Method for controlling a wound-rotor synchronous electric motor

Abstract

The invention relates to a method for controlling a synchronous electric motor (3) for a motor vehicle (1), carried out by an electronic control device (4), the electric motor comprising a stator (6) and a wound rotor (7) cooperating with the stator, the stator and the rotor each being powered by an electric current supplied by the electronic control device, the method comprising: - a first operating phase (P1) in accordance with a first control law; - reception by the electronic control device of at least one item of information relating to a temperature (Ts, Tr); - verification of at least one condition (C11, C12) dependent on the at least one item of information relating to a temperature; and subsequently, if the at least one condition is verified, - a second operating phase (P2) in accordance with a second control law..

Description

Description Title of the invention: Method for controlling a wound rotor synchronous electric motor Technical field of the invention

[0001] The invention relates to a method for controlling, by an electronic control device, a wound-rotor synchronous electric motor for a motor vehicle. The invention also relates to a powertrain for a motor vehicle comprising a wound-rotor synchronous electric motor, and an electronic control device configured to supply the stator and the rotor with an electric current. The invention finally relates to a motor vehicle comprising such a powertrain. State of the prior art

[0002] Electric or hybrid vehicles include an electric motor configured to drive the vehicle's drive wheels. Various types of electric motors are known for automotive vehicles, including synchronous electric motors. Among the commonly used synchronous electric motors, the main known electric motors are those with a permanent magnet rotor. These electric motors have the advantage of being simple to manufacture and particularly responsive.

[0003] Electric motors comprising a wound rotor are also known. The magnetic field generated by a wound rotor is obtained not by permanent magnets but by windings of electric wires carrying an electric current. This type of electric motor has the advantage of having very good efficiency at high speed and of not requiring rare earths for its manufacture. The rotor of such electric motors must be powered by an electric current, which is generally achieved by means of a power supply device comprising rings and brushes rubbing on these rings. The stator of such electric motors is also powered by an electric current.

[0004] A calibration phase of the electric motor makes it possible to define a control law for the electrical supply of the stator and the rotor according to a torque setpoint expressed by the driver of the vehicle. This control law is determined so as to achieve the best possible efficiency for the electric motor. In a normal operating mode of the electric motor, an electronic control device therefore provides a supply current to the stator and a supply current to the rotor according to said control law, to satisfy the torque setpoint.

[0005] Due to the high electrical currents used to power the stator and the rotor, the temperature of the electric motor can sometimes reach excessively high values, which could damage the electric motor. To protect the electric motor, the torque setpoint is then limited to a maximum value, strictly lower than the theoretical maximum torque that the electric motor could provide in normal operation. The electric motor then operates in a degraded mode and the vehicle user experiences an unwanted loss of power. Presentation of the invention

[0006] The aim of the invention is to provide a method for controlling a wound rotor electric motor which overcomes the above drawbacks and improves the control methods known from the prior art.

[0007] More specifically, a first object of the invention is a method for controlling a wound rotor electric motor making it possible to extend the operating mode without reducing the performance of an electric motor in the event of a high temperature of this electric motor. Summary of the invention

[0008] The invention relates to a method for controlling a synchronous electric motor for a motor vehicle, by an electronic control device, the electric motor comprising a stator and a wound rotor cooperating with the stator, the stator and the rotor each being powered by an electric current supplied by the electronic control device, the control method comprising: - a first phase of operation of the electric motor during which the stator and the rotor are each powered by an electric current supplied by the electronic control device according to a first control law configured to satisfy a torque setpoint, then - reception by the electronic control device of at least one item of information relating to a temperature, then - a verification of at least one condition dependent on at least one piece of information relating to a temperature, then if the at least one condition is verified, - a second phase of operation of the electric motor during which the stator and the rotor are each powered by an electric current supplied by the electronic control device according to a second control law configured to satisfy a torque setpoint, the second control law being different from the first control law, an electric current supplying the rotor being different during the second phase of operation compared to the first phase of operation for an identical torque supplied by the electric motor and / or an electric current supplying the stator ... torque provided by the identical electric motor.

[0009] The at least one piece of information relating to a temperature may comprise information relating to a temperature of the rotor, and the at least one condition may comprise the comparison of the temperature of the rotor with a first predefined temperature threshold, then if the temperature of the rotor is greater than or equal to the first temperature threshold, a second operating phase during which the electric current supplying the rotor is lower than during the first operating phase for an identical torque supplied by the electric motor.

[0010] The at least one piece of information relating to a temperature may further comprise information relating to a temperature of the stator, and at least one condition may further comprise the comparison of the temperature of the rotor with the temperature of the stator, then if the temperature of the rotor is greater than or equal to the temperature of the stator plus a first predefined offset, said second phase of operation during which the electric current supplying the rotor is lower than during the first phase of operation for an identical torque supplied by the electric motor.

[0011] The at least one piece of information relating to a temperature may comprise information relating to a temperature of the stator, and the at least one condition may comprise the comparison of the temperature of the stator with a second predefined temperature threshold, then if the temperature of the stator is greater than or equal to the second temperature threshold, a third operating phase during which the electric current supplying the stator is lower than during the first operating phase for an identical torque supplied by the electric motor.

[0012] The at least one piece of information relating to a temperature may further comprise information relating to a temperature of the rotor, and the at least one condition may further comprise the comparison of the temperature of the stator with the temperature of the rotor, then if the temperature of the stator is greater than or equal to the temperature of the rotor plus a second predefined offset, said third operating phase during which the electric current supplying the stator is lower than during the first operating phase for an identical torque supplied by the electric motor.

[0013] The first control law may comprise a control algorithm and a first set of parameters configured to parameterize the control algorithm, the second control law comprising the same control algorithm as the first control law and a second set of parameters configured to parameterize the control algorithm, the second set of parameters being different from the first set of parameters.

[0014] The at least one piece of information relating to a temperature may include an in- training relating to a temperature of a power stage of the electronic control device, and F at least one condition may comprise comparing the temperature of the power stage with a fourth predefined temperature threshold, then if the temperature of the power stage is less than or equal to the fourth temperature threshold, a fourth phase of operation of the electric motor during which the stator and the rotor are supplied with electric current by the electronic control device according to a fourth control law, a control frequency of the power stage being reduced during the fourth phase of operation compared to the first control law.

[0015] The control process may then include: - reception by the electronic control device of at least one item of information relating to a stator temperature and / or a rotor temperature, then - a comparison of the stator and / or rotor temperature with a sixth predefined temperature threshold, then if the stator and / or rotor temperature is greater than or equal to the sixth temperature threshold, - a sixth operating phase during which the stator and the rotor are supplied with an electric current by the electronic control device according to a sixth control law, different from the first control law and different from the second control law, to provide a torque strictly lower than a given torque setpoint.

[0016] The invention also relates to a powertrain for a motor vehicle comprising: - a synchronous electric motor, the electric motor comprising a stator and a wound rotor cooperating with the stator, - a means of detecting or calculating a temperature - an electronic control device configured to supply the stator and the rotor with an electric current, the electronic control device comprising: - a memory, the memory containing: - a control algorithm capable of calculating an electrical current setpoint for the stator and an electrical current setpoint for the rotor as a function of a torque setpoint expressed by the driver of the vehicle, - a first set of parameters configured to parameterize the control algorithm according to a first control law, and - at least one second set of parameters configured to parameterize the control algorithm according to a second control law different from the first control law, - a microcontroller configured to execute the first control law or the second control law as a function of at least one piece of information relating to a temperature temperature provided by said means for detecting or calculating a temperature of the rotor and / or the stator.

[0017] The invention also relates to a motor vehicle comprising a powertrain as defined previously and / or hardware and software means configured to implement a control method as defined previously.

[0018] The invention also relates to a computer program product comprising program code instructions recorded on a computer-readable medium for implementing the steps of the control method as defined above when said program operates on a computer.

[0019] The invention also relates to a data recording medium, readable by a computer, on which is recorded a computer program comprising program code instructions for implementing the control method as defined previously. Presentation of figures

[0020] These objects, characteristics and advantages of the present invention will be explained in detail in the following description of a particular embodiment made without limitation in relation to the attached figures among which:

[0021] [Fig. 1] is a schematic view of a motor vehicle according to one embodiment of the invention.

[0022] [Fig.2] is a block diagram of a method for controlling a wound rotor synchronous electric motor according to one embodiment of the invention. Detailed description

[0023] [Fig. 1] schematically illustrates a vehicle 1 according to one embodiment of the invention. In particular, the vehicle 1 is a motor vehicle, for example a passenger car, a utility vehicle, a truck or even a bus. The vehicle 1 comprises a powertrain 2 equipped with an electric motor 3 and an electronic control device 4 configured to control the electric motor 3. The electric motor 3 is intended to transmit a driving torque to drive wheels of the vehicle, so as to move the vehicle forward. The vehicle 1 also comprises an electrochemical battery 5 electrically connected to the electric motor 3 via the electronic control device 4.

[0024] The electric motor 3 is a wound rotor synchronous electric motor. It comprises a stator 6 and a rotor 7 rotatably mounted relative to the stator 6 along an axis of rotation 8. The stator 6 has the shape of a hollow cylinder of revolution inside which the rotor 7 is arranged.

[0025] The rotor 7 comprises a set of coils 9, that is to say a set of windings of electric wires intended to be traversed by an electric current. According to the embodiment presented, the rotor 7 comprises four coils 9 distributed around the axis of rotation 8. Alternatively, the number of coils of the rotor could be different. The coils 9 are arranged according to an alternation of North poles and South poles. The coils 9 can be wound around a core 10, for example in the shape of a cross. The rotor 7 is supplied with electric current by the electronic control device 4, via an electric power supply device comprising two rings and two brushes rubbing respectively on each of the two rings. The rotor 7 is intended to be supplied with a direct electric current Ir whose intensity is, for example, of the order of ten amperes.

[0026] The stator 6 also comprises a set of coils 11. According to the embodiment presented, the stator 6 comprises twelve coils 11 distributed around the axis of rotation 8. Alternatively, the number of coils 11 of the stator could be different. The stator 6 is supplied with electric current by the electronic control device 4, by a three-phase alternating electric current Is whose amplitude is, for example, of the order of a hundred amperes.

[0027] The electronic control device 4, also called an “inverter”, comprises a power stage 12 configured to supply the stator 6 and the rotor 7 with electric current. The power stage 12 is in particular configured to convert the direct electric current supplied by the electrochemical battery 5 into an alternating electric current Is suitable for supplying the stator 6, and into a direct electric current Ir suitable for supplying the rotor 7. A given balance between the electric current Ir supplying the rotor and the electric current Is supplying the stator makes it possible to achieve optimal efficiency of the electric motor 3.

[0028] The vehicle 1 also comprises a data bus 13, in particular a CAN type data bus 13, and the electronic control device 4 comprises a module 14 for reading the data transmitted on the data bus 13. The electronic control device 4 is thus able to receive, in real time, a torque instruction Ce expressed by a driver of the vehicle, for example by means of an accelerator pedal 24.

[0029] The powertrain 2 also comprises at least one means 21 for detecting or calculating a temperature. The means 21 for detecting or calculating a temperature may take different forms. The means 21 for detecting or calculating a temperature may comprise at least one temperature sensor. The at least one temperature sensor may be configured to measure the temperature of at least one element of the powertrain 2, in particular an element of the stator 6, and / or at least one element of the rotor 7. Alternatively or in addition, the at least one temperature sensor may be configured to measure the temperature of a cooling fluid of the electric motor, for example an oil temperature. Alterna- Alternatively or additionally, at least one temperature sensor may be configured to measure the temperature of the electrochemical battery 5. Alternatively or additionally, the at least one temperature sensor may be configured to measure the temperature of the electronic control device 4, and in particular of the power stage 12. These different temperature sensors may be connected to the electronic control device 4 via the data bus 13 or by any other type of connecting means. Alternatively or additionally, the means for detecting or calculating a temperature 21 may be configured to estimate a temperature of the stator 6 and / or of the rotor 7 and / or of the electrochemical battery 5 and / or of the power stage 12 from measurements of other physical quantities, for example by integrating the electric current consumed by the rotor and / or by the stator.In this case, the electronic control device 4 may comprise a calculation module configured to provide such temperature estimates. Alternatively, such a calculation module could be integrated into another electronic device of the vehicle to which the electronic control device 4 is connected via the data bus 13 or by any other type of connection means.

[0030] In the remainder of the description, it is assumed that the powertrain is equipped with a first temperature sensor 22 configured to measure the temperature of the stator 6, and a second temperature sensor 23 configured to measure the temperature of the rotor 7. It is also assumed that these temperature sensors 22, 23 are connected to the electronic control device 4 by means of the data bus 13. The electronic control device 4 is thus able to receive, permanently, information relating to the temperature Ts of the stator 6 and information relating to the temperature Tr of the rotor 7.

[0031] The electronic control device 4 further comprises a memory 15 and a microprocessor 16. The microprocessor 16 is connected to the power stage 12, to the memory 15 and to the module 14 for reading the data transmitted on the data bus 13.

[0032] In the memory 15 is recorded a control algorithm 17. The control algorithm 17 comprises a series of logic steps, or in other words a succession of logic instructions, intended to calculate electrical current setpoints for the stator and for the rotor from a set of input quantities including a torque setpoint Ce expressed by the driver. The control algorithm 17 can also take into account other input quantities, for example an engine speed or a voltage of the electrochemical battery. These other input quantities can possibly be supplied to the electronic control device 4 by the data bus 13.

[0033] In memory 15 are also recorded a first set of parameters 18, a second set of parameters 19, and a third set of parameters 20. The first set of parameters 18, or first mapping 18, is configured to parameterize the control algorithm 17 according to a first control law. The second set of parameters 19, or second mapping 19, is configured to parameterize the control algorithm 17 according to a second control law, different from the first control law. The third set of parameters 20, or third mapping 20, is configured to parameterize the control algorithm 17 according to a third control law, different from the first control law and different from the second control law.

[0034] A control law is therefore defined as the combination of the control algorithm 17 with a set of parameters 18, 19 or 20. A control law is thus configured to calculate an electric current setpoint for the stator and an electric current setpoint for the rotor, as a function of a torque setpoint Ce expressed by the driver of the vehicle.

[0035] The parameter sets 18, 19 and 20 each comprise a set of numerical data assigning particular numerical values ​​to variables used by the control algorithm 17. These variables correspond, for example, to thresholds or coefficients used by the control algorithm 17. In certain cases, the numerical values ​​may take the form of matrices. The three parameter sets 18, 19 and 20 are intended to substitute for each other, that is to say that either the control algorithm 17 is combined with the first parameter set 18, or the control algorithm 17 is combined with the second parameter set 19, or the control algorithm 17 is combined with the third parameter set 20. The control algorithm 17 cannot be combined simultaneously with two parameter sets.The use of several parameter sets makes it possible to obtain several control laws for controlling the electric motor 3, without modifying the control algorithm 17. The parameter sets 18, 19, 20 are different from each other in that at least some of the numerical values ​​assigned to the variables are different between the different parameter sets.

[0036] Note that the enumeration terms such as "first", "second" and "third" used in this description do not in themselves confer any technical characteristics on the elements to which they relate. They are intended only to distinguish different elements bearing the same name.

[0037] Alternatively, the memory 15 could also contain only two sets of parameters, for example only the first set of parameters and the second set of parameters or only the first set of parameters and the third set of parameters. The memory 15 could also contain a larger number of sets of parameters for combination with the control algorithm 17, for example four, five, or six different parameter sets. However, defining each parameter set requires a fairly long and tedious calibration phase and validations. Thus, memory 15 can preferably contain a maximum of ten different parameter sets.

[0038] The first set of parameters 18 may correspond to an optimal calibration of the electric motor 3, that is to say a calibration which makes it possible to achieve the best possible efficiency with the electric motor 3 or an efficiency close to the best possible efficiency. The efficiency of the electric motor designates the ratio of the electrical power supplied to the stator and to the rotor to the mechanical torque supplied by the rotor to drive the drive wheels of the vehicle.

[0039] The second set of parameters 19 may correspond to a non-optimal calibration of the electric motor 3, that is to say a calibration with which the efficiency of the electric motor 3 is strictly lower than the efficiency obtained with the first set of parameters 18. In particular, for the same torque supplied by the electric motor 3, the electric current Ir supplying the rotor may be lower and the amplitude of the electric current Is supplying the stator may be higher with the second control law compared to the first control law. When the electric motor is controlled with the second control law, it consumes on average a higher electrical power than that which it would consume if it were controlled with the first control law for an identical torque supplied by the electric motor.The second control law, however, allows the driver's torque request to be satisfied in the same way as the first control law. The second control law does not correspond to an operating mode in which the torque provided by the electric motor is limited. Vehicle users therefore do not perceive any difference in performance between the first control law and the second control law.

[0040] The third set of parameters 20 may also correspond to a non-optimal calibration of the electric motor 3, that is to say a calibration with which the efficiency of the electric motor 3 is strictly lower than the efficiency obtained with the first set of parameters 18. In particular, for the same torque supplied by the electric motor 3, the electric current Ir supplying the rotor may be higher and the amplitude of the electric current Is supplying the stator may be lower with the third control law compared to the first control law. When the electric motor is controlled with the third control law, it consumes on average a higher electrical power than that which it would consume if it were controlled with the first control law for an identical torque supplied by the electric motor.The third control law nevertheless allows the torque request expressed by the driver to be satisfied in the same way as the first law. control. The third control law does not correspond to an operating mode in which the torque supplied by the electric motor is limited. Vehicle users therefore do not perceive any difference in performance between the first control law and the third control law.

[0041] In the event that the memory contains a fourth set of parameters, this could be configured so that a control frequency of the power stage 12 is lower with the fourth control law compared to the first control law.

[0042] The memory 15 of the electronic control device 4 is a data recording medium on which is recorded a computer program comprising program code instructions for implementing a method for controlling the electric motor 3 according to one embodiment of the invention. The microprocessor 16 is capable of executing this computer program. The power stage 12 is configured to supply the stator 6 and the rotor 7 with an electric current Is, Ir respecting the instructions calculated by the microprocessor 16.

[0043] An embodiment of this control method is now described in relation to [Fig.2],

[0044] In a first phase PI, the electric motor 3 operates normally. A driver of the vehicle 1 expresses a torque setpoint Ce by pressing the accelerator pedal 24 of the vehicle. This torque setpoint is transmitted on the data bus 13 and read by the module 14 of the electronic control device 4. The electronic control device 4 then calculates the electrical supply currents of the stator 6 and the rotor 7 of the electric motor 3 to satisfy the torque setpoint, using the first control law, that is to say by combining the control algorithm 17 with the first set of parameters 18. The energy efficiency of the electric motor 3 is then maximum, or close to its maximum value. During this first phase PI, the torque setpoint expressed by the driver is likely to vary.The electronic control device 4 then adapts the electrical supply currents of the stator 6 and the rotor 7 according to the first control law, instantaneously, to satisfy the torque setpoint.

[0045] During the first phase PI, the temperature of the electric motor 3 is also monitored. In particular, the electronic control device 4 regularly receives information relating to the temperature Ts of the stator 6 provided by the first temperature sensor 22, and information relating to the temperature Tr of the rotor 7 provided by the second temperature sensor 23. The electronic control device 4 thus has the temperatures Ts and Tr permanently available and these temperatures are regularly updated.

[0046] We then verify two first conditions Ci l and C12 relating to the temperatures Ts and Tr. Condition C11 consists of comparing the rotor temperature Tr with a first predefined temperature threshold. Condition C12 consists of comparing the rotor temperature Tr with the stator temperature Ts plus a first predefined offset. The first offset can be equal to a negative value or a positive value, or even equal to zero. The first offset is used to make the temperatures Ts and Tr comparable. Indeed, the temperature thresholds from which the stator or the rotor are likely to be damaged are potentially different.

[0047] Condition Cl 1 is verified if the rotor temperature Tr is strictly higher than the first temperature threshold. Condition C 12 is verified if the rotor temperature Tr is strictly higher than the stator temperature Ts plus the first offset. When both conditions C11 and C12 are verified, it is considered that the rotor 7 has reached a critical temperature which threatens its proper functioning and / or which risks damaging the rotor.

[0048] If the two conditions C11 and C12 are verified, then a second phase P2 is started during which the electronic control device 4 calculates the electrical supply currents of the stator 6 and the rotor 7 of the electric motor 3 to satisfy the torque setpoint, using the second control law, that is to say by combining the control algorithm 17 with the second set of parameters 19.

[0049] According to this second control law, the electric current Is supplying the stator 6 is higher and the electric current Ir supplying the rotor 7 is lower than during the first phase for the same torque supplied by the electric motor 3. The efficiency of the electric motor 3 is certainly not optimized, but the reduction of the electric current supplying the rotor makes it possible to lower the temperature of the latter. In return, the temperature of the stator is likely to increase. This is less of a problem since it is the temperature of the rotor which is critical, and not that of the stator. The use of the second control law makes it possible to maintain a non-degraded operating mode for a longer time in which the torque supplied by the electric motor is not limited.

[0050] According to an alternative embodiment of the invention, only one or the other of the two conditions C11 and C12 could be sufficient to pass from the first phase of PI to the second phase P2, that is to say to pass from an operation with the first control law to an operation with the second control law.

[0051] Two second conditions C21 and C22 relating to the temperatures Ts and Tr are also verified. Condition C21 consists of comparing the stator temperature Ts with a second predefined temperature threshold. Condition C22 consists of comparing the stator temperature Ts with the rotor temperature Tr plus a second predefined offset. The second offset can be equal to a negative value or a positive value, or even equal to zero. As for the first offset, the second offset is used to make the temperatures Ts and Tr comparable.

[0052] Condition C21 is verified if the stator temperature Ts is strictly higher than the second temperature threshold. Condition C22 is verified if the stator temperature Ts is strictly higher than the rotor temperature Tr plus the second offset. When both conditions C21 and C22 are verified, it is considered that the stator 6 has reached a critical temperature which threatens its proper functioning and / or which risks damaging the stator.

[0053] If the two conditions C21 and C22 are verified, then a third phase P3 is started during which the electronic control device 4 calculates the electrical supply currents of the stator 6 and the rotor 7 of the electric motor 3 to satisfy the torque setpoint, using the third control law, that is to say by combining the control algorithm 17 with the third set of parameters 20.

[0054] According to this third control law, the supply current of stator 6 is lower and the supply current of rotor 7 is higher than during the first phase for the same torque supplied by the electric motor. The efficiency of electric motor 3 is certainly not optimized, but the reduction of the supply current of the stator makes it possible to lower the temperature of the latter. In return, the temperature of the rotor is likely to increase. This is less of a problem since it is the temperature of the stator which is critical, and not that of the rotor. The use of the third control law makes it possible to maintain a non-degraded operating mode for a longer time in which the torque supplied by the electric motor is not limited.

[0055] As previously, according to an alternative embodiment of the invention, only one or other of the two conditions C21 and C22 could be sufficient to pass from the first phase of PI to the third phase P3, that is to say to pass from an operation with the first control law to an operation with the third control law.

[0056] According to the embodiment presented, if at least one of the two conditions C11 or C12 is not verified or if at least one of the two conditions C21 or C22 is not verified, then the first phase PI is continued.

[0057] According to another embodiment variant, the memory 15 could contain only the second set of parameters 19 or only the third set of parameters 20. In this hypothesis, the method described above would be adapted so as to control the electric motor only according to the second control law or according to the third control law.

[0058] According to another alternative embodiment of the invention, freely combinable with the embodiments previously described, a comparison of the temperature of the power stage 12 with a fourth temperature threshold could be provided. If the temperature of the power stage 12 is strictly greater than the fourth threshold, a fourth phase of operation of the electric motor could be started during which the electronic control device 4 calculates the electrical supply currents of the stator 6 and the rotor 7 of the electric motor 3 to satisfy the torque setpoint, using a fourth control law, in which the control frequency of the power stage 12 is reduced compared to the first control law. It is thus possible to reduce the temperature of the power stage 12.

[0059] According to another alternative embodiment of the invention, freely combinable with the embodiments described above, it would be possible to provide a comparison of the temperature of the electrochemical battery 5 with a fifth temperature threshold. If the temperature of the electrochemical battery 5 is strictly lower than the fifth threshold, a fifth operating phase of the electric motor could be started during which the electronic control device 4 calculates the electrical supply currents of the stator 6 and the rotor 7 of the electric motor 3 to satisfy the torque setpoint, using a fifth control law, in which the stator supply current and / or the rotor supply current is increased compared to the first control law. By supplying more electrical current, the electrochemical battery 5 can thus warm up more easily.Indeed, with a higher supply current, the temperature of the electric motor 3 will increase, which will increase the temperature of the coolant, and further the temperature of the electrochemical battery 5 (which will be heated by this liquid). Similarly, this fifth operating mode could be envisaged when a heat input is desirable for an element of the vehicle likely to be heated by an increased consumption of electric current at the rotor and / or at the stator. This operating mode could also be envisaged to heat more quickly the oil circulating around the electric motor.

[0060] In addition to the various embodiments previously described, it is also possible to provide a comparison of the temperature of the rotor 7 with a sixth temperature threshold, strictly higher than the first temperature threshold. If the temperature of the rotor is strictly higher than the sixth threshold, a sixth operating phase could be started, corresponding to a degraded operating phase, during which the torque supplied by the electric motor is limited so as to prevent the rotor from being damaged. Similarly, it is also possible to provide a comparison of the temperature of the stator 6 with a seventh temperature threshold, strictly higher than the second temperature threshold. If the temperature of the stator is strictly higher than the seventh threshold, said degraded operating phase could be started during which the torque supplied by the electric motor is limited. so as to prevent the stator from being damaged.

[0061] Finally, thanks to the invention, there is provided a method for controlling a wound rotor electric motor which makes it possible to extend, in the event of a high temperature of the latter, an operating mode in which the torque setpoint expressed by the driver is fully satisfied. In the event that the temperature of the electric motor continues to increase despite the reduction of the electric current flowing in the rotor or in the stator, it remains possible to switch the electric motor into a degraded mode in which the torque setpoint of the driver will be limited. This switch is nevertheless delayed, or even completely avoided, compared to the control methods known from the state of the art.

Claims

Claims

1. Method for controlling a synchronous electric motor (3) for a motor vehicle (1), by an electronic control device (4), the electric motor comprising a stator (6) and a wound rotor (7) cooperating with the stator, the stator and the rotor each being powered by an electric current supplied by the electronic control device, characterized in that it comprises: - a first phase (PI) of operation of the electric motor during which the stator and the rotor are each supplied by an electric current (Is, Ir) supplied by the electronic control device according to a first control law configured to satisfy a torque setpoint (Ce), then - reception by the electronic control device of at least one piece of information relating to a temperature (Ts, Tr), then - a verification of at least one condition (Cil, Cl 2) dependent on at least one piece of information relating to a temperature, then if the at least one condition is verified, - a second phase (P2) of operation of the electric motor during which the stator and the rotor are each powered by an electric current supplied by the electronic control device according to a second control law configured to satisfy a torque setpoint, the second control law being different from the first control law, an electric current (Ir) supplying the rotor being different during the second phase of operation compared to the first phase of operation for an identical torque supplied by the electric motor and / or an electric current (Is) supplying the stator being different during the second phase of operation compared to the first phase of operation for an identical torque supplied by the electric motor.

2. Control method according to the preceding claim, characterized in that the at least one piece of information relating to a temperature comprises information relating to a temperature of the rotor (Tr), and in that the at least one condition comprises the comparison (Cl 1) of the temperature of the rotor with a first predefined temperature threshold, then if the temperature of the rotor is greater than or equal to the first temperature threshold, a second phase (P2) of operation during which the electric current (Ir) supplying the rotor is lower than during the first phase (PI) of operation for an identical torque supplied by the electric motor.

3. Control method according to the preceding claim, characterized in that the at least one item of information relating to a temperature further comprises information relating to a stator temperature (Ts), and in that the at least one condition further comprises the comparison (C12) of the rotor temperature (Tr) with the stator temperature, then if the rotor temperature is greater than or equal to the stator temperature plus a first predefined offset, said second operating phase (P2) during which the electric current (Ir) supplying the rotor is lower than during the first operating phase for an identical torque supplied by the electric motor.

4. Control method according to one of the preceding claims, characterized in that the at least one piece of information relating to a temperature comprises information relating to a stator temperature (Ts), and in that the at least one condition comprises the comparison (C21) of the stator temperature with a second predefined temperature threshold, then if the stator temperature is greater than or equal to the second temperature threshold, a third operating phase (P3) during which the electric current (Is) supplying the stator is lower than during the first operating phase for an identical torque supplied by the electric motor.

5. Control method according to the preceding claim, characterized in that the at least one piece of information relating to a temperature further comprises information relating to a rotor temperature (Tr), and in that the at least one condition further comprises the comparison (C22) of the stator temperature with the rotor temperature (Tr), then if the stator temperature is greater than or equal to the rotor temperature plus a second predefined offset, said third phase (P3) of operation during which the electric current (Is) supplying the stator is lower than during the first phase of operation for an identical torque supplied by the electric motor.

6. Control method according to one of the preceding claims, characterized in that the first control law comprises a control algorithm (17) and a first set of parameters (18) configured to parameterize the control algorithm, the second control law comprising the same control algorithm (17) as the first control law and a second set of parameters (19) configured to pa- resize the control algorithm, the second set of parameters being different from the first set of parameters.

7. Control method according to one of the preceding claims, characterized in that the at least one item of information relating to a temperature comprises information relating to a temperature of a power stage (12) of the electronic control device (4), and in that the at least one condition comprises the comparison of the temperature of the power stage with a fourth predefined temperature threshold, then if the temperature of the power stage is less than or equal to the fourth temperature threshold, a fourth phase of operation of the electric motor during which the stator and the rotor are supplied with electric current by the electronic control device according to a fourth control law, a control frequency of the power stage being reduced during the fourth phase of operation compared to the first control law.

8. Control method according to one of the preceding claims, characterized in that it then comprises: - reception by the electronic control device (4) of at least one item of information relating to a temperature (T s) of the stator (6) and / or a temperature (Tr) of the rotor (7), then - a comparison of the stator and / or rotor temperature with a sixth predefined temperature threshold, then if the stator and / or rotor temperature is greater than or equal to the sixth temperature threshold, - a sixth operating phase during which the stator and the rotor are supplied with an electric current by the electronic control device according to a sixth control law, different from the first control law and different from the second control law, to provide a torque strictly lower than a given torque setpoint.

9. Powertrain (2) for a motor vehicle (1) comprising: a synchronous electric motor (3), the electric motor comprising a stator (5) and a wound rotor (7) cooperating with the stator, a means for detecting or calculating a temperature (21, 22, • an electronic control device (4) configured to supply the stator and the rotor with an electric current, the electronic control device comprising: • a memory (15), the memory containing: - a control algorithm (17) capable of calculating an electric current setpoint for the stator and an electric current setpoint for the rotor as a function of a torque setpoint (Ce) expressed by the driver of the vehicle, - a first set of parameters (18) configured to parameterize the control algorithm according to a first control law, and - at least one second set of parameters (19) configured to parameterize the control algorithm according to a second control law different from the first control law, • a microcontroller (16) configured to execute the first control law or the second control law as a function of at least one item of information relating to a temperature (Tr, Ts) provided by said means for detecting or calculating a temperature of the rotor and / or the stator.

10. Motor vehicle (1) comprising a powertrain (2) according to the preceding claim and / or hardware and software means configured to implement a control method according to one of claims 1 to 9.

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