or directly result in failure at the primary side. Such isolation may be provided by employing a forward based converter in the AC to DC converters.

A second aspect provides a system for converting three phase alternating current having a first phase, a second phase and a third phase to direct current having a positive potential and a negative potential, the system comprising a plurality of arrangements according to the first aspect connected in parallel at the input and at the output. By providing a plurality of arrangements, the system can relatively easily be scaled up, or down, depending on the power requirements. This provides for a modular system that can be tailored to the requirements defined by an operator and/or regulations.

An embodiment of this system further comprises a control circuit. The control circuit can be arranged to detect malfunction of an alternating current to direct current converter of a first of a first arrangement and a second arrangement and control a further alternating current to direct current converter of a second of the first arrangement and the second arrangement, parallel to the malfunctioning alternating current to direct current converter, to take over functionality of the malfunctioning alternating current to direct current converter in the first of the first arrangement and the second arrangement. Advantageously, the control circuit is mainly configured to detect malfunction of a converter and to rearrange the arrangement with a functioning, e.g. redundant or spare, converter.

Such system provides efficient redundancy in case of failure of a single phase AC to DC converter. Rather than replacing a full three phase converter arrangement, only a single converter is replaced. This improves the flexibility of the system and may reduce downtime as well as maintenance cost. For example, in case one converter fails, a second, redundant, converter can take over the functionality of the failed first converter. Then, the first converter may be replaced by a different, functioning converter and/or may be repaired without impairment to the functioning of the system, thus reducing downtime.

Advantageously, each AC to DC converter may be provided individually, either fully or partially, in a casing, a so-called converter module. Thus, to provide an arrangement with three alternating current to direct current converters, three converter modules are used for the arrangement. The converter module comprises the required electronic components to provide for the alternating current to direct current conversion, for example a power factor correction circuit - PFCC, a voltage converter and an output filter. Other and/or additional components may be provided in the converter module as well.

Further, each converter module comprises an input for alternating current, an output for direct current. Providing such a converter module is advantageous for manufacturing, installation, repair and/or maintenance.

The converter modules can be manufactured in a controlled environment, such as a manufacturing hall, where they can be tested and controlled prior to leaving the factory. So, the converter module can be installed as a whole to form the arrangement, only connections to input, output. This allows easy installation and reduces the risk on mistakes and/or failures.

Also, in case of failure, the converter module can be easily removed from the arrangement and replaced by an other, functioning, converter module for which also only connections to input, output. This may allow for a cost reduction during the lifetime of the system. Advantageously, the casings of the converter modules may have at least the same footprint and/or may have the same shape. As such, the converter modules are more easily interchangeable with one another.

A connection between a converter module and an other and/or adjacent converter module can be established via the control circuit.

Preferably, the arrangement comprises a cabinet, so the three converter modules forming the arrangement can be mounted in the cabinet, advantageously an explosion proof cabinet. The cabinet may be provided with seats corresponding with a footprint of the converter module, allowing for more easy mounting of the converter modules in the cabinet.

The invention further relates to a system for converting three phase alternating current comprising a plurality of the arrangements. This provides for relatively easy scaling up, e.g. when more current output is required. When converter modules are used, simply additional converter modules can be mounted to the system and can be connected to each other to provide for an arrangement of converters. In an embodiment comprising a cabinet, scaling up can be done relatively easy by providing one or more additional cabinets. The plurality of arrangements, for example a plurality of cabinets, can then be connected to each other to form a larger system for alternating current to direct current conversion. Scaling down of the system can of course be done as well.

Further advantageous embodiments are explained in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The various aspects and embodiments thereof will now be discussed in further detail in conjunction with drawings. In the drawings:

Figure 1: shows an three-phase AC to DC converter;

Figure 2: shows a graph depicting normalized voltage or current amplitude vs. time for various nodes in the three-phase AC to DC converter;

Figure 3: shows a single phase AC to DC converter

Figure 4: shows an explosion safe cabinet with the threephase AC to DC converter; and

Figure 5: shows a compound three-phase AC to DC converter.

DETAILED DESCRIPTION

Figure 1 shows a power supply system 100. The power supply system 100 comprises an alternating current to direct current - AC-DC converting system 150 as an embodiment of the arrangement according to the first aspect and a three phase generator 110 as an alternating current electric energy supply. The generator 110 comprises a first excitation winding 112, a second excitation winding 114 and a third excitation winding 116. The three excitation windings provide alternating current in three phases, each 2/3 n rad or 120° apart in phase.

In Figure 1, the three phase generator 110 is schematically shown in star configuration. Optionally, the centre of the star may be connected to earth. Alternatively, the three phase generator 110 may be provided in a delta configuration. The power supply system 100 may be used for charging batteries for uninterrupted power supplies. Such uninterrupted power supplies may be found in power-critical environments, like data centres, offshore exploration platforms or other systems that require reliable power. Alternatively or additionally, the power supply system 100 may be used for powering further equipment like lighting, heating, electromotors or other actuators, other, or a combination thereof.

The AC to DC converting system 150 comprises a first alternating current to direct current converter 300, a second alternating current to direct current converter 300' and a third alternating current to direct current converter 300. The AC to DC converters each comprise an input for receiving an alternating current power supply and an output 154 for providing a direct current supply. The AC to DC converting system 150 further comprises a control module 152 for controlling the operations of the AC to DC converters.

The voltage at the output 154 may be the substantially the same as the effective voltage provided by the three phases of the three phase generator 110, substantially higher or substantially lower. Also the current provided by the output 154 may be the substantially the same as the effective current provided by the three phases of the three phase generator 110, substantially higher or substantially lower. The output power available at the output 154 is preferably as close as possible to the power provided by the three phase generator 110.

The AC to DC converters are connected between two phases provided by the three phase generator 110. This means that neither input terminal of each AC to DC converter has a fixed potential relative to ground. This is elucidated by Figure 2. Figure 2 shows a graph 200 with waveforms of normalized amplitudes of voltages at various locations in the power supply system 100. Alternatively, they may represent normalized currents. The y-axis represents normalized values and the values at the horizontal axis are in radials. The lines Φ1, Φ2, Φ3 provide voltage levels over each of the windings 112, 114, 116 of the three phase generator 110. The lines Θ1, Θ2, Θ3, provide voltage levels at each of the inputs of the AC to DC converters 300, 300’, 300”. Θ1 represents the difference between the voltages Φ1 and Φ2. Θ2 represents the difference between the voltages Φ2 and Φ3. Θ3 represents the difference between the voltages Φ3 and Φ1. The AC-DC converters 300, 300’, 300” then convert this input AC voltage to an output DC voltage 154.

From the graph 200 in figure 2, it may be deduced that the amplitude of the signals Θ1, Θ2, 03provided at the inputs of the AC to DC converters is proportional to the amplitude of the voltages over the windings Φ1, Φ2, Φ3 with a factor of cube root, in view of the three-phase generator 110.

The amplitude of the signals Φ1, Φ2, ®3at the windings 112, 114, 116 are each 2/3 n rad or 120° apart in phase, as well known for a threephase generator. As a consequence, also the amplitude of the signals Θ1, Θ2, Θ3 at the input of the convertors 300, 300’, 300” are each 2/3 n rad or 120° apart in phase. Also, the input signals Θ1, Θ2, Θ3 are having a phase difference with respect to the winding signals Φ1, Φ2, Φ3 due to their nature of representing a difference between the connected winding signals. A phase lag or lead of one or more of the phases will lead to higher or lower amplitudes at the inputs of the AC to DC converters. Therefore, the components of the AC to DC converters are preferably dimensioned such that they are able to withstand such fluctuations of amplitudes at the input side. Alternatively or additionally, the control module 152 is arranged to compensate for the phase changes of the input phases.

Figure 3 shows the first AC to DC converter 300 in further detail. The first AC to DC converter 300 comprises a power factor correction circuit - PFCC - 310, a voltage converter 320 and an output filter 330. Further, an input filter and a mains rectifier may be provided between the input 302 and the PFCC 310. An alternating current - or alternating voltage - signal is provided at an input 302 of the first AC to DC converter 300. The signal is firstly filtered by an EMC filter, and rectified by a mains rectifier to obtain a DC signal. This DC signal is offered to the PFCC 310 for correcting the power factor. The PFCC 310 works on a constant frequency and may comprise electronic components such as switch transistors or rectifier diodes. Further, to obtain a longer lifetime of the power factor correction circuit 310, a metal film condensator may be used as storage condensator, such that electrolytes can be obviated. This makes the PFCC more reliable and allows for a longer lifetime.

With the voltage converter 320 comprising various reactive components, including capacitors and/or inductances, voltage and current at the left side of the voltage converter 320 may not always be in phase. This is not preferred, as this may put a high strain on the three phase generator 110. The PFCC 310 is arranged to reduce and preferably minimize the difference in phase between voltage and current at the input 302. The PFCC may comprise first semiconductors switches 312.

In the voltage converter 320, an input voltage is converted down in this embodiment. In the examples discussed in this application, the input voltage has an amplitude of 340 Volt per phase - 240 Volt RMS - and preferably has a frequency between approximately 48 Hz and approximately 62 Hz, with a target frequency of about 50 Hz or about 60 Hz. In other embodiments, the amplitude may be higher. In further embodiments, a transformer or additional voltage converter may be provided between the three phase generator 110 and the AC-DC converting system 150. The voltage converter 320 preferably comprises a switched circuit for the voltage conversion, rather than a conventional transformer. In a preferred embodiment, the voltage converter 320 comprises forward converter, comprising second semiconductor switches 322. Advantageously, the converter 320 is an isolated full bridge forward converter with silicon carbide transistors. The converter can be controlled by a converter controller, which may be provided in a controller module, as discussed later.

The second semiconductor switches 322 are preferably field effect transistors, also known as FET, comprising silicon carbide and/or a gate comprising a material having a low dielectric constant. Such field effect transistors are available having a very low channel resistance. The second semiconductor switches 322 of the converter 320 preferably operate at a frequency between about 40kHz and about 60kHz, with a preferred frequency of approximately 45kHz. Whereas the second semiconductor switches 322 are referred to as a multiple, some embodiments may employ only one field effect transistor or other semiconductor switch in the voltage converter 320.

An advantage of use of a forward converter is that it is generally more efficient than a forward based converter. Further, the primary side and the secondary side are galvanically separated by means of a transformer. Whereas use of transformers is not preferred at frequencies between about 48 Hz and about 62 Hz due to the inefficiencies of transformers in that frequency range, transformers having a ferrite core provide high efficiency operation at frequencies between about 40kHz and about 60kHz.

The supply signal provided at the output of the voltage converter 320 is provided to the output filter 330. Between the converter 320 and the output filter 330, a rectifier can be provided. Such a rectifier can rectify the signal outputted by the converter 320 before supplying it to the output filter 330. The rectifier comprises active transistors, instead of passive diodes, to improve the efficiency of the rectifier. Alternatively, the rectifier may be implemented in front of the output filter. The output filter 330 may comprise various reactive elements for providing a smooth constant level of a DC power supply signal to an output of the first AC to DC converter 300. The output signal is preferably provided at approximately 24 Volt, with a maximum current of about 75 Ampère. With three AC to DC converters 300, 300’, 300” provided in parallel, one for each phase, the AC to DC converting system 150 may provide a current of up to approximately 225 Ampère and may be rated at about 200 Ampère at continuous operation - at approximately 4,8 kW.

Whereas the channel resistance is relatively low - in the order of milli-Ohms or even tenths thereof -, the semiconductor switches still dissipate an amount of thermal energy that needs to be removed from the switches in particular and the AC to DC converter 300 in particular. An environment that is too hot quickly reduces life expectancy and/or performance of components , so removing the heat is very important.

As discussed above, the AC to DC converting system 150, as an embodiment of the arrangement according to the invention, is preferably used at an off-shore exploration platform. Such exploration platforms have strict requirements with respect to explosion safety. One important requirement is that electrical circuits are provided in a closed box or cabinet that is sealed in accordance with a particular standard. Hence, direct cooling of semiconductor devices by means of conventional measures convection of air - is not possible.

Figure 4 shows an explosion safe cabinet 400 comprising the AC to DC converting system 150. The explosion safe cabinet 400 comprises a compartment 410 and a door 420. The door 420 is connected to the compartment 410 by means of hinges or other elements enabling to move the door 420 to open the compartment 410. The door and/or the compartment 410 may be provided with seals for providing a pressure-tight or flameproof space in the cabinet 400 with the door 420 closed. Sealing may be provided in well known manners for EX-cabinets, such as using plane flanges or O-rings. To that purpose, the door 420 may be bolted to the compartment 410. Furthermore, the compartment 410 and the door 420 predominantly comprise a metal or a metal alloy, like aluminium or stainless steel. Figure 4 gives a very schematic representation, and is to be understood that the converters 300, 300’, 300” are mounted to the cabinet 400, in particular to the cabinet back wall 412 with fastening elements, such as screws or bolts, or even may be welded to the back wall 412 or otherwise may be thermally connected to the back wall 412. Also, the door 420 may be provided with well known closing elements for providing an explosion proof closure of the cabinet 400. Also, in view of the schematic representation in figure 4, it is to be understood that the first and the second semiconductor switches 312, 322 are physically mounted in the converter 300, 300’, 300”.

In the compartment, the first AC to DC converter 300, the second AC to DC converter 300' and the third AC to DC converter 300 are provided. The AC to DC converters 300, 300’, 300” may be provided in the compartment 410 as fixed components, in which embodiment the output terminals of the individual converters are rigidly fixed to, for example, two common conductor rails that provide the DC output 154 (Figure 1) of the AC to DC converting system 150. In an alternative embodiment, the individual AC to DC converters are releasably mounted in the compartment 410, preferably in individual casings, that allow fast, convenient and efficient replacement of individual AC to DC converters.

The AC to DC converters 300, 300’, 300” are placed in the compartment 410 such that they have a thermally conductive connection with a back wall 412 of the compartment 410. More in particular, the first semiconductor switches 312 and the second semiconductor switches 322 are placed in the compartment 410 such that they have a thermally conductive connection with a back wall 412 of the compartment 410. The cabinet is further provided with a heatsink 430. The heatsink 430 comprises in this embodiment, the back wall 412 of the compartment 410.

The heatsink 430 further comprises fins 432 for radiating thermal energy. The heatsink 430 is in thermal contact with the back wall 412 and is preferably provided over at least most of the area of the back wall 412. In an embodiment, the heatsink 430 comprises the back wall 412 and the fins 432 connected thereto. In this way, the heatsink 430 is in thermal contact with the first semiconductor switches 312 and the second semiconductor switches 322 for radiating thermal energy dissipated by these switches. If the heat radiation capacity of the back wall 412 is sufficient to ensure proper operation of the AC to DC system 150, the back wall 412 may be sufficient as the heatsink 430, and the fins 432 may be omitted. Alternatively, the heat sink may comprise a plate that is mounted to the back wall, at an outer side thereof, with, if required, fins connected to the plate. Many variants are possible.

Advantageously, the electric components of the arrangement 150 and of the converters 300, 300’, 300” are mounted directly onto the back wall 412 of the cabinet 410, preferably with limited or preferably no additional thermally conductive layers in between. In another embodiment, the electric components of the converters 300, 300’, 300” are mounted onto a back wall of their individual casing, which casing is mounted directly onto a wall, advantageously the back wall, of the cabinet 410. Advantageously, the footprint of the casing fits into a seat of the back wall such that a tight mounting is possible to improve the heat transport. As such, heat can be transported directly to the outside of the cabinet, while reducing the number of thermally conductive layers. Advantageously, to improve the heat dissipating capacity, the heat sink 430 may additionally be provided with fins 432 extending outwardly from the back wall 412.

Likewise, semiconductor switches and/or other semiconductor components of the second AC to DC converter 300' and the third AC to DC converter 300 are thermally conductively connected to the heatsink 430 via the back wall 412. Alternatively to the back wall 412, the heatsink 430 may be provided on another wall of the compartment 410 - as long as an efficient thermal connection with the relevant semiconductor circuit elements is provided.

For practical purposes, in particular with respect to cabinet size, individual converters (300, 300', 300) providing a current of 75 Ampère may be preferred - providing a total maximum current of about 200 Ampère per AC to DC system 150 as depicted by Figure 1. Systems for providing larger currents require larger cabinets, in particular considering heat dissipation and heat sink requirements. For loads requiring a higher current, multiple arrangements may be provided in parallel. Figure 5A shows the three phase generator 110 connected to a compound AC to DC converting system 500.

The compound system 500 comprises a first AC to DC arrangement or converting system 150, a second AC to DC arrangement or converting system 156 and a third AC to DC arrangement or converting system 158. Each AC to DC converting system is preferably provided in a separate explosion safe cabinet. The first AC to DC converting system 150 comprises a first AC to DC converter 300, a second AC to DC converter 300’ and a third AC to DC converter 300. The second AC to DC converting system 150' comprises a fourth AC to DC converter 306, a fifth AC to DC converter 306' and a sixth AC to DC converter 306. The third AC to DC converting system 150 comprises a seventh AC to DC converter 308, a eighth AC to DC converter 308' and a ninth AC to DC converter 308. The compound system 500 further comprises a system module 502 for controlling the various components of the compound system 500.

In this embodiment, the compound system 500 is designed such that the first AC to DC converting system 150 and the second AC to DC converting system 150' operate parallel to one another for providing approximately 400 Ampère maximum, at 24 Volts: 9.6 kW. Other values of voltage, current and power may be envisaged was well. The third AC to DC converting system 150 is arranged to be available in standby, as a redundant module. In this embodiment, the seventh AC to DC converter 308, the eighth AC to DC converter 308' and the ninth AC to DC converter 308 are designed as separate redundant module.

The redundancy principle is further elucidated by Figure 5 B. In Figure 5 B, the second AC to DC converter 300' is depicted as malfunctioning. Hence, from the first and third phase provided by the three phase generator 110, about 150 Ampère may be provided, but from the second phase only 75 Ampère. This may lead to imbalance of the three phase generator 110 and/or overload of the fifth AC to DC converter 306'. Alternatively, the control module 502 switches the compound system 500 to secure mode, in which only half the amount of power may be provided.

As all of these three situations are all but preferred, the third AC to DC converting system 150 is arranged to be available in standby, as a redundant module. With the second AC to DC converter 300' failing, the eighth AC to DC converter 308' is switched on, controlled by the control module 502 that detects failure of the second AC to DC converter 300'. In this way, the compound system 500 can still provide the 9.6 kW power for which it has been designed.

In another embodiment, all individual AC to DC converters are operational and the maximum current to be provided by the individual AC to DC converters is limited below the actual maximum current they can provide. Such limitation may be controlled by means of the controller module 502. For example, the individual AC to DC converters may be operational at 80% of their operational power. In case of failure of one converter module, the remaining converter modules may then become operational at 100% of their power.

More in particular, the amount by which current supplied the individual AC to DC converters may be determined based on the total amount of individual AC to DC converters available per phase. If in total five individual AC to DC converters are available per phase, the maximum current to be provided may be set at 20% below the maximum current that each individual AC to DC converter can provide. In this way, if one individual AC to DC converter fails, the current initially provided by the malfunctioning or failing individual AC to DC converter may be taken over by the other four AC to DC converters available on that particular phase.

In summary, an AC to DC conversion system is disclosed, whereof between individual phases of a three-phase alternating current source, AC to DC converters are provided. The DC outputs of the converters are switched in parallel. The DC output may have the same effective voltage as the input, or higher or lower. The AC to DC converters preferably comprise electronic converters. In particular a forward based converter is preferred, as it provides a galvanic separation between the input side and the output side of the converter. The converters are provided in a steel or aluminium cabinet, preferably an explosion-safe cabinet. The switching components of the converters and other dissipating components are provided in thermal contact with one or more inner walls of the cabinet and at one or more outer walls of the cabinet, one or more heat sinks are provided. A module thus created provide a safe and flexible module for power supply on, for example, an offshore platform.

In the description above, it will be understood that when an element such as layer, region or substrate is referred to as being “on” or “onto” another element, the element is either directly on the other element, or intervening elements may also be present. Also, it will be understood that the values given in the description above, are given by way of example and that other values may be possible and/or may be strived for.

Furthermore, the invention may also be embodied with less components than provided in the embodiments described here, wherein a single component carries out multiple functions. Just as well may the invention be embodied using more elements than depicted in the Figures, wherein functions carried out by one component in the embodiment provided are distributed over multiple components.

It is to be noted that the figures are only schematic representations of embodiments of the invention that are given by way of non-limiting examples. For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.

The word ‘comprising’ does not exclude the presence of other features or steps than those listed in a claim. Furthermore, the words 'a' and 'an' shall not be construed as limited to 'only one', but instead are used to mean 'at least one', and do not exclude a plurality.

A person skilled in the art will readily appreciate that various parameters and values thereof disclosed in the description may be modified and that various embodiments disclosed and/or claimed may be combined without departing from the scope of the invention.

It is stipulated that the reference signs in the claims do not limit the scope of the claims, but are merely inserted to enhance the legibility of 15 the claims.

Claims

ConclusiesConclusions

1. Inrichting voor het converteren van drie-fasen wisselstroom met een eerste fase, een tweede fase en een derde fase naar gehjkstroom met een positief potentiaal en een negatief potentiaal, waarbij de inrichting omvat:A device for converting three-phase alternating current with a first phase, a second phase and a third phase into a currents current with a positive potential and a negative potential, the device comprising:

- een eerste fase-ingang voor het ontvangen van de eerste fase, een tweede fase-ingang voor het ontvangen van de tweede fase en een derde fase-ingang voor het ontvangen van de derde fase;- a first phase input for receiving the first phase, a second phase input for receiving the second phase and a third phase input for receiving the third phase;

- een positieve toevoeraansluiting en een negatieve toevoeraansluiting voor het verschaffen van gelijkstroom;- a positive supply connection and a negative supply connection for supplying direct current;

- een eerste wisselstroom naar gelijkstroom omvormer omvattende een eerste ingangsaansluiting verbonden met de eerste fase-ingang, een tweede ingangsaansluiting verbonden met de tweede fase-ingang, een eerste positieve uitgang verbonden met de positieve toevoeraansluiting en een eerste negatieve uitgang verbonden met de negatieve toevoeraansluiting;a first AC to DC converter comprising a first input terminal connected to the first phase input, a second input terminal connected to the second phase input, a first positive output connected to the positive supply terminal and a first negative output connected to the negative supply terminal;

- een tweede wisselstroom naar gelijkstroom omvormer omvattende een eerste ingangsaansluiting verbonden met de tweede fase ingang, een tweede ingangsaansluiting verbonden met de derde fase-ingang, een tweede positieve uitgang verbonden met de positieve toevoeraansluiting en een tweede negatieve uitgang verbonden met de negatieve toevoeraansluiting;- a second AC to DC converter comprising a first input terminal connected to the second phase input, a second input terminal connected to the third phase input, a second positive output connected to the positive supply terminal and a second negative output connected to the negative supply terminal;

- een derde wisselstroom naar gelijkstroom omvormer omvattende een eerste ingangsaansluiting verbonden met de derde fase ingang, een tweede ingangsaansluiting verbonden met de eerste fase-ingang, een derde positieve uitgang verbonden met de positieve toevoeraansluiting en een derde negatieve uitgang verbonden met de negatieve toevoeraansluiting.a third AC to DC converter comprising a first input terminal connected to the third phase input, a second input terminal connected to the first phase input, a third positive output connected to the positive supply terminal and a third negative output connected to the negative supply terminal.

2. Inrichting volgens conclusie 1, waarbij de wisselstroom naar gelijkstroom omvormers schakelende voedingsomvormers omvatten die halfgeleiderschakelaars omvatten.The device of claim 1, wherein the AC to DC converters comprise switching power converters comprising semiconductor switches.

3. Inrichting volgens conclusie 2, waarbij ten minste enkele van de halfgeleiderschakelaars siliciumcarbide veldeffecttransistoren en/of siliciumcarbide diodes zijn.The device of claim 2, wherein at least some of the semiconductor switches are silicon carbide field effect transistors and / or silicon carbide diodes.

4. Inrichting volgens conclusie 2 of 3, verder omvattende een kast die hoofdzakelijk een metaal omvat, waarbij de wisselstroom naar gelijkstroom omvormers zijn voorzien in de kast zodanig dat de halfgeleiderschakelaars in contact zijn geplaatst met een binnenzijde van een eerste wand van de kast.The device of claim 2 or 3, further comprising a cabinet comprising mainly a metal, the AC to DC converters provided in the cabinet such that the semiconductor switches are placed in contact with an interior of a first wall of the cabinet.

5. Inrichting volgens conclusie 4, waarbij de kast een ontploffingsveilige kast is.The device according to claim 4, wherein the box is an explosion-proof box.

6. Inrichting volgens conclusie 4 of conclusie 5, waarbij de kast een koellichaam aan een buitenzijde van de eerste wand omvat.The device of claim 4 or claim 5, wherein the cabinet includes a heat sink on an exterior of the first wall.

7. Inrichting volgens één der conclusies 1 - 6, waarbij de wisselstroomzijde van de omvormers galvanisch is geïsoleerd van de gelijkstroomzijde van de omvormers.The device according to any one of claims 1 to 6, wherein the AC side of the inverters is galvanically isolated from the DC side of the inverters.

8. Inrichting volgens conclusie 7, waarbij de wisselstroom naar gelijkstroom omvormers een forward omvormer omvat.The device of claim 7, wherein the AC to DC converters comprise a forward converter.

9. Inrichting volgens één der conclusies 2-8, waarbij de schakelende voedingsomvormer een werkingsfrequentie tussen ongeveer 40 kHz en ongeveer 60 kHz heeft, bij voorkeur rond 45 kHz.The device of any one of claims 2-8, wherein the switching power converter has an operating frequency between about 40 kHz and about 60 kHz, preferably about 45 kHz.

10. Inrichting volgens één der conclusies 1-9, ingericht om een gelijkstroomresultaat van ongeveer 200 Ampère bij nagenoeg 24 Volt te verschaffen.The device of any one of claims 1 to 9, arranged to provide a DC result of about 200 amps at substantially 24 volts.

11. Systeem voor het om vormen van drie fasen wisselstroom met een eerste fase, een tweede fase en een derde fase naar gelijkstroom met een positief potentiaal en een negatief potentiaal, waarbij het systeem een veelvoud omvat aan inrichtingen volgens conclusies 1 - 9 die aan de ingang en aan de uitgang parallel zijn verbonden.System for converting three-phase alternating current with a first phase, a second phase and a third phase into direct current with a positive potential and a negative potential, the system comprising a plurality of devices as claimed in claims 1 to 9 input and output are connected in parallel.

12. Systeem volgens conclusie 11, verder omvattende een sturingscircuit dat is in gericht om:The system of claim 11, further comprising a control circuit arranged to:

- een storing te detecteren van een wisselstroom naar gelijkstroom omvormer van een eerste van een eerste inrichting en een tweede inrichting;- detecting a failure of an AC to DC converter from a first of a first device and a second device;

- een verdere wisselstroom naar gelijkstroom omvormer van een tweede van de eerste inrichting en de tweede inrichting aan te sturen die parallel is aan de gestoorde wisselstroom naar gelijkstroom omvormer, om de functionaliteit van de gestoorde wisselstroom naar gelijkstroom omvormer over te nemen in de eerste van de eerste inrichting en de tweede inrichting.- controlling a further alternating current to direct current converter from a second of the first device and the second device parallel to the disturbed alternating current to direct current converter, to take over the functionality of the disturbed alternating current to direct current converter in the first of the first device and the second device.

13. Systeem volgens conclusie 12, waarbij de tweede van de eerste inrichting en de tweede inrichting is voorzien als een reserve-inrichting.The system of claim 12, wherein the second of the first device and the second device is provided as a backup device.

14. Systeem volgens conclusie 12, waarbij de werking van gestoorde wisselstroom naar gelijkstroom omvormer van de eerste van de eerste inrichting en de tweede inrichting is verdeeld over een veelvoud van wisselstroom naar gelijkstroom omvormers die parallel zijn aan deThe system of claim 12, wherein the operation of aided AC to DC converter of the first of the first device and the second device is distributed over a plurality of AC to DC converters parallel to the

5 gestoorde wisselstroom naar gelijkstroom omvormer.5 disturbed alternating current to direct current converter.

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