FR3043285B1 - METHOD AND DEVICE FOR CONTROLLING A ROTARY ELECTRIC MACHINE OF A MOTOR VEHICLE, AND CORRESPONDING MACHINE - Google Patents

Abstract

The rotating electrical machine is of the type of two-voltage and multi-phase (15) and comprises a rotor mechanically coupled (9) to a heat engine (10) of the vehicle, a stator having first star phase windings connected to a first inverter connected to a first sub-network (2) of a vehicle power supply network (16) at a first nominal DC voltage, and second phase windings connected to a second reversible inverter connected to a second sub-network. network (5) of the electrical network at a second nominal DC voltage, less than the first nominal DC voltage, and a transfer circuit electrically connecting a neutral point of the first windings to the second sub-array. According to the invention, the method, in a mode of operation of the machine at the stop in DC-DC converter, provides control of the first inverter in pulse width modulation as a function of a power supplied to the second subnet according to a predetermined driving strategy.

Description

METHOD AND DEVICE FOR CONTROLLING A ROTATING ELECTRIC MACHINE OF A MOTOR VEHICLE,

AND CORRESPONDING MACHINE TECHNICAL FIELD OF THE INVENTION The invention relates to a method and a device for controlling a rotating electric machine of a motor vehicle, and to such a machine comprising this device. BACKGROUND ART OF THE INVENTION.

Motor vehicles with a combustion engine conventionally comprise an on-board electrical network comprising a battery, generally 12 V, intended to supply electrical energy to various equipment, in particular a starter, which is essential for starting the engine. After starting, an alternator coupled to the engine ensures the charging of the battery.

Nowadays, the development of power electronics allows to power and control a single reversible polyphase rotating electric machine which advantageously replaces the starter and the alternator.

Initially, this machine, known as alternator-starter, was primarily intended to perform the functions formerly dedicated to the alternator and the starter, and, secondarily, to recover the energy when braking, or d 'bring extra power and torque to the engine.

In order to increase the power and improve the efficiency of the alternator-starter by increasing its operating voltage while maintaining the possibility of using other standard equipment, provided for a power supply of 12 V to 14 V, including lead batteries, was developed a bi-voltage architecture.

This architecture consists of an electrical power network connecting the starter-alternator to an electrical energy storage element operating at a voltage greater than 14 V, up to 48 V, and a 12 V service electrical network connecting all other equipment. The adaptation of the voltage levels between the two networks is ensured by a reversible DC-DC converter, generally with a power of between 1.5 kW and 3 kW.

In this context, the structure of the reversible DC-DC converter is chosen to maximize the efficiency (95% for example) at a reasonable cost, but this converter must be integrated into the vehicle (housing about 25 cm by 20 cm out of 8 cm), must also be cooled, and represents an additional cost per se.

Therefore, in order to simplify the structure of the vehicle, it is known to use, in a two-voltage network architecture, a specific dual-voltage electrical rotating machine capable of performing DC-DC conversion to supply the 12 V loads.

This electrical machine is generally a two-three-phase machine in which are incorporated a first reversible inverter connected to a first high voltage network (48 V) and a second reversible inverter connected to a second low voltage network (12 V).

A machine of this type is described in particular in the US patent application US2014 / 0375232.

When the machine is not running, the double phase windings of a stator act as a transformer as in a conventional DC-DC converter.

But the phase windings of this type of machine have a very low inductance compared to that found in a suitable DC-DC converter, and the iron losses in the stator are much higher.

This has the result that the efficiency of the conversion is quite low compared to that of a suitable converter, which represents a disadvantage, while in addition the bi-voltage architecture is simplified. GENERAL DESCRIPTION OF THE INVENTION

The present invention therefore aims to overcome this disadvantage by means of a specific method and a control device.

The control method in question relates to a rotating electric machine of a motor vehicle of the type of double-voltage reversible multi-phase comprising: - a rotor capable of being mechanically coupled to a thermal engine of the motor vehicle; a stator comprising first star phase windings connected to a first reversible inverter adapted to be connected by a first output terminal to a first sub-network of an electrical supply network for the equipment of the motor vehicle at a first voltage; predetermined nominal continuous current with respect to a reference potential of a ground terminal, and second phase windings connected to a second reversible inverter adapted to be connected by a second output terminal to a second sub-network of the electrical network; supplying at a predetermined second nominal DC voltage with respect to the reference potential lower than the first predetermined nominal DC voltage; a transfer circuit electrically connecting a neutral point of the first phase windings to the second output terminal.

In the method of the invention, in a mode of operation of the machine at the stop in DC-DC converter, the first inverter is modulated in pulse width modulation as a function of a power supplied to the second sub. -Network according to a predetermined steering strategy.

According to the invention, this control strategy comprises at least one change from a current control mode taken in a group of predetermined control modes of the first inverter to the passage of the power of a current power threshold taken in a set of predetermined power thresholds.

This group comprises, according to the invention: a first control mode in which one of the phases is piloted in discontinuous mode; a second control mode in which one of the phases is piloted in continuous mode; a third control mode in which two of the phases are piloted; a fourth control mode in which two of the phases are piloted with a first predetermined phase shift; a fifth control mode in which phase three of the phases is piloted; a sixth control mode in which three of the phases are piloted with a second predetermined phase shift.

In the first control mode, an active winding of the first phase windings of the ground terminal is disconnected, or a switch of the transfer circuit is opened when this active winding is not energized.

According to the invention, the set of predetermined power thresholds comprises a low threshold, a mean threshold, a high threshold.

Each of these power thresholds has a predetermined hysteresis range.

In the control strategy of one embodiment of the control method according to the invention, the machine being a two-three-phase machine, the current driving mode is the fifth driving mode below the average threshold and the sixth driving mode is above this average threshold.

In the control strategy of another embodiment of the control method according to the invention, the machine being also a double-three-phase machine, the current driving mode is the first driving mode below the low threshold, the second control mode above the low threshold and below the average threshold, the third control mode or the fourth control mode above the average threshold and below the high threshold, and the fifth control mode or the sixth control mode above the high threshold. The invention also relates to a device for controlling a rotating electric machine of a motor vehicle capable of carrying out the method described above.

This machine is of the type of double-voltage reversible multi-phase comprising: - a rotor adapted to be mechanically coupled to a thermal engine of the motor vehicle; a stator comprising first star phase windings connected to a first reversible inverter adapted to be connected by a first output terminal to a first sub-network of an electrical supply network for the equipment of this motor vehicle to a first predetermined nominal DC voltage relative to a reference potential of a ground terminal, and second phase windings connected to a second reversible inverter adapted to be connected by a second output terminal to a second sub-network of the electrical network; supplying at a predetermined second nominal DC voltage with respect to the reference potential lower than the first predetermined nominal DC voltage; a transfer circuit electrically connecting a neutral point of the first phase windings to the second output terminal.

According to the invention, this control device comprises: - means for storing a group of control modes of the first inverter in pulse width modulation in a mode of operation of the machine at a DC converter stop - direct current, and a set of power thresholds; means for determining a power supplied to the second sub-network; means for comparing the power supplied with respect to said power thresholds; means for selecting a current control mode from the group of control modes according to a result provided by the comparison means; - Means for controlling the first inverter by the current control mode.

According to the invention, the control device further comprises means for controlling a switch of the transfer circuit by the current control mode. The invention also relates to a reversible two-phase reversible electric motor of a motor vehicle which comprises a control device as described above.

These few essential specifications will have made obvious to those skilled in the art the advantages of the method and the control device of a rotary electric machine of a motor vehicle according to the invention, as well as a machine comprising this control device, compared to the state of the art.

The detailed specifications of the invention are given in the following description in conjunction with the accompanying drawings. It should be noted that these drawings have no other purpose than to illustrate the text of the description and do not constitute in any way a limitation of the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an electrical power supply network for the equipment of a double sub-network automobile vehicle known from the state of the art, implementing a dedicated DC-DC converter.

FIG. 2 is a block diagram of another electrical power supply network for the equipment of a double sub-network motor vehicle known from the state of the art, implementing a polyphase double-voltage rotating electrical machine of the type concerned by the invention.

Figure 3 is a detailed block diagram of a reversible double-three-phase dual-phase rotary electric machine comprising a control device according to the invention.

Figures 4, 5a and 5b are timing diagrams illustrating control modes an input inverter of the machine shown in Figure 3 by a control device according to the invention, respectively with a single phase control, with two-phase phase control, and two phase-shifted phases.

FIGS. 6a and 6b are timing diagrams illustrating conventional control modes of an input inverter of the machine shown in FIG. 3 by a control device according to the invention, respectively with a three phase phase control. , and three phases out of phase, in a mode of operation at standstill in DC-DC converter.

Figures 7a and 7b show a conversion efficiency versus a power output respectively for the conventional driving modes shown in Figures 6a and 6b, and for the driving modes illustrated in Figures 4, 5a and 5b.

Figures 8a and 8b respectively illustrate a control strategy based on the conventional control modes illustrated in Figures 6a and 6b, and another control strategy based on the control modes illustrated in Figures 4, 5a and 5b. DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The electrical power supply network 1 for the equipment of a double sub-network automobile vehicle known from the state of the art, shown in FIG. 1, comprises: a first electrical sub-network 2 operating under a first DC voltage nominal V1 of 48 V and connected to an electrical energy store 3, supplying first charges 4 under this first voltage V1; a second electrical sub-network 5 operating under a second nominal DC voltage V 2 of 12 V and connected to a battery 6 of the lead-acid type, supplying second electric charges 7.

A reversible polyphase rotating electric machine 8 is mechanically coupled to a heat engine of the vehicle 10 for supplying electric power 11 to the first sub-array 2.

A reversible DC-DC converter 12 is connected between the first and second sub-arrays 2, 5 to supply electrical energy 13 to the second conventional electrical charges 7 at 12 V, and generally to provide energy transfers 14 between the two subnets 2, 5.

As indicated in the preamble, to simplify the architecture of the vehicle, it is known to supply the two sub-networks 2, 5 with a reversible polyphase double-voltage electrical rotating machine 15 in a configuration of another network 16 shown in FIG. .

A structure of a double-three-phase double-voltage machine 15 which is the subject of the invention is shown in detail in FIG. 3.

This machine 15 comprises, in a manner known per se: a rotor 17 adapted to be mechanically coupled to the heat engine 10 of the vehicle and comprising an induction coil 18; a stator comprising first star phase windings 19 (two turns per pole) connected to a first reversible inverter 20 and second phase windings 21 connected here in a star (half a turn per pole) and connected to a second reversible inverter 22.

The first and second reversible inverters 20, 22 are formed of three-phase bridges whose arms comprise controllable semiconductor power switches connecting, on the one hand, the first and second phase windings 19, 21 respectively to first and second output terminals 23, 24 adapted to be connected to the first and second sub-networks 2, 5 (upper semiconductor switches HS 1, HS 2, HS 3, HS 4, HS 5, HS on the high-side side), and, d on the other hand, at a ground terminal (lower semiconductor switches LS1, LS2, LS3, LS4, LS5, LS6, on the so-called "low-side" side).

In this architecture 16, there is a control of the machine 15 adapted (torque management by pulse width modulation PWM1, PWM2 control of the inverters 20, 22) to perform all the functions of a hybrid electric machine (start mode, motor mode, generator mode) based on the energy supplied to, or provided by, the first and second sub-networks 2, 5 (48 V or 12 V).

A function equivalent to that of the DC-DC converter 12 (supplying energy 13 to the 12 V loads) of the conventional network 1 with an additional DC-DC converter 12 is performed when the machine 15 is in generator mode and in rotation.

To ensure this function of DC-DC converter even when the electric machine 15 is not running (thermal engine off), a transfer circuit 26 comprising a switch 27 (bidirectional, as shown in Figure 3, for an embodiment with semiconductor switches) is arranged between a neutral point 28 of the first phase windings 19 and the second output terminal 24 to the second sub-array 5 (12 V).

When the machine 15 is stopped, this switch 27 is closed and the first phase windings 19 supplied at 48 V are used as inductors of a DC-DC converter (equivalent to the primary of a 1/4 ratio transformer) of in order to allow the exchange of energy from one network to the other 2, 5 as with a conventional DC-DC converter 12.

The power switches of the first inverter 20 connected to the first sub-network (48 V) are driven in pulse width modulation PWM1, at a frequency of 10 to 20 kHz, for example, to regulate the phase current IU, IV , IW in each u, v, w of the first phase windings 19, and filtering is provided by the capacitors 29, 30 already present in the machine 15 for operation in motor mode or in generator mode.

As already noted in the preamble, the first phase windings 19 of the machine 15 have a very low inductance compared to that which can be found in a dedicated DC-DC converter 12. As a result, iron losses in a stator carcass are much higher. The inventive entity has noticed that, in a mode of operation of the machine 15 when stopped in a DC-DC converter, there were several possibilities of controlling PWM1 pulse width modulation in the first inverter 19 by supplying a power supply. or several phases u, v, w by phase voltages U, V, W, phase-shifted or otherwise, to reduce the losses ir while limiting an effective current in the input capacitors 29 of the first inverter 20.

In first and second control modes A, A 'illustrated by the timing diagram of FIG. 4, a single phase u is powered under the phase voltage U (solid line 30). Since only one phase u is fed, the iron losses due to the phase current IU (dashed line 31) are low.

These losses iron are all the lower, as in the first control mode A considered, for a very low output power P (power P supplied to the second sub-network 5 by an output current I2 under the second nominal DC voltage V2) of less than 200 or 300 W, an active phase winding u is disconnected from the ground terminal 25 when it is not powered. Alternatively, alternatively, the switch 27 of the transfer circuit 26 is open.

In third and fourth control modes B, B 'of the first inverter 20 illustrated in FIGS. 5a and 5b, two phases u, v are powered under phase voltages U, V (solid lines 32).

Since the phase currents IU, IV (dashed lines 33) can be large in the third control mode B (FIG. 5a) in which the phase voltages U, V are in phase, it is preferred to limit the rms current in the capacitors. input 29 of the first inverter 20 to use a fourth driving mode B 'of the two phases u, v illustrated in FIG. 5b, in which the two phase voltages U, V are phase shifted by 180 electrical degrees, that is to say ie, shifted half a period 1 / 2F in time (where F is a PWM1 pulse width modulation frequency).

Fifth and sixth control modes C, C ', illustrated by the time diagrams shown in FIGS. 6a and 6b implement the three phases u, v, w, as is conventionally done in the machines known in the state. of the technique.

The phase currents IU, IV, IW (dashed lines 34) can be significant when the three phase voltages U, V, W (solid lines 35) are in phase (FIG. 6a) in the fifth control mode C, the sixth control mode C '(Figure 6b) where the three phase voltages U, V, W are phase shifted by 120 "electrical, that is to say shifted by a third of 1 / 3F period is preferred.

Tests have been carried out by the inventive entity on a two-three-phase machine 15 operating at a standstill in DC-DC converter down to between 48.5 V and 13.7 V (typical use in a vehicle) with a modulation in width of pulses PWM1 at a frequency F of 16 kHz in a power range P from 0 to 3000 W.

FIGS. 7a and 7b show that a conversion efficiency r of the machine 15 varies as a function of the power supplied P and according to the first, second, fourth, fifth and sixth control modes A, A ', B', C, C 'specified above.

For the fifth and sixth control modes C, C ', a yield difference Ar of ten points for the benefit of the fifth control mode C (double dotted line and alternate dashes) with respect to the sixth control mode C' (feature in alternating dots and dashes) appears for a low power P, around 500 W (77% instead of 67%), as shown in Figure 7a.

Figure 7b also shows that: - the first driving mode A (dashed line) corresponds to an interesting performance r greater than all the other driving modes A ', B', C 'up to a power of 250 W ; the second driving mode A '(solid line) corresponds to an interesting performance r greater than modes A, B' and C 'from 250 W to 800 W; - The fourth driving mode B '(dashed line) corresponds to a r interesting performance higher mode C' from 800 W to 1500 W; the sixth control mode C '(dashed line and alternating dashes) corresponds to an interesting yield r from a power P of 1500 W.

Taking these results into account, in the control method of the motor vehicle rotating electrical machine 15 according to the invention, the first inverter 20 is modulated in pulse width modulation PWM1 as a function of a power P supplied to the second sub. network 5 according to a predetermined control strategy.

In a control strategy illustrated in FIG. 8a, the first inverter 5 is driven by the fifth control mode C up to a power threshold S of approximately 950 W, and by the sixth control mode C 'above.

A hysteresis range 36, of the order of 200 or 300 W, is implemented around P | _, Ph of the power threshold S to avoid any untimely oscillation between the two control modes C, C '.

In another control strategy illustrated in FIG. 8b, the first inverter 5 is driven more finely: by the first control mode A below a low threshold S1 of approximately 250 W; by the second driving mode A 'above this low threshold S1 and below an average threshold S2 of about 950 W; by the third control mode B or the fourth control mode B 'above this average threshold S2 and below a high threshold S3 of approximately 1500 W; the fifth control mode C or the sixth control mode C 'above this high threshold.

Hysteresis ranges 36 are also implemented around the low thresholds S1 (hysteresis range P1l, P1h), average S1 (hysteresis range P2L, P2H) and high (hysteresis range P3 | _, P3h).

The control method according to the invention is implemented in the rotating electrical machine of a motor vehicle 15 by a control device 37, comprising as well shown in FIG. 3: memory means 38 of a group of control modes A , A ', B, B', C, C 'of the first inverter PWM1 pulse width modulation in a mode of operation of the machine to stop DC converter -current DC, and a set power thresholds S, S1, S2, S3; means 39 for determining a power P supplied to the second sub-network 5 from sensors 40, 41 of the second nominal DC voltage V2 and the output current I2; - Comparison means 42 of the power P with respect to the power thresholds S, S1, S2, S3; selection means 43 for a current control mode among the group of control modes A, A ', B, B', C ', as a function of a result provided by the comparison means 42; control means 44 of the first inverter 20 by the current control mode PWM1.

For the implementation of the variant of the first control mode A of the method, the control device 37 according to the invention further comprises control means 45 of the switch of the transfer circuit 26 by the current control mode PWM1 .

The control device 37 is preferably made in the form of a microprocessor or a microcontroller whose firmware includes the instructions representative of the method according to the invention; it may be a modification of the firmware of an electronic control unit of a rotating electrical machine of an earlier motor vehicle of the type concerned by the invention.

It goes without saying that the invention is not limited to the only preferred embodiments described above.

The numerical values indicated are only examples intended to demonstrate the advantage brought about, in terms of a limitation of iron losses and an improvement in efficiency r, by the implementation of different control modes A, A ', B, B', C, C 'of the input inverter 20 of a reversible two-phase double-three-phase rotating electrical machine 15 operating at a standstill in DC-DC converter.

A similar description could be applied to machines of the same type having a greater number of phases, and supplying electricity networks 16 of double sub-network automotive vehicles 2, 5 with nominal continuous voltages V1, V2 different from those cited. The invention therefore embraces all possible variants of embodiment within the scope of the subject of the claims below.

Claims (10)

1) A method for controlling a rotating electric machine of a motor vehicle of the type of double-voltage reversible multi-phase (15) comprising a rotor (17) adapted to be mechanically coupled (9) to a heat engine (10) of said motor vehicle, a stator (19, 21) comprising first star phase windings (19) connected to a first reversible inverter (20) adapted to be connected by a first output terminal (23) to a first sub-network ( 2) an electrical power supply network (16) for supplying the equipment (3) of said motor vehicle with a predetermined first nominal voltage (V1) with respect to a reference potential of a ground terminal (25), and second phase windings (21) connected to a second reversible inverter (22) adapted to be connected by a second output terminal (24) to a second sub-network (5) of said one-second power supply network (16) continual voltage a predetermined nominal value (V2) with respect to said reference potential lower than said first predetermined nominal DC voltage (V1), a transfer circuit (26) electrically connecting a neutral point (28) of said first phase windings (19) to said second output terminal (24), characterized in that, in a mode of operation of said machine (15) at the stop in DC converter -current DC, driving said first inverter (20) in modulation width of d pulses (PWM1) as a function of a power (P) supplied to said second sub-network (5) according to a predetermined driving strategy, said determined driving strategy comprising at least one change of a current driving mode taken in a group of predetermined driving modes (A, A ', B, B', C, C ') of said first inverter (20) at the passage of said power (P) from a current power threshold taken in a set of thresholds of predicted power terminated (S; S1, S2, S3), said group (A, A ', B, B', C, C ') of predetermined control modes comprising: - a first control mode (A) in which one pilot (u) said phases (u, v, w) in discontinuous mode; a second driving mode (A ') in which one (u) of said phases (u, v, w) is driven in continuous mode; a third control mode (B) in which two phases (u, v, w) are piloted in phase two (u, v); a fourth control mode (B1) in which two (u, v) of said phases (u, v, w) are piloted with a first predetermined phase shift; a fifth control mode (C) in which three phases (u, v, w) of said phases (u, v, w) are piloted; a sixth control mode (C1) in which three (u, v, w) of said phases (u, v, w) are piloted with a second predetermined phase shift. 2. A method of controlling a rotating motor vehicle electrical machine (15) according to claim 1, characterized in that in said first driving mode (A) an active winding (u) of said first phase windings (19) is disconnected. ) of said ground terminal (25), or a switch (27) of said transfer circuit (26) is opened when said active winding (u) is not energized. 3) A method of controlling a motor vehicle rotating electrical machine (15) according to claim 2, characterized in that said set (S, S1, S2, S3) comprises a low threshold (S1), a mean threshold ( S2), a high threshold (S3). 4) A method of controlling a motor vehicle rotating electrical machine (35) according to claim 3, characterized in that each of said power thresholds (S, S1, S2, S3) has a predetermined hysteresis range (36). ). 5) A method of controlling a rotary electric machine of a motor vehicle (15) according to claim 4, characterized in that in said driving strategy, said machine (15) being a two-three-phase machine, said current steering mode is said fifth control mode (C) below said average threshold (S2) and said sixth control mode (C ') above said average threshold (S2). 6) A method of controlling a rotating motor vehicle electrical machine (15) according to claim 5, characterized in that in said driving strategy, said machine (15) being a two-three-phase machine, said current steering mode is said first control mode (A) below said low threshold (S1), said second control mode (A ') above said low threshold (S1) and below said average threshold (S2), said third control mode (B) or said fourth control mode (B ') above said average threshold (S2) and below said high threshold (S3), and said fifth control mode (C) or said sixth control mode (C') above said upper threshold (S3). 7) A method of controlling a rotary electric machine of a motor vehicle (15) according to any one of claims 5 or 6, characterized in that - said first and second phase-shifts are respectively 180 and 120 electrical degrees; said low threshold (S1), average threshold (S2) and high threshold (S3) are respectively substantially 250 W, 950 W and 1500 W. - said hysteresis range (26) is of the order of 100 W or 200 W. 8) Control device (37) for a rotating motor vehicle electrical machine (15) suitable for carrying out the method according to any one of the preceding claims 1 to 7, said machine (15) being of the type of those reversible multi-phase double voltage comprising a rotor (17) mechanically coupled (9) to a heat engine (10) of said motor vehicle, a stator (19, 21) having first connected star phase windings (19) a first reversible inverter (20) adapted to be connected by a first output terminal (23) to a first sub-network (2) of an electrical network (16) supplying the equipment (3) of said motor vehicle to a first nominal DC voltage (V1) predetermined with respect to a reference potential of a ground terminal (25), and second phase windings (21) connected to a second reversible inverter (22) adapted to be connected by a second bound outputting (24) to a second subarray (5) of said power supply network (16) at a second nominal DC voltage (V2) predetermined with respect to said reference potential lower than said predetermined first predetermined DC voltage (V1) a transfer circuit (26) electrically connecting a neutral point (28) of said first phase windings (19) to said second output terminal (24), characterized in that it comprises: - memory means (38) a group of control modes (A, A ', B, B', C, C ') of said first pulse width modulated (PWM1) inverter (20) in an operating mode of said machine (15). ) stopping in DC-DC converter, and a set of power thresholds (S; S1, S2, S3); means for determining (39, 40, 41) a power (P) supplied to said second sub-network (5); means for comparing (42) said power (P) with respect to said power thresholds (S; S1, S2, S3); selection means (43) for a current control mode from among said group of control modes (A, A ', B, B', C, C ') as a function of a result provided by said comparison means (43); - Control means (44) of said first inverter (20) by said current control mode. 9) Control device of a motor vehicle rotating electrical machine (15) according to claim 8, characterized in that it further comprises control means (45) of a switch (27) of said transfer circuit (26) by said current steering mode. 10) Reversible multi-phase reversible dual voltage electrical machine for a motor vehicle (15), characterized in that it comprises a control device (37) according to any one of the preceding claims 8 or 9.