VEHICLE TRACTION BATTERY DEVICE WITH SAFETY RELAY, DOUBLE-ACTING CONTROL

Abstract

A traction battery device for an electric or hybrid motor vehicle, comprising a battery equipped with electrochemical cells (4), an electromagnetic safety relay (10) including a winding surrounding a core connected to a contact carrying battery current, and a return spring applying an opening force to this contact, this device including a battery management system (6) which commands a direct current to the winding in one direction to close the contact, and in the opposite direction to open this contact. Figure 1

Description

Title of the invention: VEHICLE TRACTION BATTERY DEVICE WITH CONTROLLED SAFETY RELAY DOUBLE EFFECT

[0001] The present invention relates to a traction battery device of an electric or hybrid motor vehicle equipped with a double-acting controlled safety relay, as well as a method of operating this battery device and a motor vehicle equipped with such a device.

[0002] A type of battery device known for powering an electric traction machine of an electric or hybrid motor vehicle, presented in particular by document DE-AÏ-102013017409, comprises a high voltage battery delivering a current to several particular circuits arranged in parallel, each comprising a safety system installed in series in order to interrupt its current in the event of a failure resulting in an excessively high and dangerous intensity. The high voltage is generally between 400 and 800V.

[0003] A pyrotechnic cut-off device, called a "pyroswitch" in English, installed inside the battery box, comprises a detonator actuated by an electric control current delivered by the battery management system, called "battery management System" in English, "BMS" for short, to cut a connection bar directly at the output of the electrochemical elements of the battery delivering the electrical power. The pyrotechnic cut-off device has a high reactivity allowing it to intervene in a few milliseconds to completely open the internal circuit of the high-voltage battery in the event of a significant risk.

[0004] However, after activating the pyrotechnic cut-off device, it is necessary to open the battery box to change it, which is a delicate operation requiring significant time. With the purchase of new parts, the repair cost is high.

[0005] Another known cut-off device comprises an electromagnetic relay comprising a winding powered by a low voltage current controlled by the battery management system, which slides a core to close the relay by sticking an electrical contact passing the power to the output of the cells. This type of relay generally comprises a core return spring which, after the control current has been cut, opens the contact.

[0006] In this case, when the cut-off is triggered due to a problem detected in the vehicle's high-voltage network, after repairing this fault, it is sufficient to Reactivate the relay with power supplied by the management system to restore the connection at the cell output. There is no cost to intervene on the relay to reactivate it after a safety shutdown.

[0007] However, with use, the relay being able to pass a significant current, with in particular a heating of its contacts, we can obtain an aging of the materials of the contacts which causes a sticking of these contacts. We then obtain with the return spring of the core not being able to detach the contacts of the relay, or not quickly enough, during a request for safety of the high voltage circuit including a cut of the power supply to the winding, problems of passage of too high current which leads to risks of heating in the circuit or in the battery, and of starting a fire.

[0008] The present invention aims in particular to avoid these problems of the prior art.

[0009] To this end, it proposes a traction battery device for an electric or hybrid motor vehicle, comprising a battery equipped with electrochemical cells, an electromagnetic safety relay comprising a winding surrounding a core connected to a contact passing the battery current, and a return spring applying a force for opening this contact, this device being remarkable in that it comprises a battery management system which controls a direct current on the winding in one direction to close the contact, and in the opposite direction to open this contact.

[0010] An advantage of this battery device is that by keeping a relay generally used in single effect with a current only controlling its closing, including the return spring opening it automatically after stopping this control, with the battery management system applying a reverse current to obtain in its winding an opening force on the core, we add to that of the return spring a complementary return force which allows a detachment of the power contacts in the case of a sticking problem.

[0011] In addition, the management system can control current pulses with the reverse current, giving shocks which can help to detach the power contacts.

[0012] This improves the operational safety of the battery by reducing the risks of faults in its power circuit being cut off, while retaining a similar relay which can have the same size while the space generally available in a battery box is limited. In addition, it is not necessary to open the battery box and change components for a restart after a safety shutdown.

[0013] The battery device according to the invention may further comprise one or more of the following features, which may be combined with each other.

[0014] Advantageously, the relay comprises an axial rod fixed to the core, surrounded by the return spring, having a movable contact at one end.

[0015] In this case, advantageously the rod drives an adjustment spring which pushes axially on the movable contact to close the contact.

[0016] The invention also relates to a method of operating a battery device comprising any one of the preceding characteristics, remarkable in that after a command to open the contact by the battery management system, it controls the effective opening of this contact to apply, in the event of detection of a maintained closure, a strategy for controlling the reverse opening current.

[0017] In this case, advantageously the battery management system controls a reverse opening current which is not constant.

[0018] In particular, the method can control an opening reverse current comprising current pulses or oscillations.

[0019] Advantageously, the method applies a reverse opening current for a predefined duration of time, or after a predefined number of square pulses or oscillations of this current, or as a function of a limit of the temperature measured on the winding.

[0020] The invention further relates to an electric or hybrid motor vehicle comprising a traction battery forming part of a battery system comprising any one of the preceding characteristics, remarkable in that the battery is contained in a box containing the safety relay.

[0021] The invention will be better understood and other characteristics and advantages will appear more clearly on reading the description below given by way of example, with reference to the appended drawings in which:

[0022] [Fig.l] presents an electric or hybrid motor vehicle battery device according to the invention;

[0023] [Fig.2] is an axial sectional diagram of the relay of this battery device controlled in the closed position; and

[0024] [Fig.3] is a diagram of this relay controlled in the open position.

[0025] [Fig.l] shows a battery box 2 for supplying an electric traction machine of a motor vehicle, comprising electrochemical cells 4 connected together in series, which deliver via a positive terminal 20 and a negative terminal 22 a current to several particular circuits arranged in parallel 8, each comprising in series a secondary fuse 24 and an electrical system 26.

[0026] The positive pole of the electrochemical cells 4 supplies in series a circuit successively comprising a controlled general safety relay 10, a controlled main relay 12 arranged in parallel with a precharging circuit 14 comprising a resistor and a precharging relay in series, a resistor with a measurement of the potential difference at its terminals forming a current sensor 16, then a fuse main 18 before arriving at the positive terminal 20 of the battery box 2. The negative pole of the electrochemical cells 4 is connected by a manual contactor 28 to the negative terminal 22 of the battery box 2.

[0027] A battery management system 6 receives information from the electrochemical cells 30, the current sensor 16 and external vehicle control systems 32, to issue commands to the safety relay 10, the main relay 12 and the precharge circuit relay 14.

[0028] The safety relay 10 which is closed when the vehicle is started, constitutes an essential safety feature. In the event of a failure on a particular circuit 8 which does not cause its own secondary fuse 24 to open, or does not open quickly enough, or in the event of another serious problem such as an accident deforming the battery box 2, the safety relay 10 is then commanded to open in order to ensure complete isolation of the electrochemical elements 4 contained in this box.

[0029] In all cases it is necessary to ensure that the safety relay 10 actually opens when a command is given to obtain a sufficient level of safety.

[0030] [Fig.2] shows a safety relay 10 comprising an external housing 40 equipped with lateral tabs 42 for its fixing, receiving electric cables 44 for the passage of the power current passing through an internal contact 64, and for its control.

[0031] An axial rod 50 has at its end facing a forward direction AV a movable contact 58 arranged opposite two poles of a fixed contact 56, to connect these two poles by a support of the movable contact, and at its rear end a core 48 surrounded by a winding of electric wire 46.

[0032] A helical return spring 52 arranged in front of the core 48, surrounding the axial rod 50, bears on a fixed hub of the winding 54 to apply a permanent return force towards the rear to this rod.

[0033] A helical adjustment spring 60 surrounding the axial rod 50 is arranged between a support of this rod and the movable contact 58 to allow a small adjustment movement of this movable contact relative to the rod when it slides forward.

[0034] When the winding 46 is energized with a direct closing current given by a voltage delivered by the management system 6, a closing force F is obtained applied to the core 48 which slides to its front stop, driving the rod 50, with compression of the return spring 52.

[0035] The movable contact 58 pushed by the adjustment spring 60 comes to bear on the fixed contact 56 with a small compression of this spring which allows the core 48 to complete its travel to its front stop, while limiting the pressure between the two contacts 56, 58.

[0036] When the control current delivered by the management system 6 is cut off, return spring 52 moves back the core 48 by driving the rod 50, with traction on the movable contact 58 by a collar 62 at the front end of this rod, given solely by the force of this spring.

[0037] In the event of the two contacts 56, 58 sticking together, presenting an adhesion greater than the force delivered by the return spring 52, the relay 10 remains closed, which poses safety problems.

[0038] [Fig. 3] shows, for the opening of the relay 10, the application by the battery management system 6 of an inverted opening voltage relative to the closing voltage, giving an inverse current on the winding 46 which applies an opening force O towards the rear on the core 48 adding to that delivered by the return spring 52. The rod 50 transmits by its front stop 62 a traction force on the movable contact 58.

[0039] Several strategies for opening the relay 10, and for detaching the contacts 56, 58 if necessary, are possible. The reverse opening current on the winding 46 can be applied only in the event of detection of a contact 64 remaining closed after a command to open it, or can be applied systematically during this opening request. A permanent check of the electrical continuity of the battery power circuit makes it possible to verify whether the contact 64 has opened.

[0040] The reverse opening current can be applied permanently, or intermittently with, for example, slots or current oscillations in order to produce a vibration generating a succession of shocks which can help to detach the contacts 56, 58.

[0041] Maintaining this type of current can be done in particular for a limited period of time, or after a defined number of slots, or as a function of a temperature limit reached by the winding 46 to protect it.

[0042] With the same type of relay initially intended to control only its closing, without modifying its size and its location in the battery box 2, by controlling the opening control current of the relay 10 delivered by the management system 6, a complementary function of taking off the contacts 56, 58 is obtained.

Claims

Claims

1. Traction battery device of an electric or hybrid motor vehicle, comprising a battery equipped with electrochemical cells (4), an electromagnetic safety relay (10) comprising a winding (46) surrounding a core (48) connected to a contact (64) passing the battery current, and a return spring (52) applying a force for opening this contact (64), characterized in that it comprises a battery management system (6) which controls a direct current on the winding (46) in one direction to close the contact (64), and in an opposite direction to open this contact (64).

2. Battery device according to claim 1, characterized in that the relay (10) comprises an axial rod (50) fixed to the core (48), surrounded by the return spring (52), having at one end a movable contact (58).

3. Battery device according to claim 2, characterized in that the rod (50) drives an adjustment spring (60) which pushes axially on the movable contact (58) to close the contact (64).

4. Method of operating a battery device according to any one of the preceding claims, characterized in that after a command to open the contact (64) by the battery management system (6), it controls the effective opening of this contact (64) to apply, in the event of detection of a maintained closure, a strategy for controlling the reverse opening current.

5. A method of operating a battery device according to claim 4, characterized in that the battery management system (6) controls an opening reverse current which is not constant.

6. A method of operating a battery device according to claim 5, characterized in that it controls an opening reverse current comprising current pulses or oscillations.

7. Method of operating a battery device according to any one of claims 4 to 6, characterized in that it applies a reverse opening current for a predefined duration of time, or after a predefined number of square pulses or oscillations of this current, or as a function of a limit of the temperature measured on the winding (46).

8. An electric or hybrid motor vehicle comprising a traction battery forming part of a battery system according to any one of of claims 1 to 3, characterized in that the battery is contained in a box (2) containing the safety relay (10).

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