Method for diagnosing charge completion and switch on a charging system for an electric or hybrid vehicle

Abstract

The present invention relates to a method for stopping charging and diagnosing switches (13, 14, 15, 16) of a charging system (32) of an electric vehicle (30) having a voltage booster (5) with a capacitor (6) connected to an input terminal and two switches (13, 14) connected to separate terminals of a charging socket (8), the method including instructions to open the switches (13, 14, 15, 16) and to detect a voltage (V) at the terminals of the socket (8). DC ) is higher than the safe voltage, the voltages downstream and upstream of the switches (13, 14, 15, 16) are similar, the load uses a voltage booster (5) and there is no information about the closure of the charging lid, the method discharges the capacitor (6) and then the voltage (V DC ) to the downstream voltage (V B )

Description

Summary of the Invention

[0001] The present invention relates to the field of automotive and electrical engineering, and more precisely to a method for charge termination and power switch diagnostics of a charging system for an electric or hybrid vehicle.

[0002] Electric or hybrid vehicles typically have a high-voltage traction battery, which becomes depleted as AC power is supplied to the vehicle's electric traction motor via an inverter. Therefore, the vehicle requires a system for charging the traction battery. Such a system recharges the traction battery by recovering energy during vehicle braking or by drawing energy from a charging station external to the vehicle. DC charging stations, in particular, can deliver a charging voltage higher than the traction battery's voltage, on the order of several hundred volts, allowing the traction battery to be charged very quickly.

[0003] To enable such rapid charging, the charging system must include a power switch that allows the traction battery to be electrically connected to a DC charging station. The very large currents delivered by such charging stations, potentially reaching hundreds of amperes, can damage such switches. In particular, if such switches are mechanical relays, passing too much current through the switch can cause the switch terminals to fuse together, preventing the switch from being turned off. In the case of MOSFETs (MOSFET stands for Metal-Oxide-Semiconductor Field-Effect Transistor), passing too much current through the switch can also damage the switch substrate, preventing the switch from being turned off again. In either case, the power switch is considered to be "welded." In this patent application, the term "welded" should be understood to mean, specifically, in the case of mechanical relays, that the terminals of the switch are held in a welded state, or, in the case of MOSFETs, that the switch is damaged to the point where it cannot be turned off.

[0004] To ensure the electrical safety of vehicle users when charging begins or is completed and to prevent subsequent vehicle failure as a result of such damage to the power switch, the vehicle's computer typically diagnoses the power switch between the vehicle's charging socket and the vehicle's traction battery, which is upstream of the power switch that connects the vehicle's traction battery to the inverter. To perform this diagnosis, the vehicle communicates with the charging station. When the charging station receives an indication that the vehicle has initiated such a diagnostic process, it must open its own power switch, i.e., reduce the charging voltage to zero and stop delivering charging current to the vehicle.

[0005] Furthermore, because some vehicles now have traction batteries capable of a maximum no-load voltage that is much higher than the maximum voltage level available from conventional charging stations that deliver a maximum voltage of less than 500V (volts), in such vehicles the charging socket used for DC charging is no longer directly connected to the vehicle's traction battery, but rather to the input of a voltage step-up stage whose output is connected to the traction battery.

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

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

[0008] Due to the position of these power switches being diagnosed, if the voltage across the terminals of the charging socket is too high while the charging socket is still connected to the station, it is difficult for the vehicle computer to distinguish between: - problems resulting from both, on the one hand, the welding of a power switch of the charging station and on the other hand, the welding of a power switch connecting the traction battery of the vehicle to the inverter of the vehicle, so that the voltage level of the battery is substantially the same as the voltage level delivered by the charging station; - On the other hand, problems caused solely by the welding of the power switch being diagnosed.

[0009] In these two cases, it is dangerous for the vehicle user to disconnect the charging cable.

[0010] Therefore, there is a need to ensure the safety of electric or hybrid vehicle users by properly diagnosing the good operation or malfunction of power switches downstream of the vehicle's charging socket and upstream of the power switch that connects the vehicle's traction battery to the vehicle's inverter, which may also be upstream of the input of the vehicle's voltage boost stage depending on the configuration of the vehicle's charging system.

[0011] The present invention aims to at least partially remedy the drawbacks of the prior art by providing a method for terminating charging and diagnosing power switches in a charging system of an electric or hybrid vehicle equipped with a voltage boost stage, which method makes it possible, by clever use of the voltage boost stage, to obtain a diagnosis of welding of each of the switches used to charge the vehicle's battery via the voltage boost stage, and also makes it possible to increase the electrical safety of the user.

[0012] To achieve this object, the present invention provides a method for terminating charging and diagnosing a power switch of a charging system for an electric or hybrid vehicle, the vehicle comprising a traction battery and an inverter capable of powering an electric motor of the vehicle, and the charging system comprising at least: - a switch, called a positive battery switch, connected at a first terminal to the positive terminal of the traction battery and at a second terminal to the positive input terminal of the inverter; and - a switch called the negative battery switch, connected with its first terminal to the negative terminal of the traction battery and with its second terminal to the negative input terminal of the inverter; a voltage boost stage comprising at least one capacitor, the positive terminal of which is connected to the positive input terminal of the voltage boost stage and the negative terminal of which is connected to the negative input terminal of the voltage boost stage; - two switches, called test switches, used during charging, the first test switch having a first terminal connected to the positive terminal of the charging socket and a second terminal connected to the positive input terminal of the voltage boost stage if a voltage boost stage is used for charging, and the second test switch having a first terminal connected to the negative terminal of the charging socket and a second terminal connected to the second terminal of the negative battery switch. The method includes: - controlling the switch under test to an open state; a first comparison step between the voltage across the terminals of the charging socket on the one hand and a predetermined safety voltage on the other hand, The method further includes, when the voltage across the terminals of the charging socket is higher than a predetermined safe voltage: a second comparison step between the voltage across the terminals of the charging socket on the one hand and the voltage across second terminals of the switch under test on the other hand; The method is characterized in that a voltage boost stage is used for charging, and if the difference between the voltages compared in the second comparison step is less than a predetermined voltage offset and there is no information about the closure of a charging lid of the vehicle used to access the charging socket, the method additionally comprises a step of discharging the capacitor, and then a third comparison step between the voltage across the terminals of the charging socket on the one hand and the voltage across the second terminals of the switch under test on the other hand.

[0013] It should be noted that the voltages compared in this method according to the present invention are positive or absolute voltage values ​​unless otherwise specified. Additionally, the steps of this method are referred to in the order in which they are performed. These steps are performed at least in part by the vehicle's computer at the end of DC charging of the traction battery using a vehicle's charging socket connected to a DC charging station via a charging cable.

[0014] It should also be noted that the connections described in this patent application in relation to the terminals of the switches are direct connections, i.e. connections made by components with zero or near-zero resistance whose only function is to conduct electricity, except in the case where they may serve as fuses or additional switches that do not form part of the subject matter of the present invention. Such switches are power switches, for example mechanical relays or MOSFETs. The first and second terminals of each switch correspond to terminals of separate switches.

[0015] Additionally, in this patent application, unless otherwise stated, a connection to an input or output of a functional assembly such as an inverter or a voltage step-up stage is to be understood as a connection to an input terminal or an output terminal, respectively, i.e. a parallel connection to the input or output, respectively, where the output (with respect to the inverter function) of the inverter is in particular connected to the phase connections of the electric motor of the vehicle.

[0016] It should be understood that the traction battery, also in this patent application, is the battery that powers the inverter and electric motor when the vehicle is in operation, and is distinct from the vehicle's auxiliary battery, which powers the vehicle's low-voltage electrical network (e.g., 14 V) to which various consumers, including the vehicle's main computer, are connected. The traction battery may therefore also be understood as a propulsion battery depending on the electric motor used. Unless otherwise specified, in this patent application, battery refers to the vehicle's traction battery. Similarly, in this patent application, the terms "motor" and "inverter" refer to the vehicle's electric traction or drive motor and the vehicle's traction or drive inverter, unless otherwise indicated. Finally, the terms "charging" and "recharging" are considered synonymous in this patent application.

[0017] In the third comparison step of the method according to the invention, charging uses a voltage boost stage of the vehicle, the input of the voltage boost stage being connected to the charging station and the output of the voltage boost stage being connected to the terminals of the traction battery. In this patent application, "using a voltage boost stage" means that the charging current flows through the voltage boost stage, which is the systemic case when the charging system does not have a means for directly connecting the charging station and the traction battery.

[0018] By discharging the capacitor before the third comparison step, the voltage across the terminals of the charging socket during the third comparison step should be different from the voltage across the second terminal of the switch under test if both switches under test are not welded, otherwise the switch under test would be diagnosed as welded, which was not possible in the prior art because the voltage across the terminals of the capacitor was in all cases substantially equal to the charging voltage, which prevented the elimination of welded switches in the charging station.

[0019] The third step is performed when the vehicle's computer does not have information about whether the user will be exposed to a dangerous voltage in the vehicle when the charging cable is not plugged in, for example, when the vehicle does not have a charging lid closure sensor or when this sensor is faulty. Therefore, the user is only allowed to completely safely disconnect the charging cable if the diagnosis performed following the third comparison step diagnoses that at least one of the two tested switches is not welded.

[0020] The invention therefore allows for more detailed diagnostics of the switches used during charging with a voltage boost stage, allowing the user to disconnect the charging cable without risking electric shock.

[0021] In one approach to carrying out the invention, the motor and inverter form part of a voltage boost stage, the voltage boost stage including a switch, referred to as a boost switch, connected at a first terminal to the positive terminal of the capacitor and at a second terminal to the neutral point of the motor, the method using the voltage boost stage for charging, and when the method is not diagnosing a welded switch under test, includes the following steps: - controlling the boost switch to an open state; - controlling the inverter to discharge the capacitor; comparing the voltage across the capacitor or the phase current of the inverter with a capacitor lower voltage threshold or a phase current lower threshold, respectively, and detecting a welded boost switch if the voltage across the capacitor is lower than the capacitor lower voltage threshold or the phase current of the inverter is higher than the phase current lower threshold. Otherwise, if the voltage across the capacitor is higher than the capacitor lower voltage threshold or the inverter phase current is zero for a certain period of time immediately after a discharge command, the method determines that the boost switch is not welded.

[0022] The motor of the charging system is an AC motor, e.g., a three-phase motor. In this approach to implementing the invention, the stator inductance of the three-phase motor is used as the current storage inductance of the voltage boost stage, which discharges through the inverter to the traction battery during a duty cycle of the inverter switches that is set in response to, among other things, voltage or current measurements made by the charging system. By reusing components used for vehicle traction to form the voltage boost stage, space in the engine compartment is saved, as well as the cost of using specific components to produce the stage.

[0023] Diagnostics of the boost switch can ensure proper operation of the vehicle after charging using the boost switch. Specifically, if this switch were to weld, the parallel capacitors of the motor and inverter could degrade the operation of the vehicle while in operation.

[0024] The charging system comprises, in particular: - a switch called a positive DC switch, which has a first terminal connected to the positive terminal of the charging socket and a second terminal connected to the positive input terminal of the voltage boost stage; and - A switch called a negative DC switch, which has its first terminal connected to the negative terminal of the charging socket and its second terminal connected to the negative input terminal of the voltage boost stage. The switch under test is a positive DC switch and a negative DC switch when a voltage boost stage is used for charging, and the voltage across the second terminal of the switch under test, which in this case is called the boost voltage, also corresponds to the voltage across the terminals of the capacitor.

[0025] In one embodiment of the present invention, the charging system includes a switch, called a bypass switch, connected at a first terminal to a first terminal of the positive DC switch and at a second terminal to a second terminal of the positive battery switch 11; The switch under test is the negative DC switch and the bypass switch if no voltage boost stage is used for charging, and the voltage across the second terminal of the switch under test is called the inverter voltage in this case.

[0026] In this embodiment of the invention, the charging system comprises means for connecting the charging station directly to the traction battery, i.e., when such direct connection means are used, without passing through a voltage step-up stage, but through only a small number of conductors or components with zero or near-zero resistance, such as a battery switch, which separates the charging socket from the traction battery.

[0027] Such direct connection means are advantageously used when the vehicle is connected to a charging station that provides a charging voltage higher than the maximum no-load voltage of the traction battery. The charging current delivered from such a charging station does not pass through the voltage boost stage, so there are no electrical losses in the voltage boost stage. In addition, this eliminates the need to overspecify the vehicle's electric motor and inverter to be able to withstand the charging current delivered from such a charging station.

[0028] This embodiment optimizes the number of switches in the charging system according to the present invention, including this direct connection, because the negative DC switch is used for both charging the traction battery using the voltage boost stage and charging the battery without the voltage boost stage. This direct connection embodiment eliminates the need to close the positive DC relay when charging the traction battery without the voltage boost stage. Additionally, this embodiment eliminates the need to couple the capacitor at the input of the voltage boost stage with a smoothing capacitor connected to the input of the traction battery, which could have adverse effects on the charging or charging system when charging the traction battery without the voltage boost stage.

[0029] The invention therefore applies to charging systems that use a voltage boost stage to charge at least the traction battery when the charging voltage delivered from the charging station is lower than the maximum no-load voltage of the battery, and the charging system may also comprise direct connection means to the battery, in which case these direct connection means are used when the charging voltage delivered from the charging station is higher than the maximum no-load voltage of the battery.

[0030] According to one advantageous feature of the method according to the invention, if the charging system comprises means for direct connection to the battery and closure of the charging lid is detected, the second comparison step is followed by a fourth comparison step in which the bypass switch, the positive DC switch and the negative DC switch are controlled to an open state and the positive battery switch and the negative battery switch are controlled to a closed state, regardless of whether a voltage boost stage was used for charging or not, and a fourth comparison step is carried out between the voltage across the terminals of the charging socket on the one hand and at least one differential voltage threshold of the lower differential voltage threshold and the middle differential voltage threshold on the other hand, so that if the voltage across the terminals of the charging socket is higher than the middle differential voltage threshold, welding of the bypass switch and the negative DC switch is detected, or if the voltage across the terminals of the charging socket is between the lower differential voltage threshold and the middle differential voltage threshold, welding of the positive DC switch and the negative DC switch is detected.

[0031] Advantageously, if the fourth comparison step determines that the voltage across the terminals of the charging socket is lower than the lower differential voltage threshold, the fourth comparison step is followed by a fifth comparison step of the common mode voltage of the positive terminal of the charging socket on the one hand and at least one common mode voltage threshold of the lower common mode voltage threshold and the middle common mode voltage threshold on the other hand, such that a conclusion is reached that the bypass switch and the positive DC switch are not welded if the common mode voltage of the positive terminal of the charging socket is lower than the lower common mode voltage threshold, or that the positive DC switch is welded if the common mode voltage of the positive terminal of the charging socket is between the lower common mode voltage threshold and the middle common mode voltage threshold, or that the bypass switch is welded if the common mode voltage of the positive terminal of the charging socket is higher than the middle common mode voltage threshold.

[0032] Also advantageously, if the fourth comparison step determines that the voltage across the terminals of the charging socket is lower than the lower differential voltage threshold, the fourth comparison step is followed by a sixth comparison step of the common mode voltage at the negative terminal of the charging socket, on the one hand, and the low-level common mode voltage, on the other hand, so that if the common mode voltage at the negative terminal of the charging socket is lower than the low-level common mode voltage, a conclusion is reached that the negative DC switch is not welded, or otherwise a conclusion is reached that the negative DC switch is welded. The fifth and sixth comparison steps are, for example, performed in parallel after the fourth comparison step.

[0033] Various differential or common mode voltage thresholds allow the user to disconnect the plug from the socket and diagnose a welded one of the bypass switch and the positive and negative DC switches despite the fact that the two switches used for charging are not known a priori.

[0034] In another example of use of the method according to the invention, if no voltage boost stage is used for charging, the difference between the voltages compared in the second comparison step is less than a predetermined voltage offset and there is no information about the closure of a charging lid of the vehicle used to access the charging socket, the method proceeds to the following steps: - controlling the positive battery switch and the negative battery switch to an open state; - proceeding to a step of further comparing the voltage across the terminals of the charging socket with a predetermined safety voltage, and if the voltage across the terminals of the charging socket is lower than the predetermined safety voltage; - controlling the positive battery switch and the negative battery switch to a closed state; - Proceed to a step of further comparing the voltage between the terminals of the charging socket with a predetermined safety voltage, and if the voltage between the terminals of the charging socket is higher than the predetermined safety voltage, detect welding of the negative DC switch and the bypass switch, and if not, conclude that at least one of the bypass switch and the negative DC switch is not welded.

[0035] Thus, in this use case, the method according to the present invention exploits the voltage differences measured as a function of the state of the positive and negative battery switches to perform diagnostics on the negative DC switch and the bypass switch.

[0036] In this further example of use of the method according to the invention, if upon further comparison of the voltage across the terminals of the charging socket with the predetermined safety voltage, the voltage across the terminals of the charging socket is higher than the predetermined safety voltage, the method proceeds to the following step: - Proceed to a step of comparing the inverter voltage with a predetermined safety voltage, and if the inverter voltage is lower than the predetermined safety voltage, a conclusion is drawn that at least one of the bypass switch and the negative DC switch is not welded, otherwise the charging socket is prevented from disconnecting the connected charging cable, and this step loops back to a further comparison step.

[0037] The present invention therefore minimizes the cases where a user is not permitted to disconnect the charging plug from the socket.

[0038] Returning to a more general example of use of the present invention, according to another advantageous feature of the method of the present invention, if the third comparison step determines that the voltage between the terminals of the charging socket is equal to the boosted voltage, the method detects that the positive DC switch and the negative DC switch are welded, and if not, the method determines that at least one of the positive DC switch and the negative DC switch is not welded. Of course, considering the level of the voltages being compared, the equality between the voltages in this patent application is evaluated within a tolerance of a few volts.

[0039] Additionally, advantageously, the method according to the present invention uses a voltage boost stage for charging, and if the first comparison step determines that the voltage across the terminals of the charging socket is lower than a predetermined safe voltage, or if the second comparison step determines that the difference between the boosted voltage and the voltage across the terminals of the charging socket is greater than a predetermined voltage offset, the method determines that at least one of the positive and negative DC switches is not welded.

[0040] Similarly, if the voltage boost stage is not used for charging and the first comparison step determines that the voltage across the terminals of the charging socket is less than a predetermined safe voltage, or if the second comparison step determines that the difference between the inverter voltage and the voltage across the terminals of the charging socket is greater than a predetermined voltage offset, the method determines that at least one of the bypass switch and the negative DC switch is not welded.

[0041] Also advantageously, if the method according to the invention uses a voltage boost stage for charging and determines that at least one of the positive and negative DC switches is not welded, or if the method does not use a voltage boost stage for charging and determines that at least one of the bypass switch and the negative DC switch is not welded, the method controls the negative DC switch on the one hand and the positive DC switch or the bypass switch on the other hand to an open state, and controls the common mode voltage of the negative terminal of the charging socket on the one hand and the first common mode voltage on the other hand. The process proceeds to a seventh comparison step with the first common mode voltage lower limit, and as a result, if the common mode voltage of the negative terminal of the charging socket is lower than the first common mode voltage lower limit, a conclusion is reached that the negative DC switch is not welded; and the process proceeds to an eighth comparison step with the common mode voltage of the positive terminal of the charging socket on the one hand and the second common mode voltage lower limit, and as a result, if the common mode voltage of the positive terminal of the charging socket is lower than the second common mode voltage lower limit, a conclusion is reached that the positive DC switch or the bypass switch is not welded.

[0042] The seventh and eighth comparison steps are, for example, performed in parallel.

[0043] Advantageously, if during the seventh comparison step, the common-mode voltage of the negative terminal of the charging socket is higher than the first lower voltage limit, the method according to the present invention controls the positive DC switch or the bypass switch to a closed state, and then proceeds to a ninth comparison step of comparing the boost voltage or the inverter voltage on the one hand with the voltage across the terminals of the charging socket on the other hand, so that if the boost voltage or the inverter voltage is equal to the voltage across the terminals of the charging socket, a welding of the negative DC switch is detected; otherwise, a conclusion is reached that the negative DC switch is not welded.

[0044] Advantageously, if in the eighth comparison step the common mode voltage of the positive terminal of the charging socket is higher than the second lower voltage limit, the method controls the negative DC switch to a closed state, and then proceeds to a tenth comparison step of comparing the boost voltage or inverter voltage on the one hand with the voltage across the terminals of the charging socket on the other hand, so that if the boost voltage or inverter voltage is equal to the voltage across the terminals of the charging socket, a fusion of the positive DC switch or bypass switch is detected; otherwise, a conclusion is reached that the positive DC switch or bypass switch is not fused.

[0045] Other characteristics and advantages of the invention will become more apparent from the following description on the one hand and from the several non-limiting examples of embodiment presented by way of indication with reference to the attached schematic drawings, in which: [Brief explanation of the drawings]

[0046] [Figure 1] FIG. 1 is a schematic diagram illustrating an electric or hybrid vehicle connected to a charging station, equipped with a charging system, and implementing a method for terminating vehicle charging and diagnosing a power switch of the charging system according to the present invention, in accordance with an embodiment of the present invention. [Figure 2]1 illustrates the first step of a method for terminating and diagnosing charging according to the present invention, as implemented by the vehicle of FIG. 1, when the charging has just been completed using the voltage boost stage of the vehicle's charging system. [Figure 3] 3 shows the steps following the initial steps of the method for terminating and diagnosing charging of FIG. 2 if the switch between the charging station and the voltage boost stage is not diagnosed as welded in the initial steps. [Figure 4] 3 illustrates the steps following the initial steps of the charging termination and diagnostic method of FIG. 2 when voltage remains across the terminals of the charging socket and the closure of the charging lid blocking access to the charging socket is flagged by the vehicle's computer implementing the method according to the present invention. [Figure 5] FIG. 2 illustrates the first step of a method for terminating and diagnosing charging according to the present invention, as implemented by the vehicle of FIG. 1, when charging has just been completed and the voltage boost stage of the vehicle's charging system has not been used. [Figure 6] 6 shows the steps following the first step of the method for terminating and diagnosing charging of FIG. 5 when voltage remains across the terminals of the charging socket and the vehicle computer implementing the method according to the invention does not have information about the possibility of closure of the charging lid. [Figure 7] 7 shows the steps of the method for terminating and diagnosing charging of FIG. 2, FIG. 5 or FIG. 6 followed by the steps when the method according to the present invention is used during charging to determine that at least one of the switches upstream of the voltage boost stage or the switch allowing direct connection of the charging socket to the traction battery is not welded. DETAILED DESCRIPTION OF THE INVENTION

[0047] According to one embodiment of the present invention, the electric or hybrid vehicle 30 shown in Figure 1 includes a charging system 32. The vehicle 30 includes a traction battery 2, and the charging system 32 immediately enables the vehicle 30 to recharge the traction battery 2 with energy provided from a DC charging station 60 connected by a charging cable 70. At the end of DC charging, the vehicle implements a charge termination and power switch diagnostic method 1 for the charging system 32 according to the present invention, as shown in Figures 2 to 7.

[0048] To clarify how these power switches are used during charging of the traction battery 2, the charging system 32 will now be described with reference to FIG. 1 and other elements of the vehicle 30.

[0049] The vehicle comprises a traction inverter 3 and a three-phase electric motor 4 connected to the wheels of the vehicle by a drive train, the inverter 3 and motor 4 being powered by a traction battery 2 to move the vehicle.

[0050] For this purpose, the vehicle includes a first switch 11, referred to as the positive battery switch, connected at its first terminal to the positive terminal of the traction battery 2 and at its second terminal to the positive input terminal of the inverter 3, and a second switch 12, referred to as the negative battery switch, connected at its first terminal to the negative terminal of the traction battery 2 and at its second terminal to the negative input terminal of the inverter 3, to connect the traction battery 2 to the inverter 3. Here, the inverter input refers to the part of the inverter that receives DC current and outputs rectified current; i.e., the term "input" should be understood to refer to the inverter function. Similarly, in this patent application, the terms "input" and "output" should be understood to refer to the function of the referenced electrical assembly or component. A smoothing capacitor 7 is connected to the inverter input. This capacitor allows smoothing of the current entering the battery 2 when the inverter 3 is used as a rectifier for the current output from the electric motor 4 operating in generator mode.

[0051] The positive battery switch 11 and the negative battery switch 12 therefore form the means for connecting the traction battery 2 to the input of the inverter 3. Furthermore, the output of the inverter 3 is connected directly to the electric motor 4, i.e. without any intermediate switches.

[0052] The vehicle also comprises a charging socket 8, which is connected to the DC charging station 60 via a charging cable 70. This charging socket 8 is, for example, a CHAdeMO connector in accordance with the IEC 61851-23, -24 standard. In a variant, the vehicle comprises only one charging socket that can be connected to both a DC charging station and an AC charging station, for example a combo DC charging socket in accordance with the IEC 62196-3 standard. In this case, the vehicle 30 also comprises AC charging means. In yet another variant, the vehicle comprises only one charging socket that is intended to be connected exclusively to a DC charging station.

[0053] The charging system 32 comprises an inverter 3, a motor 4, and a voltage boost stage 5, which comprises a capacitor 6 connected to the input of the voltage boost stage 5. More precisely, the positive terminal of the capacitor 6 is connected to the neutral point of the motor 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 voltage boost stage 5 is used by the vehicle to charge the traction battery 2 using a charging voltage supplied from a charging station that is lower than the maximum no-load voltage of the traction battery 2.

[0054] To do this, the charging system 32 comprises means 40 for controlling the inverter 3 and the motor 4, which are able to convert the charging voltage input to the voltage boost stage 5 into a voltage output from the voltage boost stage 5 that is higher than the voltage of the traction battery 2. The stator inductance of the electric motor 4 is in this case used as a current storage inductance for the voltage boost stage 5, which discharges through the inverter 3 to the traction battery 2 during a duty cycle of switching of the inverter 3 set by the control means 40, and the control means furthermore controls the voltage V across the terminals of the capacitor 6. B The charging system 32 measures the voltage V B In addition to the measurement means for at least one phase current I flowing through the inverter 3 B The device is provided with a measuring means.

[0055] A switch 16, called boost switch, has a first terminal connected to the positive terminal of the boost capacitor 6 and a second terminal connected to the neutral point of the electric motor 4. The boost switch 16 is able to disconnect the boost capacitor 6 at the input of the voltage boost stage 5, except during the charging phase of the traction battery 2 by an external charging station, and the boost switch 16 is kept in an open state in particular when the vehicle is being driven. Thus, capacitive coupling of the boost capacitor 6 with the electric motor 4 is avoided when the vehicle is being driven.

[0056] The control means 40 of the inverter 3 is for example a microcontroller which controls the switches of the inverter 3 both in traction mode and in charging mode of the vehicle using the voltage boost stage 5 .

[0057] The charging system 32 additionally comprises means for connecting the charging socket 8 to the input of the voltage boost stage 5, such means comprising: a switch 13, called positive DC switch, connected with a first terminal to the positive terminal of the charging socket 8 and with a second terminal to the boost switch 16; and a switch 14 called negative DC switch, which is connected with a first terminal to the negative terminal of the charging socket 8 and with a second terminal to the negative input terminal of the inverter 3;

[0058] These switches 13, 14 are used to recharge the traction battery 2 via the voltage boost stage 5 when the charging voltage of the charging station to which the charging socket 8 is connected is lower than the maximum no-load voltage of the battery 2.

[0059] Finally, the charging system 32 also comprises means for connecting the charging socket 8 directly to the traction battery 2, which means are used to recharge the battery when the charging voltage of the charging station to which the charging socket 8 is connected is higher than the maximum no-load voltage of the battery 2. Such connection means comprise a negative DC switch 14 and a switch 15, called a bypass switch, which has a first terminal connected to the first terminal of the positive DC switch 13 and a second terminal connected to the second terminal of the positive battery switch 11.

[0060] The 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-charging relay 10, which is connected at one terminal to the positive terminal of the traction battery 2 and at the other terminal to the positive terminal of the inverter 3. A pre-charging resistor is connected between the pre-charging relay 10 and the positive terminal of the battery 2. Before charging the battery 2, the pre-charging relay 10 is first closed to charge the smoothing capacitor 7, and then the pre-charging relay 10 is opened and the positive battery switch 11 is closed. The pre-charging relay 10 and the pre-charging resistor form a pre-charging device. It should be noted that other types of pre-charging devices may be used instead of such a relay and resistor system.

[0061] The charging system 32 also comprises one or more software and / or hardware modules of a main computer 50 of the vehicle. The main computer 50 comprises, in particular, means for communication with the charging station 60 and means for controlling the power switches 10, 11, 12, 13, 14, 15 and 16, which communication and control means form part of the charging system 32. The control means for the power switches 10, 11 and 12 may also be present in a system 20 managing the traction battery 2, the management system of which is in communication with the main computer 50 and which may form an integral part of the charging system 32.

[0062] The system 20 managing the traction battery 2 controls the current entering the battery and the voltage V between the terminals of the charging socket 8. DC The charging socket 8 is coupled to a sensor 22, which allows the charging of the battery 2 to be monitored. DCis the differential voltage between the two terminals of the charging socket 8. The system 20 managing the battery 2 also comprises means for controlling the bypass switch 15, as well as the positive DC switch 13 and the negative DC switch 14. Therefore, if the system 20 managing the battery 2 detects a fault during charging, the system 20 may interrupt charging for safety reasons without intervention by the vehicle's main computer 50. Therefore, the switches 10, 11, 12, 13, 14, and 15 are controllable by the management system 20 and the vehicle's main computer 50, respectively, thereby achieving safety redundancy. Similarly, the boost switch 16 is controllable by the main computer 50 and the control means 40.

[0063] In addition to the sensor 22, the charging system 32 also measures the common mode voltage V between the positive terminal of the charging socket 8 and the ground of the vehicle 30. + and a means for measuring the common mode voltage V between the negative terminal of the charging socket 8 and the ground of the vehicle 30. - A means for measuring

[0064] The vehicle's main computer 50 implements Method 1 using means or components of the charging system 32 to terminate charging and diagnose at least some of the power switches 13, 14, 15, 16.

[0065] An embodiment of the method 1 according to the invention will now be described with reference to Figure 2, immediately after the traction battery 2 has been recharged by the charging station 60 using the voltage boost stage 5. In this use example of the invention, for example, the maximum no-load voltage of the traction battery 2 is 800 V, whereas the charging station 60 cannot supply a voltage higher than 400 V. The charging current, which has just been completed, therefore flows in particular through the positive and negative DC switches 13 and 14, the boost switch 16, and the positive and negative battery switches 11 and 12, while the bypass switch 15 is not used and was kept open during charging.

[0066] Method 1 begins with an initial step 100 of completing a message exchange with charging station 60, thereby enabling confirmation that a request to open switches 62, 64 of charging station 60 has been received and approved, during which a charge termination protocol is performed that allows diagnostics to be performed on the power switches of vehicle 30. Thus, the voltage delivered from charging station 60 is theoretically zero during initial step 100 (unless there is a fault in charging station 60).

[0067] Note that during this first step 100, the positive and negative battery switches 11 and 12, as well as the boost switch 16, are closed.

[0068] The next step 110 controls the positive DC switch 13 and the negative DC switch 14 to an open state.

[0069] Method 1: After a few milliseconds, the voltage V DC The next step 120 is carried out, which is a first step of comparing the voltage S1 on the one hand with a predetermined safety voltage S1, here set to 60 V. Of course, as a variant, another predetermined safety voltage value is chosen, in particular depending on the current standards regarding electrical safety.

[0070] Method 1 compares in a first comparison step 120 the voltage V between the terminals of the charging socket 8 DC is lower than the predetermined safe voltage S1 (branch Y), Method 1 determines that at least one of the positive DC switch 13 and the negative DC switch 14 is not welded, and Method 1 proceeds to step 470 shown in FIG. 7 and described below (see elsewhere A). It should be noted that in this patent application, the comparison step uses strict or rough inequality conditions without changing the essence of the present invention. Therefore, the strict or rough nature of the inequality is not specified in this embodiment of the present invention.

[0071] Conversely, Method 1 compares in the first comparison step 120 the voltage V across the terminals of the charging socket 8DC is higher than the predetermined safety voltage S1 (branch N), after the first comparison step 120, on the other hand, the voltage V between the terminals of the charging socket 8 DC and on the other hand the voltage V across the terminals of the capacitor 6, called the boost voltage, measured by the charging system 32. B This is followed by a second comparison step 130 with

[0072] In the second comparison step 130, the voltage V between the terminals of the charging socket 8 is DC and boost voltage V B is greater than the predetermined voltage offset S2, which is equal to 30V in this embodiment of the present invention (branch Y), method 1 determines that at least one of the positive DC switch 13 and the negative DC switch 14 is not welded, and method 1 proceeds to step 470, shown in Figure 7 and described below. Of course, other values ​​for the predetermined voltage offset S2 may be selected, depending in particular on the use case of the charging system 32.

[0073] In the second comparison step 130, the voltage V between the terminals of the charging socket 8 is DC and boost voltage V B is determined to be less than a predetermined voltage offset S2 (branch N), and the charging lid closure sensor that allows access to the charging socket 8 is functional (branch Y of condition 135), the next step is step 170, which controls the positive battery switch 11 and the negative battery switch 12 to an open state, and then permission is given to disconnect the charging cable 70 if one of the following conditions is met: - voltage V between the terminals of 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 - is lower than the predetermined safety voltage S1, or - voltage V between the terminals of inverter 3 O is lower than the predetermined safe voltage S1. If one of these conditions is met, then the computer waits to receive a command to close the lid and then proceeds to step 240 shown in FIG. 4 and described below (see elsewhere B).

[0074] In the second comparison step 130, the voltage V between the terminals of the charging socket 8 is DC and boost voltage V B If the difference in absolute value between V and V is smaller than the predetermined voltage offset S2, and the vehicle computer 50 does not have information about the possibility of the charging cable 70 being disconnected (branch N of condition 135), for example, because the vehicle 30 is not equipped with a charging lid closure sensor or the sensor is faulty, the next step is to determine whether the boost voltage V B Step 140 involves discharging the capacitor 6 at the input of the voltage step-up stage 5 so that V reaches a predetermined voltage, for example 100 V. The computer 5 uses the control means 40 of the inverter 3 for this purpose.

[0075] After the discharge step 140, wait a few milliseconds and then measure the 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 follows with

[0076] In the third comparison step 150, the method 1 compares the voltage V between the terminals of the charging socket 8 DC is the boost voltage V B If it is determined that the positive DC switch 13 and the negative DC switch 14 are both welded (branch Y), Method 1 detects 160 that the positive DC switch 13 and the negative DC switch 14 are both welded; otherwise (branch N), Method 1 determines that at least one of the positive DC switch 13 and the negative DC switch 14 is not welded. If Method 1 determines that the positive DC switch 13 and the negative DC switch 14 are not welded, Method 1 proceeds to step 470 shown in FIG. 7 and described below.

[0077] It should be noted that if both the negative DC switch 14 and the positive DC switch 13 are diagnosed as welded, the positive battery switch 11 and the negative battery switch 12 are opened, and after verifying that the negative and positive battery switches are not welded, disconnection is permitted.

[0078] Assume now that computer 50 concludes at the end of method 1 in accordance with the present invention that positive DC switch 13 and negative DC switch 14 are not welded together, i.e., not stuck in the closed position. For example, this conclusion can be reached because at the end of first comparison step 120, the voltage across the terminals of charging socket 8 was less than predetermined safety voltage S1, and the method then determined (steps 490 and 545 described below with reference to FIG. 7 ) that the common-mode voltage at each of the terminals of charging socket 8 was also less than predetermined safety voltage S1.

[0079] Method 1 then performs the steps of FIG. 3, which are intended to determine the diagnostics of the boost switch 16.

[0080] The first step of this new diagnosis is to control the boost switch 16 to an open state 180. The initial open state control step 180 is followed by a step 190 of controlling the inverter 3 to discharge the capacitor 6, which is immediately followed by a step 191 of controlling the boost voltage V B is compared with a lower threshold S3 of the voltage of the capacitor 6, which is for example 60 V, or with the phase current I B the phase current I, which is a few amperes, say 5 amperes B The process continues to step 215 where the value of the positive integer sigma is compared with the lower threshold value S4.

[0081] Method 1 compares the boosted voltage V B After a few seconds, it is determined that the voltage of the capacitor 6 is lower than the lower threshold value S3, or the phase current I of the inverter 3 B For more than a few milliseconds, the phase current I BIf it is determined that the voltage difference is greater than the lower threshold S4 (step 220), this is because the capacitor 6 was able to discharge, and method 1 then determines in step 230 that the boost switch 16 is welded.

[0082] Conversely, Method 1 compares the boosted voltage V B After a few seconds, it is determined that the voltage of the capacitor 6 is still higher than the lower threshold S3, or the phase current I of the inverter 3 B remains near zero for several milliseconds 200, because capacitor 6 was not able to discharge, and Method 1 will then determine in step 210 that boost switch 16 is not welded.

[0083] 4 shows the steps following step 170 of controlling the positive battery switch 11 and the negative battery switch 12 to an open state and receiving an instruction by computer 50 to close the charging lid. This closure is performed by comparing the voltage V previously measured across the terminals of charging socket 8 in the first comparison step 120. DC is higher than the predetermined safe voltage S1, and the boost voltage V B and the voltage V between the terminals of the charging socket DC was less than a predetermined voltage offset S2. Therefore, a full diagnosis of the positive DC switch 13 and the negative DC switch 14 could not be performed. Note that the indication to close the charging lid may be inferred by the computer 50 from the vehicle 30 being driven above a certain speed threshold, for example, above 5 kilometers per hour.

[0084] In this configuration, the first step in diagnosing with the lid closed is to open the positive DC switch 13, the negative DC switch 14, and the bypass switch 15 if they are not already open, and close the positive battery switch 11 and the negative battery switch 12 if they are not already closed 240. For example, between the second comparison step 130 and the discharge step 140, the computer 50 may control the battery switches to the closed state if it detects that the vehicle is being driven between these two steps.

[0085] It should be noted that in this configuration, the computer 50 cannot distinguish whether the just-completed charge was a charge that used the voltage boost stage 5 or a charge that did not use the voltage boost stage 5; in other words, the computer 50 cannot distinguish whether it must diagnose the positive DC switch 13 and the negative DC switch 14, or whether it must diagnose the bypass switch 15 and the negative DC switch 14. Specifically, in this embodiment of the present invention, the type of charge that has just been performed is not stored in the memory of the computer 50.

[0086] After the control step 240, on the one hand, the voltage V between the terminals of the charging socket 8 DC and on the other hand with a lower differential voltage threshold S5, set at, for example, 60V, follows a fourth comparison step 250.

[0087] In a fourth comparison step 250, Method 1 compares the voltage V across the terminals of the charging socket 8. DC is higher than the differential voltage lower threshold S5 (branch N), this is because the two switches connected to the charging socket are welded together. In this case, the next step is to check the voltage V between the terminals of the charging socket 8. DC and a differential voltage intermediate threshold S6, which is set to 500 V here. DCis lower than the middle differential voltage threshold S6 and higher than the lower differential voltage threshold S5 260, because the just-completed charge used voltage boost stage 5, and method 1 determines 270 that positive DC switch 13 and negative DC switch 14 are welded. Conversely, if the method determines that the voltage V between the terminals of charging socket 8 is DC is between the middle differential voltage threshold S6 and the upper differential voltage threshold S7, e.g., 900V 280, because the charging that just completed did not use the voltage boost stage 5, Method 1 determines 290 that the bypass switch 15 and the negative DC switch 14 are welded.

[0088] In a fourth comparison step 250, Method 1 compares the voltage V across the terminals of the charging socket 8. DC is determined to be lower than the differential voltage lower limit threshold S5 (branch Y), this is because at least one of the two switches connected to the charging socket is welded.

[0089] In this case, after the fourth comparison step 250, on the one hand, the common mode voltage V + This is followed by a fifth comparison step 300 with the common mode voltage V at the positive terminal of the charging socket 8 and with a lower common mode voltage threshold S8, which is set to, for example, 60 V. + If the common mode voltage V at the positive terminal of the charging socket 8 is lower than the common mode voltage lower threshold S8 (branch Y), then method 1 determines that neither the bypass switch 15 nor the positive DC switch is welded 310. Conversely, if method 1 determines that the common mode voltage V at the positive terminal of the charging socket 8 is lower than the common mode voltage lower threshold S8 (branch Y), then method 1 determines that neither the bypass switch 15 nor the positive DC switch is welded 310. + is higher than the common mode voltage lower limit threshold S8 (branch N), the next step is to + and a common-mode voltage intermediate threshold S9, which is set to, for example, 500 V. Method 1 compares the voltage V between the terminals of the charging socket 8 DCis lower than the middle common-mode voltage threshold S9 and higher than the lower common-mode voltage threshold S8 320, because the just-completed charging used voltage boost stage 5, and method 1 determines that positive DC switch 13 and negative DC switch 14 are welded 330. Conversely, if the method determines that the voltage V between the terminals of charging socket 8 is DC is between the middle common mode voltage threshold S9 and the upper common mode voltage threshold S10, e.g., 900V 340, because the charging that just completed did not use the voltage boost stage 5, then Method 1 determines 350 that the bypass switch 15 and the negative DC switch 14 are welded.

[0090] Additionally, method 1 may determine at the end of the fourth comparison step 250 that at least one of the two switches connected to the charging socket is welded and the voltage V between the terminals of the charging socket 8 is DC is determined to be lower than the differential voltage lower threshold S5, after the fourth comparison step 250, on the other hand, the common mode voltage V - A sixth comparison step 360 follows, comparing the common mode voltage V at the negative terminal of the charging socket 8 with a low-level common mode voltage S11, set at, for example, 60 V, on the other hand. - is lower than the low-level common-mode voltage S11 (branch Y), method 1 determines that the negative DC switch 14 is not welded 370. Conversely, the common-mode voltage V - If is greater than the low-level common-mode voltage S11 (branch N), Method 1 determines 380 that the negative DC switch 14 is welded.

[0091] An embodiment of method 1 according to the invention will now be described with reference to FIG. 5, where the traction battery 2 has just been recharged by the charging station 60 without using the voltage boost stage 5. In this use case of the invention, the charging station 60 is capable of supplying a voltage equal to or greater than 800 V, which is the maximum no-load voltage of the traction battery 2. The charging current, which has just been completed, therefore flows in particular through the negative DC switch 14 and the bypass switch 15, as well as the positive battery switch 11 and the negative battery switch 12, but without using the boost switch 16, which was held open during charging. In this use case, the first steps of method 1 are essentially identical to those when the voltage boost stage 5 is used for charging, and will therefore be referred to in the same way, but showing differences with regard to the switches in question and some of the comparison voltages.

[0092] Method 1 begins with a first step 100, which is identical to the first step for charging using voltage boost stage 5. In particular, during this first step 100, positive battery switch 11 and negative battery switch 12 are closed.

[0093] The next step 110 controls the negative DC switch 14 and the bypass switch 15 to an open state.

[0094] This method detects, after a few milliseconds, the voltage V between the terminals of the charging socket 8. DC The next step 120 is carried out, which is a first comparison step between the voltage S1 and a predetermined safe voltage S2 on the other hand.

[0095] Method 1 compares in a first comparison step 120 the voltage V between the terminals of the charging socket 8 DC is determined to be lower than the predetermined safe voltage S1 (branch Y), method 1 determines that at least one of the bypass switch 15 and the negative DC switch 14 is not welded, and method 1 proceeds to step 470 shown in FIG. 7 and described below.

[0096] Conversely, in the first comparison step 120, Method 1 compares the voltage V DC is higher than the predetermined safety voltage S1 (branch N), after the first comparison step 120, on the other hand, the voltage V between the terminals of the charging socket 8 DC and on the other hand the voltage V measured across the terminals of the inverter 3 by the charging system 32, called the inverter voltage. O A second comparison step 130 follows with

[0097] In the second comparison step 130, the voltage V between the terminals of the charging socket 8 is DC and inverter voltage V O If it is determined that the difference in absolute value between the bypass switch 15 and the negative DC switch 14 is greater than the predetermined voltage offset S2 (branch Y), method 1 determines that at least one of the bypass switch 15 and the negative DC switch 14 is not welded, and method 1 proceeds to step 470 shown in FIG. 7 and described below.

[0098] In the second comparison step 130, the voltage V between the terminals of the charging socket 8 is DC and inverter voltage V O If it is determined that the difference in absolute value between the positive battery switch 11 and the negative battery switch 12 is smaller than the predetermined voltage offset S2 (branch N) and the charging lid closure sensor is functioning (branch Y of condition 135), the next step is step 170, which controls the positive battery switch 11 and the negative battery switch 12 to an open state, and then permission is given to disconnect the charging cable if one of the following conditions is met: - voltage V between the terminals of 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 - is lower than the predetermined safety voltage S1, or - Inverter voltage V O is lower than the predetermined safe voltage S1. If one of these conditions is met, the computer 50 waits to receive an instruction to close the door and then proceeds to step 240 shown in Figure 4, where step 240 and the following steps are the same as when the voltage boost stage 5 is used for charging.

[0099] In the second comparison step 130, the voltage V between the terminals of the charging socket 8 is DC and inverter voltage V O If the difference in absolute value between the voltages is determined to be less than the predetermined voltage offset S2 and the vehicle computer 50 does not have information about the possibility of the charging cable being disconnected (branch N of condition 135), for example, because the vehicle is not equipped with a charging lid closure sensor or the sensor is faulty, method 1 proceeds to the steps shown in Figure 6 (see elsewhere C). These steps are as follows: - Control the positive battery switch 13 and the negative battery switch 14 to the open state 390, and then after a few seconds, - voltage V between the terminals of charging socket 8 DC is further compared with a predetermined safe voltage S1, and the voltage V between the terminals of the charging socket 8 is DC is lower than the predetermined safety voltage S1 (branch Y), - Control the positive battery switch 13 and the negative battery switch 14 to the closed state 410, and then - voltage V between the terminals of charging socket 8 DC is further compared 420 with a predetermined safe voltage S1, and method 1 determines whether the voltage V between the terminals of the charging socket 8 is DC is determined to be higher than the predetermined safe voltage S1 (branch N), method 1 detects 430 that the negative DC switch 14 is welded and the bypass switch 15 is welded. In this case, the positive battery switch 11 and the negative battery switch 12 are opened, and after verifying that the positive battery switch and the negative battery switch are not welded, disconnection is allowed.

[0100] Conversely, method 1 compares in a further comparison step 420 the voltage V across the terminals of the charging socket 8 DCis determined to be lower than the predetermined safe voltage S1 (branch Y), method 1 determines that at least one of the bypass switch 15 and the negative DC switch 14 is not welded, and method 1 proceeds to step 470 shown in FIG. 7 and described below.

[0101] During a further comparison step 400, the voltage V between the terminals of the charging socket 8 DC is higher than the predetermined safety voltage S1 (branch N), after this further comparison step 400, the inverter voltage V O This is followed by a comparison step 440 of the inverter voltage V with a predetermined safe voltage S1. O is lower than the predetermined safe voltage S1 (branch Y), the user is allowed to disconnect the charging cable 70, method 1 determines 450 that at least one of the bypass switch 15 and the negative DC switch 14 is not welded, and method 1 proceeds to step 470 shown in FIG. O is higher than the predetermined safe voltage S1 (branch N), method 1 prevents 460 the user from disconnecting charging cable 70 and loops back to further comparison step 400. Specifically, in this case, a dangerous voltage persists across the terminals of charging socket 8 and across the terminals of the inverter, which may be the result of simultaneous welding of switches 62, 64 and negative DC switch 14 and bypass switch 15 of charging station 60, switches 62, 64 and positive battery switch 11 and negative battery switch 12 of charging station 60, or even negative DC switch 14 and bypass switch 15 and positive battery switch 11 and negative battery switch 12. The user must then press the emergency button on charging station 60 to reduce the voltage delivered by the charging station and allow charging socket 8 to be disconnected.

[0102] Finally, in one of the cases mentioned above with respect to FIG. 2, FIG. 5, or FIG. 6, if Method 1 determines that the voltage boost stage 5 is not being used for charging and at least one of the bypass switch 15 and the negative DC switch 14 is not welded, or if Method 1 determines that the voltage boost stage 5 is not being used for charging and at least one of the negative DC switch 14 and the positive DC switch 13 is not welded, - The user is allowed to disconnect the charging cable, Method 1 proceeds to step 470 of FIG. 7, in which the bypass switch 15 and the positive DC switch 13 and the negative DC switch 14, which are not already controlled to an open state, are controlled to an open state.

[0103] During this open control step 470, the positive battery switch 11 and the negative battery switch 12 remain closed.

[0104] The open control step 470 is then followed by two comparison steps, which may be performed in parallel and / or in sequence, and these steps are as follows: - On the other hand, the common mode voltage V at the negative terminal of charging socket 8 - a seventh comparison step 480 of the first common mode voltage lower limit S12, for example 60V, on the other hand; and - On the other hand, the common mode voltage V of the positive terminal of charging socket 8 + and on the other hand with a second common mode voltage lower limit S13, for example 60V, in an eighth comparison step 540.

[0105] In a seventh comparison step 480, Method 1 compares the common mode voltage V - is lower than the first common-mode voltage lower limit S12 (branch Y), method 1 determines 490 that the negative DC switch is not welded. Similarly, in an eighth comparison step 540, method 1 determines that the common-mode voltage V +is determined to be lower than the second common-mode voltage lower limit S13 (branch Y), method 1 determines 545 that the positive DC switch 13 is not welded when the voltage boost stage 5 is used for charging, or that the bypass switch 15 is not welded when the voltage boost stage 5 is not used for charging.

[0106] Conversely, in the seventh comparison step 480, Method 1 compares the common mode voltage V - is determined to be higher than the first common-mode voltage lower limit S12 (branch N), the seventh comparison step 480 is followed by step 500 of controlling the positive DC switch to a closed state if the voltage boost stage 5 is used for charging, or controlling the bypass switch 15 to a closed state if the voltage boost stage 5 is not used for charging.

[0107] After step 500 of controlling to the closed state, after a few milliseconds, if Method 1 uses a voltage boost stage for charging, on the other hand, the boost voltage V B On the other hand, the voltage V between the terminals of the charging socket 8 DC This is followed by a ninth comparison step 510 in which the boosted voltage V B is the voltage V between the terminals of the charging socket 8 DC (branch Y), method 1 determines that the negative DC switch 14 is welded 520; otherwise (branch N), method 1 determines that the negative DC switch 14 is not welded 530. If the voltage boost stage was not used for charging, in the ninth comparison step 510, method 1 determines that the inverter voltage V O On the other hand, the voltage V between the terminals of the charging socket 8 DC Compared with the inverter voltage V O is the voltage V between the terminals of the charging socket 8 DC If it is equal to (branch Y), method 1 determines 520 that the negative DC switch 14 is welded; otherwise (branch N), method 1 determines 530 that the negative DC switch 14 is not welded.

[0108] Similarly, in an eighth comparison step 540, Method 1 compares the common mode voltage V+ is higher than the second common-mode voltage lower limit S13 (branch N), the eighth comparison step 540 is followed by a step 550 of controlling the negative DC switch to a closed state.

[0109] After step 550 of controlling to the closed state, after a few milliseconds, if Method 1 uses a voltage boost stage for charging, on the other hand, the boost voltage V B On the other hand, the voltage V between the terminals of the charging socket 8 DC This is followed by a tenth comparison step 560 in which the boosted voltage V B is the voltage V between the terminals of the charging socket 8 DC (branch Y), method 1 determines that the positive DC switch 13 is welded 570, otherwise (branch N), method 1 determines that the negative DC switch 13 is not welded 580. If the voltage boost stage 5 was not used for charging, in the tenth comparison step 560, method 1 determines that the inverter voltage V O On the other hand, the voltage V between the terminals of the charging socket 8 DC Compared with the inverter voltage V O is the voltage V between the terminals of the charging socket 8 DC If (branch Y), method 1 determines 570 that the bypass switch 15 is welded; otherwise (branch N), method 1 determines 580 that the bypass switch 15 is not welded.

[0110] The invention is of course not limited to the examples that have just been described, and many modifications may 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 or hybrid vehicle (30) and diagnosing a power switch (13, 14, 15, 16), the method comprising: the vehicle (30) including a traction battery (2) and an inverter (3) capable of supplying power to an electric motor (4) of the vehicle (30); and the charging system (32) including at least: a switch (11) called positive battery switch, connected with a first terminal to the positive terminal of said traction battery (2) and with a second terminal to the positive input terminal of said inverter (3); a switch (12) called negative battery switch, connected with a first terminal to the negative terminal of said traction battery (2) and with a second terminal to the negative input terminal of said inverter (3); a voltage boost stage (5) comprising at least one capacitor (6), the positive terminal of which is connected to the positive input terminal of said voltage boost stage (5) and the negative terminal of which is connected to the negative input terminal of said voltage boost stage (5); two switches (13, 14, 15) used during charging, called switches under test, the first switch under test (13, 15) being connected with a first terminal to the positive terminal of the charging socket (8) and with a second terminal to the positive input terminal of the voltage boost stage (5) when the voltage boost stage (5) is used for the charging, and the second switch under test (14) being connected with a first terminal to the negative terminal of the charging socket (8) and with a second terminal to the second terminal of the negative battery switch (12); wherein the method (1) comprises: - controlling (110) the switches under test (13, 14, 15) in an open state; - on the other hand, the voltage between the terminals of the charging socket (8) (V ＤＣ a first comparison step (120) of the voltage (V) with a predetermined safety voltage (S1) on the other hand, and the method (1) comprises: ＤＣ ) is higher than the predetermined safe voltage (S1), - on the other hand, the voltage (V ＤＣ a second comparison step (130) of the voltage across the second terminals of the switches under test (13, 14, 15) on the other hand; further comprising If the method (1) uses the voltage boost stage (5) for the charging, and the difference between the voltages compared in the second comparison step (130) is less than a predetermined voltage offset (S2), and there is no information about the closure of a charging lid of the vehicle (30) used to access the charging socket (8), the method (1) adds a step (140) of discharging the capacitor (6), and then, meanwhile, increasing the voltage (V) between the terminals of the charging socket (8). ＤＣ ) on the other hand, the voltage (V) between the second terminals of the test switch (13, 14). Ｂ ) a third comparison step (150) with the

2. The motor (4) and the inverter (3) form part of the voltage boost stage (5), the voltage boost stage (5) comprising a switch (16), called a boost switch, connected at a first terminal to the positive terminal of the capacitor (6) and at a second terminal to the neutral point of the motor (4), the method (1) using the voltage boost stage (5) for charging, and the method (1) not diagnosing a welding of the test switch (13, 14), the method (1) - controlling (180) said boost switch (16) in an open state; - controlling (190) said inverter (3) to discharge said capacitor (6); - the voltage across the terminals of the capacitor (6) (V Ｂ ) or the phase current of the inverter (3), respectively, by adjusting the lower threshold (S3) of the voltage of the capacitor (6) or the phase current (I Ｂ ) with a lower threshold (S4), and the voltage (V) across the terminals of the capacitor (6) is compared (215). Ｂ ) is lower than the lower threshold (S3) of the voltage of the capacitor (6), or the phase current (I Ｂ ) is the phase current (I Ｂ ) is greater than the lower threshold value (S4), detecting that the boost switch (16) is welded (230); 2. The method (1) for charging termination and diagnosis according to claim 1, characterized in that it comprises:

3. The charging system (32) a switch (13), called positive DC switch, connected with a first terminal to the positive terminal of the charging socket (8) and with a second terminal to the positive input terminal of the voltage step-up stage (5); a switch (14), called negative DC switch, connected with a first terminal to the negative terminal of the charging socket (8) and with a second terminal to the negative input terminal of the voltage step-up stage (5); and when the switch under test uses the voltage boost stage (5) for charging, the positive DC switch (13) and the negative DC switch (14) are the voltage (V Ｂ 3. The method (1) for terminating and diagnosing a charge according to claim 1 or 2, wherein the voltage is called boost voltage in this case.

4. The charging system (32) includes a switch (15), called a bypass switch, connected at a first terminal to the first terminal of the positive DC switch (13) and at a second terminal to the second terminal of the positive battery switch (11), and when the test switch does not use the voltage boost stage (5) for charging, the test switch (15) is the negative DC switch (14) and the bypass switch (15), and the voltage (V) between the second terminals of the test switches (14, 15) is Ｏ 4. The method (1) for charge termination and diagnosis according to claim 3, wherein the voltage Vcc is referred to as inverter voltage in this case.

5. If the closure of the charging lid is detected (135), after the second comparison step, regardless of whether the voltage boost stage (5) was used for charging or not, the bypass switch (15), the positive DC switch (13) and the negative DC switch (14) are controlled to an open state (240), and the positive battery switch (11) and the negative battery switch (12) are controlled to a closed state (240), while the voltage (V) between the terminals of the charging socket (8) is ＤＣ ) on the other hand with at least one differential voltage threshold value of a lower differential voltage threshold value (S5) and a middle differential voltage threshold value (S6), so that the voltage (V ＤＣ If the voltage (V) between the terminals of the charging socket (8) is greater than the differential voltage intermediate threshold (S6), the bypass switch (15) and the negative DC switch (14) are detected to be welded (290), or the voltage (V) between the terminals of the charging socket (8) is detected to be welded (290). ＤＣ 5. The method (1) for charge termination and diagnosis of claim 4, wherein welding of the positive DC switch (13) and the negative DC switch (14) is detected (270) when the differential voltage lower threshold (S5) and the differential voltage middle threshold (S6) are between the differential voltage lower threshold (S5) and the differential voltage middle threshold (S6).

6. The fourth comparing step (250) compares the voltage (V ＤＣ ) is lower than the differential voltage lower threshold (S5), after the fourth comparison step (250), on the other hand, ＋ ) on the other hand with at least one common mode voltage threshold of a lower common mode voltage threshold (S8) and a middle common mode voltage threshold (S9), so that the common mode voltage (V ＋ If the common mode voltage (V) is lower than the common mode voltage lower threshold (S8), it is concluded that the bypass switch (15) and the positive DC switch (13) are not welded (310), or the common mode voltage (V) of the positive terminal of the charging socket (8) is ＋ If the common mode voltage (V) is between the lower common mode voltage threshold (S8) and the middle common mode voltage threshold (S9), it is concluded that the positive DC switch (13) is welded (330), or the common mode voltage (V) at the positive terminal of the charging socket (8) is low. ＋ 10. The method (1) for charge termination and diagnosis of claim 5, wherein if the common mode voltage intermediate threshold (S9) is greater than the common mode voltage intermediate threshold (S9), a conclusion is made (350) that the bypass switch (15) is welded.

7. The fourth comparing step (250) compares the voltage (V ＤＣ ) is lower than the differential voltage lower limit threshold (S5), after the fourth comparison step (250), on the other hand, － A sixth comparison step (360) follows between the negative terminal of the charging socket (8) and the low-level common mode voltage (V － 7. The method (1) for charge termination and diagnosis according to claim 5 or 6, wherein if the negative DC switch (14) is not welded (370), then a conclusion is made that the negative DC switch (14) is not welded (380), otherwise a conclusion is made that the negative DC switch (14) is welded.

8. If the voltage boost stage (5) is not used for charging, the difference between the voltages compared in the second comparison step (130) is less than a predetermined voltage offset (S2), and there is no information about the closure of a charging lid of the vehicle (30) used to access the charging socket (8), the method (1) - controlling (390) said positive battery switch (13) and said negative battery switch (14) in an open state; - the voltage (V) between the terminals of the charging socket (8) ＤＣ ) with the predetermined safe voltage (S1), and ＤＣ ) is lower than the predetermined safe voltage (S1), - controlling (410) the positive battery switch (13) and the negative battery switch (14) in a closed state; - the voltage (V) between the terminals of the charging socket (8) ＤＣ ) with the predetermined safe voltage (S1), and ＤＣ 8. The method (1) for terminating and diagnosing charging according to claim 4, further comprising the step of detecting (430) whether the negative DC switch (14) and the bypass switch (15) are welded if the voltage (S1) is greater than the predetermined safe voltage (S1), and otherwise proceeding to the step of concluding that at least one of the bypass switch (15) and the negative DC switch (14) is not welded.

9. The voltage (V ＤＣ ) with the predetermined safe voltage (S1), the voltage (V ＤＣ ) is higher than the predetermined safe voltage (S1), the method - the inverter voltage (V Ｏ ) with the predetermined safe voltage (S1), so that the inverter voltage (V Ｏ 9. The method (1) for charging termination and diagnosis as set forth in claim 8, wherein if the voltage (S1) is lower than the predetermined safe voltage (S1), a conclusion is made that at least one of the bypass switch (15) and the negative DC switch (14) is not welded, otherwise, disconnection of the charging cable (70) to which the charging socket (8) is connected is prevented (460), and the step of preventing disconnection loops back to the further comparing step (400).

10. The third comparing step (150) compares the voltage (V ＤＣ ) is the boosted voltage (V Ｂ 10. The method (1) for terminating and diagnosing charging according to claim 3, wherein if it determines that the positive and negative DC switches (13, 14) are equal to each other, the method (1) detects (160) that the positive and negative DC switches (13, 14) are welded, and if not, the method (1) determines that at least one of the positive and negative DC switches (13, 14) is not welded.

11. The voltage boost stage (5) is used for charging, and the first comparison step (120) compares the voltage (V ＤＣ ) is lower than the predetermined safe voltage (S1), or the second comparison step (130) determines that the boosted voltage (V Ｂ ) and the voltage (V ＤＣ 11. The method (1) for terminating and diagnosing charging according to claim 3, wherein 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 difference between the positive DC switch (13) and the negative DC switch (14) is determined to be greater than the predetermined voltage offset (S2).

12. The charging does not use the voltage boost stage (5) and the first comparison step (120) compares the voltage (V ＤＣ ) is lower than the predetermined safe voltage (S1), or the second comparison step (130) determines that the voltage (V Ｏ ) and the voltage (V ＤＣ 12. The method (1) for terminating and diagnosing charging according to claim 4, wherein the method (1) determines that at least one of the bypass switch (15) and the negative DC switch (14) is not welded when the method (1) determines that the difference between the negative DC switch (14) and the bypass switch (15) is greater than the predetermined voltage offset (S2).

13. When the method (1) determines that the voltage boost stage (5) is used for the charging and at least one of the positive pole DC switch (13) and the negative pole DC switch (14) is not welded, or when the voltage boost stage (5) is not used for the charging and at least one of the bypass switch (15) and the negative pole DC switch (14) is not welded, the method (1) controls (470) the negative pole DC switch (14) on the one hand and the positive pole DC switch (13) or the bypass switch (15) on the other hand to an open state, and controls (471) the common mode voltage (V) of the negative pole terminal of the charging socket (8) on the other hand. － ) on the other hand with a first common mode voltage lower limit (S12), so that the common mode voltage (V － If the common mode voltage (V) of the positive terminal of the charging socket (8) is lower than the first common mode voltage lower limit (S12), it is concluded that the negative DC switch (14) is not welded (490), while the common mode voltage (V) of the positive terminal of the charging socket (8) is lower than the first common mode voltage lower limit (S12). ＋ ) on the other hand with a second common mode voltage lower limit (S13), so that the common mode voltage (V ＋ ) is lower than the second common-mode voltage lower limit (S13), a conclusion is reached (545) that the positive DC switch (13) or the bypass switch (15) is not welded.

14. The common mode voltage (V － ) is higher than the first voltage lower limit value (S12), the method (1) controls the positive DC switch (13) or the bypass switch (15) to a closed state (500), and then, on the other hand, controls the boost voltage (V Ｂ ) or the inverter voltage (V Ｏ ) and on the other hand the voltage (V ＤＣ ) and proceeds to a ninth comparison step (510) with the boosted voltage (V Ｂ ) or the inverter voltage (V Ｏ ) is the voltage (V ＤＣ ) then detecting (520) that the negative DC switch (14) is welded; otherwise, concluding (530) that the negative DC switch (14) is not welded.

15. The common mode voltage (V ＋ ) is higher than the second lower voltage limit (S13), the method (1) controls the negative DC switch (14) to a closed state (550), and then, on the other hand, controls the boost voltage (V Ｂ ) or the inverter voltage (V Ｏ ) and on the other hand the voltage (V ＤＣ ), and proceeds to a tenth comparison step (560) with the boosted voltage (V Ｂ ) or the inverter voltage (V Ｏ ) is the voltage (V ＤＣ ), detecting (570) that the positive DC switch (13) or the bypass switch (15) is welded; otherwise, concluding (580) that the positive DC switch (13) or the bypass switch (15) is not welded.

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