FR2933357A1 - Electrical power supply system managing method for hybrid vehicle, involves configuring management unit such that switch is controlled in open position during life situation such as starting of heat engine - Google Patents

Abstract

The method involves managing an open position or closed position of a switch connected to electrical networks using a managing unit. The managing unit is configured such that the switch is controlled in the open position during life situation such as starting of a vehicle heat engine by an alterno-starter of a stop and start system. The switch has a control input for setting the switch in closed position for electrically connecting the electrical networks or in open position for isolating the electrical networks. An independent claim is also included for a device for managing an electrical power supply system of a hybrid vehicle.

Description

MULTI VOLTAGE POWER MANAGEMENT SYSTEM FOR HYBRID VEHICLE

The invention relates to vehicles of the type comprising a drivetrain power train (or GMP) with a heat engine coupled to the wheels of the vehicle via a clutch and a gearbox and an electric machine for be coupled with audite wheels of the vehicle.

The invention relates more particularly to vehicles with a 1 o parallel hybrid traction comprising a Stop and Start system.

The Stop and Start system will stop the engine just before and during the vehicle standstill. The restarting of the engine is automatic, for example when releasing the brake pedal when the driver wishes to restart. For this purpose, the device comprises a reversible alternator configured, either as an electric generator, when it is driven by the heat engine supplying an electric current to the vehicle networks, or as an electric motor to start the starting of the engine. Fig. 1 shows a state-of-the-art hybrid traction vehicle equipped with a Stop and Start system. The vehicle of FIG. 1 comprises a heat engine MTH 10 coupled, via a clutch 12, a gearbox 14 and a gear-reduction bridge 16, to a gear train 18 comprising two drive wheels 20, 22 for the traction of the vehicle. The vehicle of FIG. 1 further comprises an electric machine 30 mechanically coupled to the drive wheels 20, 22 by said gearbox 14, an electrical energy storage device 32. A Stop and Start system 36 automatically performs the stopping and restarting the engine 10. In a first life situation, the vehicle is powered exclusively by the MTH engine. The drive wheels 20, 22 receive a driving torque of the engine. The electric machine 30, configured as a generator, is rotated by the heat engine MTH to provide a charging electric current by means of electrical storage 32, a low voltage battery BT for example. In a second life situation, the vehicle is powered exclusively by the electric machine 30, the heat engine MTH is stopped. The gearbox 14 receives a motor torque supplied by the electrical machine 30 powered by the electrical energy stored in the electrical storage means 32. Other configurations are possible, for example, the motor 1o thermal MTH and the electric machine 30 can each provide a motor torque. Torques are then summed in the gearbox 14 to drive the drive wheels 20, 22 of the vehicle.

FIG. 2 shows an electrical architecture of the parallel hybrid vehicle of FIG. 1 comprising a switch connecting two electrical networks of the vehicle. The electrical architecture of FIG. 2 essentially comprises a first R1 and a second R2 electrical network electrically connected by an Int switch having two terminals A and B. The switch is connected by an A of these two terminals to the first network. R1 and the other terminal B to the second electrical network R2. The switch Int comprises a control input Ec to be put either in the closed position to electrically connect the two networks R1 and R2, or in the open position to isolate the two networks. First electrical elements are connected to the first electrical network R1. and second electrical elements are connected to the second electrical network R2. The first electrical elements, connected to the first network R1, comprise a battery BT 40 with 12 volts of voltage to supply, through a first protection and distribution box BPD 42, first auxiliary electrical elements AUX NS 44 of the vehicle which is not very sensitive. the variations of the supply voltage, an automatic stop and start device of the Stop and Start STT heat engine comprising an alternator-starter 46 powered by an OND STT inverter 48 35 from the first DC electrical network R1.

A mechanical coupling device 50 between a drive shaft 52 of the engine MTH 10 and the Stop and Start system provides, on the one hand, the launch of the engine MTH and, on the other hand, the load by the alternator-starter of the battery BT 40 of 12volts.

The second electrical elements, connected to the second network R2, comprise a DC / DC converter 60 supplying an electrical current to the networks R1, R2 from a high voltage battery BT HT 62 intended to power an electric machine ME 64 of the hybrid vehicle through a power inverter 66, second auxiliary electric auxiliary elements AUX SE 70 of the vehicle, responsive to variations in the supply voltage, supplied through a second protection and distribution box BPD 72. The electrical architecture of FIG. FIG. 1 makes it possible to ensure the running of the vehicle in pure electric mode, that is to say without assistance of the thermal engine MTH 10 which is at a standstill. In this life situation in pure electric mode, the Stop and Start STT system does not supply power to the R1, R2 power grids. The alternator 46 of the Stop and Start system is not driven by the MTH engine 10 stopped. In this configuration, the auxiliary electric elements of the vehicle must be powered either by the battery BT of the first network R1, or by the DC / DC converter 60 of the second network R2 pumping energy on the high voltage battery BT HT In order to provide the electric current required for the vehicle in this life configuration, on the one hand, the DC / DC converter 60 must be sufficiently sized (or powerful) to be able to supply the two low voltage electrical networks R1, R2 with the disadvantages that this implies in terms of weight, cost and space and on the other hand, low voltage battery BT 40, typically 12 volts, must have sufficient capacity to power the two electrical networks R1, R2 low voltage of vehicle with the same disadvantages of weight, cost and size. Another life situation of the hybrid vehicle, based on the electrical architecture of FIG. 2, is the starting of the engine 35 MTH 10 by the starter-alternator 46 of the Stop and Start system. In this life situation, the start of the heat engine MTH is performed by the power supply, from the battery BT 40, of the starter-alternator 46 of the Stop and Start system. The high power consumption of the alternator-starter 46 produces very large voltage fluctuations at the terminals of the battery BT 40 which causes, for example, variations in the illumination of the headlights or other lighting elements or lights of the vehicle . In addition, the torque that can be provided by the starter-alternator 46 to launch the MTH engine 10 of the vehicle is limited by the power level 1 o available from the battery BT 40 12 volts.

To overcome the drawbacks of state-of-the-art hybrid vehicles, the invention proposes a method for managing a hybrid vehicle power supply system that can operate according to different life situations, the hybrid vehicle comprising: a powertrain power train having a heat engine coupled to the vehicle wheels via a clutch and a gearbox, an electric machine mechanically coupled through said gearbox to the wheels of the vehicle, a first electrical network connecting at least: a first energy storage device, an alternator / starter that can be configured either as a starter for launching the heat engine, or as a current generator, and first auxiliary electrical elements of the vehicle can 25 responsive to variations in electrical supply voltage, - a second energy storage device electrical power supply for supplying at least the electrical machine; a second electrical network connected on the one hand to a DC output DC / DC powered by the second electric energy storage device and connected, on the other hand, to second auxiliary electric components of the vehicle responsive to variations in electrical supply voltage, - a switch having two terminals; the switch being connected by one of these two terminals to the first electrical network and the other terminal to the second electrical network, the switch further comprising a control input to be put in the closed position to electrically connect the two networks, either in open position to isolate the two networks, - management means for managing the open or closed position of the switch, characterized in that the management means for managing the position of the switch, are configured from so that the switch is controlled in the open position, for at least one time of the operating life situation of the vehicle.

1 o Advantageously, the alternator-starter being configured as a starter, the method consists in putting the switch by the management means in the open position during the supply of the alternator-starter for launching the heat engine, so to avoid voltage variations, by overloading the second electrical network, on the second auxiliary electric elements of the vehicle responsive to variations in electrical supply voltages.

In one embodiment of the method, the heat engine being in operation, the method consists of putting the switch by the management means in the open position to recharge the first energy storage device only by the first electrical network of the vehicle, in order to to limit the operation of the alternator-starter in alternator mode.

In another embodiment of the method, the two electrical networks 25 being isolated, the low voltage battery is charged by the alternator-starter configured as a generator at a voltage higher than that of the second network to perform a fast charge of the low battery. voltage.

In another embodiment of the method, when, at an insufficient current supplied by a DC / DC converter for supplying the second electrical network, a current supplied by the first energy storage device of the first electrical network is added, the when the switch is then in the closed position, when the engine is started by the alternator-starter, the switch is placed in the open position by the management means to prevent very large fluctuations in the voltage of the first network on the second electrical network. feeding the sensitive elements ..

The invention also relates to a management device of a power supply system for implementing the method of managing a hybrid vehicle that can operate according to different life situations, as described above, the hybrid vehicle, comprising: - a drivetrain power train having a heat engine coupled to the vehicle wheels via a clutch and a gearbox, an electric machine mechanically coupled through said gearbox to the wheels of the vehicle; vehicle, - a first electrical network connecting at least a first energy storage device, an alternator-starter that can be configured either as a starter for launching the heat engine, or as a current generator, the first auxiliary electrical elements of the vehicle not very sensitive to variations in electrical supply voltage, - a second energy storage device elec to supply at least the electrical machine; - a second electrical network connected to a continuous output of a DC / DC converter powered by the second electrical energy storage device; second auxiliary electrical elements of the vehicle responsive to voltage variations; electrical power supply connected to the second power grid, - a switch having two terminals, the switch being connected by one of these two terminals to the first power grid and the other terminal to the second power grid, the switch further comprising a control input to be put, either in the closed position to electrically connect the two networks, or in the open position to isolate the two networks, characterized in that it is configured to manage the position of the switch so that said switch is controlled in the open position for at least one time of the operating life situation of the v vehicle.

The invention is applicable to a hybrid vehicle comprising a management device according to the invention.

A main object of this invention is improved management of the switch connecting the two electrical networks of the vehicle. Another purpose is to control the switch, in the open position, according to different vehicle life situations, for the longest possible times.

The invention will be better understood by descriptions of management methods, according to the invention, of the coupling switch between two electrical networks of a hybrid vehicle with reference to the indexed figures in which FIG. 1, already described. , shows a state-of-the-art hybrid traction-chain vehicle equipped with a Stop and Start system - FIG. 2, already described, shows an electrical architecture of the parallel hybrid vehicle of FIG. 1 comprising a switch connecting two electrical networks of the vehicle; FIG. 3 shows a control flowchart according to the invention of a switch of the architecture of FIG. 2 during a start of the heat engine; FIG. 4 shows the torque characteristics Cp of an alternator starter of a vehicle; and FIG. 5 shows a control flowchart, according to the invention, of the switch of the architecture of FIG. 2 during a low voltage battery charge.

Subsequently will be described various control methods according to the invention, the switch Int connecting the two electrical networks R1, R2 30 of the architecture of Figure 2. UC management means 78 are provided to manage the open position or closed the Int switch by the control input Ec of the Int switch.

FIG. 3 shows a control flowchart, according to the invention, of the switch of the architecture of FIG. 2 during a start of the heat engine of the hybrid vehicle of FIG. 1. In a first life situation, the MTH heat engine is at a standstill 80. The DC / DC converter 60 is powered by the battery BT HT 62. before starting: In a first case (yes) (step 82), if the DC / DC converter 60 provides enough current to feed the second electrical network R2 and in particular the AUX SE sensitive electrical auxiliary elements, the switch Int is placed in the open position (step 84), - when starting the thermal engine MTH (step 86) the Stop and Start device is set to starter configuration to start the engine, the switch Int is controlled by the UC management means to remain in the open position (step 88) during startup and after starting the engine. In this first life situation, during the starting of the motor by the power supply of the starter 46 by the battery BT 40, the switch Int being open, the fluctuations of the voltage of the battery base voltage BT 40, due to the consumption significant current through the starter of the Stop and Start system, do not affect the sensitive elements AUX SE 70 of the vehicle.

In another extreme case (no) (step 82) in which, at an insufficient current supplied by the DC / DC converter 60 to feed the second electrical network R2, a current supplied by the battery BT 40 of the first network is added, With the switch Int in the closed position (step 90), the switch Int is placed in the open position (step 92) during the start of the heat engine MTH (step 94) by the management means UC 78 to avoid very strong fluctuations in the voltage of the first network R1 on the second electrical network R2 supplying the auxiliary electrical elements sensitive to the S.

When the MTH engine is started by the alterna-35 starter, the inrush currents are of the order of 6 to 800 amperes, which produces a large voltage drop across the LV low voltage battery 40. 12 volts for starting. In the case of a conventional vehicle of the state of the art, auxiliary electric AUX SE elements are so-called sensitive electrical consumers, such as headlights, dashboard etc. They are connected to the low voltage battery BT 40 and the voltage drop causes unpleasant flicker for the driver. Opening the switch Int to isolate these sensitive elements of the battery used for startup, avoids these disadvantages. These sensitive elements are powered by the DC / DC converter 60 connected to the 1 o second electrical network R2.

Another advantage of keeping the switch Int open is the improvement of the starting capacity of the alternator-starter. Indeed, the torque that the alternator-starter is capable of supply depends mainly on the temperature of the latter. The more the alternator-starter is hot, the more torque it is able to provide decreases. It is therefore necessary to limit the temperature rise of the latter. However, the first temperature rise factor of an alternator-starter comes from its operation as an alternator (current generator). By limiting the operation in alternator mode to a minimum, that is to say to the charge of the low voltage battery BT 40, the alternator-starter is obtained better availability of its torque. Figure 4 shows the torque characteristics Cp of an alternator starter of a vehicle as a function of the Rg revolutions per minute for different increasing temperatures t1, t2, t3 and t4 of operation.

FIG. 5 shows a control flowchart, according to the invention, of the switch Int of the architecture of FIG. 2 during a low voltage battery charge LV of 12 volts. In a second life situation, the engine is running (step 100). The switch Int is placed in the open position (step 102) by the management means UC: the two electrical networks R1, R2 are then isolated. The 12-volt LV low voltage battery 40 is charged by the generator-configured alternator (step 104) to a higher voltage U than the second 12-volt network R2 for accelerated charging (106). low voltage battery BT 40. The second electrical network R2 being isolated from the first by the opening of the switch Int, the sensitive elements AUX SE 70 are then exclusively powered at their nominal voltage 12 volts, voltage that is provided by the DC converter / DC of the second network R2 and therefore safe for them. The charging of the low voltage battery BT 40 is shorter the higher the charging voltage U applied to it.

Indeed, a vacuum voltage battery E and internal resistance r provides a current I in a load under a voltage U. In known manner, the relationship between the no-load voltage E and the load voltage U is given by: U = Er.l is l = (EU) / r For E and r constant when charging (I negative charging according to the convention of the current directions), a high load voltage U should be used to accelerate the charge of the battery. In a conventional vehicle, the charging voltage rarely exceeds 14.5 volts because the entire network (the two networks R1, R2 in the case of the structure of Figure 2) is connected to the low voltage battery BT 12 volts and higher voltage may damage sensitive electronic components. Putting the switch Int in open position thus makes it possible to overcome this limited voltage constraint guaranteeing, on the side of the second network R2 connected to the DC / DC converter 60, a voltage of less than 14.5 volts and, on the the first network connected to the alternator-starter configured as a generator, a higher charging voltage U allowing faster charging.

In the management of the switch Int of the network of FIG. 2, by the management means UC according to the invention, the switch Int is kept in the open position most often and for a long time possible in the different life situations. of the vehicle. This limits the number of operations of the switch and thus to ensure a mission profile of said switch much less severe, which results in better network management reliability. A possibility of closing the switch Int is kept in the unusual case of failure of one of the electrical sources (low voltage battery, BT HT battery or DC / DC converter) thus allowing increased availability of the vehicle or in the case where the supply of sensitive elements (vehicle on-board system) is more favorable with one or other of the energy sources.10

Claims (7)

REVENDICATIONS1. A method for managing an electric power system for a hybrid vehicle that can operate according to different life situations, the hybrid vehicle comprising: - a drivetrain power train comprising a heat engine (10) coupled to the wheels (20, 22) of the vehicle by means of a clutch (12) and a gearbox (14), an electric machine (30) mechanically coupled via said gearbox to the wheels of the vehicle, - a first network electrical device (R1) connecting at least: a first energy storage device (40), an alternator-starter (46) that can be configured either as a starter for starting the heat engine or as a current generator, first electric elements auxiliaries (44) of the vehicle which are insensitive to variations in electrical supply voltage; - a second electrical energy storage device (62) for supplying at least the electrical (30), - a second electrical network (R2) connected to a DC output of a DC / DC converter (60) fed by the second electrical energy storage device 20, second auxiliary electrical elements (70) of the vehicle responsive to variations in electrical supply voltage connected to the second electrical network, - a switch (Int) having two terminals (A and B), the switch being connected by one (A) of these two terminals to the first electrical network ( R1) 25 and the other terminal (B) to the second electrical network (R2), the switch further comprising a control input (Ec) to be put, either in closed position to electrically connect the two networks, or in open position for isolating the two networks; - management means (78) for managing the open or closed position of the switch (Int), characterized in that the management means (78) for managing the position of the switch (Int) are configured res so that it is controlled in the open position for at least one time of the operating life situation of the vehicle. 2. Management method according to claim 1, characterized in that the alternator-starter (46) being configured as a starter, it consists in putting the switch (Int) by the management means (78) in the open position when supplying the alternator-starter (46) for starting the heat engine (10), so as to avoid voltage variations, by overloading the second electrical network (R2), on the second auxiliary electrical elements (70) of the vehicle sensitive to variations in electrical supply voltages. 3. Management method according to claim 1, characterized in that, the heat engine (10) being in operation, it consists in putting the switch (Int) by the management means (78) in the open position to recharge the first energy storage device (40) only by the first electrical network (R1) of the vehicle, to limit the operation of the alternator-starter (46) in alternator mode. 4. Management method according to claim 3, characterized in that the two electrical networks (R1, R2) being isolated, the low voltage battery (40) is charged by the alternator-starter configured as a generator (104) under a voltage higher than that of the second network (R2) for accelerated charging (106) of the low voltage battery (40). 5. Management method according to claim 1, characterized in that, when an insufficient current supplied by converter (60) for supplying the second electrical network (R2) is added a current supplied by the first energy storage device ( 40) of the first electrical network (R1) the switch (Int) is then in the closed position (90), when starting the heat engine (92) by the alternator-starter (46) the switch (Int) is set in the open position (94) by the management means (78) to avoid very large fluctuations in the voltage of the first network (R1) on the second electrical network (R2) supplying the sensitive elements (70). 6. Device for managing a power supply system for implementing the method for managing a hybrid vehicle according to one of the preceding claims, the hybrid vehicle can operate according to different life situations having: - a chain of power train traction (GMP) comprising a heat engine (10) coupled to the vehicle wheels (20, 22) via a clutch (12) and a gearbox (14), an electric machine (30) mechanically coupled via said gearbox to the wheels of the vehicle; - a first electrical network (R1) connecting at least one first energy storage device (40), an alternator-starter (46) which can be 1 o Configured either as a starter for starting the heat engine or as a current generator, the first auxiliary electric elements (44) of the vehicle which are not very sensitive to variations in the electrical supply voltage, - a second electrical energy storage device (62) for supplying at least the electrical machine (30), - a second electrical network (R2) connected to a continuous output of a DC / DC converter (60) powered by the second electrical energy storage device (62), second auxiliary electrical auxiliary vehicle elements (70) to supply voltage variations connected to the second electrical network, - a switch (Int) having two terminals (A and B) ), the switch being connected by one (A) of these two terminals to the first power grid (R1) and the other terminal (B) to the second power grid (R2), the switch further comprising a control input (Ec) to be put either in the closed position to electrically connect the two networks, or in the open position to isolate the two networks, characterized in that it is configured to manage the position of the switch so that says it switch (Int) is controlled in the open position for at least one time of the operating life situation of the vehicle. 30 Hybrid vehicle comprising a management device according to claim 6.