BI-DIRECTIONAL ON-BOARD VEHICLE CHARGER AND METHOD FOR DIAGNOSING THE OPERATION OF A RELAY ON THE ON-BOARD CHARGER

Abstract

One aspect of the invention relates to a bidirectional on-board charger 2 for a vehicle 1 comprising: A bidirectional AC-DC converter 8 arranged to supply power to an electrical outlet 6 of an external electrical device; Means for detecting an electrical insulation fault 9 connected to a phase line 12 and a neutral line 13 of said electrical outlet 6; A switch 16 disposed on said phase line 12; A switching means 18 arranged to drive the switch 16 between a first position P1 in which the means 9 are connected to the outlet 6 and a second position P2; A resistor 20 electrically connected, when the switch 16 is in the second position P2, to the switch 16 and to a ground 10 of the vehicle. Figure to be published with the abstract: Figure 1

Description

Title of the invention: BI-DIRECTIONAL VEHICLE ON-BOARD CHARGER AND METHOD DIAGNOSTIC OF THE FUNCTIONING OF A RELAY IN AN ON-BOARD CHARGER - TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a bidirectional on-board charger for a motor vehicle arranged to diagnose the operation of at least one first relay included in said on-board charger, and to a method for diagnosing the operation of at least one first relay included in the on-board charger.

[0002] The invention applies to electrified vehicles, enabling, in particular, the power supply of external equipment from energy stored in a high-voltage battery of the vehicle. This use case is commonly referred to by the English expression "Vehicle-To-Load" (V2L). TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] Electrified vehicles equipped with an on-board charger are known, configured to recharge a high-voltage battery, known as the traction battery, and to supply electrical power, from the energy stored in the high-voltage battery, to a low-voltage battery, known as the auxiliary battery, the vehicle's on-board electrical system, and external electrical equipment, for example, a computer whose power cord is connected to a power outlet in the vehicle. Such an on-board charger is commonly referred to by those skilled in the art as the OBC, for "On-Board Charger."

[0004] This on-board charger usually includes an alternating current / direct current converter, known as AC / DC for "Alternating Current / Direct Current" in English, arranged to: • when charging the high-voltage battery via an external power source to the vehicle, convert an alternating voltage of 220V or 110V (depending on the electrical standard of the region) supplied by the external power source, to a compatible direct current voltage of the high-voltage battery, the external power source being able to be a domestic socket, a fixed domestic station (commonly called a "Wallbox" in English) or a charging station at a motorway station; • When external electrical equipment connected to the power outlet is connected to the vehicle, convert the DC voltage stored in the high-voltage battery to AC voltage, for example single-phase type, to power the external electrical equipment connected to the power outlet.

[0005] To ensure the safety of vehicle users, the on-board charger also includes means for detecting an electrical insulation fault between the vehicle's electrical ground (Class A electrical standard) and the vehicle's phase lines (Class B electrical standard). These means are usually designated by the acronym IMD for "Insulation Monitoring Device".

[0006] These means for detecting an insulation fault are, in particular, electrically connected to a phase line and a neutral line of the power supply socket. In order to verify the proper electrical insulation of the power supply socket with respect to the vehicle's electrical ground, formed in particular by the ground of the low-voltage battery, the means for detecting an electrical insulation fault inject a leakage current on the phase line and measure a voltage resulting from the impedance between the vehicle's phase line and the electrical ground of the low-voltage battery. If the measured impedance is less than a threshold impedance value, then the means for detecting an electrical insulation fault deduce the presence of an insulation fault in the power supply socket. The supply of current from the AC-DC converter is then prohibited.

[0007] Furthermore, in order to ensure the safety of a user, it is prohibited to connect this power supply plug to an external electrical device or to a power source to charge the battery while the high-voltage battery is being recharged on a charging station.

[0008] To ensure this functionality, the phase line of the power supply socket includes a switch actuated by a switching means for connecting or disconnecting the phase line from the AC-DC converter. This switch, together with the switching means, forms a relay. Thus, when the vehicle is connected to an external charging station to recharge the high-voltage battery, the power supply socket intended to power an external electrical device is disconnected from the AC-DC converter by opening the switch. It is further known to connect a first voltage measuring device downstream of the switch and a second voltage measuring device upstream of the switch. Thus, if these two voltage measuring devices measure two different voltage values, this indicates that the switch is open. Conversely, if both voltage measuring devices measure identical voltage values, this indicates that the switch is closed. This strategy allows verification that there is no fault in the relay. However, this solution requires two voltage measuring devices and is obviously expensive.

[0009] The cost is further increased when the vehicle has two power supply sockets for devices external to the vehicle. It is indeed necessary to install two additional voltage measurement devices to ensure the proper functioning of the second relay. Summary of the invention

[0010] The invention offers a solution to the problem mentioned above, by proposing an inexpensive alternative solution for detecting a possible malfunction of the relay present on the phase line of the power supply socket of electrical devices external to the vehicle.

[0011] In this context, the invention thus relates, in its broadest sense, to a bidirectional on-board charger for a motor vehicle, the on-board charger comprising: • A bidirectional AC-DC converter, arranged to convert: • A direct current from a high-voltage vehicle battery into an alternating current suitable for powering a first electrical power outlet; • An alternating current from a power source external to the vehicle connected to the first electrical power outlet into a direct current suitable for charging the high-voltage battery; • Means for detecting an electrical insulation fault between at least one phase line of the vehicle and an electrical mass of the vehicle, these means for detecting an electrical insulation fault being electrically connected to a first phase line and to a first neutral line of the first electrical supply outlet; • A first switch placed on the first phase line; • A first switching method arranged to control the first switch between a first closed position in which the means for detecting an electrical insulation fault are electrically connected to the first electrical supply outlet and a second position in which the first switch is open, said first switch and switching means together forming a first relay; • a first resistor electrically connected, when the first switch is in the second position, to the first switch and to the electrical ground of the vehicle.

[0012] Thus, if the means for detecting an electrical insulation fault emit a leakage current on the first phase line, they are able to determine an impedance value present between the phase line and the vehicle ground. This impedance value determined by the means for detecting an electrical insulation fault must be different depending on whether the switch is in the first position (in other words, the leakage current does not pass through the first resistor) or whether the switch is in the second position and the leakage current passes through the first resistor.

[0013] This on-board charger therefore makes it possible to detect a possible malfunction of the first relay without the need to add a voltage measuring device downstream of the first switch and a voltage measuring device upstream of the first switch. The on-board charger uses means for detecting electrical insulation faults already present in the charger to diagnose the operation of the first relay. Compared to those of the prior art, the cost of this on-board charger is therefore reduced.

[0014] In addition to the characteristics just mentioned in the preceding paragraph, the on-board charger according to this aspect of the invention may have one or more complementary characteristics from among the following, considered individually or according to all technically possible combinations.

[0015] According to a non-limiting implementation of the invention, • the AC-DC converter is further arranged to convert a DC current from the vehicle's high-voltage battery into an AC current suitable for powering a second power outlet for an electrical device external to the vehicle; • The means for detecting an electrical insulation fault are electrically connected to a second phase line and a second neutral line of the second electrical supply outlet; • The on-board charger also includes a second switch located on the second phase line; • A second switching means arranged to operate the second switch between a first closed position in which the means for detecting an electrical insulation fault are electrically connected to the second power supply outlet and a second position in which the second switch is open, the second switch and switching means together forming a second relay; • A second resistor electrically connected, when the second switch is in the second position, to the second switch and to the vehicle's electrical ground.

[0016] According to a non-limiting implementation of the invention, the first resistor and the second resistor have different impedance values ​​from each other.

[0017] Another aspect of the invention relates to an electric or hybrid vehicle comprising an on-board charger according to any one of the aforementioned implementations of the invention.

[0018] A different aspect of the invention relates to a method for diagnosing the operation of at least one first relay comprising an on-board vehicle charger according to any one of the aforementioned embodiments of the invention, the method comprising the following steps, carried out when the AC-DC converter is inactive: • Control, via the first switching means, the first switch to bring it into its second position; • Generate, via the means of detecting an electrical insulation fault, a leakage current on the first phase line; • Determine, via the means of detecting an electrical insulation fault, a first impedance value on the first phase line as a function of the leakage current; • If the first impedance value is less than a first predetermined impedance threshold, drive, via the first switching means, the first switch to bring it into its first position; • Determine, via the means of detecting an electrical insulation fault, a second impedance value on the first phase line as a function of the leakage current; • If a difference between the first impedance value and the second impedance value is less than a second predetermined impedance threshold, determine a malfunction of the first relay; • If the difference between the first impedance value and the second impedance value is greater than a third predetermined impedance threshold, determine proper operation of the first relay.

[0019] According to a non-limiting embodiment of the invention, the process comprises the steps of: • Control, via the second switching means, the second switch to bring it into its second position; • Generate, via the means of detecting an electrical insulation fault, a leakage current on the second phase line; • Determine, via the means of detecting an electrical insulation fault, a first impedance value on the second phase line as a function of the leakage current; • If the first impedance value is less than the first predetermined impedance threshold, drive, via the second switching means, the second switch to bring it into its first position; • Determine, via the means of detecting an electrical insulation fault, a second impedance value on the second phase line as a function of the leakage current; • If the difference between the first impedance value and the second impedance value is less than the second predetermined impedance threshold, determine a malfunction of the second relay; • If the difference between the first impedance value and the second impedance value is greater than the third predetermined impedance threshold, determine proper operation of the second relay.

[0020] According to a non-limiting implementation of the invention, • When the first impedance value of the first phase line is greater than the first predetermined impedance threshold, the process includes a step to determine proper operation of the first relay; • When the first impedance value of the second phase line is greater than the first predetermined impedance threshold, the method includes a step to determine proper operation of the second relay.

[0021] According to a non-limiting embodiment of the invention, the process comprises the steps of: • Activate, via on-board charger control means, the bidirectional AC-DC converter; • Control, via the first switching means, the first switch to bring it into its second position; • Generate, via the means of detecting an electrical insulation fault, a leakage current on the first phase line; • Determine, via the means of detecting an electrical insulation fault, a first impedance value on the first phase line as a function of the leakage current; • Control, via the first switching means, the first switch in the first position; • Determine, via the means of detecting an electrical insulation fault, a second impedance value on the first phase line as a function of the leakage current; • If the difference between the first impedance value and the second impedance value determined is less than the second predetermined impedance threshold, determine a malfunction of the first relay; • If the difference between the first and second determined impedance values ​​is greater than the third predetermined impedance threshold, determine proper operation of the first relay.

[0022] According to a non-limiting embodiment of the invention, the process comprises the steps of: • Control, via the second switching means, the second switch to bring it into its second position; • Generate, via the means of detecting an electrical insulation fault, a leakage current on the second phase line; • Determine, via the means of detecting an electrical insulation fault, a first impedance value on the second phase line as a function of the leakage current; • To control, via the second switching means, the second switch in the first position; • Determine, via the means of detecting an electrical insulation fault, a second impedance value on the second phase line as a function of the leakage current; • If the difference between the first and second determined impedance values ​​is less than the second predetermined impedance threshold, determine a malfunction of the second relay; • If a difference between the first impedance value and the second determined impedance value is greater than the second predetermined impedance threshold, determine proper operation of the second relay.

[0023] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0024] The figures are presented for illustrative purposes only and are in no way limiting of the invention.

[0025] [Fig-1] illustrates a non-limiting example of an embodiment of an on-board charger according to the invention.

[0026] [Fig.2] illustrates the steps of a diagnostic method for the operation of at least one first relay included in an on-board vehicle charger according to the invention. DETAILED DESCRIPTION

[0027] Fig. 1 shows a non-limiting example of an embodiment of an electric vehicle 1 equipped with an on-board charger 2 according to the invention.

[0028] The electric vehicle 1 includes a high-voltage battery 3, a low-voltage battery 4 used in particular to power control means 5 of the on-board charger 2, a first electrical power outlet 6 and a second electrical power outlet 7.

[0029] The first power supply socket 6 is bidirectional and allows, depending on the times, either to charge the high-voltage battery 3, or to power an electrical device external to the vehicle 1.

[0030] The second power supply socket 7 allows, for its part, to power an electrical device external to the vehicle 1.

[0031] The external electrical device is, for example, an electrical appliance operating at an alternating current supply voltage in accordance with known electrical standards (110V, 230V, or 240V). The external electrical device has a plug connected by a cable to the equipment and is plugged into the first or second electrical outlet 6, 7 of the vehicle 1 dedicated for this purpose. Such an external electrical device may be, for example, a computer, a tablet, or a kettle.

[0032] The first and second power supply sockets 6, 7 can be electrically isolated from the high-voltage battery 3 via galvanic isolation. Furthermore, the first and second power supply sockets 6, 7 can be electrically isolated from the low-voltage battery 4 and the control means 5 via galvanic isolation.

[0033] The on-board charger 2 includes a bidirectional AC-DC converter 8 arranged to convert a DC current from the high-voltage battery 3 into an AC current suitable for powering the first power outlet 6 as well as the second power outlet 7.

[0034] The bidirectional AC-DC converter 8 is also arranged to convert an alternating current from an external power source to the vehicle connected to the first power outlet 6 into a direct current suitable for charging the high-voltage battery 3.

[0035] The AC-DC converter 8 is, for example, a power factor correction converter, designated an AC-DC converter (for "Power Factor Correction"). The on-board charger 2 further includes means for detecting an electrical insulation fault 9 between at least one phase line of the vehicle 1 and an electrical ground 10 of the vehicle 1. These means 9 are usually referred to by the acronym IMD for "Insulation Monitoring Device" in English.

[0036] These means for detecting an electrical insulation fault 9 are electrically connected to a first phase line 12 and a first neutral line 13 connected to the first electrical supply socket 6 as well as to a second phase line 14 and a second neutral line 15 connected to the second electrical supply socket 7.

[0037] The on-board charger 2 further comprises a first switch 16 arranged on the first phase line 12 and a second switch 17 arranged on the second phase line 14.

[0038] The on-board charger 2 also includes a first switching means 18 arranged to drive the first switch 16 between a first closing position PI in which the means for detecting an electrical insulation fault 9 are electrically connected to the first power supply socket 6 and a second opening position P2.

[0039] The first switch 16 and the first switching means 18 together form a first relay RL

[0040] The on-board charger 2 also includes a second switching means 19 arranged to drive the second switch 17 between a first closing position PI in which the means for detecting an electrical insulation fault 9 are electrically connected to the second power supply socket 7 and a second opening position P2.

[0041] The second switch 17 and the second switching means 19 together form a second relay R2.

[0042] According to the illustrated embodiment, the on-board charger 2 further comprises: • A first resistor 20 electrically connected, when the first switch 16 is in the second opening position P2, to the first switch 16 and to the electrical ground 10 of the vehicle 1; • A second resistor 21 electrically connected, when the second switch 17 is in the second open position P2, to the second switch 17 and to the electrical ground 10 of the vehicle 1.

[0043] The on-board charger 2 also includes control means 5 for the on-board charger 2. These control means 5 control in particular the first and second switching means 18, 19 as well as the alternating-direct current converter 8.

[0044] [Fig.2] illustrates a non-limiting embodiment of a method 100 according to the invention carried out by the on-board charger 2 according to the invention as illustrated in [Fig.1].

[0045] According to a non-limiting implementation, the steps of the method 100 below are carried out when the AC-DC converter 8 is inactive, that is to say when the AC-DC converter 8 is not supplying electrical power to any of the first and second power outlets 6, 7 and is not receiving electrical power from an external power supply source connected to the first power outlet 6.

[0046] Process 100 comprises the steps of: Control 101, via the first switching means 18, the first switch 16 to bring it into its second open position P2, and Control 101', via the second switching means 19, the second switch 17 to bring it into its second opening position P2.

[0047] Thus, the first switch 16 is electrically connected to the first resistor 20 and the second switch 17 is electrically connected to the second resistor 21.

[0048] The process 100 then comprises the steps of: Generate 102, via the means for detecting an electrical insulation fault 9, a leakage current on the first phase line 12; and Generate 102', via the means for detecting an electrical insulation fault 9, a leakage current on the second phase line 14.

[0049] According to a non-limiting example embodiment, the leakage current can for example be between 10 pA and 50 pA.

[0050] Then, Depending on the leakage current flowing on the first phase line 12, the process 100 performs a step of determining 103, via the means for detecting an electrical insulation fault 9, a first impedance value on the first phase line 12; and Depending on the leakage current flowing on the second phase line 14, the process 100 performs a step of determining 103', via the means for detecting an electrical insulation fault 9, a first impedance value on the second phase line 14.

[0051] When the first impedance value of the first phase line 12 is greater than a first predetermined impedance threshold, the process 100 includes a step of determining 104 the proper functioning of the first relay RL. Similarly, when the first impedance value of the second phase line 14 is greater than the first predetermined impedance threshold, the process 100 includes a step of determining 104' the proper functioning of the second relay R2.

[0052] By way of non-limiting example, the first predetermined impedance threshold is between 1 Mega-Ohms and 10 Mega-Ohms.

[0053] Conversely, if the first impedance value is lower than the first predetermined impedance threshold, the method 100 performs the steps of: • To drive 105, via the first switching means 18, the first switch 16 into the first closed position PI, and then to determine 106, via the electrical insulation fault detection means 9, a second impedance value on the first phase line 12 as a function of the leakage current; and • Drive 105', via the second switching means 19, the second switch 17 in the first PI closing position, then determine 106', via the electrical insulation fault detection means 9, a second impedance value on the second phase line 14 as a function of the leakage current.

[0054] The method 100 then comprises the steps, carried out by the means for detecting an electrical insulation fault 9 or by the control means 5, of: • On the first phase line 12, if there is a difference between the first impedance value and the second impedance value determined: • Below a second predetermined impedance threshold, determine 107 a malfunction of the first RI relay; • Above a third predetermined impedance threshold, determine 108 the proper functioning of the first RI relay; • On the second phase line 14, if there is a difference between the first impedance value and the second impedance value determined: • Below the second predetermined impedance threshold, determine 107' a malfunction of the second relay R2; • Above the third predetermined impedance threshold, determine 108' the proper functioning of the second relay R2.

[0055] According to a non-limiting embodiment, the second predetermined impedance threshold and the third predetermined impedance threshold are equal.

[0056] When a malfunction of one of the relays RI, R2 is detected, the control means 5 can deactivate the AC-DC converter 8 in order to avoid a possible risk of electrocution for the users of the vehicle 1.

[0057] According to a non-limiting implementation, the method 100 includes a step of activating 109, via the control means 5, the AC-DC converter 8, for example when an external electrical device is plugged into the first power outlet 6.

[0058] Then, for example when the external electrical device is disconnected, the process 100 comprises the steps of: • Control 110, via the first switching means 18, the first switch 16 to bring it into its second position P2; • Control 110', via the second switching means 19, the second switch 17 to bring it into its second position P2.

[0059] The process 100 then comprises the steps of: • Generate 111, via the means for detecting an electrical insulation fault 9, a leakage current on the first phase line 12; and • Generate 111', via the means for detecting an electrical insulation fault 9, a leakage current on the second phase line 14.

[0060] Then, • Depending on the leakage current flowing on the first phase line 12, the process 100 performs a step of determining 112, via the means for detecting an electrical insulation fault 9, a first impedance value on the first phase line 12; and • Depending on the leakage current flowing on the second phase line 14, the process 100 performs a step of determining 112', via the means for detecting an electrical insulation fault 9, a first impedance value on the second phase line 14.

[0061] Process 100 also performs the steps of: • To drive 113, via the first switching means 18, the first switch 16 into the first closed position PI, and then to determine 114, via the means for detecting an electrical insulation fault 9, a second impedance value on the first phase line 12 as a function of the leakage current; and • Drive 113', via the second switching means 19, the second switch 17 in the first PI closing position, then determine 114', via the electrical insulation fault detection means 9, a second impedance value on the second phase line 14 as a function of the leakage current.

[0062] The process 100 then comprises the steps of: • On the first phase line 12, if there is a difference between the first impedance value and the second impedance value determined: • Below the second predetermined impedance threshold, determine 115 a malfunction of the first RI relay; • Above the third predetermined impedance threshold, determine 116 the proper functioning of the first RI relay; • On the second phase line 14, if there is a difference between the first impedance value and the second impedance value determined: • Below the second predetermined impedance threshold, determine 115' a malfunction of the second relay R2; • Above the third predetermined impedance threshold, determine 116' the proper functioning of the second relay R2.

[0063] Thus, thanks to the method 100 according to the invention it is possible to diagnose, at a lower cost, the operation of the relays RI, R2 allowing to connect to and disconnect from the alternating-direct current converter 8 the electrical power outlets 6, 7 which comprise the vehicle 1.

Claims

1. Demands On-board charger (2) bidirectional for motor vehicle (1), said on-board charger (2) comprising: - A bidirectional AC-DC converter (8), arranged to convert: • A direct current from a high-voltage battery (3) of said vehicle (1) into an alternating current adapted to power a first electrical power outlet (6); • An alternating current from an external power source to said vehicle (1) connected to said first electrical power outlet (6) in a direct current suitable for charging said high-voltage battery (3); - Means for detecting an electrical insulation fault (9) between at least one phase line of the vehicle (1) and an electrical mass (10) of said vehicle (1), these means for detecting an electrical insulation fault (9) being electrically connected to a first phase line (12) and to a first neutral line (13) of said first electrical supply outlet (6); - A first switch (16) arranged on said first phase line (12); - A first switching means (18) arranged to control said first switch (16) between a first closing position (PI) in which the means for detecting an electrical insulation fault (9) are electrically connected to said first electrical supply socket (6) and a second position (P2) in which the first switch (16) is open, said first switch (16) and switching means (18) together forming a first relay (RD; - Said on-board charger (2) being characterized in that it further comprises a first electrically connected resistor (20), when said first switch (16) is in second position (P2), to the first switch (16) and to the electrical ground (10) of the vehicle (1).

2. On-board charger (2) according to the preceding claim, characterized in that: - The AC-DC converter (8) is further arranged to convert a DC current from the high-voltage battery (3) of the vehicle (1) into an AC current suitable for supplying a second power outlet (7) of an electrical device external to said vehicle (1); - The means for detecting an electrical insulation fault (9) are electrically connected to a second phase line (14) and a second neutral line (15) of said second power outlet (7); - The on-board charger (2) further comprises a second switch (17) disposed on said second phase line (14);- A second switching means (19) arranged to drive said second switch (17) between a first closed position (PI) in which the means for detecting an electrical insulation fault (9) are electrically connected to said second power supply socket (7) and a second position (P2) in which said second switch (17) is open, said second switch (17) and switching means (19) together forming a second relay (R2); - A second resistor (21) electrically connected, when said second switch (17) is in second position (P2), to said second switch (17) and to the electrical ground (10) of the vehicle (1).

3. On-board charger (2) according to the preceding claim, characterized in that the first resistor (20) and the second resistor (21) have different impedance values ​​from each other.

4. Electric or hybrid vehicle (1), characterized in that it includes an on-board charger (2) according to any one of the preceding claims.

5. A method (100) for diagnosing the operation of at least one first relay (RI) comprising an on-board charger (2) for a vehicle (1) according to any one of claims 2 to 3, said method (100) comprising the following steps, carried out when the AC-DC converter (8) is inactive, of: - Driving (101), via the first switching means (18), the first switch (16) to bring it into its second position (P2); - Generating (102), via the means for detecting an electrical insulation fault (9), a leakage current on the first phase line (12); - Determining (103), via said means for detecting an electrical insulation fault (9), a first impedance value on said first phase line (12) as a function of said leakage current;- If said first impedance value is less than a first predetermined impedance threshold, control (105), via said first switching means (18), said first switch (16) to bring it to its first position (PD); - Determine (106), via said means for detecting an electrical insulation fault (9), a second impedance value on said first phase line (12) as a function of said leakage current; - If a difference between said first impedance value and said second impedance value is less than a second predetermined impedance threshold, determine (107) a malfunction of said first relay (RI); - If the difference between said first impedance value and said second impedance value is greater than a third predetermined impedance threshold, determine (108) proper operation of said first relay (RI).

6. A method (100) for diagnosing the operation of at least one first relay (IR) according to claim 5, comprising an on-board charger (2) for a vehicle (1) according to any one of claims 2 to 3, characterized in that it comprises the steps of: - To control (101'), via the second switching means (19), the second switch (17) to bring it to its second position (P2); - To generate (102'), via the means for detecting an electrical insulation fault (9), a leakage current on the second phase line (14); - To determine (103'), via said means for detecting an electrical insulation fault (9), a first impedance value on said second phase line (14) as a function of said leakage current; - If said first impedance value is less than the first predetermined impedance threshold, to control (105'), via said second switching means (19), said second switch (17) to bring it to its first position (PD); - To determine (106'), via said means for detecting an electrical insulation fault (9), a second impedance value on said second phase line (14) as a function of said leakage current;- If the difference between said first impedance value and said second impedance value is less than the second predetermined impedance threshold, determine (107') a malfunction of the second relay (R2); - If the difference between said first impedance value and said second impedance value is greater than the third predetermined impedance threshold, determine (108') proper operation of said second relay (R2).

7. A method (100) according to any one of claims 5 or 6, characterized in that: - When the first impedance value of the first phase line (12) is greater than the first predetermined impedance threshold, the method (100) includes a step (104) for determining proper operation of the first relay (RI); - When the first impedance value of the second phase line (14) is greater than said first predetermined impedance threshold, the method (100) includes a step to determine (104') proper functioning of the second relay (R2).

8. A method (100) according to any one of claims 5 to 7, characterized in that it comprises the steps of: - Activating (109), via control means (5) of the on-board charger (2), the bidirectional AC-DC converter (8); - Driving (110), via the first switching means (18), the first switch (16) to bring it to its second position (P2); - Generating (111), via the means for detecting an electrical insulation fault (9), a leakage current on the first phase line (12); - Determining (112), via the means for detecting an electrical insulation fault (9), a first impedance value on the first phase line (12) as a function of said leakage current; - Driving (113), via said first switching means (18), said first switch (16) to the first position (P1);- Determine (114), via the means for detecting an electrical insulation fault (9), a second impedance value on said first phase line (12) as a function of said leakage current; - If the difference between said first impedance value and said second impedance value determined is less than the second predetermined impedance threshold, determine (115) a malfunction of the first relay (RI); - If the difference between said first impedance value and said second impedance value determined is greater than the third predetermined impedance threshold, determine (116) proper operation of said first relay (RI).

9. Method (100) according to any one of claims 6 to 8, characterized in that it comprises the steps of: - Controlling (110'), via the second switching means (19), the second switch (17) to bring it into its second position (P2); Generate (111'), via the means for detecting an electrical insulation fault (9), a leakage current on the second phase line (14); Determine (112'), via the means for detecting an electrical insulation fault (9), a first impedance value on said second phase line (14) as a function of said leakage current; To control (113'), via said second switching means (19), said second switch (17) in the first position (PI); Determine (114'), via the means for detecting an electrical insulation fault (9), a second impedance value on said second phase line (14) as a function of said leakage current; If the difference between said first impedance value and said second impedance value determined is less than the second predetermined impedance threshold, determine (115') a malfunction of the second relay (R2); If a difference between said first impedance value and said second impedance value determined is greater than the second predetermined impedance threshold, determine (116') proper operation of said second relay (R2).

Images