CN120615065A

CN120615065A - Method for terminating charging of a charging system for an electric vehicle or a hybrid vehicle and diagnosing switches of the charging system

Info

Publication number: CN120615065A
Application number: CN202380091488.0A
Authority: CN
Inventors: A·德比卜; S·拉瓦里
Original assignee: Ampere Corp
Current assignee: Ampere Corp
Priority date: 2022-12-16
Filing date: 2023-12-01
Publication date: 2025-09-09
Also published as: EP4633991A1; FR3143460A1; KR20250126080A; WO2024126102A1; JP2025541876A

Abstract

The invention relates to a method for ending the 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 boost stage (5) with a capacitor (6) connected at its input terminals, and two switches (13, 14) each connected to a separate terminal of a charging socket (8), the method comprising a command for switching off 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, when the load has used the boost stage (5) and in the absence of information about the closing of the charging 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

Method for ending the charging of a charging system of an electric or hybrid vehicle and for diagnosing a switch of the charging system

Technical Field

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

Background

Electric or hybrid vehicles typically include a high voltage traction battery that powers an electric traction motor of the vehicle with AC via an inverter. Therefore, the vehicle needs a system for charging the traction battery. Such systems recharge the traction battery by harvesting energy while the vehicle is braked or by drawing energy from a charging station external to the vehicle. DC charging stations in particular allow for very rapid charging of traction batteries by delivering a charging voltage greater than the voltage of the traction battery, which is on the order of a few hundred volts.

To allow such fast charging, the charging system must include a power switch that allows the traction battery to be electrically connected to the DC charging station. The very high currents delivered by such charging stations (which may reach hundreds of amperes) may damage the switches. In particular, if the switches are mechanical relays, passing an excessively high amplitude current through the switches may cause the switches to weld to their terminals, making the switches impossible to turn off. In the case of MOSFETs (MOSFETs are acronyms for metal oxide semiconductor field effect transistors), passing too high an amplitude of current through the switches may also damage the substrate of the switches, making the switches likewise impossible to turn off. In both cases, the power switch is considered to be "fused". In particular, in this patent application, the term "fused" is 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 such an extent that it is impossible to turn off.

In order to ensure the electrical safety of the user of the vehicle at the start or end of the charging and in order to prevent subsequent malfunctions of the vehicle due to such damage to the power switches, it is usual for the computer of the vehicle to be able to diagnose the power switches located between the charging socket of the vehicle and the traction battery of the vehicle, these power switches being located upstream of the power switches connecting the traction battery of the vehicle to the inverter. To perform this diagnosis, the vehicle will communicate with the charging station. When the charging station receives an indication that the vehicle has started such a diagnostic process, the charging station must turn its own power switch off, i.e., reduce its charging voltage to zero and not deliver any charging current to the vehicle.

Furthermore, some vehicles now comprise a traction battery with a maximum no-load voltage that is much greater than the maximum available voltage level output by conventional charging stations delivering a maximum voltage of less than 500V (volts), and therefore in such vehicles the charging socket for DC charging is no longer directly connected to the traction battery of the vehicle, but to the input of a boost stage, the output of which is connected to the traction battery.

In this case, at least some of these power switches that the vehicle must diagnose are located between the charging outlet of the vehicle and the input of the boost stage, always upstream of the inverter.

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

Due to the position 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:

On the one hand, due to the problems caused by both the welding of the power switch of the charging station and the welding of the power switch connecting the traction battery of the vehicle to its inverter, the voltage level of this battery is substantially the same as the voltage level delivered by the charging station,

And on the other hand problems only due to welding of the power switch to be diagnosed.

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

Therefore, it is necessary to ensure the safety of the user of the electric vehicle or hybrid vehicle by correctly diagnosing the normal operation or failure of the power switches located downstream of the charging socket of the vehicle and upstream of the power switches connecting the traction battery of the vehicle to the inverter of the vehicle, these switches possibly being located upstream of the input of the boost stage of the vehicle, depending on the configuration of the charging system of the vehicle.

Disclosure of Invention

The present invention aims to at least partially remedy the drawbacks of the prior art by providing a method for terminating the charging of a charging system of an electric vehicle or hybrid vehicle equipped with a step-up stage and diagnosing the power switch of the charging system, which makes it possible to obtain a welding diagnosis for each of these switches for charging the battery of the vehicle via the step-up stage by using the step-up stage skillfully, and which makes it possible to improve the electrical safety of the user.

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

A switch, called positive battery switch, connected by a first one of its terminals to the positive terminal of the traction battery and by a second one of its terminals to the positive input terminal of the inverter, and

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

A boost stage comprising at least one capacitor, the positive terminal of the at least one capacitor being connected to the positive input terminal of the boost stage, and the negative terminal of the at least one capacitor being connected to the negative input terminal of the boost stage,

Two switches used during charging, called to-be-tested switches, a first to-be-tested switch being connected by a first one of its terminals to the positive terminal of the charging socket and by a second one of its terminals to the positive input terminal of the boost stage, a second to-be-tested switch being connected by a first one of its terminals to the negative terminal of the charging socket and by a second one of its terminals to the second terminal of the negative battery switch when the boost stage is used by the charging,

The method comprises the following steps:

a step of controlling the opening of these switches to be tested,

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,

The method further includes when the voltage between the terminals of the charging jack is greater than the predefined safety voltage:

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

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 smaller than a predefined voltage offset, and in the absence of information about the closing of the charging flap of the vehicle for approaching the charging socket, the method additionally comprises a step of discharging the capacitor, and then a third comparison step of comparing the voltage between the terminals of the charging socket on the one hand with the voltage between the second terminals of the switches to be tested on the other hand.

It should be noted that the voltages compared in this method according to the invention are positive voltages or absolute voltage values, unless otherwise indicated. In addition, the steps of the method are referred to in the order in which they are performed. These steps are at least partially carried out by the computer of the vehicle at the end of a DC charge of the traction battery, the charge using a charging socket of the vehicle, the charging socket being connected to the DC charging station via a charging cable.

It should also be noted that the connections described in this patent application with respect to the terminals of the switch are direct connections, i.e. connections with components having only a zero resistance or almost zero resistance of the conductive function, 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 mutually different terminals of the switch.

In addition, in this patent application, unless otherwise indicated, a connection to an input or output of a functional component (such as an inverter or a boost stage) is understood to be a connection to a terminal of that input or output, respectively, i.e. a parallel connection to that input or output, respectively. The output of the inverter is here connected (with respect to its inverter function) in particular to the connection points of the motor of the vehicle.

Also in this patent application, a traction battery is understood to be a battery that powers the inverter and the motor when the vehicle is driven, in contrast to the auxiliary battery of the vehicle that powers the vehicle's low-voltage network (e.g. 14V) to which various consumers, including the vehicle's main computer, are connected. Thus, depending on the motor used, the traction battery may also be understood as a propulsion battery. Unless otherwise indicated, the batteries referred to in this patent application are traction batteries of a vehicle. Similarly, in this patent application, the terms "motor" and "inverter" refer to an electric traction or propulsion motor and to a traction or propulsion inverter of a vehicle, without any opposite indication. Finally, the terms "charging" and "recharging" are considered equivalent in this patent application.

In a third comparison step of the method according to the invention, the charging uses 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 terminal of the traction battery. In this patent application, "using a boost stage" means that the charging current flows through the boost stage, which is systematically the case if the charging system has no means of direct connection between the charging station and the traction battery.

By discharging the capacitor prior to the third comparison step, the voltage between the terminals of the charging socket during the third comparison step must be different from the voltage between the second terminals of the switches to be tested (if these switches to be tested are not all welded). In the opposite case, the switch to be tested is diagnosed as welded, which is not possible in the prior art, since the voltage between the terminals of the capacitor is in any case substantially equal to the charging voltage, which makes it impossible to exclude welding of the switch of the charging station.

The third step is performed if the vehicle's computer does not have information about whether the user will be exposed to dangerous voltages of the vehicle when the charging cable is not connected (e.g., if the vehicle does not have a sensor with the charging flap closed, or if the sensor is faulty). Therefore, the diagnosis performed after the third comparison step allows the user to completely and safely disconnect the charging cable only when at least one of the two switches to be tested is not diagnosed as welded.

By means of the invention, a more thorough diagnosis of the switch used during charging with the boost stage is thus possible, and this allows the user to disconnect the charging cable without risking electric shock.

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

-controlling the boost switch to be turned off,

Controlling the inverter to discharge the capacitor,

-Comparing the voltage between the terminals of the capacitor or the phase current of the inverter with a low threshold value of the voltage of the capacitor or the phase current, respectively, and detecting a welding of the boost switch if the voltage between the terminals of the capacitor is smaller than the low threshold value of the voltage of the capacitor or if the phase current of the inverter is larger than the low threshold value of the phase current. In the opposite case, the method determines that the boost switch is not welded if the voltage between the terminals of the capacitor is greater than a low threshold of the voltage of the capacitor, or if the phase current of the inverter is zero for a period of time immediately after a discharge command.

The motor of the charging system is an AC motor, such as a three-phase motor. In this way, which implements the invention, the stator inductances of the three-phase motor are used as current storage inductances in the boost stage, which are discharged into the traction battery by the inverter during the switching duty cycle of the switches of the inverter, which duty cycle is set in particular as a function of the voltage or current measurements made by the charging system. By reusing components for vehicle traction to form the boost stage, space in the engine compartment is saved, and the cost of using specific components to create the stage is saved.

Diagnosis of the boost switch makes it possible to ensure proper operation of the vehicle after charging using the boost switch. In particular, when the switch is welded, the parallel capacitor of the motor and the inverter may degrade the operation of the vehicle while traveling.

The charging system comprises in particular:

a switch, called positive DC switch, connected by a first one of its terminals to the positive terminal of the charging socket and by a second one of its terminals to the positive input terminal of the boost stage, and

A switch, called negative DC switch, connected by a first one of its terminals to the negative terminal of the charging socket and by a second one of its terminals to the negative input terminal of the boost stage,

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 referred to as the boost voltage, which also corresponds to the voltage between the terminals of the capacitor.

In one embodiment of the invention, the charging system comprises a switch, called a bypass switch, connected by a first one of its terminals to a first terminal of the positive DC switch and by a second one of its terminals to a second terminal of the positive battery switch,

When the boost stage is not used by the charge, 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 then being referred to as the inverter voltage.

In this embodiment of the invention, the charging system comprises means for directly connecting the charging station to the traction battery (i.e. the means does not pass through the step-up stage), i.e. only a few zero-resistance or almost zero-resistance conductors or components (such as battery switches) which, when these direct connection means are used, separate the charging socket from the traction battery.

These direct connection means are advantageously used when the vehicle is connected to a charging station which 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, the charging current does not experience electrical losses in the boost stage. This additionally avoids the need to oversubscribe the vehicle's motor and inverter to allow them to withstand the charging current delivered by such a charging station.

This embodiment optimizes the number of switches comprising such a directly connected charging system according to the invention, since the negative DC switch is used both for charging the traction battery with the boost stage and for charging the battery without the boost stage. This embodiment of the direct connection device does not require that the positive DC relay be closed during charging of the traction battery without employing a boost stage. In addition, 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 may adversely affect the charging or charging system during charging of the traction battery without using the boost stage.

The invention is thus applicable to a charging system that uses a boost stage to charge at least a traction battery when the charging voltage delivered by a charging station is less than the maximum no-load voltage of the battery, and that may also include devices directly connected to the battery, in which case these direct connection devices are used when the charging voltage delivered by the charging station is greater than the maximum no-load voltage of the battery.

According to an advantageous feature of the method according to the present invention, in case the charging system comprises means directly connected to the battery, when it has been detected that the charging flip-flop is closed, irrespective of whether the charging uses the boost stage, a fourth comparison step of comparing the voltage between the terminals of the charging socket on the one hand with at least one of a low differential voltage threshold and an intermediate differential voltage threshold on the other hand is performed after the second comparison step, whereby a 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, or a 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 and the intermediate differential voltage threshold, is controlled to be open.

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 comparing the common mode voltage of the positive terminal of the charging socket on the one hand with at least one of a low common mode voltage threshold and an intermediate common mode voltage threshold on the other hand, whereby it is concluded that the bypass switch and the positive DC switch have not been welded when the common mode voltage of the positive terminal of the charging socket is less than the low common mode voltage threshold, or that the positive DC switch has been welded 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, or that the bypass switch has been welded if the common mode voltage of the positive terminal of the charging socket is greater than the intermediate common mode voltage threshold.

It is also advantageous that, when the fourth comparison step determines that the voltage between the terminals of the charging socket is less than the low differential voltage threshold, then a sixth comparison step is performed after the fourth comparison step comparing the common mode voltage of the negative terminals of the charging socket on the one hand with a low common mode voltage level on the other hand, leading to the conclusion that the negative DC switch has not been welded when the common mode voltage of the negative terminals of the charging socket is less than the low common mode voltage level, otherwise the negative DC switch has been welded. The fifth comparison step and the sixth comparison step are for example performed in parallel after the fourth comparison step.

The various differential or common mode voltage thresholds allow for diagnosing the welding of the bypass switch to one of the positive and negative DC switches, although the two switches for charging are a priori unknown in case the user has disconnected the plug from the socket.

In another use case of the method according to the invention, when the boost stage is not used by the charge, when the difference between the voltages compared in the second comparison step is smaller than a predefined voltage offset, and in the absence of information about the closing of the charging flap of the vehicle for approaching the charging socket, the method proceeds with the following steps:

Control the positive battery switch and the negative battery switch to be opened,

-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:

controlling the positive battery switch and the negative battery switch to be closed,

-Additionally comparing the voltage between the terminals of the charging socket with the predefined safety voltage and detecting a 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.

Therefore, in this use case, the method according to the present invention skillfully uses the voltage differences measured according to the states of the positive and negative battery switches to perform diagnosis of the negative DC switch and the bypass switch.

In this further use case of the method according to the invention, during an 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 proceeds with the following steps:

-comparing the inverter voltage with the predefined safety voltage, thereby concluding that at least one of the bypass switch and the negative DC switch is not welded when the inverter voltage is smaller than the predefined safety voltage, otherwise preventing disconnection of a charging cable connected to the charging socket, the step being cycled back to the additional comparing step.

Thus, the present invention minimizes the situation where the user is not allowed to disconnect the charging plug from the receptacle.

Returning to a more general use case of the invention, based on another advantageous feature of the method according to the invention, when the third comparison step determines that the voltage between the terminals of the charging socket is equal to the boost voltage, then the method detects welding of the positive DC switch and the negative DC switch, 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 level of the compared voltages, in the present patent application, equality between the voltages is evaluated to be within a tolerance of a few volts.

Further, advantageously, in the method according to the invention, when the charging uses the boost stage, and when the first comparing step determines that the voltage between the terminals of the charging socket is less than the predefined safety voltage, or when the second comparing 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, then the method determines that at least one of the positive DC switch and the negative DC switch is not welded.

Similarly, when the charging does not use the boost stage, and when the first comparing step determines that the voltage between the terminals of the charging socket is less than the predefined safe voltage, or when the second comparing 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, then the method determines that at least one of the bypass switch and the negative DC switch is not welded.

It is also advantageous when the method according to the invention determines that at least one of the positive and negative DC switches is not welded in case the charging uses the boost stage or that at least one of the bypass switch and the negative DC switch is not welded in case the charging does not use the boost stage, the method continues with a seventh comparison step of comparing the common mode voltage of the negative terminal of the charging socket on the one hand with a first low common mode voltage limit on the other hand, if the negative DC switch and the positive or bypass switch, respectively, are controlled to open, whereby it is concluded that the negative DC switch is not welded when the common mode voltage of the negative terminal of the charging socket is less than the first low common mode voltage limit, and that the method continues with an eighth comparison step of comparing the common mode voltage of the positive terminal of the charging socket on the one hand with a second low common mode voltage limit on the other hand, whereby it is concluded that the positive DC switch or the bypass switch, respectively, is not welded when the common mode voltage of the positive terminal of the charging socket is less than the second low common mode voltage limit.

The seventh comparison step and the eighth comparison step are for example performed in parallel.

Advantageously, during the seventh comparison step, when the common mode voltage of the negative terminal of the charging socket is greater than the first low voltage limit, the method according to the invention continues with a ninth comparison step of comparing the boost voltage or the inverter voltage, respectively, with the voltage between the terminals of the charging socket, respectively, after the positive DC switch or the bypass switch, respectively, has been controlled to close, so that if the boost voltage or the inverter voltage, respectively, is equal to the voltage between the terminals of the charging socket, welding of the negative DC switch is detected, otherwise it is concluded that the negative DC switch has not been welded.

Advantageously, during the eighth comparison step, when the common mode voltage of the positive terminal of the charging socket is greater than the second low voltage limit, the method continues with a tenth comparison step of comparing the boost voltage or the inverter voltage, respectively, with the voltage between the terminals of the charging socket, respectively, after the negative DC switch has been controlled to close, so that if the boost voltage or the inverter voltage, respectively, is equal to the voltage between the terminals of the charging socket, 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 welded.

Drawings

Other features 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 schematic drawings, in which:

Fig. 1 schematically shows an electric vehicle or a 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 the charging of the charging system of the vehicle and diagnosing the power switch of the charging system,

Fig. 2 shows a first step of a charge termination and diagnosis method according to the invention carried out by the vehicle of fig. 1 in the case of a charge just ended using the boost stage of the charging system of the vehicle,

Fig 3 shows steps after the first steps of the charge termination and diagnosis method of fig 2 when these first steps do not diagnose any welding of the switch between the charging station and the boost stage,

Fig. 4 shows steps after the first step of the charge termination and diagnostic method of fig. 2 when there is still a voltage 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 flip (thus preventing access to the charging socket),

Fig. 5 shows a first step of a charge termination and diagnosis method according to the invention carried out by the vehicle of fig. 1 in the case of a charge just ended without using the boost level of the charging system of the vehicle,

Fig. 6 shows steps after the first step of the charge termination and diagnostic method of fig. 5 when there is still a voltage between the terminals of the charging socket and the computer of the vehicle implementing the method according to the invention does not have information about the potential closing of the charging flap, and

Fig. 7 shows steps after the steps of the charge termination and diagnostic method of fig. 2, 5 or 6 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 directly connected to the traction battery is not welded.

Detailed Description

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

The charging system 32 will now be described with reference to fig. 1 and other elements of the vehicle 30 in order to clearly illustrate how these power switches are used during charging of the traction battery 2.

The vehicle comprises a traction inverter 3 and a three-phase motor 4 connected to the wheels of the vehicle by means of a drive train, the inverter 3 and the motor 4 being supplied by a traction battery 2 in order to move the vehicle.

To this end, the vehicle comprises a first switch 11, called positive battery switch, for connecting the traction battery 2 to the inverter 3, connected by a first one of its terminals to the positive terminal of the traction battery 2 and by a second one of its terminals to the positive input terminal of the inverter 3, and a second switch 12, called negative battery switch, connected by a first one of its terminals to the negative terminal of the traction battery 2 and by a second one of its terminals to the negative input terminal of the inverter 3. The input of the inverter is intended here to mean the part of the inverter that receives DC current and transmits rectified current, i.e. the term "input" is to be understood in relation to the function of the inverter. Also, in this patent application, the terms "input" and "output" should be understood with respect to the function of the electrical component or part being referred to. The smoothing capacitor 7 is connected to the input of the inverter. When the inverter 3 functions as a rectifier of the current output by the motor 4 operating in the generator mode, the capacitor makes it possible to smooth the current into the battery 2.

The positive and negative battery switches 11, 12 thus form a connection between the traction battery 2 and the input of the inverter 3. Furthermore, the output of the inverter 3 is directly connected to the motor 4, i.e. without intermediate switches.

The vehicle further comprises a charging socket 8, which is connected to the DC charging station 60 via a charging cable 70. For example, the charging socket 8 is a CHADEMO connector compliant with the standard IEC 61851-23, -24. As a variant, the vehicle comprises only one charging socket (for example a combined DC charging socket complying with standard IEC 62196-3) allowing to connect to both DC charging stations and AC charging stations. In this case, the vehicle 30 further includes an AC charging device. In yet another variation, the vehicle has only one charging receptacle that is intended to be connected to only a DC charging station.

The charging system 32 comprises a boost stage 5 comprising an inverter 3, a motor 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 motor 4 by a switch 16 (called boost switch), and the negative terminal of the capacitor 6 is connected to the negative input terminal of the inverter 3. The boost stage 5 is used by the vehicle during charging of the traction battery 2 using a charging voltage supplied by a charging station that is less than the maximum no-load voltage of the traction battery 2.

For this purpose, the charging system 32 comprises control means 40 of the inverter 3 and of the motor 4, which are able to convert 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, which are discharged into the traction battery 2 by 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 _B between the terminals of the capacitor 6. In addition to the means for measuring the voltage V _B, the charging system 32 also comprises means for measuring at least one phase current I _B flowing through the inverter 3.

The switch 16, which is called boost switch, is connected by a first one of its terminals to the positive terminal of the boost capacitor 6 and by a second one of its terminals to the neutral point of the motor 4. The boost switch 16 makes it possible to disconnect the boost capacitor 6 at the input of the boost stage 5 outside the phase of charging the traction battery 2 by the external charging station, the boost switch 16 remaining disconnected in particular when the vehicle is driven. Thus, when the vehicle is driven, capacitive coupling of the boost capacitor 6 with the motor 4 is avoided.

For example, the control device 40 of the inverter 3 is a microcontroller that controls the switching of the inverter 3 both in the traction mode and in the mode of charging the vehicle using the booster stage 5.

The charging system 32 further comprises means for connecting the charging socket 8 to the input of the boost stage 5, these means comprising:

A switch 13, called positive DC switch, connected by a first one of its terminals to the positive terminal of the charging socket 8 and by a second one of its terminals to the boost switch 16, and

A switch 14, called negative DC switch, connected by a first one of its terminals to the negative terminal of the charging socket 8 and by a second one of its terminals to the negative input terminal of the inverter 3.

These switches 13, 14 serve to recharge the traction battery 2 via the boost 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.

Finally, the charging system 32 also comprises means for directly connecting the charging socket 8 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 comprise a negative DC switch 14 and a switch 15, called bypass switch, which is connected by a first one of its terminals to a first one of the positive DC switches 13 and by a second one of its terminals to a second one of the positive battery switches 11.

The switches 11, 12, 13, 14 and 15 are grouped together in the connection box 9 of the charging system 32. The connection box 9 further includes a precharge relay 10 connected to the positive terminal of the traction battery 2 through one of its terminals and to the positive terminal of the inverter 3 through the other of its terminals. The precharge resistor is connected between the precharge relay 10 and the positive terminal of the battery 2. Before any charging of the battery 2, the precharge relay 10 is first closed to charge the smoothing capacitor 7, and then the precharge relay 10 is opened and the positive-electrode battery switch 11 is closed. The precharge relay 10 and the precharge resistor form a precharge device. It should be noted that other types of pre-charge devices may be used instead of such relay and resistor systems.

Charging system 32 also includes one or more software and/or hardware modules of a host computer 50 of the vehicle. In particular, the host computer 50 includes means for communicating with the charging station 60 and control means for the power switches 10, 11, 12, 13, 14, 15 and 16, which form 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 host computer 50 communicates, the management system 20 potentially forming an integral part of the charging system 32.

The system 20 for managing the traction battery 2 is coupled to a sensor 22 of the voltage V _DC between the current entering the battery and the terminals of the charging socket 8, which allows the system to supervise the charging of the battery 2. The voltage V _DC between the terminals of the charging socket 8 is a differential voltage between the two terminals of the charging socket 8. The system 20 for managing the battery 2 further comprises a bypass switch 15 and control means for the positive and negative DC switches 13, 14. Thus, when the system 20 for managing the battery 2 detects a fault during charging, the system can interrupt the charging for safety reasons without intervention by the host computer 50 of the vehicle. Thus, the switches 10, 11, 12, 13, 14, 15 are each controllable by the vehicle's management system 20 and host computer 50 to achieve redundancy in relation to safety. Likewise, the boost switch 16 may be controlled by the host computer 50 and the control device 40.

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

The main computer 50 of the vehicle uses the 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.

An embodiment of the method 1 according to the invention when the traction battery 2 has just been recharged using the boost stage 5 via the charging station 60 will now be described with reference to fig. 2. In this use case of the invention, the charging station 60 cannot supply a voltage of more than 400V, for example, while the traction battery 2 has a maximum no-load voltage of 800V. Thus, the charging current just ended flows in particular through the positive and negative DC switches 13, 14, the boost switch 16 and the positive and negative battery switches 11, 12, but without the use of the bypass switch 15, which remains open during charging.

The method 1 starts 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 diagnosis of the power switch of the vehicle 30 to be carried out. Thus, 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).

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.

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

After a few milliseconds, the method 1 carries out a following step 120, which is a first comparison step of comparing the voltage V _DC between the terminals of the charging socket 8 on the one hand with a predefined safety voltage S1 (here set equal to 60V) on the other hand. Of course, as a variant, another predefined safety voltage value may be selected, in particular according to current standards relating to electrical safety.

When in the first comparison step 120, method 1 determines that the voltage V _DC between the terminals of the charging socket 8 is less than (branched to) the predefined safety voltage S1, then 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 (cross-reference a) to step 470, which is shown in fig. 7 and described below. It should be noted that in this patent application, the comparison step uses strict or weak inequality conditions without changing the nature of the invention. Therefore, the strictness or weakness of the inequality is not specified in this embodiment of the present invention.

In contrast, when in the first comparison step 120, the method 1 determines that the voltage V _DC between the terminals of the charging socket 8 is greater than (branch no) the predefined safety voltage S1, then a second comparison step 130 of comparing the voltage V _DC between the terminals of the charging socket 8 on the one hand with the voltage V _B between the terminals of the capacitor 6 (referred to as boost voltage) measured by the charging system 32 on the other hand is performed after the first comparison step 120.

When in the second comparison step 130, method 1 determines that the difference in absolute value between the voltage V _DC between the terminals of the charging socket 8 and the boost voltage V _B is greater than (branch is) the predefined voltage offset S2 (equal to 30V in this embodiment of the invention), then 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, which is shown in fig. 7 and described below. Of course, another value may be selected for the predefined voltage offset S2, in particular depending on the use of the charging system 32.

When in the second comparison step 130, the method 1 determines that the difference in absolute value between the voltage V _DC between the terminals of the charging socket 8 and the boost voltage V _B is smaller (branch no) than the predefined voltage offset S2, then in case the sensor allowing the closing of the charging flap close to the charging socket 8 is active (branch yes of conditional 135), the next step is a step 170 of controlling the opening of the positive and negative battery switches 11, 12, then if one of the following conditions is met, the charging cable 70 is allowed to be disconnected:

The voltage V _DC between the terminals of the charging socket 8, 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 less than the predefined safety voltage S1, or

The voltage V _O between the terminals of the inverter 3 is less than the predefined safety voltage S1,

And if one of these conditions is met, the computer waits to receive an indication to close the flip cover and then proceeds (cross-reference B) to step 240, which is shown in fig. 4 and described below.

When in the second comparison step 130 the method 1 determines that the difference in absolute value between the voltage V _DC between the terminals of the charging socket 8 and the boost voltage V _B is smaller than the predefined voltage offset S2, and when the computer 50 of the vehicle does not have information about the potential disconnection of the charging cable 70 (no branch of conditional 135), for example because the vehicle 30 is not equipped with a sensor with a charging flap closed or the sensor is faulty, then 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 reaches a predefined voltage, for example 100V. For this purpose, the computer 5 uses the control device 40 of the inverter 3.

After waiting a few milliseconds, a third comparison step 150 of comparing the voltage V _DC between the terminals of the charging socket 8 on the one hand with the boost voltage V _B on the other hand is carried out after the discharging step 140.

When in the third comparison step 150, method 1 determines that the voltage V _DC between the terminals of the charging socket 8 is equal to the boost voltage V _B (branch yes), then method 1 detects 160 welding of the positive DC switch 13 and 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 shown in fig. 7 and described below.

It should be noted that in the case where both the negative and positive DC switches 14, 13 are diagnosed as welded, the disconnection is allowed after the positive and negative battery switches 11, 12 have been opened and it has been verified that the positive and negative battery switches are not welded.

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 been welded, i.e. they have not been blocked in the closed position. For example, this conclusion may be reached 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 (steps 490 and 545 described below with reference to fig. 7) that the common mode voltage of each of the terminals of the charging socket 8 is also less than the predefined safety voltage S1.

Method 1 then carries out the steps of fig. 2, which are aimed at determining the diagnosis of boost switch 16.

The first step of this new diagnosis is to control the boost switch 16 to open 180. The first step 180 of controlling the disconnection is followed by a step 190 of controlling the inverter 3 to discharge the capacitor 6, followed by a step 215 of comparing the boost voltage V _B with a low threshold S3 of the voltage of the capacitor 6 (for example 60V) or with a low threshold S4 of a few amperes of the phase current I _B in the inverter 3 (for example 5 amperes).

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

In contrast, if method 1 determines in comparison step 215 that 200 boost voltage V _B is still greater than low threshold S3 of the voltage of capacitor 6 after a few seconds, or that phase current I _B in inverter 3 remains near zero for a few milliseconds, this is because overdischarge of capacitor 6 is unlikely to occur, and thus method 1 determines in step 210 that boost switch 16 is not welded.

Fig. 3 illustrates the steps after the step of controlling the opening 170 of the positive and negative battery switches 11, 12 and the receipt of an indication by the computer 50 that the charge flap is closed. This closing occurs when the voltage V _DC between the terminals of the charging socket 8, previously measured in the first comparison step 120, is greater than the predefined safety voltage S1, and when the difference between the boosted voltage V _B and the voltage V _DC between the terminals of the charging socket is less than the predefined voltage offset S2. The positive and negative DC switches 13, 14 cannot be fully diagnosed. It should be noted that the indication of the charge flap closed may be derived by the computer 50 from the vehicle 30 being driven above a certain speed threshold (e.g., above 5 km/h).

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

It should be noted that in this configuration, the computer 50 also does not know whether the charge just ended is a charge using the boost stage 5 or a charge not using the boost stage 5, in other words, the computer 50 does not know whether it has to diagnose the positive and negative DC switches 13, 14, or the bypass switch 15 and the negative DC switch 14, respectively. Specifically, in this embodiment of the present invention, the type of charge that has just been performed is not stored in the memory in the computer 50.

The control step 240 is followed by a fourth comparison step 250 of comparing the voltage V _DC between the terminals of the charging socket 8 on the one hand with a low differential voltage threshold S5, which is set to 60V, for example.

In a fourth comparison step 250, if method 1 determines that the voltage V _DC between the terminals of the charging socket 8 is greater (branch no) than the low differential voltage threshold S5, this is because the two switches connected to the charging socket are fused. In this case, the next step is to compare the voltage V _DC between the terminals of the charging socket 8 with an intermediate differential voltage threshold S6, which is set to 500V here. If method 1 determines 260 that the voltage V _DC between the terminals of the charging socket 8 is less than the intermediate differential voltage threshold S6 and greater than the low differential voltage threshold S5, this is because the just-ended charge uses 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 _DC between the terminals of the charging socket 8 is between the intermediate differential voltage threshold S6 and the high differential voltage threshold S7, corresponding to 900V for example, this is because the boost stage 5 is not used for the charging just ended and the method 1 determines 290 that the bypass switch 15 and the negative DC switch 14 are welded.

In a fourth comparison step 250, if method 1 determines that the voltage V _DC between the terminals of the charging socket 8 is less than (branched to) the low differential voltage threshold S5, this is because at least one of the two switches connected to the charging socket is fused.

In this case, a fifth comparison step 300 of comparing the common-mode voltage v+ of the positive terminal of the charging socket 8 on the one hand with a low common-mode voltage threshold S8, which is set to 60V, for example, is performed after the fourth comparison step 250. If the common mode voltage V + of the positive terminal of the charging jack 8 is less than (branch is) the low common mode voltage threshold S8, then method 1 determines 310 that neither the bypass switch 15 nor the positive DC switch are welded. In contrast, if method 1 determines that the common mode voltage v+ of the positive terminal of charging jack 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 charging jack 8 to an intermediate common mode voltage threshold S9, which is set to 500V, for example. If method 1 determines 320 that the voltage V _DC between the terminals of the charging jack 8 is less than the intermediate common mode voltage threshold S9 and greater than the low common mode voltage threshold S8, then this is because the just-ended charge uses 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 _DC between the terminals of the charging socket 8 is between the intermediate common mode voltage threshold S9 and the high common mode voltage threshold S10, corresponding to 900V for example, this is because the boost stage 5 is not used for the charging just ended and the method 1 determines 350 that the bypass switch 15 and the negative DC switch 14 are welded.

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 _DC between the terminals of the charging socket 8 is less than the low differential voltage threshold S5), a sixth comparison step 360 of comparing the common-mode voltage V-of the negative terminal of the charging socket 8 on the one hand with a low common-mode voltage level S11, for example set to 60V, on the other hand, is performed after the fourth comparison step 250. If the common mode voltage V-of the negative terminal of the charging jack 8 is less than (branch is) the low common mode voltage level S11, then method 1 determines 370 that the negative DC switch 14 is not welded. In contrast, if the common mode voltage V-of the negative terminal of the charging jack 8 is greater (branch no) than the low common mode voltage level S11, then method 1 determines 380 that the negative DC switch 14 is welded.

An embodiment of the method 1 according to the invention when the traction battery 2 has just been recharged via a charging station 60 without the use of the boost stage 5 will now be described with reference to fig. 5. In this use case of the invention, the charging station 60 is able to supply a voltage greater than or equal to the maximum no-load voltage (800V) of the traction battery 2. Thus, the charging current just ended flows in particular through the negative DC and bypass switches 14, 15 and the positive and negative battery switches 11, 12, but without the boost switch 16, which remains open during charging. In this case of use, the first step of method 1 is essentially the same as in the case of charging using the boost stage 5, and will therefore be referenced in the same way, while nevertheless indicating the differences related to the switch in question and to some comparison voltage.

The method 1 starts with a first step 100, which is identical to the first step in 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.

The next step 110 is to control the negative DC switch and the bypass switches 14, 15 to open.

After a few milliseconds, the method carries out a following step 120, which is a first comparison step comparing the voltage V _DC between the terminals of the charging socket 8 on the one hand with the predefined safety voltage S1 on the other hand.

When in the first comparison step 120, method 1 determines that the voltage V _DC between the terminals of the charging socket 8 is less than (branched to) the predefined safety voltage S1, then 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, which is shown in fig. 7 and described below.

In contrast, when in the first comparison step 120, the method 1 determines that the voltage V _DC between the terminals of the charging socket 8 is greater than (branch no) the predefined safety voltage S1, then a second comparison step 130 of comparing the voltage V _DC between the terminals of the charging socket 8 on the one hand with the voltage V _O between the terminals of the inverter 3 (referred to as inverter voltage) measured by the charging system 32 on the other hand is performed after the first comparison step 120.

When in the second comparison step 130, method 1 determines that the difference in absolute value between the voltage V _DC between the terminals of the charging socket 8 and the inverter voltage V _O is greater than (branch yes) the predefined voltage offset S2, then 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, which is shown in fig. 7 and described below.

When in the second comparison step 130, the method 1 determines that the difference in absolute value between the voltage V _DC between the terminals of the charging socket 8 and the inverter voltage V _O is smaller (branch no) than the predefined voltage offset S2, then in the event that the sensor of the charging flip-off is active (branch yes of conditional 135), the next step is a step 170 of controlling the opening of the positive and negative battery switches 11, 12, then allowing the disconnection of the charging cable if one of the following conditions is met:

Inverter voltage V _O is less than predefined safety voltage S1,

And if one of these conditions is met, the computer 50 waits to receive an indication of lid closure and then proceeds to step 240, which is shown in fig. 4, step 240 and subsequent steps being the same as in the case of charging using the boost stage 5.

When in the second comparison step 130, the method 1 determines that the difference in absolute value between the voltage V _DC between the terminals of the charging socket 8 and the inverter voltage V _O is smaller than the predefined voltage offset S2, and when the computer 50 of the vehicle does not have information about the potential disconnection of the charging cable (no branch of conditional 135), for example because the vehicle is not equipped with a sensor for closing the charging flap or the sensor is faulty, then the method 1 proceeds (cross-reference C) to the step illustrated in fig. 6. The steps are as follows:

control the positive and negative battery switches 13, 14 to open 390, then after a few seconds,

An additional comparison 400 of the voltage V _DC between the terminals of the charging socket 8 with the predefined safety voltage S1 and if the voltage V _DC between the terminals of the charging socket 8 is less than (branch is) the predefined safety voltage S1, the following is done:

-controlling the positive and negative battery switches 13, 14 to close 410, then

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

In contrast, if in the additional comparison step 420, method 1 determines that the voltage V _DC between the terminals of the charging socket 8 is less than (branched yes) the predefined safety voltage S1, then 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, which is shown in fig. 7 and described below.

When the voltage V _DC between the terminals of the charging socket 8 is greater (branch no) than the predefined safety voltage S1 during the additional comparison 400, then a step 440 of comparing the inverter voltage V _O with the predefined safety voltage S1 is performed after the additional comparison step 400. If the inverter voltage V _O is less than (branch yes) the predefined safety voltage S1, 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, which is shown in fig. 7 and described below. In contrast, if the inverter voltage V _O is greater (branch no) than the predefined safety voltage S1, then method 1 prevents 460 the user from disconnecting the charging cable 70 and looping back to the additional comparison step 400. In particular, in this case, there is a continuous dangerous voltage between the terminals of the charging socket 8 and between the terminals of the inverter, which may be the result of simultaneous welding of the switches 62, 64 of the charging station 60 and the negative DC and bypass switches 14, 15, or the switches 62, 64 of the charging station 60 and the positive and negative battery switches 11,12, or even the negative DC and bypass switches 14, 15 and the positive and negative battery switches 11, 12. The user must then press an emergency button on the charging station 60 to reduce the voltage delivered by the charging station and allow the charging outlet 8 to disconnect.

Finally, when the method 1 determines that at least one of the bypass switch 15 and the negative DC switch 14 is not welded in the case where the boost stage 5 is not used for charging or that at least one of the negative DC switch and the positive DC switch 14, 13 is not welded in the case where the boost stage 5 is not used for charging in one of the cases mentioned above with respect to fig. 2, 5 or 6, then the following operations are performed:

allowing the user to disconnect the charging cable, and

The method 1 proceeds with the step of fig. 7, i.e. step 470 of controlling the bypass switch 15 and the switch of the positive and negative DC switches 13, 14 which has not been controlled to be open.

During this step 470 of controlling opening, the positive and negative battery switches 11, 12 remain closed.

Then, the step 470 of controlling the disconnection is followed by two comparison steps, performed in parallel and/or one after the other, these steps being:

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 (e.g. 60V) on the other hand, and

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 a second low common mode voltage limit S13 (e.g. 60V) on the other hand.

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

In contrast, when in the seventh comparison step 480, method 1 determines that the common mode voltage V-of the negative terminal of the charging socket 8 is greater than (branch no) the first low common mode voltage limit S12, then a step 500 of controlling the positive DC switch (if charging uses the boost stage 5) or the bypass switch 15 (if charging does not use the boost stage 5) to close follows the seventh comparison step 480.

After a few milliseconds, the step 500 of controlling closure is followed by a ninth comparison step 510 in which, when charging uses a boost stage, method 1 compares the boost voltage V _B on the one hand with the voltage V _DC between the terminals of the charging socket 8 on the other hand, and if the boost voltage V _B is equal to the voltage V _DC between the terminals of the charging socket 8 (branch yes), 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 the boost stage is not used for charging, in a ninth comparison step 510, method 1 compares the inverter voltage V _O on the one hand with the voltage V _DC between the terminals of the charging socket 8 on the other hand, and if the inverter voltage V _O is equal to the voltage V _DC between the terminals of the charging socket 8 (branch yes), 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.

Similarly, when in the eighth comparison step 540, method 1 determines that the common mode voltage v+ of the positive terminal of the charging jack 8 is greater than (branch no) the second low common mode voltage limit S13, then a step 550 of controlling the negative DC switch to close follows the eighth comparison step 540.

After a few milliseconds, the step 550 of controlling closure is followed by a tenth comparison step 560 in which, when charging uses a boost stage, method 1 compares the boost voltage V _B on the one hand with the voltage V _DC between the terminals of the charging socket 8 on the other hand, and if the boost voltage V _B is equal to the voltage V _DC between the terminals of the charging socket 8 (branch yes), 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 the boost stage 5 is not in use for charging, in a tenth comparison step 560, method 1 compares the inverter voltage V _O on the one hand with the voltage V _DC between the terminals of the charging socket 8 on the other hand, and if the inverter voltage V _O is equal to the voltage V _DC between the terminals of the charging socket 8 (branch yes), 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.

Of course, the invention is not limited to the examples just 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 the charging of a charging system (32) of an electric or hybrid vehicle (30) and 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 powering a motor (4) of the vehicle (30), the charging system (32) comprising at least:

-a switch (11), called positive battery switch, connected by a first one of its terminals to the positive terminal of the traction battery (2) and by a second one of its terminals to the positive input terminal of the inverter (3), and

A switch (12), called a negative battery switch, connected by a first of its terminals to the negative terminal of the traction battery (2) and by a second of its terminals to the negative input terminal of the inverter (3),

A boost stage (5) comprising at least one capacitor (6) with its positive terminal connected to the positive input terminal of the boost stage (5) and its negative terminal connected to the negative input terminal of the boost stage (5),

-Two switches (13, 14, 15), called switches to be tested, used during charging, a first switch (13, 15) to be tested being connected by a first one of its terminals to the positive terminal of the charging socket (8) and by a second one of its terminals to the positive input terminal of the charging socket (5), a second switch (14) to be tested being connected by a first one of its terminals to the negative terminal of the charging socket (8) and by a second one of its terminals to the second terminal of the negative battery switch (12), when the charging uses the boost stage (5), the method (1) comprising:

A step (110) of controlling the opening of the switches (13, 14, 15) to be tested,

A first comparison step (120) of comparing the voltage (V _DC) between the terminals of the charging socket (8) on the one hand with a predefined safety voltage (S1) on the other hand,

The method (1) further comprises when the voltage (V _DC) between the terminals of the charging socket (8) is greater than the predefined safety voltage (S1):

A second comparison step (130) of comparing the voltage (V _DC) between the terminals of the charging socket (8) on the one hand with the voltage between the second terminals of the switches (13, 14, 15) to be tested on the other hand,

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 smaller than a predefined voltage offset (S2), and in the absence of information about the closing of the charging flap of the vehicle (30) for approaching the charging socket (8), the method (1) additionally comprises a step (140) of discharging the capacitor (6), and then a third comparison step (150) of comparing the voltage (V _DC) between the terminals of the charging socket (8) on the one hand with the voltage (V _B) between the second terminals of the switches (13, 14) to be tested on the other hand.

2. The charge termination and diagnostic method (1) of claim 1, wherein the motor (4) and the inverter (3) form part of the boost stage (5), the boost stage (5) comprising a switch (16), called boost switch, connected by a first one of its terminals to the positive terminal of the capacitor (6) and by a second one of its terminals to the neutral point of the motor (4), the method (1) being characterized in that it comprises the steps of, when the boost stage (5) is used by the charge and when the method (1) does not diagnose any welding of the switches (13, 14) to be tested:

-controlling the boost switch (16) to open (180),

-Controlling (190) the inverter (3) to discharge the capacitor (6),

-Comparing (215) the voltage (V _B) between the terminals of the capacitor (6) or the phase current of the inverter (3) with a low threshold (S3, S4) of the voltage of the capacitor (6) or the phase current (I _B), respectively, and detecting (230) a welding of the boost switch (16) if the voltage (V _B) between the terminals of the capacitor (6) is smaller than the low threshold (S3) of the voltage of the capacitor (6) or if the phase current (I _B) of the inverter (3) is larger than the low threshold (S4) of the phase current (I _B).

3. The charge termination and diagnosis method (1) according to claim 1 or 2, wherein the charging system (32) comprises:

-a switch (13), called positive DC switch, connected by a first one of its terminals to the positive terminal of the charging socket (8) and by a second one of its terminals to the positive input terminal of the boost stage (5), and

A switch (14), called negative DC switch, connected by a first of its terminals to the negative terminal of the charging socket (8) and by 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), the voltage (V _B) between the second terminals of the switches to be tested (13, 14) is then referred to as the boost voltage.

4. The charge termination and diagnostic method (1) of claim 3, wherein the charging system (32) comprises a switch (15) called bypass switch, which is connected by a first of its terminals to the first terminal of the positive DC switch (13) and by a second of its terminals to the second terminal of the positive battery switch (11), the switches to be tested being the negative DC switch (14) and the bypass switch (15), the voltage (V _O) between the second terminals of the switches to be tested (14, 15) then being called inverter voltage when the boost stage (5) is not used by the charge.

5. The charge termination and diagnostic method (1) of claim 4, wherein a fourth comparison step (250) of comparing a voltage (V _DC) between terminals of the charging socket (8) on the one hand with at least one differential voltage threshold (S5) and an intermediate differential voltage threshold (S6) on the other hand is performed after the second comparison step (130) with the bypass switch (15), the positive DC switch (13) and the negative DC switch (14) controlled to open (240) and the positive battery switch (11) and the negative battery switch (12) controlled to close (240), irrespective of whether the charging uses the boost stage (5), so that if a voltage (V _DC) between terminals of the charging socket (8) is greater than the intermediate differential voltage threshold (S6), a welding (290) of the bypass switch (15) and the negative DC switch (14) is detected or if a voltage (V _DC) between terminals of the charging socket (8) is between the low differential voltage (S5) and the negative DC switch (14) is detected to the intermediate differential voltage (S6).

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

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

8. The charge termination and diagnostic method (1) of any one of claims 4 to 7, wherein when the boost stage (5) is not used by the charge, 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 closing of the charging flap of the vehicle (30) for approaching the charging socket (8), the method (1) proceeds with the following steps:

-controlling the positive and negative battery switches (13, 14) to open (390),

-An additional comparison (400) of the voltage (V _DC) between the terminals of the charging socket (8) with the predefined safety voltage (S1), and if the voltage (V _DC) between the terminals of the charging socket (8) is less than the predefined safety voltage (S1), the following is performed:

-controlling the positive and negative battery switches (13, 14) to close (410),

-An additional comparison (420) of the voltage (V _DC) between the terminals of the charging socket (8) with the predefined safety voltage (S1) and if the voltage (V _DC) between the terminals of the charging socket (8) is greater than the predefined safety voltage (S1), a 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 during an additional comparison (400) of the voltage (V _DC) between the terminals of the charging socket (8) with the predefined safety voltage (S1), when the voltage (V _DC) between the terminals of the charging socket (8) is greater than the predefined safety voltage (S1), the method proceeds with the steps of:

-comparing (440) the inverter voltage (V _O) with the predefined safety voltage (S1), thereby concluding that when the inverter voltage (V _O) is smaller than the predefined safety voltage (S1), at least one of the bypass switch (15) and the negative DC switch (14) is not welded, otherwise preventing (460) disconnecting a charging cable (70) connected with the charging socket (8), the step being cycled back to the additional comparing step (400).

10. The charge termination and diagnostic method (1) of any one of claims 3 to 9, wherein when the third comparing step (150) determines that the voltage (V _DC) between the terminals of the charging socket (8) is equal to the boost voltage (V _B), then the method (1) detects (160) 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. The charge termination and diagnostic method (1) of any one of claims 3 to 10, wherein when the charge uses the boost stage (5) and when the first comparison step (120) determines that the voltage (V _DC) between the terminals of the charging socket (8) is less than the predefined safety voltage (S1) or when the second comparison step (130) determines that the difference between the boost voltage (V _B) and the voltage (V _DC) between the terminals of the charging socket (8) is greater than the predefined voltage offset (S2), then the method (1) determines that at least one of the positive DC switch (13) and the negative DC switch (14) is not welded.

12. The charge termination and diagnostic method (1) of any one of claims 4 to 11, wherein when the charge does not use the boost stage (5) and when the first comparison step (120) determines that the voltage (V _DC) between the terminals of the charging socket (8) is less than the predefined safety voltage (S1) or when the second comparison step (130) determines that the difference between the voltage (V _O) of the inverter and the voltage (V _DC) between the terminals of the charging socket (8) is greater than the predefined voltage offset (S2), then the method (1) determines that at least one of the bypass switch (15) and the negative DC switch (14) is not welded.

13. The charge termination and diagnosis 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 with the charge using the boost stage (5) or that at least one of the bypass switch (15) and the negative DC switch (14) is not welded with the charge using the boost stage (5), the method (1) continues with a seventh comparison step (480) comparing the common mode voltage (V-) of the negative terminals of the charging jack (8) on the one hand with a first low common mode voltage limit (S12) on the other hand, if the negative DC switch (14) and the positive DC switch (13) or the bypass switch (15) on the other hand, respectively, are controlled to open (470), whereby it is concluded that the negative common mode voltage (V-) of the negative terminals of the charging jack (8) is welded with the first low common mode voltage limit (S12) when the common mode voltage (V-) of the negative terminals of the charging jack (8) is smaller than the first low common mode voltage limit (S12), and the method (1) continues with an eighth comparison step (540) of the common mode voltage (V-) of the negative terminals of the negative terminal (8) on the other hand, it follows 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 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) proceeds with a ninth comparison step (510) of comparing the boost voltage (V _B) or the inverter voltage (V _O), respectively, with the voltage (V _DC) between the terminals of the charging socket (8), respectively, after the positive DC switch (13) or the bypass switch (15), respectively, has been controlled to close (500), whereby if the boost voltage (V _B) or the inverter voltage (V _O), respectively, is equal to the voltage (V _DC) between the terminals of the charging socket (8), welding (520) of the negative DC switch (14) is detected, else it is concluded that the negative DC switch (14) has not been welded (530).

15. The charge termination and diagnostic method (1) of 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) proceeds with a tenth comparison step (560) of comparing the boost voltage (V _B) or the inverter voltage (V _O), respectively, with the voltage (V _DC) between the terminals of the charging socket (8), respectively, after the negative DC switch (14) has been controlled to be closed (550), so that if the boost voltage (V _B) or the inverter voltage (V _O), respectively, is equal to the voltage (V _DC) between the terminals of the charging socket (8), respectively, welding (570) of the positive DC switch (13) or the bypass switch (15), respectively, is detected, otherwise it is concluded that the positive DC switch (13) or the bypass switch (15), respectively, has not been welded (580).