TRAINING DEVICE COMPRISING TWO ROTATING MACHINES
A drive device with two rotating machines and coordinated control signals addresses torque drops in electric vehicles, improving robustness and safety by reducing torque fluctuations.
Patent Information
- Application Number
- FR2023013908
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-12-11
- Publication Date
- 2025-12-26
- Estimated Expiration
- 2043-12-11
AI Technical Summary
Existing drive systems in electric vehicles experience a significant torque drop during transitions between control commands, causing driver discomfort due to unexpected mechanical torque decreases.
A drive device utilizing two rotating machines with distinct transition speeds and control signals, such as pulse-width modulation and full-wave signals, to smooth torque drops by coordinating the operation of the machines to maintain consistent torque output.
The system reduces torque drops by approximately 30%, enhancing robustness and safety by ensuring redundancy and minimizing user discomfort through coordinated control of the rotating machines.
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Abstract
Description
Title of the invention: DRIVE DEVICE COMPRISING TWO ROTATING MACHINES technical field
[0001] The present invention relates to the technical field of electric vehicles.
[0002] More particularly, the invention relates to the technical field of wheel drive devices of such electric vehicles. STATE OF THE ART
[0003] It is known from the prior art a vehicle comprising a drive device in which a first rotating machine is configured to drive in rotation a transmission shaft fixed to the wheels of said vehicle.
[0004] Such a vehicle also includes a control module configured to transmit a speed command to the first rotating machine, thereby optimizing the operation of the drive system by controlling the rotational speed of the rotating machine for a predetermined transmission ratio. Such a command takes the form of a signal, for example, a pulse-width modulated signal or a full-wave signal, and the same rotating machine can be controlled by means of several signals depending on the desired rotational speed.
[0005] Such a rotating machine then exhibits a speed or speed range known as a transition speed, during which the control of the rotating machine changes from a first command to a second command, in other words, from a first signal to a second signal. During this transition, a "torque drop" phenomenon may be observed, corresponding to a significant decrease in the mechanical torque available to the vehicle, which can cause discomfort for the driver who perceives this unexpected torque drop. The phenomenon is identical in the case of a vehicle comprising a drive system with two rotating machines.
[0006] The invention aims to remedy all or part of the disadvantages of the prior art by proposing a drive device controlled by at least two controls, the torque drop of which is substantially reduced regardless of the transition speed of the rotating machine of such a device. PRESENTATION OF THE INVENTION
[0007] More specifically, the invention relates to a mechanical drive device configured to drive in rotation a transmission element comprising: • a first rotating machine connected to the transmission element according to a first transmission ratio, the first rotating machine having a first predetermined transition speed; • a second rotating machine connected to the transmission element according to a second transmission ratio, the second rotating machine having a second predetermined transition speed distinct from the first transition speed; • a control module configured to transmit a speed command from a first command and a second command to the first machine and the second machine, the transition from one command to the other command transmitted to the first rotating machine being a function of the first transition speed and the transition from one command to the other command transmitted to the second rotating machine being a function of the second transition speed.
[0008] Thanks to such a combination of features, such a drive device equipped with two rotating machines having distinct predetermined transition speeds makes it possible to smooth out a drop in mechanical torque resulting from the mechanical torque generated by the first rotating machine and the mechanical torque generated by the second rotating machine. Indeed, when the first rotating machine switches from one command to the other, causing a drop in torque in the first rotating machine, the second rotating machine does not experience a drop in torque, so the resulting torque is smoothed. The term "torque drop" refers to any decrease in mechanical torque of up to 40% observed during the transition time from one command to the other.Similarly, when the second rotating machine switches from one control to the other, causing a drop in torque, the first rotating machine does not experience a drop in torque, so the resulting torque is also smoothed. The term "smoothed" refers to a significant attenuation of the torque drop, notably reducing the discomfort caused by the torque drop for a user of a vehicle equipped with such a drive system. It has been demonstrated that such a drive system can reduce the resulting torque drop by approximately 30%.
[0009] One advantage of the invention is to improve robustness and safety by providing redundancy of rotating machines.
[0010] Advantageously, in which the first transmission ratio is distinct from the second transmission ratio. In such a configuration, the two rotating machines can, for example, transmit the same torque, each machine rotating at a different rotational speed.
[0011] Advantageously, the second transmission ratio is the result of the product between the first transmission ratio and a transmission coefficient less than 0.6.
[0012] Advantageously, the first transition speed is the product of the second transition speed and a speed coefficient less than 0.6. In such a configuration, it is guaranteed that the transition speeds of the machines are distinct. Furthermore, such dimensioning makes it possible, for example, to align the second transition speed of the second rotating machine with an ideal operating point of the first rotating machine at which the torque generated by the first machine is stable, so as to further mitigate the torque drop.
[0013] Advantageously, the first control signal is a pulse-width modulated signal and the second control signal is a full-wave signal. Pulse-width modulation is commonly referred to in English as "Pulse Width Modulation (PWM)" by those skilled in the art. A full-wave signal is commonly referred to in English as "Full Wave" by those skilled in the art.
[0014] Advantageously, the control module is configured to transmit the first command to the first rotating machine in the case where the first rotating machine rotates at a speed lower than the first transition speed and configured to transmit the second command to the first rotating machine in the case where the first rotating machine rotates at a speed higher than the first transition speed.
[0015] Advantageously, the control module is configured to transmit the second command to the second rotating machine in the case where the second rotating machine rotates at a speed lower than the second transition speed and configured to transmit the second rotating machine to the second rotating machine in the case where the second rotating machine rotates at a speed higher than the first transition speed.
[0016] Advantageously, the first rotating machine and the second rotating machine are electric motors.
[0017] Advantageously, in which the control module is an inverter connected to phases of the first rotating machine and to phases of the second rotating machine.
[0018] According to another aspect of the invention, it relates to a mobility device comprising a drive device as described above. PRESENTATION OF FIGURES
[0019] The invention will be better understood upon reading the following description, given solely by way of example, and referring to the accompanying drawings given by way of non-limiting examples, in which identical references are given to similar objects and on which:
[0020] Fig. 1 is a schematic representation of a drive device according to one embodiment of the invention;
[0021] Fig. 2 is a graph illustrating characteristic speed-torque curves of a first rotating machine of the drive device, of a second rotating machine of the drive device, and of the drive device of Fig. 1.
[0022] It should be noted that the figures set out the invention in detail to enable implementation of the invention; although not limiting, said figures serve in particular to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION
[0023] The invention relates to a drive device 2, in particular configured to drive a transmission element 4 in rotation, for example a differential driving the wheels of a vehicle 1, as illustrated in [Fig. 1]. The drive device 2 comprises a first rotating machine 6 connected to the transmission element 4. The first rotating machine 6 is configured to generate a first mechanical torque Cl and transmit this first mechanical torque Cl to the transmission element 4 according to a first transmission ratio.
[0024] The drive device 2 comprises a second rotating machine 8 connected to the transmission element 4. The second rotating machine 8 is configured to generate a second mechanical torque C2 and transmit this second mechanical torque C2 to the transmission element 4 according to a second transmission ratio. Advantageously, the first transmission ratio is distinct from the second transmission ratio. In such a configuration, the two rotating machines can, for example, transmit the same mechanical torque C1, C2 even though each rotating machine 6, 8 rotates at a different speed.
[0025] The drive device 2 thus transmits to the transmission element 4 a mechanical torque C3 resulting from the first mechanical torque and the second mechanical torque.
[0026] In the embodiment described in [Fig. 1], the vehicle 1 may, in particular, be an electric or hybrid vehicle. In such a configuration, the first rotating machine 6 and the second rotating machine 8 are advantageously electric motors.
[0027] To be operated by a user, the drive device 2 includes a control module 10. The control module is configured to transmit a speed command to the first rotating machine 6 and to the second rotating machine 8. In the embodiment described in [Fig. 1], the control module 10 is preferably a voltage converter such as an inverter, connected to phases of the first rotating machine 6 and to phases of the second rotating machine 8.
[0028] The speed command is selected from a first command and a second command. The speed command transmitted to each rotating machine is a function of a transition speed of the machine in question. Thus, the first rotating machine 6 has a first transition speed QL. Similarly, the second rotating machine 8 has a second transition speed Q2. The transition from one command to the other transmitted to the first rotating machine 6 is then a function of the first transition speed QL. The transition from one command to the other transmitted to the second rotating machine 8 is then a function of the second transition speed Q2. The two transition speeds QL and Q2 are distinct.
[0029] Advantageously, the first transition speed Q1 is the product of the second transition speed Q2 and a speed coefficient less than 0.6. In such a configuration, it is guaranteed that the transition speeds Q1 and Q2 of the rotating machines 6 and 8 are distinct. Furthermore, such dimensioning makes it possible, for example, to align the second transition speed Q2 of the second rotating machine 8 with an ideal operating point of the first rotating machine 6, at which the first mechanical torque Cl generated by the first machine 6 is stable, thus further mitigating the torque drop.
[0030] The switch from one control to the other control can advantageously be carried out precisely when the rotating machine 6,8 reaches exactly the transition speed Q1, Q2. Alternatively, the switch from one control to the other control can be carried out when the rotational speed of the rotating machine 6,8 is within a range where the transition speed Q1, Q2, for example, is between 0.95 times the transition speed and 1.05 times the transition speed Q1, Q2.
[0031] Fig. 2 illustrates characteristic speed-torque curves representing the evolution of the first mechanical torque Cl, the second mechanical torque C2 and the resulting torque C3 as a function of the rotational speed of the first rotating machine 6 and the second rotating machine 8.
[0032] When the first rotating machine 6 passes from one control to the other control, a drop in the first mechanical torque Cl of the first rotating machine 6 is observed, for a rotation speed equal to the transition speed QL. In the same way, when the second rotating machine 8 passes from one control to the other control, a drop in the second mechanical torque C2 of the second rotating machine 8 is observed, for a rotation speed equal to the transition speed Q2.
[0033] The drive device 2 thus advantageously smooths the torque drop observed respectively on the characteristic curve of the first torque mechanical Cl and the characteristic curve of the second mechanical couple C2. Indeed, by combining the first rotating machine 6 and the second rotating machine 8 on the same transmission element, the characteristic curve of the resulting torque C3 is smoothed, that is to say that the observed torque drops are attenuated, on the order of about 40%.
[0034] Thus, the discomfort generated by the drop in torque for a user of the vehicle 1 including such a drive device 2 is substantially reduced.
[0035] The curves in [Fig. 2] illustrate an embodiment in which the first control signal is, in particular, a pulse-width modulated signal and the second control signal is a full-wave signal. Pulse-width modulation is commonly referred to in English as "Pulse Width Modulation (PWM)" by those skilled in the art. Full-wave is commonly referred to in English as "Full Wave" by those skilled in the art.
[0036] The control module 10 is then configured to transmit the first command to the first rotating machine 6 if the first rotating machine 6 is rotating at a speed lower than the first transition speed QL. The control module 10 is also configured to transmit the second command to the first rotating machine 6 if the first rotating machine 6 is rotating at a speed higher than the first transition speed QL.
[0037] Furthermore, the control module 10 is configured to transmit the second command to the second rotating machine 8 if the second rotating machine 8 is rotating at a speed lower than the second transition speed Q2. The control module 10 is also configured to transmit the second command to the second rotating machine 8 if the second rotating machine is rotating at a speed higher than the first transition speed QL.
[0038] It should also be noted that the invention is not limited to the embodiments described above. It will indeed be apparent to a person skilled in the art that various modifications can be made to the embodiment described above, in light of the information just disclosed to them.
[0039] In the detailed presentation of the invention given above, the terms used shall not be interpreted as limiting the invention to the embodiment set forth in this description, but shall be interpreted to include all equivalents which can be foreseen by a person skilled in the art by applying their general knowledge to the implementation of the teaching which has just been disclosed to them.
Claims
Demands
1. Mechanical drive device (2) configured to drive in rotation a transmission element (4) comprising: • a first rotating machine (6) connected to the transmission element (4) according to a first transmission ratio, the first rotating machine (4) having a first predetermined transition speed (Q1); • a second rotating machine (8) connected to the transmission element (4) according to a second transmission ratio, the second rotating machine (8) having a second predetermined transition speed (Q2) distinct from the first transition speed (Q1);• a control module (10) configured to transmit a speed command from a first command and a second command to the first machine (6) and to the second machine (8), the transition from one command to the other command transmitted to the first rotating machine (6) being a function of the first transition speed (Q1) and the transition from one command to the other command transmitted to the second rotating machine (8) being a function of the second transition speed (Q2).
2. Drive device (2) according to claim 1, wherein the first transmission ratio is distinct from the second transmission ratio.
3. Drive device (2) according to claim 2, wherein the second transmission ratio is the result of the product between the first transmission ratio and a transmission coefficient less than 0.
6.
4. A drive device (2) according to any one of the preceding claims, wherein the first transition speed (Q1) is the result of the product between the second transition speed (Q2) and a speed coefficient less than 0.
6.
5. A drive device (2) according to any one of the preceding claims, wherein the first control is a pulse-width modulated signal and the second control is a signal full wave.
6. Drive device (2) according to claim 5, wherein the control module (10) is configured to transmit to the first rotating machine (6) the first command in the case where the first rotating machine (6) rotates at a speed lower than the first transition speed (Ql) and configured to transmit to the first rotating machine (6) the second command in the case where the first rotating machine (6) rotates at a speed higher than the first transition speed (Ql).
7. Drive device (2) according to claim 5 or 6, wherein the control module (10) is configured to transmit to the second rotating machine (8) the second command in the case where the second rotating machine (8) rotates at a speed lower than the second transition speed (Q2) and configured to transmit to the second rotating machine (8) the second command in the case where the second rotating machine (8) rotates at a speed greater than the second transition speed (Q2).
8. Drive device (2) according to any one of the preceding claims, wherein the first rotating machine (6) and the second rotating machine (8) are electric motors.
9. Drive device (2) according to claim 8, wherein the control module (10) is an inverter connected to phases of the first rotating machine (6) and to phases of the second rotating machine (8).
10. Electric or hybrid vehicle (1), comprising a drive device (2) according to any one of claims 1 to 9.