Power management method and device for an electric machine

Abstract

The invention relates to a control device for an electrical machine (2), the device comprising a power management assembly (90) that comprises a power interface (9) and a power supply system (3), the power supply system (3) comprising a power converter (5), the device comprising an electronic control unit (20) configured to control the power interface (9) so as to regulate a power factor between the power converter (5) and the power interface with respect to a power factor setpoint, such that the power interface (9) supplies at least some of the reactive power consumed by the electric machine (2) so that the power management assembly (90) can exchange an apparent power strictly greater than an initial apparent power with the electric machine (2).

Description

[0001] “Method and device for power management for an electrical machine”

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The present invention relates to the power management of electrical machines, such as electric motors and generators, in particular the power management of variable-speed polyphase electrical machines, and more particularly the power management of variable-speed motorization systems equipped with a polyphase electric motor.

[0004] STATE OF THE ART

[0005] The major current challenges for these motorization systems, mainly linked to the issues of decarbonization and sobriety, are:

[0006] - improving energy efficiency;

[0007] - reduction of sizes and masses (mainly for on-board applications);

[0008] - reducing the consumption of materials (especially so-called critical materials such as rare earths).

[0009] All these objectives rely on a major criterion: the power density of the drive systems, i.e. increasing the power supplied by a given drive train. A drive train includes an electric machine and a system for powering the machine. Increasing this density allows us to overcome all the constraints listed above, as it allows us to make smaller engines while maintaining the same performance for the drive train.

[0010] This therefore makes it possible to reduce the quantity of materials consumed, to reduce the mass of the motorization systems or even to better size the motors over the operating cycles.

[0011] We can cite the publication “Power factor correction of induction motors using PWM inverter fed auxiliary stator winding” I. Tamrakar and OP Malik, in IEEE Transactions on Energy Conversion, vol. 14, no. 3, pp. 426-432, Sept. 1999”, which discloses a traction chain comprising an electric motor and a reactive energy compensation device. The reactive energy compensation device is called SSSC, or “Static Synchronous Series Compensation”. The SSSC device comprises an auxiliary stator winding magnetically coupled to the machine. This auxiliary winding makes it possible to recover part of the energy stored in the winding phases (when they are magnetized) to store it in a capacitor of the SSSC. Then, this energy is restored during the re-magnetization phase and the auxiliary winding brings an additional flux into the stator of the machine.But using the SSSC device requires direct intervention within the machine and modification of its structure, in particular by resizing it, to be able to provide the additional flow.

[0012] An object of the present invention is therefore to provide means for increasing the mechanical / electrical power supplied by an electrical machine using a given power supply system which are simple and robust.

[0013] Other objects, features, and advantages of the present invention will become apparent from the following description and accompanying drawings. It is understood that other advantages may be incorporated.

[0014] SUMMARY OF THE INVENTION

[0015] According to one aspect of the invention, there is provided a power management method for an electrical machine, comprising:

[0016] - a supply of an electromechanical conversion chain, the chain comprising:

[0017] - a polyphase electric machine;

[0018] - a power supply system comprising a power converter and an electrical energy source or an electrical device, the electrical source or device being electrically coupled to the power converter, the power converter being configured to exchange an alternating voltage and current with the polyphase electrical machine, the power supply system being configured to exchange an apparent power depending on the alternating voltage and current with the polyphase electrical machine, the apparent power being equal to a vector sum of an active power and a reactive power;

[0019] - a control-command system configured to control, by means of an initial command, the power converter so that the power system exchanges with the polyphase electrical machine an initial apparent power equal to a vector sum of an initial active power and an initial reactive power; and

[0020] - a polyphase power interface electrically coupled between the power converter and the polyphase electrical machine, the polyphase power interface being configured to manage the reactive power exchanged between the power system and the polyphase electrical machine;

[0021] - the polyphase power interface and the power supply system forming a power management assembly, the assembly being configured to exchange the apparent power with the polyphase electrical machine.

[0022] The process includes:

[0023] - control, carried out by the polyphase power interface, of a power factor between the power converter and the polyphase power interface with respect to a power factor setpoint, so that the polyphase power interface provides at least part of the reactive power consumed by the polyphase electrical machine so that the power management assembly can exchange with the polyphase electrical machine an apparent power strictly greater than the initial apparent power.

[0024] Such control allows the electric machine to consume or produce an apparent power strictly greater than the apparent power consumed or produced during the initial command. In other words, thanks to the control, the power management assembly formed by the power supply system and the polyphase power interface is able to exchange with the electric machine an apparent power strictly greater than the initial apparent power. Thus, the mechanical power supplied by a motor can be increased with a given power supply system. Advantageously, the constituent elements of the power supply system and the electric machine are not modified, in other words the given size of the machine and the power supply system is retained.

[0025] According to another aspect, there is provided a power management device for an electrical machine, comprising an electromechanical conversion chain, the chain comprising:

[0026] - a polyphase electric machine;

[0027] - a power supply system comprising a power converter and an electrical energy source or an electrical device, the electrical source or device being electrically coupled to the power converter, the power converter being configured to exchange an alternating voltage and current with the polyphase electrical machine, the power supply system being configured to exchange an apparent power depending on the alternating voltage and current with the polyphase electrical machine, the apparent power being equal to a vector sum of an active power and a reactive power;

[0028] - a control-command system configured to control, by means of an initial command, the power converter so that the power system exchanges with the polyphase electrical machine an initial apparent power equal to a vector sum of an initial active power and an initial reactive power; and

[0029] - a polyphase power interface electrically coupled between the power converter and the electrical machine, the polyphase power interface being configured to manage the reactive power exchanged between the power system and the polyphase electrical machine;

[0030] - the polyphase power interface and the power supply system forming a power management assembly, the assembly being configured to exchange the apparent power with the polyphase electrical machine.

[0031] The control device comprises an electronic control unit configured to control the polyphase power interface such that the polyphase power interface controls a power factor between the power converter and the polyphase power interface relative to a power factor setpoint, such that the polyphase power interface provides at least a portion of the reactive power consumed by the polyphase electrical machine so that the power management assembly can exchange with the polyphase electrical machine an apparent power strictly greater than the initial apparent power. BRIEF DESCRIPTION OF THE FIGURES

[0032] The aims, objects, as well as the characteristics and advantages of the invention will emerge more clearly from the detailed description of an embodiment thereof which is illustrated by the following accompanying drawings in which: Figure 1 schematically illustrates one embodiment of a control device for an electric machine; Figure 2 schematically illustrates another embodiment of a control device where the polyphase power interface is electrically coupled in series; Figure 3 schematically illustrates another embodiment of a control device where the polyphase power interface is electrically coupled in parallel; Figure 4 schematically illustrates a vector representation of the initial powers exchanged between the electric machine and the power management assembly;Figure 5 schematically illustrates a vector representation of the powers exchanged between the electrical machine and the power management assembly during power factor control; Figure 6 schematically illustrates a representation of the alternating voltages exchanged between the electrical machine and the power management assembly, when the polyphase power interface is electrically coupled in series with the electrical machine and the power converter; Figure 7 schematically illustrates an embodiment of an electronic control unit; Figure 8 schematically illustrates an embodiment of a power interface; and Figure 9 schematically illustrates a curve representative of the operating limits of an electrical machine as a function of the rotational speed of the rotor of the machine.;

[0033] The drawings are given by way of example and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily to the scale of practical applications.

[0034] DETAILED DESCRIPTION OF THE INVENTION

[0035] Before beginning a detailed review of embodiments and implementations of the invention, optional features are set out below which may possibly be used in combination or alternatively. According to one example, the method comprises, during control, a so-called speed control, intended for the polyphase electrical machine so as to increase an active power converted by the polyphase electrical machine so that the active power exchanged between the power management assembly and the polyphase electrical machine is strictly greater than the initial active power.

[0036] According to one example, the method comprises, during control, a command, called flux command, intended for the polyphase electric machine so as to increase the magnetic flux of the polyphase electric machine so that the polyphase power interface provides the polyphase electric machine with reactive power strictly greater than the initial reactive power, and so that the active power exchanged between the power management assembly and the polyphase electric machine is strictly greater than the initial active power.

[0037] In one example, the flux control includes increasing a torque setpoint of the polyphase electric machine beyond the value of the torque setpoint of the polyphase electric machine during the initial control.

[0038] In one example, the flux control includes increasing a magnetic flux setpoint of the polyphase electrical machine beyond the value of the magnetic flux setpoint of the polyphase machine during the initial control.

[0039] According to one example, the control further comprises a determination of an initial power factor between the power converter and the polyphase electrical machine, preferably when the polyphase power interface is transparent. For example, the polyphase power interface is transparent when it does not exchange any reactive power with the polyphase electrical machine. Advantageously, the power factor setpoint is strictly greater than the initial power factor.

[0040] According to one example, the power factor setpoint FPref is between 0.7 and 1 and preferably between 0.85 and 1 or between 0.9 and 1 and, more preferably, between 0.95 and 1, or even between 0.97 and 1.

[0041] For example, piloting includes:

[0042] - a determination of the power factor from an angular phase shift between the alternating voltage and current present between the power converter and the polyphase power interface,

[0043] - generation of a command from a difference between the power factor setpoint and the determined power factor, and

[0044] - a control of the polyphase power interface from the control so as to regulate the power factor in relation to the power factor setpoint.

[0045] In one example, the polyphase electric machine is an electric motor and the power system includes an electrical power source electrically coupled to the power converter, and when driven, the power system provides the electric motor with the active power consumed by the electric motor.

[0046] In one example, the polyphase electrical machine is an electrical generator and the power system includes an electrical device electrically coupled to the power converter, and when driven, the electrical generator supplies the electrical device with the active power consumed by the electrical device.

[0047] In one example, control is performed when the amplitude and frequency of alternating voltage and current vary over time.

[0048] According to one example, when the polyphase power interface controls the power factor, the electronic control unit is configured to transmit to the control-command system a command, called a speed command, so as to increase an active power converted by the electrical machine so that the active power exchanged between the power management assembly and the polyphase electrical machine is strictly greater than the initial active power.

[0049] According to one example, when the polyphase power interface controls the power factor, the electronic control unit is configured to transmit to the control-command system a command, called a flux command, intended for the polyphase electrical machine so as to increase the magnetic flux of the polyphase electrical machine so that the polyphase power interface provides the polyphase electrical machine with reactive power strictly greater than the initial reactive power, and so that the active power exchanged between the power management assembly and the polyphase electrical machine is strictly greater than the initial active power.

[0050] According to one example, the electronic control unit comprises a comparator configured to determine the power factor from an angular phase shift between the alternating voltage and current present between the power converter and the polyphase power interface, and a command generator configured to determine a command from a difference between the power factor setpoint and the determined power factor, the command generator being configured to control the polyphase power interface from the command so as to regulate the power factor with respect to the power factor setpoint.

[0051] In one example, the polyphase power interface is electrically coupled in series with the polyphase electrical machine and the power converter.

[0052] In one example, the polyphase electrical machine and the power converter are electrically coupled in series and the polyphase power interface is electrically coupled in parallel between the polyphase electrical machine and the power converter.

[0053] In one example, the polyphase electrical machine is an electric motor and the power system includes an electrical power source electrically coupled to the power converter, and when the polyphase power interface drives the power factor, the power system is configured to provide the electric motor with the active power consumed by the electric motor.

[0054] In one example, the polyphase electrical machine is an electrical generator and the power system includes an electrical appliance electrically coupled to the power converter, and when the polyphase power interface drives the power factor, the electrical generator is configured to provide the electrical appliance with the active power consumed by the electrical appliance.

[0055] In one example, the polyphase power interface is configured to control the power factor when the amplitude and frequency of the alternating voltage and current vary over time.

[0056] It is specified that in the context of the present invention, the expressions "A coupled to B", "A electrically coupled to B", "A connected to B" or "A electrically connected to B" are synonymous with "A is in electrical connection with B" and do not necessarily mean that there is no member between A and B. Thus these expressions are understood to mean an electrical connection between two elements, this connection may or may not be direct, this means that it is possible that between a first device A and a second device B which are electrically connected, connected or coupled, a current flows in A, in B, and on the path connecting A to B, this path may or may not include other electrical equipment.

[0057] Conversely, in the context of the present invention, the term "electrically directly connected" or "directly connected" means a direct electrical connection between two elements. This means that between a first device A and a second device B which are electrically directly connected no other equipment is present, other than one or more electrical connections.

[0058] It is specified that in the context of the present invention, the term "electrically placed" or "electrically located" means positioning a device on a line in which a current flows.

[0059] It is specified that in the context of the present invention, the term "A electrically coupled between B and C" means a positioning of a device A on a line connecting B to C in which a current flows between A, B and C. The device A can be electrically coupled to B and C, either in series or in parallel.

[0060] It should be noted that throughout the present invention, the above-mentioned line is used to represent a vector, thus the notation A corresponds to the vector A. Furthermore, it will be noted that a vector A, noted A, is greater than, or strictly greater than, a vector B, noted s, when the norm of A, that is to say the scalar value of A, is greater than, or strictly greater than, the norm of B, that is to say the scalar value of B. It will also be noted that a vector A, noted A, is equal to, less than, or strictly less than, a vector B, noted B, when the norm of A is equal to, less than, or strictly less than the norm of B.

[0061] In Figures 1 to 3, an electromechanical conversion chain 100 is shown comprising a polyphase electric machine 2, hereinafter referred to as electric machine 2, a power supply system 3, and a control device 1 for the electric machine 2. In general, the polyphase electric machine 2 is configured to convert electrical energy into mechanical energy (when the electric machine operates in motor mode) or mechanical energy into electrical energy (when the electric machine operates in generator mode). The electric machine 2 comprises a stator having several coils and a rotor with separate or non-separated excitation and controlled or non-controlled, for example a synchronous machine with permanent magnets or a wound rotor, an asynchronous machine with a cage or a wound rotor, or a synchronous-reluctant or variable reluctance machine.

[0062] When the electrical machine 2 operates in motor mode, the electrical machine consumes a current and a voltage to provide mechanical torque. When the electrical machine 2 operates in generator mode, the electrical machine 2 provides an electrical current and voltage to the power system 3. In particular, the electrical machine is polyphase, that is, the electrical machine 2 is coupled to a polyphase electrical system. Generally, the power converter 5 is electrically coupled to the power source 4, or to the electrical appliance 400, by an electrical connection having M phases (with M an integer). M may be equal to 2, in the case of direct current, or equal to 3 for alternating current. Furthermore, the electrical machine 2 is electrically coupled to the power converter 5 by another electrical connection having N phases (with N an integer greater than or equal to 2).For example, as shown in Figures 2 and 3, M is equal to 2 and N is equal to 3. In this case, the electric machine 2 is three-phase, that is, the electric machine 2 is coupled to three phases A, B, C.

[0063] Furthermore, the power supply system 3 comprises a power converter 5 and a source 4 of electrical energy or an electrical appliance 400. For example, the source of electrical energy 4 is electrically coupled to the converter 5. According to another embodiment, the electrical appliance 400 is electrically coupled to the power converter 5, instead of the source 4. The source 4 may be a current source or a voltage source. The source may also be an electrical energy distribution network for providing alternating voltage and current. For example, the source 4 is a battery, for storing and / or providing electrical energy, in particular from direct voltage and current.

[0064] Generally, the power converter 5 is configured to exchange an alternating voltage and current with the electrical machine 2. In the case where the power supply system 3 comprises an electrical energy source 4, the power converter 5 may be configured to convert a direct voltage and current supplied by the source 4 into an alternating voltage and current intended for the electrical machine 2 during engine operation. For example, the power converter 5 is variable frequency. For example, the power converter 5 may be an inverter or a drive. In the case where the power supply system 3 comprises an electrical appliance, the power converter 5 is configured to convert an alternating voltage and current supplied by the electrical machine 2 into a direct or alternating voltage and current intended for the electrical appliance 400 during generator operation.For example, the power converter 5 can be a diode or controlled rectifier.

[0065] For example, as illustrated in Figure 2, the converter 5 comprises, for each phase A, B, C, of ​​the electrical machine 2 a group of two switches 6, 7 electrically coupled together in series. For each phase A, B, C, the two switches 6, 7 of the group are coupled in parallel with the source 4. For each phase A, B, C, the group of two switches 6, 7 provides an alternating voltage and current on an output terminal of the converter G1 to G3 associated with the group. The output terminal G1 to G3 of the converter 5 associated with a group is coupled between the two switches of the group. Furthermore, each switch 6, 7 of the converter comprises a diode 8 mounted in parallel across the terminals of the switch 6, 7.

[0066] Furthermore, the power system 3 is configured to exchange an apparent power Sm depending on the alternating voltage and current with the electrical machine 2. The apparent power Sm is equal to a vector sum of an active power Pm and a reactive power Qm, as shown in Figure 5. The unit of an active power is expressed in Watts, the unit of a reactive power is expressed in Volt-Amperes Reactive and the unit of an apparent power is expressed in Volt-Amperes.

[0067] The electromechanical conversion chain 100 may further comprise a control-command system 101 configured to control a torque supplied by the motor 2 as a function of the currents absorbed by the motor 2 (regardless of the control strategy, the algorithm or the measurements used). The control-command system 101 is also configured to control the magnetic flux level of the electrical machine 2. The electromechanical conversion chain 100 may operate at a variable operating point, with a variable level of torque supplied and speed (and therefore power). This operating point is however located within a zone restricted by different operating limits. These limits are directly linked to the limits of the different components of the chain 100, the most constrained component imposing the limits of the entire chain 100. Figure 9 schematically presents these different limits.In particular, a curve 102 of the torque T of the electric machine 2 has been represented as a function of the speed vr of rotation of the rotor of the electric machine 2. We can note in figure 9, a limit in maximum current and in associated maximum torque. The level of magnetic flux in the electric machine.

[0068] 2 may be at its nominal value and operation is limited by thermal considerations (heating) which limit the current level in the electromechanical conversion chain 100. The power then increases with the rotation speed. Curve 102 also represents a maximum voltage limit supplied by the converter 5. This limit is linked to the voltage level that the power supply system

[0069] 3 is capable of exchanging with the electric machine 2 (according to the control-command strategy). Curve 102 therefore delimits an initial operating zone of the electromechanical conversion chain 100. It is noted that the power then decreases progressively with the rotation speed of the rotor.

[0070] Generally, the control-command system 101 is configured to control, by means of an initial command, the power converter 5 so that the power supply system 3 exchanges with the polyphase electrical machine 2 an initial apparent power Sminit equal to a vector sum of an initial active power Pminit and an initial reactive power Qminit, as illustrated in FIG. 4.

[0071] Furthermore, the device 1 comprises a polyphase power interface 9, also referred to as power interface 9 or interface 9, electrically coupled between the power converter 5 and the polyphase electrical machine 2, as illustrated in FIG. 1. The interface 9 can be electrically coupled in series between the power converter 5 and the electrical machine 2, as illustrated in FIG. 2. The interface 9 can be electrically coupled in parallel between the power converter 5 and the electrical machine 2, as illustrated in FIG. 3. Generally, the polyphase power interface 9 is configured to manage the reactive power Qm exchanged between the power system 3 and the polyphase electrical machine 2.

[0072] The polyphase power interface 9 and the power supply system 3 form a power management assembly 90. The assembly 90 is configured to exchange the apparent power Sm with the polyphase electrical machine 2.

[0073] For example, the interface 9 has at least one input terminal e1 to e3 electrically coupled to the power converter 5 and at least one output terminal s1 to s3 electrically coupled to the electrical machine 2. More particularly, for each phase A, B, C of the electrical machine 2, the interface 9 comprises an input terminal e1 to e3 electrically coupled to a respective output terminal G1 to G3 of the converter 5. Furthermore, for each phase A, B, C of the electrical machine 2, the interface 9 comprises an output terminal s1 to s3 electrically coupled to a respective phase A, B, C of the electrical machine 2. The interface 9 further comprises controlled switches 10 to 13 electrically coupled between the input terminals e1 to e3 and output terminals s1 to s3.A controlled switch 10 to 13 can be an IGBT transistor (or "Insulated Gate Bipolar Transistor" in English, i.e. a bipolar transistor with an insulated gate), or a MOSFET (or "Metal Oxide Semiconductor Field Effect Transistor" in English, i.e. a metal oxide field effect transistor).

[0074] In particular, for each phase A, B, C of the machine 2, the interface 9 comprises a group GA, GB, GC, of ​​at least two switches 10 to 13. Furthermore, each group GA, GB, GC of the interface 9 may comprise a capacitive system Ca electrically coupled between a respective input terminal e1, e2, e3 of the interface 9 and a respective output terminal s1, s2, s3 of the interface 9.

[0075] According to one embodiment, called in series, as illustrated in FIG. 2, the power interface 9 is configured to be electrically coupled in series with the electrical machine 2 and the power converter 5. For example, each group GA, GB, GC of the interface 9 comprises four switches 10 to 13 coupled between a respective input terminal e1, e2, e3 of the interface 9 and a respective output terminal s1, s2, s3 of the interface 9. More particularly, each group GA, GB, GC of the interface 9 comprises two first switches 10, 11 electrically coupled together in series and two second switches 12, 13 electrically coupled together in series. For each group GA, GB, GG of the interface 9, the two first switches 10, 11 are coupled in parallel with the second switches 12, 13.For example, each group GA, GB, GC of the interface 9 comprises a diode 14 mounted in parallel across the terminals of each IGBT type switch 10 to 13 of the group GA, GB, GC. Furthermore, each group GA, GB, GC of the interface 9 comprises a capacitive system Ca electrically coupled in parallel with the first two switches 10, 11, and in parallel with the second switches 12, 13.

[0076] According to another embodiment, called in parallel, the electrical machine 2 and the power converter 5 are electrically coupled in series and the power interface 9 is configured to be electrically coupled in parallel between the electrical machine 2 and the power converter 5. For example, each group GA, GB, GC of the interface 9 comprises first and second switches 10, 11. Each first switch 10 is connected in series between a respective input terminal e1, e2, e3 of the interface 9 and a respective output terminal s1, s2, s3 of the interface 9. Furthermore, each group GA, GB, GC comprises a capacitive system Ca electrically coupled in series with the second switch 11 of the interface 9, between the output terminal e1, e2, e3 of the group and a reference voltage Vref. In Figure 8, a group GA of the interface 9 is shown having two switches 10, 11 and a capacitive system Ca.

[0077] The device 1 further comprises an electronic control unit 20 configured to control the polyphase power interface 9. In particular, the electronic control unit 20 is configured to control the switches 10 to 13 of the interface 9, by a main connection C1 connecting the electronic control unit 20 and the switches 10 to 13.

[0078] Generally, the electronic control unit 20 is configured to control the power interface 9 so as to control a power factor FPmes between the power converter 5 and the power interface 9 with respect to a power factor setpoint FPref. The power factor FPref is a function of the angular phase shift teta between the voltage and the current. The power factor FPmes can be obtained by the relation FPmes = cos(teta), where the angular phase shift teta is expressed in radians and the power factor FPmes is unitless. We also have the relation teta = œ * tr, where œ corresponds to the pulsation of the currents and voltages expressed in radians / sec and tr corresponds to the time phase shift between the voltage and the current, expressed in seconds. The control can be a regulation of the power factor, and it is also said that the power interface regulates the power factor FPmes.The regulation is also called closed-loop power factor control. Alternatively, the control can be a power factor control, and the power interface is also said to control the power factor FPmes. The control is also called open-loop power factor control. In other words, the control tends to bring the power factor FPmes closer to the power factor setpoint value FPref. The power factor control FPmes aims to cancel the phase shift between the voltage and current exchanged between the power system 3 and the electrical machine 2. Thus, when the power interface 9 controls the power factor FPmes, the polyphase power interface 9 provides at least a portion Qint of the reactive power consumed Qm by the polyphase electrical machine 2, as illustrated in Figure 5.Thus, the power management assembly 90 can exchange with the polyphase electrical machine 2 an apparent power Sm strictly greater than the initial apparent power Sminit.

[0079] Advantageously, the setpoint FPref is close to 1, for example the setpoint FPref is between 0.9 and 1. Preferably, the value of the setpoint FPref is equal to 1. Thus, when the setpoint FPref is close to 1, the phase shift between the voltage and the current is close to 0, when the setpoint FPref is equal to 1, the phase shift is zero. Thus, when the phase shift is zero or close to 0, that is to say between 25.84° (when the power factor FPmes = 0.9) and 0° (when the power factor FPmes = 1), the power interface 9 provides the reactive power Qm consumed by the electrical machine 2. In addition, the power management assembly 90 exchanges the active power Pm with the electrical machine 2.Thus, the power interface 9 provides all or part of the reactive power consumed Qm by the electrical machine 2 and the power supply system 3 provides or receives, depending on whether the electrical machine operates respectively in motor mode or in generator mode, the initial active power Pminit consumed or produced by the electrical machine 2. The power supply system 3 does not provide any reactive energy (when the power factor FPmes = 1) or part of the reactive power consumed by the electrical machine 2 (when the power factor FPmes is close to 1).

[0080] The control according to the invention has an advantage when the power supply system 3 provides or receives less reactive energy than in normal operation, without a power interface (the ideal being, as presented above, that the power supply system 3 does not have to provide or receive any reactive energy). It is therefore sufficient that the power interface 9 provides at least a portion of the reactive power Qm consumed by the electrical machine 2. The FPref setpoint to be considered for the control must therefore be chosen so as to satisfy this minimum condition. It is satisfied if the FPref setpoint is greater than the power factor of the machine in the absence of a power interface (which we will indicate by FPinit). A measurement of the power factor of the machine in the absence of the power interface 9 can make it possible to determine the FPinit factor of the machine.Therefore, selecting FPref in the range ] FPinit ; 1] (the semi-open range " ] a ; b ]" meaning that "a" is not included in the range) makes it possible to obtain a measurable gain in the operation of the machine. The FPinit factor depends on the machine and its operation. However, it is generally less than 0.7. An FPref setpoint included in the range ]0.7 ; 1] is therefore likely to improve the control of the machine 2, without however resorting to a prior measurement of FPinit. The FPref setpoint is preferably chosen in the range [0.85 ; 1] or, even more preferably, in the range [0.9 ; 1].

[0081] For a synchronous motor, the FPinit can be high, for example equal to 0.95. For this type of motor, we will therefore preferentially choose a higher FPref setpoint, for example between ]0.95; 1] or, preferably, between the range [0.97; 1],

[0082] In Figure 7, an embodiment of the electronic control unit 20 is shown. According to this embodiment, the electronic control unit 20 comprises a comparator 21 and a control generator 22. For example, the electronic control unit 20 may be a microprocessor, a programmable logic controller or a microcontroller. The comparator 21 is configured to determine the power factor FPmes from an angular phase shift teta between the alternating voltage U and current I at an input terminal e1, e2, e3 of the interface 9. For example, the device 1 comprises a measuring system 23 coupled to each input terminal e1 to e3 of the interface 9 and to the electronic control unit 20, by second and third connections C2, C3. The measuring system 23 is configured to measure, for each phase A, B, C of the machine 2, the alternating voltage UA,B,C and the alternating current IA,B,C at each input terminal e1 to e3 of the interface 9.The measuring system 23 transmits, to the electronic control unit 20, the measured alternating voltage UA,B,C, via the second connection C2, and the alternating current I. A ,B,C measured, by the third connection C3. The electronic control unit 20 may comprise a bandpass filter 24 to remove the harmonics of the currents and voltages linked to the disturbances created by the power converter 5, in order to transmit sinusoidal signals to the comparator 21. The comparator 21 calculates, for each phase A, B, C, the angular phase shift teta between the alternating voltage U and current I. Then, the comparator 21 determines the power factor FPmes from teta. The power factor FPmes can be calculated by the relation: FPmes = cos(teta). Advantageously, the comparator 21 determines, for each phase A, B, C, a power factor FPmes associated with the phase A, B, C.

[0083] Furthermore, the command generator 22 is configured to determine a beta command from a difference E between a power factor setpoint FPref and the determined power factor FPmes. For example, the beta command is generated on the basis of a delay, called the firing delay, applied to the current crossings to 0 Ampere. For example, the electronic control unit 20 comprises an additional comparator 25 configured to determine the difference E = FPref - FPmes. For example, the power factor setpoint FPref is equal to 1. The electronic control unit 20 may also comprise a corrector 26 configured to generate a firing delay angle delta from the difference E. The firing delay angle delta may be determined by the corrector 26, as illustrated in FIG. 7, for example from the difference between teta (or FPmes) measured and a reference value.The difference between the measurement and the reference is then processed by the corrector 26 which determines the delta triggering delay angle to be applied to the interface 9. Thus, the command generator 22 generates the beta command as a function of the delta triggering delay angle. The corrector 26 may be of the proportional type, or of the integral type, or of the proportional-integral type. For example, to generate the beta command to be applied to the switches 10 to 13 of the interface 9, a reference signal SLref may be used. For example, the reference signal SLref corresponds to the current, as illustrated in FIG. 7, when the machine 2 is current-driven. Alternatively, the reference signal SLref corresponds to the voltage when the machine 2 is voltage-driven. The command generator 22 may further comprise a comparison stage 27 configured to transform the sinusoidal reference signal SLref into a square signal.The command generator 22 may comprise a delay unit 28 configured to apply the delta firing delay angle to the obtained square signal, i.e. to delay the square signal by the delta value. In order to generate the beta command, the electronic control unit 20 comprises an intermediate stage 29 configured to continuously calculate the frequency f of the measured voltage and current, so as to be able to continuously adapt to variations in the frequency.

[0084] The control generator 22 is further configured to control the interface 9, and more particularly the switches 10 to 13, from the beta command so as to control the power factor FPmes with respect to the power factor setpoint FPref.

[0085] More particularly, the control generator 22 is configured to control the switches of the interface 9 from the beta control so that the capacitive system Ca is charged by demagnetizing the coils of the stator of the machine 2. Furthermore, the electronic control unit 20 is configured to control the switches of the interface 9 so as to discharge the capacitive system Ca to supply the reactive power Qint to each output terminal s1 to s3 of the interface 9.

[0086] For example, the control generator 22 is configured to control the switches of the interface 9 so that the charging of the capacitive system Ca is carried out for a determined time proportional to the ignition delay angle delta.

[0087] In general, the power supply system 3 exchanges, for each phase A, B, C, an apparent power Sc equal to a vector sum of an active power Pc and a reactive power Qc, where Pc corresponds to the active power exchanged between the power supply system 3 and the electrical machine 2; and Qc corresponds to the reactive power supplied by the power supply system 3 to the electrical machine 2.

[0088] Furthermore, when the power factor FPmes is controlled, the reactive power Qc supplied by the power supply system 3 tends towards the zero value, and each group GA, GB, GC of the interface 9, provides the reactive power Qint to the electric machine 2. The power supply system 3 then exchanges with the electric machine 2 an apparent power Sc equal to the active power Pc , and we have the relation Sc = Pc , as illustrated in Figure 5. It will be noted that initially, before control, the apparent power Sc exchanged between the power supply system 3 and the electric machine 2 is equal to an initial apparent power Scinit. Moreover, the initial apparent power Scinit is equal to the vector sum of an initial active power Pcinit and an initial reactive power Qcinit , as illustrated in Figure 4.Initially, when Qcinit is non-zero, then the initial apparent powerScinit is strictly greater than the initial active power Pcinit. Then, when the power factor FPmes is controlled, then Qcinit becomes zero or tends towards a value close to 0, and the power system 3 exchanges with the electrical machine 2 an apparent power Sc= Pc, and Sc= Pcinit, as illustrated in Figure 5.

[0089] In other words, during piloting, the active power Pm exchanged between the power management assembly 90 and the machine 2 is equal to the initial active power Pcinit, and we have the relationship Pm= Pcinit, and the reactive power Qm consumed by the motor 2 is supplied by the power interface 9, so that we have the relationship Qm= Qint as illustrated in Figure 5.

[0090] Generally, before or during control, the apparent power Sm exchanged between the machine 2 and the power management assembly 90 is equal to the vector sum of the active power exchanged Pm and the reactive power Qm consumed by the machine 2, as illustrated in figure 5.

[0091] The control of the power factor FPmes between the power converter 5 and the machine can be used to increase the active power Pc exchanged between the power supply system 3 and the machine 2, without modifying the structure of the elements of the power supply system 3 and without modifying the control strategy of the power converter 5. By control strategy of the power converter 5, we mean the fact that the control-command system 101 is configured to control the torque of the machine 2 by controlling the current consumed or supplied by the machine 2.

[0092] For example, the electronic control unit 20 is configured to transmit, via a connection C4, to the control-command system 101 a command, called a speed command, so as to increase an active power Pm converted by the electrical machine so that the active power Pm exchanged between the power management assembly 90 and the electrical machine 2 is strictly greater than the initial active power Pminit.

[0093] The speed command can be a speed setpoint of the machine 2 which involves a change in the torque setpoint. It will be noted that the active power Pc supplied or received by the power system 3 can increase until it reaches the value Scinit . We can therefore obtain the relationship Pc = Scinit . In other words, the active power Pm , exchanged between the power management assembly 90 and the electric machine 2, can increase and reach the value of the initial apparent power Scinit. Thus, we can increase the active power Pm converted by the machine 2 dynamically, without bringing additional constraints on the power system 3.

[0094] The correction of the power factor FPmes will have the effect of allowing the power supply system 3 to increase the active power Pc that it exchanges with the machine 2 compared to the initial active power Pcinit.

[0095] In this case, the power interface 9 supplies, at the output terminal s1 to s3, the reactive power Qm to the machine 2 which consumes it. Thus, the apparent power Sm exchanged between the power management assembly 90 and the machine 2 is increased without modifying or intervening on the power supply system 3.

[0096] In particular, when the polyphase power interface 9 is coupled in series, an alternating voltage Vm exchanged between the assembly 90 and the machine 2 can be increased.

[0097] In this case, the power supply system 3 exchanges with the machine 2 a first alternating voltage Vc at each input terminal e1 to e3 of the interface 9. Furthermore, the electronic control unit 20 is configured to control the switches 10 to 13 of the interface 9 so that the interface 9 controls the power factor and provides a second alternating voltage Vint at each output terminal s1 to s3 of the interface 9. Thus, the assembly 90 exchanges with the machine 2, the alternating voltage Vm equal to a vector sum of the first and second alternating voltages Vc, Vint, as illustrated in FIG. 6.

[0098] According to another embodiment, the interface is electrically coupled in parallel, and an alternating current Im exchanged between the assembly 90 and the machine 2 can be increased.

[0099] In this case, the power supply system 3 exchanges with the machine 2 a first alternating current at each input terminal e1 to e3 of the interface 9. Furthermore, the electronic control unit 20 is configured to control the switches 10 to 13 of the interface 9 so that the interface 9 controls the power factor and supplies a second alternating current to each output terminal s1 to s3 of the interface 9. Thus, the assembly 90 exchanges with the machine 2, an alternating current equal to a vector sum of the first and second alternating currents.

[0100] The electronic control unit 20 is further configured to transmit to the control-command system 101 a command, called a flux command, intended for the polyphase electrical machine. The flux command is intended to increase the magnetic flux in the air gap of the machine. , this flux being equal to the vector sum of a stator flux 4>s and a rotor flux 4>r. Advantageously, the flux control is intended to increase the torque of the electrical machine 2, in particular the torque of the rotor of the machine 2. Indeed, an increase in the flux in the air gap of the machine 2 can lead to an increase in the torque of the machine 2, the torque being proportional to a vector product between the stator flux in the air gap 4>s and the rotor flux in the air gap 4>r. When the polyphase power interface 9 controls the power factor FPmes, the flux control makes it possible to increase the magnetic flux of the polyphase electrical machine 2 so that the polyphase power interface 9 provides the polyphase electrical machine 2 with a reactive power Qint strictly greater than the initial reactive power Qminit.Thus, the reactive power Qm exchanged between the power management assembly 90 and the electrical machine 2 is strictly greater than the initial reactive power Qminit.

[0101] For example, the flux control comprises an increase in a torque setpoint of the polyphase electric machine beyond the value of the torque setpoint during the initial control. For example, when it is desired to increase the torque from an increase in the magnetic flux of the machine, the torque setpoint can be increased and either the stator flux setpoint 4>s can be increased, the rotor flux setpoint 4>r can be increased, or both the rotor flux setpoint 4>r and stator flux setpoint 4>s can be increased. The torque setpoint can also be increased, the stator current setpoint can be increased to increase 4>s and the rotor magnetic flux setpoint perceived by the stator 4>rs can be increased to increase 4>r. According to another example, the flux control comprises an increase in a magnetic flux setpoint of the polyphase electric machine beyond the value of the magnetic flux setpoint of the machine during the initial control.

[0102] According to yet another advantage, the polyphase power interface 9 is configured to control the power factor FPmes when the amplitude and frequency of the alternating voltage and current vary over time. The control device 1 defined above can be used to implement a control method for the electrical machine 2.

[0103] The process includes the following main steps:

[0104] - a supply of an electromechanical conversion chain 100 as defined above, and

[0105] - control, carried out by the polyphase power interface 9, of a power factor FPmes between the power converter 5 and the polyphase power interface 9 with respect to a power factor setpoint FPref.

[0106] The power factor control allows the polyphase power interface 9 to provide at least a portion Qint of the reactive power consumed Qm by the polyphase electrical machine 2. Thus, the power management assembly 90 can exchange with the polyphase electrical machine 2 an apparent power Sm strictly greater than the initial apparent power Sminit. The device and the method which have just been described are particularly suitable for various applications, such as mobility, industry, robotics, household appliances, home automation, etc.

Claims

CLAIMS 1. A method for power management for an electrical machine, comprising: providing an electromechanical conversion chain (100), the chain comprising: a polyphase electrical machine (2); a power supply system (3) comprising a power converter (5) and an electrical energy source (4) or an electrical appliance (400), the source (4) or the electrical appliance (400) being electrically coupled to the power converter (5), the power converter (5) being configured to exchange an alternating voltage and current with the polyphase electrical machine (2), the power supply system (3) being configured to exchange an apparent power (Sm) as a function of the alternating voltage and current with the polyphase electrical machine (2), the apparent power (Sm being equal to a vector sum of an active power (Pm) and a reactive power (Çm);and a control-command system (101) configured to control, by means of an initial command, the power converter (5) so that the power supply system (3) exchanges with the polyphase electric machine (2) an initial apparent power (Sminit) equal to a vector sum of an initial active power (Pminit) and an initial reactive power (Qminit and a polyphase power interface (9) electrically coupled between the power converter (5) and the polyphase electric machine (2), the polyphase power interface (9) being configured to manage the reactive power (Çm) exchanged between the power supply system (3) and the polyphase electric machine (2); the polyphase power interface (9) and the power supply system (3) forming a power management assembly (90), the assembly (90) being configured to exchange the apparent power (Sm) with the polyphase electric machine (2);characterized in that the method comprises:; a control, carried out by the polyphase power interface (9), of a power factor (FPmes) between the power converter (5) and the polyphase power interface (9) with respect to a power factor setpoint (FPref), so that the polyphase power interface (9) provides at least a part (Qint) of the reactive power consumed (Qm) by the polyphase electrical machine (2) so that the power management assembly (90) can exchange with the polyphase electrical machine (2) an apparent power (Sm) strictly greater than the initial apparent power (Sminit).

2. Method according to the preceding claim, comprising, during control, a command, called speed, intended for the polyphase electric machine (2) so as to increase an active power (Pm) converted by the polyphase electric machine (2) so that the active power (Pm) exchanged between the power management assembly (90) and the polyphase electric machine (2) is strictly greater than the initial active power (Pminit).

3. Method according to any one of the preceding claims, comprising, during control, a command, called flux command, intended for the polyphase electric machine (2) so as to increase the magnetic flux of the polyphase electric machine (2) so that the polyphase power interface (9) provides the polyphase electric machine (2) with reactive power (Çm) strictly greater than the initial reactive power (Qminit), and so that the active power (Pm) exchanged between the power management assembly (90) and the polyphase electric machine (2) is strictly greater than the initial active power (Pminit).

4. Method according to the preceding claim, in which the flux control comprises an increase in a torque setpoint of the polyphase electric machine (2) beyond the value of the torque setpoint of the polyphase electric machine (2) during the initial control.

5. Method according to any one of claims 3 or 4, wherein the flux control comprises an increase in a magnetic flux setpoint of the polyphase electrical machine (2) beyond the value of the magnetic flux setpoint of the polyphase machine (2) during the initial control.

6. Method according to any one of the preceding claims, in which the control comprises: a determination of the power factor (FPmes) from an angular phase shift (teta) between the voltage and the current alternating currents present between the power converter (5) and the polyphase power interface (9), a generation of a command (beta) from a difference between the power factor setpoint (FPref) and the determined power factor (FPmes), and a command of the polyphase power interface (9) from the command (beta) so as to regulate the power factor (FPmes) with respect to the power factor setpoint (FPref).

7. Method according to any one of the preceding claims, in which the polyphase electrical machine (2) is an electric motor and the power supply system (3) comprises an electrical energy source (4) electrically coupled to the power converter (5), and during control, the power supply system (3) supplies the electric motor with the active power (Pm) consumed by the electric motor.

8. Method according to any one of claims 1 to 6, in which the polyphase electrical machine (2) is an electrical generator and the power supply system (3) comprises an electrical apparatus (400) electrically coupled to the power converter (5), and during control, the electrical generator supplies the electrical apparatus (400) with the active power (Pm) consumed by the electrical apparatus (400).

9. A method according to any preceding claim, wherein the control is performed when the amplitude and frequency of the alternating voltage and current vary over time.

10. Power management device for an electrical machine, comprising an electromechanical conversion chain (100), the chain comprising: a polyphase electrical machine (2); a power supply system (3) comprising a power converter (5) and an electrical energy source (4) or an electrical appliance (400), the source (4) or the electrical appliance (400) being electrically coupled to the power converter (5), the power converter (5) being configured to exchange an alternating voltage and current with the polyphase electrical machine (2), the power supply system (3) being configured to exchange an apparent power (Sm) depending on the alternating voltage and current with the polyphase electrical machine (2), the apparent power (Sm) being equal to a vector sum of an active power (Pm) and a reactive power (Çm); a control-command system (101) configured to control, by means of an initial command, the power converter (5) so that the power supply system (3) exchanges with the polyphase electrical machine (2) an initial apparent power (Sminit) equal to a vector sum of an initial active power (Pminit) and an initial reactive power (Qminit and a polyphase power interface (9) electrically coupled between the power converter (5) and the electrical machine (2), the polyphase power interface (9) being configured to manage the reactive power (Qm) exchanged between the power supply system (3) and the polyphase electrical machine (2);the polyphase power interface (9) and the power supply system (3) forming a power management assembly (90), the assembly (90) being configured to exchange the apparent power (Sm) with the polyphase electrical machine (2);characterized in that the control device comprises an electronic control unit (20) configured to control the polyphase power interface (9) so that the polyphase power interface (9) controls a power factor (FPmes) between the power converter (5) and the polyphase power interface (9) with respect to a power factor setpoint (FPref), so that the polyphase power interface (9) provides at least a portion (Qint) of the reactive power consumed (Qm by the polyphase electrical machine (2) so that the power management assembly (90) can exchange with the polyphase electrical machine (2) an apparent power (Sm) strictly greater than the initial apparent power (Sminit).; 11. Device according to the preceding claim, in which, when the polyphase power interface (9) controls the power factor (FPmes), the electronic control unit (20) is configured to transmit to the control-command system (101) a command, called a speed command, so as to increase an active power (Pm) converted by the electrical machine (2) so that the power active power (Pm) exchanged between the power management assembly (90) and the polyphase electrical machine (2) is strictly greater than the initial active power (Pminit).

12. Device according to any one of claims 10 or 11, wherein, when the polyphase power interface (9) controls the power factor (FPmes), the electronic control unit (20) is configured to transmit to the control-command system (101) a command, called a flux command, intended for the polyphase electrical machine (2) so as to increase the magnetic flux of the polyphase electrical machine (2) so that the polyphase power interface (9) provides the polyphase electrical machine (2) with a reactive power (Qm) strictly greater than the initial reactive power (Qminit), and so that the active power (Pm) exchanged between the power management assembly (90) and the polyphase electrical machine (2) is strictly greater than the initial active power (Pminit).

13. Device according to the preceding claim, in which the flux control comprises an increase in a torque setpoint of the polyphase electric machine (2) beyond the value of the torque setpoint of the polyphase electric machine (2) during the initial control.

14. Device according to any one of claims 12 or 13, wherein the flux control comprises an increase in a magnetic flux setpoint of the polyphase electrical machine (2) beyond the value of the magnetic flux setpoint of the polyphase machine (2) during the initial control.

15. Device according to any one of claims 10 to 14, wherein the electronic control unit (20) comprises a comparator (21) configured to determine the power factor (FPmes) from an angular phase shift (teta) between the alternating voltage and current present between the power converter (5) and the polyphase power interface (9), and a command generator (22) configured to determine a command (beta) from a difference between the power factor setpoint (FPref) and the determined power factor (FPmes), the command generator (22) being configured to control the polyphase power interface (9) from the command (beta) so as to regulate the power factor (FPmes) with respect to the power factor setpoint (FPref).

16. Device according to any one of claims 10 to 15, wherein the polyphase power interface (9) is electrically coupled in series with the polyphase electrical machine (2) and the power converter (5).

17. Device according to any one of claims 10 to 15, wherein the polyphase electrical machine (2) and the power converter (5) are electrically coupled in series and the polyphase power interface (9) is electrically coupled in parallel between the polyphase electrical machine (2) and the power converter (5).

18. Device according to any one of claims 10 to 17, wherein the polyphase electrical machine (2) is an electric motor and the power supply system (3) comprises an electrical energy source (4) electrically coupled to the power converter (5), and when the polyphase power interface (9) controls the power factor (FPmes), the power supply system (3) is configured to supply the electric motor with the active power (Pm) consumed by the electric motor.

19. Device according to any one of claims 10 to 17, wherein the polyphase electrical machine (2) is an electrical generator and the power supply system (3) comprises an electrical apparatus (400) electrically coupled to the power converter (5), and when the polyphase power interface (9) controls the power factor (FPmes), the electrical generator is configured to supply the electrical apparatus (400) with the active power (Pm) consumed by the electrical apparatus (400).

20. Device according to any one of claims 10 to 19, wherein the polyphase power interface (9) is configured to control the power factor (FPmes) when the amplitude and frequency of the alternating voltage and current vary over time.

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