WO2018024989A1

WO2018024989A1 - Electrical actuator for vehicle transmission system

Info

Publication number: WO2018024989A1
Application number: PCT/FR2017/052170
Authority: WO
Inventors: Pascal Maurel; Ibrahima SOGOBA
Original assignee: Valeo Embrayages
Priority date: 2016-08-05
Filing date: 2017-08-02
Publication date: 2018-02-08
Also published as: FR3054938A1; KR20190034580A; CN109690933A

Abstract

Actuator (2) for vehicle transmission system (3), comprising: - an electric machine (6) comprising a rotor and a stator, the machine (6) being such that the relationship between a quantity that is representative of the electromagnetic torque (T) exerted on the machine (6) and a quantity that is representative of the current (I) flowing through the electrical circuit of the stator involves a constant (K), (K) being the torque constant of the electric machine (6); - a static converter comprising a plurality of switching cells, the static converter being arranged so as to electrically link the electrical circuit of the stator to an electrical energy source; and - a system (32) for controlling the switching cells of the static converter, controlling these switching cells in a scalar manner and applying: a first control mode to the switching cells so that the torque constant (K) of the electric machine (6) takes a first value; and - a second control mode to the switching cells so that the torque constant (K) of the electric machine varies within a second range of values.

Description

Electric actuator for vehicle transmission system

The present invention relates to an electric actuator for a vehicle transmission system.

The invention applies particularly, but not exclusively, to the actuation of a single or double clutch whose idle state can be normally engaged or normally disengaged, the actuation of a gearbox synchronizer for manual transmission,

the actuation of a robotized gearbox, the actuation of a manual double-clutch gearbox, or the actuation of a coupling clutch of a heat engine with an electric machine when these two are part of a propulsion system of a hybrid vehicle.

Such a transmission system is supposed to have several configurations: a configuration in which it allows the transmission of a movement, that is to say that it is in the engaged state, and a configuration in which this transmission does not occur. does not perform, that is to say it is in the disengaged state. The electric actuator then allows, via an electric motor, the maintenance of the transmission system in at least one of these configurations and the transition from one to the other of these configurations.

The actuator maintains the transmission system in a configuration requires the exercise by the latter of a holding torque on the transmission system, and the exercise of this torque is related to the power supply of the engine of the transmission. actuator by a holding current. To reduce the size of the electrical power source dedicated to the power supply of the motor, it is important that this holding current is low. In addition, this holding current is likely to generate by Joule effect heating in the engine, the reduction of this current reduces the risk of premature wear of the actuator, or even destruction by fire of the latter. Since this holding current I can be linked by a constant K to the electromagnetic torque T exerted on the electric motor according to the relation T = K * I, this makes it necessary to size the motor so that the constant K has a high value.

The passage of the transmission system from one to the other of the above configurations must be carried out quickly in order to respond satisfactorily to a set point. To obtain such rapidity, the motor must allow to obtain high speeds, which requires a constant K of low value.

Obtaining an electric actuator to reduce the holding current while responding satisfactorily to the dynamic instructions and assumes the fulfillment of conflicting requirements.

For this purpose, it is known to associate a small electric motor with a gearbox mechanically variable to adapt the speed and current of the electric motor in according to the instructions, and with a wear-compensating system of the transmission system. It is also known to associate a small electric motor with a fixed gear ratio, with an elastic system occasionally providing the engine with the necessary effort, and with a wear compensating system of the transmission system.

Such solutions are complex to achieve and require the addition of specific parts including a wear-compensating system of the transmission system, being consequently expensive and cumbersome.

The patent application EP 2860 869 in the name of the Applicant discloses an electric actuator comprising a vector control system switching cells of a static converter, configured so that the torque constant of the electric machine can take at minus two distinct values according to the command applied to said cells.

The Atmel Corporation application note of 31/07/2013 describes the operation of a scalar control, implemented in a BLDC motor. This operation makes it possible to know the states of the rotors without the use of the sensors.

In his module "control and control of electric actuators", taught at the University of Lyon 1 G. Clerc explains the application of a scalar command to a synchronous machine, allowing 3 'autopil hostage.

The aim of the invention is to make it possible to benefit from an electric actuator for a transmission system which makes it possible to reconcile the aforementioned requirements while overcoming the drawbacks of known solutions.

The invention achieves this, in one of its aspects, with the aid of an actuator for a vehicle transmission system, comprising:

an electric machine comprising a rotor and a stator, the machine being such that the relation between a quantity representative of the electromagnetic torque (T) exerted on the machine and a quantity representative of the current (I) flowing in the electric circuit of the stator involves a constant (K), (K) being the torque constant of the electric machine,

a static converter comprising a plurality of switching cells, the static converter being arranged to electrically connect the electrical circuit of the stator to a source of electrical energy, and

a system for controlling the switching cells of the static converter, said system being configured to apply a first control mode to the switching cells so that the torque constant (K) of the electrical machine takes a first value, and to apply a second control mode to the switching cells so that that the torque constant (K) of the electric machine varies within a second range of values,

the control system of the switching cells being configured to implement a scalar control of the switching cells of the static converter, said scalar control allowing the internal angle (ψ) of the electrical machine defined between the rotor flow in the machine electrical and the flux generated by the stator rotating field, takes a first value when the first control mode is applied to said switching cells and said scalar control allowing the internal angle (ψ) to vary in a second range of values when the second control mode is applied to said switching cells. The variation within the second range of values of the torque constant and the internal angle may be a continuous variation or a discrete variation approximating a continuous variation.

For the purposes of the present application, the variation of the torque constant of the electric machine is continuous when it describes a path between the first value and that of the value of the second range of values which is furthest from the first value. . This continuous variation corresponds to a continuous defluxing of the electric machine. The torque constant can then vary monotonically from the first value when the second control mode is applied.

According to the above aspect of the invention, a torque constant value is associated with the first control mode while a plurality of torque constant values are associated with the second control mode.

The first value of the torque constant may form a terminal, for example the upper bound, of the second range of values.

The internal angle (ψ) of the machine can be substantially equal to 90 ° when the first control mode is applied, and the internal angle (ψ) of the machine can vary, especially strictly between 90 ° and 180 ° when the second command mode is applied.

The above relationship may be a linear or affine relationship between the electromagnetic torque T exerted on the machine and the current I flowing in the electric circuit of the armature. The relationship is expressed then:

T = K x I + T ₀ where T ₀ is zero, if any.

Alternatively, the above relationship may be a linear or affine relationship between the electromagnetic torque T exerted on the machine and a current F, image by one or more mathematical transforms, for example of Clarke and Park, of the current I flowing in the electrical circuit of the armature, for example in the case where the electric machine is a synchronous machine with smooth poles, as will be seen later.

The relationship is expressed then:

T = K x / '+ T ₀ ' where TO 'is zero, if any.

In a variant, the electrical machine may be a synchronous machine with salient poles, the relation being then expressing:

T ⁼ K _M x / + K _RELUC x I ² + TQ

As a further variant, the above relationship may be a square relationship between the electromagnetic torque T exerted on the machine and the current I flowing in the electric circuit of the armature, for example in the case where the electric machine is a synchro machine. -reluctante, as we will see later.

The relationship is expressed then:

T = K x I ² + T ₀ "WHERE TO" is zero, if any.

Each control mode applied by the control system may correspond to a mode of operation different from the actuator. The passage from one to the other of these modes of operation of the actuator is then obtained by modifying the control of the switching cells. In other words, unlike the solutions according to the prior art, the possibility for the actuator to have at least two different modes of operation does not require the use of a complex hardware architecture and the selective use of some of the elements of this architecture according to the desired operating mode for the actuator. One and the same hardware architecture which is modified when necessary control allows according to the invention to benefit from an actuator with at least two distinct modes of operation.

For example, the control system varies the torque constant in the second range of values according to at least one of the following parameters:

- speed of the electric machine,

- stator power supply current of the electric machine

- amplitude of the supply voltage of the electrical machine

- electrical resistance of each phase of the stator of the electric machine,

inductance of each phase of the electric machine,

- counter electromotive force of the electric machine, and / or

- resistance (s) electrical (s) upstream and / or downstream of the static converter.

The control system can apply the first control mode when the actuator is in a static operating mode and it can apply the second control mode when the actuator is in a dynamic operating mode. The second mode of The control can then increase the mechanical power provided by the electric machine.

Alternatively, the first control mode and the second control mode may be applied when the actuator is in a dynamic operating mode, the first control mode corresponding to a first dynamic configuration and the second mode to a second configuration in a dynamic mode. dynamic. The first configuration corresponds for example to a slow dynamic that requires low speeds and high response times while the second configuration corresponds to a fast dynamic that requires fast speeds and short response times. The application of the first control mode for such a slow dynamic can reduce the consumption of the electric machine of the actuator.

The first value of the torque constant K of the electric machine can be high, so as to reduce the value of the current supplying the electric machine, without affecting the value of the torque exerted by the actuator on the transmission system. . This high value is suitable for example to maintain the transmission system in state or to slowly move the actuator.

The actuator may comprise a gearbox, and the latter may have a fixed reduction ratio, chosen according to the maximum force imposed by the transmission system on the actuator, so as to reduce the electromagnetic torque to be applied to the rotor of the electric machine when the actuator holds the transmission system in a given state.

This fixed reduction ratio advantageously makes it possible to achieve the compromise between:

the largest possible reduction in the value of the electromagnetic torque corresponding to the maximum force imposed by the transmission system and mentioned above, and

- a race or a minimum number of revolutions to travel the race

actuating the actuator from its rest position to a position where it maintains the transmission system in the given state in the shortest possible time.

This fixed value for the reduction ratio makes it possible, for example, to reduce by 25% to 50% the value of the electromagnetic torque allowing said holding with respect to the value of electromagnetic torque to be supplied by the actuator with a reduction gear enabling the displacement of the actuator from its rest position to the holding position in an allotted time which is for example between 80 and 150 ms for a clutch, and between 30 and 60 ms for a synchronizer actuator.

With such a reducer, it is possible to further reduce the value of the current required when the actuator is in the static operating mode. Indeed, the torque value that the actuator must exert is reduced, for the same high value of the torque constant K, the value of the current supplying the electric machine is further reduced. Thus, the value of the current drawn from a source of electrical energy is lowered significantly. The high value of the torque constant K, associated with the value of the reducing ratio of the gearbox, can make it possible to take for the supply of the electric machine only a current lower than 1 A to the source of electrical energy, which is for example the battery of the on-board network of the vehicle.

The second range of values for the torque constant K of the electric machine can be formed by small values. These low values can correspond to an operating mode being a rapid movement of the actuator, for example to follow a setpoint variation. In this mode of operation of the actuator, the electric current supplying the electric machine is more important. This mode of operation can

correspond to a transient operation of the actuator.

When the fixed value of the reduction ratio is chosen as mentioned above, the reduction of 25% to 50% of the value of the holding torque that this fixed value of reduction ratio causes causes a reduction in the amount of travel to be made at motor to move the actuator from its rest position to the position in which it maintains the transmission system in the given state. In order not to lengthen the time required for movement according to this stroke of the actuator, an electric machine would have to be able to turn two to four times faster. Controlling the switching cells so that the torque constant takes the low values, allowing the motor to run two to four times faster than the high value, can solve this problem.

The control system can be configured to limit the current supplied to the electrical machine when it is started, so as to avoid excessive heating in the electric machine or demagnetization of permanent magnets that can be used in the electric machine.

This limitation of the current can be adjusted according to the thermal state of the electric machine and the magnetization characteristic of the permanent magnets, this thermal state being able to be determined from a measurement of temperature and / or from a temperature model as described in the document FR 2 951 033.

The static converter may comprise several, in particular three, arms mounted in parallel, each arm comprising two switching cells in series separated from each other by a midpoint, each midpoint allowing the electrical connection of the converter to the electrical circuit of the armature of the electric machine.

The electrical machine is for example a synchronous machine and the static converter can form a polyphase inverter, in particular three-phase. The synchronous machine may be a permanent magnet rotor machine or a wound rotor machine. The synchronous machine may be a machine with salient poles or smooth poles.

It may still be a brushless DC machine (designated "BLDC" in English). Such machines are more robust and can perform better than those of DC machines. In such a machine, the torque constant K depends on the internal angle ψ of the machine, which is already mentioned as the angle defined between the rotor flow in the machine and the flux generated by the stator rotating field. In this case again, the static converter may be a polyphase inverter, in particular three-phase.

The control system may comprise a table storing sets of control values for the switching cells of the static converter, each state of the rotor of the electrical machine having a set of associated control values, the control system also comprising a selector of set of control values according to the detected state for the rotor of the electric machine.

Each set of control values of the table can be calculated according to the variation of the internal angle ψ for a given speed of the rotor of the electric machine.

Each set of control values can, once selected, be scaled by applying a duty cycle for the magnitude of the phase-to-phase voltage of the stator of the electric machine, which duty cycle is determined on the basis of the voltage and / or current in the stator of the electric machine.

The duty cycles to be applied to the switching cells of the static converter can be obtained by centering the values resulting from the scaling by applying the duty cycle of the selected set of control values.

The rotor of the electrical machine can occupy successively several distinct states, the actuator comprising at least one sensor for discriminating among these states which is occupied by the rotor at a given instant.

The control system may be configured to apply an auxiliary control mode when it receives information relating to the existence of a failure. This auxiliary control mode can act on the switching cells of the static converter so that the switching cell of each arm connecting the midpoint and the positive DC input of the static converter is non-conducting, and that the cell of

switching of each arm connecting the midpoint and the negative continuous input of the static converter is passing. The electric machine is then disconnected from the source of electrical energy, being on the contrary looped on itself. This increases the safety of the actuator since the motor of the latter is braked if it is driven by the load, as happens in the case where the transmission system is a simple clutch with a coupled idle state, and which is in the uncoupled state when the failure occurs. An undesired brutal takeoff of the vehicle is thus avoided and / or minimized.

In the case, for example, where the fault concerns one of the switching cells connecting the midpoint of an arm to the positive DC input of the static converter, this switching cell being locked in the on mode, the auxiliary control can then:

controlling the other switching cells connecting the other midpoints to the positive DC input of the converter so that they are on, and

controlling the switching cells connecting the mid-points to the negative continuous input of the static converter so that they are non-conducting,

in order to achieve the braking function.

When the fault concerns a switching cell connecting a midpoint to the negative DC input of the static converter and this cell is blocked in the on mode, a symmetrical control of that just described can be applied.

When the fault concerns one of the switching cells and the latter is blocked in the off state, the auxiliary control mode may consist in controlling the switching cells connected to the DC input of the static converter to which the switching cell victim of the failure is not connected.

In a variant, and especially in the case where the transmission system is a double clutch whose idle state is the uncoupled state, the auxiliary control mode may consist in rendering all the switching cells of the static converter , in order to accelerate the passage of the transmission system in the uncoupled state.

In all the above, the failure may relate to the actuator, the transmission system, more generally to the powertrain of the vehicle, or even more generally to the vehicle.

In all of the above, when the electrical machine is rotating, the actuator may comprise a member for measuring the angular position of the rotor of the rotating electrical machine.

The invention is not limited to the examples of electrical machines mentioned above. According to another of its aspects, the subject of the invention is also an assembly comprising: an actuator as defined above, and

- A vehicle transmission system, said system comprising a member adapted to be moved by the actuator.

The actuator may include an actuating member configured to move said transmission system member The member adapted to be moved by the actuator may be a clutch diaphragm or a transmitter cylinder, for example.

The transmission system can be a dry clutch, a dual dry clutch and a transmission synchronizer.

According to another of its aspects, the subject of the invention is also a method of controlling an actuator as defined above, in which the control of the switching cells of the static converter allows the value of the constant of torque takes at least one high value and a plurality of low values.

The method comprises the step of varying the torque constant among the low values, this variation occurring especially from the high value.

The method may include the step of controlling the switching cells so that the torque constant takes the high value when the actuator maintains the transmission system in a given state.

This given state may be the coupled state or in the uncoupled state of the transmission system. Maintaining the transmission system in this state by the actuator is reflected for the actuator in that the position of the latter setting no longer evolves and in that its movement is completed.

When the transmission system is a single or dual clutch whose idle state is the coupled state, the switching cells can be controlled so that the torque constant takes the high value for the actuator to maintain the transmission system in the uncoupled state.

When the transmission system is a single or dual clutch whose idle state is the uncoupled state, the switching cells can be controlled so that the torque constant takes the high value for the actuator to maintain the transmission system in the coupled state.

The method may include the step of controlling the switch cells such that the torque constant takes the low values to move the actuator. This step can be performed upon receipt of a displacement instruction and can make it possible to modify the state of the transmission system. The torque constant can then vary when it takes low values.

As previously mentioned, the control system can be configured so that the torque constant can take a single high value and a plurality of low values. The transmission system can be a clutch, and the switching cells can be controlled so that the torque constant takes a low value to bring the transmission system into the uncoupled state and the switching cells. can be controlled in such a way that the torque constant takes another low value to bring the transmission system into the coupled state.

In the case where the transmission system is a single clutch whose idle state is the coupled state, the larger low value of the torque constant can be used to bring the clutch into the coupled state, while the smaller small value of the torque constant can be used to bring the clutch into the uncoupled state.

In the case where the transmission system is a double clutch, the larger low value of the torque constant can be used to bring the clutch into the uncoupled state, while the smaller low value of the torque constant can be used to bring the clutch into the coupled state.

According to the above method, the control system may be configured to apply an auxiliary control mode to the switching cells when the control system receives information relating to the existence of a failure.

The transmission system is for example a single or double clutch, whose idle state is the coupled state, the auxiliary control mode can act on the transmission cells.

switching of the static converter so that:

the switching cell of each arm connecting the mid-point and the positive continuous input, respectively negative, of the static converter is non-conducting, and

- The switching cell of each arm connecting the midpoint and negative continuous input respectively positive static converter is passing, so as to brake the electric machine when it is driven by the load of the transmission system.

In a variant, the transmission system is a single or double clutch, whose rest state is the uncoupled state, and the auxiliary control acts on the switching cells of the static converter so as to make all of said cells non-passing. of

switching of the static converter, so as not to brake the electric machine when it is driven by the load of the transmission system.

In all of the above, the second range of values comprises at least two distinct values, so that the torque constant takes:

a first value when the control system applies the first control mode, and

- varies by taking at least two, including at least three, distinct values when the control system applies the second control mode.

The invention will be better understood on reading the following description of a nonlimiting example of implementation thereof and on examining the appended drawing in which: FIG. 1 is a kinematic representation of an assembly comprising an actuator according to an exemplary implementation of the invention and the transmission system with which it interacts,

FIG. 2 is an elevational view of the assembly of FIG. 1,

FIG. 3 is a diagrammatic representation of the switching converter control system of the static converter for electrically supplying the actuator electric motor, and

- Figure 4 is a graph showing the evolution as a function of the speed of the electric motor of different parameters.

FIG. 1 shows an assembly 1 comprising an actuator 2 interacting with a transmission system 3. In the example of FIG. 1, the transmission system 3 is a simple clutch.

In this example, the actuator 2 comprises a casing 4 cooperating with the casing of an electric machine 6. The casing can be fixed to the powertrain or the chassis of a vehicle.

The housing 4 can receive a reducer 7 driven in rotation by the output shaft 8 of the electric machine 6, and a roto-linear motion transformation system 9. The gear 7 here has a fixed transmission ratio. The reducer 7 may comprise one or two reduction stages. The value of the transmission ratio of the gearbox is in the example considered determined according to the maximum force imposed by the transmission system 3 on the actuator 2, so as to reduce the electromagnetic torque to be applied to the rotor of the electric machine 6 when it keeps the transmission system 3 in a given state.

The housing 4 also contains in the example considered an electronic card 10 for controlling the operation of the electric machine 6 so that the actuator 2 can have at least two distinct modes of operation. As will be seen later, this command consists in modifying the torque constant of the electric machine 6 so that it can take a first value and a plurality of values belonging to a second range of values.

A connector 11 is also carried by the housing 4, and it allows the electrical connection of the electronic card 10 to a source of electrical energy which is for example the battery of the vehicle onboard network. The connector 11 may also allow the electronic card 10 to be connected to the vehicle's CAN (Controller Area Network) bus. Thus the control of the electric machine 6 is allowed from the engine control unit (ECU) of the vehicle, the latter including implementing a supervision software of the transmission system 3.

The housing can also receive a position sensor 12 of a movable actuator element 2, for example a rotor position sensor of the electric machine 6. This sensor 12 may or may not The processing part of this sensor is for example carried by the card 10 while the measuring part of this sensor 12 is disposed at the level of the rotor of the electric machine 6.

The roto-linear motion transformation system 9 is for example a ball screw, a nut screw or a planetary bearing screw. The system 9 can thus be as described in the application filed by the Applicant on October 2, 2013 in France under the number 13 59544 whose contents are incorporated in the present application by reference. The system 9 allows, from the rotary motion transmitted by the gearbox 7, to move in translation a piston 13 of a transmitter cylinder 14 for changing the state of the clutch 3.

The displacement of this piston 13 on a first stroke, called dead travel, exposes an orifice 15 which connects the chamber 16 of the emitter cylinder 14 to a low pressure hydraulic reservoir 17. The displacement of the piston 13 on a second race, called race active, allows to cover this orifice, so that the fluid contained in the chamber 16 of the emitter cylinder 14 can be moved by the piston 13 to a receiving cylinder 18, via a hydraulic pipe 19. The receiving cylinder 18 of the example comprises an annular piston 20 coaxial with the axis of rotation X of the clutch 3. This annular piston 20 is in this example connected to a ball bearing 21 which moves in translation along the axis X the diaphragm of the clutch 3, for example via a fork.

Although not shown in the figures, the actuator 1 further comprises a static converter comprising a plurality of switching cells, the static converter being arranged to electrically connect the electrical circuit of the stator of the electric machine 6 to the source of aforementioned electrical energy. The static converter forms in the example described a three-phase inverter, comprising three arms connected in parallel, each arm comprising two series switching cells separated from each other by a midpoint, each midpoint allowing the electrical connection of the converter to the electrical circuit of the armature of the electric machine.

The electric machine is in the example that will be described a brushless DC motor (BLDC).

An exemplary embodiment of a control system 32 of the switching cells of the inverter will now be described with reference to FIG. This control system 32 allows:

to apply a first control mode in which the internal angle ψ takes a first value. This first value of ψ is for example equal to 90 °.

- Applying a second control mode in which the internal angle ψ takes several different values, these values being for example strictly between 90 ° and 180 °, for example between 90 ° and 170 °. This control system 32 comprises four modules 40, 41, 42 and 43 which will now be described.

The module 40 aims to generate a duty cycle for the amplitude of the phase-to-phase voltage of the stator of the electric motor, so as to control the position of the actuator 2. The module 40 receives as input a pre-filter 44 a signal representative of the position of the measured actuator. The output of this pre-filter attacks on the one hand the input of a speed saturation limit determination block 45 and on the other the input of an adder 46 which also receives as input the output of a block 50 of scaling. The input of block 50 comes from module 41.

The output of the summator 46 then attacks a proportional-integral corrector 53 whose output drives a speed saturation block 56 whose limits come from the block 45.

The pre-filter 44, the block 45, the block 50, the corrector 53 and the block 56 form here a position loop.

The output of the block 56 drives a summator 60 also receiving as input the signal coming from an observer 62 receiving as input an output signal of the block 50. An output of the observer 62 drives a block 64 for calculating sets of values of control for the switching cells of the inverter, this set of control values thus generating a waveform for the phase-to-phase voltage of the electric motor 6 of the actuator. In the example described, the inverter being three-phase, each set of control values contains values for the phase U, values for the phase V and values for the phase W of the three-phase voltage supplying the electrical machine 6. The output of this block 64 attacks the module 43, as will be seen later.

The output of the summator 60 attacks another proportional-integral corrector 66, the output of which drives a saturation block 67, the output of this block 67 driving a scaling block 69. The observer 62, the blocks 66, 67 and 69 form a speed loop.

The output of the block 69 drives an adder 70 which also receives as input a signal coming from a shaping block 74 receiving at the input, on the one hand, a signal representing the standard of the current of the measured inverter and the other a trigger signal to measure this standard of the inverter current.

The output of the summator 70 drives a proportional-integral controller 80 whose output drives a block 81 of saturation. The output of the saturation block 81 drives a scaling block 82 which also receives as input a signal representative of the voltage

power supply of the measured inverter, for voltage normalization purposes.

The output of this block 82 corresponds to the duty cycle of the amplitude of the voltage between phases of the stator of the electric motor, and forms an input of the module 43.

The module 41 makes it possible to determine the state of the rotor of the electric machine 6. This module 41 receives as input the signals supplied by Hall effect sensors, here three sensors arranged at 120 ° from each other, and compare the data provided by these signals to a table 85, each row of this table associating a combination of the values of the three Hall effect sensors to a state of the rotor of the electric machine 6.

Depending on the signals received, the state of the rotor of the electric machine can be incremented according to the arrow 86 or decremented according to the arrow 87.

The module 42 also receives as input the signals supplied by the Hall effect sensors, and this module 42 performs a detection of rising edges and falling edges. This module 42 also makes it possible to periodically interrupt the control of the switching cells of the inverter, to take into account the cases in which there is no rotation of the electric motor. The period T _s of this interruption varies for example between ΙΟΟμβ and 150μ8.

The output of the module 42 makes it possible to apply two different strategies for controlling the inverter, if necessary. The detection of an edge by the module 42 or the detection of the period T _s then causes the application by the module 43 of a new set of duty cycle values for the switching cells of the inverter.

The module 43 contains a table 90 containing the sets of control values calculated by the block 64, as mentioned above. These sets of values are calculated according to the value of the internal angle ψ of the electric motor 6 and the speed of this electric motor. These sets of values control the waveform of the voltage between the phases of the stator of the electric motor 6. In the example described, six sets of values are present and each set contains values for the phase U of the stator of the electric motor. values for the phase V of the stator of the electric motor, and values for the phase W of the stator of the electric motor. Also in the example described, the six sets of values do not correspond to 18 distinct values, with only seven distinct values being used.

The table 90 makes it possible to associate with each state of the rotor of the electric motor 6 a configuration of the switching cells associated respectively with the phases U, V and W of the voltage of the stator of the electric motor.

An example of these configurations is shown below

In this table :

0 corresponds to a situation of Z corresponds to the case where the two switching cells associated with the phase in question are both non-conducting,

H corresponds to the case where the switching cell associated with the phase in question and connected to the positive continuous potential is on,

- L corresponds to the case where the switching cell associated with the phase in question and connected to the negative DC potential is conducting.

The module 43 also contains a selector 95 allowing, when a state value is transmitted from the module 41, to choose another set of control values than the one previously applied. Thus, the set of control values on the basis of which is generated a set of duty cycle values is updated according to the rotation of the rotor of the electric motor, this set of values being itself calculated according to the value of the internal angle ψ of the electric motor and the speed of this electric motor 6.

The set of control values present at the output of the selector 95 is then scaled by a block 97 by taking into account the output of the block 82. The output of the block 82, which corresponds as already mentioned to the report setpoint cyclic of the amplitude of the voltage between phases of the stator of the electric motor, makes it possible to adjust the amplitude of the waveform to drive the electric motor 6.

The signal at the output of this block 82 drives the input of a summer 100 also receiving as input the output of a centering block 102. The output of the adder 100 contains the set of duty cycle values to be applied to the switching cells. of the inverter.

At the output of the module 43, for example, sets of duty cycle values are applied to the switching cells associated respectively with the phases U, V and W so that the latter take the following configurations:

Status HS U LS U HS V LS V HS W LS W

rotor

0 OFF OFF OFF OFF OFF OFF

1 OFF OFF V + V- OFF ON

2 U + U- OFF OFF OFF ON

3 U + U- OFF ON OFF OFF

4 OFF OFF OFF ON W + W-

5 OFF ON OFF OFF W + W-

6 OFF ON V + V- OFF OFF FIG. 4 represents, firstly, along a curve 150, the torque supplied by the electric motor 6 as a function of its speed, and according to a curve 160 the internal angle ψ as a function of the speed of the machine when the second control mode Synchronous motor is applied.

It can be seen in curve 160 that the control system 32 which has just been described makes it possible, from the value of the angle θ corresponding to the first control mode and here equal to 90 °, to make a variation in successive stages of this angle ψ during defluxing according to the second command mode. The variation of the angle ψ here approximates a continuous variation. In this FIG. 4, the curve 170 corresponds to the variation of the internal angle ψ as a function of the speed of the machine during vector control defluxing.

The invention is not limited to the example which has just been described.

Claims

claims

An actuator (2) for a vehicle transmission system (3), comprising:

an electric machine (6) comprising a rotor and a stator, the machine (6) being such that the relation between a quantity representative of the electromagnetic torque (T) exerted on the machine (6) and a quantity representative of the current (I) circulating in the electrical circuit of the stator involves a constant (K), (K) being the torque constant of the electric machine (6),

a control system (32) of the switching cells of the static converter, said system being configured to apply a first control mode to the switching cells so that the torque constant (K) of the electric machine (6) take a first value, and to apply a second control mode to the switching cells so that the torque constant (K) of the electric machine varies within a second range of values,

the control system (32) of the switching cells being configured to implement a scalar control of the switching cells of the static converter, said scalar control allowing the internal angle (ψ) defined between the rotor flux in the electrical machine ( 6) and the flux generated by the stator rotating field takes a first value when the first control mode is applied to said switching cells and said scalar control allowing the internal angle (ψ) to vary in a second range of values when the second control mode is applied to said switching cells.

An actuator according to claim 1, the control system (32) comprising a table (90) storing sets of control values for the switching cells of the static converter, each state of the rotor of the electric machine (6) having a associated control value set, the control system (32) also comprising a control value set selector (95) as a function of the detected state for the rotor of the electric machine (6).

3. Actuator according to claim 2, each set of control values of the table (90) being calculated according to the variation of the internal angle (ψ) for a given speed of the rotor of the electric machine (6).

Actuator according to Claim 2 or 3, each set of control values being, once selected, scaled by applying a duty cycle for the amplitude of the phase-to-phase voltage of the stator of the electric machine ( 6), this duty cycle being determined on the basis of the voltage and / or the current in the stator of the electric machine (6).

5. An actuator according to claim 4, the duty cycle to be applied to the switching cells of the static converter being obtained by centering the values resulting from the scaling by applying the duty cycle of the set of control values selected.

6. Actuator according to any one of claims 2 to 5, the rotor of the electric machine occupying successively several distinct states, actuator comprising at least one sensor for discriminating among these states which is occupied by the rotor at a given instant.

An actuator according to any one of the preceding claims, the control system (32) applying the first control mode when the actuator is in a static operating mode and the control system (32) applying the second control mode. when the actuation is in a dynamic operating mode.

8. Actuator according to any one of claims 1 to 7, comprising a gear (7) having a fixed reduction ratio.

9. An actuator according to any one of the preceding claims, the electric machine (6) being a brushless DC machine and the static converter forming a three-phase inverter.

10. An actuator according to claim 9, the internal angle (ψ) of the machine being substantially equal to 90 ° when the first control mode is applied and the internal angle (ψ) of the machine varying between 90 ° and 180 ° when the second command mode is applied.

11. Together, comprising:

an actuator (2) according to any one of the preceding claims, and

- A vehicle transmission system (3), said system (3) comprising a member adapted to be moved by the actuator (2).