FR2960298A1 - Method for detecting connection defect of battery sensor in vehicle, involves comparing current information with current thresholds, and delivering alert information when current information is lower than current thresholds, respectively - Google Patents

Abstract

The method involves reading current information of a battery delivered by a battery sensor (BS), and comparing the current information with current thresholds. Alert information is delivered, when the current information of the battery is lower than one of the current thresholds during predetermined duration. Another alert information is delivered, when the current information of the battery is lower than the other current threshold.

Description

The present invention relates to the automotive field. BACKGROUND OF THE INVENTION More particularly, the invention relates to the detection and treatment of a terminal connection fault of the battery of a vehicle when the battery is equipped with a voltage / current measurement sensor called "battery sensor". The use of battery sensors in motor vehicles is expected to grow strongly given the current need to optimize battery management. The need to reduce CO2 emissions in new generations of vehicles leads to the development of new control strategies aimed at limiting fuel consumption and, correspondingly, CO2 emissions. These new control strategies require a precise knowledge of the energy state of the battery. It thus becomes possible, for example, thanks to tight management of the battery, to order a temporary load shedding of the alternator, for example to facilitate reworking in a vehicle with reduced thermal motorization ("engine downsizing" in English terminology), or to command a stop of the engine in an automatic stop / restart strategy while having the assurance of having enough energy in the battery to restart the engine. With reference to FIG. 1, an example configuration is described below using a battery sensor BS in an automatic shutdown / restart system of the heat engine. 2 The system of Fig.1 is shown in a simplified manner and comprises a S / G alternator-starter equipped with its analog-digital converter and its control unit (not shown). The alternator / starter S / G is mechanically coupled to the crankshaft of a heat engine EN. Furthermore, the S / G alternator / starter is connected to a CAN-type communication bus through which it receives operating instructions issued by an engine control ECU. The S / G starter-alternator is inserted into an electrical power circuit connecting it, on the one hand, to the positive terminal B + of the battery and, on the other hand, to the mass of the vehicle itself connected to the negative terminal B- BAT battery.

As shown in FIG. 1, the battery sensor BS is here intended to be mounted at the negative terminal B- of the battery BAT. A lug CS of the sensor BS is intended to be electrically connected to the negative terminal B-. Conventionally, the sensor BS essentially comprises a series shunt (not shown) and electronic measurement circuits. The shunt is traversed by an Ibat battery current and allows the taking of a measurement voltage representative of it. Here Ibat is the intensity of the battery current, incoming or outgoing current, the direction of this current is not significant in the present invention. The voltage Vbat across the battery BAT is also measured by the sensor BS and, in addition, electrically feeds it. The current Ibat and voltage Vbat measured are digitized in the sensor BS is then transmitted to the ECU engine control unit through a LIN type serial communication link. In the battery sensor, as briefly described above, the inventive entity has noted the possible occurrence of a fault situation in the case of a faulty connection of the BS sensor to the battery terminal B- . The arrow FD in Fig.1 shows a non-connection of the terminal CS of the sensor on the terminal B-, non-connection which is consecutive, for example, a disengagement of the pod CS due to insufficient mechanical tightening. The connection of the B-terminal to the vehicle ground is done here through an electric cable L1 connected to the sensor BS. The non-connection of the terminal CS to the terminal B- therefore means that the battery BAT is no longer connected to the on-board electrical network. When the above situation occurs while the electric machine S / G (in alternator mode) is rotating and delivers a regulated DC voltage of 14 V, the sensor BS can output measurement information, Vbat and Ibat, which will appear as consistent for the ECU, so that this unit will be unable to detect the fault.

Indeed, if the S / G machine is rotating, it is it that feeds the vehicle electrical system and the disconnection of the pod CS has no detectable consequence. The sensor BS measures a coherent voltage Vbat of about 14 V and a substantially zero current, Ibat = 0 A approximately. The voltage Vbat = 14 V is in this case provided by the machine S / G and not by the battery BAT. The current Ibat is substantially zero because no current passes through the sensor BS, which is normal since the battery BAT is disconnected. This pair of values Vbat = 14 V, Ibat = 0 A, does not allow the discrimination of a fault because these values can be provided by the sensor BS under normal conditions of use, for example, when the vehicle is traveling at constant speed on the highway for some time. In such a case, the battery BAT will be well charged, Vbat = 14 V, and no current or a very weak current 4 will cross the battery BAT, Ibat = 0 A approximately. Such a situation is likely to generate control errors on the part of the strategies implemented in the vehicle and cause malfunctions. For example, in the case of the automatic stop / restart system of FIG. 1, the control strategy of the system could cause a shutdown of the heat engine EN while the battery BAT is disconnected and it will then be impossible to restart. the engine EN. The present invention provides improvements to solve the aforementioned problems of the prior art.

The invention relates to a method for detecting a connection fault for a battery sensor in a motor vehicle comprising steps of: reading a battery current information delivered by the sensor; comparing the battery current information with first and second current thresholds, the second current threshold having a value lower than that of the first current threshold; providing a first alert information when the battery current information is less than the first current threshold; and providing a second alert information when the battery current information is less than the second current threshold.

According to a particular embodiment, the first warning information is delivered when the battery current information is lower than the first current threshold for at least a first predetermined duration. According to a particular feature, the second alerting information is delivered when the battery current information is less than the second current threshold for at least a second predetermined duration. According to another particular embodiment, the step of issuing a first warning information item 10 comprises sub-steps of: delivering a first low battery current indication information when the battery current information is less than first current threshold for at least a third predetermined duration; and delivering the first alert information when the first low battery current indication information persists for at least a fourth predetermined duration. According to yet another particular embodiment, the step of providing a first alerting information comprises substeps of: providing a second low battery current indication information when the battery current information is less than the second current threshold for at least a fifth predetermined duration; and delivering the first alert information when the second low battery current indication information persists for at least a sixth predetermined duration. According to yet another particular embodiment, the step of providing a second alerting information comprises substeps of: controlling an increase of the battery current; providing a second low battery current indication information when the battery current information remains below the second current threshold despite the increase in the battery current controlled at the substep of controlling; and delivering the second alert information when the second low battery current indication information persists for at least a seventh predetermined duration.

According to a particular characteristic, an increase in the battery current is obtained by controlling an increase in the regulation setpoint voltage of an alternator or alternator-starter of the vehicle.

According to yet another particular embodiment, the low battery current indication information is delivered to a vehicle electrical energy management system. According to a particular characteristic, the warning information is delivered by said electrical energy management system equipping the vehicle. According to another particular characteristic, the issuing of an alert information commands the activation of a corresponding light indication on the dashboard of the vehicle. The detailed specifications of the invention are given in the following description in conjunction with the accompanying drawings. It should be noted that these drawings have no other purpose than to illustrate the text of the description and do not constitute in any way a limitation of the scope of the invention.

Fig.1 shows an example of electrical circuit configuration with battery sensor in an automatic shutdown / restart system of heat engine; FIG. 2 is a block diagram of a first embodiment of the method according to the invention in which the detection of a connection fault of the sensor uses only a processing internal to the sensor; FIGS. 3A and 3B are diagrams showing different exchanges and processing operations involved in another embodiment of the method in which the detection of a sensor connection fault uses internal and external processing of the sensor.

With particular reference to Fig.2, it is now described the first embodiment of the method according to the invention. As it appears in FIG. 2, in this embodiment of the method according to the invention, the detection of a connection fault of the sensor BS is based on the comparison of the current Ibat passing through the sensor at first and second thresholds of current, I1 and I2, and on time filtering performed from first and second threshold times, D1 and D2. The values of the current thresholds I1 and I2 and the threshold durations D1 and D2 are predetermined values, stored in the sensor BS, and the connection fault detection process can therefore be performed entirely inside the sensor BS. For example, in this embodiment, the values of the current thresholds I1 and I2 are set to 1A and 100mA, and the values of the threshold times D1 and D2 are both set to 2s.

The method here essentially comprises five steps S1 to S4. Steps S1 and S2 are conditional steps that detect crossing of the first and second current thresholds I1 and I2 during the first and second threshold times D1 and D2, respectively. In step S1, the current Ibat is compared to the first current threshold I1. This comparison is made in absolute value, that is to say that the direction of current Ibat is not taken into account. If the current Ibat is lower (output "Y" of the step) at the first current threshold I1 = 1A for a continuous duration at least equal to the first threshold duration D1, a second comparison is made in step S2 . In the opposite case (output "N" of the step Si), the processing loop on the step S1. It will be noted here that according to other embodiments of the method according to the invention, the current threshold I1 does not have a predetermined fixed value but a value which is a function, I1 = f (Ubat), of the voltage Ubat of battery. In step S2, the current Ibat is compared with the second current threshold I2. As for the comparison of step S1, this comparison of Ibat to I2 is made in absolute value. If the current Ibat is lower (output "Y" of the step) at the second current threshold I2 = 100 mA for a continuous duration greater than the second threshold duration D1, a so-called major alert ALT MAJ is generated, at the step S3. In the opposite case (output "N" of the step S2), a so-called minor alert ALT MIN is generated, in the step S4 and the processing then loop on the step S1. The ALT MIN and ALT MAJ alerts correspond to a current Ibat between I1 = 1A and I2 = 100 mA and an Ibat current lower than I2 = 100 mA, respectively. These alerts ALT MIN and ALT MAJ are transmitted to the ECU unit by the sensor BS, for example through the LIN communication link (FIG. 1), for consideration by the control strategies concerned. The durations D1 and D2 make it possible to carry out a filtering by discarding transient, or temporary, insignificant values. As a variant, these ALT MIN and ALT MAJ alerts are transmitted, not to the vehicle engine control ECU as indicated above, but to another ECU or to a vehicle electrical energy management system ("Electrical"). Energy Management System "or" EEMS "in English terminology).

ALT MIN alert is a "low level" alert and may lead, depending on the applications, to the activation of a LED 0, for example orange, on the dashboard of the vehicle. The ALT MAJ alert is a higher level alert (with a much lower current threshold) and may result, depending on the application, on the activation of an R LED, for example red, on the board. of the vehicle. In the embodiment which has just been described, the ALT MIN and ALT MAJ alerts are considered by the control strategies as indicators which must then be interpreted according to the situation of the vehicle. In the case where ALT MIN is activated, that is to say ALT MIN = "1", the sensor BS has detected a current Ibat of less than 1A for at least 2 s, which corresponds to a current value. weak that needs to be interpreted by the strategy. This value can be normal and correspond to a motorway traffic or abnormal and correspond to a disconnection of the sensor BS. In the case where ALT MAJ is activated, that is ALT MAJ = "1", the sensor BS has detected a current Ibat of less than 1 mA for at least 2 s, which corresponds to a very current value. low which corresponds to a strong presumption of battery disconnection. Indeed, except in the case of a specific strategy implemented in the vehicle, it is rare that the current Ibat in the battery is less than 100 mA. This ALT MAJ indicator shall be interpreted by the control strategy when the S / G electrical machine (in alternator mode) is rotating, in other words, when the EN engine is running and drives the S / G machine in alternator mode. . In this embodiment, the ALT indicator MIN, ALT MAJ, re-initializes in the state "0" when the value of the current Ibat comes to exceed three times the current threshold I1, I2, corresponding which controls the lifting at "1" of the indicator. Thus: - ALT MIN = "0" when a current Ibat> 3 A is detected; and - ALT MAJ = "0" when a current Ibat> 300 mA is detected. An advantage of this first embodiment of the method according to the invention lies in the fact that it can be developed independently of the control strategies implemented in the vehicle. With reference to FIGS. 3A and 3B, a second embodiment of the method according to the invention is now described in which the BS sensor connection fault detection process uses internal and external sensor processing. BS. In this second embodiment, in order to increase the reactivity of the detection, the method according to the invention can be made to solicit a member of the vehicle, outside the sensor BS. This second embodiment of the method is well suited for an application in which a decision involving a possible security problem is at stake. The case of an ALT MIN minor alert is more particularly discussed in Fig.3A.

As shown in FIG. 3A, FILT1 filtering is performed when Ibat <I1 = 1A is detected. This filtering FILT1 is a filtering over a duration D3, of the type described above for the first embodiment of the method. If the current Ibat remains below I1 = 1A for at least the duration D3, an indicator LCB1 = "1" of low battery current is generated by the sensor BS and is transmitted to an electrical energy management system EEMS equipping the vehicle. A FILT2 filtering over a duration D4 is carried out in the EEMS system. If the LCB1 indicator remains active, ie in the "1" state, for at least the duration D4, an ALT MIN alert is generated in the EEMS system. The ALT MIN alert is reported to the vehicle's VRF driver via an O LED.

In the above process, generating the ALT MIN alert uses not only the BS sensor but also the EEMS system. It will be noted that I1 can be a function of the voltage Ubat. Moreover, in this embodiment, the duration D4 can also be adjusted, according to certain known information of the EEMS system 12, for example, according to a history of evolution of the Ibat current managed and available in the EEMS system. . The generation time of an ALT MIN alert can therefore be reduced, or extended, depending on the information available to the EEMS system. The case of a major alert ALT MAJ is more particularly discussed in Fig.3B. As shown in FIG. 3B, the detection of a current Ibat <I2 = 100 mA triggers a processing process similar to that of FIG. 3A for the generation of an ALT MIN alert, at first, after having generated an indication LBC2 = "1" of low battery current transmitted to the EEMS system. On the other hand, the filings carried out FILT3 (D5) and FILT4 (D6) in the sensor BS and the EEMS system may be different from those carried out in the treatment of FIG. 3A. As also shown in Fig.3B, after generating the ALT MIN alert, an ALT MAJ alert can also be generated. However, in this second embodiment of the method, the alert ALT MAJ is generated not on a suspicion of a connection fault, but after performing a check. In the case of this second embodiment of the method according to the invention, this verification is performed by means of a modification of the voltage setpoint supplied to the machine S / G (alternator mode) and a control of the result of this modification on the current Ibat measured by the sensor BS.

As shown in FIG. 3B, after the generation of the ALT MIN alert, the EEMS system transmits to the engine control ECU unit a request DEM VR for increasing the control regulation voltage. The ECU then delivers an increased regulation command VR command, 13 for example, 14.5 V instead of 14 V previously. The VR command is transmitted to the machine S / G (alternator mode) which then applies at output a voltage Ubat = 14.5 V to the battery BAT. The exchanges between the EEMS system, the ECU unit and the S / G machine take place through the CAN bus in the configuration of FIG. Of course, in other configurations, exchanges may occur, not through the CAN bus of the vehicle, but for example through dedicated communication links of the series type. In the case where the low current (Ibat <100 mA) measured by the sensor BS is not the consequence of a connection fault, the increase of the Ubat voltage to 14.5 V, instead of 14 V, should normally produce an increase of the current Ibat, which must then pass above the threshold I2 = 100 mA. Otherwise, that is, in the case where the LBC indicator remains active "1", the processing process decides that the connection fault is real and triggers an ALT update alert. However, as shown in FIG. 3B, the ALT MAJ alert is effectively generated only if the indicator LCB2 = "1" is maintained for at least one duration D7 defined by a FILT5 filtering. It should be noted here that the discrimination described above between a normal state and a connection fault of the battery can be made by other means than through an increase in the charging voltage of the battery, insofar as this discrimination remains transparent to the DRV driver and does not cause any detectable disturbance by the driver. In general, it is necessary to generate an event that would force an incoming or outgoing Ibat current under normal operating conditions. Thus, for example, this discrimination can also be obtained by controlling the activation of an electrical consumer, for example, that of the rear defrosting device for a few seconds, which activation should normally cause an increase in the current Ibat measured by the sensor. BS.

Claims (10)

REVENDICATIONS1. A battery sensor (BS) connection fault detection method in an automotive vehicle comprising steps of: reading a battery current information (Ibat) output from said sensor (BS); comparing said battery current information (Ibat) with first (I1) and second (I2) current thresholds, said second current threshold having a lower value (I2 = 100mA) than that (I1 = 1A) of said first threshold current; delivering a first alert information (ALT MIN) when said battery current information (Ibat) is lower than said first current threshold (I 1); and providing a second alert information (ALT MAJ) when said battery current information (Ibat) is less than said second current threshold (12). 2. Method according to claim 1, characterized in that said first alerting information (ALT MIN) is delivered when said battery current information (Ibat) is lower than said first current threshold (I1) during at least a first predetermined duration (D1). 3. Method according to claim 1 or 2, characterized in that said second warning information (ALT MAJ) is delivered when said battery current information (Ibat) is lower than said second current threshold (I2) during minus a second predetermined duration (D2). 4. Method according to claim 1, characterized in that the step of delivering a first alert information (ALT MIN) comprises sub-steps of: delivering a first low battery current indication information (LCB1) when said battery current information (Ibat) is lower than said first current threshold (I1) for at least a third predetermined duration (D3); and delivering said first alert information (ALT MIN) when said first low battery current indication information (LCB1) persists for at least a fourth predetermined duration (D4). The method of claim 1, characterized in that the step of providing a first alert information (ALT MIN) comprises sub-steps of: providing a second low battery current indication information (LCB2) when said battery current information (Ibat) is lower than said second current threshold (I2) for at least a fifth predetermined duration (D5); and delivering said first alert information (ALT MIN) when said second low battery current indication information (LCB2) persists for at least a sixth predetermined duration (D6). 17 6. Method according to claim 1, characterized in that the step of issuing a second alerting information (ALT MAJ) comprises substeps of: controlling (DEM VR, VR) an increase of the battery current (Ibat) ; providing a second low battery current indication information (LCB2) when said battery current information (Ibat) remains lower than said second current threshold (I2) despite the increase of the battery current (Ibat) controlled at said sub -state to order; and delivering said second alert information (ALT MAJ) when said second low battery current indication information (LCB2) persists for at least a seventh predetermined duration (D7). 7. Method according to claim 6, characterized in that said increase of the battery current (Ibat) is obtained by controlling an increase in the control voltage setpoint (VR) of an alternator or alternator-starter (S / G) of the vehicle. The method according to any one of claims 4 to 7, characterized in that said low battery current indication information (LCB1, LCB2) is supplied to an electrical energy management system (EEMS) of the vehicle. 30 18 9. The method of claim 8, characterized in that said alerting information (ALT MIN, ALT MAJ) is issued by said electrical energy management system (EEMS) equipping the vehicle. 10. Method according to any one of claims 1 to 9, characterized in that the issuance of a said warning information (ALT MIN, ALT MAJ) controls the activation of a corresponding light indication (LED 0, LED R) on the dashboard of the vehicle.