Voltage conversion system and mobility machine

Abstract

The invention relates to a voltage conversion system comprising an interconnection device (103) comprising a first output terminal (BS1) and a second output terminal (BS2), a first DC-DC voltage converter (101) and a second DC-DC voltage converter (102), each of the DC-DC voltage converters having an output terminal (S1, S1'), the second control device (μ2) furthermore comprising a fault detection module (DP102) for detecting a fault with the second DC-DC voltage converter (102), the interconnection device (103) comprising: a switch (T1), a switch (T3), a switch (T2), and / or a switch (T4), two switches (T5, T6). The switches (T5, T6) are controlled so as to close when a closing condition is met, said closing condition comprising the fault detection module (DP102) of the second control device detecting a fault with the second DC-DC voltage converter.

Description

Description TITLE: VOLTAGE CONVERSION SYSTEM AND MOBILITY MACHINE Technical field of the invention

[0001] The present invention relates to a voltage conversion system and a power supply device comprising such a voltage conversion system. The present invention also relates to a mobility device comprising such a voltage conversion system or such a power supply device.

[0002] A mobility device is, for example, a motorized land vehicle, a train, an aircraft, or a drone. A motorized land vehicle is, for example, a motor vehicle, a motorcycle, a motorized bicycle, or a motorized wheelchair. Technological background

[0003] A voltage conversion system is known from the state of the art, comprising a first and a second DC-DC voltage converter, each comprising a first and a second input terminal, a first output terminal and a second output terminal, and each converting a high voltage greater than 100V present between the two input terminals into a low voltage less than 100V present between the two output terminals. In this voltage conversion system, the first output terminal of the first voltage converter is different from the first output terminal of the second voltage converter, while the second output terminal of each of the two DC-DC voltage converters is connected to the same electrical ground.

[0004] This voltage conversion system according to the state of the art further comprises a first control device controlling the first DC-DC voltage converter and a second control device controlling the second DC-DC voltage converter.

[0005] In such a voltage conversion system, each of the first output terminals independently supplies electrical power to a separate electrical network.

[0006] So, when one of the DC-DC voltage converters is not working, the electrical network connected to the output of this voltage converter continuous-continuous is no longer electrically powered and the devices connected to this electrical network stop working.

[0007] It may thus be desirable to provide a voltage conversion system which makes it possible to overcome at least part of the aforementioned problem. Summary of the invention

[0008] It is therefore proposed, according to a first aspect of the invention, a voltage conversion system comprising: a first and a second DC-DC voltage converter each comprising a first and a second input terminal, a first and a second output terminal and each converting a high voltage greater than 100V present between the two input terminals into a low voltage less than 100V present between the two output terminals, the second output terminal of each of the two DC-DC voltage converters being connected to the same electrical ground; a first control device and a second control device, the first control device controlling the first DC-DC voltage converter, the second control device controlling the second DC-DC voltage converter, a first module for detecting a failure of the second DC-DC voltage converter;and an interconnection device comprising:; • a first output terminal, • a second output terminal, • several switches each produced by the parallel association of a transistor and a diode, said diode being able to be an intrinsic diode of said transistor, these switches including: o a switch T1 arranged between the first output terminal of the first DC-DC voltage converter and the first output terminal of the interconnection device so that the cathode of the diode of the switch T 1 is electrically connected to a first midpoint between the switch T1 and the first output terminal, o a switch T3 arranged between the first output terminal of the second DC-DC voltage converter and the second output terminal so that the cathode of the diode of the switch T3 is electrically connected to a second midpoint between the switch T3 and the second output terminal, o a switch T2 arranged between the first midpoint and the first output terminal so that the cathode of the diode of the switch T2 is electrically connected to the first midpoint, and / or a switch T4 arranged between the second midpoint and the second output terminal so that the cathode of the diode of the switch T4 is electrically connected to the second midpoint, o two switches T5, T6 arranged in series between the first and second midpoints so that the anodes of the diodes of these two switches T5, T6 are electrically connected respectively to the first and second midpoints or so that the cathodes of the diodes of these two switches T5, T6 are electrically connected respectively to the first and second midpoints.

[0009] This voltage conversion system is characterized in that the transistor of the switch T5 and the transistor of the switch T6 are controlled to close when a closing condition is achieved, said closing condition comprising the detection of a failure of the second direct-direct voltage converter by the first detection module.

[0010] In other words, the transistors of switches T5, T6 are closed when the closing condition is met.

[0011] By definition, a DC-DC voltage converter is faulty when it does not convert its input voltage to its output voltage in accordance with the control process implemented by its control device.

[0012] Thus, thanks to the invention, it is possible, upon detection that the second direct-direct voltage converter is faulty, to continue to supply the electrical network connected to the output of this second direct-direct voltage converter by the first direct-direct voltage converter.

[0013] It will be appreciated that when the switch T2 is present, the first switch T1 and the second switch T2 are arranged in series in that order between the first output terminal of the first DC-DC voltage converter and the first output terminal of the interconnection device so that the cathodes of the diodes of these two switches T1, T2 are electrically connected to each other at the first midpoint. Similarly, when switch T4 is present, switch T3 and switch T4 are arranged in series in this order between the first output terminal of the second DC-DC voltage converter and the second output terminal so that the cathodes of the diodes of these two switches T3, T4 are electrically connected to each other at the second midpoint.

[0014] The term "in series" means that the two components are connected one after the other on the same branch of the electrical circuit, but not that they necessarily carry the same current. Indeed, the term "in series" also covers the case where there is another branch of the electrical circuit connected between the two components.

[0015] The voltage conversion system may further comprise one or more of the following optional features, in any combination that is technically possible.

[0016] According to a first characteristic, the second control device comprises the first detection module.

[0017] According to another characteristic, the first detection module comprises a module for detecting an overvoltage between the two output terminals of the second DC-DC voltage converter, said first detection module detecting a fault when the overvoltage detection module detects an overvoltage, i.e. detects that the voltage between the two output terminals of the second DC-DC voltage converter is greater than a first predetermined voltage threshold.

[0018] According to another characteristic, the first detection module comprises a module for detecting an undervoltage between the two output terminals of the second DC-DC voltage converter, said first detection module detecting a fault when the undervoltage detection module detects an undervoltage, i.e. detects that the voltage between the two output terminals of the second DC-DC voltage converter is lower than a second predetermined voltage threshold, the second predetermined voltage threshold being lower than the first predetermined voltage threshold.

[0019] According to another characteristic, the first detection module comprises a module for detecting an overcurrent at the first output terminal of the second DC-DC voltage converter, said first detection module detecting a fault when the overcurrent detection module detects an overcurrent, i.e. the current at the first output terminal of the second DC-DC voltage converter is greater than a predetermined current threshold.

[0020] According to another characteristic, the first detection module comprises a module for monitoring an internal signal, for example a voltage or a current, of the second DC-DC voltage converter, said first detection module detecting a fault when the supervision module detects that the internal signal is greater than a first predetermined threshold or that the internal signal is less than a second predetermined threshold.

[0021] According to another characteristic, the voltage conversion system comprises a second module for detecting a failure of the second DC-DC voltage converter and the closing condition further comprises the detection of a failure of the second DC-DC voltage converter by the second detection module.

[0022] According to another characteristic, the first control device comprises the second detection module.

[0023] According to another characteristic, the second detection module comprises a module for detecting an overvoltage between the two output terminals of the second DC-DC voltage converter, said second detection module detecting a fault when the overvoltage detection module detects an overvoltage, i.e. detects that the voltage between the two output terminals of the second DC-DC voltage converter is greater than a third predetermined voltage threshold.

[0024] According to another characteristic, the second detection module comprises a module for detecting an undervoltage between the two output terminals of the second DC-DC voltage converter, said second detection module detecting a fault when the undervoltage detection module detects an undervoltage, i.e. detects that the voltage between the two output terminals of the second DC-DC voltage converter is less than a fourth predetermined voltage threshold, the fourth predetermined voltage threshold being lower than the third predetermined voltage threshold.

[0025] According to another characteristic, the second detection module comprises a module for detecting an overcurrent at the first output terminal of the second DC-DC voltage converter, said second detection module detecting a fault when the overcurrent detection module detects an overcurrent, i.e. the current at the first output terminal of the second DC-DC voltage converter is greater than a predetermined current threshold.

[0026] According to another characteristic, the second detection module comprises a module for monitoring an internal signal, for example a voltage or a current, of the second DC-DC voltage converter, said second detection module detecting a fault when the supervision module detects that the internal signal is greater than a first predetermined threshold or that the internal signal is less than a second predetermined threshold.

[0027] According to yet another characteristic, the second DC-DC voltage converter comprises at least one transistor driven by a gate driver, said gate driver being powered by a power supply and the detection of a failure of the second DC-DC voltage converter by the second detection module comprises the detection that said gate driver is not powered by said power supply.

[0028] According to another characteristic, the voltage conversion system comprises a third module for detecting a failure of the second DC-DC voltage converter and the closing condition further comprises the detection of a failure of the second DC-DC voltage converter by at least two of the first, second and third detection modules.

[0029] According to another characteristic, the third detection module comprises a module for detecting an overvoltage between the two output terminals of the second DC-DC voltage converter, said third detection module detecting a fault when the overvoltage detection module detects an overvoltage, i.e. detects that the voltage between the two output terminals of the second DC-DC voltage converter is greater than a fifth predetermined voltage threshold.

[0030] According to another characteristic, the third detection module comprises a module for detecting an undervoltage between the two output terminals of the second DC-DC voltage converter, said third detection module detecting a fault when the undervoltage detection module detects an undervoltage, i.e. detects that the voltage between the two output terminals of the second DC-DC voltage converter is lower than a sixth predetermined voltage threshold, the sixth predetermined voltage threshold being lower than the fifth predetermined voltage threshold.

[0031] According to another characteristic, the third detection module comprises a module for detecting an overcurrent at the first output terminal of the second DC-DC voltage converter, said third detection module detecting a fault when the overcurrent detection module detects an overcurrent, i.e. the current at the first output terminal of the second DC-DC voltage converter is greater than a predetermined current threshold.

[0032] According to another characteristic, the third detection module comprises a module for monitoring an internal signal, for example a voltage or a current, of the second DC-DC voltage converter, said third detection module detecting a fault when the supervision module detects that the internal signal is greater than a first predetermined threshold or that the internal signal is less than a second predetermined threshold.

[0033] According to yet another characteristic, the second DC-DC voltage converter comprises at least one transistor driven by a gate driver, said gate driver being powered by a power supply and the detection of a failure of the second DC-DC voltage converter by the third detection module comprises the detection that said gate driver is not powered by said power supply.

[0034] According to yet another characteristic, the first and second control devices are capable of communicating with a control unit via a communication bus, said control unit being capable of sending a message to stop the second DC-DC voltage converter to said second control device via said communication bus and the detection of a failure of the second DC-DC voltage converter by the second detection module comprises the detection of the absence of sending of said stop message on said communication bus to the second control device.

[0035] By definition, the second DC-DC voltage converter is stopped when it is not converting the high voltage present between its two input terminals into a low voltage present between its two output terminals.

[0036] According to yet another characteristic, the first and / or the second control device comprise means for comparing the measurement of a voltage at the second output terminal of the interconnection device with a non-zero threshold, said closing condition further comprising the detection by said comparison means of the first and / or the second control device that the voltage at the second output terminal of the interconnection device is greater than said threshold.

[0037] According to yet another characteristic, the threshold is positive.

[0038] According to yet another characteristic, the transistor of the switch T5 and the transistor of the switch T6 are controlled in linear mode for a predetermined time prior to the detection by the comparison means of the first and / or second control device that the voltage at the second output terminal of the interconnection device is greater than said threshold.

[0039] According to yet another feature, the second control device is designed to control the closed, open or semi-open state (also called "linear" state) of the transistor of the switch T3 and of the transistor of the switch T4 when the latter is present.

[0040] According to yet another feature, said closing condition further comprises the closing of the transistor of switch T4 when the latter is present, and the opening of the transistor of switch T3 by the second control device. Indeed, following a failure of the second DC-DC voltage converter, it is possible for switches T3 and T4 to be automatically opened, by the second control device. Thus, to close switches T5 and T6, it is necessary to first close switch T4 and leave switch T3 open, as specified in this feature.

[0041] According to yet another feature, the first control device is designed to control the closed, open or semi-open state (also called "linear" state) of the transistor of the switch T 1.

[0042] According to yet another feature, said closing condition further comprises the closing of the transistor of the switch T 1 by the first control device. Indeed, upon failure of the second DC-DC voltage converter, the switch T 1 is normally left closed by the first control device. Nevertheless, it is preferable to ensure this before closing the switches T5 and T6, as indicated in this feature.

[0043] According to yet another feature, the transistor of switch T5 and the transistor of switch T6 are connected in series through an inductor.

[0044] According to a second aspect of the invention, there is also provided a power supply device comprising a voltage conversion system according to the first aspect of the invention and further comprising a first battery capable of delivering a first high voltage, said first battery being connected between the first input terminal and the second input terminal of the first DC-DC voltage converter.

[0045] The power supply device may further comprise one or more of the following optional features, in all combinations that are technically possible.

[0046] According to a first characteristic, the first battery is also connected between the first input terminal and the second input terminal of the second DC-DC voltage converter or further comprising a second battery capable of delivering a second high voltage, said second battery being connected between the first input terminal and the second input terminal of the second DC-DC voltage converter.

[0047] According to another characteristic, the power supply device further comprises a control unit and a communication bus and the first control module, the second control module and said control unit are able to communicate with each other via said communication bus, said control unit being able to send a message to stop the second DC-DC voltage converter on said communication bus to the second control module.

[0048] According to another characteristic, said control unit is also capable of sending the message to stop the second direct-direct voltage converter on said communication bus to the first control module.

[0049] According to a third aspect of the invention, there is also provided an electrical system comprising a voltage conversion system according to the invention or an electrical power supply device according to the invention, as well as a first low voltage network connected to the first output terminal and a second low voltage network connected to the second output terminal.

[0050] According to one feature, switch T4 is present, preferably with switch T2 absent, and the second low voltage network comprises a low voltage battery.

[0051] According to another feature, switch T2 is present, preferably with switch T4 absent, and the first low voltage network comprises a low voltage battery.

[0052] According to a fourth aspect of the invention, there is also provided a mobility device comprising a voltage conversion system according to the first aspect of the invention or an electrical power supply device according to the second aspect of the invention. Brief description of the figures

[0053] The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which: [Fig. 1] is a very simplified view of a mobility device in which the invention can be implemented, [Fig. 2] is an electronic diagram representing an electrical power supply device in a first embodiment of the invention, [Fig. 3] is an electronic diagram representing a DC-DC voltage converter with an isolated double bridge, [Fig. 4] is an electronic diagram representing an electrical power supply device in a second embodiment of the invention, [Fig. 5] is an electronic diagram representing a power supply device in a third embodiment of the invention, and [Fig. 6] is an electronic diagram representing a power supply device in a fourth embodiment of the invention, [Fig. 7] is an electronic diagram representing an interconnection device according to an alternative embodiment, and [Fig. 8] is an electronic diagram representing an interconnection device according to another alternative embodiment. Detailed description of the invention

[0054] With reference to [Fig. 1], a mobility device 10, in which the invention in a first embodiment is used, will now be described.

[0055] The mobility device 10 is, in the example described, a motor vehicle. This mobility device 10 comprises a battery BAT designed, for example, to electrically power an electric motor propelling the mobility device 10.

[0056] The battery BAT is designed to provide a DC voltage referenced to a first ground GND1 and called battery voltage VBAT. This battery voltage is in the example described here a high voltage, that is to say a voltage greater than 100 V, preferably greater than 150 V. Thus, conversely, a low voltage is a voltage lower than 100 V.

[0057] In the example described here, the BAT battery is designed to provide a voltage of 800V. The BAT battery itself consists of a first battery BAT 1 in series with a second battery BAT2. Each of the batteries BAT 1 and BAT2 is designed to provide a respective voltage VBAT 1 , VBAT2 of 400V.

[0058] In the example described here, batteries BAT1 and BAT2 comprise the same number N of cells or accumulators in series. For example, the cells of batteries BAT 1 and BAT2 are lithium-ion cells or lithium-iron-phosphate cells known as LFP cells or lithium nickel-manganese-cobalt cells known as NMC cells.

[0059] Alternatively, batteries BAT1 and BAT2 may comprise a different number of cells or accumulators in series.

[0060] The mobility device 10 further comprises a first low-voltage network 104 designed to be powered by a direct voltage, called the first network voltage V4 and referenced to a second ground GND2.

[0061] The mobility device 10 further comprises a second low-voltage network 105 designed to be powered by a direct voltage, called second network voltage V5 and referenced to the second ground GND2.

[0062] In the example described here, the first and second network voltages are equal.

[0063] To obtain the first network voltage V4 and the second network voltage V5 from the voltage VBAT 1 of the first battery BAT 1 and / or the voltage VBAT2 of the second battery BAT2, the mobility device 10 comprises a voltage conversion system SC.

[0064] The voltage conversion system SC comprises: a first DC-DC voltage converter 101, a second DC-DC voltage converter 102, and an interconnection device 103

[0065] The first DC-DC voltage converter 101 is designed to convert the voltage VBAT1 into a first intermediate voltage VB1 referenced to the second ground GND2, the voltage VBAT1 of the first battery BAT1 and the first intermediate voltage VB1 thus respectively forming an input voltage present between a first input terminal E1 and a second input terminal E2 of the first DC-DC voltage converter 101 and an output voltage of the first DC-DC voltage converter 101 present between a first output terminal S1 and a second output terminal S2 of the first DC-DC voltage converter 101.

[0066] The second DC-DC voltage converter 102 is designed to convert the voltage VBAT2 into a second intermediate voltage VB2 referenced to the second ground GND2, the voltage VBAT2 of the second battery BAT2 and the second intermediate voltage VB2 thus respectively forming an input voltage present between a first input terminal ET and a second input terminal E2' of the second DC-DC voltage converter 102 and an output voltage present between a first output terminal ST and a second output terminal S2' of the second DC-DC voltage converter 102.

[0067] In the example described here, the two batteries BAT 1 and BAT2 being in series, the first input terminal E1 of the first DC-DC voltage converter 101 and the second input terminal E2' of the second DC-DC voltage converter are electrically connected.

[0068] In the embodiment described herein, the first and second DC-DC voltage converters have the same topology. In an alternative embodiment, the first DC-DC voltage converter 101 and the second DC-DC voltage converter 102 could have different topologies.

[0069] Furthermore, the second output terminal S2, S2' of each of the two DC-DC voltage converters 101, 102 is connected to the second electrical ground GND2.

[0070] It will be noted that the assembly formed by the voltage conversion system SC and the two batteries BAT 1 and BAT2 is an electrical power supply device AE according to the invention.

[0071] [Fig.2] shows the first embodiment of an AE power supply comprising the SC voltage conversion system.

[0072] In this embodiment, the interconnection device 103 comprises a first input terminal BE1 electrically connected to the first output terminal S1 of the first DC-DC voltage converter 101 and intended to receive the first intermediate voltage VB1, a second input terminal BE2 electrically connected to the second output terminal ST of the second DC-DC voltage converter 102 and intended to receive the second intermediate voltage VB2, a first output terminal BS1 intended to provide the first network voltage V4 and a second output terminal BS2 intended to provide the second network voltage V5.

[0073] In the example described here, the first low voltage network 104 comprises at least one capacitor C and loads Z1 while the second low voltage network 105 comprises a low voltage battery 203 having between its terminals a nominal voltage identical to the second network voltage V5 and loads Z2.

[0074] The interconnection device 103 further comprises an inductance L, a first switch Int1, a second switch Int2, a third switch I nt3, a fourth switch I nt4, a fifth switch I nt5 and a sixth switch I nt6, each of said switches I nt1 to I nt6 being produced by the parallel association of a transistor T1 to T6 and a diode, said diode being able to be an intrinsic diode of the transistor. Thus, in the on state, respectively blocked, the transistor T1-T6 behaves like a closed, respectively open switch I nt1 -I nt6. The term "open" will subsequently be used to indicate that the transistor is blocked and the term "closed" to indicate that the transistor is on.

[0075] Transistors T1 to T6 can be FET (Field-Effect Transistor) or insulated gate bipolar transistors, generally designated by the acronym IGBT (Insulated Gate Bipolar Transistor) or high electron mobility transistors designated by the acronym HEMT (High-Electron-Mobility Transistor). For example, FET transistors can be silicon MOSFETs (Si-MOSFET) or silicon carbide MOSFETs (SiC-MOSFET) or are gallium nitride FETs (GaN-FET). For example, HEMT transistors can be gallium nitride HEMTs (GaN-HEMT).

[0076] In the example described here, transistors T1 to T6 are silicon MOSFETs and the corresponding diode of switches Int1 to Int6 is the intrinsic diode of transistor T1 to T6.

[0077] The first transistor T1 and the second transistor T2 are arranged in series in this order between the first input terminal BE1 and the first output terminal BS1 so that the cathodes of the intrinsic diodes of these two transistors T1, T2 are electrically connected to each other at a first midpoint PM1,

[0078] The third transistor T3 and the fourth transistor T4 are arranged in series in this order between the second input terminal BE2 and the second output terminal BS2 so that the cathodes of the intrinsic diodes of these two transistors T3, T4 are electrically connected to each other at a second midpoint PM2, and

[0079] The fifth switch T5 and the sixth transistor T6 are arranged in series in this order between the second midpoint PM2 and the first midpoint PM1 so that the anodes of the intrinsic diodes of these two transistors T5, T6 are electrically connected to each other via the inductance L.

[0080] The particular connection of the intrinsic diodes of the first and second transistors T1, T2 makes it possible to prevent a flow of current between the first input terminal BE1 and the first output terminal BS1 of the interconnection device 103.

[0081] Similarly, the particular connection of the intrinsic diodes of the third and fourth transistors T3, T4 makes it possible to prevent a flow of current between the second input terminal BE2 and the second output terminal BS2 of the interconnection device 103.

[0082] Similarly, the particular connection of the intrinsic diodes of the fifth and sixth transistors T5, T6 makes it possible to prevent current flow between the first midpoint PM1 and the second midpoint PM2.

[0083] In this embodiment, the first DC-DC voltage converter 101 is controlled by a first control device p1 by means of commands C1. In other words, the control of the first DC-DC voltage converter 101 is carried out by a control method known to those skilled in the art and implemented by the first control device p1. In other words, the first control device comprises a digital processing unit, for example a microprocessor or a microcontroller, capable of generating the commands C1 for controlling the first DC-DC voltage converter.

[0084] Likewise, the second DC-DC voltage converter 102 is controlled by a second control device p2 by means of commands C2. In other words, the control of the second DC-DC voltage converter 102 is carried out by a control method known to those skilled in the art and implemented by the second control device p2. In other words, the second control device comprises a digital processing unit, for example a microprocessor or a microcontroller, capable of generating the commands C2 for controlling the second DC-DC voltage converter.

[0085] In the embodiment described herein, the first DC-DC voltage converter 101 and the second DC-DC voltage converter 102 are controlled so that the first intermediate voltage VB1 and the second intermediate voltage VB2 are equal.

[0086] The first DC-DC voltage converter 101 also controls the on, off or linear state of the transistors T1 and T2 by means of CT control.

[0087] The second control device p2 also controls the on, off or linear state of transistors T3 and T4 by means of commands C2' and the on, off or linear state of transistors T5 and T6.

[0088] The second control device p2 also comprises a DP102 module for detecting a failure of the second DC-DC voltage converter 102 and a module EV25 for comparing the voltage V5 with a threshold, for example equal to 90% of the nominal value of the voltage of the low voltage battery 203.

[0089] With reference to [Fig. 3], an example of a first DC-DC voltage converter 101 will now be described. As previously indicated, in the example described here, the second DC-DC voltage converter 102 has a topology identical to that of the first voltage converter 101.

[0090] More specifically, the DC-DC voltage converter 101 is in this example a dual isolated bridge DC / DC converter, also called in English “Dual Active Bridge”.

[0091] This isolated double bridge DC / DC converter comprises in the example presented a transformer T comprising a primary winding P and a secondary winding S, a first DC / AC conversion stage EC1 connected to the primary winding P of the transformer T, a second AC / DC conversion stage EC2, mounted symmetrically with respect to the first conversion stage EC1 and connected to the secondary winding S of the transformer T. This voltage converter also comprises an output capacitor CS connected between the first output terminal S1 and the second electrical ground GND2 as well as an inductive circuit, here an inductance L1, connected between the second conversion stage EC2 and the terminal of the output capacitor CS which is not connected to the second electrical ground GND2, i.e. to the terminal of the output capacitor CS connected to the first output terminal S1.

[0092] In the example described here, the first conversion stage EC1 comprises an H-bridge formed of two switching arms, each of the two switching arms consisting of two transistors connected to a midpoint and connected in series between the first input terminal E1 and the second input terminal E2. In the example described here, the transistors G1A, G1B, G2A, G2B are MOSFETs. The first switching arm is formed of the MOSFETs G1A, G1B and has its midpoint connected to a first end of the primary P of the transformer T while the second switching arm is formed of the MOSFETs G2A, G2B and has its midpoint connected to a second end, different from the first end, of the primary P of the transformer T.

[0093] Similarly, in the example described here, the second conversion stage EC2 comprises an H-bridge also formed of two switching arms, each of the two switching arms consisting of two transistors connected to a midpoint and connected in series between the first output terminal S1 and the second electrical ground GND2. In the example described here, the transistors G3A, G3B, G4A, G4B are MOSFETs. The first switching arm is formed of the MOSFETs G3A, G3B and has its midpoint connected to a first end of the secondary S of the transformer T while the second switching arm is formed of the MOSFETs G4A, G4B and has its midpoint connected to a second end, different from the first end, of the secondary S of the transformer T.

[0094] The transistors G1A, G1B, G2A, G2B, G3A, G3B, G4A, G4B are each controlled to open and close by a control device, produced in the example described by a gate driver, upon receipt of the commands C1 issued by the first control device p1 of the first DC-DC voltage converter 101. Furthermore, each of the gate drivers is electrically powered by a power supply. For reasons of readability, only the gate driver PG1A and the power supply A1A of the transistor G1A are shown in [Fig. 3],

[0095] In connection with [Fig.2], we will now describe the operation of the interconnection device 103 when the voltage conversion system SC changes from a first operating mode to a second operating mode.

[0096] Initially, the transistors T1 to T6 are controlled to the open state by their respective control device, the first DC-DC voltage converter 101 and the second DC-DC voltage converter 102 are switched off, i.e. the first, respectively the second, DC-DC voltage converter does not convert the voltage VBAT1, respectively VBAT2 into a first, respectively second, intermediate voltage.

[0097] To enter the first operating mode of the voltage conversion system SC, the first control device p1 closes the transistors T1 and T2, and controls the first DC-DC voltage converter 101 so that it converts the voltage VBAT 1 into a first intermediate voltage VB1 while the second control device p1 closes the transistors T3 and T4 and controls the second DC-DC voltage converter 102 so that it converts the voltage VBAT2 into a second intermediate voltage VB2. The transistors T1 and T2, respectively T3 and T4 being closed, and the transistors T5 and T6 being open, the first intermediate voltage VB1, respectively the second intermediate voltage VB2 is equal to the first network voltage V4, respectively the second network voltage V5. Thus, in this first operating mode, the two low-voltage networks 104, 105 are electrically powered separately.

[0098] Following detection of a failure of the second DC-DC voltage converter 102 by the failure detection module DP102 of the second control device p2, the voltage conversion system SC will switch to a second operating mode.

[0099] To detect the failure of the DC-DC voltage converter 102, the failure detection module DP 102 comprises one or more of the following modules: a module for detecting an overvoltage of the second intermediate voltage VB2, a module for detecting an undervoltage of the second intermediate voltage VB2, a module for detecting an overcurrent at the first output terminal ST or a module for monitoring a signal, for example a current or a voltage, internal to the second DC-DC voltage converter 102. Thus, a failure of the DC-DC voltage converter is detected when the second intermediate voltage is too small or too high or when too high a current appears at the first output terminal ST or when a signal internal to the second DC-DC voltage converter has an abnormal value.

[0100] To switch to the second operating mode, the second control device p2 opens, by a command C2', the transistor T3 and the transistor T4 and stops, by a command C2, the second DC-DC voltage converter 102. When stopping the second DC-DC voltage converter, the second control device p2 also cuts off the power supply gate drivers of the transistors of this second direct-direct voltage converter 102.

[0101] Then, upon detection by the comparison module EV25 of the second control device p2 that the voltage V5 measured between the second output terminal BS2 and the second ground GND2 is greater than a non-zero threshold, for example equal to 90% of the nominal value of the battery 203, the second control device p2 sends a closing command C2' to close the transistor T4 while keeping the transistor T3 open. The comparison of the voltage V5 and the nominal voltage of the battery 203 makes it possible to verify that there is no short circuit, in particular with the second ground GND2, within the second low-voltage network 105.

[0102] The second control device p2 also sends a command C2” to close the transistors T5 and T6. The closing of the transistors T5 and T6 allows the electrical supply of the second low voltage network 105 by the first DC-DC voltage converter 101 so that the two low voltage networks are electrically supplied by the same DC-DC voltage converter 101.

[0103] In other words, the voltage conversion system SC switches to a second operating mode when a closing condition is met, said closing condition comprising the detection of a failure of the second DC-DC voltage converter 102 by the failure detection module DP102 of the second control device p2 and the detection by the comparison means EV25 of the second control device p2 that the voltage at the second output terminal BS2 of the interconnection device 103 is greater than a threshold.

[0104] Alternatively, the closing condition may only include the detection of a failure of the second DC-DC voltage converter 102 by the failure detection module DP102 of the second control device p2. In this case, the second control device p2 opens, by a command C2', the transistor T3 and keeps the transistor T4 closed then stops, by a command C2, the second DC-DC voltage converter 102 before issuing the command C2” to close the transistors T5 and T6.

[0105] Thus in the second mode of operation, the voltage conversion system SC ensures the continuity of the power supply to the second network low voltage 105 when the second DC-DC voltage converter 102 is faulty.

[0106] With reference to [Fig. 4], a second embodiment of the invention will now be presented. Elements identical to, or analogous to, those of the first embodiment bear the same numerical reference in the description of the second embodiment.

[0107] In this second embodiment of the invention, the first control device p1 further comprises a module for detecting a fault DF102 of the direct-direct voltage converter 102.

[0108] In this second embodiment of the invention, the second control device p2, respectively the first control device p1, is capable of transmitting a control command C2”, respectively C1”, of the on, off or linear state of the transistors T5 and T6 to a control device 300 of the transistors T5, T6. The control device 300 controls the closing of the transistors T5 and T6 when it simultaneously receives a closing command C2” of the transistors T5 and T6 transmitted by the second control device p2 and a closing command C1” of the transistors T5 and T6 transmitted by the first control device p1.

[0109] We will now describe the operation of the interconnection device 103, in this second embodiment of the invention, when the voltage conversion system SC switches from the first operating mode to its second operating mode.

[0110] Initially, the voltage conversion system SC is in the first operating mode. As a reminder, in this first operating mode of the voltage conversion system SC, the transistors T5 and T6 are open. In addition, the transistors T1 and T2 are closed and the first DC-DC voltage converter 101 converts the voltage VBAT1 into a first intermediate voltage VB1 (equal to the voltage V4) which supplies the first low voltage network 104 while the transistors T3 and T4 are closed and the second DC-DC voltage converter 102 converts the voltage VBAT2 into a second intermediate voltage VB2 (equal to the voltage V5) which supplies the second low voltage network 105. Thus, in this first operating mode, the two low voltage networks are electrically supplied separately.

[0111] As in the first embodiment of the invention, the voltage conversion system SC switches to its second mode of operation when a closing condition is achieved.

[0112] In the second embodiment of the invention, this closing condition comprises not only the detection of a failure of the second DC-DC voltage converter 102 by the failure detection module DP102 of the second control device p2 but also the detection of a failure of the second DC-DC voltage converter 102 by the failure detection module DF102 of the second DC-DC voltage converter 102 of the first control device p1.

[0113] We will now describe the sequence of events that causes the SC voltage conversion system to transition from its first mode of operation to its second mode of operation.

[0114] Following the detection of a failure of the second DC-DC voltage converter 102 by the failure detection module DP102 of the second control device p2, the second control device p2 opens, by a command C2', the transistor T3 and the transistor T4 and stops, by a command C2, the second DC-DC voltage converter 102. In addition, the second control device p2 cuts off the power supply to the gate drivers of the transistors of this DC-DC voltage converter 102.

[0115] Then, upon detection by the comparison module EV25 of the second control device p2 that the voltage V5 measured between the second output terminal BS2 and the second ground GND2 is greater than a non-zero threshold, for example equal to 90% of the nominal value of the voltage of the battery 203, the second control device p2 sends a closing command C2' to close the transistor T4 while keeping the transistor T3 open. Comparing the voltage V5 with the nominal voltage of the battery 203 makes it possible to verify that there is no short circuit, in particular with the second ground GND2, within the second low-voltage network 105.

[0116] The second control device p2 also sends a command C2” to close the transistors T5 and T6 to the control device 300.

[0117] Furthermore, the DF102 module for detecting a failure of the second direct-direct voltage converter 102 of the first control device p1 detects that the second DC-DC voltage converter 102 is stopped. This detection is carried out, for example, by detecting that at least one of the power supplies of the gate drivers of the transistors of the second DC-DC voltage converter 102 is stopped, i.e. no longer supplies its gate driver. This detection can be carried out by monitoring the output of one or more diodes, the anodes of these diodes each being connected to a different power supply of a gate driver.

[0118] Alternatively, the module DF102 for detecting a failure of the second DC-DC voltage converter 102 of the first control device p1 can detect a failure of the DC-DC voltage converter 102 when the second intermediate voltage VB2 is too small or too high or when too high a current appears at the first output terminal S1' or when an internal signal of the second DC-DC voltage converter 102 has an abnormal value.

[0119] Following this detection of a failure of the second DC-DC voltage converter 102, the first control device p1 sends a command C1” to close the transistors T5 and T6 to the control device 300.

[0120] Upon joint reception of the command C1” issued by the first control device p1 and the command C2” issued by the second control device p2, the control device 300 closes the transistors T5 and T6.

[0121] The closing of the transistors T5 and T6 allows the electrical supply of the second low voltage network 105 by the first DC-DC voltage converter 101 so that the two low voltage networks are electrically supplied by the same DC-DC voltage converter 101.

[0122] In an alternative embodiment of this second operating mode, the first control device p1 also comprises an evaluation module EV15 of the voltage V5 and the closing condition also comprises the detection by the comparison means EV15 of the first control device p1 that the voltage at the second output terminal BS2 of the interconnection device 103 is greater than a threshold S' which is for example equal to the threshold S. Thus, the first control device p1 sends, in this case, the command C1” to close the transistors T5 and T6 to the control device 300 only if the voltage at the second output terminal BS2 of the interconnection device 103 is greater at threshold S' and if the second direct-direct voltage converter 102 is faulty.

[0123] With reference to [Fig. 5], a third embodiment of the invention will now be presented. Elements identical to, or analogous to, those of the first or second embodiment bear the same numerical reference in the description of the third embodiment.

[0124] Compared to the second embodiment of the invention, the two control devices p1 and p2 communicate with a control unit ECU via a NET communication bus. The NET communication bus is, for example, a CAN data bus (Controller Area Network). The control unit ECU is, for example, a control unit of the mobility device 10.

[0125] We will now describe the operation of the interconnection device 103, in this third embodiment of the invention, when the voltage conversion system SC switches from its first operating mode to its second operating mode.

[0126] Initially, the transistors T1 to T6 are controlled to the open state by their respective control device, the first DC-DC voltage converter 101 and the second DC-DC voltage converter 102 are stopped.

[0127] The ECU control unit of the mobility device 10 initiates the transition to the first operating mode of the voltage conversion system SC by transmitting via the communication bus NET an activation message of the first DC-DC voltage converter 101 and the second DC-DC voltage converter 102.

[0128] Upon receipt of this activation message, the first control device p1 closes the transistors T1 and T2, and starts the first DC-DC voltage converter 101 so that it converts the voltage VBAT 1 into a first intermediate voltage VB1 which supplies the first low voltage network 104 while the second control device closes the transistors T3 and T4 and starts the second DC-DC voltage converter 102 so that it converts the voltage VBAT2 into a second intermediate voltage VB2 which supplies the second low voltage network 105.

[0129] The voltage conversion system is thus in its first operating mode and in this first operating mode, the two low voltage networks 104, 105 are electrically powered separately since the transistors T5 and T6 are open.

[0130] As in the second embodiment of the invention, the voltage conversion system SC enters its second mode of operation when a closing condition is achieved.

[0131] Compared to the second embodiment of the invention, the transition from the first operating mode to the second operating mode of the voltage conversion system SC differs only with respect to the operation of the module DF102 for detecting a failure of the second DC-DC voltage converter 102 of the first control device p1.

[0132] The DF102 module detects a failure of the second DC-DC voltage converter 102 only when the second DC-DC voltage converter 102 is stopped and when simultaneously the ECU control unit has not sent a stop message of the second DC-DC voltage converter 102 on the NET communication bus.

[0133] With reference to [Fig. 6], a fourth embodiment of the invention will now be presented. Elements identical to, or analogous to, those of the previous embodiments bear the same numerical reference in the description of the fourth embodiment.

[0134] This fourth embodiment of the invention is distinguished from the previous embodiments by the nature of the first low voltage network 104 and the second low voltage network 105. In this fourth embodiment, the first low voltage network 104 comprises a low voltage battery 204 and loads Z1 while the second low voltage network 105 comprises at least one capacitor C and loads Z2. In other words, in this embodiment the second low voltage network 105 does not comprise a battery.

[0135] We will now describe the operation of the interconnection device 103, in this fourth embodiment of the invention, when the voltage conversion system SC switches from its first operating mode to its second operating mode.

[0136] As in the other embodiments of the invention, in the first operating mode of the voltage conversion system SC, the transistors T5 and T6 are open. Furthermore, the transistors T1 and T2 are closed and the first DC-DC voltage converter 101 converts the voltage VBAT1 into a first intermediate voltage VB1 which supplies the first low voltage network 104 while the transistors T3 and T4 are closed and the second DC-DC voltage converter 102 converts the voltage VBAT2 into a second intermediate voltage VB2 which supplies the second low voltage network 105. Thus, in this first operating mode, the two low voltage networks are electrically supplied separately.

[0137] As in previous embodiments of the invention, the voltage conversion system SC enters a second operating mode when a closing condition is achieved.

[0138] In the fourth embodiment of the invention, this closing condition comprises not only the detection of a failure of the second DC-DC voltage converter 102 by the failure detection module DP102 of the second DC-DC voltage converter 102 of the second control device p2 but also the detection of a failure of the second DC-DC voltage converter 102 by the failure detection module DF 102 of the second DC-DC voltage converter 102 of the first control device p1.

[0139] Following the detection of a failure of the second DC-DC voltage converter 102 by its failure detection module DP102, the second control device p2 opens, by a command C2', the transistor T3 while keeping the transistor T4 closed and stops, by a command C2, the second DC-DC voltage converter 102. In addition, the second control device p2 cuts off the power supply to the gate drivers of the transistors of this DC-DC voltage converter 102.

[0140] The second control device p2 also sends a command C2” to put the transistors T5 and T6 into linear mode to the control device 300.

[0141] Likewise, following this detection of a failure of the second DC-DC voltage converter 102 by its failure detection module DF102, the first control device p1 sends a command C1” to put the transistors T5 and T6 into linear operation to the control device 300.

[0142] Upon joint reception of the command C1” emitted by the first control device p1 and the command C2” emitted by the second control device p2, the control device 300 puts the transistors T5 and T6 into linear mode, which makes it possible to progressively supply the second low-voltage network 105 by the first direct-direct voltage converter 101.

[0143] Then, upon detection after a predetermined time, by the comparison module EV25 of the second control device p2 that the voltage V5 measured between the second output terminal BS2 and the second ground GND2 is greater than a non-zero threshold S, for example equal to 90% of the nominal operating value of the second low-voltage network 105, the second control device p2 sends a command C2” to close the transistors T5 and T6 to the control device 300. Upon receipt of this command C2”, the control device 300 closes the transistors T5 and T6.

[0144] Conversely, if the comparison module EV25 of the second control device p2 detects that the voltage V5 measured between the second output terminal BS2 and the second ground GND2 is lower than the threshold S, the second control device p2 sends a command C2” to open the transistors T5 and T6 to the control device 300.

[0145] On receipt of this command C2” to open the transistors T5 and T6, the control device 300 opens the transistors T5 and T6 so that the second low voltage network 105 is no longer powered by the first DC-DC voltage converter 101.

[0146] In an alternative embodiment, upon detection at the end of the predetermined time, by the comparison module EV15 of the first control device p1 that the voltage V5 measured between the second output terminal BS2 and the second ground GND2 is greater than the threshold S, the first control device p1 also sends a command C1” to close the transistors T5 and T6 to the control device 300. Upon simultaneous reception of the commands C1” and C2” to close the transistors T5 and T6, the control device 300 closes the transistors T5 and T6.

[0147] Conversely, if the comparison module EV15 of the first control device p1 detects that the voltage V5 measured between the second output terminal BS2 and the second ground GND2 is lower than the threshold S, the first control device p1 sends a command C1” to open the transistors T5 and T6 to the control device 300. On simultaneous receipt of commands C1” and C2” to open transistors T5 and T6, control device 300 opens transistors T5 and T6.

[0148] In conclusion, it will be noted that the invention is not limited to the embodiments described above. It will indeed appear to those skilled in the art that various modifications can be made to the embodiments described above, in light of the teaching which has just been disclosed to them.

[0149] For example, in the embodiments presented previously, the battery BAT comprises two batteries BAT 1 and BAT2 in series. Alternatively, the battery BAT may be formed of only one battery BAT 1 providing a single high voltage to the input terminals of the first and second DC-DC voltage converter. In this case, the first input terminal E1 is electrically and directly connected to the first input terminal ET and the second input terminal E2 is electrically and directly connected to the second input terminal E2'.

[0150] For example, the fifth switch T5 and the sixth transistor T6 can be arranged in series in this order between the second midpoint PM2 and the first midpoint PM1 so that the cathodes of the intrinsic diodes of these two transistors T5, T6 are electrically connected to each other via the inductance L.

[0151] Referring to Figure 7, switch T2 may be omitted, but keeping switch T4, particularly when the second low voltage network 105 to which switch T4 is connected, includes low voltage battery 203.

[0152] Referring to Figure 8, switch T4 may be omitted, but keeping switch T2, particularly when the first low voltage network 104 to which switch T2 is connected, comprises low voltage battery 204.

[0153] In the variants of Figures 7 and 8, the examples of control of the interconnection device described previously with reference to Figures 1 to 6 can be used.

[0154] In the detailed presentation of the invention given above, the terms used should not be interpreted as limiting the invention to the embodiments set forth in this description, but should be interpreted to include all equivalents the prediction of which is within the reach of those skilled in the art. by applying his general knowledge to the implementation of the teaching which has just been disclosed to him.

Claims

Claims [1] Voltage conversion system (SC) comprising: a first (101) and a second (102) DC-DC voltage converter each comprising a first (E1, ET) and a second input terminal (E2, E2'), a first (S1, ST) and a second output terminal (S2, S2') and each converting a high voltage (VBAT1, VBAT2) greater than 100V present between the two input terminals into a low voltage (VB1, VB2) less than 100V present between the two output terminals, the second output terminal of each of the two DC-DC voltage converters being connected to the same electrical ground (GND2); a first control device (p1) and a second control device (p2), the first control device (p1) controlling the first DC-DC voltage converter (101), the second control device (p2) controlling the second DC-DC voltage converter (102);a first detection module (DP102) of a failure of the second direct-direct voltage converter (102); and an interconnection device (103) comprising:; • a first output terminal (BS1), • a second output terminal (BS2), • several switches each produced by the parallel association of a transistor and a diode, said diode being able to be an intrinsic diode of said transistor, these switches including: o a switch T 1 arranged between the first output terminal (S1) of the first DC-DC voltage converter (101) and the first output terminal (BS1) of the interconnection device (103) so that the cathode of the diode of the switch T 1 is electrically connected to a first midpoint (PM1) between the switch T1 and the first output terminal (BS1), o a switch T3 arranged between the first output terminal (ST) of the second DC-DC voltage converter (102) and the second output terminal (BS2) so that the cathode of the diode of the switch T3 is electrically connected to a second midpoint (PM2) between the switch T3 and the second output terminal (BS2), o a switch T2 arranged between the first midpoint (PM1) and the first output terminal (BS1) so that the cathode of the diode of the switch T2 is electrically connected to the first midpoint (PM1), and / or a switch T4 arranged between the second midpoint (PM2) and the second output terminal (BS2) so that the cathode of the diode of the switch T4 is electrically connected to the second midpoint (PM1), o two switches T5, T6 arranged in series between the first (PM1) and the second midpoint (PM2) so that the anodes of the diodes of these two switches T5, T6 are electrically connected respectively to the first (PM1) and to the second midpoint (PM2) or so that the cathodes of the diodes of these two switches T5,T6 are electrically connected respectively to the first (PM1) and to the second midpoint (PM2); said voltage conversion system (SC) being characterized in that the transistor of the switch T5 and the transistor of the switch T6 are controlled to close when a closing condition is achieved, said closing condition comprising the detection of a failure of the second DC-DC voltage converter (102) by the first detection module (DP102)., [2] Voltage conversion system (SC) according to the preceding claim, further comprising a second detection module (DF102) for detecting a failure of the second DC-DC voltage converter (102) and in which the closing condition further comprises the detection of a failure of the second DC-DC voltage converter (102) by the second detection module (DF102). [3] Voltage conversion system (SC) according to the preceding claim, wherein the second DC-DC voltage converter (102) comprises at least one transistor (G1A) driven by a gate driver (PG1A), said gate driver (PG1A) being powered by a power supply (A1A) and wherein the detection of a failure of the second DC-DC voltage converter (102) by the second detection module (DF102) of a failure of the second DC-DC voltage converter (102) comprises detecting that said gate driver (PG1A) is not powered by said power supply (A1A). [4] Voltage conversion system (SC) according to claim 2 or 3, wherein the first (p1) and the second (p2) control devices are capable of communicating with a control unit (ECU) via a communication bus (CAN), said control unit (ECU) being capable of sending a stop message of the second DC-DC voltage converter (102) to said second control device (p2) via said communication bus (CAN) and wherein the detection of a failure of the second DC-DC voltage converter (102) by the second detection module (DF102) comprises the detection of the absence of sending of said stop message on said communication bus (CAN) to the second control device (p2). [5] Voltage conversion system according to any one of claims 1 to 4, wherein the first (p1) and / or the second (p2) control device comprise means (EV25, EV15) for comparing the measurement of a voltage at the second output terminal (BS2) of the interconnection device with a non-zero threshold (S), said closing condition further comprising the detection by said comparison means of the first and / or the second control device that the voltage at the second output terminal (BS2) of the interconnection device is greater than said threshold (S). [6] Voltage conversion system according to the preceding claim, in which the transistor of the switch T5 and the transistor of the switch T6 are controlled in linear mode for a predetermined time prior to the detection by the comparison means of the first and / or second control device that the voltage at the second output terminal (BS2) of the interconnection device is greater than said threshold (S). [7] Voltage conversion system according to any one of claims 1 to 6, wherein said closing condition further comprises closing the transistor of the switch T4 when the latter is present, and opening the transistor of the switch T3 by the second control device (p2). [8] A voltage conversion system according to any one of claims 1 to 7, wherein said closing condition further comprises closing the transistor of the switch T 1 by the first control device (p1). [9] Electrical power supply device (AE) comprising a voltage conversion system (SC) according to any one of the preceding claims and further comprising a first battery (BAT1) capable of delivering a first high voltage (VBAT1), said first battery (BAT1) being connected between the first input terminal (E1) and the second input terminal (E2) of the first DC-DC voltage converter (101). [10] Electrical power supply device (AE) according to the preceding claim wherein the first battery (BAT1) is also connected between the first input terminal (ET) and the second input terminal (E2') of the second DC-DC voltage converter (102) or further comprising a second battery (BAT2) capable of delivering a second high voltage (VBAT2), said second battery (BAT2) being connected between the first input terminal (ET) and the second input terminal (E2') of the second DC-DC voltage converter (102). [11] Power supply device (AE) according to the preceding claim further comprising a control unit (ECU) and a communication bus (CAN) and in which the first control module (p1), the second control module (p2) and said control unit (ECU) are able to communicate with each other via said communication bus (CAN), said control unit (ECU) being able to send a message to stop the second DC-DC voltage converter on said communication bus (CAN) to the second control module. [12] Electrical system comprising a voltage conversion system (SC) according to any one of claims 1 to 8 or an electrical power supply device according to any one of claims 9 to 11, as well as a first low voltage network (104) connected to the first output terminal (BS1) and a second low voltage network (105) connected to the second output terminal (BS2). [13] Electrical system according to claim 12, wherein the switch T4 is present, preferably with the switch T2 absent, and wherein the second low voltage network (105) comprises a low voltage battery (203). [14] An electrical system according to claim 12, wherein switch T2 is present, preferably with switch T4 absent, and wherein the first low voltage network (104) comprises a low voltage battery (204). [15] Mobility device (100) comprising a voltage conversion system (SC) according to any one of claims 1 to 8 or an electrical power supply device according to any one of claims 9 to 11 or an electrical system according to any one of claims 12 to 14.

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