Method for terminating charging of charging system of electric or hybrid vehicle and for diagnosing switching of charging system

Abstract

The invention relates to a method for ending charging of a charging system (32) of an electric vehicle (30) and diagnosing switches (13, 14, 15, 16) of the charging system, the charging system comprising: a step-up stage (5) having a capacitor (6) connected at the input terminals thereof; and two switches (13, 14) each connected to a separate terminal of the charging socket (8), the method comprising a command for opening the switches (13, 14, 15, 16), and if the voltage (VDC) at the terminals of the socket (8) is greater than a safety voltage and the voltages downstream and upstream of the switches (13, 14, 15, 16) are similar, the switches (13, 14, 15, 16) are switched off. When a load has used the step-up stage (5) and in the absence of information about the closing of the charge flip, the method comprises discharging the capacitor (6) and then comparing the voltage (VDC) at the terminals of the socket (8) with the voltage (VB) downstream of the switches (13, 14, 15, 16).

Description

Technical Field

[0001] The present invention relates to the fields of motor vehicles and electrical engineering and, more precisely, to a method for terminating charging and diagnosing a power switch of a charging system of an electric or hybrid vehicle. Background Art

[0002] Electric or hybrid vehicles typically include a high-voltage traction battery that powers the vehicle's electric traction motor with AC power via an inverter. Therefore, the vehicle requires a system for charging the traction battery. Such a system recharges the traction battery by harvesting energy during vehicle braking or by drawing energy from a charging station external to the vehicle. DC charging stations, in particular, allow for very rapid charging of the traction battery by delivering a charging voltage that is greater than the traction battery's voltage, typically on the order of several hundred volts.

[0003] In order to allow such rapid charging, the charging system must include power switches that allow the traction battery to be electrically connected to the DC charging station. The very high currents delivered by such charging stations (which can reach several hundred amperes) can damage these switches. In particular, if these switches are mechanical relays, passing currents of excessive amplitude through them can cause them to fuse to their terminals, making it impossible to turn them off. In the case of MOSFETs (MOSFET is the acronym for Metal Oxide Semiconductor Field Effect Transistor), passing currents of excessive amplitude through them can also damage the substrates of these switches, making it equally impossible to turn them off. In both cases, the power switches are considered to be "fused". In particular, in this patent application, the term "fused" should be understood to mean that if the switch in question is a mechanical relay, the switch remains fused to its terminals, or if the switch in question is a MOSFET, the switch has been damaged to the extent that it cannot be turned off.

[0004] To ensure the electrical safety of the vehicle's users at the start or end of charging, and to prevent subsequent vehicle failures due to such damage to the power switches, the vehicle's computer is typically capable of diagnosing the power switches located between the vehicle's charging socket and the vehicle's traction battery, upstream of the power switches connecting the vehicle's traction battery to the inverter. To perform this diagnostic, the vehicle communicates with the charging station. When the charging station receives an indication that the vehicle has initiated this diagnostic process, it must open its own power switches, i.e., reduce its charging voltage to zero and deliver no charging current to the vehicle.

[0005] Furthermore, some vehicles now include traction batteries whose maximum no-load voltage is much greater than the maximum available voltage level output by conventional charging stations (the maximum voltage delivered by these conventional charging stations is less than 500 V (volts)), and therefore, in such vehicles, the charging socket for DC charging is no longer connected directly to the vehicle's traction battery, but to the input of a boost stage, the output of which is connected to the traction battery.

[0006] In this case, at least some of the power switches that the vehicle must diagnose are located between the vehicle's charging socket and the input of the boost stage, always upstream of the inverter.

[0007] It should be noted that, in this patent application, the terms "upstream" and "downstream" refer to the relative position of an electrical component or assembly with respect to the direction of the electrical current delivered by the station and flowing to the traction battery. Thus, if the electrical current delivered by the station first flows through a first component and then flows through a second component before entering the traction battery, the first component is upstream of the second component.

[0008] Due to the location of these power switches to be diagnosed, when the voltage between the terminals of the charging socket is quite high while the charging socket is still connected to the station, it is difficult for the vehicle computer to distinguish between the following two situations:

[0009] - on the one hand, due to problems caused both by the welding of the power switch of the charging station and by the welding of the power switch connecting the vehicle's traction battery to its inverter, the voltage level of this battery being substantially the same as the voltage level delivered by the charging station,

[0010] - and on the other hand, problems due solely to welding of the power switch to be diagnosed.

[0011] In both cases, it is dangerous for the user of the vehicle to disconnect the charging cable.

[0012] Therefore, there is a need to ensure the safety of users of electric or hybrid vehicles by correctly diagnosing the proper functioning or failure of power switches located downstream of the vehicle's charging receptacle and upstream of the power switches connecting the vehicle's traction battery to the vehicle's inverter, which switches may also be located upstream of the input of the vehicle's boost stage, depending on the configuration of the vehicle's charging system. Summary of the Invention

[0013] The present invention aims to at least partially remedy the shortcomings of the prior art by providing a method for terminating charging of a charging system for an electric vehicle or hybrid vehicle equipped with a boost stage and for diagnosing the power switches of this charging system, the method making it possible, by clever use of the boost stage, to obtain a welding diagnosis for each of these switches used to charge the vehicle's battery via the boost stage, and the method making it possible to improve the electrical safety of the user.

[0014] To this end, the present invention provides a method for terminating charging and diagnosing a power switch of a charging system for an electric vehicle or a hybrid vehicle, the vehicle comprising a traction battery and an inverter capable of supplying power to an electric motor of the vehicle, the charging system comprising at least:

[0015] a switch, called the positive battery switch, connected via a first of its terminals to the positive terminal of the traction battery and via a second of its terminals to the positive input terminal of the inverter, and

[0016] a switch, called the negative battery switch, connected by a first of its terminals to the negative terminal of the traction battery and by a second of its terminals to the negative input terminal of the inverter,

[0017] a boost stage comprising at least one capacitor, a positive terminal of the at least one capacitor being connected to the positive input terminal of the boost stage and a negative terminal of the at least one capacitor being connected to the negative input terminal of the boost stage,

[0018] - two switches, called test switches, used during charging, when the boost stage is used, a first test switch being connected via a first of its terminals to the positive terminal of the charging socket and via a second of its terminals to the positive input terminal of the boost stage, a second test switch being connected via a first of its terminals to the negative terminal of the charging socket and via a second of its terminals to the second terminal of the negative battery switch,

[0019] The method includes:

[0020] - Control the steps of disconnecting the switches to be tested,

[0021] - a first comparison step of comparing the voltage between the terminals of the charging socket on the one hand with a predefined safety voltage on the other hand,

[0022] The method further includes, when the voltage between the terminals of the charging socket is greater than the predefined safety voltage:

[0023] a second comparison step of comparing the voltage between the terminals of the charging socket on the one hand and the voltage between the second terminals of the switches to be tested on the other hand,

[0024] The method is characterized in that, when the charging uses the boost stage, when the difference between the voltages compared in the second comparison step is less than a predefined voltage offset, and in the absence of information about the closure of the vehicle's charging flap for access to the charging socket, the method additionally comprises a step of discharging the capacitor, and then a third comparison step of comparing, on the one hand, the voltage between the terminals of the charging socket and, on the other hand, the voltage between the second terminals of the switches to be tested.

[0025] It should be noted that, unless otherwise stated, the voltages compared in the method according to the present invention are positive voltages or absolute voltage values. Furthermore, the steps of the method are mentioned in the order in which they are performed. These steps are at least partially implemented by the vehicle's computer at the end of DC charging of the traction battery using the vehicle's charging socket, which is connected to a DC charging station via a charging cable.

[0026] It should also be noted that the connections described in this patent application with respect to the terminals of the switches are direct connections, i.e., connections made to components having a purely conductive function and having zero or nearly zero resistance, except potentially when they function as fuses or additional switches that do not form part of the subject matter of the present invention. These switches are power switches, such as mechanical relays or MOSFETs. The first and second terminals of each switch correspond to different terminals of the switch.

[0027] Furthermore, in this patent application, unless otherwise stated, a connection to an input or output of a functional component (such as an inverter or a boost stage) is to be understood as a connection to a terminal of said input or output, i.e., a parallel connection to said input or output, respectively. In this case, the output of the inverter (with respect to its inverter function) is in particular connected to a phase connection point of the electric machine of the vehicle.

[0028] Also in this patent application, the traction battery is understood to be the battery that powers the inverter and electric motor when the vehicle is being driven. In contrast, the vehicle's auxiliary battery powers the vehicle's low-voltage electrical network (e.g., 14V), to which various consumers, including the vehicle's main computer, are connected. Therefore, depending on the electric motor used, the traction battery can also be understood as a propulsion battery. Unless otherwise specified, references to batteries in this patent application are to the vehicle's traction battery. Similarly, in this patent application, in the absence of any indication to the contrary, the terms "electric motor" and "inverter" refer to the electric traction or propulsion motor and to the vehicle's traction or propulsion inverter. Finally, the terms "charging" and "recharging" are considered equivalent in this patent application.

[0029] In the third comparison step of the method according to the invention, charging is performed using a boost stage of the vehicle, the input of which is connected to the charging station and the output of which is connected to the terminals of the traction battery. In the present patent application, "using the boost stage" means that the charging current flows through the boost stage, which is typically the case if the charging system does not have a direct connection between the charging station and the traction battery.

[0030] By discharging the capacitor before the third comparison step, the voltage between the terminals of the charging socket must be different from the voltage between the second terminals of the switches to be tested during the third comparison step (if these switches to be tested are not all welded). In the opposite case, the switches to be tested are diagnosed as being welded, which is impossible in the prior art because the voltage between the terminals of the capacitor is essentially equal to the charging voltage in any case, which makes it impossible to rule out welding of the switches of the charging station.

[0031] The third step is performed if the vehicle's computer does not have information about whether the user will be exposed to dangerous voltages in the vehicle when the charging cable is disconnected (for example, if the vehicle does not have a sensor that detects when the charging flap is closed, or if the sensor is faulty). Therefore, the diagnosis performed after the third comparison step only allows the user to disconnect the charging cable completely safely if at least one of the two switches to be tested is not diagnosed as being welded.

[0032] By means of the invention, a more in-depth diagnostic of the switches used during charging with the boost stage is thus possible, and this allows the user to disconnect the charging cable without risking electric shock.

[0033] In one way of carrying out the invention, the motor and the inverter form part of a boost stage, and the boost stage comprises a switch, called a boost switch, connected via a first of its terminals to the positive terminal of the capacitor and via a second of its terminals to the neutral point of the motor, the method comprises the following steps: when the boost stage is used and when the method does not diagnose any welding of the switches to be tested:

[0034] -Control the boost switch to be disconnected,

[0035] - controlling the inverter to discharge the capacitor,

[0036] - comparing the voltage between the terminals of the capacitor or the phase current of the inverter to a lower threshold value of the capacitor voltage or the phase current, respectively, and detecting welding of the boost switch if the voltage between the terminals of the capacitor is less than the lower threshold value of the capacitor voltage or if the phase current of the inverter is greater than the lower threshold value of the phase current. Conversely, if the voltage between the terminals of the capacitor is greater than the lower threshold value of the capacitor voltage or if the phase current of the inverter is zero for a period of time immediately after a discharge command, the method determines that the boost switch is not welded.

[0037] The electric motor of the charging system is an AC motor, such as a three-phase motor. In this embodiment of the present invention, the stator inductance of the three-phase motor serves as a current storage inductance in the boost stage. This stator inductance is discharged through the inverter into the traction battery during the switching duty cycle of the inverter's switches, which duty cycle is specifically set based on voltage or current measurements taken by the charging system. By reusing components used for vehicle traction to form the boost stage, space in the engine compartment is saved, and the cost of using specialized components to create this stage is reduced.

[0038] Diagnosis of the boost switch makes it possible to ensure correct operation of the vehicle after charging using the boost switch. Specifically, when this switch is welded, the parallel capacitors of the motor and inverter may degrade the operation of the vehicle while driving.

[0039] The charging system comprises in particular:

[0040] a switch, referred to as the positive DC switch, connected via a first of its terminals to the positive terminal of the charging socket and via a second of its terminals to the positive input terminal of the boost stage, and

[0041] a switch, referred to as the negative DC switch, which is connected via a first of its terminals to the negative terminal of the charging socket and via a second of its terminals to the negative input terminal of the boost stage,

[0042] When the charging uses the boost stage, the switches to be tested are the positive DC switch and the negative DC switch, the voltage between the second terminals of the switches to be tested is then called the boost voltage, which also corresponds to the voltage between the terminals of the capacitor.

[0043] In one embodiment of the invention, the charging system comprises a switch, referred to as a bypass switch, connected via a first of its terminals to a first terminal of the positive DC switch and via a second of its terminals to a second terminal of the positive battery switch.

[0044] When the charging does not use the boost stage, the switches to be tested are the negative DC switch and the bypass switch, the voltage between the second terminals of the switches to be tested is then referred to as the inverter voltage.

[0045] In this embodiment of the invention, the charging system comprises means for connecting the charging station directly to the traction battery (i.e. without passing through a step-up stage), i.e. only a few conductors or components with zero or almost zero resistance (such as battery switches) which, when these direct connection means are used, separate the charging socket from the traction battery.

[0046] These direct connection arrangements are advantageously used when the vehicle is connected to a charging station that supplies a charging voltage greater than the maximum no-load voltage of the traction battery. Because the charging current delivered by such a charging station does not pass through the boost stage, it does not experience electrical losses in the boost stage. This also avoids the need to overspecify the vehicle's motor and inverter to allow them to withstand the charging current delivered by such a charging station.

[0047] This embodiment optimizes the number of switches comprising the direct-connect charging system according to the present invention, as the negative DC switch is used both for charging the traction battery with a boost stage and for charging the battery without a boost stage. This embodiment of the direct-connect arrangement does not require the positive DC relay to be closed during charging of the traction battery without a boost stage. Furthermore, this embodiment avoids the need to couple a capacitor at the input of the boost stage with a smoothing capacitor connected to the input of the traction battery, which could adversely affect charging or the charging system during charging of the traction battery without a boost stage.

[0048] The invention thus applies to a charging system that uses a step-up stage to charge at least the traction battery when the charging voltage delivered by the charging station is less than the maximum no-load voltage of the battery, and that may also include means for direct connection to the battery, in which case these direct connection means are used when the charging voltage delivered by the charging station is greater than the maximum no-load voltage of the battery.

[0049] According to an advantageous feature of the method according to the invention, in the case where the charging system comprises means for direct connection to the battery, when closing of the charging flap has been detected, regardless of whether the charging uses the boost stage, the second comparison step is followed by a fourth comparison step of comparing the voltage between the terminals of the charging socket on the one hand with at least one differential voltage threshold value, on the other hand, between a low differential voltage threshold value and an intermediate differential voltage threshold value, with the bypass switch, the positive DC switch and the negative DC switch being controlled to be open and the positive battery switch and the negative battery switch being controlled to be closed, so that welding of the bypass switch and the negative DC switch is detected if the voltage between the terminals of the charging socket is greater than the intermediate differential voltage threshold value, or welding of the positive DC switch and the negative DC switch is detected if the voltage between the terminals of the charging socket is between the low differential voltage threshold value and the intermediate differential voltage threshold value.

[0050] Advantageously, when the fourth comparison step determines that the voltage between the terminals of the charging socket is less than the low differential voltage threshold, a fifth comparison step is performed after the fourth comparison step, in which the common-mode voltage of the positive terminal of the charging socket is compared with at least one common-mode voltage threshold of a low common-mode voltage threshold and an intermediate common-mode voltage threshold on the other hand, thereby concluding that: when the common-mode voltage of the positive terminal of the charging socket is less than the low common-mode voltage threshold, the bypass switch and the positive DC switch have not yet been welded, or if the common-mode voltage of the positive terminal of the charging socket is between the low common-mode voltage threshold and the intermediate common-mode voltage threshold, the positive DC switch has already been welded, or if the common-mode voltage of the positive terminal of the charging socket is greater than the intermediate common-mode voltage threshold, the bypass switch has already been welded.

[0051] Advantageously, if the fourth comparison step determines that the voltage between the terminals of the charging socket is less than the lower differential voltage threshold, a sixth comparison step is performed after the fourth comparison step to compare the common-mode voltage at the negative terminal of the charging socket with a lower common-mode voltage level. This step results in the conclusion that, when the common-mode voltage at the negative terminal of the charging socket is less than the lower common-mode voltage level, the negative DC switch has not yet been welded; otherwise, the negative DC switch has been welded. The fifth and sixth comparison steps are, for example, performed in parallel after the fourth comparison step.

[0052] Various differential or common mode voltage thresholds allow diagnosis of welding of the bypass switch to one of the positive DC switch and the negative DC switch, even though both switches used for charging are not known a priori if the user has disconnected the plug from the outlet.

[0053] In another use case of the method according to the invention, when the charging is not performed using the boost stage, when the difference between the voltages compared in the second comparison step is less than a predefined voltage offset, and in the absence of information about the closure of the vehicle's charging flap for access to the charging socket, the method continues with the following steps:

[0054] - Control the positive battery switch and the negative battery switch to be disconnected,

[0055] - additionally comparing the voltage between the terminals of the charging socket with the predefined safety voltage, and if the voltage between the terminals of the charging socket is less than the predefined safety voltage, performing the following operations:

[0056] - Control the positive battery switch and the negative battery switch to be closed,

[0057] - additionally comparing the voltage between the terminals of the charging socket with the predefined safety voltage, and detecting welding of the negative DC switch and the bypass switch if the voltage between the terminals of the charging socket is greater than the predefined safety voltage, otherwise concluding that at least one of the bypass switch and the negative DC switch is not welded.

[0058] Therefore, in this use case, the method according to the invention cleverly uses the voltage difference measured according to the status of the positive battery switch and the negative battery switch to perform a diagnosis of the negative DC switch and the bypass switch.

[0059] In the other use case of the method according to the invention, during the additional comparison of the voltage between the terminals of the charging socket with the predefined safety voltage, when the voltage between the terminals of the charging socket is greater than the predefined safety voltage, the method continues with the following steps:

[0060] - comparing the inverter voltage with the predefined safety voltage, thereby concluding that: when the inverter voltage is less than the predefined safety voltage, at least one of the bypass switch and the negative DC switch is not welded, otherwise the charging cable connected to the charging socket is prevented from being disconnected, and the step loops back to the additional comparison step.

[0061] Therefore, the present invention minimizes situations in which the user is not allowed to disconnect the charging plug from the socket.

[0062] Returning to the more general use case of the present invention, according to another advantageous feature of the method according to the present invention, when the third comparison step determines that the voltage between the terminals of the charging socket is equal to the boost voltage, the method detects that the positive DC switch and the negative DC switch are welded; otherwise, the method determines that at least one of the positive DC switch and the negative DC switch is not welded. Of course, given the levels of the compared voltages, in the present patent application, the equality between the voltages is assessed to be within a tolerance of a few volts.

[0063] In addition, advantageously, in the method according to the present invention, when the charging uses the boost stage, and when the first comparison step determines that the voltage between the terminals of the charging socket is less than the predefined safety voltage, or when the second comparison step determines that the difference between the boost voltage and the voltage between the terminals of the charging socket is greater than the predefined voltage offset, the method determines that at least one of the positive DC switch and the negative DC switch is not welded.

[0064] Similarly, when the charging does not use the boost stage, and when the first comparison step determines that the voltage between the terminals of the charging socket is less than the predefined safety voltage, or when the second comparison step determines that the difference between the voltage of the inverter and the voltage between the terminals of the charging socket is greater than the predefined voltage offset, the method determines that at least one of the bypass switch and the negative DC switch is not welded.

[0065] Advantageously, when the method according to the present invention determines that at least one of the positive DC switch and the negative DC switch is not welded when the boost stage is used for charging, or determines that at least one of the bypass switch and the negative DC switch is not welded when the boost stage is not used for charging, the method proceeds with a seventh comparison step of comparing the common-mode voltage at the negative terminal of the charging socket with a first lower common-mode voltage limit, respectively, while the negative DC switch and the positive DC switch or the bypass switch are controlled to be open, thereby concluding that the negative DC switch is not welded when the common-mode voltage at the negative terminal of the charging socket is less than the first lower common-mode voltage limit, and proceeds with an eighth comparison step of comparing the common-mode voltage at the positive terminal of the charging socket with a second lower common-mode voltage limit, respectively, thereby concluding that the positive DC switch or the bypass switch is not welded when the common-mode voltage at the positive terminal of the charging socket is less than the second lower common-mode voltage limit.

[0066] The seventh comparison step and the eighth comparison step are performed in parallel, for example.

[0067] Advantageously, during the seventh comparison step, when the common-mode voltage at the negative terminal of the charging socket is greater than the first low voltage limit, the method according to the invention proceeds with a ninth comparison step of comparing the boost voltage or the inverter voltage, respectively, on the one hand, with the voltage between the terminals of the charging socket, on the other hand, after the positive DC switch or the bypass switch, respectively, has been controlled to be closed, so that if the boost voltage or the inverter voltage, respectively, is equal to the voltage between the terminals of the charging socket, then the welding of the negative DC switch is detected, otherwise it is concluded that the negative DC switch has not been welded.

[0068] Advantageously, during the eighth comparison step, when the common-mode voltage at the positive terminal of the charging socket is greater than the second low voltage limit, the method proceeds, after the negative DC switch has been controlled to be closed, with a tenth comparison step of comparing the boost voltage or the inverter voltage, respectively, on the one hand, with the voltage between the terminals of the charging socket, on the other hand, so that if the boost voltage or the inverter voltage, respectively, is equal to the voltage between the terminals of the charging socket, then the welding of the positive DC switch or the bypass switch, respectively, is detected, otherwise it is concluded that the positive DC switch or the bypass switch, respectively, has not been welded. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Other characteristics and advantages of the invention will become more apparent from the following description on the one hand and from a number of non-limiting examples of embodiments given by way of indication with reference to the accompanying drawings on the other hand, in which:

[0070] [ Figure 1 ] schematically shows an electric vehicle or hybrid vehicle connected to a charging station and comprising a charging system in one embodiment of the invention, the vehicle implementing a method according to the invention for terminating charging of a charging system of the vehicle and diagnosing a power switch of the charging system,

[0071] [ Figure 2 ] shows that Figure 1 The first step of the charging termination and diagnostic method according to the present invention is implemented in the case of a vehicle that has just finished charging using the boost level of the vehicle's charging system,

[0072] [ Figure 3 ] shows that when Figure 2 When the first steps of the charge termination and diagnosis method do not diagnose any welding of the switch between the charging station and the boost stage, the steps following these first steps,

[0073] [ Figure 4 ] shows that when voltage is still present between the terminals of the charging socket and the computer of the vehicle implementing the method according to the invention has been instructed to close the charging flap (thus preventing access to the charging socket), Figure 2 The steps following the first step of the charge termination and diagnostic method,

[0074] [ Figure 5 ] shows that Figure 1 The first step of the charge termination and diagnostic method according to the present invention is implemented in the case of a vehicle that has just finished charging without using the boost level of the vehicle's charging system,

[0075] [ Figure 6 ] shows that when voltage is still present between the terminals of the charging socket and the computer of the vehicle implementing the method according to the invention has no information about a potential closing of the charging flap Figure 5 The steps following the first step of the charge termination and diagnostic method, and

[0076] [ Figure 7 ] shows that when the method according to the invention determines that at least one of the switches used during charging and upstream of the boost stage or allowing the charging socket to be connected directly to the traction battery is not welded Figure 2 、 Figure 5 or Figure 6 The steps following the steps of the charge termination and diagnosis method. DETAILED DESCRIPTION

[0077] According to one embodiment of the present invention, Figure 1 The illustrated electric or hybrid vehicle 30 comprises a charging system 32. The vehicle 30 comprises a traction battery 2 and the charging system 32 allows the traction battery 2 to be recharged with energy supplied by a DC charging station 60 to which the vehicle 30 is connected via a charging cable 70. At the end of DC charging, the vehicle implements the method 1 according to the invention for terminating charging of the charging system 32 and diagnosing the power switch of the charging system, as Figures 2 to 7 shown.

[0078] Now refer to Figure 1 The charging system 32 is described with reference to the power switches 10 and 11 along with other elements of the vehicle 30 in order to clearly illustrate how the power switches are used during charging of the traction battery 2 .

[0079] The vehicle comprises a traction inverter 3 and a three-phase electric motor 4 connected to the vehicle wheels via a drive train. The inverter 3 and the electric motor 4 are powered by a traction battery 2 in order to move the vehicle.

[0080] To this end, the vehicle includes a first switch 11 and a second switch 12 for connecting the traction battery 2 to the inverter 3. The first switch, referred to as the positive battery switch, is connected to the positive terminal of the traction battery 2 via a first terminal and to the positive input terminal of the inverter 3 via a second terminal. The second switch, referred to as the negative battery switch, is connected to the negative terminal of the traction battery 2 via a first terminal and to the negative input terminal of the inverter 3 via a second terminal. The input of the inverter herein refers to the portion of the inverter that receives DC current and delivers rectified current. The term "input" should be understood relative to the inverter's functionality. Similarly, in this patent application, the terms "input" and "output" should be understood relative to the functionality of the referenced electrical components or parts. A smoothing capacitor 7 is connected to the input of the inverter. This capacitor smoothes the current entering the battery 2 when the inverter 3 functions as a rectifier of the current output by the electric machine 4 operating in generator mode.

[0081] The positive and negative battery switches 11, 12 thus form the connection means between the traction battery 2 and the input of the inverter 3. Furthermore, the output of the inverter 3 is directly connected to the electric machine 4, ie without an intermediate switch.

[0082] The vehicle also includes a charging socket 8 that is connected to a DC charging station 60 via a charging cable 70. For example, this charging socket 8 is a CHAdeMO connector compliant with IEC 61851-23, -24. Alternatively, the vehicle includes only one charging socket (e.g., a combined DC charging socket compliant with IEC 62196-3) that allows connection to both a DC charging station and an AC charging station. In this case, the vehicle 30 also includes an AC charging device. In yet another alternative, the vehicle has only one charging socket, which is intended to be connected only to a DC charging station.

[0083] The charging system 32 comprises a boost stage 5 comprising an inverter 3, an electric machine 4 and a capacitor 6 connected to the input of the boost stage 5. More precisely, the positive terminal of the capacitor 6 is connected to the neutral point of the electric machine 4 via a switch 16 (called a boost switch), and the negative terminal of the capacitor 6 is connected to the negative input terminal of the inverter 3. This boost stage 5 is used by the vehicle during charging of the traction battery 2 using a charging voltage supplied by a charging station, which is less than the maximum no-load voltage of the traction battery 2.

[0084] To this end, the charging system 32 comprises a control device 40 for the inverter 3 and the electric machine 4, which is capable of converting the charging voltage input into the boost stage 5 into a voltage output from the boost stage 5 that is greater than the voltage of the traction battery 2. The stator inductances of the electric machine 4 then serve as current storage inductances in the boost stage 5, and these stator inductances are discharged into the traction battery 2 through the inverter 3 during the switching duty cycle of the switches of the inverter 3, which duty cycle is set by the control device 40, which also measures the voltage V between the terminals of the capacitor 6. B In addition to measuring the voltage V B In addition to the device, the charging system 32 also includes a device for measuring at least one phase current I flowing through the inverter 3 B device.

[0085] A switch 16, referred to as a boost switch, is connected via a first of its terminals to the positive terminal of the boost capacitor 6 and via a second of its terminals to the neutral point of the electric machine 4. The boost switch 16 allows the boost capacitor 6 at the input of the boost stage 5 to be disconnected outside of the phases in which the traction battery 2 is being charged by an external charging station. The boost switch 16 is in particular kept open while the vehicle is being driven. Thus, capacitive coupling of the boost capacitor 6 with the electric machine 4 is avoided while the vehicle is being driven.

[0086] For example, the control device 40 of the inverter 3 is a microcontroller that controls the switches of the inverter 3 both in the traction mode and in the mode of charging the vehicle using the boost stage 5 .

[0087] The charging system 32 further comprises means for connecting the charging socket 8 to the input of the voltage step-up stage 5 , these means comprising:

[0088] a switch 13 , referred to as the positive DC switch, which is connected via a first of its terminals to the positive terminal of the charging socket 8 and via a second of its terminals to the boost switch 16 , and

[0089] A switch 14 , referred to as the negative DC switch, is connected via a first of its terminals to the negative terminal of the charging socket 8 and via a second of its terminals to the negative input terminal of the inverter 3 .

[0090] These switches 13 , 14 are used to recharge the traction battery 2 via the step-up stage 5 when the charging voltage of the charging station connected to the charging socket 8 is less than the maximum no-load voltage of the battery 2 .

[0091] Finally, the charging system 32 also includes means for connecting the charging socket 8 directly to the traction battery 2, these means being used to recharge the battery when the charging voltage of the charging station connected to the charging socket 8 is greater than the maximum no-load voltage of the battery 2. These connection means include a negative DC switch 14 and a switch 15, referred to as a bypass switch, which is connected via a first of its terminals to a first terminal of the positive DC switch 13 and via a second of its terminals to a second terminal of the positive battery switch 11.

[0092] Switches 11, 12, 13, 14, and 15 are grouped together in a connection box 9 of the charging system 32. The connection box 9 also includes a pre-charge relay 10, which is connected to the positive terminal of the traction battery 2 via one of its terminals and to the positive terminal of the inverter 3 via the other of its terminals. A pre-charge resistor is connected between the pre-charge relay 10 and the positive terminal of the battery 2. Before any charging of the battery 2 occurs, the pre-charge relay 10 is first closed to charge the smoothing capacitor 7, then the pre-charge relay 10 is opened and the positive battery switch 11 is closed. The pre-charge relay 10 and the pre-charge resistor form a pre-charging device. It should be noted that other types of pre-charging devices can be used instead of this relay and resistor system.

[0093] The charging system 32 also includes one or more software and / or hardware modules of a main computer 50 of the vehicle. In particular, the main computer 50 includes means for communicating with the charging station 60 and the control means of the power switches 10, 11, 12, 13, 14, 15 and 16, these communication means and control means forming part of the charging system 32. The control means of the power switches 10, 11, 12 are also present in the system 20 for managing the traction battery 2, with which the main computer 50 communicates, and the management system 20 potentially forming an integral part of the charging system 32.

[0094] The system 20 for managing the traction battery 2 is coupled to the current entering the battery and the voltage V between the terminals of the charging socket 8 DC The sensor 22 allows the system to monitor the charging of the battery 2. The voltage V between the terminals of the charging socket 8 DCis the differential voltage between the two terminals of the charging socket 8. The system 20 for managing the battery 2 also includes a bypass switch 15 and control devices for the positive and negative DC switches 13 and 14. Therefore, if the system 20 for managing the battery 2 detects a fault during charging, it can interrupt charging for safety reasons without requiring intervention from the vehicle's main computer 50. Therefore, switches 10, 11, 12, 13, 14, and 15 can each be controlled by the vehicle's management system 20 and main computer 50, thereby achieving safety-related redundancy. Similarly, the boost switch 16 can be controlled by the main computer 50 and the control device 40.

[0095] In addition to sensor 22 , charging system 32 includes means for measuring a common mode voltage V+ between the positive terminal of charging receptacle 8 and ground of vehicle 30 , and means for measuring a common mode voltage V− between the negative terminal of charging receptacle 8 and ground of vehicle 30 .

[0096] The vehicle's main computer 50 uses devices or components of the charging system 32 to implement the method 1 for terminating charging and diagnosing at least some of the power switches 13 , 14 , 15 , 16 .

[0097] Now refer to Figure 2 An embodiment of the method 1 according to the invention is described when the traction battery 2 has just been recharged via the charging station 60 using the boost stage 5 . In this use case of the invention, the charging station 60 cannot supply a voltage greater than 400 V, for example, while the traction battery 2 has a maximum no-load voltage of 800 V. Therefore, the charging current that has just ended flows specifically through the positive and negative DC switches 13 , 14 , the boost switch 16 , and the positive and negative battery switches 11 , 12 , but without using the bypass switch 15 , which remains open during charging.

[0098] Method 1 begins with a first step 100 in which the method completes a message exchange with the charging station 60, which allows the method to ensure that its request to open the switches 62, 64 of the charging station 60 has been received and accepted during the implementation of a charge termination protocol that allows the implementation of diagnostics on the power switches of the vehicle 30. Therefore, during the first step 100, the voltage delivered by the charging station 60 is theoretically zero (unless there is a fault in the charging station 60).

[0099] It should be noted that the positive and negative battery switches 11 , 12 and the boost switch 16 are closed during this first step 100 .

[0100] The next step 110 is to control the positive and negative DC switches 13 and 14 to be turned off.

[0101] After a few milliseconds, the method 1 implements the next step 120 , which is to convert the voltage V between the terminals of the charging socket 8 to DC A first comparison step is performed with, on the other hand, a predefined safety voltage S1 , here set equal to 60 V. Of course, as a variant, another predefined safety voltage value may be chosen, in particular according to current standards relating to electrical safety.

[0102] When, in a first comparison step 120 , the method 1 determines the voltage V between the terminals of the charging socket 8 DC When the voltage is less than the predefined safety voltage S1 (branch is), the method 1 determines that at least one of the positive DC switch 13 and the negative DC switch 14 is not welded, and the method 1 proceeds to step 470 (cross reference A). Figure 7 It should be noted that in this patent application, the comparison step uses strict or weak inequality conditions without changing the nature of the present invention. Therefore, the strict or weak nature of the inequality is not specified in this embodiment of the present invention.

[0103] In contrast, when, in a first comparison step 120 , method 1 determines the voltage V between the terminals of the charging socket 8 , DC If the voltage V between the terminals of the charging socket 8 is greater than the predefined safety voltage S1 (branch No), then after the first comparison step 120, the voltage V between the terminals of the charging socket 8 is compared. DC and on the other hand the voltage V between the terminals of the capacitor 6 measured by the charging system 32 B A second comparison step 130 is performed in which the voltages of the boost voltages are compared.

[0104] When, in a second comparison step 130 , the method 1 determines the voltage V between the terminals of the charging socket 8 DC With the boost voltage V B When the difference between the positive DC switch 13 and the negative DC switch 14 in absolute value is greater than the predefined voltage offset S2 (equal to 30V in this embodiment of the present invention), the method 1 determines that at least one of the positive DC switch 13 and the negative DC switch 14 is not welded, and the method 1 proceeds to step 470, which is Figure 7 Of course, another value may be selected for the predefined voltage offset S2, in particular depending on the use case of the charging system 32.

[0105] When, in a second comparison step 130 , the method 1 determines the voltage V between the terminals of the charging socket 8 DC With the boost voltage V BWhen the difference between the positive and negative battery switches 11 and 12 in absolute value is less than the predefined voltage offset S2 (branch No), then if the sensor allowing the closing of the charging flap close to the charging socket 8 is active (branch Yes of condition 135), the next step is step 170 of controlling the positive battery switch 11 and the negative battery switch 12 to be opened, and then the charging cable 70 is allowed to be disconnected if one of the following conditions is met:

[0106] - Voltage V between the terminals of the charging socket 8 DC , the common mode voltage V+ between the positive terminal of the charging socket 8 and the ground of the vehicle 30 and the common mode voltage V− between the negative terminal of the charging socket 8 and the ground of the vehicle 30 are less than the predefined safety voltage S1, or

[0107] - Voltage V between the terminals of inverter 3 O Less than the predefined safety voltage S1,

[0108] And if one of these conditions is met, the computer waits for an instruction to close the flip cover and then proceeds (cross reference B) to step 240, which is Figure 4 is shown in and described below.

[0109] When, in a second comparison step 130 , the method 1 determines the voltage V between the terminals of the charging socket 8 DC With the boost voltage V B When the difference between the two, expressed in absolute value, is less than the predefined voltage offset S2, and when the vehicle's computer 50 has no information about a potential disconnection of the charging cable 70 (branch No of condition 135), for example because the vehicle 30 is not equipped with a charging flap closed sensor or this sensor is faulty, the next step is a step 140 of discharging the capacitor 6 at the input of the boost stage 5, so that the boost voltage V B A predefined voltage is reached, for example 100 V. For this purpose, the computer 5 uses the control means 40 of the inverter 3 .

[0110] After a waiting time of a few milliseconds, a discharge step 140 is followed by a voltage V between the terminals of the charging socket 8 . DC On the other hand, the boost voltage V B A third comparison step 150 is performed in which a comparison is made.

[0111] When, in the third comparison step 150 , the method 1 determines the voltage V between the terminals of the charging socket 8 DC Equal to the boost voltage V B(Branch Yes), then method 1 detects 160 the welding of the positive DC switch 13 and the welding of the negative DC switch 14, otherwise (Branch No) method 1 determines that at least one of the positive DC switch 13 and the negative DC switch 14 is not welded. In the latter case, method 1 proceeds to step 470, which is Figure 7 is shown in and described below.

[0112] It should be noted that in the case where both the negative and positive DC switches 14 and 13 are diagnosed as being welded, disconnection is permitted after the positive and negative battery switches 11 and 12 have been disconnected and it has been verified that they are not welded.

[0113] It will now be assumed that, at the end of the method 1 according to the invention, the computer 50 has concluded that the positive and negative DC switches 13, 14 have not yet been welded, i.e., they are not blocked in the closed position. This conclusion can be drawn, for example, because, at the end of the first comparison step 120, the voltage between the terminals of the charging socket 8 is less than the predefined safety voltage S1, and because the method then determines (hereinafter with reference to Figure 7 The common mode voltage of each of the terminals of the charging socket 8 described in steps 490 and 545) is also less than the predefined safety voltage S1.

[0114] Then, method 1 is implemented Figure 2 The steps are intended to determine the diagnosis of the boost switch 16.

[0115] The first step of the new diagnosis is to control the boost switch 16 to open 180. This first step of controlling the opening 180 is followed by a step 190 of controlling the inverter 3 to discharge the capacitor 6, which is then followed by a step of lowering the boost voltage V B The voltage of the capacitor 6 is lowered to a lower threshold value S3 (eg 60V) or the phase current I in the inverter 3 is B With the phase current I B Step 215 compares the amps to a low threshold value S4 of several amps (eg, 5 amps).

[0116] If method 1 determines 220 the boost voltage V in comparison step 215 B After a few seconds, the voltage of the capacitor 6 is less than the low threshold S3, or the phase current I in the inverter 3 is less than the low threshold S3. B Greater than the phase current I for more than a few milliseconds B If the low threshold S4 is reached, this is because the capacitor 6 may have discharged, and therefore the method 1 determines in step 230 that the boost switch 16 is welded.

[0117] In contrast, if method 1 determines in comparison step 215 that the boost voltage V BAfter a few seconds, it is still greater than the low threshold S3 of the voltage of the capacitor 6 or the phase current I in the inverter 3 B If φ remains close to zero for several milliseconds, this is because it is unlikely that capacitor 6 is over-discharged, and therefore method 1 determines in step 210 that boost switch 16 is not welded.

[0118] Figure 3 The steps following the step of controlling the positive and negative battery switches 11, 12 to be opened 170 and the computer 50 receiving the indication that the charging flap is closed are shown. DC When the boost voltage V B The voltage between the terminals of the charging socket is V DC This closure occurs when the difference between the positive and negative DC switches 13 and 14 is less than a predefined voltage offset S2. Therefore, a complete diagnosis of the positive and negative DC switches 13 and 14 cannot be performed. It should be noted that the indication that the charging flap is closed may be derived by the computer 50 based on the vehicle 30 being driven above a certain speed threshold (e.g., at more than 5 km / h).

[0119] In this configuration, the first step of diagnosis with the flip lid closed is to control the positive DC switch, negative DC switch, and bypass switches 13, 14, and 15 to open 240 if they are not already open, and to control the positive and negative battery switches 11 and 12 to close if they are not already closed. The latter situation may occur, for example, between the second comparison step 130 and the discharge step 140 if the computer 50 detects that the vehicle is being driven between these two steps.

[0120] It should be noted that in this configuration, the computer 50 also does not know whether the charging that just ended was charging using the boost stage 5 or charging without using the boost stage 5; in other words, the computer 50 does not know whether it must diagnose the positive and negative DC switches 13 and 14, or the bypass switch 15 and the negative DC switch 14, respectively. Specifically, in this embodiment of the present invention, the type of charging that has just been performed is not stored in the memory in the computer 50.

[0121] After the control step 240, the voltage V between the terminals of the charging socket 8 is set to DC A fourth comparison step 250 is performed with a lower differential voltage threshold S5 on the other hand, which is set to 60V, for example.

[0122] In the fourth comparison step 250 , if the method 1 determines that the voltage V between the terminals of the charging socket 8 DCIf the voltage V between the terminals of the charging socket 8 is greater than the low differential voltage threshold S5, then this is because the two switches connected to the charging socket are welded. In this case, the next step is to set the voltage V between the terminals of the charging socket 8 to DC is compared with the intermediate differential voltage threshold S6, which is set to 500 V here. If the method 1 determines 260 the voltage V between the terminals of the charging socket 8 DC is less than the middle differential voltage threshold S6 and greater than the low differential voltage threshold S5, this is because the charging that has just ended used the boost stage 5 and method 1 determines 270 that the positive and negative DC switches 13, 14 are welded. In contrast, if the method determines 280 that the voltage V between the terminals of the charging socket 8 is DC Between the middle differential voltage threshold S6 and the high differential voltage threshold S7 corresponding to 900V, for example, this is because the charging that has just ended did not use the boost stage 5 and method 1 determines 290 that the bypass switch 15 and the negative DC switch 14 are welded.

[0123] In the fourth comparison step 250 , if the method 1 determines that the voltage V between the terminals of the charging socket 8 DC If the voltage is less than the low differential voltage threshold S5, this is because at least one of the two switches connected to the charging socket is welded.

[0124] In this case, after the fourth comparison step 250, a fifth comparison step 300 is performed, in which the common-mode voltage V+ of the positive terminal of the charging socket 8 is compared on the one hand with a low common-mode voltage threshold S8, which is set to 60V, for example. If the common-mode voltage V+ of the positive terminal of the charging socket 8 is less than (branch YES) the low common-mode voltage threshold S8, then the method 1 determines 310 that neither the bypass switch 15 nor the positive DC switch is welded. In contrast, if the method 1 determines that the common-mode voltage V+ of the positive terminal of the charging socket 8 is greater than (branch NO) the low common-mode voltage threshold S8, then the next step is to compare the common-mode voltage V+ of the positive terminal of the charging socket 8 with an intermediate common-mode voltage threshold S9, which is set to 500V, for example. If the method 1 determines 320 that the voltage V+ between the terminals of the charging socket 8 is greater than DC is less than the middle common mode voltage threshold S9 and greater than the low common mode voltage threshold S8, this is because the charging that has just ended used the boost stage 5 and method 1 determines 330 that the positive and negative DC switches 13, 14 are welded. In contrast, if the method determines 340 that the voltage V between the terminals of the charging socket 8 is DC Between the middle common mode voltage threshold S9 and the high common mode voltage threshold S10 corresponding to 900 V, for example, this is because the charging that has just ended did not use the boost stage 5 and method 1 determines 350 that the bypass switch 15 and the negative DC switch 14 are welded.

[0125] In addition, when the method 1 determines at the end of the fourth comparison step 250 that at least one of the two switches connected to the charging socket is welded (the voltage V between the terminals of the charging socket 8 is DC If the common-mode voltage V- at the negative terminal of the charging socket 8 is less than the low differential voltage threshold S5 (the voltage V- is less than the low differential voltage threshold S5), then, after the fourth comparison step 250, a sixth comparison step 360 is performed to compare the common-mode voltage V- at the negative terminal of the charging socket 8 with a low common-mode voltage level S11, for example, set to 60V. If the common-mode voltage V- at the negative terminal of the charging socket 8 is less than the low common-mode voltage level S11 (branch YES), then method 1 determines 370 that the negative DC switch 14 is not welded. In contrast, if the common-mode voltage V- at the negative terminal of the charging socket 8 is greater than the low common-mode voltage level S11 (branch NO), then method 1 determines 380 that the negative DC switch 14 is welded.

[0126] Now refer to Figure 5 An embodiment of method 1 according to the present invention will be described when the traction battery 2 has just been recharged via a charging station 60 without using a boost stage 5. In this use case of the present invention, the charging station 60 is capable of supplying a voltage greater than or equal to the maximum no-load voltage of the traction battery 2 (800 V). Consequently, the charging current that has just concluded flows specifically through the negative DC and bypass switches 14 and 15, as well as the positive and negative battery switches 11 and 12, without using the boost switch 16, which remains open during charging. In this use case, the first step of method 1 is essentially the same as the first step in the case of charging using a boost stage 5, and will therefore be referenced in the same manner, while also noting the differences regarding the switches in question and certain comparison voltages.

[0127] The method 1 starts with a first step 100 which is identical to the first step of the case of charging using the boost stage 5. In particular, during this first step 100, the positive and negative battery switches 11, 12 are closed.

[0128] The next step 110 is to control the negative DC switch and the bypass switches 14 and 15 to be turned off.

[0129] After a few milliseconds, the method implements the next step 120 , which is to convert the voltage V between the terminals of the charging socket 8 . DC A first comparison step with a predefined safety voltage S1 on the other hand.

[0130] When, in a first comparison step 120 , the method 1 determines the voltage V between the terminals of the charging socket 8 DCWhen the voltage is less than the predefined safety voltage S1 (branch is), the method 1 determines that at least one of the bypass switch 15 and the negative DC switch 14 is not welded, and the method 1 proceeds to step 470, which is Figure 7 is shown in and described below.

[0131] In contrast, when, in a first comparison step 120 , method 1 determines the voltage V between the terminals of the charging socket 8 , DC If the voltage V between the terminals of the charging socket 8 is greater than the predefined safety voltage S1 (branch No), then after the first comparison step 120, the voltage V between the terminals of the charging socket 8 is compared. DC On the other hand, the voltage V between the terminals of the inverter 3 is measured by the charging system 32 O A second comparison step 130 is performed in which the voltages (referred to as inverter voltages) are compared.

[0132] When, in a second comparison step 130 , the method 1 determines the voltage V between the terminals of the charging socket 8 DC and the inverter voltage V O When the difference between the bypass switch 15 and the negative DC switch 14 in absolute value is greater than the predefined voltage offset S2, the method 1 determines that at least one of the bypass switch 15 and the negative DC switch 14 is not welded, and the method 1 proceeds to step 470, which is Figure 7 is shown in and described below.

[0133] When, in a second comparison step 130 , the method 1 determines the voltage V between the terminals of the charging socket 8 DC and the inverter voltage V O When the difference between the positive and negative battery switches 11 and 12 in absolute value is less than the predefined voltage offset S2 (branch No), if the sensor indicating that the charging flip cover is closed is active (branch Yes of condition 135), the next step is step 170 of controlling the positive battery switch 11 and the negative battery switch 12 to be disconnected, and then the charging cable is allowed to be disconnected if one of the following conditions is met:

[0134] - Voltage V between the terminals of the charging socket 8 DC , the common mode voltage V+ between the positive terminal of the charging socket 8 and the ground of the vehicle 30 and the common mode voltage V− between the negative terminal of the charging socket 8 and the ground of the vehicle 30 are less than the predefined safety voltage S1, or

[0135] -Inverter voltage V O Less than the predefined safety voltage S1,

[0136] And if one of these conditions is met, the computer 50 waits to receive an indication that the lid is closed and then proceeds to step 240, which is Figure 4As shown in FIG, step 240 and subsequent steps are the same as the case where the boost stage 5 is used for charging.

[0137] When, in a second comparison step 130 , the method 1 determines the voltage V between the terminals of the charging socket 8 DC and the inverter voltage V O When the difference between the charging cable and the charging cable, expressed in absolute value, is less than the predefined voltage offset S2, and when the vehicle's computer 50 has no information about a potential disconnection of the charging cable (branch No of condition 135), for example because the vehicle is not equipped with a charging flap closed sensor or the sensor is faulty, then method 1 continues (cross reference C). Figure 6 The steps shown are:

[0138] - Control the positive battery switch and the negative battery switch 13, 14 to disconnect 390, and then after a few seconds,

[0139] - Set the voltage V between the terminals of the charging socket 8 DC An additional comparison 400 is performed with a predefined safety voltage S1 and if the voltage V between the terminals of the charging socket 8 DC If the voltage is less than the predefined safety voltage S1, the following operations are performed:

[0140] - Control the positive battery switch and the negative battery switch 13, 14 to close 410, then

[0141] - Set the voltage V between the terminals of the charging socket 8 DC An additional comparison 420 is performed with the predefined safety voltage S1 and if method 1 determines that the voltage V between the terminals of the charging socket 8 DC If the voltage is greater than the predefined safety voltage S1 (branch No), method 1 detects 430 the welding of the negative DC switch 14 and the welding of the bypass switch 15. In this case, after the positive and negative battery switches 11 and 12 have been disconnected and it has been verified that the positive and negative battery switches are not welded, disconnection is allowed.

[0142] In contrast, if in the additional comparison step 420 , the method 1 determines the voltage V between the terminals of the charging socket 8 DC When the voltage is less than the predefined safety voltage S1 (branch is), the method 1 determines that at least one of the bypass switch 15 and the negative DC switch 14 is not welded, and the method 1 proceeds to step 470, which is Figure 7 is shown in and described below.

[0143] When the voltage V between the terminals of the charging socket 8 during the additional comparison 400 DCIf it is greater than the predefined safety voltage S1 (branch No), then the inverter voltage V O Step 440 of comparing with the predefined safety voltage S1. If the inverter voltage V O If the voltage is less than the predefined safety voltage S1, the user can disconnect the charging cable 70, the method 1 determines 450 that at least one of the bypass switch 15 and the negative DC switch 14 is not welded, and the method 1 proceeds to step 470, which is Figure 7 In contrast, if the inverter voltage V O If the voltage is greater than the predefined safety voltage S1 (branch No), method 1 prevents 460 the user from disconnecting charging cable 70 and loops back to the additional comparison step 400. Specifically, in this case, a dangerous voltage persists between the terminals of charging receptacle 8 and between the terminals of the inverter, which may be the result of simultaneous welding of switches 62, 64 and the negative DC switch and bypass switches 14, 15 of charging station 60, or switches 62, 64 and the positive and negative battery switches 11, 12 of charging station 60, or even the negative DC switch and bypass switches 14, 15 and the positive and negative battery switches 11, 12. The user must then press an emergency button on charging station 60 to reduce the voltage delivered by the charging station and allow charging receptacle 8 to be disconnected.

[0144] Finally, when Method 1 is mentioned above about Figure 2 、 Figure 5 or Figure 6 In one of the aforementioned cases, when it is determined that at least one of the bypass switch 15 and the negative DC switch 14 is not welded when charging without using the boost stage 5, or when it is determined that at least one of the negative DC switch and the positive DC switches 14, 13 is not welded when charging without using the boost stage 5, the following operations are performed:

[0145] - Allows the user to disconnect the charging cable, and

[0146] - Method 1 continues Figure 7 The step of controlling the bypass switch 15 and the switches that have not been controlled to be opened among the positive DC switch and the negative DC switch 13 and 14 to be opened is performed 470.

[0147] During this controlled opening step 470 , the positive and negative battery switches 11 , 12 remain closed.

[0148] The step 470 of control disconnection is then followed by two comparison steps carried out in parallel or one after the other, these steps being:

[0149] a seventh comparison step 480 of comparing the common mode voltage V− of the negative terminal of the charging socket 8 on the one hand with the first low common mode voltage limit S12 (eg 60 V) on the other hand, and

[0150] An eighth comparison step 540 of comparing the common mode voltage V+ of the positive terminal of the charging socket 8 on the one hand with the second low common mode voltage limit S13 (eg 60 V) on the other hand.

[0151] When, in the seventh comparison step 480, method 1 determines that the common-mode voltage V− at the negative terminal of charging receptacle 8 is less than (branched at) the first lower common-mode voltage limit S12, method 1 determines 490 that the negative DC switch is not welded. Similarly, when, in the eighth comparison step 540, method 1 determines that the common-mode voltage V+ at the positive terminal of charging receptacle 8 is less than (branched at) the second lower common-mode voltage limit S13, method 1 determines 545 that the positive DC switch 13 is not welded (when charging uses boost stage 5) or the bypass switch 15 is not welded (when charging does not use boost stage 5).

[0152] In contrast, when, in the seventh comparison step 480, method 1 determines that the common-mode voltage V- at the negative terminal of the charging socket 8 is greater than (branch No) the first lower common-mode voltage limit S12, the seventh comparison step 480 is followed by a step 500 of controlling the positive DC switch (if the boost stage 5 is used for charging) or the bypass switch 15 (if the boost stage 5 is not used for charging) to be closed.

[0153] After a few milliseconds, the control closing step 500 is followed by a ninth comparison step 510 in which, when charging uses the boost stage, the method 1 compares the boost voltage V B On the other hand, the voltage V between the terminals of the charging socket 8 DC is compared, and if the boost voltage V B Equal to (branch is) the voltage V between the terminals of the charging socket 8 DC , then method 1 determines 520 that the negative DC switch 14 is welded, otherwise (branch no) method 1 determines 530 that the negative DC switch 14 is not welded. When charging does not use the boost stage, in the ninth comparison step 510, method 1 compares the inverter voltage V O On the other hand, the voltage V between the terminals of the charging socket 8 DC is compared, and if the inverter voltage V O Equal to (branch is) the voltage V between the terminals of the charging socket 8 DC , then method 1 determines 520 that the negative DC switch 14 is welded, otherwise (branch no) method 1 determines 530 that the negative DC switch 14 is not welded.

[0154] Similarly, when in the eighth comparison step 540 , method 1 determines that the common mode voltage V+ of the positive terminal of the charging socket 8 is greater than (branch No) the second lower common mode voltage limit S13 , then the eighth comparison step 540 is followed by a step 550 of controlling the negative DC switch to close.

[0155] After a few milliseconds, the control closing step 550 is followed by a tenth comparison step 560 in which, when charging uses the boost stage, the method 1 compares the boost voltage V B On the other hand, the voltage V between the terminals of the charging socket 8 DC is compared, and if the boost voltage V B Equal to (branch is) the voltage V between the terminals of the charging socket 8 DC , then method 1 determines 570 that the positive DC switch 13 is welded, otherwise (branch no) method 1 determines 580 that the positive DC switch 13 is not welded. When charging without using the boost stage 5, in the tenth comparison step 560, method 1 compares the inverter voltage V O On the other hand, the voltage V between the terminals of the charging socket 8 DC is compared, and if the inverter voltage V O Equal to (branch is) the voltage V between the terminals of the charging socket 8 DC , then method 1 determines 570 that the bypass switch 15 is welded, otherwise (branch no) method 1 determines 580 that the bypass switch 15 is not welded.

[0156] Of course, the invention is not limited to the examples that have just been described and many modifications can be made to these examples without departing from the scope of the invention.

Claims

1. A method (1) for terminating charging of a charging system (32) of an electric vehicle or hybrid vehicle (30) and for diagnosing a power switch (13, 14, 15, 16) of the charging system, the vehicle (30) comprising a traction battery (2) and an inverter (3) capable of supplying power to an electric motor (4) of the vehicle (30), the charging system (32) comprising at least: a switch (11), referred to as the positive battery switch, connected via a first of its terminals to the positive terminal of the traction battery (2) and via a second of its terminals to the positive input terminal of the inverter (3), and a switch (12) called the negative battery switch, connected via a first of its terminals to the negative terminal of the traction battery (2) and via a second of its terminals to the negative input terminal of the inverter (3), a boost stage (5), comprising at least one capacitor (6), the positive terminal of the at least one capacitor being connected to the positive input terminal of the boost stage (5), and the negative terminal of the at least one capacitor being connected to the negative input terminal of the boost stage (5), - two switches (13, 14, 15) called switches to be tested used during charging, when the charging uses the boost stage (5), the first switch to be tested (13, 15) being connected via a first of its terminals to the positive terminal of the charging socket (8) and via a second of its terminals to the positive input terminal of the boost stage (5), the second switch to be tested (14) being connected via a first of its terminals to the negative terminal of the charging socket (8) and via a second of its terminals to the second terminal of the negative battery switch (12), the method (1) comprising: - a step (110) of controlling the switches to be tested (13, 14, 15) to be opened, - On the one hand, the voltage (V DC ) with a predefined safety voltage (S1) on the other hand, a first comparison step (120), The method (1) further comprises: when the voltage (V DC ) is greater than the predefined safety voltage (S1): - On the one hand, the voltage (V DC ) with, on the other hand, the voltage between the second terminals of the switches to be tested (13, 14, 15), a second comparison step (130), The method (1) is characterized in that, when the charging uses the boost stage (5), when the difference between the voltages compared in the second comparison step (130) is less than a predefined voltage offset (S2), and in the absence of information about the closure of the charging flap of the vehicle (30) for access to the charging socket (8), the method (1) further comprises a step (140) of discharging the capacitor (6) and then, on the one hand, the voltage (V DC ) and on the other hand the voltage (V B ) is compared in a third comparison step (150).

2. The charge termination and diagnostic method (1) as claimed in claim 1, wherein: The motor (4) and the inverter (3) form part of a boost stage (5), the boost stage (5) comprising a switch (16) called a boost switch, connected via a first of its terminals to the positive terminal of the capacitor (6) and via a second of its terminals to the neutral point of the motor (4), the method (1) being characterized in that it comprises the following steps: when the boost stage (5) is used and when the method (1) does not diagnose any welding of the switches (13, 14) to be tested: - controlling the boost switch (16) to be turned off (180), - controlling (190) the inverter (3) to discharge the capacitor (6), - The voltage (V B ) or the phase current of the inverter (3) and the voltage of the capacitor (6) or the phase current (I B ) is compared (215) with the lower threshold value (S3, S4), and if the voltage (V B ) is less than the lower threshold value (S3) of the voltage of the capacitor (6), or if the phase current (I B ) is greater than the phase current (I B ) of the lower threshold (S4), the welding of the boost switch (16) is detected (230).

3. The charge termination and diagnostic method (1) according to claim 1 or 2, wherein: The charging system (32) comprises: a switch (13), referred to as the positive DC switch, connected via a first of its terminals to the positive terminal of the charging socket (8) and via a second of its terminals to the positive input terminal of the boost stage (5), and a switch (14), referred to as a negative DC switch, connected via a first of its terminals to the negative terminal of the charging socket (8) and via a second of its terminals to the negative input terminal of the boost stage (5), When the charging uses the boost stage (5), the switches to be tested are the positive DC switch (13) and the negative DC switch (14), and the voltage (V B ) is then called the boost voltage.

4. The charge termination and diagnostic method (1) as claimed in claim 3, wherein: The charging system (32) includes a switch (15) called a bypass switch, which is connected to the first terminal of the positive DC switch (13) through a first terminal of its terminals and to the second terminal of the positive battery switch (11) through a second terminal of its terminals. When the charging does not use the boost stage (5), the switches to be tested are the negative DC switch (14) and the bypass switch (15). The voltage (V O ) is then called the inverter voltage.

5. The charge termination and diagnostic method (1) as claimed in claim 4, wherein: When it has been detected (135) that the charging flap is closed, regardless of whether the charging uses the boost stage (5), the bypass switch (15), the positive DC switch (13) and the negative DC switch (14) are controlled to be open (240) and the positive battery switch (11) and the negative battery switch (12) are controlled to be closed (240), the voltage (V) between the terminals of the charging socket (8) is compared after the second comparison step (130). DC ) with at least one of the lower differential voltage threshold (S5) and the intermediate differential voltage threshold (S6), so that if the voltage (V DC ) is greater than the intermediate differential voltage threshold (S6), the welding (290) of the bypass switch (15) and the negative DC switch (14) is detected, or if the voltage (V DC ) is between the low differential voltage threshold (S5) and the middle differential voltage threshold (S6), then the welding (270) of the positive DC switch (13) and the negative DC switch (14) is detected.

6. The charge termination and diagnostic method (1) as claimed in claim 5, wherein: When the fourth comparison step (250) determines the voltage (V DC ) is less than the low differential voltage threshold (S5), then after the fourth comparison step (250), a fifth comparison step (300) is performed of comparing the common mode voltage (V+) of the positive terminal of the charging socket (8) on the one hand with at least one common mode voltage threshold of the low common mode voltage threshold (S8) and the intermediate common mode voltage threshold (S9) on the other hand, thereby concluding that when the common mode voltage (V+) of the positive terminal of the charging socket (8) is less than the low common mode voltage threshold (S8), the bypass The switch (15) and the positive DC switch (13) have not yet been welded (310), or if the common mode voltage (V+) of the positive terminal of the charging socket (8) is between the low common mode voltage threshold (S8) and the intermediate common mode voltage threshold (S9), the positive DC switch (13) has been welded (330), or if the common mode voltage (V+) of the positive terminal of the charging socket (8) is greater than the intermediate common mode voltage threshold (S9), the bypass switch (15) has been welded (350).

7. A charge termination and diagnostic method (1) as claimed in claim 5 or 6, wherein: When the fourth comparison step (250) determines the voltage (V DC ) is less than the low differential voltage threshold (S5), then after the fourth comparison step (250), a sixth comparison step (360) is performed to compare the common mode voltage (V-) of the negative terminal of the charging socket (8) on the one hand with the low common mode voltage level (S11) on the other hand, thereby concluding that when the common mode voltage (V-) of the negative terminal of the charging socket (8) is less than the low common mode voltage level (S11), the negative DC switch (14) has not yet been welded (370), otherwise the negative DC switch (14) has been welded (380).

8. A charge termination and diagnostic method (1) as claimed in any one of claims 4 to 7, wherein: When the charging is not performed using the boost stage (5), when the difference between the voltages compared in the second comparison step (130) is less than a predefined voltage offset (S2), and in the absence of information about the closure of the charging flap of the vehicle (30) for access to the charging socket (8), the method (1) continues with the following steps: - controlling the positive battery switch and the negative battery switch (13, 14) to be disconnected (390), - The voltage (V DC ) is additionally compared (400) with the predefined safety voltage (S1), and if the voltage (V DC ) is less than the predefined safety voltage (S1), the following operations are performed: - controlling the positive battery switch and the negative battery switch (13, 14) to close (410), - The voltage (V DC ) is additionally compared (420) with the predefined safety voltage (S1), and if the voltage (V DC ) is greater than the predefined safety voltage (S1), then the welding of the negative DC switch (14) and the bypass switch (15) is detected (430); otherwise, it is concluded that at least one of the bypass switch (15) and the negative DC switch (14) is not welded.

9. The charge termination and diagnostic method (1) of claim 8, wherein: The voltage (V DC ) with the predefined safety voltage (S1), when the voltage (V DC ) is greater than the predefined safety voltage (S1), the method proceeds to the following steps: - Change the inverter voltage (V O ) is compared with the predefined safety voltage (S1) (440), thereby concluding that when the inverter voltage (V O ) is less than the predefined safety voltage (S1), at least one of the bypass switch (15) and the negative DC switch (14) is not welded, otherwise the charging cable (70) connected to the charging socket (8) is prevented (460) from being disconnected, and the step loops back to the additional comparison step (400).

10. A charge termination and diagnostic method (1) as claimed in any one of claims 3 to 9, wherein: When the third comparison step (150) determines the voltage (V DC ) is equal to the boost voltage (V B ), the method (1) detects (160) the welding of the positive DC switch (13) and the negative DC switch (14), otherwise the method (1) determines that at least one of the positive DC switch (13) and the negative DC switch (14) is not welded.

11. A charge termination and diagnostic method (1) as claimed in any one of claims 3 to 10, wherein: When the charging uses the boost stage (5), and when the first comparison step (120) determines the voltage (V DC ) is less than the predefined safety voltage (S1), or when the second comparison step (130) determines that the boost voltage (V B ) and the voltage (V DC ) is greater than the predefined voltage offset (S2), the method (1) determines that at least one of the positive DC switch (13) and the negative DC switch (14) is not welded.

12. A charge termination and diagnostic method (1) as claimed in any one of claims 4 to 11, wherein: When the charging is not performed using the boost stage (5), and when the first comparison step (120) determines the voltage (V DC ) is less than the predefined safety voltage (S1), or when the second comparison step (130) determines that the voltage of the inverter (V O ) and the voltage (V DC ) is greater than the predefined voltage offset (S2), the method (1) determines that at least one of the bypass switch (15) and the negative DC switch (14) is not welded.

13. A charge termination and diagnostic method (1) as claimed in any one of claims 8 to 12 when dependent on claim 4, wherein: When the method (1) determines that at least one of the positive DC switch (13) and the negative DC switch (14) is not welded when the charging uses the boost stage (5) or determines that at least one of the bypass switch (15) and the negative DC switch (14) is not welded when the charging does not use the boost stage (5), the method (1) continues with the negative DC switch (14) and the positive DC switch (13) or the bypass switch (15) being controlled to be disconnected (470), respectively, by comparing the common mode voltage (V-) of the negative terminal of the charging socket (8) with a first lower common mode voltage limit (S12). A seventh comparison step (480) is performed, whereby it is concluded that when the common mode voltage (V-) of the negative terminal of the charging socket (8) is less than the first low common mode voltage limit (S12), the negative DC switch (14) has not yet been welded (490), and the method continues with an eighth comparison step (540) of comparing the common mode voltage (V+) of the positive terminal of the charging socket (8) on the one hand with the second low common mode voltage limit (S13) on the other hand, whereby it is concluded that when the common mode voltage (V+) of the positive terminal of the charging socket (8) is less than the second low common mode voltage limit (S13), the positive DC switch (13) or the bypass switch (15), respectively, has not yet been welded (545).

14. The charge termination and diagnostic method (1) of claim 13, wherein: When the common mode voltage (V-) of the negative terminal of the charging socket (8) is greater than the first low voltage limit (S12), the method (1) continues to respectively increase the boost voltage (V B ) or the inverter voltage (V O ) and the voltage (V DC ) is compared in the ninth comparison step (510), so that if the boost voltage (V B ) or the inverter voltage (V O ) are respectively equal to the voltage (V DC ), the welding of the negative DC switch (14) is detected (520), otherwise it is concluded that the negative DC switch (14) has not been welded (530).

15. A charge termination and diagnostic method (1) as claimed in claim 13 or 14, wherein: When the common mode voltage (V+) of the positive terminal of the charging socket (8) is greater than the second low voltage limit (S13), the method (1) continues to respectively increase the boost voltage (V B ) or the inverter voltage (V O ) and the voltage (V DC ) is compared in the tenth comparison step (560), so that if the boost voltage (V B ) or the inverter voltage (V O ) are respectively equal to the voltage (V DC ), the welding of the positive DC switch (13) or the bypass switch (15) is detected (570), otherwise it is concluded that the positive DC switch (13) or the bypass switch (15) has not been welded (580).

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