EP2315931A2

EP2315931A2 - Method and device for monitoring the start time of a heat engine of a vehicle

Info

Publication number: EP2315931A2
Application number: EP09784489A
Authority: EP
Inventors: Oussama Rouis
Original assignee: Valeo Equipements Electriques Moteur SAS
Current assignee: Valeo Equipements Electriques Moteur SAS
Priority date: 2008-07-24
Filing date: 2009-07-09
Publication date: 2011-05-04
Anticipated expiration: 2029-07-09
Also published as: JP5491503B2; FR2934331A1; CN102105675A; FR2934331B1; EP2315931B1; US8674633B2; JP2011528768A; WO2010010271A2; US20110227341A1; WO2010010271A3; CN102105675B

Abstract

The method is implemented in a vehicle in which the engine (2) is mechanically coupled with a polyphase rotating electrical machine having an inductor (3) that comprises position sensors (13) for a rotor (5). The method comprises carrying out a preflux by setting up an energizing current in the inductor (8) for a predetermined preflux time before setting up phase currents controlled by control signals (Sw1, Sw2, Sw3) phase-shifted by a variable phase shift angle (φ) dependent on a rotation speed (N) of the machine (2) relative to synchronization signals (Si1, Si2, Si3) produced by the sensors (13). During the start time, the phase shift angle (φ) is also dependent on an onboard power grid voltage (Vbat+X) between a first voltage (V1) and a second voltage (V2) that is greater than the first voltage (V1).

Description

Method and device for controlling the starting time of a thermal engine of a vehicle

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method and a device for controlling the starting time of a thermal engine of a vehicle.

The invention also relates to a micro-hybrid system comprising this device.

BACKGROUND ART OF THE INVENTION.

Considerations of saving energy and reducing pollution, especially in urban areas, lead motor vehicle manufacturers to equip their models with an automatic stop / start system, such as the system known as the Anglo -Saxon of "Stop and Go". As recalled by the company VALEO ELECTRICAL EQUIPMENT

ENGINE in the patent application FR2875549, the vehicles are made to operate in the mode "Stop and Go" with a reversible electric machine, or alternator-starter, coupled to the engine, powered by a UPS in "starter" mode. Using an alternator-starter in an operating mode

"Stop and Go" is, under certain conditions, to cause the complete shutdown of the engine when the vehicle itself is stopped, then to restart the engine after, for example, an action of the driver interpreted as a restart request. A typical "Stop and Go" situation is that of stopping at a red light. When the vehicle stops at the fire, the engine is automatically stopped, then, when the light turns green, the engine is restarted by means of the alternator-starter, as a result of the detection by the system of the depression of the engine. the clutch pedal by the driver, or any other action reflecting the driver's willingness to restart his vehicle.

It goes without saying that the automatic restart function performed by an alternator / starter system is a function that must be as transparent as possible for the driver of the vehicle. In alternator-starters consisting of a polyphase rotating electrical machine with inductor, the phase currents and the excitation current are generally provided simultaneously by the power circuits at the time of restarting. In US Pat. No. 6,335,609, it is found that, in these circumstances, the engine torque can be produced only with a perceptible delay.

This delay is due to the establishment of the magnetic flux in the rotor, and it is proposed to pre-flux the inductor before the establishment of the phase currents, so as to reduce the time required for the heat engine to reach a predetermined rotation speed.

However, the method is implemented by controlling the excitation current for a fixed period of time, and does not appear to be suitable for alternator-starters powered by an "14 + X" variable voltage edge electrical network, in which so-called "micro-hybrid" systems

There is therefore a need for a method and a device which makes it possible to maintain, within limits acceptable to the driver, the start-up time in the case of a micro-hybrid automatic stop / restart system architecture. where the voltage of the on-board electrical network depends on the state of charge of the ultra-capacitance.

GENERAL DESCRIPTION OF THE INVENTION

The present invention aims to meet this need and specifically relates to a method for controlling the starting time of a thermal engine of a vehicle, which is mechanically coupled to a polyphase rotating electrical machine with inductor.

This electric machine, known per se, comprises phase windings and sensors of the position of a rotor in number equal to the number of these phases, and is connected to an electrical network board. The method of interest is of the type of pre-fluxing by establishing an excitation current in the inductor for a predetermined pre-flux time prior to establishing phase currents.

These phase currents are controlled, also in a manner known per se, by control signals which are out of phase with a variable phase angle as a function of a speed of rotation of the machine. electric compared to synchronization signals produced by the sensors.

According to the invention, during the start-up time, the phase shift angle is also remarkably a function of a voltage of the on-board electrical network, in a range between first and second voltages, the second voltage being greater than the first.

In this way, in the method according to the invention, the starting time is independent of the voltage of the on-board electrical network.

Advantageously, the phase shift angle for a current value of the rotational speed is decreased when the voltage of the on-board electrical network increases between the first and second voltages.

Preferably, for each current value of the rotational speed of the electrical machine, the phase angle is constantly less than or equal to a maximum phase shift angle below which the start time is greater than a reference threshold when the voltage of the electrical network is equal to the first voltage.

According to another characteristic of the method according to the invention, the predetermined pre-fluxing time is a function of the voltage of the on-board electrical network. This predetermined pre-fluxing time is preferably decreased when the voltage of the on-board electrical network increases between the first voltage and the second voltage.

The invention also relates to a device for controlling the starting time of a thermal engine of a vehicle adapted to the implementation of the method described above.

In a manner known per se, this heat engine is mechanically coupled to a polyphase rotating electrical machine with inductor having phase windings and sensors of the position of a rotor in number equal to the number of phases. The electric machine is powered by power circuits connected to at least one onboard electrical network and controlled by a control circuit.

This control circuit comprises first phase current control means by control signals out of phase with a variable phase angle as a function of a speed of rotation of the machine. in relation to synchronization signals produced by the sensors, and further comprises second means for controlling a pre-flow.

The device according to the invention is remarkable in that it comprises first means for determining the phase shift angle during the starting time as a function of a voltage of the on-board electrical network.

Preferably, these first determining means are included in said first control means, and comprise a memory containing a tabulation of the phase shift angle as a function of the speed of rotation of the electric machine and the voltage of the on-board electrical network. .

The device according to the invention is also remarkable in that it further comprises second means for determining a pre-fluxing time as a function of a voltage of the on-board electrical network.

These second determination means are preferably included in the second control means, and advantageously comprise a memory containing a tabulation of the pre-fluxing time as a function of the voltage of the on-board electrical network for a reference threshold of the start-up time. of the engine.

The device for controlling the start-up time of a heat engine according to the invention preferably relates to a vehicle whose electrical network is connected to the terminals of at least one ultra-capacitor, or similar.

Remarkably, thanks to this device, the starting time is constantly about 450 ms when the voltage of the on-board electrical network varies between 18 V and 24 V.

The invention therefore also relates to a micro-hybrid system advantageously comprising the device for controlling the starting time of a heat engine described above.

These few essential specifications will have made obvious to the skilled person the advantages provided by the invention compared to the state of the prior art.

The detailed specifications of the invention are given in the following description in conjunction with the accompanying drawings. It should be noted that these drawings have no other purpose than to illustrate the text of the description and do not constitute in any way a limitation of the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic representation of an automatic stop / restart system micro-hybrid type using a start time control device according to the invention.

Figure 2 shows the start-up time of a heat engine in an automatic stop / restart system similar to that shown in Figure 2.

1, as a function of the voltage of the on-board electrical network, in the absence of the device according to the invention, FIG. 3 shows the variations of the starting time as a function of the pre-fluxing time and of a discrete set of levels of the voltage of the electrical network in an automatic stop / restart system similar to that shown in Figure 1, in the absence of the device according to the invention. The timing diagrams in FIG. 4 schematically show the phase shift angle between the synchronization signals produced by the sensors of the rotor position of a three-phase machine and the control signals of the phase currents.

Figure 5 shows the variations of this phase shift angle as a function of the rotational speed of the electrical machine for several values of the voltage of the on-board electrical network, so as to according to the invention, to maintain a constant starting time.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION The preferred embodiment of the invention relates to vehicles equipped with an alternator / starter with a micro-hybrid braking energy recovery device, as shown schematically in FIG.

Figure 1 shows an alternator-starter 1 coupled to a vehicle engine 2.

This alternator-starter 1 comprises a polyphase electrical machine with reversible excitation 3 coupled to the motor 2 by means of a transmission 4 by belt and pulleys. The electric machine 3 comprises a rotor 5 integral with an output pulley 6 at the end of the shaft 7. The rotor 5 has an inductor 8 supplied by means of a rotating commutator by an excitation circuit 9.

The machine 3 also comprises phase windings 10, or induced, powered by an inverter 11.

A control circuit 12 drives the power circuits of the machine 3, constituted by the inverter 11 and the excitation circuit 9, as a function of the information provided by a sensor of the position 13 of the rotor 5, and control signals. generated by an electronic control unit of the vehicle, the electronic control unit receives operating parameters of the engine 2, and other context information via dedicated wire links or a CAN-type data communication bus.

The inverter 11 is preferably constituted by a chopper circuit of the voltage of the on-board electrical network Vbat + X generating pulses, the frequency and the width of which are controlled by the control circuit 12, when the alternator-starter 1 operates in electric motor.

This same chopper circuit is a reversible AC - DC converter that operates as a synchronous rectifier when the alternator-starter 1 operates as an alternator. In the micro-hybrid type architecture shown in FIG. 1, the on-board electrical network is connected to the terminals of an ultra-capacitor 14 instead of being fed directly by an onboard battery 15, as in a conventional architecture. .

When operating as a generator, the electric machine 3 charges the ultra-capacitor 14 by means of the reversible reciprocating-continuous converter 11 operating as a rectifier and supplies the on-board electrical network with a voltage Vbat + X greater than the battery voltage Vbat.

Power conversion circuits 16 constituted by a DC-DC converter, allow exchanges of electrical energy between the on-board battery 15 and the ultra-capacitor 14.

According to a general principle of the invention, it is proposed, within the framework of a system performing the automatic restart functions, to keep the starting time of the heat engine 2 constant regardless of the voltage Vbat + X of the on-board electrical network. . Indeed, as shown in FIG. 2, in the absence of implementation of appropriate corrective measures, the start time Tdem of the heat engine 2 depends on the voltage Vbat + X of the on-board electrical network, that is, that is to say, the state of charge of the ultra-capacitance 14. The measurements 17 were carried out for a fixed pre-fluxing time

Tpref-max of about 150ms, corresponding to the magnetic saturation of the inductor 8, and a constant angle profile.

When the ultra-capacitor 14 is lightly charged, the start time Tdem, defined as the time interval between the instant when the electric machine 3 applies a torque to the heat engine 2 and the moment when it reaches reference speed of rotation can, under these conditions, reach unacceptable values, given the objective of transparency of the system sought.

It is therefore proposed a weighting function that adjusts the start parameters to ensure a mean start time Tdem for a range of nominal operating voltages.

In the case of an ultra-capacitor 14 of EDLC type (electrochemical capacitor with double layer), having a capacity of 1500 F and an operating voltage of 25V, it is considered that the nominal operating range V1, V2 is between 18V and 24V.

FIG. 3 shows the results of tests carried out on a microhybrid system similar to that shown in FIG. 1, without a device for controlling the start-up time, by varying the pre-fluxing time Tpref and for several levels of the voltage ( 18V, 20V, 22V, and 24V) of the Vbat + X on-board electrical network.

The pre-flow time Tpref varies between a minimum value Tpref-min, below which the start time is always greater than a reference threshold Tdem-ref, that is to say below which the start function is degraded, even at the maximum load of the ultra-capacitor 14, and a maximum value Tpref-max from which the magnetic saturation of the inductor 8 is observed.

The start time Tdem depends on the instantaneous engine torque supplied by the electric machine 3 during start-up, and this engine torque itself depends on the control of the machine 3 from the synchronization signals Si1, Si2, Si3 produced by the sensors of position 13 of the rotor 5. Figure 4 shows the synchronization signals Si1, Si2, Si3 from the sensors 13 of a three-phase machine 3 shown schematically in Figure 1.

These signals Si1, Si2, Si3 are binary signals having a duty cycle of 0.5 and which have between them the same nominal phase shift Φ, here equal to 120 °, the machine having three phases.

In a manner known in itself, the control of the electric machine 3 requires the reconstruction of control signals Sw1, Sw2, Sw3 of the chopper circuit 11 switching the phase currents having between them, in steady state, the same nominal phase shift Φ, but which have a phase shift angle φ with respect to the incoming signals Si1, Si2, Si3 variable as a function of the rotational speed N.

According to the method of the invention, the starting time of the heat engine 2 is made constant, regardless of the voltage Vbat + X of the electrical network on board between 18V and 24V, by controlling the instantaneous torque of the electric machine 3 during the entire duration of the start.

To do this, the phase shift angle φ is a function of both the speed of rotation N of the electric machine and the voltage of the on-board electrical network Vbat + X. Figure 5 shows four examples of variation curves of the phase shift angle φ as a function of the speed N parameterized by four values of the voltage of the electrical network Vbat + X (18V, 20V, 22V and 24V), the time of pre - Streaming Tpref being set at the maximum value Tpref-max of about 150ms.

The strategy of maintaining a constant startup time Tdem, regardless of the voltage of the on-board electrical network Vbat + X, consists in optimizing the control parameters of the electrical machine 3 for the on-board electrical network voltage Vbat + X the lowest V1, and degrade the performance of machine 3 for higher Vbat + X network voltages.

For the lowest network voltage V1, the pre-fluxing time Tpref is thus set at the maximum Tpref-max allowed by the magnetic saturation of the inductor 8, and the phase angle φ is maintained at a maximum value φmax in order to provide optimum torque during starting for each rotation speed N.

When the voltage of the on-board electrical network Vbat + X increases to its highest value V2, the performance of the electric machine 3 is degraded, if the pre-fluxing time Tpref remains constant, by decreasing the phase shift angle φ relative to the maximum phase shift angle φmax for each current value Ni of the rotation speed N, as shown in FIG. 5 For high on-board electrical system voltages, the performance of the electrical machine 3 is also degraded by decreasing the pre-fluxing time Tpref when the voltage of the on-board electrical network Vbat + X increases.

Figure 3 shows that if a reference threshold Tdem-ref is chosen as the start time Tdem to keep constant, it suffices to use a two-dimensional linear interpolation to calculate the pre-fluxing time Tpref corresponding to each value of the voltage of the on-board electrical network Vbat + X included in the nominal voltage range V1 to V2 with a phase angle profile φ current. The law of variation of the phase shift angle φ as a function of the rotation speed N and of the voltage of the network Vbat + X and, additionally, the law of variation of the pre-fluxing time Tpref as a function of the voltage of the network Vbat + X are tabulated in one or more memories of the control device 12 of the alternator-starter 1, which determines the driving angle profile of the electric machine 3, and the pre-flow time Tpref appropriate, depending the supply voltage Vbat + X applied to it.

It goes without saying that the invention is not limited to the single preferred embodiment described above.

Measurements and test results are given by way of example only for a 144/5 type starter-alternator (stator diameter: 144 mm, number of turns: 5) and an EDLC ultra-capacitance of 1500F / 25V.

The angle profiles shown in Figure 5 are suitable for this model when the pre-fluxing time Tpref is constant and set at about 150ms. Under these conditions, the electric machine 3 reaches about 2000 rpm in 450 ms, that is to say that the heat engine 2, which is coupled thereto by a gear ratio of about 2.5, reaches at the same time a reference rotation speed of approximately 800 rpm, whatever the voltage of the on-board electrical network Vbat + X in the range V1, V2 from 18V to 24V, The above description would apply to other models of alternator-starters 1, or other types of energy storage, for example a Ni-MH battery replacing the ultra-capacitor 14, retaining simply numeric values of parameters different from those indicated.

On the contrary, the invention embraces all the possible embodiments that would remain within the scope defined by the claims below.

Claims

1) A method for controlling the starting time (Tdem) of a heat engine (2) of a vehicle, said motor (2) being mechanically coupled to a polyphase rotating electrical machine with inductor (3) comprising phase windings ( 10) and sensors of the position (13) of a rotor (5) equal in number to the number of said phases, connected to an electrical network on board, and said method being of the type consisting in performing a pre-fluxing in establishing an excitation current in said inductor (8) for a predetermined pre-fluxing time (Tpref), prior to establishing phase currents controlled by control signals (Sw1, Sw2, Sw3) phase shifted by an angle of phase shift (φ) variable as a function of a rotation speed (N) of said machine (2) with respect to synchronization signals (Si1, Si2, Si3) produced by said sensors (13), characterized in that said angle of phase shift (φ) is moreover, during said time of starting (Tdem), a function of a voltage (Vbat + X) of said on-board electrical network, between a first voltage (V1) and a second voltage (V2) greater than the first voltage (V1).

2) A method for controlling the starting time (Tdem) of a heat engine (2) of a vehicle according to claim 1, characterized in that said starting time (Tdem) is independent of said voltage (Vbat + X) .

3) A method for controlling the starting time (Tdem) of a heat engine (2) of a vehicle according to any one of claims 1 or 2, characterized in that said phase angle (φ) for a current value (Ni) of said rotational speed (N) is decreased when said voltage (Vbat + X) increases between said first voltage (V1) and said second voltage (V2).

4) A method for controlling the starting time (Tdem) of a heat engine (2) of a vehicle according to any one of the preceding claims 1 to 3, characterized in that for each current value (Ni) of said speed of rotation (N), said phase shift angle (φ) is constantly less than or equal to a maximum phase shift angle (φmax) below which said start time (Tdem) is greater than a reference threshold (Tdem-ref) when said voltage (Vbat + X) is equal to said first voltage (V1). 5) A method for controlling the starting time (Tdem) of a heat engine (2) of a vehicle according to any one of claims 1 to 4, characterized in that said predetermined pre-fluxing time (Tpref) is a function of said voltage of said on-board electrical network (Vbat + X).

6) A method for controlling the starting time (Tdem) of a heat engine (2) of a vehicle according to claim 5, characterized in that said pre-fluxing time (Tpref) predetermined is decreased when said voltage (Vbat + X) increases between said first voltage (V1) and said second voltage (V2).

7) Device for controlling the starting time (Tdem) of a heat engine (2) of a vehicle adapted to the implementation of the method according to any one of the preceding claims 1 to 6, said engine (2) being mechanically coupled to a polyphase rotating electrical machine with inductor (3) having phase windings (10) and sensors (13) of the position of a rotor (5) equal in number to the number of said phases, said machine (3) being fed by power circuits (9, 11) connected at least to an on-board electrical network and controlled by a control circuit (12), said control circuit (12) comprising first phase current control means by control signals (Sw1, Sw2, Sw3) phase shifted by a variable phase angle (φ) as a function of a rotation speed (N) of said machine (3) with respect to synchronization signals (Si1, Si2 , Si3) produced by said sensors (13), and including in or second means for controlling a pre-fluxing, characterized in that it comprises first means for determining said phase shift angle (φ) during said start-up time (Tdem) as a function of a voltage of said electrical power supply network. edge (Vbat + X).

8) Device for controlling the starting time (Tdem) of a heat engine (2) of a vehicle according to claim 7, characterized in that said first determining means are included in said first control means, and comprise a memory containing a tabulation of said phase shift angle (φ) according to said rotational speed (N) and said voltage (Vbat + X). 9) Device for controlling the starting time (Tdem) of a heat engine (2) of a vehicle according to any one of claims 7 or 8 above, characterized in that it further comprises second determination means a predetermined pre-fluxing time (Tpref) as a function of a voltage of said on-board electrical network (Vbat + X).

10) Device for controlling the starting time (Tdem) of a heat engine (2) of a vehicle according to claim 9, characterized in that said second determining means are included in said second control means, and comprise a memory containing a tabulation of said pre-fluxing time (Tpref) predetermined according to said voltage (Vbat + X) for a reference threshold of said start time (Tdem-ref).

11) Device for controlling the starting time (Tdem) of a heat engine (2) of a vehicle according to any one of claims 7 to 10, characterized in that said on-board electrical network is connected to the terminals of at least one ultra-capacitance (14), or the like.

12) Device for controlling the starting time (Tdem) of a heat engine (2) of a vehicle according to any one of claims 7 to 8 above, characterized in that said start time (Tdem) is constantly d 450ms when said voltage (Vbat + X) varies between 18V (V1) and 24V (V2).

13) Micro-hybrid system, characterized in that it comprises the control device according to any one of claims 7 to 12 above.