METHOD FOR DIAGNOSING AN ELECTRICAL POWER SYSTEM FOR AN ELECTRIFIED VEHICLE

Abstract

The present invention relates to a method for diagnosing an electrical power system (15) for an electrified vehicle comprising an energy storage system (1), a voltage bus (5) generated by the storage system (1) and an ePTO electrical charging socket interface (6), the method comprising determining electrical parameters in post-driving when high voltage systems are deactivated and when the external power load (7) connected to the interface (6) only is activated, then performing an electrical fault diagnosis comprising verifying an insulation fault criterion of the electrical circuit (17) of the interface (7) consisting of generating an insulation fault alert if a first insulation resistance value is greater than a first resistance threshold and if, at the same time, the second insulation resistance value is less than a second resistance threshold. Figure 1.

Description

Title of the invention: METHOD FOR DIAGNOSING AN ELECTRICAL POWER SYSTEM FOR AN ELECTRIFIED VEHICLE

[0001] The field of the invention relates to a method for electrical diagnosis of an electrical power system for a vehicle comprising an electric power take-off interface, called an ePTO interface for “Electric Power Take Off” in English.

[0002] In food transportation applications requiring temperature control, utility vehicles include a dedicated interface, called an ePTO interface, for easily connecting an external refrigeration system. This type of interface allows for the supply of electricity operating at powers up to 100 kW and voltages of 1000 volts, for applications such as powering external accessories, hydraulic pumps, refrigeration systems or other equipment without the need for a separate generator or running the main engine.

[0003] In the case of electrified vehicles, these external power devices are generally connected to the vehicle's electrical power system to a voltage bus generated by the traction battery. This voltage bus operates at values ​​of several hundred volts. A specific communication mode is generally also provided through the vehicle's CAN bus ("Control Area Network") where the external load is authorized to operate in a read-only mode. This communication restriction aims to secure the vehicle's native systems against computer attacks. However, the impossibility of returning information through the CAN bus prevents the implementation of diagnostics necessary to monitor the electrical systems connected to the interface and trigger instantaneous protective measures if necessary, in particular the opening of the battery power circuit contactors.

[0004] Manufacturers are therefore seeking to improve the protection of users against electrical risks in an electrified vehicle power electrical system, supplying external loads. It is also necessary to improve the availability of the electrical system.

[0005] For this purpose, practitioners in the field recommend equipping external loads and the electrical system of vehicles with IMD ("Insulation Monitoring Device") type devices. However, interference problems between IMD devices may arise. It is therefore desirable to strengthen the protection measures.

[0006] Also known from the state of the art is patent document US-A1-20150346257 describing a current leak detection circuit for electrified vehicles, and more particularly detection circuits with robustness checks. This circuit uses voltage divider circuits coupled to the traction battery voltage bus and the vehicle chassis and is based on voltage comparison. This solution also provides a method for software monitoring of the traction battery charge state at two different times during a period when the vehicle is stationary. It should be noted that this diagnosis is not suitable for detecting an open circuit fault on a circuit connected to an ePTO interface.

[0007] There is therefore a need to strengthen the electrical protection for monitoring the power system of an electrified vehicle when an external power load is connected to it.

[0008] One objective of the invention is to overcome the aforementioned problems. One objective of the invention is to propose an electrical diagnostic solution for devices connected to an ePTO interface for which communication authorizations are restricted. Another objective is to propose a comprehensive diagnostic against electrical faults, in particular leakage currents and circuit breaks.

[0009] More specifically, the invention relates to a method for diagnosing an electrical power system for an electrified vehicle, in which the electrical system comprises an energy storage system, a voltage bus generated by the storage system and an electrical charging interface, designated ePTO interface, connected to the voltage bus and to which an electrical circuit comprising an external power load is connected.

[0010] According to the invention, the method comprises the following successive steps:

[0011] - monitoring information representative of a system shutdown request electric power,

[0012] - in case of detection of the stop request, the request to deactivate systems electrical powered by the voltage bus,

[0013] - the determination at a first instant, after the finalization of a first tempo rization following the time of the deactivation request, of a first value of the current of the energy storage system and of a first value of the insulation resistance of the energy storage system,

[0014] - the request to activate the external power load,

[0015] - the determination at a second instant, after the finalization of a second tempo rization following the time of the activation request, of a second value of the current of the energy storage system and of a second value of the insulation resistance of the energy storage system,

[0016] - performing an electrical fault diagnosis of the electrical circuit of the interface ePTO consisting of monitoring fault criteria, the diagnosis including a criterion insulation fault of the electrical circuit of the ePTO interface consisting of generating an insulation fault alert if the first insulation resistance value is greater than a first resistance threshold and if, at the same time, the second insulation resistance value is less than a second resistance threshold.

[0017] According to a variant, the diagnosis comprises an open circuit fault criterion of the electrical circuit of the ePTO interface consisting of generating an open circuit fault alert if the difference between the second current value and the first current value is less than a current consumption threshold.

[0018] According to a variant, the diagnosis comprises a criterion for detecting a current leak from the electrical circuit of the ePTO interface consisting of generating a current leak alert if the first current value is greater than a first current leak threshold or if the second current value is greater than a second current leak threshold.

[0019] According to a variant, the external power load is authorized to communicate with a communication network of the electrical power system in network read-only mode.

[0020] According to a variant, the external power load communicates with a communication network of the electrical power system via a secure gateway.

[0021] According to a variant, the first time delay has a predetermined duration at least equal to the time necessary to deactivate the electrical systems supplied by the voltage bus and for refreshing the current values ​​and the insulation resistance and the second time delay has a predetermined duration at least equal to the time necessary to activate the external power load and for refreshing the current values ​​and the insulation resistance.

[0022] It is further envisaged an electrical power system comprising an energy storage system, a voltage bus generated by the storage system and an electrical load socket interface, also designated ePTO interface, connected to the voltage bus and to which is connected an electrical circuit comprising at least one external power load, in which a control unit is configured for implementing the diagnostic method according to any one of the preceding embodiments.

[0023] Further contemplated is an electrified vehicle comprising such an electrical power system.

[0024] The invention further provides a computer program comprising instructions which, when the program is executed by a supervision control unit of an electrified vehicle, cause the latter to implement the diagnostic method according to any one of the preceding embodiments.

[0025] The invention further provides a computer-readable recording medium comprising instructions which, when executed by a computer, cause the computer to implement the diagnostic method according to any one of the preceding embodiments.

[0026] The diagnostic method has the advantage of improving the electrical protection for a high-voltage electrical system of an electrified vehicle. The method is configured to periodically trigger a diagnostic routine in a post-driving situation in order to improve the safety of the vehicle. It also makes it possible to improve the electrical safety of the circuits of an ePTO interface operating under security control against computer attacks.

[0027] Other characteristics and advantages of the present invention will appear more clearly on reading the detailed description which follows, comprising embodiments of the invention given as non-limiting examples and illustrated by the appended drawings, in which:

[0028] [Fig.l] schematically represents an electrical system for an electrified vehicle configured for the implementation of the diagnostic method according to the invention.

[0029] [Fig.2] schematically represents in the form of a functional block diagram an embodiment of the diagnostic method according to the invention.

[0030] The invention applies to electrical power systems, in particular for electrified vehicles, that is to say comprising an electrical motor machine and power electronics, with fully electric or hybrid motorization, preferably motor vehicles, but not only such as trucks, aircraft, tractors, bicycles, ships. More generally, the invention applies to any autonomous electrical power system.

[0031] In [Fig.l], an embodiment of the electrical power system 15 according to the invention is schematically represented. The electrical system 15 is a high-voltage system of an electrified vehicle intended for the connection of an external power load 7 via an electrical power interface 6 of the ePTO type.

[0032] The electrical system 15 comprises a power energy storage system 1 delivering a voltage of between 200 volts and 1000 volts. The energy storage system 1 comprises several electrochemical energy storage elements interconnected in series and / or parallel depending on the desired electrical capacities and specifications. An electrochemical energy storage element, also called an electrochemical cell, is a storage element having two electrical connection terminals and having a voltage of a few volts, most often between 2.3V and 4.2V, approximately. The cells can be of the Lithium-ion type (a lithium Nickel Manganese Cobalt oxide NMC or a lithium iron phosphate LFP can be cited at as examples of positive electrode active materials), Nickel Cadmium (Ni-cd), Nickel-Metal-Hydride (Ni-MH), Sodium-ion, Lead or even fuel cell for example. More precisely, a Lithium-ion cell is composed mainly of a porous positive electrode, a porous negative electrode, a separator and an electrolyte (which can be liquid, polymeric or solid). The operating principle of a Lithium-ion cell is based on the reversible exchange of Lithium ions between the two porous electrodes.

[0033] The electrical system 15 further comprises a voltage bus 5, commonly called a high voltage circuit or HV voltage bus (“High Voltage” in English) in the automotive field. The HV voltage bus 5 is generated by the storage system 1 and comprises two polarity lines delivering the voltage generated by the storage system 1. The HV voltage bus comprises at least one switch 3, called a relay or contactor, allowing the opening or closing of the HV voltage bus 5 in order to connect and disconnect the energy storage system from the electrical systems. The switch 3 can be arranged in the electrical system 15 in a manner integrated into the storage system 1 or external to the storage system 1.

[0034] The storage system 1 further comprises a control unit 2 comprising at least one computer, also designated by the acronym BMS (“Battery Management System”) or BTU (“Battery traction Unit”) in English. The control unit 2 is connected to a communication network 12, for example of the CAN type, for the exchange of information relating to the operation of the storage system 1 with the computers of the electrical system 15. This information from the storage system includes the parameters of current, voltage, insulation resistance, state of charge (“State of Charge”), charge and discharge current setpoint, temperature, state of health (“State of Health”), open circuit voltage (OCV), in particular.The storage system comprises sensors capable of measuring or determining the voltage for each storage element and the voltage of the HV voltage bus 5 between each polarity line forming the HV voltage bus. The storage system 1 further comprises a current sensor capable of measuring the charge and discharge current flowing on the HV voltage bus 5. Furthermore, as part of the diagnostic method, the control unit 2 is configured to measure the insulation resistance between conductive parts of the battery system and the chassis of the vehicle.

[0035] Conventionally, the insulation resistance is measured by a high voltage ohmmeter, an IMD type device (Insulation Monitoring Device) or by on-board functions of the control unit 2 from the measurements of voltage and current sensors at points of the high voltage circuit of the storage system 1 and of the HV voltage bus 5, in particular on each polarity line of the voltage bus HV 5. For example, a person skilled in the art is aware of patent document WO-Al-2015082825 describing a method for estimating insulation resistance making it possible to estimate at different times values ​​of the insulation resistance at points on the HV 5 voltage bus.

[0036] The communication network 12 is a multiplexed communication network configured to allow the exchange of information between the computers of this network. The on-board systems, also called native systems, of a vehicle collaborate in communication in read and write mode.

[0037] The electrical system 15 further comprises a control unit 13 for supervising the electrical system and all the computers connected to the communication network 12. The control unit 13 is designed to collect and transmit information from the computers of the electrical system 15. The control unit 13 may be the supervision computer of the electrified vehicle commonly called EVCU (“Electric Vehicle Control Unit”). Furthermore, for the purpose of diagnosing the electrical system, the control unit 13 comprises means for executing a diagnostic routine, for generating alerts relating to electrical faults as a function of information collected on the network 12 delivered by the storage system 1, in particular the insulation resistance, the current value and the voltage of the storage system. The control unit 13 further comprises means for recording a diagnostic log storing electrical fault codes in memory..

[0038] The electrical system 15 further comprises an electrical junction 4 whose function is to connect the HV voltage bus 5 to several electrical power interfaces 14, 16 and 6 operating at the voltage of the HV voltage bus 5.

[0039] In this embodiment, a first interface 6 is an ePTO electrical charging socket interface adapted to electrically supply an external power load 7 to the electrical system from the voltage delivered by the HV voltage bus 5. The first interface 6 is connected to an electrical circuit 17 comprising an electrical energy transfer connector 19. The connector is for example a “Plug and Play” type connection connector in English. For example, the connector may be of the “HVA 280 High-Voltage Interconnection System” type from the “TE Connectivity®” brand, or of the type of the ISO 23316-2:2023 standard “Tractors and machinery for agriculture and forestry — Electrical high-power interface 700 V DC / 480 V AC — Part 2: Physical interface”. The type of connector used is however not limiting of the invention.

[0040] The first interface 6 further comprises a logical communication link 18 making it possible to connect a computer 8 of the external power load 7 to the communication network 12. The connector of the logical link 18 is adapted for a CAN type communication protocol in order, for example, to activate or deactivate the external power load depending on a state of the electrical system established from information circulating on the communication network 12. In a variant, the circuit 17 may comprise a DC / AC type voltage converter making it possible to supply an external power load with alternating voltage.

[0041] Preferably, the communication link 18 between the external power load and the communication network 12 includes protection against computer attacks. In one protection variant, the external power load 7 is authorized to communicate with the communication network 12 in read mode of the network 12 only. Other computer protection variants are conceivable, such as, for example, the external power load 7 communicating with the communication network via a secure gateway. It is envisaged that the two protection variants can be combined.

[0042] A second interface 14 is provided for powering a voltage conversion and charging device 10 of the energy storage system 1 from an external energy source. This device 10 implements functions of a DC / DC converter and an on-board charger called OBC (“On-Board Charger”). This device comprises a computer 11 capable of communicating with the communication network 12. Optionally, the junction 4 is adapted to transfer energy from the storage system and / or from the charger 10 to the external power load 7 through the ePTO interface 6. A third interface 16 is provided for connecting an HV electrical system, for example a water heater or a compressor.

[0043] The principle of the invention is a diagnosis aimed at improving the electrical safety of an electrical power system comprising an interface called ePTO to which an external power load is connected operating with communication restrictions on the vehicle's CAN bus.

[0044] In [Fig.2], an embodiment of the diagnostic method is represented in the form of a functional block diagram. The method is described in the context of an electrified vehicle application comprising an electrical power system comprising an ePTO interface to which an external power load is connected. The diagnosis is controlled periodically in the form of a routine triggered in a post-driving situation, at each stop of the vehicle or periodically according to a frequency predetermined by the vehicle supervision control unit.

[0045] The electrical system control unit is provided with an integrated circuit computer and electronic memories, the computer and the memories being configured to execute the diagnostic method according to the invention. But this is not obligatory. Indeed, the computer could be external to the control unit, while being coupled to the latter. In the latter case, it can itself be arranged in the form of a dedicated calculator including a possible dedicated program, for example. Consequently, the control unit, according to the invention, can be produced in the form of software modules (or computer modules (or even "software")), or electronic circuits (or "hardware"), or even a combination of electronic circuits and software modules.

[0046] In a first step SI, the vehicle is started. A “KEY-ON” information of the CAN communication network is in an active state. The opening and closing switches of a power circuit of the energy storage system are closed. The energy storage system supplies the circuits connected to the HV voltage bus. In this embodiment, the circuits comprise the HV systems, a DC / DC voltage converter for supplying an on-board network, a DC / AC voltage converter for supplying an electrical driving machine and an electrical circuit connected to an ePTO interface to which an external power load is connected.

[0047] The method comprises a second step S2 comprising the monitoring of information representative of a request to shut down the electrical system, i.e. to stop the vehicle or a so-called “post-driving” situation. More precisely, it comprises the monitoring of “Key-OFF” information from the CAN bus, a change of state from “Key-ON” to “Key-OFF”, and preferably furthermore of information representative of the absence of a request to maintain closure of the circuit contactor(s) of the HV voltage bus. The information is determined from information circulating on the CAN communication network.

[0048] In the event of detection of a request to shut down the electrical system, the method comprises a third following step S3 comprising a request to deactivate the HV electrical systems supplied by the HV voltage bus of the electrical system, for example the systems supplied with high voltage (compressor, water heater) and the external power loads. The deactivation of the systems is maintained for a time delay TL. The time delay T1 is configured to a duration allowing the shutdown of all the electrical systems supplied by the HV voltage bus as well as the refreshing of the parameters of the control unit of the storage system comprising the parameters of the insulation resistance of the storage system, on one or more points of the HV voltage bus, and the refreshing of the current value of the storage system.The duration of the time delay Tl is a value calibrated according to the HV electrical systems and recorded in the memory of the supervision control unit.

[0049] The method then comprises a fourth step S4 of verifying the completion of the time delay TL.

[0050] Then, the method comprises a fifth step of determining S5 at a first time t1, after the completion of the first time delay, a first value of the current IBAT_t1 of the energy storage system and a first value of the insulation resistance RINS_t1 of the energy storage system. These values ​​can be determined by the control unit of the storage system and are recorded in the memory of the supervision control unit for diagnostic purposes.

[0051] Then, the method comprises in a sixth step the activation request S6 of the external power load connected to the ePTO interface. The activation is controlled only for a load of the ePTO interface. The activation request may comprise the activation of all the external loads connected to an ePTO interface of the electrical system, and in particular the loads operating with communication restrictions with the CAN communication network. The activation request is maintained for a time delay T2.

[0052] The time delay T2 is configured to a duration sufficient to activate the external power loads as well as for the refreshing of the parameters of the control unit of the storage system including the parameters of the insulation resistance of the storage system, on points of the HV voltage bus, and the refreshing of the current value of the storage system. The duration of the time delay T2 is a value calibrated according to the HV electrical systems and recorded in memory of the supervisory control unit.

[0053] Next, the method then comprises a seventh step S7 of verifying the completion of the time delay T2.

[0054] Then, the method comprises an eighth step S8 of determining at a second time t2, after the completion of the second time delay T2 following the time of the activation request, a second value of the current IBAT_t2 of the energy storage system and a second value of the insulation resistance RINS_t2 of the energy storage system. These values ​​can be determined by the control unit of the storage system and are recorded in the memory of the supervision control unit for diagnostic purposes.

[0055] Then, the method comprises a phase of diagnosing an electrical fault in the electrical circuit of the ePTO interface consisting of monitoring fault criteria. More precisely, in a ninth step S9, the execution of the diagnosis comprises the verification of a first insulation fault criterion of the electrical circuit of the ePTO interface consisting of generating an insulation fault alert in a tenth step S10 if the first insulation resistance value RINT_tl is greater than a first resistance threshold SRI and if, at the same time, the second insulation resistance value RINS_t2 is less than a second resistance threshold SR2. SRI is the minimum insulation resistance value for which it is established that there is no insulation fault. SR2 is the insulation resistance value for detecting a so-called safety insulation fault. In an HV network, a safety threshold is generally set at 500 ohms per volt.

[0056] The purpose of step S9 is to verify that the electrical power system operates normally, without insulation fault, when all the HV systems are deactivated, and that an insulation fault is detected at time t2, when only the systems of the ePTO interface are activated. This criterion allows the vehicle control unit to detect an insulation fault of the ePTO interface even when the latter interface is not able to return information via the CAN bus.

[0057] In an example of a calibration configuration for a 400 volt HV network, the first threshold SRI is equal to 800 KOhms and the second threshold SR2 is equal to 200 KOhms.

[0058] If the test result is positive, the alert is generated in step S10. A code identifying the insulation fault is recorded and communicated to a diagnostic log. If the result is negative, in an eleventh step SI 1, this diagnostic conformity status is recorded.

[0059] Furthermore, the diagnosis comprises, in a twelfth step S12, the verification of an open circuit fault criterion of the electrical circuit of the ePTO interface consisting of generating, in a thirteenth step S13, an open circuit fault alert if the difference between the second current value IBAT_t2 and the first current value IBAT_tl is less than an open circuit threshold SCC. This verification compares the situation at time t1 where all the electrical systems are deactivated and the situation at time t2 where only the loads connected to the ePTO interface are activated. If this difference is less than the threshold SCC, this indicates that at least one of the loads connected to the ePTO circuit is not powered. This is a sign of the presence of an open circuit fault.

[0060] The SCC threshold is the minimum current value to detect an open circuit fault. This value must be equivalent to the absolute sum of the minimum currents of the external power loads connected to the ePTO interface. The SCC value is calibrated in the memory of the supervisory control unit.

[0061] If the test result is positive, the alert is generated in step S13. A code identifying the open circuit fault is recorded and communicated to a diagnostic log. If the result is negative, in a fourteenth step S14, this diagnostic compliance status is recorded.

[0062] Furthermore, the diagnosis comprises, in a fifteenth step S15, the verification of a current leakage criterion of the electrical circuit of the ePTO interface consisting of generating, in a sixteenth step S16, a current leakage alert if the first value current value IBAT_tl is greater than a first current leakage threshold SFC1 or if the second current value IBAT_t2 is greater than a second current leakage threshold SFC2.

[0063] The threshold SFC1 is the threshold for detecting a current leak on the HV voltage bus when all the consumers connected to the HV voltage bus are deactivated, the electrical machine, the DC / DC converter, the HV consumers and the ePTO interface, in particular. The threshold SFC2 is the threshold for detecting a current leak on the HV voltage bus when an external power load connected to the ePTO interface is activated. The values ​​of SFC1 and SFC2 are calibrated in memory of the supervisory control unit.

[0064] If the test result is positive, the alert is generated in step S16. A code identifying the current leakage fault is recorded and communicated to a diagnostic log. If the test result is negative, in a seventeenth step S17, this diagnostic compliance status is recorded.

[0065] The diagnosis may execute only one electrical fault criterion among the three criteria or only two criteria among the three criteria. Preferably, all three criteria will be checked at each execution of the diagnostic routine.

[0066] Finally, the method comprises a final step S18 consisting of triggering a request to deactivate the external power load connected to the ePTO interface, and opening the circuit switches of the HV voltage bus and finalizing the shutdown of the vehicle's power electrical system. The diagnostic routine is finalized and the results are stored in the diagnostic log memory. The electrical system is shut down. If a fault is present, the ePTO interface is deactivated until the fault is resolved.

[0067] The electrical system has been described for an example of an electrified vehicle architecture. It is envisaged that the diagnostic method will be applicable to other variants of electrical architectures.

[0068] The invention is described in the above by way of example. It is understood that the person skilled in the art is able to produce different variant embodiments of the invention by associating, for example, the different characteristics above taken alone or in combination, without departing from the scope of the invention.

Claims

Claims

1. Method for diagnosing an electrical power system (15) for an electrified vehicle, in which the electrical system comprises an energy storage system (1), a voltage bus (5) generated by the storage system (1) and an electrical charging socket interface (6), designated ePTO interface, connected to the voltage bus (5) and to which an electrical circuit (17) comprising an external power load (7) is connected, the method being characterized in that it comprises the following successive steps: - monitoring (S2) information representative of a request to stop the electrical power system (1), - in the event of detection of the stop request, the request to deactivate (S3) electrical systems supplied by the voltage bus (5), - determining (S5) at a first instant, after the finalization (S4) of a first time delay following the instant of the deactivation request, a first value of the current (IBAT_tl) of the energy storage system (1) and a first value of the insulation resistance (RINS_tl) of the energy storage system (1), - the activation request (S6) of the external power load (7), - determining (S8) at a second instant, after the finalization (S7) of a second time delay following the instant of the activation request, a second value of the current (IBAT_t2) of the energy storage system (1) and a second value of the resistance isolation (RINS_t2) of the energy storage system (1),- performing an electrical fault diagnosis of the electrical circuit of the ePTO interface consisting of monitoring fault criteria, the diagnosis comprising verifying (S9) an insulation fault criterion of the electrical circuit (17) of the ePTO interface (7) consisting of generating (S 10) an insulation fault alert if the first insulation resistance value (RINS_tl) is greater than a first resistance threshold (SRI) and if, at the same time, the second insulation resistance value (RINS_t2) is less than a second resistance threshold (SR2).,

2. A diagnostic method according to claim 1, wherein the diagnostic comprises verifying (S 12) an open circuit fault criterion of the electrical circuit (17) of the ePTO interface (7) by generating (S 13) an open circuit fault alert if the difference between the second current value (IBAT_t2) and the first current value (IBAT_tl) is less than a current consumption threshold (SCC).

3. Diagnostic method according to claim 1 or 2, wherein the diagnosis comprises the verification (S 15) of a criterion for detecting a current leakage of the electrical circuit (17) of the ePTO interface (7) consisting of generating (S 16) a current leakage alert if the first current value (IBAT_tl) is greater than a first current leakage threshold (SFC1) or if the second current value is greater than a second current leakage threshold (SFC2).

4. A diagnostic method according to any one of claims 1 to 3, wherein the external power load (7) is allowed to communicate with a communication network (12) of the electrical power system (15) in network read-only mode.

5. A diagnostic method according to any one of claims 1 to 4, wherein the external power load (7) communicates with a communication network (12) of the electrical power system (15) via a secure gateway.

6. Diagnostic method according to any one of claims 1 to 5, wherein the first time delay has a predetermined duration at least equal to the time required to deactivate the electrical systems supplied by the voltage bus (5) and for refreshing the current values ​​(IBAT_tl) and the insulation resistance (RINS_tl) and the second time delay has a predetermined duration at least equal to the time required to activate the external power load (7) and for refreshing the current values ​​(IBAT_t2) and the insulation resistance (RINS_t2).

7. Electrical power system (15) comprising an energy storage system (1), a voltage bus (5) generated by the storage system (1) and an electrical charging interface (6), also referred to as an ePTO interface, connected to the voltage bus (5) and to which is connected an electrical circuit (17) comprising at least one external power load (7), characterized in that it further comprises a control unit (13) configured for implementing the diagnostic method according to any one of claims 1 to 6.

8. An electrified vehicle comprising an electrical power system (15) according to claim 7.

9. A computer program comprising instructions which, when the program is executed by a supervisory control unit of a electrified vehicle, lead it to implement the diagnostic method according to any one of claims 1 to 6.

10. A computer-readable recording medium comprising instructions which, when executed by a computer, cause the computer to carry out the diagnostic method according to any one of claims 1 to 6.

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