METHOD FOR CONTROLLING A ROTATING ELECTRICAL MACHINE IN A PASSIVE STATE

Abstract

The present invention relates to a method for controlling a rotating electrical machine (12) integrated into a hybrid powertrain (10) of an automobile vehicle, said method comprising, when the rotating electrical machine (12) is in a passive state: - a step of controlling the rotating electrical machine (12) in an open-circuit mode in which the electronic switches of the inverter are open, - a step of controlling the electrical machine (12) in a short-circuit mode in which the electronic switches of the inverter (20) are in the closed state, and - a step of controlling the electrical machine (12) in an intermediate energy-optimization mode in which the overall energy consumption of the powertrain (10) is reduced compared to the short-circuit mode. Figure 1

Description

Title of the invention: METHOD FOR CONTROLLING A ROTATING ELECTRICAL MACHINE IN A PASSIVE STATE

[0001] The present invention relates to a method for controlling a rotating electrical machine in a passive state. The invention finds a particularly advantageous application for motor vehicles equipped with a hybrid powertrain.

[0002] In a manner known per se, a hybrid powertrain for a motor vehicle consists of an internal combustion engine coupled to a rotating electric machine electrically connected to a battery in an electrical network. The electric machine may be located on either the front or rear axle. The electric machine may be mechanically linked to the internal combustion engine by means of a belt, or integrated into a gearbox, a clutch, or any other component of the powertrain.

[0003] Conventionally, a rotating electrical machine comprises a rotor and a stator having a plurality of phases electrically connected to an inverter. For this purpose, the inverter includes a plurality of switching arms electrically connected in parallel. Each arm includes an upper-side switch and a lower-side switch connected to each other at a midpoint, each midpoint being intended to be connected to at least one phase of a rotating electrical machine.

[0004] A control module controls the opening or closing of each switch to control the power supply to the electrical machine. The bottom-side switches or the top-side switches are electronic power supply switches, for example, of the metal-oxide-semiconductor field-effect transistor (MOSFET) type. The intrinsic diode of such a transistor has the characteristic of being current-bidirectional.

[0005] The switches allow the electric machine to operate either in motor mode from a battery supplying power to the vehicle's electrical system, or in alternator mode to supply power to the vehicle's electrical system and recharge the vehicle's battery. In the case of an electric machine with three stator phases, the voltage converter includes three switches on the lower side, each connected to one of the three phases and to ground, and three switches on the upper side, each connected to one of the three phases and to a positive terminal of the vehicle's electrical system battery.

[0006] During certain phases of a motor vehicle's life, the electrical machine is required to be at rest in a "passive" state, also known as the "idle" state. This state "Passive" is implemented when the intention of a traction chain supervisory computer is not to supply power to the electrical network or not to draw mechanical power, or in the event of a fault in the rotating electrical machine.

[0007] However, an electrical machine with a rotor equipped with permanent magnets has the characteristic of a constant magnetic flux. Consequently, if the machine is driven to rotate during its operation in "passive" mode, this generates an electromotive force (EMF). Depending on the value of this EMF, the "passive" mode can lead to the power inverter being controlled in different ways.

[0008] When the rotational speed of the electric machine is low, the electric machine is operated in an open-circuit mode, also known as OC mode, in which the switches are open. This operating mode is acceptable as long as the electromotive force generated by the electric machine remains below the voltage of the vehicle's electrical network. However, when the electromotive force of the electric machine becomes greater than the voltage of the electrical network, an uncontrolled current can be injected by the electric machine into the vehicle's electrical network, which represents a safety risk.

[0009] To avoid this, the electric machine control module monitors the electromotive force or the rotational speed, which is also a representative value of the electromotive force.

[0010] When the electromotive force or the rotational speed reaches a threshold that could lead to the injection of an uncontrolled current, the electric machine is operated in an ASC short-circuit mode, also called ASC mode (for "Active Short Circuit"), in which all the electronic switches of the inverter are closed. This operating mode generates a parasitic torque on the shaft of the electric machine, which must be compensated by the internal combustion engine, thus consuming significant mechanical energy for this purpose.

[0011] The invention aims to effectively remedy this drawback by proposing a method for controlling a rotating electrical machine integrated into a hybrid powertrain of an automobile vehicle, said rotating electrical machine comprising a permanent magnet rotor and a plurality of phases electrically connected to an inverter equipped for each phase with a switching arm having an electronic switch on the top side and an electronic switch on the bottom side,

[0012] - said method comprising, when the rotating electrical machine is in a state passive:

[0013] - a step of controlling the rotating electrical machine in a circuit mode open in which the inverter's electronic switches are open, and

[0014] - a step of piloting the electric machine in a short-circuit mode in in which the inverter's electronic switches are in the closed state,

[0015] - said method further comprising a step of controlling the electrical machine in an intermediate energy optimization mode in which the overall energy consumption of the traction chain is reduced compared to the short-circuit mode,

[0016] - a transition from open-circuit mode to intermediate optimization mode energy occurring when a first switching criterion is met, and a switch from the intermediate torque compensation mode to the short-circuit mode occurring when a second switching criterion is met.

[0017] The invention thus makes it possible, through the introduction of the intermediate operating mode, to delay the transition to the short-circuit mode in which the internal combustion engine alone compensates for the parasitic torque of the shaft of the electric machine, while obtaining mechanical neutrality with respect to the operation of the internal combustion engine from which no torque is taken and / or electrical neutrality on the on-board network.

[0018] According to one embodiment of the invention, the first tipping criterion is a rotation speed criterion of the rotating electrical machine or a criterion of electromotive force generated by the rotating electrical machine.

[0019] According to one aspect of the invention, in the intermediate mode of energy optimization, the rotating electrical machine can be controlled by torque regulation to a substantially zero value, or the rotating electrical machine can be controlled by voltage regulation to a reference value, or the rotating electrical machine can be controlled by current regulation to a reference value of current drawn by the rotating electrical machine.

[0020] According to one embodiment of the invention, in the intermediate energy optimization mode, the rotating electric machine is controlled by torque regulation to a substantially zero value in order to compensate for a parasitic torque generated on the shaft of the electric machine due to a rotation of the permanent magnet rotor.

[0021] In this embodiment, the torque is kept substantially zero by consuming a small amount of energy from the battery. The mechanical impact is reduced. This advantageously optimizes overall energy consumption. The current drawn from the battery during this transient phase can be kept within a predefined range.

[0022] According to one embodiment of the invention, the second tipping criterion is a current consumption criterion of the rotating electrical machine.

[0023] According to one embodiment of the invention, in the intermediate energy optimization mode, the rotating electrical machine is controlled by voltage regulation to a reference value.

[0024] This embodiment provides a good compromise between electrical and mechanical neutrality. This embodiment also maintains the battery's state of charge.

[0025] According to one embodiment of the invention, the reference value is substantially equal to a voltage value of an on-board network of the motor vehicle.

[0026] According to one embodiment of the invention, the second tipping criterion is a torque criterion of the rotating electrical machine.

[0027] According to one embodiment of the invention, in the intermediate energy optimization mode, the rotating electrical machine is controlled by a current regulation to a reference value of current taken from the rotating electrical machine.

[0028] This embodiment achieves electrical neutrality. In this mode, the electric machine operates slightly in generator mode to compensate for these losses. This embodiment has no impact on the battery's state of charge. The impact on vehicle torque in this embodiment is negligible.

[0029] According to one embodiment of the invention, the reference current value is substantially zero current.

[0030] According to one embodiment of the invention, the second tipping criterion is a torque criterion.

[0031] According to one aspect of the invention, the rotor is a permanent magnet machine without external excitation. Alternatively, the rotor may include an excitation winding. The rotor may be a claw rotor. The rotor may be a wound rotor that also includes permanent magnets.

[0032] The present invention will be better understood and other features and advantages will become apparent upon reading the following detailed description, which includes embodiments given by way of illustration with reference to the accompanying figures, presented by way of non-limiting examples, which may serve to complete the understanding of the present invention and the explanation of its implementation and, where appropriate, contribute to its definition:

[0033] [Fig.1] Fig.1 is a schematic representation of different possible configurations of a hybrid traction chain implementing the method according to the invention;

[0034] [Fig.2] Fig.2 is a schematic representation of an electrical machine rotating and its inverter implementing the control method according to the invention when the electrical machine is in a passive state;

[0035] [Fig.3] Fig.3 is a diagram of the different operating modes of the rotating electric machine during the implementation of the piloting method according to the invention;

[0036] [Fig.4a][Fig.4b][Fig.4c] Figures 4a to 4c are functional diagrams of different types of control of the rotating electrical machine in the intermediate mode of energy optimization;

[0037] [Fig.5] The [Fig.5] is a graphical representation illustrating the difference in energy consumption between the short-circuit operating mode and the energy consumption optimization mode introduced in the process according to the invention.

[0038] Identical, similar, or analogous elements retain the same reference from one figure to another.

[0039] Fig. 1 shows different configurations of a motor vehicle traction chain 10 comprising a thermal engine 11 associated with a rotating electric machine 12 capable of operating in motor mode to provide traction for the motor vehicle and in alternator mode to recharge a battery of the on-board network, in particular during a regenerative braking phase.

[0040] In a so-called "PO" type configuration, the electric machine 12 is mechanically connected to the internal combustion engine 11 via an accessory belt which also drives other auxiliary components of the internal combustion engine, such as a water pump or an air conditioning compressor

[0041] In a so-called "PI" type configuration, the electric machine 12 is mechanically connected to the heat engine 11 on the crankshaft 13 side.

[0042] In a so-called "P2" type configuration, the electric machine 12 is arranged downstream of a clutch 15 so that it can be decoupled from the internal combustion engine 11 in a purely electric driving mode. The electric machine 12 may or may not be integrated into a gearbox 16.

[0043] In a so-called "P3" type configuration, the electric machine 12 is mechanically decoupled from the heat engine 11. The electric machine 12 has a rotational speed that is a multiple of that of the heat engine 11.

[0044] In a so-called "P4" type configuration, the electric machine 12 can be mounted on the front wheel assembly 17.1 or the rear wheel assembly 17.2 of the motor vehicle. Mounting can be achieved by means of a coupling device 18, for example a dog clutch device, capable of selectively coupling or uncoupling the electric machine with respect to the vehicle's wheels.

[0045] As can be seen in [Fig. 2], an inverter 20 is connected to phases of a permanent magnet rotor electric machine 12. The inverter 20 comprises a plurality of switching arms 21.1, 21.2, 21.3 electrically connected in parallel. Each switching arm 21.1, 21.2, 21.3 comprises an upper-side switch 22 and a lower-side switch 23 connected to each other at a midpoint, each midpoint being intended to be connected to at least one phase u, v, w of an electric machine 12. In the example of [Fig. 2], the electric machine has three phases u, v, w (and three corresponding bridge arms). Alternatively, the electric machine 12 could have any number of phases, in particular 5 phases for a five-phase configuration or 6 phases for a six-phase or double three-phase configuration.

[0046] A control module for the electric machine 12 controls the opening or closing of each switch 22, 23 to control the power supply to the electric machine 12. The bottom-side switches 23 or the top-side switches 22 are electronic power supply switches, for example, of the metal-oxide-semiconductor field-effect transistor (MOSFET) type. The intrinsic diode 25 of such a transistor has the characteristic of being current-biased.

[0047] The switches 22, 23 allow the phases u, v, w of the stator to be powered either in motor mode from a battery 26 supplying electrical power to the vehicle's on-board electrical system, or in alternator mode to supply the on-board electrical system and recharge the vehicle's battery 26. In the case of an electric machine 12 comprising three phases in the stator, the inverter 20 comprises three switches on the lower side 23, each connected to one of the three phases u, v, w and to ground, and three switches on the upper side 22, each connected to one of the three phases u, v, w and to a positive terminal of the battery 26 of the vehicle's on-board electrical system.

[0048] During certain phases of the vehicle's life cycle, the electric machine 12 is required to be at rest in a "passive" state, also known as the "idle" state. This "passive" state is implemented when the powertrain monitoring computer 10 decides not to supply power to the electrical grid or not to draw mechanical power, or in the event of a fault in the electric machine 12.

[0049] As illustrated in [Fig. 3], when the electric machine 12 is in its passive state, it is driven in open-circuit mode (OC), in which the electronic switches 22, 23 of the inverter 20 are open. The electric machine 12 is driven in open-circuit mode (OC) until a first switching criterion, Crit_l, is met. This first switching criterion, Crit_l, is either a rotational speed criterion for the electric machine 12 or an electromotive force criterion for the electromotive force generated by the electric machine 12. The speed criterion is defined, for example, by a rotational speed of the electric machine 12 between 3000 and 5000 rpm. Alternatively, the switching criterion, Crit_l, is defined by an electromotive force, for example, between 20 and 50 volts.

[0050] When the first switching criterion Crit_l is met, the electric machine 12 is driven in an intermediate energy optimization mode INT in which the overall energy consumption of the traction chain 10 is reduced compared to In ASC short-circuit mode, also called ASC mode (for Active Short Circuit), all switches 22 and 23 are closed. The overall energy consumption of the traction chain 10 is the total energy consumed by the traction chain 10 during operation, corresponding to the sum of the mechanical energy consumed by the internal combustion engine 11 and the electrical energy consumed by the electric machine 12.

[0051] As explained in more detail below, in the intermediate energy optimization mode INT, the electric machine 12 can be controlled by torque regulation to a value substantially zero in order to compensate for parasitic torque generated on the shaft of the electric machine 12 due to rotation of the permanent magnet rotor. By "substantially zero torque value," we mean a torque value of zero or in any case less than a few Newton-meters, in particular less than 1 Nm or 2 Nm.

[0052] Alternatively, the electric machine 12 is controlled by voltage regulation at a reference value that is preferably substantially equal to the voltage value of the vehicle's on-board electrical system. "Voltage substantially equal to the on-board electrical system voltage" means a voltage equal to the on-board electrical system voltage or a voltage differing by only a few volts, in particular 1 to 2 volts, from the on-board electrical system voltage. The on-board electrical system voltage depends on the vehicle and may be between 24 volts and 56 volts, and in particular 48 volts.

[0053] Alternatively, in the intermediate energy optimization mode INT, the electric machine 12 is controlled by a current regulator at a reference current value drawn by the electric machine 12 from the vehicle's on-board network. Preferably, the reference value is a current substantially zero. By "current substantially zero" is meant a current of zero or in any case less than a few amperes, in particular less than 1 ampere or 2 amperes.

[0054] The electric machine 12 is controlled in the intermediate energy optimization mode INT until a second switching criterion Crit_2 is met. This second switching criterion Crit_2 depends on the chosen control method for the electric machine 12.

[0055] In the case of torque control of the electric machine 12, the second switching criterion Crit_2 is a current consumption criterion for the electric machine 12 (and therefore a current consumption criterion drawn from the vehicle's on-board network). This current consumption criterion is defined, for example, by a current between 30A and 100A, and preferably in the order of 50A. "In the order of" means a variation of plus or minus 10% from the stated value.

[0056] In the case of voltage control of the electric machine 12 at a voltage value substantially equal to the on-board network voltage or current control of the electric machine 12 at a current value substantially zero, the second switching criterion Crit_2 is a torque criterion of the electric machine 12. This torque criterion is, for example, defined by a torque on the order of plus or minus 3 N.m. This torque value has the advantage of having a low impact on the fuel consumption of the internal combustion engine 11 and of not disrupting driving pleasure.

[0057] When the second switching criterion Crit_2 is met, the electric machine 12 is driven in the ASC short-circuit mode in which all the electronic switches 22, 23 of the inverter 20 are in the closed state.

[0058] Fig. 4a shows a functional diagram of the control of the electric machine 12 by a torque regulation at a torque substantially zero.

[0059] An electrical machine management module Ml allows setting, from the setpoint torque C* (here equal to 0), setpoint currents Id*, Iq* in the Park frame.

[0060] A current control module M2 defines corresponding setpoint voltages Vd*, Vq* in the Park reference frame.

[0061] A voltage modulation module M3 defines RC duty cycles of phase voltage sent to the inverter 20, which is electrically connected to the battery 26 of the onboard network. The inverter 20 then controls the rotating electric machine 12 in motor mode.

[0062] A current sensor allows the actual current values ​​Id, Iq to be returned to the current control module which can adapt the setpoint voltages Vd*, Vq* accordingly.

[0063] A system 28 for monitoring the position of the rotor of the electric machine 12 makes it possible to determine a position Pr and a rotational speed Wr of the rotor. These values ​​Pr and Wr are communicated to the control module of the electric machine 12. The monitoring system 28 may include, in particular, a Hall effect sensor or any other equivalent sensor suitable for the application.

[0064] Figure 4b shows a functional diagram of the control of the electric machine 12 by voltage regulation at a voltage substantially equal to the voltage of the vehicle's on-board network. Compared to the diagram in Figure 4a, a voltage regulation module 29 is introduced which compares the setpoint voltage Vdc* corresponding to the optimal operating voltage of the on-board network with the actual voltage Vdc of the on-board network and determines a corresponding torque setpoint C*.

[0065] Figure 4c shows a functional diagram of the control of the electric machine 12 by current regulation at a substantially zero current. Compared to the Diagram of [Fig.4a], we introduce a current regulation module 30 which compares the setpoint current Idc* (in our case practically zero) with the actual current delivered Idc by the on-board network and determines a corresponding torque setpoint C*.

[0066] Figure 5 shows that when the electric machine 12 is in a passive state, the electrical power P consumed by the electric machine 12 in the intermediate mode INT based on zero-torque regulation (see curve C1) is less than the mechanical power P consumed by the heat engine 11 when the electric machine 12 operates in the short-circuit mode ASC (see curve C2). This reduction in energy consumption is observable throughout the entire operating range Wr of the electric machine 12.

[0067] Of course, the different features, variants and / or embodiments of the present invention can be combined with each other in various ways insofar as they are not incompatible or mutually exclusive.

[0068] Furthermore, the invention is not limited to the embodiments described above and provided solely by way of example. It encompasses various modifications, alternative forms, and other variants that a person skilled in the art may consider within the scope of the present invention, and in particular all combinations of the different modes of operation described above, which may be taken separately or in combination.

Claims

Claims

1. Method for controlling a rotating electrical machine (12) integrated in a hybrid powertrain (10) of a motor vehicle, said rotating electrical machine (12) comprising a permanent magnet rotor and a plurality of phases (u, v, w) electrically connected to an inverter (20) provided for each phase with a switching arm (21.1, 21.2, 21.3) having a high-side electronic switch (22) and a low-side electronic switch (23), - said method comprising, when the rotating electrical machine (12) is in a passive state: - a step of controlling the rotating electrical machine (12) in an open-circuit mode (OC) in which the electronic switches of the inverter (20) are open, and - a step of controlling the electric machine (12) in a short-circuit mode (ASC) in which the electronic switches of the inverter (20) are in the closed state,characterized in that said method further comprises a step of controlling the electric machine (12) in an intermediate energy optimization mode (INT) in which an overall energy consumption of the traction chain (10) is reduced compared to the short-circuit mode (ASC), - a change from the open circuit mode (OC) to the intermediate energy optimization mode (INT) occurring when a first switching criterion (Crit_l) is met, and a change from the intermediate torque compensation mode to the short-circuit mode (ASC) occurring when a second switching criterion (Crit_2) is met and in that the first switching criterion (Crit_l) is a criterion of rotation speed of the rotating electric machine (12) or a criterion of electromotive force generated by the rotating electric machine (12).,

2. Method according to claim 1, characterized in that, in the intermediate energy optimization mode (INT), the rotating electrical machine (12) is controlled by a torque regulation at a substantially zero value so as to compensate for a parasitic torque generated on the shaft of the electrical machine (12) due to a rotation of the permanent magnet rotor.

3. Method according to claim 2, characterized in that the second switching criterion (Crit_2) is a consumption criterion of current of the rotating electrical machine (12).

4. Method according to claim 1, characterized in that, in the intermediate energy optimization mode (INT), the rotating electrical machine (12) is controlled by voltage regulation to a reference value.

5. Method according to claim 4, characterized in that the reference value is substantially equal to a voltage value of an on-board network of the motor vehicle.

6. Method according to claim 4 or 5, characterized in that the second switching criterion (Crit_2) is a torque criterion of the rotating electrical machine (12).

7. Method according to claim 1, characterized in that, in the intermediate energy optimization mode (INT), the rotating electrical machine (12) is controlled by current regulation to a reference value of current drawn by the rotating electrical machine (12).

8. Method according to claim 7, characterized in that the current reference value is a substantially zero current.

9. Method according to claim 7 or 8, characterized in that the second switching criterion (Crit_2) is a torque criterion.

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