EP0260176B1 - Control process for a reversible electric generator-motor machine of a motor vehicle, and use of such a process - Google Patents

Description

The invention relates to a method for controlling a reversible electric machine, that is to say a machine which can operate either as a generator (alternator), connected to a battery and to current consuming elements, or as a motor with a restart of a flywheel, intended for a motor vehicle, this machine comprising an armature and a wound inductor, the inductor being controlled, during operation as an alternator, by a regulator capable of regulating the voltage delivered by the armature to the vehicle's electrical network.

The engine operation of such an electric machine corresponds either to the use as a starter of this machine, or in the use as a revival motor of a flywheel, in particular, in the case where the vehicle is equipped an energy recovery system using such a flywheel.

It is known that currently on most motor vehicles, passenger cars or heavy goods vehicles, the electric generator, in particular the alternator, and the starter are constituted by two separate electric machines. In the interests of economy and efficiency, we are trying to make a single electric machine that can be used both as a generator (alternator), sometimes as a motor (starter or motor to restart a flywheel) and which ensures performance sufficient for both types of operation.

FR-A-2 512 406 relates to an on-board electrical installation for vehicles, in particular motor vehicles, comprising an alternator which can operate as a motor (starter) while being supplied with from a battery. The alternator in this installation is of the permanent magnet inductor type. It is therefore not possible to modify the excitation of the inductor, unlike the case of a wound inductor.

The requirement relating to sufficient performance is difficult to meet because the electrical service conditions are not the same depending on whether the machine operates as a generator or as a motor.

JP-A-59 185 872 describes a method for controlling a reversible electric machine which can operate either as a generator (alternator), connected to a battery and to current-consuming elements, or as a motor, intended for a motor vehicle, this machine comprising an armature and a wound inductor, the inductor being controlled, during operation as an alternator, by a regulator capable of regulating the voltage delivered by the armature to the electrical network of the vehicle.

There is no question, in this document, of the problem posed by the revival of a flywheel, when the electric machine operates as a motor.

The object of the invention is, above all, to provide a reversible electric machine, as defined above which, in particular, makes it possible to obtain satisfactory performance and efficiency both during generator operation and during engine operation, with relaunch. of a flywheel.

According to the invention, the method for controlling a reversible electric machine that can operate either as a generator (alternator>, connected to a battery and to current-consuming elements, or as a motor with restart of a flywheel, intended to a motor vehicle, this machine comprising a wound armature and an inductor, the inductor being controlled during alternator operation by a regulator capable of regulating the voltage delivered by the armature to the electrical network of the vehicle, is characterized in that, for engine operation, it is established from the voltage of battery, a regulated voltage higher than that of the battery, this regulated voltage being used at least for the supply of the armature and that the excitation of the inductor is controlled so as to cause an increase in the speed of rotation for which the torque of the machine operating as a motor is zero.

It is thus possible to restart the flywheel up to the relatively high speed for which the torque is canceled.

Advantageously, the inductor is also supplied by this regulated voltage.

Preferably, the excitation is controlled so as to obtain a maximum torque for each speed of rotation.

It is possible to control a proportionality coefficient k between the counter-electromotive force e and the speed of rotation ω so as to have at each instant k = U / 2ω, U representing the supply voltage of the armature.

Generally, the excitation is controlled from a determined speed ω 1 chosen in such a way that ω 1 = U / 2K1 where U is the supply voltage of the armature and K1 the coefficient connecting the counterelectromotive force to the speed of rotation.

Advantageously, during engine operation, the armature is piloted so as to limit the intensity of the current flowing in this armature to a predetermined value for rotational speeds ranging from zero speed to a limit value.

Preferably, the intensity of the armature current is maintained at a constant value over the entire speed range.

The invention also relates to the use of the method defined above for the control of an electric machine, the armature of which comprises several phases and the motor operation of which is ensured by electronic switching.

The invention consists, apart from the arrangements set out above, of a certain number of other arrangements which will be more explicitly discussed below in connection with particular embodiments described with reference to the attached drawings, but which are not in no way limiting.

FIG. 1 of these drawings is a characteristic current-speed curve of an alternator, the intensity of the current being plotted on the ordinate, and the speed of rotation of the alternator expressed in revolutions / minute, being plotted on the abscissa.

Figure 2 is a high speed characteristic of the electric machine operating as a motor nominal excitation and with stator phase supply (or induced) by electronic switching under nominal voltage, the torque being plotted on the ordinate, and the speed of rotation on the abscissa.

Figure 3 is an electrical diagram of a conventional control of a machine operating as an alternator.

Figure 4 is a diagram of a conventional control of the electric machine operating as a motor, with electronic switching.

Figure 5 is a plot of characteristics of an electric machine operating as a motor, under various conditions, some of which conform to the method of the invention.

Figure 6 is a plot of characteristics of an electric machine operating as a motor and whose excitation is controlled --------------------------- --- so as to push the speed corresponding to zero torque towards higher speeds.

FIG. 7 is a plot of characteristics deduced from that of FIG. 6 for a higher regulated armature voltage, according to the invention.

FIG. 8 is a plot of characteristics deduced from that of FIGS. 6 and 7 when the armature and the inductor are both supplied by the regulated voltage greater than that of the battery.

Figure 9 is a plot of characteristics of an electric machine operating as a motor ---------------------------------- ------- with control of the armature voltage so as to maintain the armature current at a constant value.

FIG. 10 is deduced from FIG. 9 for an armature voltage corresponding to the regulated voltage greater than that of the battery, according to the invention.

Figure 11 is deduced from Figures 9 and 10̸ while the armature voltage and the inductor voltage correspond to the regulated voltage higher than that of the battery.

FIG. 12 is a simplified electrical diagram of an installation for controlling an electrical machine according to the invention.

FIG. 13 is an electrical diagram of a variant of the control installation.

Figure 14, finally, is an electrical diagram of another alternative embodiment of the control installation.

Before starting the description proper, it should be specified that a reversible electric generator-engine machine for a motor vehicle, of the type of the invention, can be installed in two ways:

or else integrated into the engine flywheel and therefore rotating at the same speed as the crankshaft of the heat engine;

or else driven by the crankshaft by means of pulleys and belts and rotating at a speed greater than, and generally equal to approximately twice, that of the crankshaft.

To simplify the drafting, we will only consider the first layout where the rotational speeds of the heat engine and the electric machine are identical. The case of the second installation can be deduced from the previous one by a simple multiplying coefficient between the speed of the heat engine and that of the electric machine.

FIG. 1 of the drawings illustrates an example of characteristics of the intensity (range on the ordinate) of the current delivered by an alternator, integrated into the flywheel of the heat engine or driven by this engine with unit transmission ratio, at nominal excitation, as a function of the speed of rotation plotted on the abscissa and expressed in number of revolutions / minute. The priming speed Na of the alternator is close to 60̸0̸ revolutions / minute.

Figure 2 shows the characteristic torque (on the ordinate) and speed (on the abscissa) of the same electric machine as in the case of Figure 1, but operating this time in motor under nominal excitation and with stator phase supply by electronic switching under nominal voltage, as will be explained a little more in detail with reference to the diagrams of FIGS. 3 and 4.

The diagram in FIG. 3 corresponds to the operation of the electric machine as an alternator, with a conventional control. The machine comprises a wound inductor winding 1, or excitation winding, controlled by a regulator 2 which controls the excitation current, passing through the inductor 1, so that a desired voltage is delivered at the output of the bridge 3 of rectifier diodes connected to the armature 4 comprising three phases L1, L2, L3 connected in star.

The diode bridge 3 comprises, in a conventional manner, six diodes. Two diodes are associated with each phase of the armature 4 which forms the alternator stator. The anode of the diodes D1, D2, D3 is connected to the output end of each phase winding L1, L2, L3, while the cathode of these diodes is connected to the + terminal of a battery 5 as well as to a terminal of the electrical network S of current consuming elements of the vehicle.

The cathodes of diodes D4, D5, D6 are connected to the output end of phases L1, L2, L3 while the anodes are connected to ground, to which is also connected the pole - of battery 5 and the other network terminal S.

The regulator 2 schematically comprises a comparator circuit 6 which receives, on one input, the voltage at the output of the diode bridge 3 and, on another input, a reference voltage. The output signal of the comparator 6 is sent to an amplifier 7 which controls the intensity of the current flowing in the inductor 1. It does not appear necessary to further detail these conventional circuits.

FIG. 4 schematically represents the control of the electronic switching of the electric machine for its operation as a motor. Identical items or playing similar roles to elements already described with reference to FIG. 3 are designated by the same references without their description being repeated.

The regulator 2 has not been shown in FIG. 4 and the inductor constituted by the excitation winding 1 is supplied under the constant voltage U of the battery.

Electronic switching means 8 are connected in parallel to the diode bridge 3 to ensure a sequential supply of the phases L1, L2, L3 of the armature 4 or stator.

The electronic switching means 8 comprise static switches Q1 ... Q6 which may be constituted by transistors or thyristors, connected in parallel to the diodes D1 ... D6. The switches Q1 ... Q6 are controlled from an electronic assembly 9 which receives information on the angular position of the rotor, or inductor 1, by sensors of the angular position of the rotor H1, H2, H3, spaced on a circumference surrounding the rotor. These sensors H1, H2, H3 can be constituted by Hall Effect sensors, or optoelectronic sensors.

An example of the supply sequence of the phases L1, L2, L3 allowing the creation of a rotating electromagnetic field is as follows:

The operating characteristics of the electric machine as a motor depend on the characteristics of the alternator operation.

Thus, if we refer again to Figure 2, we can see that the maximum rotation speed of the engine which is 60̸0̸ revolutions / minute corresponds to the starting speed of the alternator operation, illustrated by Figure 1 , since at this speed the electromotive force (in motor operation) already reaches the nominal voltage and completely opposes the passage of the stator supply current (or induced).

If the nominal current, when operating as an alternator, is large enough, the electric machine may supply, during its operation as a motor, a starting torque Cd at a speed for example of 20̸0̸ revolutions / minute, sufficient in the case where the engine is used as a starter. By cons, it is possible that the electric machine while having satisfactory characteristics for the alternator operation, does not provide, during engine operation according to the diagram of Figure 4, a sufficient torque Cd.

In addition, when the electric machine is intended to be used, during its operation as a motor, to ensure the revival of a flywheel, it will have to reach a relatively high speed of rotation, for example 40̸0̸0̸ revolutions / minute, which is greater than the limit speed of 60̸0̸ revolutions / minute corresponding to zero torque, from the diagram in FIG. 2 which itself corresponds to motor operation according to the connection in FIG. 4.

The invention aims, in particular, to provide a solution to these problems, that is to say to make it possible to obtain an electric machine, sufficiently dimensioned to operate as a generator (alternator) on board a motor vehicle, satisfactory characteristics during operation as an electric motor, that is to say as a starter and as a restart motor for a flywheel.

For this, in accordance with the invention, during operation of the electric machine as a motor, the supply voltage of the armature 4 and / or the excitation (inductor 1) is controlled in order to obtain the desired torque characteristics. -speed.

Before discussing in more detail the control method of the invention and the means used for the implementation of this method, we will consider the operating equations of the electric machine as a motor.

où

ω

= vitesse de rotation en rd/s

N

= nombre de conducteurs de l'induit

2a

= nombre de voies d'enroulement du bobinage induit

2p

= nombre de pôles de l'inducteur

Φ

= flux utile par pôle en Webers

The fcem (counter-electromotive force) in volts of the machine working as a motor has the expression:

or

ω

= rotation speed in rd / s

NOT

= number of armature conductors

2a

= number of winding channels of the induced winding

2p

= number of poles of the inductor

Φ

= useful flow by pole in Webers

The electromagnetic torque C, in mN, for a current I in amperes in the armature supplied at the nominal voltage U, in volts, is:

In operation under nominal voltage U with a constant nominal excitation current i (therefore at k = K1 constant), the characteristic of electromagnetic torque C as a function of speed ω is the line in Figure 2. The limit speed is U / K1.

Equations (1) to (4) show that the torque C and the speed ω depend on the inductor currents, i.e. of the current flowing in the excitation winding 1, and induced, that is to say of the current flowing in the windings of the stator 4.

The control method according to the invention makes it possible to modify these torque and speed by acting on the currents by controlling the supply voltage of the armature and / or the excitation.

Current control can be carried out either from the nominal voltage U (battery voltage 5) or from a regulated voltage yU greater than that of the battery, and established from the voltage U by lifting means Of voltage.

When the nominal voltage U and a higher regulated voltage yU are thus available, three main main cases of operation can be envisaged.

^Case 1: the inductor 1 and the armature 4 are supplied by the nominal voltage U.

This corresponds to the assembly of FIG. 4 and to the conventional use of a reversible electric machine in its operation as a motor. The torque-speed characteristic is represented by the line C1 in FIG. 5.

Case ^2: the inductor 1 is supplied with the rated voltage U, while the armature 4 is supplied by the voltage yU. The torque-speed characteristic is then the line C2 in FIG. 5. With respect to the line C1, the gain in torque and speed is in the ratio y, since the voltage passes from the nominal value U to the value yU, while that the coefficient K1 remains equal to itself.

Case ^No. 3: the inductor 1 and the armature 4 are supplied at yU voltage.

The torque-speed characteristic is then represented by the line C3 in FIG. 5, the torque being multiplied by y², for the same speed of rotation, relative to the operation corresponding to the line C1. Indeed, the tension is multiplied by y, as well as the proportionality ratio which becomes yK1 instead of K1.

The speed corresponding to zero torque is the same as ^Case 1 and Case ^No. 3.

The lines C1, C2, C3 correspond to the lines i1, i2, i3 of the inductor current (winding 1) parallel to the abscissa axis (constant inductor current) and the lines I1, I2, I3 of the armature current ( winding 4), with a negative slope.

The torque-speed characteristics C2, and especially C3 (FIG. 5), make it possible to obtain a high torque at the relatively low speeds of rotation of the electric machine operating as a motor. These characteristics are suitable for starter operation, since the range of speeds obtained is sufficient.

Thus, by establishing in accordance with the invention, from the battery voltage U, a regulated voltage yU greater than that of the battery, and by using at least this voltage yU for the supply of the armature 4 (characteristic curve C2 in FIG. 5), and if necessary also for supplying the inductor 1 (straight line C3 in FIG. 5), the desired characteristics in torque-speed for the operation of the electric machine as a starter are obtained.

However, as already mentioned above, if the electric machine is used as a motor to restart a flywheel, the speed ranges are no longer sufficient.

For example, to reach a speed of 40̸0̸0̸ revolutions / minute, with a torque which will be equal to 25% of the starting torque, the speed limit at zero torque for the line C2 in Figure 5 should be 40̸0̸0̸ x (10̸0̸ / 75 ) = 5,333 rpm. If we consider that the zero torque limit speed for the line C1 is equal to 60̸0̸ revolutions / minute (as in the case of Figure 2), an amplification coefficient y of 8.88 will be necessary to obtain the characteristic C2 satisfactory . With such a coefficient y of 8.88, the current in the armature 4, which increases in the same proportions, becomes very high and the cost of electronics (electronic switching means 8) can become exorbitant.

The method of the invention provides, to avoid such a drawback, controlling the excitation of the inductor 1 so as to cause an increase in the speed of rotation for which the engine torque is canceled out. This increase is obtained by varying the supply voltage or the current of the inductor 1 so that the electromagnetic flux Φ varies and therefore the coefficient k connecting the counter-electromotive force to the speed of rotation [see equation (1 )].

Preferably, the excitation is controlled so as to obtain a maximum torque for each speed of rotation.

Theoretical explanations will first be provided to better understand the process of the invention. These theoretical explanations apply mainly to the basic case (case n ^o 1) ------------ which corresponds to the supply of the inductor and the armature from the nominal voltage U. then we can easily extrapolate to case ² and 3 referred to page 10.

We again consider equation (4) ---------------------- of the torque as a function of nominal voltage, speed and coefficient k. We calculate the derivative with respect to k of the couple C. We obtain:

This derivative shows that the torque C for each speed is maximum when k = U / 2ω. An optimal method for extending the speed zone, that is to say increasing the speed of rotation for which the motor torque is zero, consists in varying k according to a hyperbolic law as a function of ω. This variation of k, as already mentioned above, will be obtained by acting on the voltage or on the excitation current applied to the winding 1.

The variable k is physically limited to the value K1 for the lower rotational speeds going from zero speed ω = 0̸ to speed ω = ω1 such that:

For the speeds of rotation higher than ω1, one controls k, by acting essentially on the useful flow Φ by pole produced by the inductor, (see equation n ^o 1), to have at each moment:

The characteristics of torque C, armature current 1 (current in stator 4) and inductor current i (current in excitation winding 1) are plotted in Figure 6.

The curve 10̸ of the inductor current as a function of the speed of rotation, a curve which corresponds to the desired control of the excitation in order to obtain the desired torque-speed characteristic, comprises, first of all, a straight segment 11 parallel to the horizontal axis. This segment 11 corresponds to an intensity crossing the inductor 1 constant; this segment 11 corresponds to the constant value K1 of the proportionality coefficient k. From the speed ω = U / 2K1, the intensity of the inducing current decreases according to a hyperbolic law, represented by the arc of curve 12. The coefficient k decreases in a similar way.

The characteristic 13 of the torque C is composed of a rectilinear segment with a negative slope 14 from the zero speed to U / 2K1, for the speeds greater than this latter value, the curve 13 continues with an arc 15 of hyperbola, turning its concavity upwards. A non-zero value of the torque is thus maintained for speeds greater than U / K1.

The rectilinear segment in dashes 16 extending the segment 14 corresponds to the operating case illustrated in FIG. 2, in the absence of excitation control. It can be seen that for the speed U / K1 at which the torque is canceled in the case of operation without driving the excitation, the torque obtained is equal to K1U / 4R.

For a double speed 2U / K1, the torque obtained with the control of the excitation is equal to K1U / 8R.

Curve 17 illustrates the variation of the armature current I as a function of the speed of rotation.

This curve 17 comprises a first rectilinear segment 18 with a negative slope between the zero speed and the speed U / 2K1. Beyond this speed, the curve continues with a rectilinear segment 19 parallel to the abscissa axis, corresponding to a constant armature intensity.

The previously mentioned operating case corresponded to the supply of the armature and the inductor from the nominal voltage U.

If the armature 4 is supplied from a regulated voltage yU, while the inductor 1 remains supplied from the nominal voltage U, the operating characteristics of the motor are illustrated in FIG. 7 which is deduced from FIG. 6 by the introduction of the amplification coefficient y on the values involving the voltage U. These values have been plotted on the abscissa and ordinate axis, and it is not necessary to comment in more detail on this figure 7 on which we have designated by the same reference numerals as in FIG. 6, the various parts of the characteristics concerned.

In the case of operation where the armature 4 and the inductor 1 are supplied from the voltage yU, the characteristic curves of motor operation become those of FIG. 8 which are deduced from those of FIG. 6. The remarkable values have been plotted on the abscissa and on the ordinate and expressed as a function of y, U, R and K1. The different parts of the curves have been designated by the same reference numbers as in FIG. 6.

The extension of the torque-speed characteristic, by controlling k (driving the excitation), makes it possible to reduce the amplification coefficient y to obtain a desired speed of rotation. In the numerical example mentioned previously for a desired speed of rotation of 40̸0̸0̸ revolutions / minute one can reduce the coefficient y to 6.66, thanks to the piloting of k, instead of the value 8.88 expressed previously.

Advantageously, during the operation of the electric machine as a motor, the armature 4 is controlled so as to limit the intensity I of the current flowing in this armature to a predetermined value for rotational speeds ranging from zero speed to a limit value .

Usually, as shown in FIGS. 6, 7 and 8, a starting current is imposed, in the armature 4, rotor locked, equal to twice the minimum value of the armature current I.

The method of the invention, which has just been mentioned, makes it possible to limit the armature current to a single value, namely its minimum value, by controlling the supply voltage of the armature 4.

For the explanations which follow, we will consider the basic case where the inductor 1 and the armature 4 are supplied from the nominal voltage U, which corresponds to the characteristics of FIG. 6.

In this FIG. 6, the minimum value of the armature intensity I is equal to half of the locked rotor intensity, that is to say equal to: 1/2 x U / R.

As can be seen in this FIG. 6, in the speed zone corresponding to segment 18, the armature intensity is usually greater than this minimum value.

avec, en fait, k = K1.To maintain the armature current I at the minimum value U / 2R in the speed range from ω = 0̸ to the limit value ω1 = U / 2K1, we reduce, from the nominal value U, the voltage d of the armature 4 in a z ratio so that:

with, in fact, k = K1.

The coefficient z must therefore vary linearly from 1/2 for ω = 0̸ to 1 for ω1 = U / 2K1.

In practice, the armature 4 will be supplied with a voltage U / 2, half of the nominal value, at zero speed, and this voltage will be linearly increased as a function of ω1 until the nominal value U reached for ω1 = U / 2K1. Beyond this speed ω1, the armature 4 will remain supplied with this constant nominal voltage U.

This limitation of the armature current, in the range of speeds considered, causes a reduction in the torque C which will remain equal to the constant value:

The characteristics of FIG. 6 are modified as illustrated in FIG. 9.

The characteristic 17a of the armature current, in FIG. 9, consists of a rectilinear segment parallel to the axis of the abscissa. Thus, the inclined segment 18, with a negative slope, of Figure 6 is deleted.

For the range of speeds between zero speed and U / 2K1, the characteristic 13a of the torque has a segment 14a parallel to the abscissa axis and whose ordinate is equal to K1U / 2R. This ordinate is equal to half of the ordinate at the origin of the characteristic 13 of the torque in FIG. 6. Beyond the speed U / 2K1, the torque characteristic is constituted by a similar hyperbola arc 15a in arc 15 of figure 6.

Characteristic 12a of the intensity of the inductor current (current in winding 1) and the coefficient k is similar to characteristic 12 of FIG. 6.

The formulas (8) and (9) can be easily transposed to Case ^No. 2 and ^No. 3.

In case ^No. 2 corresponding to Figure 7, where the inductor 1 is supplied from the nominal voltage U controlled depending on the rotational speed, and the armature winding 4 is supplied at high voltage yU, the coefficient z may vary linearly according to the following formula:

The torque is given by the formula:

The characteristics plotted in FIG. 10̸ correspond to this second operating case.

Comme k est maintenu égal à K1, le couple est donné par :

In the case of operation ^No. 3, shown previously in Figure 8, in which the armature 4 and the inductor 1 are supplied from the high voltage yU, the z coefficient is obtained by equation (8) given previously to know:

As k is kept equal to K1, the torque is given by:

Figure 11 provides the characteristics corresponding to the operation according to this Case ^3.

FIGS. 12 to 14 illustrate exemplary embodiments of an installation for implementing the method of the invention.

The practical realization of the installations corresponding to the three cases of inductor and armature control mentioned above is carried out using conventional assemblies or sub-assemblies combined according to the method.

For inductor 1, the usual regulator 2 of the alternator can be used.

For the armature 4, an assembly of the switching power supply type may be perfectly suitable.

FIG. 12 is a block diagram of a reversible machine and of the associated control installation E making it possible to control the voltage of the inductor 1 supplied from the nominal voltage U, and to control the voltage d armature 4 supplied from the high voltage yU.

The elements of Figure 12 identical or playing roles similar to elements already described with respect to Figure 3 are designated by the same references, possibly followed by the letter a, their description may thus not be repeated.

The installation E comprises connection means J1 and J2 in the generator position (operation of the electric machine as an alternator) and in the engine position. These means J1 and J2 are constituted by two-position inverters A (alternator) and M (engine).

The inverter J1 in position A provides a connection between an input terminal of the regulator 2a and the output of the comparator 6a, suitable for comparing a reference voltage with the voltage U. The other inverter J2 whose displacement is coupled to J1 , is also in position A and ensures, in this position, the connection between the output of the diode bridge 3 and the + terminal of the battery.

The alternator operation of the electric machine for this position A of the connection means J1 and J2 is conventional. The regulator 2a acts on the excitation 1 so as to charge the battery at its nominal value, for example 14 volts or 28 volts, and to supply the current to the consumers S of the vehicle.

For its other position M, the inverter J1 connects the input terminal of the regulator 2a to a line receiving, from an output of the control electronics 9a, a signal representative U / 2ω produced by this electronics 9a. This signal corresponds to the control defined by equation (6).

The regulator 2a which receives on its input the signal representing U / 2ω will regulate the excitation current flowing in the winding 1 according to this law, which makes it possible to obtain the desired piloting of the inductor.

The electronic module 9a also controls, as explained with reference to FIG. 4, the supply of the phases L1, L2, L3.

The other inverter J2 in its position M ensures the connection of the output of the diode bridge 3 with the output of a regulated voltage source 20̸, this output being under the voltage zyU. The 20̸ source is a switching power supply type assembly. The coefficient zy is also developed by the electronic assembly 9a, one output of which is connected to the input of a comparator circuit 21. This circuit receives, on another input, the voltage supplied to the output of the source 20̸. The circuit 21 provides, on its output connected to an input of the source 20̸, a signal representing the difference between the voltage delivered by the source 20̸ and the reference voltage zyU which controls the source 20 so as to provide at its output, a voltage equal to zyU.

FIG. 13 schematically shows another possible embodiment of the control installation according to the invention, installation equivalent to that of FIG. 12, but based this time on a piloting of the armature 4 and of the inductor 1 at the level currents, while in the case of Figure 12 the control was carried out at the voltages.

The elements of FIG. 13 identical or playing roles similar to elements of the installation of FIG. 12 are designated by the same references possibly followed by the letter b. The assembly of FIG. 13 requires current sensors represented by the two resistors 22, 23 placed respectively in series with the inductor winding 1 and the induced winding 4.

The output of the control electronics 9b, on which a signal U / 2ωr is supplied, r being the value of the resistor 22, is connected to an input of a comparator 24 whose output is connected to the terminal M of l 'reverse gear J1. Another input of the comparator 24 receives the voltage signal created across the resistor 22 by the inductor current i. The comparator 21, the output of which is connected to an input of the regulated voltage source 20̸ receives, on an input, a signal, produced by the control electronics 9b, representing the constant value In which is equal to U / 2R in case ^No. 1, or yU / 2R to case ^No. 2.

The other input of the comparator 21 receives the voltage signal taken from the terminals of the resistor 23. More precisely, this input is connected to a terminal 25 of the resistor 23, the other terminal of which is connected to ground.

The operation of the installation of FIG. 13 is similar to that described for FIG. 12, the difference consisting essentially in the control of the excitation current i as a function of the speed ω and of the induced current I which is maintained at the value constant In.

The excitation or inductor current i is controlled by the regulator 2a in response to the output signal supplied by the comparator 24.

The control of the armature current I is ensured by the voltage source 20̸ which supplies a voltage zyU, in response to the output signal from the comparator 21, such that I remains equal to In.

The mounting type of Figure 13 makes it easy to achieve the piloting Case ^No. 3 operating ------------------- corresponding to the power of the inductor and armature from a voltage yU.

For this, as shown in Figure 14, a third inverter J3, similar to J1 and J2, is provided on the connecting conductor of the excitation winding 1 at the + terminal of the battery 5. This inverter J3 is connected so that in position A (alternator) the excitation winding 1 is supplied from the battery voltage U. This inverter J3 in position M supplies the excitation winding 1 with the voltage zyU supplied by the source 20̸.

The control electronics 9b generates a signal In = yU / 2R.

The same references have been used in this FIG. 14 as those used in FIG. 13 to designate the identical elements or playing similar roles.

The connection means J1, J2 and J3 of this figure 14 are connected so as to move together and to be simultaneously either in position A or in position M.

The functions to be performed by the control electronics could advantageously be provided by a microprocessor, which could take care of other useful functions such as current and voltage protection, thermal protection, fault diagnosis.

Claims (7)

1. A control procedure for a reversible electrical machine, of the kind that is capable of working either as a generator (alternator), connected to a battery and having two elements for consuming current, or as a motor with restarting by an inertia flywheel, for an automotive vehicle, the said machine comprising a wound armature and a wound choke, the choke being controlled, during operation as an alternator, by a regulator which is adapted to regulate the voltage delivered by the armature to the electrical system of the vehicle, characterised by the fact that, for operation as a motor, a controlled voltage (yU). greater than that of the battery, is established from the battery voltage (U), the said controlled voltage being used at least for the supply of the armature (4), and that the excitation of the choke (1) is controlled in such a way as to cause an increase to take place in the rotational velocity for which the torque of the machine operating as a motor is cancelled out.
2. A procedure according to Claim 1, characterised by the fact that the choke (1) is also supplied with the controlled voltage (yU).
3. A procedure according to Claim 1 or Claim 2, characterised by the fact that control of the excitation (1) is carried out in such a manner as to obtain a maximum torque for each rotational velocity.
4. A procedure according to Claim 3, characterised by the fact that a coefficient (k) of proportionality between the contra-electromotive force (e) and the rotational velocity (ω) is so controlled that at each instant of time, k = U/2ω, where U represents the supply voltage to the armature.
5. A procedure according to Claim 3 or Claim 4. characterised by the fact that the excitation (1) is controlled from a predetermined velocity (ω1).
6. A procedure according to any one of the preceding Claims, characterised by the fact that, during operation as a motor, the armature (4) is controlled in such a way as to limit the intensity (I) of the current flowing in the said armature to a predetermined value at rotational velocities going from zero velocity to a limiting value, the said intensity being preferably maintained at a constant value over the whole range of velocities.
7. The use of a procedure in accordance with any one of the preceding Claims, for the control of an electrical machine the armature (4) of which includes a plurality of phases (L1, L2, L3), and for which its operation as a motor is obtained by means of electronic commutation (8).

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