CONTROL METHOD AND ASSOCIATED CONTROL SYSTEM

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for controlling a three-phase synchronous-reluctant or permanent magnet synchronous rotating machine.

[0002] The invention also relates to a control system

[0003] The invention applies to the field of controlling rotating machines, in particular the control of permanent magnet synchronous machines and synchro-reluctant machines. STATE OF THE PRIOR ART

[0004] It is known to use rotating machines such as permanent magnet synchronous machines or synchro-reluctant machines, in particular permanent magnet-assisted synchro-reluctant machines. Such rotating machines are, for example, used in the field of propulsion, for example for generating engine torque on board a vehicle such as an automobile.

[0005] Document FR 3 051 296 A1 describes, for example, a synchro-reluctant machine assisted by permanent magnets

[0006] Such rotating machines are advantageous in that, when a so-called "voltage saturation" regime is reached, it is still possible to increase the rotational speed of the rotor of the machine while significantly limiting the decrease in the mechanical torque provided by the rotating machine, by carrying out an operation called "defluxing". Such a decrease in the mechanical torque provided by the rotating machine, when the rotational speed is increased, is a common undesirable phenomenon occurring when such defluxing is not implemented.

[0007] For the purposes of the present invention, the term "voltage saturation regime" means a situation in which the voltage applied to the terminals of the rotating machine becomes equal to a maximum available voltage, the value of which depends on the electrical installation to which the rotating machine is connected, so that it is no longer possible to increase the supply voltage of the rotating machine.

[0008] Furthermore, by "defluxing" is meant, within the meaning of the present invention, a method for controlling such a rotating machine, comprising an injection of current at the level of the phases, that is to say the windings, of the stator of the rotating machine in order to compensate, at least in part, the magnetic field generated by the magnets of the rotor of said rotating machine.

[0009] Such a control method generally comprises the calculation of so-called "direct" and "quadrature" currents and voltages, which are virtual currents and voltages expressed in a rotating frame linked to the rotor, and the implementation of two servocontrols, one relating to the so-called direct quantities, and the other relating to the so-called "quadrature" quantities, in order to determine the voltages to be applied to each phase of the rotating machine.

[0010] Since the rotating machines mentioned above are synchronous, implementing defluxing involves synchronization between the rotating magnetic fields of the stator and the rotor. The angle formed between the respective directions of the magnetic field of the rotor magnets and the currents expressed in the rotating frame linked to the rotor is called the "defluxing angle".

[0011] Defluxing therefore consists of generating a magnetic field induced by the currents in the stator to compensate, at least in part, for the effect of the rotor's magnetic field, with the aim of reducing the voltage at the terminals of the rotating machine. In this way, the rotating machine is able to absorb more current, and therefore to provide a greater mechanical torque at the same speed, than when such defluxing does not take place. Such defluxing is therefore advantageous, insofar as it limits the loss of mechanical torque produced by the rotating machine and increases the rotational speed of the rotor at a given torque value, without the voltage at the terminals of the rotating machine exceeding the maximum voltage. Thus, even in the voltage saturation regime, the power consumed by the rotating machine is maintained equal to a higher power than in the absence of defluxing, which results in better performance.

[0012] In particular, synchro-reluctant machines have significant defluxing capabilities, which allows them to benefit from a large part of their power up to their maximum speed.

[0013] However, such an ordering method is not entirely satisfactory.

[0014] Indeed, in a conventional control method as described previously, the efficiency of the electric machine is not satisfactory.

[0015] This is due in particular to the fact that, in such a usual control method, the maximum available voltage is not applied to the terminals of the rotating machine. This is due to the fact that, if the voltage applied to the electrical machine were to be maximum, only the phase of said voltage would be a degree of freedom for the control of the rotating machine, which would pose stability problems.

[0016] As a result, in a conventional control method as described above, the choice is generally made to apply a voltage lower than the maximum available voltage to the rotating machine, in order to benefit from two degrees of freedom for the control (phase of the voltage and standard of the voltage applied to the terminals of the rotating machine).

[0017] Such a choice is made to the detriment of the efficiency of the rotating machine.

[0018] Patent applications FR 2994355 A1, WO 03 / 084049 A1, EP 1868288 A1, US 2016 / 0359442 A1, FR 3012270 A1, describe different systems for controlling the electromagnetic torque of an electrical machine.

[0019] An aim of the invention is therefore to propose a control method which results in less degradation of the efficiency of the rotating machine, in particular during defluxing, while reducing the instability of the mechanical torque delivered during said defluxing, and allowing maximum use of the available voltage.

[0020] The invention is defined by the appended claims. To this end, the invention relates to a method of the aforementioned type, comprising the following steps: measuring a current flowing in each of the phases of a stator of the rotating machine; first calculating, by means of a single proportional-integral regulator, a switching control signal for controlling an inverter, as a function of each measured current, and a target value of a mechanical torque supplied by the rotating machine or a target value of an angular speed of a rotor of the rotating machine relative to the stator, the inverter being configured to convey electrical energy between a continuous source of electrical energy and each phase of the stator of the rotating machine; controlling the inverter by means of the calculated switching control signal.

[0021] Indeed, such a method, thanks to the use of a single proportional-integral regulator, reduces the coupling of direct and quadrature quantities between them, which results in less non-linearities in the control, and therefore allows control of the rotating machine in which the maximum available voltage is applied to the terminals of the rotating machine, without any problems of lack of stability arising. Such a method is therefore capable of increasing the efficiency of the rotating machine during defluxing.

[0022] The process also includes: the first calculation includes the determination of a quadrature voltage setpoint according to: v q , ref = K ′ p , q i 0 − i ref + K ′ i , q ∫ t 0 t f i 0 − i ref dt where vq,ref is the quadrature voltage setpoint; K' p,q and K' i,q are predetermined coefficients of the single proportional-integral corrector; i 0 is a quantity defined as i 0 = i q 2 + i d 2 ; i ref is a quantity defined as i ref = i q , ref 2 + i d , ref 2 ; t 0 is a predetermined initial time; tf is a predetermined final time subsequent to the predetermined initial time; id and iq are respectively a measured direct current and a measured quadrature current, dependent on each measured current; id,ref and iq,ref are respectively a direct current setpoint and a quadrature current setpoint, each representative of the target value of the mechanical torque supplied by the rotating machine or of the target value of the angular speed of the rotor of the rotating machine relative to the stator; the commutation control signal being a function of the quadrature voltage setpoint; the first calculation further comprises determining a direct voltage setpoint according to: v d , ref = v lim 2 − v q , ref 2 where vd,ref is the forward voltage setpoint; v lim is a limit voltage defined as v lim = αv DC; α being a predetermined modulation index of the inverter; the switching control signal being, moreover, a function of the forward voltage setpoint; the modulation index has a value between 1 / √3 and 1; the predetermined coefficients of the single proportional-integral corrector are chosen so that the value of the determined quadrature voltage setpoint is bounded, preferably less than or equal to a limit voltage defined as: v lim = αv DC where v lim is the limit voltage; α is a predetermined modulation index of the inverter; and v DC is a voltage between the source and a potential reference; the first calculation is implemented if a predetermined condition is verified;the method comprises determining a direct voltage setpoint and a quadrature voltage setpoint dependent on each measured current, the predetermined condition being verified if the sum of the squares of the direct voltage setpoint and the quadrature voltage setpoint is greater than or equal to a predetermined fraction of the square of a predetermined limit voltage, advantageously greater than or equal to 75% of the square of the predetermined limit voltage, for example greater than or equal to 90% of the square of the predetermined limit voltage, or even equal to the square of the predetermined limit voltage;the direct voltage setpoint and the quadrature voltage setpoint are determined during a second calculation of the switching control signal, distinct from the first calculation, the predetermined condition being verified if, during the implementation of the second calculation, the sum of the squares of the direct voltage setpoint and the quadrature voltage setpoint becomes greater than or equal to the predetermined fraction of the square of a predetermined limit voltage, or equal to the square of the predetermined limit voltage; the predetermined condition is verified if the angular speed of the rotor of the rotating machine relative to the stator is greater than or equal to a predetermined base speed. ;

[0023] Furthermore, the invention relates to a control system for a three-phase synchronous-reluctant or synchronous rotating machine with permanent magnets, comprising: a current sensor configured to measure a current flowing in each of the phases of a stator of the rotating machine; an inverter configured to convey electrical energy between a continuous source of electrical energy and each phase of the stator of the rotating machine; and a computer configured to carry out, by implementing a single proportional-integral regulator, a first calculation of a switching control signal for controlling the inverter, as a function of each current measured by the current sensor, and of a quantity representative of a target value of a mechanical torque supplied by the rotating machine or of a target value of an angular speed of a rotor of the rotating machine relative to the stator, the calculator being, furthermore, configured to apply, to the inverter, the calculated switching control signal, in order to control the inverter.

[0024] According to another advantageous aspect of the invention, the control system comprises the following characteristic: the computer is configured to implement the control method as defined above, with the exception of the measurement step. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention will be better understood with the aid of the following description, given solely by way of non-limiting example and made with reference to the single appended drawing, in which: [ Fig. 1 ] there figure 1 is a schematic representation of a control system according to the invention associated with a three-phase synchronous-reluctant or permanent magnet synchronous rotating machine. DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0026] On the figure 1an installation 2 is shown comprising a rotating machine 4 associated, for its control, with a control system 6 according to the invention. The installation 2 also comprises a source 8 of electrical energy, such as a direct voltage bus.

[0027] The rotating machine 4 is a three-phase rotating machine, synchronous with permanent magnets or synchro-reluctant, in particular a three-phase rotating machine synchro-reluctant assisted by permanent magnets.

[0028] The rotating machine 4 has three inputs, designated respectively by the letters A, B, C. Each input A, B, C corresponds to a phase of a stator of the rotating machine 4.

[0029] Subsequently, a quantity relating to a given input of the rotating machine 4 will present, as an index, the letter relating to said input.

[0030] The control system 6 is intended to control, over time, the power supply of the rotating machine 4 as a function of target values ​​and / or measured values ​​of predetermined quantities, which will be described later.

[0031] The control system 6 comprises an inverter 10, an angular position sensor 12, a current sensor 14, a voltage sensor 16 and a computer 18.

[0032] The inverter 10 is configured to route electrical energy between the source 8 and the rotating machine 4. More specifically, the inverter 10 is configured to route electrical energy between the source 8 and each phase of the stator of the rotating machine 4.

[0033] The inverter 10 comprises a first input connected to the source 8, and three outputs, each connected to a corresponding phase of the stator of the rotating machine 4. The inverter 10 further comprises a second input electrically connected to an output of the computer 18, so that the inverter 10 is configured to route electrical energy between the source 8 and the rotating machine 4 as a function of a switching control signal applied by the computer 18 to the second input of the inverter 10.

[0034] Preferably, the switching control signal is such that the inverter 10 routes electrical energy from the source 8 to the rotating machine 4 so that the rotating machine 4 has an operation commonly called a “motor”.

[0035] The angular position sensor 12 is configured to measure the angular position, denoted θ, of a rotor (not shown) of the rotating machine 4 relative to the stator, and to deliver an angular position signal representative of the measured value of the angular position θ of the rotor of the rotating machine 4.

[0036] Furthermore, the angular position sensor 12 is configured to apply the angular position signal to a corresponding input of the computer 18.

[0037] The current sensor 14 is configured to measure the intensity, denoted i A , i B , i C , of the current delivered by each of the outputs of the inverter 10 and supplying each corresponding phase of the stator of the rotating machine 4. The current sensor 14 is also configured to deliver an intensity signal representative of the measured value of each intensity i A , i B , i C .

[0038] Furthermore, the current sensor 14 is configured to apply the current signal to a corresponding input of the computer 18.

[0039] The voltage sensor 16 is configured to measure the voltage, denoted v DC , between the source 8 and a potential reference, and to deliver a voltage signal representative of the measured value of the voltage v DC . In other words, the voltage sensor 16 is configured to measure the voltage v DC between the first input of the inverter 10 and the potential reference.

[0040] Furthermore, the voltage sensor 16 is configured to apply the voltage signal to a corresponding input of the computer 18.

[0041] The computer 18 is configured to control the operation of the inverter 10 according to the value of a target torque T ref desired at the output of the rotating machine 4. More precisely, the computer 18 is configured to control the operation of the inverter 10 according to the target torque T ref , and at least one of the angular position signal, the intensity signal and the voltage signal.

[0042] The calculator 18 comprises a current setpoint calculation member 20, a current control member 22, a first transformation member 24, a second transformation member 26 and a pulse width modulation member 28.

[0043] The second transformation member 26 is configured to calculate a measured direct current id and a measured quadrature current iq. In particular, the second transformation member 26 is configured to calculate the measured direct current id and the measured quadrature current iq from the intensity signal delivered by the current sensor 14.

[0044] More precisely, the second transformation member 26 is configured to calculate the measured direct current id and the measured quadrature current iq by applying a Park transformation to the intensities i A , i B , i C measured by the current sensor 14. Such a transformation is carried out by applying the following relation (1): i d i q = cos θ e cos θ e − 2 π 3 cos θ e + 2 π 3 − sin θ e − sin θ e − 2 π 3 − sin θ e + 2 π 3 i A i B i C where θ e is an electrical angular position of the rotor relative to the stator of the rotating machine 4, equal to pθ, p being the number of pairs of poles of the rotating machine 4.

[0045] Such a transformation is intended to simplify the control by reducing, from quantities represented in relation to the three fixed windings of the stator, to virtual quantities associated with only two fictitious windings linked to the rotor, in quadrature with respect to each other, and which move at the same angular speed as the rotor. For example, the currents bearing the indices "d" and "q" will correspond to the currents flowing respectively in each of the two fictitious windings, while the voltages bearing the indices "d" and "q" will correspond to voltages at the terminals of each of the two fictitious windings, respectively.

[0046] The current setpoint calculation unit 20 is configured to calculate a direct current setpoint id,ref and a quadrature current setpoint iq,ref.

[0047] The direct current setpoint id,ref and the quadrature current setpoint iq,ref are quantities representative of target values ​​for the intensities i A , i B , i C , that is to say of setpoints for the intensities i A , i B , i C . In particular, the direct current setpoint id,ref and the quadrature current setpoint iq,ref are linked in a unique way to the said target values ​​of the intensities i A , i B , i C .

[0048] The current setpoint calculation member 20 is configured to calculate the direct current setpoint id,ref and the quadrature current setpoint iq,ref as a function of the target torque T ref , the angular position signal received from the angular position sensor 12 and the voltage signal received from the voltage sensor 16.

[0049] More precisely, the current setpoint calculation member 20 is configured to calculate the direct current setpoint id,ref and the quadrature current setpoint iq,ref so that the direct current setpoint id,ref and the quadrature current setpoint iq,ref satisfy the following relationship (2): T ref = p 3 2 Φi q , ref + p L d − L q i d , ref i q , ref where p is the number of pole pairs of the rotating machine 4;

[0050] L d and L q are the inductances of the rotating machine 4, respectively in the so-called “direct” and “quadrature” axes of the rotating machine; and and Φ is the flux of the permanent magnets in the rotating frame linked to the rotor, and more precisely in an axis called the “direct axis” of said rotating frame.

[0051] Furthermore, the direct current setpoint id,ref and the quadrature current setpoint iq,ref are, for example, obtained by mapping from predetermined charts, or by means of an equation allowing the joule losses to be minimized given by R( i 2< d,ref + i 2< q,ref ), R being the resistance of a phase of the rotating machine 4.

[0052] The concepts of direct axis inductance L d and quadrature axis inductance L q , as well as the determination of the value of such inductances L d , L q , are known per se. The value of such inductances generally depends on the value of each of the direct current id and the quadrature current iq .

[0053] The current control member 22 is configured to calculate a direct voltage setpoint vd,ref and a quadrature voltage setpoint vq,ref.

[0054] The direct voltage setpoint vd,ref and the quadrature voltage setpoint vq,ref are quantities representative of target values ​​for the voltages v A , v B , v C at the terminals of the stator windings, i.e. of setpoints for the voltages v A , v B , v C . In particular, the direct voltage setpoint vd,ref and the quadrature voltage setpoint vq,ref are linked in a unique way to the said target values ​​of the voltages v A , v B , v C .

[0055] In particular, the current control member 22 is configured to determine the direct voltage setpoint vd,ref and the quadrature voltage setpoint vq,ref as a function of the direct current setpoint id,ref and the quadrature current setpoint iq,ref calculated by the calculation member 20, as well as from the measured direct current id and the measured quadrature current iq previously described.

[0056] More specifically, the current control member 22 is configured to calculate the direct voltage setpoint vd,ref and the quadrature voltage setpoint vq,ref according to one or the other of a first calculation mode and a second calculation mode, depending on whether a predetermined condition is met or not.

[0057] If the predetermined condition is met, the current control member 22 is configured to calculate the direct voltage setpoint vd,ref and the quadrature voltage setpoint vq,ref according to the first calculation mode, by implementing a single proportional-integral corrector (also called a “proportional-integral regulator”). In this case, the current control member 22 is configured to calculate the direct voltage setpoint vd,ref and the quadrature voltage setpoint vq,ref by implementing the following relationships (3), (4): v q , ref = K ′ p , q i 0 − i ref + K ′ i , q ∫ t 0 t f i 0 − i ref dt v d , ref = v lim 2 − v q , ref 2 where K' p,q and K' i,q are two predetermined coefficients of the proportional-integral corrector associated, in the first calculation mode, with the voltage setpoint in quadrature; i 0 is a quantity defined as i 0 = i q 2 + i d 2 ; i ref is a quantity defined as i ref = i q , ref 2 + i d , ref 2 ; t 0 is a predetermined initial instant; tf is a predetermined final instant subsequent to the predetermined initial instant, for example a current instant; v lim is a limit voltage defined as v lim = αv DC; α being the modulation index of the inverter 10. The modulation index α preferably has a value between 1 / √3 and 1.

[0058] The quantity i 0 defined above is the norm of a vector (noted i 0 ) equal to the vector sum, in the rotating frame, of the measured direct current id and the measured quadrature current iq .

[0059] Furthermore, the quantity i ref defined above is the norm of a vector (denoted i ref) equal to the vector sum, in the rotating frame, of the direct current setpoint id,ref and the quadrature current setpoint iq,ref.

[0060] Advantageously, the coefficients K' p,q and K' i,q are chosen so that the value of the quadrature voltage setpoint vq,ref calculated using relation (3) is limited, in particular less than or equal to the limit voltage v lim .

[0061] Preferably, the predetermined condition is verified when a first situation occurs in the quantity v q , ref 2 + v d , ref 2 becomes greater than or equal to a predetermined fraction of the quantity v lim 2 , advantageously greater than or equal to 0 , 75 . v lim 2 , for example greater than or equal to 0 , 9 . v lim 2 , or even equal to v lim 2 .

[0062] For example, the predetermined condition is thus verified when, while the current control member 22 calculates the direct voltage setpoint vd,ref and the quadrature voltage setpoint vq,ref according to the second calculation mode, the quantity v q , ref 2 + v d , ref 2 becomes greater than or equal to a predetermined fraction of the quantity v lim 2 , advantageously greater than or equal to 0 , 75 . v lim 2 , for example greater than or equal to 0 , 9 . v lim 2 , or even equal to v lim 2 .

[0063] Furthermore, if the predetermined condition is not met, the current control member 22 is configured to calculate the direct voltage setpoint vd,ref and the quadrature voltage setpoint vq,ref, according to the second calculation mode, preferably by implementing two “proportional-integral” type correctors. In this case, the current control member 22 is configured to calculate the direct voltage setpoint vd,ref and the quadrature voltage setpoint vq,ref by implementing the following relationships (3): v q , ref = K p , q i q , ref − i q + K i , q ∫ t 0 t f i q , ref − i q dt v d , ref = K p , d i d , ref − i d + K i , d ∫ t f t i d , ref − i d dt where K p,q and K i,q are two predetermined coefficients of the proportional-integral corrector associated, in the second calculation mode, with the quadrature voltage setpoint, not necessarily equal to the coefficients K' p,q and K' i,q mentioned previously; K p,d and K i,d are two predetermined coefficients of the proportional-integral corrector associated, in the second calculation mode, with the direct voltage setpoint; t 0 is a predetermined initial instant; and tf is a predetermined final instant subsequent to the predetermined initial instant, for example a current instant.

[0064] It follows from the above that the first calculation mode corresponds to a situation where defluxing of the machine is required (and is implemented). Relation (5) ensures that the rotating machine 4 operates at maximum power. Furthermore, relation (4) leads to the calculation of a voltage setpoint which will result in an injection of current into the stator windings leading to defluxing of the rotating machine.

[0065] Since the quadrature component of the power consumed by the rotating machine 4 is predominant over the direct component, it is advantageous that relation (4) is implemented on the quadrature voltage vq,ref , so that the action of the proportional-integral regulator is optimal. Another reason why it is advantageous that relation (4) is implemented on the quadrature voltage and not on the direct voltage is that the value of the quadrature voltage is likely to change sign during the operation of the rotating machine 4, so that there is no bijection between the direct voltage and the vector i 0 .

[0066] The implementation of a single proportional-integral regulator ensures more robust control of the rotating machine 4, which results in greater stability of the mechanical torque provided by the rotating machine 4.

[0067] The first transformation member 24 is configured to calculate a first, a second and a third phase voltage setpoint, respectively v A,ref , v B,ref , v C,ref . Each of the phase voltage setpoints v A,ref , v B,ref , v C,ref corresponds to a target voltage for the corresponding phase v A , v B , v C of the stator of the rotating machine 4.

[0068] More precisely, the first transformation member 24 is configured to calculate the phase voltage setpoints v A,ref , v B,ref , v C,ref from the direct voltage setpoint vd,ref and the quadrature voltage setpoint vq,ref calculated by the current control member 22.

[0069] Preferably, the first transformation member 24 is configured to calculate the phase voltage setpoints v A,ref , v B,ref , v C,ref by applying an inverse Park transformation to the direct voltage setpoint vd,ref and the quadrature voltage setpoint vq,rer . Such a transformation is implemented by applying the following relation (6): V A , ref V B , ref V C , ref = cos θ e − sin θ e cos θ e − 2 π 3 − sin θ e − 2 π 3 cos θ e + 2 π 3 − sin θ e + 2 π 3 V d , ref V q , ref where, as previously described, θ e is the electrical angular position of the rotor relative to the stator of the rotating machine 4.

[0070] The pulse width modulation member 28 is configured to generate the switching control signal to be applied to the inverter 10. More precisely, the pulse width modulation member 28 is configured to determine the switching control signal intended to control the inverter 10 so that the voltages v A , v B , v C applied by the inverter 10 to the corresponding phases A, B, C of the rotating machine 4 are, ideally, equal to the first, second and third phase voltage setpoints v A,ref , v B,ref , v C,ref respectively.

[0071] The determination of a switching control signal from any phase voltage setpoints is known per se.

[0072] The operation of the control system 6 will now be described.

[0073] The control system receives a value of a desired target torque T ref at the output of the rotating machine 4.

[0074] Over time, the angular position sensor 12 measures the angular position θ of the rotor of the rotating machine 4 relative to the stator, and delivers the angular position signal.

[0075] Furthermore, over time, the current sensor 14 measures the intensity i A , i B , i C of the current supplying each corresponding phase of the stator of the rotating machine 4, and delivers the intensity signal.

[0076] Furthermore, over time, the voltage sensor 16 measures the voltage v DC , and delivers the voltage signal.

[0077] Then, from the target torque T ref , the angular speed signal and the voltage signal, the current setpoint calculation unit 20 calculates the direct current setpoint id,ref and the quadrature current setpoint iq,ref .

[0078] Furthermore, from the intensity signal, the second transformation member 26 calculates the measured direct current id and the measured quadrature current iq.

[0079] Then, from the direct current setpoint id,ref , the quadrature current setpoint iq,ref , the measured direct current id and the measured quadrature current iq , the current control member 22 calculates the direct voltage setpoint vd,ref and the quadrature voltage setpoint vq,ref .

[0080] More precisely, if the predetermined condition is met, the current control member 22 calculates the direct voltage setpoint vd,ref and the quadrature voltage setpoint vq,ref according to the first calculation mode, which implements a single proportional-integral regulator.

[0081] If the predetermined condition is not met, the current control member 22 calculates the direct voltage setpoint vd,ref and the quadrature voltage setpoint vq,ref according to the second calculation mode, which implements, for example, two “proportional-integral” type regulators.

[0082] Then, the first transformation member 24 calculates the first, second and third phase voltage setpoint v A,ref , v B,ref , v C,ref .

[0083] Then, the pulse width modulation member 28 generates the switching control signal in order to control the inverter 10 so that the voltages v A , v B , v C applied by the inverter 10 to the corresponding phases A, B, C of the rotating machine 4 are equal to the first, second and third phase voltage setpoints v A,ref , v B,ref , v C,ref respectively.

[0084] According to a variant of the invention, the second transformation member 26 is configured to first apply a Clarke transformation to the intensities i A , i B , i C , then a Park transformation to the result obtained, in order to obtain the measured direct current id and the measured quadrature current iq . The Clarke transformation is known per se.

[0085] According to another variant, the limit voltage v lim represents only a fraction of the quantity α.v DC , advantageously at least 0.5.α.v DC , preferably at least 0.75.α.v DC , for example at least 0.9.α.v DC .

[0086] According to another variant, the predetermined condition is verified when a second situation occurs in which an angular speed ω of the rotor, equal to the derivative with respect to time of the angular position θ of the rotor, is greater than or equal to a predetermined base speed ω b.

[0087] According to another variant, the predetermined condition is verified when either of the first situation or the second situation previously described occurs.

[0088] According to another variant, the current control member 22 is configured to calculate the direct voltage setpoint vd,ref and the quadrature voltage setpoint vq,ref according to the first calculation mode only, at all times and without verifying the fulfillment of any condition.

[0089] According to another variant, the computer 18 is configured to control the operation of the inverter 10 as a function, not of the target torque T ref , but of a target rotation speed ω ref of the rotor of the rotating machine 4. In this case, the computer 18 further comprises a conversion member (not shown) configured to convert the target rotation speed ω ref into the target torque T ref to be supplied to the target current calculation member 20. In particular, the conversion member is configured to convert the target rotation speed ω ref into the target torque T ref from the angular speed signal from the angular speed sensor 12, by implementing the following relationship (7): T ref = G p ω ref − ω + G i ∫ t 0 t f ω ref − ω dt where G p and G i are two predetermined coefficients; t 0 is a predetermined initial instant; and tf is a predetermined final instant subsequent to the predetermined initial instant, for example a current instant.

[0090] The method and system according to the invention are particularly advantageous. Indeed, by using a single proportional-integral regulator, the method according to the invention reduces the coupling of direct and quadrature quantities with each other, which results in less non-linearities in the control, and therefore allows control of the rotating machine in which the maximum available voltage is applied to the terminals of the rotating machine, without any problems of lack of stability arising. Such a method is therefore capable of increasing the efficiency of the rotating machine during defluxing.

[0091] Furthermore, the method and system according to the invention use linear relationships for implementing the control: the control takes into account a difference between the current i 0 consumed by the rotating machine 4 and the current setpoint i ref to determine the quadrature voltage setpoint vq,ref , according to a linear relationship (and this, without prior constraint on the value of the quadrature voltage setpoint vq,ref ). This results in increased stability compared to conventional control methods. For example, this results in increased stability compared to certain conventional control methods in which, for example, the controlled quantity is an angle, in the rotating frame of reference, of the voltage across the terminals of the rotating machine 4.Since the relationship between such an angle and the current consumed by the rotating machine 4 is not linear, such a conventional method offers less satisfactory performance than the method according to the invention, particularly in terms of stability.

[0092] The method and system according to the invention also allow monitoring of the angle formed between the respective directions of the magnetic flux of the rotor magnets and the currents, in the rotating frame linked to the rotor. In this way, it is possible to control the inverter so as to maintain the value of said angle below a predetermined angle, for example to prevent the machine from switching from a so-called "motor" operation, in which the rotating machine absorbs energy and delivers mechanical torque, to a so-called "generator" operation, in which the rotating machine converts mechanical energy to the rotor into electrical energy.

Claims

1. Method for controlling a permanent-magnet synchro-reluctant or synchronous three-phase rotating machine (4), comprising the following steps: - measuring a current (iA, iB, iC) flowing in each of the phases of a stator of the rotating machine (4); - carrying out a first calculation, by way of a single proportional-integral controller, of a switching control signal for controlling an inverter (10), as a function of each measured current (iA, iB, iC) and a target value (Tref) for a mechanical torque supplied by the rotating machine (4) or a target value for an angular velocity of a rotor of the rotating machine (4) with respect to the stator, the inverter (10) being configured to convey electrical energy between a DC electrical energy source (8) and each phase of the stator of the rotating machine (4), characterized in that the first calculation comprises determining a quadrature voltage setpoint (vq,ref) according to: v q , ref = K ′ p , q i 0 − i ref + K ′ i , q ∫ t 0 t f i 0 − i ref dt where vq,ref is the quadrature voltage setpoint; K'p,q and K'i,q are predetermined coefficients of the single proportional-integral corrector; i0 is a quantity defined as i 0 = i q 2 + i d 2 ; iref is a quantity defined as i ref = i q , ref 2 + i d , ref 2 ; t0 is a predetermined initial time; tf is a predetermined final time subsequent to the predetermined initial time; id and iq are respectively a measured direct current and a measured quadrature current, dependent on each measured current; id,ref and iq,ref are respectively a direct current setpoint and a quadrature current setpoint, each representative of the target value (Tref) for the mechanical torque supplied by the rotating machine or of the target value (ωref) for the angular velocity of the rotor of the rotating machine (4) with respect to the stator, the first calculation furthermore comprising determining a direct voltage setpoint (vd,ref) according to: v d , ref = v lim 2 − v q , ref 2 where vd,ref is the direct voltage setpoint; vlim is a limit voltage defined as vlim = αvDC; α being a predetermined modulation index of the inverter (10); the switching control signal being a function of the quadrature voltage setpoint (vq,ref) and of the direct voltage setpoint (vd,ref); - controlling the inverter (10) by way of the calculated switching control signal.

2. Control method according to Claim 1, wherein the modulation index has a value between 1 / √3 and 1.

3. Control method according to either one of Claims 1 and 2, wherein the predetermined coefficients of the single proportional-integral corrector are chosen so that the value of the determined quadrature voltage setpoint (vq,ref) is limited, preferably less than or equal to a limit voltage defined as: vlim = αvDC where vlim is the limit voltage; α is a predetermined modulation index of the inverter (10); and vDC is a voltage between the source (8) and a potential reference.

4. Control method according to any one of Claims 1 to 3, wherein the first calculation is implemented if a predetermined condition is satisfied.

5. Control method according to Claim 4, comprising determining a direct voltage setpoint (vd,ref) and a quadrature voltage setpoint (vq,ref) that are dependent on each measured current (iA, iB, iC), the predetermined condition being satisfied if the sum of the squares of the direct voltage setpoint (vd,ref) and of the quadrature voltage setpoint (vq,ref) is greater than or equal to a predetermined fraction of the square of a predetermined limit voltage, advantageously greater than or equal to 75% of the square of the predetermined limit voltage, for example greater than or equal to 90% of the square of the predetermined limit voltage, or else equal to the square of the predetermined limit voltage.

6. Control method according to Claim 5, wherein the direct voltage setpoint (vd,ref) and the quadrature voltage setpoint (vq,ref) are determined when carrying out a second calculation of the switching control signal, separate from the first calculation, the predetermined condition being satisfied if, during the implementation of the second calculation, the sum of the squares of the direct voltage setpoint (vd,ref) and of the quadrature voltage setpoint (vq,ref) becomes greater than or equal to the predetermined fraction of the square of a predetermined limit voltage, or else equal to the square of the predetermined limit voltage.

7. Control method according to any one of Claims 4 to 6, wherein the predetermined condition is satisfied if the angular velocity of the rotor of the rotating machine (4) with respect to the stator is greater than or equal to a predetermined base speed.

8. Control system (6) for a permanent-magnet synchro-reluctant or synchronous three-phase rotating machine (4), comprising: - a current sensor (14) configured to measure a current (iA, iB, iC) flowing in each of the phases of a stator of the rotating machine (4); - an inverter (10) configured to convey electrical energy between a DC electrical energy source (8) and each phase of the stator of the rotating machine (4); and - a computer (18) configured to carry out, by implementing a single proportional-integral controller, a first calculation of a switching control signal for controlling the inverter (10), as a function of each current (iA, iB, iC) measured by the current sensor (14) and a quantity representative of a target value (Tref) for a mechanical torque supplied by the rotating machine or a target value for an angular velocity of a rotor of the rotating machine with respect to the stator, characterized in that the first calculation comprises determining a quadrature voltage setpoint (vq,ref) according to: v q , ref = K ′ p , q i 0 − i ref + K ′ i , q ∫ t 0 t f i 0 − i ref dt where vq,ref is the quadrature voltage setpoint; K'p,q and K'i,q are predetermined coefficients of the single proportional-integral corrector; i0 is a quantity defined as i 0 = i q 2 + i d 2 ; iref is a quantity defined as i ref = i q , ref 2 + i d , ref 2 ; t0 is a predetermined initial time; tf is a predetermined final time subsequent to the predetermined initial time; id and iq are respectively a measured direct current and a measured quadrature current, dependent on each measured current; id,ref and iq,ref are respectively a direct current setpoint and a quadrature current setpoint, each representative of the target value (Tref) for the mechanical torque supplied by the rotating machine or of the target value (ωref) for the angular velocity of the rotor of the rotating machine (4) with respect to the stator; the first calculation furthermore comprising determining a direct voltage setpoint (vd,ref) according to: v d , ref = v lim 2 − v q , ref 2 where vd,ref is the direct voltage setpoint; vlim is a limit voltage defined as vlim = αvDC; α being a predetermined modulation index of the inverter (10), the computer (18) furthermore being configured to apply the calculated switching control signal to the inverter (10) in order to control the inverter (10).

9. Control system (6) according to Claim 8, wherein the computer (18) is configured to implement the control method according to any one of Claims 1 to 7, except for the measuring step.