Drive device comprising two rotating machines
The drive device for electric vehicles, featuring two rotating machines with distinct transition speeds and command-based control, addresses the torque drop issue, resulting in reduced discomfort and maintained torque availability for the driver.
Patent Information
- Application Number
- JP2024215264
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-12-11
- Filing Date
- 2024-12-10
- Publication Date
- 2025-06-23
AI Technical Summary
Existing electric vehicle drive devices experience a significant torque drop during transitions between speed commands, leading to discomfort for the driver and reduced mechanical torque availability.
A drive device with two rotating machines, each with a different predetermined transition speed, is controlled by a module that transitions between two commands based on the specific transition speed of each machine, thereby smoothing the torque reduction.
The solution effectively reduces torque reduction by approximately 30%, enhancing driver comfort and maintaining mechanical torque availability during transitions.
Smart Images
Figure 2025093313000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of electric vehicles.
[0002] More specifically, the present invention relates to the technical field of devices for driving the wheels of such electric vehicles.
Background Art
[0003] From the prior art, there is known a vehicle provided with a drive device, in which a first rotating machine is configured to rotationally drive a transmission shaft integrally with the wheels of the vehicle.
[0004] Such a vehicle further includes a control module configured to transmit a speed command to the first rotating machine. Thereby, by controlling the rotational speed of the rotating machine with respect to a predetermined transmission ratio, the operation of the drive device can be optimized. Such a command takes the form of a signal such as, for example, a pulse width modulation signal or a full-wave signal. The same rotating machine can be controlled via a plurality of signals as a function of the rotational speed at which it is desired to rotate the rotating machine.
[0005] Such a rotating machine has a speed or speed range called a transition speed or transition speed range. In the speed or speed range, the command of the rotating machine transitions 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. This torque drop phenomenon corresponds to a significant reduction in the mechanical torque available for use in the vehicle and can be a hindrance to the driver who senses this unexpected torque drop. This phenomenon is the same in the case of a vehicle provided with two rotating machines.
[0006] The present invention aims to improve all or part of the drawbacks of the prior art by proposing a drive device controlled by at least two commands, in which torque drop is substantially reduced regardless of the transition speed of the rotating machine of such a device.
Summary of the Invention
[0007] More specifically, the present invention relates to a mechanical drive device configured to rotationally drive a transmission element, - 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 different from the first transition speed; - a control module configured to transmit a speed command of either a first command or a second command to the first machine and the second machine, wherein a transition from one command transmitted to the first rotating machine to the other command is a function of the first transition speed, and a transition from one command transmitted to the second rotating machine to the other command is a function of the second transition speed; and relates to a drive device comprising the same.
[0008] With such a combination of features, such a drive device provided with two rotating machines having different predetermined transition speeds can smooth the reduction in mechanical torque resulting from the mechanical torque generated by the first rotating machine and the second mechanical torque generated by the second rotating machine. Specifically, even when the first rotating machine transitions from one command to the other and a torque reduction occurs in the first rotating machine, no torque reduction occurs in the second rotating machine, so the resulting torque is smoothed. The term "torque reduction" is understood to mean any reduction in mechanical torque up to a maximum of 40% observed during the transition from one command to the other. Similarly, even when the second rotating machine transitions from one command to the other and a torque reduction occurs in the second rotating machine, no torque reduction occurs in the first rotating machine, so the resulting torque is likewise smoothed. The term "smoothed" is understood to mean that by significantly reducing the torque reduction, the discomfort caused by the torque reduction felt by the user of a vehicle equipped with such a drive device can be particularly reduced. It has been experimentally confirmed that such a drive device can reduce the resulting torque reduction by approximately 30%.
[0009] An advantage of the present invention is that by providing redundancy in the rotating machines, robustness and safety are improved.
[0010] Advantageously, the first transmission ratio is different from the second transmission ratio. In such a configuration, the two rotating machines can transmit the same torque while rotating at different rotational speeds, for example.
[0011] Advantageously, the second transmission ratio is the result of the product of the first transmission ratio and a transmission coefficient less than 0.6.
[0012] Advantageously, the first transition speed is the result of the product of the second transition speed and a speed coefficient less than 0.6. In such a configuration, it is ensured that the transition speeds of the machines are different from each other. Further, due to such characteristics, for example, the second transition speed of the second rotating machine can be made to coincide with the ideal operating point of the first rotating machine at which the first mechanical torque generated by the first machine is stabilized, and the torque reduction can be further reduced.
[0013] Advantageously, the first command is a pulse width modulation signal and the second command is a full-wave signal. "Pulse width modulation (PWM)" is an expression commonly used by those skilled in the art. "Full-wave" is an expression commonly used by those skilled in the art.
[0014] Advantageously, the control module is configured to transmit the first command to the first rotating machine when the first rotating machine is rotating at a speed lower than the first transition speed, and to transmit the second command to the first rotating machine when the first rotating machine is rotating 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 when the second rotating machine is rotating at a speed lower than the second transition speed, and to transmit the second command to the second rotating machine when the second rotating machine is rotating at a speed higher than the second transition speed.
[0016] Advantageously, the first rotating machine and the second rotating machine are electric motors.
[0017] Advantageously, the control device is an inverter connected to the phases of the first rotating machine and the second rotating machine.
[0018] According to another aspect of the present invention, the present invention relates to a moving machine including the above-described drive device.
[0019] The present invention will be better understood by reading the following description. The following description is merely an example and refers to the accompanying drawings as non-limiting examples with the same reference numerals being assigned to similar objects.
Brief Description of the Drawings
[0020]
Figure 1
Figure 2
Embodiments for Carrying Out the Invention
[0021] It should be noted that the drawings describe the present invention in detail so that the present invention can be implemented, but are not limiting. The said drawings are particularly used to better define the present invention as necessary.
[0022] The present invention relates to a drive device 2. The drive device 2 is particularly configured to rotationally drive a transfer element 4, for example, a differential that drives the wheels of a vehicle 1, as shown in Figure 1. The drive device 2 includes a first rotating machine 6 connected to the transfer element 4. The first rotating machine 6 is configured to generate a first mechanical torque C1 and transmit this first mechanical torque C1 to the transfer element 4 according to a first transmission ratio.
[0023] The drive device 2 includes a second rotating machine 8 connected to the transfer 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 transfer element 4 according to a second transmission ratio. Advantageously, the first transmission ratio is different from the second transmission ratio. In such a configuration, the two rotating machines can transmit the same mechanical torques C1, C2, for example, even if each rotating machine 6, 8 rotates at a different speed.
[0024] Therefore, the drive device 2 transmits the third mechanical torque C3 generated due to the first mechanical torque and the second mechanical torque to the transmission element 4.
[0025] In the embodiment described in FIG. 1, the vehicle 1 can be, in particular, an electric vehicle or a hybrid vehicle. In such a configuration, the first rotating machine 6 and the second rotating machine 8 are preferably electric motors.
[0026] The drive device 2 includes a control module 10 so as to be controlled by a user. The control module is configured to transmit a speed command to the first rotating machine 6 and 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 that connects to the phase of the first rotating machine 6 and the phase of the second rotating machine 8.
[0027] The speed command is selected from among the first command and the second command. The speed command transmitted to each rotating machine is a function of the transition speed of the machine. Therefore, the first rotating machine 6 has a first transition speed Ω1. Similarly, the second rotating machine 8 has a second transition speed Ω2. And the transition from one command transmitted to the first rotating machine 6 to the other command is a function of the first transition speed Ω1. The transition from one command transmitted to the second rotating machine 8 to the other command is a function of the second transition speed Ω2. The two transition speeds Ω1, Ω2 are different.
[0028] Advantageously, the first transition speed Ω1 is the result of the product of the second transition speed Ω2 and a speed coefficient less than 0.6. In such a configuration, it is ensured that the transition speeds Ω1, Ω2 of the rotating machines 6, 8 are different from each other. Furthermore, due to such characteristics, for example, the second transition speed Ω2 of the second rotating machine 8 can be made to coincide with the ideal operating point of the first rotating machine 6 at which the first mechanical torque C1 generated by the first machine 6 stabilizes, and torque reduction can be further reduced.
[0029] The transition from one command to the other can advantageously be achieved precisely when the rotary machines 6, 8 reach exactly the transition speeds Ω1, Ω2. Alternatively, the transition from one command to the other can be achieved when the rotational speeds of the rotary machines 6, 8 are in a range including the transition speeds Ω1, Ω2, for example, when they are 0.95 times the transition speed to 1.05 times the transition speeds Ω1, Ω2.
[0030] FIG. 2 shows a characteristic speed-torque curve showing the changes in the first mechanical torque C1, the second mechanical torque C2, and the resulting torque C3 as a function of the rotational speeds of the first rotary machine 6 and the second rotary machine 8.
[0031] When the first rotary machine 6 transitions from one command to the other, a decrease in the first mechanical torque C1 of the first rotary machine 6 is observed with respect to the rotational speed equal to the first transition speed Ω1. Similarly, when the second rotary machine 8 transitions from one command to the other, a decrease in the second mechanical torque C2 of the second rotary machine 8 is observed with respect to the rotational speed equal to the second transition speed Ω2.
[0032] Therefore, the drive device 2 can advantageously smooth the torque decreases observed in the characteristic curves of the first mechanical torque C1 and the second mechanical torque C2, respectively. Specifically, by combining the first rotary machine 6 and the second rotary machine 8 in the same transmission element, the characteristic curve of the resulting torque C3 is smoothed, that is, the observed torque decrease is reduced by approximately 40%.
[0033] Therefore, the discomfort caused by the torque decrease felt by the user of the vehicle 1 equipped with such a drive device 2 can be substantially reduced.
[0034] The curves in FIG. 2 show an embodiment in which the first command is a pulse-width modulation signal in particular and the second command is a full-wave signal. "Pulse-width modulation (PWM)" is an expression commonly used by those skilled in the art. "Full-wave" is an expression commonly used by those skilled in the art.
[0035] The control module 10 is configured to transmit a first command to the first rotating machine 6 when the first rotating machine 6 rotates at a speed lower than the first transition speed Ω1. Further, the control module 10 is configured to transmit a second command to the first rotating machine 6 when the first rotating machine 6 rotates at a speed higher than the first transition speed Ω1.
[0036] Furthermore, the control module 10 is configured to transmit the second command to the second rotating machine 8 when the second rotating machine 8 rotates at a speed lower than the second transition speed Ω2. Also, the control module 10 is configured to transmit the second command to the second rotating machine 8 when the second rotating machine rotates at a speed higher than the first transition speed Ω1.
[0037] It should be noted that the present invention is not limited to the above-described embodiments. Specifically, it will be apparent to those skilled in the art that various changes can be made to the above-described embodiments in light of the disclosed teachings.
[0038] The terms used in the detailed description of the present invention made above should not be construed as limiting the invention to the embodiments described herein, but should be construed to include all equivalents that can be provided within the scope of the ability of those skilled in the art by applying the general knowledge of those skilled in the art to the practice of the disclosed teachings.
Claims
1. A mechanical drive (2) configured to drive in rotation a transmission element (4), a first rotating machine (6) connected to said transmission element (4) according to a first transmission ratio, said first rotating machine (6) having a first predetermined transition speed (Ω1); a second rotating machine (8) connected to said transmission element (4) according to a second transmission ratio, said second rotating machine (8) having a second predetermined transition speed (Ω2) different from said first transition speed (Ω1); a control module (10) configured to transmit speed commands of 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 transmitted to the first rotating machine (6) being a function of the first transition speed (Ω1) and the transition from one command to the other transmitted to the second rotating machine (8) being a function of the second transition speed (Ω2); A drive unit (2) comprising:
2. the first transmission ratio is different from the second transmission ratio; A drive device (2) according to claim 1.
3. the second transmission ratio being the result of the product of the first transmission ratio and a transmission coefficient less than 0.6; A drive device (2) according to claim 2.
4. the first transition rate (Ω1) is the result of the product of the second transition rate (Ω2) and a rate factor less than 0.6; A drive device (2) according to any one of the preceding claims.
5. the first command is a pulse width modulated signal and the second command is a full wave signal; A drive device (2) according to any one of the preceding claims.
6. the control module (10) is configured to transmit the first command to the first rotating machine (6) when the first rotating machine (6) rotates at a speed lower than the first transition speed (Ω1) and to transmit the second command to the first rotating machine (6) when the first rotating machine (6) rotates at a speed higher than the first transition speed (Ω1); A drive device (2) according to claim 5.
7. the control module (10) is configured to transmit the second command to the second rotating machine (8) when the second rotating machine (8) rotates at a speed lower than the second transition speed (Ω2) and to transmit the second command to the second rotating machine (8) when the second rotating machine (8) rotates at a speed higher than the second transition speed (Ω2); A drive device (2) according to claim 5 or 6.
8. the first rotating machine (6) and the second rotating machine (8) are electric motors; A drive device (2) according to any one of the preceding claims.
9. the control module (10) being an inverter connected to a phase of the first rotating machine (6) and to a phase of the second rotating machine (8); A drive device (2) according to claim 8.
10. An electric or hybrid vehicle (1) comprising a drive device (2) according to any one of the preceding claims.