NO343384B1 - Device for providing galvanic isolation in an AC power supply to a marine vessel - Google Patents
Device for providing galvanic isolation in an AC power supply to a marine vessel Download PDFInfo
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- NO343384B1 NO343384B1 NO20171852A NO20171852A NO343384B1 NO 343384 B1 NO343384 B1 NO 343384B1 NO 20171852 A NO20171852 A NO 20171852A NO 20171852 A NO20171852 A NO 20171852A NO 343384 B1 NO343384 B1 NO 343384B1
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- power supply
- marine vessel
- capacitor
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- assembly
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- 238000002955 isolation Methods 0.000 title claims abstract description 66
- 239000003990 capacitor Substances 0.000 claims abstract description 81
- 238000004146 energy storage Methods 0.000 claims description 21
- 230000036541 health Effects 0.000 claims description 4
- 238000012544 monitoring process Methods 0.000 claims description 4
- 238000004804 winding Methods 0.000 description 4
- 230000033228 biological regulation Effects 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 230000001105 regulatory effect Effects 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 230000000712 assembly Effects 0.000 description 2
- 238000000429 assembly Methods 0.000 description 2
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- 238000006243 chemical reaction Methods 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000013535 sea water Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
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- 239000000446 fuel Substances 0.000 description 1
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- 238000005259 measurement Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2200/00—Type of vehicles
- B60L2200/32—Waterborne vessels
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63J—AUXILIARIES ON VESSELS
- B63J3/00—Driving of auxiliaries
- B63J3/04—Driving of auxiliaries from power plant other than propulsion power plant
- B63J2003/043—Driving of auxiliaries from power plant other than propulsion power plant using shore connectors for electric power supply from shore-borne mains, or other electric energy sources external to the vessel, e.g. for docked, or moored vessels
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T70/00—Maritime or waterways transport
- Y02T70/50—Measures to reduce greenhouse gas emissions related to the propulsion system
- Y02T70/5218—Less carbon-intensive fuels, e.g. natural gas, biofuels
- Y02T70/5236—Renewable or hybrid-electric solutions
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02T90/10—Technologies relating to charging of electric vehicles
- Y02T90/12—Electric charging stations
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Power Engineering (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Rectifiers (AREA)
Abstract
Device (10) for providing galvanic isolation in a power supply to a marine vessel, wherein the device (10) is connected to an AC power supply (50) at one side and to a consumer network (60) at the other side, wherein the device (10) includes a rectifier assembly (20) comprising at least two stacks (21a-c) of at least two diodes (22), wherein the at least two stacks (21) of diodes (22) are arranged in parallel to each other, wherein the device (10) further comprises a capacitor assembly (30) comprising at least two capacitors (31a-c) or capacitor units (32a-c), wherein respective capacitor (31a-c) or capacitor unit (32ac) of the capacitor assembly (30) is arranged in series between respective phase of the AC power supply (50) and an associated stack (21a-c) of diodes (22) in the rectifier assembly (20).
Description
Device for providing galvanic isolation in an AC power supply to a marine vessel
The present invention is related to a device for providing galvanic isolation in an alternating current (AC) power supply to a marine vessel, according to the preamble of claim 1.
The present invention is especially related to a device for providing galvanic isolation between an AC power supply side and a marine vessel by providing a galvanically isolated AC/DC rectifier at the marine vessel side.
Background
At present there is great interest within the marine industry to develop environmentally friendly propulsion systems for marine vessels, where the main goal is to achieve zero emissions or close to zero emissions from the marine vessel. Electric and hybrid electric (electric and fuel) propulsion systems are increasingly being used. Such systems enable the marine vessel to be driven entirely or in part by electrical energy stored in energy storage devices.
Many of modern marine vessels, e.g. ferries, have a DC (direct current) distribution system connected with the energy storage devices.
To utilize the energy from the energy storage a DC power consumer must be connected to the energy storage.
In order to charge the energy storage device the marine vessel requires a power conversion stage, converting from a low-voltage AC grid supply to DC voltage.
Where two systems such as a marine vessel and a (harbour) power supply grid have separate grounds, the grounds would normally be connected during charging to be able to handle faults, such as ground fault on the vessel. In the marine industry however creating an electrical connection between a marine vessel and the shore (and inherently other marine vessels in the harbour) can give rise to corrosion of submerged metallic parts. Different metals have different electric potentials when exposed to an electrolyte like seawater; so when the electric grounds are connected, these materials are electrically connected and a circuit is formed permitting a galvanic current to flow through the electrolyte (seawater) leading to corrosion.
Removing the ground connection to prevent this corrosion is not a suitable solution as this may introduce electrical hazards. For example, if a ground fault were to occur on a marine vessel with such a grounding configuration, the power supply protection might not trip and the fault current would continue flow into the fault circuit.
There are two prior art solutions for isolating galvanic currents without impacting the electrical safety of the power system.
The first solution is to use an isolation transformer on the AC power supply. In this solution, a metal shield separates the windings and this shield is connected to the ground of the (harbour) power supply grid. In this case, earth fault current on the primary side will flow back to the electrical protection of the power supply grid. For the secondary winding, the ground of the marine vessel is connected to the neutral. This mimics the configuration of electrical transmission networks and allows electrical protection to be implemented on the marine vessel. Importantly, the primary and secondary windings of the isolation transformer are only magnetically coupled, so there is no electrical connection that will permit galvanic currents.
An example of this solution is known from US2011298283 which describes an electrical supply system that incorporates transformers at the power supply (quay) side to provide galvanic isolation.
The main disadvantages of using isolation transformers are power transfer loss, the weight and cost of implementing them on marine vessels.
The second solution is to use a galvanic isolator. This is simply a diode circuit placed between the power supply grid and marine vessel grounds. The diodes will only pass electrical current when the forward voltage is exceeded, so the diodes are rated to be greater than the expected voltage differential between dissimilar metals. Therefore, if a fault occurs on the marine vessel, the fault current will be able to flow through the ground connection back to the power supply grid electrical protection, but galvanic currents will not flow.
An example of this solution is known from US7817055 which describes an implementation of such a galvanic isolator in the form of a charging adaptor.
The disadvantage with galvanic isolators is that modern equipment contains switch mode power supplies that require capacitive connections to ground to remove Radio Frequency (RF) noise. These capacitive connections allow AC current to leak to the ground connection with the impedance of the capacitor decreasing as AC frequency increases. With sufficient voltage, this rejected RF noise can forward bias to the galvanic isolator thus removing the galvanic isolation. To work around this, some solutions like the one described in US7817055 add a capacitor in parallel with the diodes to provide a current path for this AC current. However, with numerous devices rejecting the RF noise in a single system, there is a limit to what size capacitor can be implemented whilst keeping the AC voltage below the diode forward bias voltage. Additionally, a galvanic isolator does not offer power conversion functionality, so additional hardware would be required to convert from supply AC to marine vessel DC distribution voltage.
EP 2528233 A1 discloses a device for providing galvanic isolation in a power supply, wherein the device is connected to an AC power supply at one side and to a consumer network at the other side, wherein the device includes a rectifier assembly comprising at least two stacks of at least two diodes, wherein the at least two stacks of diodes are arranged in parallel to each other. The device further comprises a capacitor assembly comprising at least two capacitors, wherein respective capacitor of the capacitor assembly is arranged in series between respective phase of the AC power supply and an associated stack of diodes in the rectifier assembly. This solution is however not adapted for use in a power supply of a marine vessel and the problems related to this.
In US 2014/197737 A1 is described a switching power source, a rectifier circuit, a pair of capacitive elements, and a load. The pair of capacitive elements are connected in series between the switching power source and an associated stack of the rectifier circuit and insulate the switching power source and the rectifier circuit. The switching power source may include a protection circuit that detects degradation of the pair of capacitive elements. By using a pair of capacitive elements a reduction in size and weight may be realized compared to the case of insulation using a transformer. This solution is however not adapted for use in a power supply of a marine vessel and the problems related to this.
There is accordingly a need for a device for providing galvanic isolation in an AC power supply to a marine vessel that replaces the need for heavy and large isolation transformers on either the power supply side or the marine vessel side.
There is further a need for a device for providing galvanic isolation in an AC power supply to a marine vessel that reduces the footprint of electrical equipment on a marine vessel.
There is further a need for a device for providing galvanic isolation in an AC power supply to a marine vessel that limits the volume of equipment required on the power supply side.
There is further a need for a device for providing galvanic isolation in an AC power supply to a marine vessel that in the event of a ground fault on board the marine vessel, the AC current will flow between the marine vessel and power supply grounds, thus enabling the power supply side electrical protection to react.
There is also a need for a device for providing galvanic isolation in an AC power supply to a marine vessel that removes the need for electrical protection equipment as is required on the marine vessel side of an isolation transformer.
There is also a need for a device for providing galvanic isolation in an AC power supply to a marine vessel that is implemented in an electrical charging architecture for an on board energy storage satisfying the above mentioned needs.
Object
The main object of the present invention is to provide a device for providing galvanic isolation in an AC power supply to a marine vessel that partly or entirely satisfies the above needs and improves upon the shortcomings found in the prior art.
It is further an object of the present invention to provide a device for providing galvanic isolation in an AC power supply to a marine vessel replacing the need for heavy and large isolation transformers on either the power supply side or the marine vessel side.
An object of the present invention is to provide a device for providing galvanic isolation in an AC power supply to a marine vessel reducing the footprint of electrical equipment on the marine vessel.
It is further an object of the present invention to provide a device for providing galvanic isolation in an AC power supply to a marine vessel limiting the volume of equipment required on the power supply side.
An object of the present invention is to provide a device for providing galvanic isolation in an AC power supply to a marine vessel such that in event of a ground fault on board the marine vessel, the AC current will flow between the marine vessel and power supply grounds, thus enabling the power supply side electrical protection to react.
It is further an object of the present invention to provide a device for providing galvanic isolation in an AC power supply to a marine vessel removing the need for electrical protection equipment as is required on the marine vessel side of an isolation transformer.
An object of the present invention is further to provide a device for providing galvanic isolation in an AC power supply to a marine vessel that is implemented within an electrical charging architecture for on board energy storage according to the above mentioned objects.
It is further an object of the present invention to provide a device for providing galvanic isolation in an AC power supply to a marine vessel providing a galvanically isolated AC/DC rectifier.
An object of the present invention is further to provide a device for providing galvanic isolation in an AC power supply to a marine vessel capable of rectification of the AC power supply and delivery of controlled DC current for charging of on board energy storage.
It is further an object of the present invention to provide a device for providing galvanic isolation in an AC power supply to a marine vessel providing self-regulated charging current limiting during charging of the energy storage.
An object of the present invention is further to provide a device for providing galvanic isolation in an AC power supply to a marine vessel providing over-voltage protection (protects against overcharging) during charging of the energy storage.
Further objects of the present invention will appear from the following description, claims and attached drawings.
The invention
A device for providing galvanic isolation in an AC (alternating current) power supply to a marine vessel according to the present invention is described in claim 1. Preferable features of the device for providing galvanic isolation in an AC power supply to a marine vessel are described in the remaining claims.
The device for providing galvanic isolation in an AC power supply to a marine vessel according to the present invention is formed by a rectifier assembly and a capacitator assembly. The device for providing galvanic isolation in an AC power supply to a marine vessel is connected to an AC power supply source at one side, such as an AC power supply grid (shore supply grid), and to a consumer network at the other side, such as a DC distribution system or the DC voltage bus of an AC converter supplying AC power to consumers on board the marine vessel.
The AC power supply can be a single-phase AC power supply source or a poly-phase AC supply source.
The rectifier assembly is according to the present invention formed by at least two stacks of at least two diodes arranged in series to form a diode bridge, wherein the stacks of diodes are arranged in parallel to each other. The number of stacks of diodes, according to the present invention, corresponds to the number of phases for poly-phase AC power supplies, and for singlephase AC power supplies the rectifier assembly comprises at least two stacks of diodes.
The capacitor assembly is according to the present invention formed by at least two capacitors or capacitor units, wherein the number of capacitors or capacitor units at least corresponds to the number of stacks of diodes of the rectifier assembly. Respective capacitor or capacitor unit of the capacitor assembly is, according to the present invention, arranged in series between respective phase of the AC power supply and a connection point between the at least two diodes in series of an associated stack of diodes. The capacitor assembly is according to the present invention arranged to stop DC currents from flowing in the AC power supply circuit, accordingly providing galvanic isolation between the AC power supply and the marine vessel.
According to a further embodiment of the device for providing galvanic isolation in an AC power supply to a marine vessel the device comprises an apparatus for monitoring health of the capacitors of the capacitor assembly.
According to a further embodiment of the present invention the device for providing galvanic isolation in an AC power supply to a marine vessel is provided with a plug or connector for easy connection to a corresponding plug or connector of the AC power supply.
Accordingly, the device for providing galvanic isolation in an AC power supply to a marine vessel can be considered to be a galvanically isolated AC/DC rectifier that rectifies the supplied AC power to produce DC distribution voltage or DC voltage on a bus of an AC converter supplying AC power to consumers on board the marine vessel.
It is a considerable advantage with the present invention that the capacitor assembly and rectifier assembly can be arranged/packaged together as one unit. By integrating the capacitor assembly and rectifier assembly as one unit the footprint of the electrical equipment on the marine vessel is reduced. Another advantage is that the volume of electric equipment required on the power supply side is limited.
The device for providing galvanic isolation in an AC power supply to a marine vessel according to the present invention further replaces the need for heavy and large isolation transformers on either the AC power supply side or the marine vessel side.
The device for providing galvanic isolation in an AC power supply to a marine vessel according to the present invention further ensures that, in the event of a ground fault on board the marine vessel, the AC current will flow between the marine vessel and AC power supply grounds, thus enabling the AC power supply side electrical protection to react. Accordingly, the present invention removes the need for electrical protection equipment as is required on the marine vessel side of an isolation transformer.
The present invention is especially suitable for implementation in an electrical charging architecture for on board energy storage.
The charging current for charging of the energy storage is determined by internal impedance of the energy storage and/or distribution system and the difference between energy storage voltage and voltage waveform that is presented at the rectifier assembly output.
According to one embodiment of the present invention, the capacitor assembly comprises capacitor units for each phase, wherein the capacitor units comprising at least two capacitors which can be switched between series configuration and parallel configuration. The inclusion of capacitors in series, i.e. series capacitor, in the AC supply line supplying the rectifier assembly alters the rectifier assembly output voltage by changing the effective input voltage presented to the rectifier assembly. The change in effective input voltage is due to the charging of the series capacitors (voltage drop) by the load current.
According to the present invention, the effective series capacitance may be changed through the switching of fixed series capacitances into a parallel configuration. Switching may be achieved with mechanical contactors, triac, SCR (Silicon controlled rectifier) or other electronic switching devices. Further, by using phase controlled gating of the switching devices enabled is zero voltage switching, which will result in stepwise increase/decrease of capacitance without switching transient.
According to a further embodiment of the present invention, the device for providing galvanic isolation in a power supply to a marine vessel further comprises variable inductance units, for each phase, arranged between the device and the AC power supply. The effective phase inductance can thus according to the present invention be changed by adjusting the air gap of the variable inductance units. The adjustment may e.g. be achieved with a servomechanism. Modification of the effective phase inductance in the AC supply line supplying the rectifier assembly also alters the rectifier assembly output voltage by changing the effective input voltage presented to the rectifier assembly bridge.
According to further embodiment of the device for providing galvanic isolation in a power supply to a marine vessel it further comprises a controllable transformer with variable voltage output, arranged between the device and the AC power supply. The controllable transformer with variable voltage output can according to the present invention be used to regulate the voltage of the AC power supply source. The regulation may be achieved with a servomechanism to select the appropriate tap on a winding with multiple taps (discrete regulation), or by adjusting the position of a sliding wiper (continuously variable regulation) of the controllable transformer.
In an alternative embodiment of the device for providing galvanic isolation in a power supply to a marine vessel, the voltage of the AC power supply source may be changed through AVR (Automatic Voltage Regulator) control if the device is serviced by a dedicated generator. Such an arrangement is common in marine vessels, locomotives and automobiles, where battery charging by an on board AC generator and prime mover is intended.
By adjusting the series capacitance, the AC power supply voltage or the inductance of the AC power supply, the rectifier assembly output voltage may be modified. In this manner the battery charging current may be regulated.
Controlled charging current may be achieved by feedback, wherein the actual charging current is measured and compared against a reference charging current.
The reference charging current is usually determined by a BMS (Battery Management System). The reference value is dependent on various factors such as battery SOC (State of charge), power availability at the AC power supply source, ambient temperature, time available for charging and so forth.
Further preferable features and advantageous details of the present invention will appear from the following example description, claims and attached drawings.
Example
The present invention will below be described in further detail with references to the attached drawings where:
Figure 1 is a principle drawing of a device for providing galvanic isolation in a power supply to a marine vessel according to a first embodiment the present invention,
Figure 2 is a principle drawing of a device for providing galvanic isolation in a power supply to a marine vessel according to a second embodiment of the present invention,
Figure 3 is a principle drawing of a device for providing galvanic isolation in a power supply to a marine vessel according to a further embodiment of the present invention,
Figure 4 is a principle drawing of a device for providing galvanic isolation in a power supply to a marine vessel according to a further embodiment of the present invention,
Figures 5 is principle drawings of details of the embodiment of Figure 4, and
Figures 6-7 are principle drawings of a device for providing galvanic isolation in a power supply to a marine vessel according to further embodiments of the present invention.
Reference is now made to Figure 1 which is a principle drawing of a device 10 for providing galvanic isolation in an AC power supply to a marine vessel according to a first embodiment of the present invention. In the embodiment shown in Figure 1 the device 10 for providing galvanic isolation in an AC power supply to marine vessel is adapted for a three phase AC power supply 50 on one side and to a consumer network 60 of a marine vessel on the other side. The consumer network 60 in the shown example is a DC-distribution system. The AC power supply 50 is e.g. an AC shore power grid. In the shown example the DC-distribution system 60 is arranged to an energy storage device 70 formed by batteries. Intelligent charging electronics, such as a BMS system, can of course, be arranged between the DC-distribution system 60 and the energy storage device 70. The device 10 for providing galvanic isolation according to the present invention is formed by a rectifier assembly 20 and a capacitor assembly 30. The rectifier assembly 20 is formed by at least two stacks 21a-c of at least two diodes 22 arranged in series forming a diode bridge, wherein the number of stacks 21a-c of diodes 22 (in series) corresponds to the number of phases of the AC power supply 50 for poly-phase AC power supplies 50, and the stacks 21a-c are arranged in parallel.
The capacitor assembly 30 is in the first embodiment formed by capacitors 31a-c, wherein the number of capacitors 31a-c corresponds to the number of stacks 21a-c of diodes 22 and accordingly the number of phases of the power supply 50. According to the first embodiment of present invention a respective capacitor 31a-c is arranged in series between respective phase of the AC power supply 50 and the two diodes 22 of an associated stack 21a-c in the rectifier assembly 20. By this a galvanically isolated AC/DC rectifier 20 is achieved. The capacitors 31a-c are arranged to stop DC currents from flowing in the AC power supply 50 circuit, thus providing galvanic isolation between the AC power supply 50 and the marine vessel.
Furthermore, according to the present invention these capacitors 31a-c can be packaged with the rectifier assembly 20 that rectifies the supplied AC power from the AC power supply 50 to produce the DC distribution voltage for the DC distribution system 60 on the marine vessel.
Reference is now made to Figure 2 showing a second embodiment of the present invention. According to the present invention the device 10 providing galvanic isolation in an AC power supply to the marine vessel further includes apparatus 100 for monitoring the health of the capacitors 31a-c. It is desired to monitor the capacitors 31a-c as a short circuited capacitor 31a-c would permit galvanic currents to flow. Further, an open circuited capacitor 31a-c would block the flow of current (charging current) to the rectifier assembly 20. A drop in capacitance or an increase in the capacitor’s 31a-c equivalent series resistance would further decrease the efficiency of the galvanically isolated AC/DC converter (rectifier assembly 20).
The number of capacitors 31a-c in the capacitor assembly 30 can for each phase of the AC power supply 50 comprise several capacitors 31a-c arranged in series and/or parallel, as e.g. shown in Figures 4 and 5. The capacitor assembly 30 can further be provided with several sub assemblies of capacitors 31a-c which are controllable by means of switches 33, as e.g. shown in Figure 5, which can switch between the sub assemblies for redundancy or for altering the properties of the capacitor assembly 30 if required or desired. The controlling can be based on the monitoring of the health of the capacitors 31a-c by the apparatus 100 or other measurements or information, as is further discussed below.
Reference is now made to Figure 3 showing a further embodiment of the present invention where the device 10 according to the present invention is provided with a plug or connector 80 for easy connection to a corresponding plug or connector 81 of the AC power supply 50. In the example is shown a three-phase plug or connector 80, 81.
Reference is now made to Figures 4 and 5 showing principle drawings of a further embodiment of the device 10 for providing galvanic isolation. In this embodiment the capacitor assembly 30 is formed by capacitor units 32a-c for each phase, wherein each capacitor unit 32a-c are formed by at least two capacitors 31a-c, respectively, arranged to be switched between a series configuration and parallel configuration, as shown in Figure 5, by means of mechanical contactors 33, triac, SCR (Silicon controlled rectifier) or other electronic switching devices. By this is enabled the possibility to alter the rectifier assembly 20 output voltage, which will be especially suitable when charging an energy storage 70 on board a vessel, as this enable regulating the battery charging current.
Reference is now made to Figures 6a-b showing principle drawings of a further embodiment of the device 10 for providing galvanic isolation in a power supply to a marine vessel. In this embodiment the device 10 further comprises variable inductor units 90a-c for each phase, arranged between the AC power supply source 50 and the capacitor assembly 30 of the device 10. The variable inductor units 90a-c can be arranged at the connection side of the device 10, as shown in Figure 6a, or at the connection side of the AC power supply source 50, as shown in Figure 6b. By this is enabled the possibility to alter the effective phase inductance, which will be especially suitable when charging an energy storage 70 on board a vessel, as the effective phase inductance also can be used to alter the rectifier assembly 20 output voltage by changing the effective input voltage presented to the rectifier assembly 20.
Reference is now made to Figure 7 showing a principle drawing of a further embodiment of the device 10 for providing galvanic isolation in a power supply to a marine vessel. In this embodiment the device 10 further comprises a controllable transformer 200 with variable voltage output, arranged between the AC power supply source 50 and the device 10. By this is enabled the possibility to alter the voltage of the AC power supply 50 when the AC power supply source is a dedicated generator, which will be especially suitable when charging an energy storage 70 on board a vessel.
In the shown embodiments, where the DC distribution system 60 is used for charging an energy storage 70, the use of capacitors 31a-c or capacitor units 32a-c to provide galvanic isolation to the rectifier assembly 20 (charging circuit) replaces the need for heavy and large isolation transformers on either the AC power supply 50 side (shore) or the marine vessel side (of the charging circuit).
By integrating the capacitors 31a-c or capacitor units 32a-c with the rectifier assembly 20 a reduction in the footprint of the electrical charging equipment is achieved on the maritime vessel, and the volume of equipment required on the AC power supply 50 side (shore-side) is limited.
If a ground fault arises on board the marine vessel, the AC current will flow between the marine vessel and AC power supply 50 grounds, thus enabling AC power supply 50 side (shore-side) electrical protection to react. This removes the need for electrical protection equipment as is required on the marine vessel side of an isolation transformer.
Even though the example shows an embodiment with a three phase AC power supply 50 as an example of a poly-phase AC power supply, the present invention is also applicable to provide galvanic isolation for a single-phase AC power supply. In connection with a single-phase AC power supply 50 it will be required that the rectifier assembly 20 comprises at least two stacks 21a-c of diodes 22 and that the capacitor assembly 30 comprises at least two capacitors 31a-c or capacitor units 32a-c arranged in series between the phases of the AC power supply 50 and the two diodes 22 of the associated stack 21a-c of diodes 22 in the rectifier assembly 20.
The features of the above described embodiments can be combined to form other embodiments within the scope of the attached claims.
The above described device 10 for providing galvanic isolation in an AC power supply can further be implemented as a part of an AC power supply 50 feeding an AC to AC converter.
Even though the examples makes use of an AC power supply 50 grid, the present invention is applicable for marine vessel-to-vessel power transfer.
Modifications
The present invention is applicable for applications where the direct current potential between two electrical systems/sub-systems needs to remain isolated.
Claims (12)
1. Device (10) for providing galvanic isolation in a power supply to a marine vessel, wherein the device (10) is connected to an AC power supply (50) at one side and to a consumer network (60) at the other side, wherein the device (10) includes a rectifier assembly (20) comprising at least two stacks (21a-c) of at least two diodes (22), wherein the at least two stacks (21a-c) of diodes (22) are arranged in parallel to each other, wherein the device (10) further comprises a capacitor assembly (30) comprising at least two capacitors (31a-c) or capacitor units (32a-c), wherein respective capacitor (31a-c) or capacitor unit (32a-c) of the capacitor assembly (30) is arranged in series between respective phase of the AC power supply (50) and an associated stack (21a-c) of diodes (22) in the rectifier assembly (20), characterized in that the device (10) is arranged such that, in event of ground fault on board the marine vessel, AC current will flow between the marine vessel and AC power supply (50) grounds, enabling the AC power supply (50) side electrical protection to react.
2. Device (10) according to claim 1, characterized in that the number of stacks (21a-b) of diodes (22) corresponds to the number of phases for poly-phase AC power supplies (50).
3. Device (10) according to claims 1-2, characterized in that the number of capacitors (31a-c) or capacitor units (32a-c) in the capacitor assembly (30) at least corresponds to the number of stacks (21a-c) of diodes (22).
4. Device (10) according to claims 1-3, characterized in that at least one capacitor (31a-c) or capacitor unit (32a-c) is arranged in series between each phase of the AC power supply (50) and each associated stack (21a-c) of diodes (22), connected between the at least two diodes (22) of each stack (21a-b).
5. Device (10) according to claims 1-4, characterized in that the capacitor assembly (30) and rectifier assembly (20) are integrated as one unit.
6. Device (10) according to claim 1, characterized in that the capacitor assembly (30) is arranged for stopping DC current from flowing in the AC power supply (50).
7. Device (10) according to claim 1, characterized in that the capacitor unit (32a-c) comprises at least two capacitors (31a-c) which can switched between series configuration and parallel configuration.
8. Device (10) according to claim 1, characterized in that there are arranged variable inductance units (90a-c) for each phase between the device (10) and the AC power supply (50).
9. Device (10) according to claim 1, characterized in that there is arranged a controllable transformer (200) with variable voltage output between the device (10) and the AC power supply (50).
10. Device (10) according to claim 1, characterized in that the AC power supply (50) is provided from a generator.
11. Device (10) according to any one of the preceding claims, characterized in that the device (10) comprises an apparatus (100) for monitoring health of the capacitors (31a-c) of the capacitor assembly (30).
12. Device (10) according to any one of the preceding claims, characterized in that the device (10) is implemented in an electrical charging architecture for on board energy storage (70).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NO20171852A NO20171852A1 (en) | 2017-11-21 | 2017-11-21 | Device for providing galvanic isolation in an AC power supply to a marine vessel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NO20171852A NO20171852A1 (en) | 2017-11-21 | 2017-11-21 | Device for providing galvanic isolation in an AC power supply to a marine vessel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| NO343384B1 true NO343384B1 (en) | 2019-02-18 |
| NO20171852A1 NO20171852A1 (en) | 2019-02-18 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| NO20171852A NO20171852A1 (en) | 2017-11-21 | 2017-11-21 | Device for providing galvanic isolation in an AC power supply to a marine vessel |
Country Status (1)
| Country | Link |
|---|---|
| NO (1) | NO20171852A1 (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6151519U (en) * | 1984-09-03 | 1986-04-07 | ||
| US6265879B1 (en) * | 1999-07-14 | 2001-07-24 | Keith W. Landreth | Electrical integrity test system for boats |
| US20090302687A1 (en) * | 2005-01-27 | 2009-12-10 | Siemens Aktiengesellschaft | Medium Voltage Land Connection for Marine Vessels |
| RU108243U1 (en) * | 2011-06-07 | 2011-09-10 | Сергей Иванович Титков | PULSE VOLTAGE CONVERTER OUTPUT CIRCUIT, PULSE VOLTAGE CONVERTER AND PULSE VOLTAGE POWER SUPPLY (OPTIONS) |
| EP2528233A1 (en) * | 2011-05-24 | 2012-11-28 | Siemens Aktiengesellschaft | Coupling circuit for coupling a control circuit to a semiconductor switch |
| US20140197737A1 (en) * | 2011-09-22 | 2014-07-17 | Toshiba Lighting & Technology Corporation | Electrical Equipment |
-
2017
- 2017-11-21 NO NO20171852A patent/NO20171852A1/en unknown
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6151519U (en) * | 1984-09-03 | 1986-04-07 | ||
| US6265879B1 (en) * | 1999-07-14 | 2001-07-24 | Keith W. Landreth | Electrical integrity test system for boats |
| US20090302687A1 (en) * | 2005-01-27 | 2009-12-10 | Siemens Aktiengesellschaft | Medium Voltage Land Connection for Marine Vessels |
| EP2528233A1 (en) * | 2011-05-24 | 2012-11-28 | Siemens Aktiengesellschaft | Coupling circuit for coupling a control circuit to a semiconductor switch |
| RU108243U1 (en) * | 2011-06-07 | 2011-09-10 | Сергей Иванович Титков | PULSE VOLTAGE CONVERTER OUTPUT CIRCUIT, PULSE VOLTAGE CONVERTER AND PULSE VOLTAGE POWER SUPPLY (OPTIONS) |
| US20140197737A1 (en) * | 2011-09-22 | 2014-07-17 | Toshiba Lighting & Technology Corporation | Electrical Equipment |
Also Published As
| Publication number | Publication date |
|---|---|
| NO20171852A1 (en) | 2019-02-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| TCEN | Translation of claims (non-ep application) | ||
| CHAD | Change of the owner's name or address (par. 44 patent law, par. patentforskriften) |
Owner name: KONGSBERG MARITIME CM AS, NO |
|
| CHAD | Change of the owner's name or address (par. 44 patent law, par. patentforskriften) |
Owner name: KONGSBERG MARITIME AS, NO |