SYSTEM FOR SUPPLYING ELECTRIC POWER TO THE ELECTRICAL EQUIPMENT OF A MOTOR VEHICLE BY A HIGH-PERFORMANCE BATTERY, CORRESPONDING CURRENT LIMITATION DEVICE AND STARTER PROVIDED

Abstract

The invention relates to a system for supplying electric power (10) to electrical equipment via a high-performance battery (2) comprising at least one device (LPF) for limiting a current of the high-performance battery. The high-performance battery has a first nominal voltage greater than that of a standard battery initially provided for supplying the equipment, which include an internal combustion engine starter (8) that is connected to the high-performance battery via the limiting device. According to the invention, the limiting device (LPF) is a transformer having a secondary winding circuit (R, W2) formed by a short-circuited secondary winding (W2). According to another feature, the coupling coefficient of the transformer and a secondary resistance of the secondary winding circuit are dependent on the specific characteristics of the equipment.

Claims

1. System (1, 10, 11) for supplying electric power to the electrical equipment (6, 8, 9, 12) of a motor vehicle by a so-called high-performance battery (2) of the type comprising at least one limitation device (7, LPF), in order to limit a current of said high-performance battery (2), with a first nominal voltage, in order to satisfy characteristics of said equipment (6, 8, 9, 12) initially designed to be connected to a so-called standard battery, with a second nominal voltage lower than said first nominal voltage, said equipment (6, 8, 9, 12) comprising at least one starter (8) of a thermal engine of said vehicle, connected to said high-performance battery (2) by a power circuit comprising said at least one limitation device (7, LPF) fitted in series with said starter (8), wherein said at least one limitation device (LPF) is a transformer comprising a secondary winding circuit (R, W2) formed by a short-circuited secondary winding (W2).

2. System (10, 11) for supplying electric power to the electrical equipment (6, 8, 9, 12) of a motor vehicle by a so-called high-performance battery (2) according to claim 1, wherein said transformer (LPF) has a coupling coefficient and a secondary resistance (R) of said secondary winding circuit (R, W2) which depend on said characteristics.

3. System (10, 11) for supplying electric power to the electrical equipment (6, 8, 9, 12) of a motor vehicle by a so-called high-performance battery (2) according to claim 1, wherein a primary winding (W1) of said transformer (LPF) is inserted between a power contact (CP) of an electromagnetic contactor (EC), and an electric motor (DCM) of said starter (EC, DCM).

4. System (10, 11) for supplying electric power to the electrical equipment (6, 8, 9, 12) of a motor vehicle by a so-called high-performance battery (2) according to claim 1, wherein said equipment (6, 8, 9, 12) comprises a plurality of electric motors (M1, M2, M3) each connected by a contactor (S1, S2, S3) and by a so-called limitation device (LPF) to an on-board network which is supplied by said high-performance battery (2).

5. System (10, 11) for supplying electric power to the electrical equipment (6, 8, 9, 12) of a motor vehicle by a so-called high-performance battery (2) according to claim 4, wherein said equipment (6, 8, 9, 12) additionally comprises at least one element of a group comprising at least one electric windscreen wiper, at least one at least one electric power window, at least one electric windscreen washer, at least one electric fan, at least one electric compressor, and at least one electric lock.

6. System (10, 11) for supplying electric power to the electrical equipment (6, 8, 9, 12) of a motor vehicle by a so-called high-performance battery (2) according to claim 1, wherein said high-performance battery (2) is of the lithium-ion type with a first nominal voltage of approximately 13.4 V, and said standard battery is of the lead-acid type with a second nominal voltage of approximately 12.8 V.

7. Device (LPF) for limitation of the current of a high-performance battery (2) which can be used in the system (10, 11) for supplying electric power to the electrical equipment (6, 8, 9, 12) of a motor vehicle by a so-called high-performance battery (2) according to claim 1, comprising a magnetic circuit (YO, C, CM, CM) formed by a casing (YO, C) made of magnetic material comprising a cylindrical head (YO), two closure parts (CM, CM), and an axial core (C) around which a primary winding (W1) and a short-circuited secondary winding (W2) are arranged.

8. Device (LPF) for limitation of the current of a high-performance battery (2) according to claim 7, wherein said secondary winding (W2) is formed by an electrically conductive tube which surrounds said primary winding (W1), and has a ratio of length to radius which is predetermined according to specific characteristics of one of the items of electrical equipment (6, 8, 9, 12) for which said limitation device is designed.

9. Combination (13) in a motor vehicle of a starter (DCM, EC) comprising an electric motor (DCM) and an electromagnetic contactor (EC), a high-performance battery (2) of the lithium-ion type, and a device (LPF) for limitation of the current of said high-performance battery (2) according to claim 7.

10. Combination (13) according to claim 9, wherein said limitation device (LPF) is secured on an outer housing (14) of said starter (DCM, EC), and wherein said electric motor (DCM) is a standard motor which is designed to be supplied with power by a standard battery of the lead-acid type.

11. System (10, 11) for supplying electric power to the electrical equipment (6, 8, 9, 12) of a motor vehicle by a so-called high-performance battery (2) according to claim 2, wherein a primary winding (W1) of said transformer (LPF) is inserted between a power contact (CP) of an electromagnetic contactor (EC), and an electric motor (DCM) of said starter (EC, DCM).

12. System (10, 11) for supplying electric power to the electrical equipment (6, 8, 9, 12) of a motor vehicle by a so-called high-performance battery (2) according to claim 2, wherein said equipment (6, 8, 9, 12) comprises a plurality of electric motors (M1, M2, M3) each connected by a contactor (S1, S2, S3) and by a so-called limitation device (LPF) to an on-board network which is supplied by said high-performance battery (2).

13. System (10, 11) for supplying electric power to the electrical equipment (6, 8, 9, 12) of a motor vehicle by a so-called high-performance battery (2) according to claim 2, wherein said high-performance battery (2) is of the lithium-ion type with a first nominal voltage of approximately 13.4 V, and said standard battery is of the lead-acid type with a second nominal voltage of approximately 12.8 V.

14. System (10, 11) for supplying electric power to the electrical equipment (6, 8, 9, 12) of a motor vehicle by a so-called high-performance battery (2) according to claim 3, wherein said high-performance battery (2) is of the lithium-ion type with a first nominal voltage of approximately 13.4 V, and said standard battery is of the lead-acid type with a second nominal voltage of approximately 12.8 V.

15. System (10, 11) for supplying electric power to the electrical equipment (6, 8, 9, 12) of a motor vehicle by a so-called high-performance battery (2) according to claim 4, wherein said high-performance battery (2) is of the lithium-ion type with a first nominal voltage of approximately 13.4 V, and said standard battery is of the lead-acid type with a second nominal voltage of approximately 12.8 V.

16. System (10, 11) for supplying electric power to the electrical equipment (6, 8, 9, 12) of a motor vehicle by a so-called high-performance battery (2) according to claim 5, wherein said high-performance battery (2) is of the lithium-ion type with a first nominal voltage of approximately 13.4 V, and said standard battery is of the lead-acid type with a second nominal voltage of approximately 12.8 V.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG. 1 is a process diagram of a system for supplying electric power to the electrical equipment of a motor vehicle by a battery of the lithium-ion type known in the prior art.

[0039] FIG. 2 is a process diagram of a system for supplying electric power to the electrical equipment of a motor vehicle, in particular a starter, by a battery of the lithium-ion type according to the invention.

[0040] FIG. 3 is a process diagram of a system for supplying electric power to the electrical equipment of a motor vehicle, in particular a starter, and several other items of equipment comprising electric motors, by a battery of the lithium-ion type according to the invention.

[0041] FIG. 4 shows in axial cross-section an embodiment of a current limitation device of a high-performance battery, which device can be used in the system for supplying electric power to the electrical equipment of a motor vehicle, by a high-performance battery according to the process diagrams shown in FIGS. 2 and 3.

[0042] FIG. 5 is a schematic view showing a combination of a battery of the lithium-ion type, a standard starter, and a current limitation device of a high-performance battery according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0043] In the system 1 for supplying electric power to the electrical equipment of a motor vehicle known in the prior art represented in FIG. 1, a battery 2 with lithium-iron-phosphate (LiFePO.sub.4) technology comprises a negative terminal 3 leading to an earth 4, and a positive terminal 5 which is connected to an on-board network 6 of the vehicle.

[0044] The positive terminal 5 of this battery 2 is also connected by an electrical circuit 7 to an electric motor DCM of a starter 8 of the thermal engine of the vehicle, and to an alternator 9 which is driven by this thermal engine.

[0045] The electrical circuit 7 comprises, between the positive terminal 5 of the battery 2 and the starter 8, a first connection comprising a first resistor R1 with a low value of approximately 1 m, arranged in series with a first switch K1, and a second connection comprising a second resistor R2 of approximately 6 m, arranged in series with a second switch K2.

[0046] The electrical circuit 7 comprises, between the positive terminal 5 of the battery 2 and the alternator 9, a third connection comprising only a third switch K3, and a fourth connection comprising another resistor R2, also of approximately 6 m, arranged in series with another switch K2.

[0047] The switches K1, K2, K3, K2 are controlled by control and command electronics which receive various information on the running of the vehicle and the actions of the driver.

[0048] For the starting of the thermal engine using the starter 8, the second switch K2 is closed, which makes it possible to lower a first nominal voltage of approximately 13.4 V supplied by the battery 2, to a second nominal voltage 12.8 V which is compatible with the characteristics of an electric motor 8 of a starter, designed to be connected to a standard battery of the lead-acid type.

[0049] Exceptionally, in difficult starting conditions, the first switch K1 is closed in order to supply the starter with a higher voltage.

[0050] Similarly, the third and fourth switches K2, K3 are controlled according to the state of charge of the battery 2.

[0051] As already indicated in the preamble, this system 1 for supplying electric power to the electrical equipment of a motor vehicle known in the prior art is not satisfactory, since valuable electrical energy is dissipated to no advantage by Joule effect in the electrical circuit 7.

[0052] This is even more unsatisfactory if the electrical supply system 1 is used in an automatic stopping/restarting system, where restarting operations are very frequent in urban traffic.

[0053] In the system 10 for supplying electric power to the electrical equipment of a motor vehicle according to the invention represented in FIG. 2, instantaneous power consumed by the electric motor DCM of the starter is limited by a device LPF for limitation of the current supplied by the lithium-iron battery 2, but the electrical energy is recuperated at least partly as a result of the inductive nature of this device LPF.

[0054] The limitation device LPF is inserted in a power circuit of the starter EC, DCM, in series between the electric motor DCM and a power contact CP of the electromagnetic contactor EC.

[0055] In this case, the contactor EC is a conventional starter contactor with a simple power contact CP, and comprises a solenoid formed by a pull-in coil and a hold-in coil.

[0056] Closure of a starter contact CS of the vehicle commands the excitation of the pull-in and hold-in coils, and activation of the starter DCM, EC, according to a sequence which is well-known by persons skilled in the art, and will not be described in detail here.

[0057] The strong initial current spike previously mentioned intervenes at the closure of the power contact CP, when the motor DCM is supplied with full power.

[0058] Closure of the power contact CP also gives rise to circulation in the limitation device LPF of a power current which supplies power to the motor DCM.

[0059] As shown in its wiring diagram in FIG. 2, the limitation device LPF is a transformer of the armoured type with windings W1, W2 which are coupled magnetically, and a secondary winding circuit W2, R, formed by a secondary winding W2, the ends of which are connected directly to one another, i.e. which is short-circuited.

[0060] Various embodiments of this transformer LPF make it possible to have several parameters in order to adjust the pulse response of the limitation device LPF, according to the specific characteristics of the electric motor DCM of the starter. Thus, it is possible to optimise this response by regulating inductances of the primary and secondary windings W1, W2, by mutual inductance introduced by coupling between these circuits, and by a secondary resistor of the secondary winding circuit R, W2 represented in FIG. 2 by an equivalent resistor R.

[0061] However, the transformer LPF continues to be a high-quality transformer, i.e. it is selected so as to have a coupling coefficient close to a unit.

[0062] It will be remembered that the coupling coefficient of a transformer is defined by the ratio k=M/(L.sub.1.Math.L.sub.2).sup.1/2, where M is a mutual inductance, L.sub.1 is the primary inductance, and L.sub.2 is the secondary inductance.

[0063] The primary winding circuit W1 is the one which is inserted in the power circuit of the starter.

[0064] Typically, an equivalent inductance of the limitation device LPF is between 0.1 and 10 mH approximately for power currents with an order of magnitude of 300 to 1000 A.

[0065] The effect of limitation of the instantaneous power is derived from the fact that when power is supplied to the motor DCM by the lithium-ion battery 2, the initial current spike is attenuated by approximately half despite a supply voltage which is higher than that supplied by a standard lead battery, because of the production of strong induced currents in the short-circuited secondary circuit W2, which opposes the sudden variation of magnetic flux which generates them.

[0066] Slow development of the power current at the moment when power is supplied to the motor DCM limits the risks of electrical damage to the brush-collector contacts of the motor DCM, and attenuation of the initial current spike limits the risks of mechanical damage caused by an associated excessively high level of torque.

[0067] In the system 11 for supplying electric power to the electrical equipment of a motor vehicle according to the invention represented in FIG. 3, electric motors M1, M2, M3 of equipment 12 designed to function with a standard 12 V battery are put into operation by switches S1, S2, S3, by connecting them to the lithium-ion battery 2.

[0068] Current limiters LPF1, LPF2, LPF3 according to the invention, of the same type as the one previously described, formed by transformers with a short-circuited secondary, are inserted in series with these electric motors M1, M2, M3.

[0069] These transformers are adapted to the characteristics of the equipment, which can be an electric windscreen wiper, an electric power window, an electric windscreen washer, an electric fan, an electric compressor, or an electric lock.

[0070] An example of a specific embodiment of the current limitation devices LPF, LPF1, LPF2, LPF3 is shown in FIG. 4.

[0071] In the example in FIG. 4, the transformer LPF substantially comprises a casing C, YO, CM, CM made of magnetic material such as steel, and primary W1 and secondary W2 windings.

[0072] The casing comprises a cylindrical head YO, two closure parts CM. CM and an axial core C, around which the primary and secondary windings W1, W2 are arranged.

[0073] The primary winding W1 is designed to be inserted in series in the power circuit DCM, EC, and the secondary winding W2 is short-circuited.

[0074] This secondary winding W2, which surrounds the primary winding W1, comprises a plurality of turns, or alternatively it is produced in the form of an electrically conductive tube.

[0075] In an embodiment in the form of a tube, the latter has a ratio of length to radius which is predetermined according to specific characteristics of the equipment for which the limitation device LPF is designed.

[0076] FIG. 5 shows schematically a specific application of a limitation device LPF according to the invention in a motor vehicle.

[0077] The application presented relates to a combination 13 of:

[0078] a lithium-ion battery 2 of a 12 V 50 Ah model;

[0079] a starter DCM, EC comprising a direct current electric motor DCM and an electromagnetic contactor EC designed for use with a standard 12 V lead-acid battery;

[0080] a current limitation device LPF as previously described.

[0081] In this application, the current limitation device LPF is secured mechanically on an exterior housing 14 of the electric motor DCM of the starter, in the vicinity of the contactor EC.

[0082] The electrical connections between the current limitation device LPF, the contactor EC and the electric motor DCM correspond to the process diagram shown in FIG. 2.

[0083] The current limitation device LPF according to the invention is an entirely passive device which does not need any complex control logic, necessarily generating substantial additional costs, unlike the electrical circuit 7 formed by switchable resistors R1, R2, R2 known in the prior art, as shown in FIG. 1.

[0084] Since the current limitation is not based on the insertion of resistors R1, R2, R2, nor are there associated losses by Joule effect, and the electrical performance of the supply system 10, 11 is maintained.

[0085] It will be appreciated that the invention is not limited simply to the above-described preferred embodiments. Also, the equipment cited consists only of non-limiting examples: any equipment of the vehicle which constitutes an inductive or capacitive load which can give rise to a high requirement for current when power is supplied to it can be protected by the current limitation device LPF according to the invention.

[0086] The high-performance battery 2 cited is a battery of the lithium-ion type with iron-phosphate technology. A battery 2 with iron-phosphate technology doped with yttrium (LiFeYPO.sub.4) operating at lower negative temperatures (down to 35 C.) could equally well be implemented in the electrical supply system 10, 11 according to the invention, as well as batteries with other technologies such as lithium-cobalt oxide (LiCoO.sub.2), lithium-manganese oxide (LiMn.sub.2O.sub.4), lithium-nickel-manganese-cobalt oxide (LiNiMnCoO.sub.2), lithium-nickel-manganese-aluminium oxide (LiNiMnAlO.sub.2), lithium-titanate (Li.sub.4Ti.sub.5O.sub.12, with five elements in series).

[0087] High-performance batteries of the lithium-polymer (LiPo) type can also be envisaged for motor vehicle applications. With a voltage per element of 3.7 V, they differ little from iron-phosphate batteries with a voltage per element of 3.6 V. Thanks to the present invention, a standard 12 V lead battery could also be replaced in a vehicle by a LiPo battery 2 with four elements, without damage to the equipment.

[0088] The invention thus incorporates all possible variant embodiments, within the limits of the subject of the following claims.