Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
  • H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
  • H02P9/10—Control effected upon generator excitation circuit to reduce harmful effects of overloads or transients, e.g. sudden application of load, sudden removal of load, sudden change of load

Definitions

• the invention relates to the management of the electric current produced in a vehicle, in particular a motor vehicle, this current being intended to supply electrical consumers of this vehicle possibly including a storage battery.
• the number and power of electric consumers equipping motor vehicles are continuously increasing. These consumers are, for example, electric radiators, onboard telematics, electric seats or others.
• the driving of this electric machine affects the torque provided by the engine, and therefore the fuel consumption.
• a power consumption of 300 watts represents a consumption of the order of 0.2 liters per hour, which represents 1 liter per hundred kilometers for use in the city.
• the production of the current is adjusted in real time to correspond to the electrical needs, based on the intensity of the current delivered by the battery to the electrical consumers, and on the state of charge of this battery .
• the alternator is controlled in voltage to deliver an electric power corresponding to a power required by consumers and the battery.
• the load is not favored when the engine is in the acceleration phase, it is instead favored when the engine decelerates. Finally, charging the battery is not performed during engine start.
• This known method thus aims to optimize consumption by keeping the battery in an optimal state of charge while avoiding charging it during critical phases such as starting the engine.
• the object of the invention is to propose a strategy for managing the generation of electric current in the vehicle which makes it possible to further reduce the fuel consumption of the vehicle for the same amount of electric power produced.
• the subject of the invention is a method for controlling the current produced in a motor vehicle including an electric machine driven by a heat engine, such as an alternator, to provide a given average electrical power, in which the machine is controlled to deliver a cyclically varying power between a first determined power to optimize the efficiency or power of the electric machine and a second power lower than the first power, in such variations that the average power corresponds to the average power given.
• the invention also relates to a method as defined above, in which the electric machine is controlled to deliver the first power during a first cycle time and the second power during a second cycle time, and in which the power changes. are controlled according to ramps of rise or fall in power.
• the invention also relates to a method as defined above, wherein the first power is determined to correspond to an optimum performance of the electric machine with respect to its rotational speed.
• the invention also relates to a method as defined above, wherein the second power is determined from the first power to limit the variations of the torque taken by the electric machine on the engine.
• the invention also relates to a method as defined above, wherein the electric machine is connected to a current storage unit, and wherein the first cycle time is determined from the storage capacity of this unit.
• the invention also relates to a method as defined above, comprising a supercapacity as a buffer storage unit, interposed between the electric machine and an electrical consumer power supply edge network of the vehicle.
• the invention also relates to a method as defined above, wherein the electrical machine is voltage controlled to deliver either the first or the second electrical power, and wherein a DC-DC converter is interposed between the supercapacity and the network. on board.
• Figure 1 is a schematic representation of the elements for generating the current in a motor vehicle
• FIG. 2 is a representative graph of the regulation according to the invention.
• FIG. 3 is a map of the efficiency of an alternator as a function of the rotational speed and the delivered current;
• FIG. 4 is a block diagram representation of the control logic according to the invention.
• a motor vehicle comprises a heat engine 1 driving wheels 2 by means of transmission elements marked by 3.
• This heat engine also drives an electric machine 4, such as an alternator, for example via a transmission belt marked by 6.
• This electric machine 4 supplies electrical consumers 9, 11 connected to an on-board vehicle network marked by 7.
• These electrical consumers may include a storage battery marked with 8.
• the electrical machine 4 is driven to deliver an electric power corresponding to the electrical requirement of the electrical consumers connected to the network 7, including in particular the battery 8.
• the electrical power delivered by the electric machine 4 is all the more important that the amount of electrical consumers is high and the battery is lightly charged.
• the electric machine 4 is controlled according to a determined control law to deliver a "chopped" current, according to an overall cycle of several seconds which is shown schematically in FIG.
• This control law consists in first controlling the machine 4 so that it delivers a current corresponding to a first power P1 during a first time interval noted T1, then to deliver a current corresponding to a second power, noted P2 and less than Pl, during a second time interval noted T2.
• the first and the second time T1 and T2 are for example respectively one second and nine seconds. These In particular, the time must be compatible with the reaction time of the electric machine 4 when it is controlled to change the electrical power it delivers. As detailed below, the parameters of the chopped current delivered by the machine 4, namely P1, P2, T1 and T2 are determined in real time.
• the power P1 is first chosen to correspond to an optimum yield range for the machine 4, for the speed of rotation of this machine at the instant in question.
• the rotational speed of the electric machine 4 can thus be determined from a sensor, to determine the power P1. If this speed is for example 10,000 rpm, then the optimum efficiency is obtained for a current delivered equal to 100 Amperes approximately, in accordance with the mapping of FIG. 3. This current intensity delivered corresponds to a certain power that can be determined from other digital data including notably the voltage delivered by the machine 4. The power thus determined is the power Pl , which corresponds to the maximum efficiency of the machine for the considered diet.
• the power P2 is then determined from other criteria, to be as low as possible, while limiting the torque variations induced on the heat engine 1, by the passage of the power Pl to P2 or from P2 to P1 to not very noticeable for the driver.
• the choice of P2 can be made from the value of P1 chosen, using tables of values resulting from tests (maps).
• the power P2 may also simply correspond to a very low general value predetermined or even zero, since it corresponds to a situation in which the efficiency of the electric machine 4 is very low.
• Pl is realized by a rise ramp and by a power reduction ramp to limit the intensity of the torque variations applied to the heat engine 1.
• the duty cycle T1 / (T1 + T2) is then determined so that the average power delivered over a complete cycle, that is to say during a valid time
• T1 + T2 corresponds to the electric power to be supplied to the vehicle.
• This electrical power to be supplied is for example given by an electrical management unit connected to the network and providing a power value representative of the electrical power consumed by the various consumers including the battery, to the moment considered.
• This power Pvec includes the power demanded by the electrical consumers as well as the power possibly requested by the battery 8 for its load.
• T1 and T2 are then determined from the duty cycle and prerecorded data such as the storage capacity of the vehicle battery. These data can also be an overall cycle time T1 + T2 prerecorded in the management unit of the electric machine 4, or a minimum activation time T1 of this predetermined machine 4.
• the electric machine 4 may be a common alternator, controlled in voltage, power, current or torque.
• a voltage-controlled alternator the efficiency of such an alternator tends to favor a low output voltage for the case of a low rotation speed, and a high voltage in the case of a medium rotation speed or Student.
• an additional buffer storage element indicated by 9, is provided between the electric machine 4 and the edge network 7.
• the machine 4 delivers its chopped electrical power into the additional element 9, which is thus suitable supplying the on-board network 7 with a non-chopped continuous current, that is to say not varying cyclically.
• the electric machine delivers a voltage varying over a wide range, such as 12 to 30 volts, and it is operated in association with a storage element 9 which is a supercapacitor, capable of receiving itself a voltage that can vary in a range.
• a storage element 9 which is a supercapacitor, capable of receiving itself a voltage that can vary in a range.
• the machine 4 delivers its chopped electric power into the storage element 9, and a DC-DC converter, indicated by 11, is interposed between the supercapacitance 9 and the network 7, so as to convert the output voltage of the supercapacitor 9 in a voltage corresponding to the nominal value of the on-board vehicle network.
• This converter 11 may comprise a switch for directly feeding one or more electrical consumers from the machine 4, without passing through the supercapacitor 9.
• the invention applies to a vehicle operating in a hybrid mode, in the case where the machine 4 is of the reversible type, that is to say capable of operating as a generator, as seen above, but can also operate as a motor by consuming the electrical energy stored in element 8 or 9 to assist the heat engine 1 in certain situations.
• the management unit determines the current operating mode of the vehicle, based on information such as the speed V of the vehicle, the speed N of its engine 1 , electrical information such as a battery voltage U, an intensity I and a power delivered by this battery, or other information, denoted Inf.
• This operating mode can be, in particular, either “boost”, “generation”, “recharge” or “load shedding”.
• “Boost” mode the machine 4 brings a mechanical torque to the motor by taking electrical energy stored in the supercapacitor 9.
• generation the electric machine 4 takes a mechanical torque from the heat engine 4 to charge supercapacitance 9 and it supplies power consumers free of charge during decelerations.
• “recharge” mode the machine 4 loads the storage element 9, and it supplies the electrical consumers
• the "load shedding” mode the machine 4 produces nothing, and it is the element 9 that feeds the electrical consumers and the battery 8.
• the unit management determines in block B if this generation is done in hash mode. If so, it determines the parameters P1, P2, T1 and T2 in accordance with the indications given above, from the map of this machine, marked by Car in FIG. 4, and information relating to the vehicle such as the speed V and the regime N.
• the management unit controls the machine 4 to generate the current in chopped mode, according to the parameters resulting from block B.
• the management method of the electric machine 4 according to the invention significantly reduces the fuel consumption of the vehicle.
• the optimization of the operating point of the machine thus makes it possible to reduce the average fuel consumption of the vehicle, this strategy being particularly effective in steady state conditions.
• the generation efficiency is 35% with a conventional method, as visible from the mapping of Figure 3.
• the machine is operated to provide 100 amperes for one-fifth of the time, which corresponds to a yield of 55%, as can be seen in FIG.
• the gain in efficiency is 20% at the level of the machine 4.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Electric Propulsion And Braking For Vehicles (AREA)

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• 2006
  • 2006-04-27 FR FR0651501A patent/FR2900516B1/fr not_active Expired - Fee Related
• 2007
  • 2007-04-18 WO PCT/FR2007/051131 patent/WO2007122344A2/fr not_active Ceased
  • 2007-04-18 EP EP07731907A patent/EP2011224A2/de not_active Withdrawn

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