ELECTRICAL INSULATION TESTING SYSTEM IN A MOTOR VEHICLE EQUIPPED WITH A HIGH VOLTAGE BATTERY

Description

ELECTRICAL INSULATION TESTING SYSTEM IN A MOTOR VEHICLE EQUIPPED WITH A HIGH VOLTAGE BATTERY ELECTRICAL INSULATION VERIFICATION SYSTEM IN A MOTOR VEHICLE EQUIPPED WITH A HIGH VOLTAGE BATTERY TECHNICAL SECTOR This solution concerns an electrical insulation testing system in a motor vehicle equipped with a high voltage battery, which allows for improved safety performance. EARLY ART As is known, electric or hybrid motor vehicles are equipped with: an electric or hybrid powertrain, which is capable of rotating at least one wheel resting on the ground; a rechargeable high-voltage battery pack (or more simply battery), which is capable of storing a specific amount of electrical energy to be supplied to the electric or hybrid powertrain; and an electronically controlled inverter, which is placed between the battery pack and the powertrain and is capable of transforming, based on commands given by the vehicle driver, the direct current electrical energy coming from the battery pack into alternating current electrical energy for the powertrain. As is known, the high-voltage battery is equipped internally with a management module, the so-called BMS module, a control unit that communicates with the electronics of the - 1 vehicle and is designed to manage the operation and monitor the operating status of the battery, for example, to prevent it from operating outside of safe conditions. Specifically, the BMS module is designed to control and manage all the electrochemical cells that make up the battery by monitoring their state of charge, temperature, voltage, and / or other parameters, for example, to implement state-of-charge balancing in the event of an imbalance between the various electrochemical cells. Since modern automotive batteries can reach nominal voltages of up to 800 V (generally operating at very high voltages, between 400 and 800 V), it is essential to be able to detect any ground faults that may compromise electrical insulation. Such failures may, for example, be due to the ageing of the electrical components, to stress of various kinds (mechanical, electrical, thermal or generally environmental) or to accidents to which the high voltage battery may be subjected, such as a puncture of a relative hermetic container in which the electrolytic cells are housed. When a ground fault occurs, there is a consequent significant reduction in electrical resistance - 2 associated with insulation, which involves the flow of a certain leakage current, of non-negligible value. Such faults can therefore be dangerous for people and / or for low voltage circuits of the same vehicle that share the same earth connection and can also cause the start of a fire inside the vehicle which can obviously have very serious consequences. It is therefore usually expected that high voltage batteries are equipped internally with a ground fault detection circuit (so-called GFD, Ground Fault Detection), capable of evaluating (possibly through appropriate estimates) the electrical resistance between the positive pole or terminal of the battery and the ground and / or between the negative pole or terminal of the same battery and the ground, under particular operating conditions specified by the current regulations. This ground fault detection circuit is typically included in the BMS module of the high voltage battery. In this case, this BMS module also has the function of monitoring the aforementioned insulation resistance, for example being configured to interrupt, by means of appropriate circuit breaking elements, the power supply to the loads by the battery itself in the event that it detects a variation in the - 3 insulation resistance potentially indicative of an earth fault. The present Applicant has found that, despite the important function it performs, the aforementioned ground fault detection circuit inside the BMS module, at least in certain situations, may not guarantee complete electrical safety with regard to the electrical isolation of the high voltage components inside the vehicle, which include not only the aforementioned high voltage battery, but also inverters, DC / DC voltage converters, or in general other loads operating at high voltage or in any case relating to the same high voltage bus present in the vehicle. In particular, the need to comprehensively monitor the vehicle's electrical insulation from high voltage is particularly acute in the case of prototype vehicles, given that their prototype nature generally makes the occurrence of faults or critical situations from a safety perspective more likely. PURPOSE OF THE INVENTION The aim of this solution is to provide an electrical insulation testing system, which can provide a response to the aforementioned need and generally guarantee an increase in the electrical safety of the vehicle against insulation losses. - 4 compared to high voltage. In accordance with the above-mentioned objective, according to the present solution a system as defined in the appended claims is provided. BRIEF DESCRIPTION OF THE FIGURES The present invention will now be described with reference to the attached drawings, which illustrate a non-limiting example of its implementation, in which: Figure 1 schematically shows a motor vehicle equipped with at least one electrical insulation testing system, in accordance with the present solution; - Figure 2 shows a schematic block diagram of the electrical insulation testing system; and - Figures 3-4 show state diagrams relating to operations performed by the electrical insulation testing system. DETAILED DESCRIPTION OF THE FORMS OF IMPLEMENTATION As will be described in detail below, one aspect of the present solution involves the implementation of an electrical insulation testing system in a motor vehicle which comprises: two separate and independently operating electrical insulation monitoring devices, a first device inside the high voltage battery and a second device outside the same high voltage battery; and also a control unit - 5 configured to implement appropriate cooperation (without mutual interference) between the two electrical insulation monitoring devices for verifying electrical insulation with respect to high voltage. This system thus allows for continuous verification and monitoring of the electrical insulation in the vehicle with respect to high voltage, in particular both when the contacts (or terminals) of the high voltage battery are closed, i.e. connected to a high voltage bus of the vehicle, and when the same contacts are open, i.e. not connected to the high voltage bus. Furthermore, the electrical insulation testing system advantageously includes appropriate user interface elements designed to continuously report over time, particularly visually, the status of the electrical insulation to a vehicle user, so as to clearly and promptly report any electrical insulation leaks or problems. With reference first to Figure 1, the number 1 indicates as a whole a motor vehicle, with electric or hybrid propulsion, having a body 2 supported on the ground by wheels 3 and comprising: an electric or hybrid propulsion unit 4, including at least one electric motor of the synchronous or asynchronous type, capable of rotating - 6 at least one of said wheels 3 and whose operation is controlled by a control unit (ECU - Electronic Control Unit) 100, also capable of supervising the general operation of the motor vehicle 1 itself (in a manner known per se, not described in detail here); and a high voltage battery (HVB, High Voltage Battery) 5, of the rechargeable type, which is able to accumulate within it a certain quantity of electrical energy to be supplied to the aforementioned powertrain 4. The powertrain 4 and the high voltage battery 5 are housed inside the body 2, with the electric or hybrid powertrain 4 being located at the rear and the high voltage battery 5 at the front of the same body 2 in the illustrated example. In a known manner and not illustrated here, an electric unit, in particular including an electronically controlled inverter, is interposed between the high voltage battery 5 and the powertrain 4 to transform, according to the commands given by the driver of the vehicle, the direct current electrical energy coming from the high voltage battery 5 into alternating current electrical energy for the powertrain 4. The high voltage battery 5 has, for example, a nominal capacity greater than or equal to 50 kWh and a nominal voltage between 400 V and 800 Volts, in particular equal to - 7 to 800 V. As shown schematically in the aforementioned Figure 1, the high voltage battery 5 internally comprises a group of electrolytic cells 8 and a BMS module 9, operationally coupled to the group of electrolytic cells 8, for the management and supervision of its operation. According to one aspect of the present solution, the motor vehicle 1 further comprises an insulation testing system 10, shown schematically in Figure 1, operatively coupled to the high voltage battery 5 and configured to continuously test the electrical insulation of a related high voltage line or bus with respect to ground (note that, despite the schematic view, part of such insulation testing system 10 may be included in the high voltage battery 5 itself). In greater detail, and as shown schematically in Figure 2, the high voltage battery 5 is coupled to a high voltage bus 12, to which are also coupled within the motor vehicle 1 (not illustrated here) a plurality of high voltage loads, generally indicated with 14, for example inverters, DC / DC converters or the like. In particular, the high voltage battery 5 is selectively coupled to the high voltage bus 12 via connection terminals 15 (shown in - 8 schematic); the aforementioned BMS module 9 is configured to control the opening or closing of such connection terminals 15 to determine the disconnection, respectively the connection, of the high voltage battery 5 to the high voltage bus 12. The motor vehicle 1 also comprises, in a known manner, a low voltage service battery 16, for example having a nominal voltage of 12V, the positive and negative poles of which are coupled to a low voltage line 17 to which a plurality of electrical services are associated inside the motor vehicle 1 (in a known manner, not illustrated in detail here). The service battery 16 is also coupled to the high voltage battery 5 and the high voltage loads 14. The aforementioned Figure 2 also shows the CAN (Controller Area Network) bus or line of the motor vehicle 1, indicated by 18, to which are coupled, among other things, the aforementioned BMS module 9 of the high voltage battery 5 and the aforementioned high voltage loads 14. The insulation testing system 10 comprises a first insulation monitoring device 20, arranged inside the high voltage battery 5, connected to the high voltage bus 12 and managed and controlled by the related BMS module 9. - 9 This first insulation monitoring device 20, of hardware type, can be, in a manner known per se not described in detail here, based on an electrical impedance measurement, being connected between the high voltage bus 12 and ground and being configured so as to superimpose a measurement voltage and consequently evaluate the insulation resistance. According to one aspect of the present solution, the insulation testing system 10 comprises a second insulation monitoring device 21, arranged outside the high voltage battery 5, in a related box or container 22, preferably in a position not accessible to the user of the motor vehicle 1, and connected to the high voltage bus 12. This second insulation monitoring device 21 is also of the hardware type and can be based for example on an electrical impedance measurement, being connected between the high voltage bus 12 and the ground, to evaluate the insulation resistance associated with the same high voltage bus 12. The second monitoring device 21 is further coupled to the service battery 16, as shown in the aforementioned Figure 2. The insulation testing system 10 further comprises an insulation control unit 24, arranged in a position - 10 distinct from and external to the aforementioned high voltage battery and to the aforementioned container 22 of the second insulation monitoring device 21 and operationally coupled to the same second insulation monitoring device 21 to monitor its operation and generally manage the operation of the insulation verification system 10. This isolation control unit 24 is also coupled to the service battery 16, as shown in the aforementioned Figure 2, from which it receives electrical power. In particular, the insulation control unit 24 comprises a microprocessor, microcontroller or similar digital processing unit, configured to execute an appropriate control logic of the aforementioned insulation verification system 10. This control logic is implemented by appropriate software (firmware) executed by the insulation control unit 24 and stored, in the form of programming code, in a non-volatile memory (not shown here) associated with the insulation control unit 24 itself; in particular, the insulation control unit 24, when executing this software, is configured to implement the aforementioned control logic. The insulation control unit 24 of the insulation verification system 10, although shown here - 11 schematically distinct from the control unit 100 of the motor vehicle 1, could coincide, or be part of the same control unit. The insulation testing system 10 also comprises one or more user interface elements 26, suitably arranged inside and / or outside the motor vehicle 1 and controllable by the aforementioned insulation control unit 24 to continuously provide a user of the same motor vehicle 1 with an indication of the insulation status with respect to the high voltage. In particular, these user interface elements 26 are configured to provide a visual indication and to this end comprise one or more LEDs (Light Emitting Diodes) or similar lighting components, having one or more different colors. In general, the insulation verification system 10 comprises at least one of these user interface elements 26; Figure 2 illustrates three of them by way of example, a first of which can be placed externally to the body 2 of the motor vehicle 1, for example on the roof; a second inside the passenger compartment, for example in correspondence with the windscreen; and a third also inside the passenger compartment, for example in correspondence with the dashboard. In particular, such user interface elements 26 are configured to provide at least: a first indication, - 12 for example illuminated by a first color, for example green, in the event that the insulation verification system 10 does not determine the presence of an insulation failure; and a second indication, for example illuminated by a second color, for example red, in the event that the insulation verification system 10 determines the presence of an insulation failure. As will be described below, one or more of the user interface elements 26 may include at least one additional LED or similar lighting component, to indicate for example the correct connection of the service battery 16 and the high voltage battery 5. In particular, the aforementioned insulation control unit 24 is configured to manage the second insulation monitoring device 21 to implement the insulation verification with respect to the high voltage, when the connection terminals 15 of the high voltage battery 5 are open and the same high voltage battery 5 is therefore decoupled from the high voltage bus 12. Furthermore, when the connection terminals 15 of the high voltage battery 5 are instead closed and the same high voltage battery 5 is thus coupled to the high voltage bus 12 and supplies the high voltage to the same high voltage bus 12, the insulation control unit 24 is - 13 configured to act as a simple interface between the first insulation monitoring device 20 and the user interface elements 26, in particular managing the operation of such user interface elements 26. In this condition, in fact, the insulation verification is delegated to the first insulation monitoring device 20, appropriately managed by the BMS module 9 of the high voltage battery 5. In particular, the insulation control unit 24 is configured to query the CAN bus 18 of the motor vehicle 1 to determine whether the high voltage battery 5 has the aforementioned connection terminals 15 open or closed and also to receive insulation status information from the BMS module 9. It is highlighted that this architecture of the insulation verification system 10 and this operation by the insulation control unit 24 allows for the implementation of continuous monitoring of the electrical insulation with respect to high voltage (in particular, between the high voltage bus 12 and the earth), through interference-free cooperation between the first and second insulation monitoring devices 20, 21. In one possible implementation, the operation of the isolation control unit 24 involves the implementation of a state machine, in which the - 14 transition between states is determined by events significant for electrical insulation monitoring. The main states that can be assumed by the insulation control unit 24 are for example the following: - 'NO FAULT - HV OFF': the high voltage bus 12 is not energized (the connection terminals 15 of the high voltage battery 5 are open) and the second insulation monitoring device 21 managed by the insulation control unit 24 has verified that the insulation resistance is above a pre-set insulation threshold Th, indicative of a safe condition (or absence of faults); the insulation control unit 24 itself therefore signals via the user interface elements 26 that the high voltage system is safe; - 'FAULT ISO - HV OFF': the high voltage bus 12 is not energized and the second insulation monitoring device 21 has verified that the insulation resistance is below the preset insulation threshold Th; the insulation monitoring unit 24 therefore signals via the user interface elements 26 that the high voltage system is unsafe; 'NO FAULT - HV ON' : the high voltage bus 12 is energised (the connection terminals 15 of the high voltage battery 5 are closed), therefore the insulation control unit 24 acts as an interface, interfacing with the - 15 first insulation monitoring device 20 (which in this case is responsible for monitoring the electrical insulation), and signals via the user interface elements 26 that the high voltage system is safe (the energized bus has no insulation losses); 'FAULT ISO - HV ON': The high voltage bus 12 is energized and the insulation monitoring unit 24 signals via the user interface elements 26 that the high voltage system is unsafe (the energized bus has suffered an insulation loss), having received corresponding status information from the first insulation monitoring device 20. In general, in the event of an insulation failure, determined by the first insulation monitoring device 20 (internal to the high voltage battery 5) or by the second insulation monitoring device 21 (external to the high voltage battery 5), the insulation control unit 24 signals the danger via the user interface elements 26 (e.g. by activating a fixed red signal). In one possible implementation, further states that can be assumed by the isolation control unit 24 may be the following: - 'NO TESTING': The insulation control unit 24 is substantially not powered, therefore it is not able to - 16 carry out or manage insulation measurements (12V power supply is not available as service battery 16 is disconnected); 'TESTING': the insulation monitoring unit 24 is powered and checks whether the connection terminals 15 of the high voltage battery 5 are open or closed, if open, it starts monitoring the insulation on the high voltage bus 12 via the second insulation monitoring device 21; - 'ISO FAULT': this state essentially indicates that at least one of the first and second insulation monitoring devices 20, 21 has an internal problem and is not able to perform a correct measurement of the insulation of the motor vehicle 1; - 'VEHICLE FAULT': In this state, the insulation control unit 24 indicates to the user that there is a general problem with vehicle 1, which does not allow correct measurement of the electrical insulation. With reference to Figure 3, a possible state transition diagram that can be implemented by the isolation control unit 24 is now illustrated; this state diagram is simplified for reasons of simplicity of illustration and refers only to the main states that can be assumed by the isolation control unit 24 itself. Furthermore, in the example illustrated, it is assumed - 17 that the user interface elements 26 comprise at least: a first LED, suitable for indicating the status of the connection of the high voltage battery 5 to the high voltage bus 12; and a second LED, suitable for indicating the status of the detected electrical insulation. In detail, assuming that the service battery 16 is correctly connected in the vehicle 1 and supplies the 12V service power supply, powering, among other things, the insulation control unit 24, and furthermore that the connection terminals 15 are open, a first state assumed by the same insulation control unit 24 is indicated by 30 and corresponds to the aforementioned 'TESTING' state. In this state, for example, the first and second LEDs may assume a respective flashing color. From state 30, the diagram evolves into state 31, which corresponds to the aforementioned 'FAULT ISO - HV OFF' state, in case the second insulation monitoring device 21 has verified that the insulation resistance is below the pre-set insulation threshold Th. In this state, for example, the first LED is off and the second LED turns a solid red color. From the aforementioned state 30, the diagram instead evolves into state 32, which corresponds to the aforementioned state 'NO FAULT - HV OFF', in the case in which the second insulation monitoring device 21 has verified that the insulation resistance - 18 insulation is above the pre-set insulation threshold Th. In this state, for example, the first LED is off and the second LED turns solid green. From state 32, the diagram can evolve into state 31, as soon as the second insulation monitoring device 21 verifies that the insulation resistance is below the pre-set insulation threshold Th. Furthermore, from the same state 32, the diagram can evolve into state 33, which corresponds to the aforementioned 'VEHICLE FAULT' state, in the event that the insulation control unit 24 detects the presence of a fault in the vehicle 1 (for example, via corresponding information on the CAN bus 18). In this state, for example, the first LED can assume a fixed color, for example orange, and the second LED assume a respective fixed color, for example yellow, different from the green or red color assumed in the previous cases. From this state 33, the diagram can again evolve into state 32, in the event that the fault in vehicle 1 is no longer detected. Furthermore, from each of the above states 30-33, the diagram can evolve towards a state 34, which corresponds to the above 'ISO FAULT' state, in case the unit of - 19 insulation control 24 checks for an internal problem with the first or second insulation monitoring device 20, 21, thus not being able to perform a correct measurement of the vehicle's insulation. In this state, for example, the first LED may flash orange and the second LED may flash red. If, however, the connection terminals 15 are closed, the state diagram evolves towards state 36, which corresponds to the aforementioned 'NO FAULT - HV ON' state. Note that state 36 may eventually be the starting state of the state diagram, rather than the aforementioned state 30. Furthermore, from this state 36 one passes again to the aforementioned state 30 when the connecting terminals 15 are open. In this state 36, as discussed above, the insulation control unit 24 acts as an interface and the insulation verification is delegated to the first insulation monitoring device 20. In this state 36, for example, the first LED may turn a solid orange color and the second LED may turn a solid green color. From state 36, the diagram evolves into state 37, which corresponds to the aforementioned 'FAULT ISO - HV ON' state, in the case - 20 where the first insulation monitoring device 20 has verified that the insulation resistance is below the pre-set insulation threshold Th (the insulation control unit 24 receives this information from the CAN bus 18 and controls the user interface elements 26 accordingly). In particular, for example, the first LED takes on a fixed orange color and the second LED takes on a fixed red color. From the aforementioned state 36, the state diagram can instead evolve into state 38, which corresponds to the aforementioned 'VEHICLE FAULT' state, in the event that the insulation control unit 24 detects the presence of a fault in vehicle 1. In this state 38, for example, the first LED can assume a fixed color, for example orange, and the second LED assume a respective fixed color, for example yellow. From this state 38, the state diagram can evolve into state 37, in the case in which the first insulation monitoring device 20 verifies that the insulation resistance is below the pre-set insulation threshold Th; or into state 36, in the case in which the absence of faults in the vehicle 1 is verified. As discussed above, also from states 36-38 the - 21 diagram can evolve towards state 34, 'ISO FAULT', in the event that the insulation monitoring unit 24 detects the presence of an internal problem, in this case for the first insulation monitoring device 20. From state 34 you also return to state 36 if the problem with the insulation monitoring device is no longer present (and the connection terminals 15 are still closed). In a manner that is not described in detail so as not to burden the discussion, the state diagram may include further states and state transitions to also describe transitions between further states that may be assumed by the isolation control unit 24. Furthermore, the user interface elements 26 may include further LEDs with respective light signals; for example, a further LED may be used to indicate the connection of the service battery 16 to the motor vehicle 1. In this regard, Figure 3 shows a further portion of the state diagram, relating to the management of the situation in which the service battery 16 is disconnected from the motor vehicle 1. In this condition, the high voltage bus 12 is also not energized; consequently, the insulation control unit 24 manages the second device - 22 insulation monitoring 21 to check the insulation against high voltage. In detail, a first state, indicated by 40, corresponds to the aforementioned 'NO TESTING' condition; a third LED can be lit, for example with a fixed color, to indicate the condition of service battery 16 disconnected. In a possible implementation, the exit from this state 40 can be determined by the end of a first count of a counter internal to the insulation control unit 24, which therefore leads to the transition to a state 41, which corresponds to the aforementioned 'TESTING' state (this first count can correspond to a pre-set inactivity interval, or sleep, of the insulation control unit 24, for example lasting a couple of hours). In this state, the first and second LEDs can assume a respective flashing color; the third LED maintains the aforementioned fixed color. From state 41, the diagram evolves into state 42, which substantially corresponds to the aforementioned 'FAULT ISO HV OFF' state, in the case in which the second insulation monitoring device 21 has verified that the insulation resistance is below the pre-set insulation threshold Th. In this state, for example, the first LED is off and the - The second LED turns solid red; the third LED remains solid red. From the aforementioned state 41, the diagram instead evolves into state 43, which substantially corresponds to the aforementioned 'NO FAULT - HV OFF' state, in the case in which the second insulation monitoring device 21 has verified that the insulation resistance is above the pre-set insulation threshold Th. In this state, for example, the first LED is off and the second LED turns a solid green color; the third LED maintains the aforementioned solid color. From state 43, the diagram can evolve into state 42, as soon as the second insulation monitoring device 21 verifies that the insulation resistance is below the pre-set insulation threshold Th. Furthermore, from each of the aforementioned states 41-43, the diagram can evolve towards a state 44, which corresponds to the aforementioned 'ISO FAULT' state, in the event that the insulation control unit 24 detects the presence of a problem, in this case for the second insulation monitoring device 21, and is therefore unable to carry out a correct measurement of the vehicle's electrical insulation. In this state, for example, the first LED may flash orange and the second LED may flash red; the third LED - 24 maintains the aforementioned fixed color. From states 41-43, the diagram can also evolve again towards the initial state 40, in the event that the counter internal to the insulation control unit 24 reaches the end of a second count, typically having a duration shorter than the aforementioned first count (this duration corresponding to the execution of the insulation control, for example approximately 20 seconds). From what has been discussed, the advantages that this solution allows us to obtain clearly emerge. In any case, it should be noted that the solution described allows for complete and continuous monitoring over time of the vehicle's electrical insulation from the high voltage, in all possible conditions, including those in which the high voltage battery is not connected to the high voltage bus. The solution described therefore allows for an increase in the electrical safety of the vehicle against high voltage insulation losses, proving particularly advantageous when used in prototype vehicles. In particular, as discussed above, the interference-free cooperative interaction between the first and second isolation monitoring devices 20, 21 managed by the control unit is particularly advantageous. - 25 insulation control 24. Furthermore, the presence of the user interface elements 26 is advantageous, arranged in such a way as to always be visible to the user, both when on board 5 of the motor vehicle 1 and when outside the same motor vehicle 1. The solution described is also simple and economical to implement, generally not requiring substantial modifications to the vehicle 1. Finally, it is clear that modifications and variations can be made to what has been described without departing from the scope of the present invention, as defined in the attached claims. It should be noted in particular that the solution described 15 can also find advantageous application in series or production vehicles, in addition to the previously indicated case of prototype vehicles.

Claims

CLAIMS 1. Insulation monitoring system (10) for a motor vehicle (1) equipped with a high voltage battery (5) connected to a high voltage bus (12), comprising: a first insulation monitoring device (20), arranged inside the high voltage battery (5), and managed and controlled by a related BMS management module (9) of the high voltage battery (5); a second insulation monitoring device (21), arranged outside the high voltage battery (5);an insulation control unit (24), external to the high voltage battery (5) and operationally coupled to the second insulation monitoring device (21) to manage its operation, wherein said insulation control unit (24) is configured to implement an insulation verification system control logic (10) for a verification of the electrical insulation of said high voltage bus (12) which provides for an interaction, with a cooperation without mutual interference, between the first and the second insulation monitoring device (20, 21).; 2. System according to claim 1, wherein said high voltage battery (5) is selectively coupled to the high voltage bus (12) by means of connection terminals - 27 (15); and wherein said insulation control unit (24) is configured so as to implement said electrical insulation verification continuously, both when the connection terminals (15) of the high voltage battery (5) are closed, i.e. connected to the high voltage bus (12) of the motor vehicle (1), and when the connection terminals (15) are open, i.e. not connected to the high voltage bus (12).

3. System according to claim 1 or 2, wherein said insulation monitoring unit (24) is configured to implement said insulation verification via said second insulation monitoring device (21), independently of said first insulation monitoring device (20), in the case where said connection terminals (15) are open; and to operate as an interface towards said BMS management module (9) in the case where said connection terminals (15) are closed, said insulation monitoring unit (24) being in this case configured to receive from said BMS management module (9) a result of the insulation verification carried out via the first insulation monitoring device (20), independently of said second monitoring device (21).

4. System according to claim 2 or 3, wherein said insulation control unit (24) is operationally coupled to said BMS management module (9) via a CAN bus, Controller Area Network (18) inside said motor vehicle (1).

5. System according to claim 4, wherein said insulation control unit (24) is further configured to receive from said CAN bus (18) indications of faults of said motor vehicle (1) and to signal an impossibility of implementing said insulation check in the event of the occurrence of said faults.

6. System according to any of the preceding claims, wherein said insulation control unit (24) is further configured to signal an impossibility of implementing said insulation check in the event of problems with said first and / or second insulation monitoring devices (20, 21).

7. A system according to any of the preceding claims, further comprising one or more user interface elements (26), arranged inside and / or outside the motor vehicle (1) and controlled by said insulation control unit (24) to provide a user of the motor vehicle (1) with an indication of the status of the electrical insulation.

8. System according to claim 7, wherein said user interface elements (26) are configured to provide a visual indication of at least a lack of electrical insulation of said high voltage bus (12) with respect to a ground terminal of said motor vehicle (1) and comprise for this purpose one or more lighting elements, having one or more different colours.

9. System according to claim 8, wherein said lighting elements are arranged inside the passenger compartment of the motor vehicle (1), in correspondence with the dashboard and / or the windscreen, and outside the passenger compartment, in correspondence with the roof.

10. System according to any of the preceding claims, wherein said second insulation monitoring device (21) is arranged outside the high voltage battery (5) in a related box or container (22), connected to the high voltage bus (12); and wherein said insulation control unit (24) is arranged in a distinct and external position with respect to said container (22).

11. A system according to any preceding claim, wherein said motor vehicle (1) is further equipped with a low voltage service battery (16) adapted to be coupled to a service power line (17) within said motor vehicle (1); and wherein said insulation control unit (24) is coupled to the service battery (16) and is configured to implement said insulation verification via said second insulation monitoring device (21) even in the event that - 30 said service battery (16) is not connected to said service line in said motor vehicle (1).

12. System according to any of the preceding claims, wherein said first and second insulation monitoring devices (20, 21) are of the hardware type, based on a measurement of electrical impedance of said high voltage bus (12) with respect to a ground terminal of said motor vehicle (1).

13. Automotive control software storable in, and executable from, electronic processing resources and designed so that, when executed, the electronic processing resources become configured to implement the insulation control unit (24) of the insulation verification system (10) according to any of the preceding claims.

14. Motor vehicle (1), equipped with a high voltage battery (5) connected to a high voltage bus (12), comprising the insulation testing system (10) according to any of claims 1-12.

15. Motor vehicle according to claim 14, of prototype type.