Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
  • H02J7/14—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle
  • H02J7/1423—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from dynamo-electric generators driven at varying speed, e.g. on vehicle with multiple batteries
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
  • H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
  • H02J7/345—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering using capacitors as storage or buffering devices

Definitions

• the present invention relates to a switching unit for a power management device of a consumer network for a motor vehicle and a related method.
• the various electrical equipment of a motor vehicle it is possible to distinguish those which are insensitive to variations in voltage on the consumer network, such as resistive loads such as heated seats, etc., of those which are more sensitive to said variations in voltage.
• the first equipments form the so-called principal network while the second form the so-called secondary network.
• all of these equipment is powered by the vehicle battery.
• some equipment of the secondary network have the particularity of being sensitive to the voltage drops that can occur each time the battery is heavily stressed, for example when starting or restarting the heat engine, especially in the context of a automatic stop / start system commonly called "Stop and Go".
• a secondary battery can be added to the main battery so as to maintain the voltage of the accessories of the secondary network in all circumstances at their nominal operating voltage.
• a known architecture of a power management device of a main network R1 and a secondary network R2 is shown in the diagram of FIG. 1.
• a main battery BAT1, or main storage element is connected to a secondary battery BAT2, or secondary storage element, and a secondary network R2 by a switching unit comprising a diode D and a switch T for connecting or disconnect the BAT2 secondary battery from the power supply provided by the main battery BAT1 via diode D.
• the two main and secondary batteries are conventional lead-acid batteries type VLRA ("Valve Regulated Lead Acid Battery").
• switch T When the vehicle is turned on, switch T is closed.
• the secondary network R2 is then powered by the main battery BAT1 and the secondary battery BAT2, the latter compensating for any drops in the voltage supplied by the first.
• the switch T When the vehicle is stopped, with the ignition off, the switch T is open, otherwise the main battery BAT1 may be discharged into the secondary battery BAT2.
• the secondary network R2 is then powered by the single main battery BAT1. Diode D allows current to flow only from the main battery to the secondary network.
• a solution to the technical problem posed, according to the present invention is that a switching unit which is intended to electrically connect the secondary network with the secondary energy storage element when the vehicle is in a parking mode, in that the secondary energy storage element is a super-capacitor, and in that it comprises means for precharging the secondary energy storage element.
• the secondary network nevertheless remains powered by the super capacitor, this for the duration of the drop in the voltage of the main battery and within the limit of the energy stored in the super capacitor. It should be noted that this function is made possible by the use of a super capacitor that can be completely discharged without degradation, unlike a lead-acid battery that can not withstand discharges and must be systematically disconnected from any consumer to judgment.
• the device according to the invention has the following additional features.
• the switching unit is further intended to electrically connect the secondary network with the secondary energy storage element when the vehicle operates in a generator or engine mode.
• the switching unit is further intended to further electrically connect the secondary network with the secondary energy storage element when the vehicle is operating in an automatic stop / restart mode.
• the precharging means comprise:
• the switching unit further comprises protection means of the secondary network when there is a short circuit on said network.
• the switching unit further comprises a first isolation circuit for isolating the secondary storage element from the main storage element.
• the first isolation circuit includes a first switch.
• the switching unit further comprises a second isolation circuit adapted to isolate the main storage element vis-à-vis the secondary storage element.
• the second isolation circuit includes a second switch.
• the first isolation circuit is placed in series with the second isolation circuit.
• a switch is a unidirectional switch.
• a switch is an electronic switch.
• the switching unit further comprises third means for isolating the main storage element vis-à-vis the secondary storage element.
• the method comprises a step of electrically connecting the secondary network with the storage element.
• secondary energy when the vehicle is in a parking mode, and in that the secondary energy storage element is a super capacitor.
• the invention also relates to a power management device of a consumer network for a motor vehicle comprising a switching unit according to the first object.
• Fig. 2 is a diagram of a first embodiment of a switching unit according to the invention.
• Fig. 3 is a diagram of a second embodiment of a switching unit according to the invention.
• Fig. 4 is a diagram of a third embodiment of a switching unit according to the invention.
• Fig. 5 is a representative curve of a charge / discharge of a super capacitor and a voltage of a main battery, the voltages being used in the previous embodiments.
• FIG. 2 is a first non-limiting embodiment of a power management device of a consumer network for a motor vehicle comprising: a main network R p including in particular the equipment necessary for starting the heat engine, and connected to the rotating electrical machine ALT of the vehicle, here in the example an alternator-starter, a secondary network R 8 mainly comprising accessories, such as a car radio, a clock, etc., a main storage element B p directly connected to the main network R p , a secondary storage element, namely here a supercapacitor U ac p, for supplying the secondary network R 8 , - a switching unit 10 arranged between the battery main B p , the super capacitor U ca p and the secondary network R 8 ,
• a super capacitor is also called ultracapacity or EDLC ("Electric Double Layer Capacitor").
• the power management device also comprises a fuse F which protects the secondary network R 8 if there is a short circuit on said network which causes the passage of too much current.
• the switching unit 10 is arranged between the main battery B p , the super capacitor U ca p and the secondary network R 8 .
• Said unit 10 comprises: - a first and a second diode Di, D 2 whose cathodes are interconnected, said diodes being unidirectional switches, a mechanical switch K in parallel with the first and second diodes Di, D 2 , - a diode D 0 and a precharge resistor R pre in series with the switch K.
• the position of the key in + ACC ON corresponds in particular to a supply of certain accessories such as the car radio or the cigarette lighter in some cases, the position of the key in + APC ON corresponds in particular to a power supply of the whole the onboard network including other accessories and vehicle calculators such as engine control. Note that to arrive in a stop mode of the stop & go system, it must be passed through a position + DEM beforehand to start the engine.
• the device thus illustrated operates in the following manner. • When the vehicle is stopped, in the so-called parking mode or the so-called "parking" mode, ie when the ignition is switched off (main power is off and the engine has stopped), the switch K is open.
• the secondary network R 8 is powered by the highest voltage supplied by the main battery B p and the supercapacitor U ca respectively by diodes Di and D 2 . It can be seen that, if the voltage supplied by the main battery B p drops at a standstill, the secondary network R 8 always remains powered by the supercapacitor U ca p, which can occur in case of disconnection of the main battery B p for maintenance, for example.
• the switch K isolates the main storage element B p vis-à-vis the secondary storage element U ca p, especially when the secondary storage element is short-circuited. This prevents the main battery B p from being discharged into the supercapacitor U ca. • As soon as the ignition is switched on (ignition key in position + ACC ON) and therefore in motor mode, switch K is brought to the closed position. In this case, the battery B supplies the p supercapacitor U ca p by means of the diode D 0 and the precharge resistor R pre, which limits the charging current particularly during the first connection.
• the secondary network R 8 is powered by the highest voltage supplied by the main battery B p and the supercapacitor U ca p via the diodes Di and D 2 .
• Fig. 5 illustrates the voltage U p of the main battery B p and the voltage U c of the supercapacitor U ca.
• the periods of charge and discharge of the supercapacitor can be seen. Moreover, one can see that during the periods t1 and t3, the secondary network R 8 is powered by the main battery Bp, while during the periods t2 and t3 the secondary network R 8 is supplied by the supercapacitor U cap.
• switch K In case of engine stop and automatic start in "Stop and Go" mode, switch K is always closed.
• the secondary network R 8 is powered by the highest voltage supplied by the main battery B p and the supercapacitor U cap as illustrated in FIG. 5 as seen previously.
• the diode D 0 as well as the first diode Di make it possible to provide the protection function against voltage drops. It avoids the discharge of the super capacitor in the main battery B p when the latter is out of service for example or disconnected for maintenance. Moreover, the second diode D 2 prevents the main battery B p from being discharged into the super capacitance U cap if, for example, the super capacitor is short-circuited. In conclusion, with this device, there is no risk related to under load unless the main battery and the super capacitor are both discharged.
• Fig. 3 illustrates a second non-limiting embodiment in which the switching unit 10 is also arranged between the main battery B p , the super capacitor U ca p and the secondary network R 8 .
• Said unit 10 comprises: a first isolation circuit comprising a first diode Di and an electronic switch Mi; this first isolation circuit makes it possible in particular to isolate the super capacitor U ca p vis-à-vis the main storage element B p ; a second isolation circuit comprising a second diode D 2 and an electronic switch M 2 , the two diodes Di and D 2 being connected by their cathode.
• the first and second isolation circuits are for example MOSFET transistors whose drains are connected; this second isolation circuit allows in particular to isolate the main storage element B p vis-à-vis the super capacitor U ca p; this second isolation circuit is associated in series with the first isolation circuit;
• a fuse F the secondary network R 8 being fed through this fuse F at the midpoint between the two isolation circuits, a diode D 0 and a precharge resistor Rp re in parallel with the first and second circuits of isolation.
• the precharging resistor Rp re makes it possible to charge the supercapacitor U ca p (which makes it possible to limit the current flowing through the MOSFET transistors at the start of the order of 30A instead of 80A), whereas the diode D 0 to provide the protection function against voltage drops; it avoids the discharge of the super capacitor in the main battery B p when the latter is out of service for example and especially during startup, the startup being part of the engine mode.
• One of the advantages of the device of FIG. 3 is to use electronic switches Mi, M 2 , made for example by MOS transistors on an electronic card, instead of mechanical switches. This allows in particular to have a lifetime of the upper switches (at least a factor of 10).
• the device of FIG. 3 works in the following manner.
• the secondary network R 8 is powered by the main battery B p (at the voltage drop of the first diode Di near, generally 0.7V for a conventional diode) and by the supercapacitor U ca p (at the voltage drop of the second diode D 2 near) respectively via the first diode Di and via the second diode D 2 and more particularly by the element which has the highest voltage as shown in FIG. 5 as seen previously.
• the secondary network R 8 is always powered by the supercapacitor U ca p- Moreover, it does not discharge into the main network R p through the first diode Di and the diode D 0 .
• the secondary network R 8 is powered by the main battery B p (at the voltage drop of the first diode Di near, usually 0.7V for a conventional diode) and the super capacitor U ca p respectively via the first diode Di and via the second switch M2 and more particularly by the element which has the highest voltage as seen above. In this case, it can be seen that the voltage drop of the second diode D 2 no longer counts in the supply by the supercapacitor U cap . Thus, said power supply is more efficient.
• a voltage drop Up can occur if a large consumer is switched on, for example power steering or air conditioning, and of course at startup without there being a discharge of the super capacitor U ca p in the main network R p and thanks to the first diode Di and the diode D 0 .
• the secondary network is always powered by the supercapacitor U ca p via the second transistor M2.
• the Mi and M 2 switches are closed.
• the super capacitor U ca p is directly connected to the main network R p via the switches M1 and M2 and is charged by means of the main battery B p .
• the super capacitor U ca p continues to filter the voltage ripples in the secondary network R 8 .
• the secondary network R 8 is powered by the highest voltage supplied by the main battery Bp or the super capacitor U cap as seen above. It is no longer fed through the isolation diodes Di and D 2 of the MOS switches, the voltage drop associated with these diodes is no longer involved, unlike the case of the stationary vehicle. Thus, there are less joules losses than with the diodes.
• a problem of this second embodiment is that at a standstill if a short circuit occurred at the super capacitor U cap , the main battery B p which at rest is still connected to the super capacitor would discharge quickly into the secondary network R 8 via the diode D 0 . As a result, the secondary network R 8 would quickly cease to be powered.
• Fig. 4 illustrates a third non-limiting embodiment which incorporates for the switching unit 10 the same architecture as the third embodiment without the diode D 0 and the pre-load resistor Rp re .
• An advantage of this device is that, when stopped, the main battery B p is isolated vis-à-vis the supercapacitor U cap , which avoids any discharge of the battery if the super capacitor U cap entered into short- circuit.
• the device of FIG. 4 operates in the following manner. • When stopped, in "parking" mode, ie when the ignition is off, the switches Mi and M 2 are open.
• the secondary network R 8 is powered by the highest voltage supplied by the main battery B p (at the voltage drop across the first diode Di near) and the supercapacitor U ca p (at the voltage drop across the terminals). of the second diode D 2 ) via respectively the first diode Di and the second diode D 2 as illustrated in FIG. 5 as seen previously.
• the secondary network R 8 is always powered by the super capacitor U ca.
• the latter does not discharge into the main network R p thanks to the diode Di, same as the main battery B p can not be discharged into the secondary network thanks to the diode D 2 if a short circuit occurred at the supercapacitor U ca p-
• switch M 1 As soon as the ignition is switched on (ie in the + ACC ON position) and thus in the motor mode, switch M 1 remains open and switch M 2 is closed.
• the secondary network R 8 is powered by the highest voltage supplied by the main battery B p (at the voltage drop across the first diode D 1 , in general 0.7V for a conventional isolation diode) and the super capacitor U CaP respectively via the first diode D 1 and via the switch M 2 as illustrated in FIG. 5. If the voltage supplied by the main battery B p is greater than that of the super capacitor U ca p, the latter is charged through the switch M 2 and the first isolation diode D 1 .
• the discharge of the supercapacitor in the main network R p is avoided thanks to the first isolation diode D 1 .
• the closing of the switch M 2 is controlled to ensure the precharging.
• the second electronic switch M 2 can be controlled as a load current limiter by controlling its opening, so as to progressively charge the supercapacitor U ca. This avoids having a high inrush current (8OA in general or more depending on the super capacitor) which may degrade or even destroy said storage U CA p during its first connection when it is fully discharged. This limits the charge current of the super capacitor.
• the switch M 2 is open until the current is canceled and closed again, this for a predetermined period, for example for 2 seconds, time amply sufficient to charge the super capacitor. If the current value still remains higher than this maximum value of 30A after this time, the switch M 2 is kept open and a fault is diagnosed, probably due to a short circuit in the super capacitor U cap .
• This control in current limitation is preferably all the time active as soon as the network is energized.
• the supercapacitor U ca p is directly connected to the main network R p via its switches and is charged by means of the main battery B p . When charged, the super capacitor continues to filter the voltage ripples in the secondary network R 8 .
• the secondary network R 8 is powered by the highest voltage supplied by the main battery B p or the supercapacitor U ac as shown in FIG. 5. It is no longer supplied through isolation diodes Di and D 2 of the MOS switches, the voltage drop associated with these diodes is no longer involved, unlike in the case of the stationary vehicle.
• the interest to do during the rolling period is to diagnose a short circuit on the super capacitor U cap . Indeed, during a short circuit, there is a strong current, at this time the control in current limitation occurs. As after two seconds, the current is still too strong, the switch M 2 is kept open and the fault is diagnosed as seen above. • During an automatic shutdown then an automatic start (system "Stop &Go"), at the end of the generator mode, the switches M1 and M2 are respectively open and closed (M2 is always closed when there is not a strong current detected).
• the secondary network R 8 is powered by both the main battery B p and the supercapacitor U ac p respectively via the first isolation diode Di and the second switch M2.
• the first isolation circuit operates in a perfect diode.
• the diode Di and the switch M1 of the first isolation circuit of the switching unit 10 are replaced by a so-called perfect diode having a very low voltage drop, of the order of 0.01 V.
• Such a diode can be realized by a MOS transistor driven in perfect diode.
• the advantage is that the voltage drop due to the isolation diode Di is avoided, resulting in fewer losses in line to supply the secondary network R 8 or charge the supercapacitor U ca p- Supercapacitor filtering voltage ripple is much more efficient because it avoids the voltage drop of 0.07V.
• This operation is used in a perfect diode when the vehicle is energized (power-up, start-motor mode or generator mode). It will be noted that, preferably, the perfect diode function is always active as soon as the power is turned on. Thus, the switching unit does not limit the recharging capabilities of the super capacitor. Thus, this does not ultimately lead to a degradation of this energy store contrary to the prior art.
• the use of a perfect diode as a switch improves the performance of the system in terms of efficiency (unlike a conventional diode) and thus allows improved management of the secondary battery charge, here the super capacitor.
• the device according to the invention has many other advantages which are the following.
• the charge of the secondary storage element is better with a super capacitor than with a lead-acid battery.
• the charging voltage imposed by the alternator-starter ALT in generator mode is determined, as a rule, to optimize the charge of the main battery B p which is at a temperature T B.
• T B the charging voltage
• T s the temperature of the secondary battery B 8 which, on the other hand, is at a temperature T s different from T B
• the main battery and the secondary battery being generally in two different places, the one under the bonnet and the other under a seat.
• the charge of the secondary battery is therefore not optimized with the risk of underload and degradation due to loss of capacity. This disadvantage disappears completely with a super capacitor whose life is not affected by a state of charge storage less than 100%.
• the super capacitor makes it possible to filter the ripples and other disturbances of the current generated by the alternator-starter ALT in generator mode. This results in a more stable supply voltage of the secondary network and therefore less stress on its components.
• the energy stored in the super capacitor can also be used to power safety components, such as safety cushions, belt pre-tensioners, door opening systems, battery disconnect systems, etc., even when the main battery is no longer available, especially in the event of an accident (battery disconnected or short-circuited) or short-circuit on the main network.
• the super capacitor can power the controllers of the vehicle, or the security code of the car radio, thus avoiding any loss of stored data.
• the life of a super capacitor is longer than that of the vehicle. There is no need for a replacement, so with an average life of three years, a lead-acid battery needs to be replaced about three times.
• a super capacitor has a smaller volume and weight than a conventional lead-acid battery.
• any other secondary energy storage element may be used, such an element may preferably be completely discharged without degradation such as a super capacitor.
• a vehicle that uses a key contact there is described a vehicle that uses a key contact, but this invention also applies to any vehicle that uses a contact card.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Charge And Discharge Circuits For Batteries Or The Like (AREA)
• Electric Propulsion And Braking For Vehicles (AREA)

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• 2005
  • 2005-11-24 FR FR0511890A patent/FR2893770B1/fr not_active Expired - Fee Related
• 2006
  • 2006-10-27 EP EP06831312A patent/EP1951553A2/de not_active Withdrawn
  • 2006-10-27 WO PCT/FR2006/051120 patent/WO2007060348A2/fr active Application Filing
  • 2006-10-27 US US12/090,441 patent/US7800244B2/en not_active Expired - Fee Related

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