METHOD FOR CONTROLLING A RECTIFIER CONNECTED TO A PERMANENT MAGNETIC SYNCHRON GENERATOR TO PROVIDE A DC VOLTAGE, ACCORDING DEVICE AND COMPUTER PROGRAM

Description

[0001] The present invention relates to a method for controlling a rectifier connected to a permanent magnet synchronous electric generator to provide a direct voltage, and to a corresponding computer program and device.

[0002] The state of the art includes in particular documents WO-A2-2014 / 173954, US-A1-2013 / 106368 and US-A1-2013 / 335041.

[0003] To control an inverter connected between an electric motor and a direct voltage source, it is known to use an inverter control method, comprising: determining a first setpoint of a first vector component of the phase currents along a first axis of a rotating reference frame linked to a rotor of the electrical machine, and a second setpoint of a second vector component of the phase currents along a second axis of the rotating reference frame, this second vector component of the phase currents being intended to cause defluxing of the rotor; and controlling the inverter from the first and second setpoints of the vector components of the phase currents.

[0004] This known method uses a measurement of the direct voltage, a torque setpoint of the electric motor and a measurement of the instantaneous rotation speed of the rotor to determine phase current setpoints in a dq reference frame attached to the rotor. More precisely, tables are provided giving respectively the direct current setpoint and the quadrature current setpoint from the measurement of the direct voltage, the torque setpoint and the measurement of the instantaneous rotation speed.

[0005] Furthermore, for electrical machines operating as generators, it is known to use a method for controlling a rectifier connected to phases of the permanent magnet synchronous electric generator to provide a direct voltage, the phases being designed to be traversed by phase currents during a drive of the electric generator, the method comprising: determining a first setpoint of a first vector component of the phase currents along a first axis of a rotating reference frame linked to a rotor of the electric generator, and a second setpoint of a second vector component of the phase currents along a second axis of the rotating reference frame, this second vector component of the phase currents being intended to cause defluxing of the rotor; and controlling the rectifier from the first and second setpoints of the vector components of the phase currents.

[0006] It may thus be desirable to provide a control method adapted to an electrical machine operating as a generator and in particular a multi-star and multi-phase machine, that is to say a machine which comprises several stars and for which each star is at least three-phase.

[0007] A method is therefore proposed for controlling a rectifier connected to phases of the permanent magnet synchronous electric generator to provide a direct voltage, the phases being designed to be traversed by phase currents during a drive of the electric generator, the method comprising: determining a first setpoint of a first vector component of the phase currents along a first axis of a rotating reference frame linked to a rotor of the electric generator, and a second setpoint of a second vector component of the phase currents along a second axis of the rotating reference frame, this second vector component of the phase currents being intended to cause defluxing of the rotor; and controlling the rectifier from the first and second setpoints of the vector components of the phase currents; the first setpoint of the first vector component of the phase currents being determined from an external regulation loop designed to control a voltage of a DC bus or to regulate a current of a battery connected to the DC bus, said method being characterized in that it further comprises: determining a first theoretical setpoint of the first vector component of the phase currents; determining a second theoretical setpoint of the second vector component of the phase currents; and if an amplitude of a vector sum of the setpoints of the vector components of the phase currents is less than or equal to a predefined threshold, providing the theoretical setpoints as setpoints of the vector components of the phase currents;and otherwise, limiting the first theoretical setpoint and / or the second theoretical setpoint so that an amplitude of a vector sum of the theoretical setpoints is less than or equal to the predefined threshold, and providing the theoretical setpoints after limitation as setpoints of the vector components of the phase currents. ;

[0008] Thus, thanks to the invention, the first setpoint is determined from the external control loop, so that it is not necessary to know the operating characteristics of the electric machine. In particular, there is no need to use a torque setpoint of the electric machine or a measurement of the instantaneous rotational speed of the rotor, as is necessary in the known method adapted to the electric motor.

[0009] Optionally, the rectifier control from the first and second instructions includes: determining phase voltage setpoints of the electric generator; and controlling the rectifier from the phase voltage setpoints; and the second setpoint of the second vector component of the phase currents is determined from the phase voltage setpoints.

[0010] Optionally also, the second setpoint of the second vector component of the phase currents is taken equal to a predefined constant.

[0011] Optionally also, the second setpoint of the second vector component of the phase currents is determined from the first setpoint of the first vector component of the phase currents.

[0012] Also optionally, the second setpoint of the second vector component of the phase currents is determined by means of a table associating values ​​of the second setpoint of the second vector component of the phase currents with values ​​of the first setpoint of the first vector component of the phase currents.

[0013] Optionally also, the second setpoint of the second vector component of the phase currents is determined by means of a function associating values ​​of the second setpoint of the second vector component of the phase currents with values ​​of the first setpoint of the first vector component of the phase currents.

[0014] There is also provided a computer program downloadable from a communication network and / or recorded on a computer-readable medium, characterized in that it comprises instructions for executing the steps of a control method according to the invention, when said program is executed on a computer.

[0015] There is also provided a device for controlling a rectifier connected to phases of a permanent magnet synchronous electric generator to provide a direct voltage, the phases being designed to be traversed by phase currents during a drive of the electric generator, the control device comprising: a module designed to determine a first setpoint of a first vector component of the phase currents along a first axis of a rotating reference frame linked to a rotor of the electric generator, and a second setpoint of a second vector component of the phase currents along a second axis of the rotating reference frame, this second vector component of the phase currents being intended to cause defluxing of the rotor; and a module for controlling the rectifier from the first and second setpoints of the vector components of the phase currents; characterized in that the first setpoint of the first vector component of the phase currents is determined from an external control loop designed to control a voltage of a DC bus or to regulate a current of a battery connected to the DC bus, and in that the module is further designed to: determine a first theoretical setpoint of the first vector component of the phase currents; determine a second theoretical setpoint of the second vector component of the phase currents; and if an amplitude of a vector sum of the setpoints of the vector components of the phase currents is less than or equal to a predefined threshold, provide theoretical setpoints as setpoints of the vector components of the phase currents;and otherwise, limiting the first theoretical setpoint and / or the second theoretical setpoint so that an amplitude of a vector sum of the theoretical setpoints is less than or equal to the predefined threshold, and providing theoretical setpoints after limitation as setpoints of the vector components of the phase currents. ;

[0016] The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which: [ Fig. 1 ] there figure 1 is a schematic representation of an electrical installation according to a non-limiting example of implementation of the invention, comprising a rectifier connected to an electric generator, as well as a device for controlling the rectifier, [ Fig. 2 ] there figure 2 is a schematic representation of modules of the control device of the figure 1 , according to a first example of embodiment, [ Fig. 3 ] there figure 3 is a block diagram illustrating steps of a method for controlling the rectifier of the electrical installation of the figure 1 with the control device of the figure 2 , [ Fig. 4 ] there figure 4 is a schematic representation of modules of the control device of the figure 1 , according to a second exemplary embodiment, [ Fig. 5 ] there figure 5 is a block diagram illustrating steps of a method for controlling the rectifier of the electrical installation of the figure 1 with the control device of the figure 4 , [ Fig. 6 ] there figure 6 is a schematic representation of modules of the control device of the figure 1 , according to a third embodiment, [ Fig. 7 ] there figure 7 is a block diagram illustrating steps of a method for controlling the rectifier of the electrical installation of the figure 1 with the control device of the figure 6 , [ Fig. 8 ] there figure 8 is a schematic representation of modules of the control device of the figure 1 , according to a fourth embodiment, and [ Fig. 9 ] there figure 9 is a block diagram illustrating steps of a method for controlling the rectifier of the electrical installation of the figure 1 with the control device of the figure 8 .

[0017] In reference to the figure 1 , a non-limiting example of an electrical installation 100 implementing the invention will now be described.

[0018] The electrical installation 100 is for example designed to be part of an aircraft, in particular a vertical take-off and landing (VTOL) aircraft.

[0019] The electrical installation 100 comprises an electrical power supply system 102 and a load 104 supplied by the electrical power supply system 102. For example, the load 104 comprises various equipment of the aircraft.

[0020] The electrical power system 102 comprises an electrical generation chain 106 comprising first of all a permanent magnet synchronous electrical machine 108, designed to operate as a generator. The electrical generator 108 comprises a stator 110 and a rotor 112 designed to be driven in rotation relative to the stator 110, around an axis of rotation Δ. The rotor 112 comprises one or more permanent magnets (not shown) designed to generate a rotor magnetic field along an axis d, called the direct axis, attached to the rotor 112. The electrical generator 108 further has an input shaft 114 secured to the rotor 112. To drive the rotor 112 in rotation, the electrical generation chain 106 further comprises, in the example described, a gas turbine 116 connected to the input shaft 114.

[0021] In the example described, the electric generator 108 is multi-star (in this case two stars) and each star is three-phase in star with a single neutral. For the sake of clarity, only one star is shown on the figure 1 . Those skilled in the art will appreciate that the invention applies, in general, to a multi-star permanent magnet synchronous electric machine (i.e., the number of stars is greater than or equal to 1) and multi-phase (i.e., the number of phases per star is greater than or equal to 3). The stator 110 comprises three phases A, B, C whose magnetic axes are oriented respectively in three directions a, b, c transverse to the axis of rotation Δ of the rotor 112 and intersecting on this axis of rotation Δ. The electric generator 108 is preferably balanced so that the three directions a, b, c are separated from each other by an angle of 120°. The three phases A, B, C have respective first ends connected together to the same neutral point N.

[0022] During rotation of the rotor 112, the phases A, B, C are designed to be respectively traversed by phase currents Ia, Ib, Ic respectively generating magnetic fields in the three directions a, b, c.

[0023] Furthermore, during operation of the electric generator 108, the phases A, B, C have respective phase voltages relative to the neutral point N, denoted Va, Vb, Vc.

[0024] As will be described in more detail later, the electric generator 108 is designed to be vector-controlled. Thus, each phase current 1a, 1b, 1c is associated with a phase current vector having an amplitude equal to the phase current 1a, 1b, 1c and extending in the direction a, b, c of the phase A, B, C traversed by this phase current 1a, 1b, 1c. The phase currents 1a, 1b, 1c are thus expressed in a reference frame formed by the axes a, b, c, called the abc reference frame. The phase currents 1a, 1b, 1c are therefore globally represented by a global phase current vector equal to the vector sum of the phase current vectors.

[0025] To simplify the control by using substantially continuous quantities rather than directly the alternating phase currents 1a, 1b, 1c, the overall phase current vector is expressed in a rotating reference frame R attached to the rotor 112 and comprising the direct axis d and a quadrature axis q, perpendicular to the direct axis d in the case where the rotor 112 has a single pair of north-south poles. In general, the invention applies to a rotor having a number of pole pairs greater than or equal to one. Thus, the overall phase current vector is expressed by two components: a direct component Id along the direct axis d and a quadrature component Iq along the quadrature axis q. In this way, the phase currents 1a, 1b, 1c are represented by the components Id, Iq. To convert from the phase currents 1a, 1b, 1c to the components Id, Iq, the Park transform or the dqo transform can be used.The transition from the components Id, Iq to the phase currents Ia, Ib, Ic is done for example by means of inverse transforms.

[0026] Similarly, the phase voltages Va, Vb, Vc in the abc frame are represented by direct components Vd and quadrature components Vq in the rotating frame R.

[0027] In order to convert the phase voltages Va, Vb, Vc into a voltage that can be applied to the load 104, the electrical generation chain 106 further comprises a rectifier 118 designed to convert the alternating phase voltages Va, Vb, Vc into a direct voltage Vdc. The rectifier 118 comprises, for each phase voltage Va, Vb, Vc, a respective switching arm comprising a high-side switch and a low-side switch connected to each other at a midpoint to which the phase voltage Va, Vb, Vc in question is applied and receiving the phase current Ia, Ib, Ic of this phase A, B, C.

[0028] The electrical generation chain 106 further comprises a bus 120 comprising two supply lines (respectively positive and negative) between which the switching arms of the rectifier 118 are connected and distributing the direct voltage Vdc to the various equipment forming the load 104. The bus 120 is generally called an HVDC bus (from the English “High Voltage Direct Current”) and the direct voltage Vdc that it transports is generally a high voltage, that is to say for example equal to 540 V (standard voltage in aeronautics), or even greater than 540 V. To smooth the direct voltage Vdc, the rectifier 118 preferably comprises a capacitor Cp between the supply lines of the bus 120.

[0029] In the example described, the electrical generation chain 106 further comprises a battery 122 connected to the bus 120 to participate in the generation of the direct voltage Vdc. The battery 122 has a state of charge varying over time and therefore influencing the direct voltage Vdc of the bus 120.

[0030] The rectifier 118 is sometimes called an active rectifier since it is designed to be controlled, so that the direct voltage Vdc on the bus 120 can be maintained close to a setpoint Vdc_ref despite variations in the charge of the battery 122 and the phase voltages Va, Vb, Vc. This setpoint Vcd_ref can be varied over time, depending on the needs of the equipment forming the load 104.

[0031] Furthermore, the rectifier 118 can also be used to maintain a current Ibat in the battery 122 substantially equal to a current setpoint Ibat_ref regardless of the variations in the voltage Vdc and the phase voltages Va, Vb, Vc.

[0032] Thus, in order to control the rectifier 118, the electrical generation chain 106 further comprises a measuring device 121 designed to provide a measurement Vdc_mes of the direct voltage Vdc, a measuring device 123 designed to provide measurements la_mes, Ib_mes, Ic_mes of the phase currents la, Ib, Ic and a measuring device 127 designed to provide a measurement ST of a state of the electrical generator 108.

[0033] In particular, the measuring device 127 may be, for example, a position sensor, such as a resolver, which directly measures the angular position information of the rotor 112 or a synchronous generator mounted on the shaft of the electric generator 106 and rotating at no load. In this case, the angular position of the rotor 112 is deduced from measurements of the no-load electromotive forces of the latter.

[0034] Furthermore, the power supply system 102 comprises a control device 124 of the rectifier 118 designed more precisely to provide respective switching commands CMD to the switches of the rectifier 118, in order to connect each phase A, B, C alternately to the positive line and to the negative line of the bus 120.

[0035] The control device 124 firstly comprises a module 126 designed to determine a setpoint Id_ref of the direct component Id of the phase currents Ia, Ib, Ic and a setpoint Iq_ref of the quadrature component Iq of the phase currents Ia, Ib, Ic.

[0036] Different possible realizations of module 126 will be described later with reference to the figures 2 , 4 , 6 And 8 .

[0037] The control device 124 further comprises a module 128 for controlling the rectifier 118 from the instructions Iq_ref, ld_ref.

[0038] The module 128 comprises a module 130 designed to determine an angular position θ of the rotor 112 from the measurement ST of the state of the electric generator 108.

[0039] The module 128 further comprises a module 132 designed to convert, from the angular position θ of the rotor 112, the measurements la_mes, Ib_mes, Ic_mes into measurements Id_mes, Iq_mes in the rotating frame R. The module 132 uses for example the Park transform, the dqo transform or even the Fortescue transform generalized to a given number of phases.

[0040] The module 128 further comprises a module 134 designed to determine setpoints Vd_ref, Vq_ref of the direct and quadrature components Vd, Vq of the phase voltages Va, Vb, Vc, from the setpoints Id_ref, Iq_ref and the measurements Id_mes, Iq_mes. The setpoints Vd_ref, Vq_ref therefore form a vector setpoint of the phase voltages Va, Vb, Vc. The module 134 is for example designed to determine an error from a difference between the setpoints Id_ref, Iq_ref and the measurements Id_mes, Iq_mes and to use correctors, for example proportional-integral correctors, to determine the setpoints Vd_ref, Vq_ref from the error.

[0041] The module 128 further comprises a module 136 designed to convert, from the angular position θ, the setpoints Vd_ref, Vq_ref into setpoints Va_ref, Vb_ref, Vc_ref in the abc frame. The module 136 uses, for example, the inverse Park transform, the inverse dqo transform or the Fortescue transform generalized to a given number of phases.

[0042] The module 128 further comprises a module 138 designed to determine the switching commands CMD of the switches of the rectifier 118 from the instructions Va_ref, Vb_ref, Vc_ref.

[0043] In the described example, the control device 124 comprises a computer system comprising a processing unit 140 (such as a microprocessor) and a memory 142 (such as a main memory) in which a computer program is recorded containing computer program instructions designed to be executed by the processing unit 140. Thus, the modules described above are implemented in the described example in the computer program in the form of software modules.

[0044] Alternatively, all or part of the modules could be implemented as hardware modules, i.e. in the form of an electronic circuit, for example micro-wired, not involving a computer program.

[0045] In reference to the figure 2 ,A first example of embodiment of the module 126 will now be described in more detail. The module 126 firstly comprises a module 201 designed to determine a theoretical setpoint Iq_ref* of the quadrature component Iq of the phase currents Ia, Ib, Ic, from the measurement Vdc_mes and the setpoint Vdc_ref. For example, the theoretical setpoint Iq_ref* is determined by the equation: Iq _ ref * = V dc _ ref 2 − V dc _ mes 2 × Kp + Ki s where s is the Laplace operator, Kp a gain of the proportional action and Ki a gain of the integral action.

[0046] The module 126 further comprises a module 202 designed to determine an amplitude V_ref of the vector setpoint of the phase voltages. In the example described where the vector setpoint of the phase voltages is expressed in the rotating frame R by the components Vd_ref, Vq_ref, the module 202 is for example designed to determine the amplitude V_ref according to the following equation: V _ ref = Vd _ ref 2 + Vq _ ref 2

[0047] The module 126 further comprises a module 204 designed to determine a difference D between the amplitude V_ref and a threshold V_max corresponding to a maximum voltage admissible by the electric generator 108 defined for a given measured DC voltage Vdc_mes and a given modulation strategy used by the module 138. The module 204 is for example designed to determine the difference D according to the following equation: D = V _ max − V _ ref

[0048] The module 126 further comprises a module 206 designed to receive the difference D and determine, from this difference D, a theoretical setpoint Id_ref* of the direct component Id of the phase currents Ia, Ib, Ic.

[0049] More precisely, if this difference D is negative, that is to say if the amplitude V_ref is greater than the threshold V_max, then the electric generator 108 must be controlled in defluxing mode and the module 206 is then designed to provide a non-zero theoretical setpoint Id_ref* intended to cause defluxing of the rotor 112, that is to say to cause the generation of a defluxing magnetic field along the direct axis d opposing the magnetic field produced by the rotor 112 along the direct axis d. In the example described, the electric generator 108 is modeled in motor convention, so that the theoretical setpoint Id_ref* is negative to obtain the defluxing magnetic field. The module 206 uses for example a proportional integrator corrector to determine the theoretical setpoint Id_ref*. In particular, this proportional integrator corrector can be applied to D according to the equation: I _ d ref * = D × Kp + Ki s where s is the Laplace operator, Kp the gain of the proportional action and Ki the gain of the integral action.

[0050] If the amplitude V_ref is less than or equal to the predefined threshold V_max (positive or zero difference D), then the electric generator 108 does not need to be controlled in defluxing mode and the module 206 is then designed so that the theoretical setpoint Id_ref* is positive or zero.

[0051] The module 126 further comprises a module 207 designed to determine the instructions Iq_ref, Id_ref by limiting if necessary the theoretical instruction Iq_ref* and / or the theoretical instruction Id_ref*.

[0052] More specifically, module 207 is first designed to limit the theoretical setpoint Id_ref* so that it does not risk causing the generation of a magnetic field along the direct axis d in addition to the magnetic field produced by the rotor 112 along the direct axis d. With the conventions used in the example described, module 207 is designed to prevent the setpoint ld_ref from being positive by limiting the theoretical setpoint Id_ref* to zero.

[0053] Module 207 is further designed to prevent the Iq_ref setpoint from being positive by limiting the theoretical Iq_ref* setpoint to zero. Indeed, according to the adopted convention, the operation in generator mode of the electric machine requires a negative Iq current.

[0054] The module 207 is further designed to limit the theoretical setpoint Iq_ref* and / or the theoretical setpoint Id_ref* so that the amplitude of their vector sum after limitation remains less than or equal to a threshold I_max. This threshold I_max corresponds, for example, to a maximum current supported by the power electronics, in particular the switches of the rectifier 118.

[0055] Module 207 is then designed to provide the theoretical instructions Iq_ref*, Id_ref* after limitation as instructions lq_ref, ld_ref.

[0056] In the example described, to achieve these different limitations of the theoretical setpoints Iq_ref*, Id_ref*, the module 207 firstly comprises a module 208 designed to limit the negative amplitude of the theoretical setpoint Id_ref* to the threshold -I_max and its positive amplitude to zero. Thus, the setpoint Id_ref is equal to the theoretical setpoint Id_ref* except when, on the one hand, the amplitude of the latter falls below the threshold -I_max, in which case the setpoint Id_ref is equal to -I_max, and, on the other hand, the theoretical setpoint Id_ref* is greater than zero, in which case the setpoint Id_ref is equal to zero. In particular, when defluxing is not necessary (difference D greater than or equal to zero), the setpoint Id_ref is zero.

[0057] The module 207 further comprises a module 210 designed to determine a threshold Iq_ref_max for the setpoint Iq_ref, from the setpoint Id_ref and the threshold I_max, for example according to the equation: Iq _ ref _ max = I _ max 2 − Id _ ref 2

[0058] Module 207 further comprises a module 212 designed to limit the negative amplitude of the theoretical setpoint Iq_ref* to the threshold -Iq_ref_max and its positive amplitude to zero.

[0059] In reference to the figure 3 , a first example of a method 300 for controlling the rectifier 118 will now be described. In the example described, the method 300 is implemented by the control device 124, with the module 126 of the figure 2 . Furthermore, those skilled in the art will appreciate that the steps of the described method 300 may be performed in a different order than that shown in the figure 3 and can be executed, for example, concurrently.

[0060] During a step 302, the control device 124 receives the measurements Vdc_mes, Ia_mes, Ib_mes, Ic_mes, ST and Ibat_mes.

[0061] During a step 304, the module 130 determines the rotation angle θ of the rotor 112 from the measurement ST of the state of the electric generator 108.

[0062] During a step 306, the module 132 converts, from the angular position θ of the rotor 112, the measurements la_mes, Ib_mes, Ic_mes into measurements ld_mes, Iq_ref in the rotating frame R.

[0063] During a step 308, the module 126 determines the phase current setpoints Iq_ref, ld_ref.

[0064] For this, during a step 308_2, the module 201 determines the theoretical setpoint Iq_ref* from an external regulation loop for controlling the bus voltage 120 or for regulating the battery current 122, that is to say, for example, from the measurement Vdc_mes and the setpoint Vdc_ref of the direct voltage Vdc or from the measurement Ibat_mes of the battery current and the battery current setpoint Ibat_ref.

[0065] During a step 308_4, the module 202 determines the amplitude V_ref of the vector setpoint of the phase voltages from the setpoints Vq_ref, Vd_ref.

[0066] During a step 308_6, the module 204 determines the difference D between the amplitude V_ref and the threshold V_max.

[0067] During a step 308_8, the module 206 determines, from the difference D, the theoretical setpoint Id_ref*.

[0068] During a step 308_10, the module 207 limits, if necessary, the theoretical setpoint Id_ref* and / or the setpoint Iq_ref* to provide the setpoints lq_ref, Id_ref. The current value Id necessary to reach a given operating point is therefore limited, which results in lower current amplitudes Ia, Ib and Ic and, consequently, less thermal losses in the power electronics and the electrical machine.

[0069] Advantageously, the setpoints Iq_ref and ld_ref are obtained in step 308 independently of operating parameters of the electric generator 108, in particular independently of a torque and a rotation speed of the rotor 112 and without using a torque setpoint of the rotor 112. Furthermore, in general, the operating parameters of the electric generator 108 can designate electrical parameters, such as for example, an inductance matrix, and mechanical parameters, such as for example, the rotation speed of the rotor 112.

[0070] Furthermore, it will be appreciated that the Id_ref setpoint is obtained by closed-loop regulation (“feedback” in English).

[0071] During a step 310, the module 134 determines the setpoints Vd_ref, Vq_ref from the setpoints Id_ref, Iq_ref and the measurements Id_mes, Iq_mes.

[0072] During a step 312, the module 136 converts the instructions Vd_ref, Vq_ref into instructions Va_ref, Vb_ref, Vc_ref in the reference frame abc.

[0073] During a step 314, the module 138 determines the switching commands CMD and supplies them to the switches of the rectifier 118, so that the direct voltage Vdc approaches the reference voltage Vdc_ref.

[0074] In reference to the figure 4 , a second example of embodiment of module 126 will now be described in more detail.

[0075] This example is similar to that of the figure 2 , except that the module 206 is replaced by a module 402 designed to provide, when the difference D is negative, that is to say when the amplitude V_ref is greater than the threshold V_max, a setpoint Id_ref equal to a predefined constant, noted Id_ref°. This constant Id_ref° is chosen to be lower in absolute value than the threshold I_max. When the difference D is positive or zero, the module 402 is designed to provide the setpoint Id_ref equal to zero. It will be appreciated that the difference D is only used to determine the need to activate or not the defluxing. Its precise value is not used in this embodiment, just its sign. Thus, the module 204 could provide the module 402, instead of the difference D, a binary simply indicating the activation or not of the defluxing.

[0076] Furthermore, with the choice of the constant Id_ref° lower (in absolute value) than the threshold I_max, the module 207 is simplified and no longer includes the module 208. In addition, the module 207 only limits, if necessary, the theoretical setpoint Iq_ref*, and not the setpoint Id_ref which remains constant. Finally, the person skilled in the art will appreciate that, in the case where the current sensors Ia, Ib and Ic are used in receiver convention, the constant Id_ref° is negative.

[0077] In reference to the figure 5 , a second example of a method 500 for controlling the rectifier 118 will now be described. In the example described, the method 500 is implemented by the control device 124, with the module 126 of the figure 4 .

[0078] The method 500 is similar to the method 300, except that step 308_8 is replaced by a step 308_8' during which the module 206 provides the setpoint Id_ref equal to zero or to the constant Id_ref°, depending on the sign of the difference D.

[0079] In reference to the figure 6 , a third example of embodiment of module 126 will now be described in more detail.

[0080] In this third example, the Id_ref setpoint is determined from the Iq_ref setpoint, according to a predictive regulation (“feedforward” in English).

[0081] More precisely, modules 206 and 207 are replaced by a module 602 designed to provide, when the difference D is negative, a setpoint Id_ref determined by means of a table associating setpoint values ​​Id_ref with values ​​of the setpoint Iq_ref, such as the following table: [Table 1] Puissance active P [kW] Iq_ref [A] Id_ref [A] 0 ≤ P ≤ -20 0 ≤ Iqref ≤ -40 -30 -20 < P ≤ -40 -40 < Iqref ≤ -75 -40 -40 < P ≤ -60 -75 < Iqref ≤ -110 -50 -60 < P ≤ -80 -110 < Iqref ≤ -140 -60 -80 < P ≤ -90 -140 < Iqref ≤ -160 -75 -90 < P ≤ -95 -160 < Iqref ≤ -178 -90

[0082] Thus, in the example described, contiguous ranges of values ​​of Iq_ref are respectively associated with values ​​of Id_ref. In this table, the associated Iq_ref, Id_ref setpoints are all chosen so that the amplitude of their vector sum is less than I_max.

[0083] Furthermore, in the particular case of a smooth-pole synchronous machine, the current Iq is directly proportional to the active power P and the variation range of the current reference Iq_ref is thus directly deduced from the variation range of the active power.

[0084] When the difference D is positive or zero, the 602 module is designed to provide the setpoint Id_ref equal to zero. Again, only the sign of the difference D is used by the 602 module.

[0085] In reference to the figure 7 ,a third example of a method 700 for controlling the rectifier 118 will now be described. In the example described, the method 700 is implemented by the control device 124, with the module 126 of the figure 6 .

[0086] The method 700 is similar to the method 500, except that step 308_8' is replaced by a step 308_8" during which the module 602 provides the setpoint Id_ref either equal to zero, or from the setpoint Iq_ref and the association table, depending on the sign of the difference D. Furthermore, step 308_10 is deleted because the limitation of the setpoints lq_ref, Id_ref is provided when establishing the association table.

[0087] In reference to the figure 8 , a fourth example of embodiment of module 126 will now be described in more detail.

[0088] In this fourth example, the Id_ref setpoint is also determined from the lq_ref setpoint, according to a predictive regulation (“feedforward” in English).

[0089] More precisely, the module 602 is replaced by a module 802 designed to provide, when the difference D is negative, a setpoint Id_ref determined by means of a function associating setpoint values ​​Id_ref with values ​​of the setpoint Iq_ref. For example, the function is given by the following equation: Id _ ref = Iq _ max − Δ Iq 2 − Iq _ ref 2 where Iq_max and ΔIq are predefined parameters taking into account in particular I_max, so that the amplitude of the vector sum of the setpoints Iq_ref and Id_ref is less than I_max.

[0090] When the difference D is positive or zero, the 802 module is designed to provide the setpoint Id_ref equal to zero. Again, only the sign of the difference D is used by the 802 module.

[0091] In reference to the figure 9 ,a fourth example of method 900 for controlling the rectifier 118 will now be described. In the example described, the method 900 is implemented by the control device 124, with the module 126 of the figure 8 .

[0092] The method 900 is similar to the method 700, except that step 308_8" is replaced by a step 308_8‴ during which the module 802 provides the setpoint Id_ref either equal to zero, or from the setpoint Iq_ref and the association function, depending on the sign of the difference D.

[0093] It is clear that a method of controlling a rectifier such as those described above is well suited to an electrical machine operating as a generator.

[0094] It will also be noted that the invention is not limited to the embodiments described above. It will indeed appear to those skilled in the art that various modifications can be made to the embodiments described above, in light of the teaching which has just been disclosed to them.

[0095] In particular, in general, the electric generator 108 may have more than three phases, distributed in several stars having respective neutrals disconnected from each other. For example, in an alternative embodiment, the electric generator 108 comprises three stars of three windings (phases) each, with three respective neutrals disconnected from each other. When several stars are present, a rectifier associated with a bus is provided for each star.

[0096] In the detailed presentation of the invention given above, the terms used should not be interpreted as limiting the invention to the embodiments set forth in this description, but should be interpreted to include all equivalents the prediction of which is within the reach of those skilled in the art by applying their general knowledge to the implementation of the teaching just disclosed to them.

Claims

1. A method (300; 500; 700; 900) for controlling a rectifier (118) connected to phases (A, B, C) of a synchronous electric generator (108) with permanent magnets to provide a direct current voltage (Vdc), the phases (A, B, C) being designed to have phase currents (la, Ib, Ic) flowing through them when the electric generator (108) is driven, the method comprising: - determining (308): ∘ a first setpoint (Iq_ref) of a first vector component (Iq) of the phase currents (la, Ib, Ic) along a first axis (q) of a rotating reference frame (R) linked to a rotor (112) of the electric generator (108), and ∘ a second setpoint (Id_ref) of a second vector component (Id) of the phase currents (la, Ib, Ic) along a second axis (d) of the rotating reference frame (R), this second vector component (Id) of the phase currents (la, Ib, Ic) being intended to drive a defluxing of the rotor (112); and - controlling (310, 312, 314) the rectifier (118) from the first and second setpoints (Iq_ref, Id_ref) of the vector components (Iq, Id) of the phase currents (la, Ib, Ic); the first setpoint (Iq_ref) of the first vector component (Iq) of the phase currents (la, Ib, Ic) being determined from an external feedback loop designed to feedback-control a voltage of a direct current bus (120) or to regulate a current from a battery (122) connected to the direct current bus (120), said method (300) being characterised in that it further comprises: - determining (308_2) a first theoretical setpoint (Iq_ref*) of the first vector component (Iq) of the phase currents (la, Ib, Ic); - determining (308_8) a second theoretical setpoint (Id_ref*) of the second vector component (Id) of the phase currents (la, Ib, Ic); and - if a magnitude of a vector sum of the setpoints (Iq_ref, Id_ref) of the vector components (Iq, Id) of the phase currents (la, Ib, Ic) is less than or equal to a predefined threshold (I_max), providing (308_10) the theoretical setpoints (Iq_ref*, Id_ref*) as setpoints (Iq_ref, Id_ref) of the vector components (Iq, Id) of the phase currents (la, Ib, Ic); and - otherwise, limiting the first theoretical setpoint (Iq_ref*) and / or the second theoretical setpoint (Id_ref*) so that a magnitude of a vector sum of the theoretical setpoints (Iq_ref*, Id_ref*) is less than or equal to the predefined threshold (I_max), and providing (308_10) the theoretical setpoints (Iq_ref*, Id_ref*) after limiting the vector components (Iq, Id) of the phase currents (la, Ib, Ic) as setpoints (Iq_ref, Id_ref).

2. The method (300) according to claim 1, wherein the control of the rectifier (118) from the first and second setpoints (Iq_ref, Id_ref) comprises: - determining setpoints (Vq_ref, Vd_ref) of phase voltages (Va, Vb, Vc) of the electric generator (108); and - controlling the rectifier (118) from the setpoints (Vq_ref, Vd_ref) of the phase voltages (Va, Vb, Vc); and wherein the second setpoint (Id_ref) of the second vector component (Id) of the phase currents (la, Ib, Ic) is determined from the setpoints (Vq_ref, Vd_ref) of the phase voltages (Va, Vb, Vc).

3. The method (500) according to claim 1, wherein the second setpoint (Id_ref) of the second vector component (Id) of the phase currents (la, Ib, Ic) is set equal to a predefined constant.

4. The method (700; 900) according to claim 1, wherein the second setpoint (Id_ref) of the second vector component (Id) of the phase currents (la, Ib, Ic) is determined from the first setpoint (Iq_ref) of the first vector component (Iq) of the phase currents (la, Ib, Ic).

5. The method (700) according to claim 4, wherein the second setpoint (Id_ref) of the second vector component (Id) of the phase currents (la, Ib, Ic) is determined by means of a table associating values of the second setpoint (Id_ref) of the second vector component (Id) of the phase currents (la, Ib, Ic) to values of the first setpoint (Iq_ref) of the first vector component (Iq) of the phase currents (la, Ib, Ic), the vector sum of the second setpoint (Id_ref) and the first setpoint (Iq_ref) being below a predefined maximum current threshold.

6. The method (900) according to claim 4, wherein the second setpoint (Id_ref) of the second vector component (Id) of the phase currents (la, Ib, Ic) is determined by means of a function associating values of the second setpoint (Id_ref) of the second vector component (Id) of the phase currents (la, Ib, Ic) to values of the first setpoint (Iq_ref) of the first vector component (Iq) of the phase currents (la, Ib, Ic), the vector sum of the second setpoint (Id_ref) and the first setpoint (Iq_ref) being below a predetermined maximum current threshold.

7. A computer program downloadable from a communication network and / or stored on a computer-readable medium, characterised in that it comprises instructions for executing the steps of a method for controlling a rectifier according to any one of claims 1 to 6, when said program is executed on a computer8. A device (124) for controlling a rectifier (118) connected to phases (A, B, C) of a synchronous electric generator (108) with permanent magnets in order to provide a direct current voltage (Vdc), the phases (A, B, C) being designed to have phase currents (la, Ib, Ic) flowing through them when the electric generator (108) is driven, the control device (124) comprising: - a module (126) designed to determine: ∘ a first setpoint (Iq_ref) of a first vector component (Iq) of the phase currents (la, Ib, Ic) along a first axis (q) of a rotating reference frame (R) linked to a rotor (112) of the electric generator (108), and ∘ a second setpoint (Id_ref) of a second vector component (Id) of the phase currents (la, Ib, Ic) along a second axis (d) of the rotating reference frame (R), this second vector component (Id) of the phase currents (la, Ib, Ic) being intended to drive a defluxing of the rotor (112); and - a module (128) for controlling the rectifier (118) on the basis of the first and second setpoints (Iq_ref, Id_ref) of the vector components (Iq, Id) of the phase currents (la, Ib, Ic); the first setpoint (Iq_ref) of the first vector component (Iq) of the phase currents (la, Ib, Ic) is determined from an external feedback loop designed to feedback-control a voltage of a direct current bus (120) or to regulate a current from a battery (122) connected to the direct current bus (120), said device (124) being characterised in that the module (126) is further designed for: - determining a first theoretical setpoint (Iq_ref*) of the first vector component (Iq) of the phase currents (la, Ib, Ic); - determining a second theoretical setpoint (Id_ref*) of the second vector component (Id) of the phase currents (la, Ib, Ic); and - if a magnitude of a vector sum of the setpoints (Iq_ref, Id_ref) of the vector components (Iq, Id) of the phase currents (la, Ib, Ic) is less than or equal to a predefined threshold (I_max), providing theoretical setpoints (Iq_ref*, Id_ref*) as the setpoints (Iq_ref, Id_ref) of the vector components (Iq, Id) of the phase currents (la, Ib, Ic); and - otherwise, limiting the first theoretical setpoint (Iq_ref*) and / or the second theoretical setpoint (Id_ref*) so that a magnitude of a vector sum of the theoretical setpoints (Iq_ref*, Id_ref*) is less than or equal to the predefined threshold (I_max), and providing theoretical setpoints (Iq_ref*, Id_ref*) after limiting the vector components (Iq, Id) of the phase currents (la, Ib, Ic) as setpoints (Iq_ref, Id_ref).