METHOD FOR DAMPING THE TRANSMISSION OF AN ELECTRIC MOTOR VEHICLE

Abstract

The invention relates to an electric or hybrid motor vehicle (100) comprising a computer (50) and an actuator (95) operable by a driver, an electric traction motor (60), a transmission (70) for driving a rolling member (80), said computer (50) comprising a feedback loop at the output of the motor (60), an anti-oscillation controller (10) arranged to calculate a counter-reaction, with calculation means modeling the torsional speed of the transmission (70), arranged to calculate an estimate of the transfer function between the torsional speed and the speed of the engine (60), on the basis of an estimator (40) of the torsional speed of said transmission (70) implementing a second-order transfer function of two physical parameters which are the natural pulsation and the damping of the transmission. The invention relates to a method for damping the transmission of such a vehicle on the basis of this estimate. Figure 8

Description

Title of the invention: METHOD FOR DAMPING THE TRANSMISSION OF AN ELECTRIC MOTOR VEHICLE

[0001] The invention relates to an electric or hybrid motor vehicle, comprising control means comprising a computer and an actuator arranged to be operated by a driver, at least one electric traction motor, a transmission arranged to drive a rolling member, said computer comprising an input line for controlling said at least one electric traction motor on the basis of an input signal from an input instruction emanating from said actuator, and, on a feedback loop at the output of said at least one electric traction motor, an anti-oscillation controller which is arranged to calculate a feedback, said computer comprising an operator which is arranged to subtract said feedback from said input signal, to define the control of said at least one electric traction motor.

[0002] The invention also relates to a method for damping the transmission of such an electric or hybrid motor vehicle.

[0003] The invention relates to the field of the performance of the transmission of an electric or hybrid motor vehicle, and in particular of anti-oscillation behavior, of the search for driving pleasure, and of the definition of control laws appropriate to the safety of the vehicle and to the handling by the driver.

[0004] In order to eliminate the oscillations of the transmission of an electric or hybrid motor vehicle, the implementation of an anti-oscillation controller 10, as visible in [Fig.l], on an electric or hybrid motor vehicle 100, comprising a computer 50, an electric traction motor 60, a transmission 70, and a rolling member 80, is known. According to the state of the art, its action can be constructed in two ways: - a proportional-derivative action on the torsion speed (primary shaft speed - wheel speed, described by the document FR3054989B): the electric or hybrid motor vehicle 100 comprises a computer 50 provided with an anti-oscillation controller module 10, based on two measurements of the speed, on the one hand the coM speed of a primary shaft at the level of an electric traction motor 60, and on the other hand the coR speed measured at the wheel 80 in order to develop the feedback control. The computer 50 couples the order given by the driver to the level of an actuator 95, constituted by the accelerator pedal or a similar actuator such as a lever, slider, ring of steering wheel, voice actuator or other, and constituting an input of this calculator 50, with the output of the anti-oscillation controller module 10, to control the electric traction motor 60; - a proportional action on the machine speed (primary) filtered by a low-pass filter and a high-pass filter: this solution uses only the coM machine speed (primary shaft) in order to develop the feedback control.

[0005] The first solution, based on the two measurements of the speed, on the one hand the coM speed of a primary shaft at the level of an electric traction motor, and on the other hand the coR speed measured at the wheel has a limited efficiency, although it directly exploits the information faithfully representing the oscillation of the transmission (torsion speed). Indeed, the delay time of the coR wheel speed information (from the CAN messaging "Controller area network", serial system bus standardized with the ISO 118987 standard) is close to the natural response time of the transmission. As a result, the oscillation cannot be sufficiently damped at the risk of causing the feedback loop to become unstable.

[0006] The second solution avoids the measurement of the coR wheel speed by using a cascade of first-order low-pass and high-pass filters to reconstruct the torsional regime. However, it also does not faithfully reproduce the torsional regime as shown in [Fig.2]: in fact, the first peak is not entirely reconstructed, and the reconstructed torsional regime has a bias in static regime. This solution does not allow the first oscillation peak to be attenuated and can generate a bias on the driver torque. This estimation error significantly degrades the performance of the anti-oscillation controller.

[0007] The objective of the present invention is to overcome these drawbacks by proposing a rigorous estimation of the torsion regime via a physical model, to achieve the expected performance. Indeed, the transfer function between the torsion regime and the machine regime (primary shaft) cannot be reduced to a cascade of low-pass and high-pass filters.

[0008] To achieve this objective, the invention proposes an electric or hybrid motor vehicle, comprising control means comprising a computer and an actuator arranged to be operated by a driver, at least one electric traction motor, a transmission arranged to drive a rolling member, said computer comprising an input line for controlling said at least one electric traction motor on the basis of an input signal from an input instruction emanating from said actuator, and, on a feedback loop at the output of said at least one electric traction motor, an anti-oscillation controller which is arranged to calculate a feedback, said computer comprising an operator which is arranged to subtract said feedback from said input signal, to define the control of said at least one electric traction motor.

[0009] According to the invention, said anti-oscillation controller comprises calculation means arranged to model the torsion regime of said transmission, and which are arranged to calculate, at each instant, an estimate of the transfer function between the torsion regime and the regime of said at least one electric traction motor, on the basis of an estimator of said torsion regime of said transmission implementing a second-order transfer function of two physical parameters which are the natural pulsation and the damping of the transmission.

[0010] Thanks to the invention, a rigorous estimation of the torsion regime makes it possible to achieve the expected performance in terms of damping of the vehicle transmission.

[0011] Advantageously, said calculation means are arranged to model the torsion regime of said transmission by assimilating it to a modeled system comprising two masses connected to each other by a spring and a damper, comprising a first mass of first inertia equivalent to the sum of the inertias upstream of a differential that said transmission comprises with an input speed and a primary input torque and a primary input angular position, and a second mass of second inertia equivalent to the sum of the inertias downstream of said differential with an output speed and a secondary output torque and a secondary output angular position, said calculation means being arranged to calculate a torsion speed coT such that: coT = cop - cor, where cop is said input speed and where cor is said output speed, a torsion angle 0T such that: 0T = 0P - 0r,where 0P is the value of said primary input angular position, and where 0r is the value of said secondary output angular position, and to calculate a torsional torque CT such that: CT = (Kr.0T) + (Kv .œT), where Kr is the torsional stiffness constant of said spring, and where Kv is the viscous friction constant of said damper, said calculation means being further arranged to compare the input and output torques of the modeled system and to apply Newton's Law to it to obtain two equations Jp. dcüp / dt = Cp - CT and Jr. dcor / dt = Cr+ CT, where Jp is said first inertia of said first mass and where Jr is said second inertia of said second mass, where Cp is the value of said primary input torque and where Cr is the value of said secondary output torque,said calculating means being further arranged to cancel the value of said secondary output torque (Cr) and subtract said two equations to obtain a torsional acceleration dcoT / dt = (Cp / Jp) - (Ct / Jt), with JT such that 1 / JT = (Jp + Jr) / (JP. Jr), said calculating means being further arranged to obtain another expression of said torsional acceleration such that: dcoT / dt = (dcop / dt) - (l / Jr).CT, to replace said torsion torque CT by its value such that: CT = (Kr.0T) + (Kv.œT), and to derive it with respect to time to obtain a transfer function such that: coT(s) = (s2). œp(s). l / (s2 + s. , Kv / Jr + Kr / Jr), which represents said estimator (40) which is represented by a second-order transfer function of the general form: coT(s) = (s2). a>p(s). l / (s2 + 2 s. Ç. + °o2 y with as natural pulsation and with as damping Ç = kv . 1 / (2^777).

[0012] Thus the simulation of the vibratory system constituted by the transmission is done exactly, without the approximations of the prior art.

[0013] Advantageously, said anti-oscillation controller is arranged to evaluate the feedback on the basis of said transfer function estimator, and a gain stage is arranged between said anti-oscillation controller and said operator.

[0014] This configuration makes it possible to maintain a very simple architecture calculator.

[0015] Advantageously, said computer comprises, on said control input line of said at least one electric traction motor, a setpoint filtering module which is arranged to filter said input setpoint emanating from said actuator, to deliver said input signal to said operator.

[0016] This frees us from the games and non-linearities that the system may contain.

[0017] Advantageously, said rolling member is connected to said computer only by said at least one traction motor and by said transmission.

[0018] Thus the control of each traction motor is done exactly by calculation, and is not altered by the feedback of the rotation speed of the running gear.

[0019] The invention also relates to a method for damping the transmission of such an electric or hybrid motor vehicle.

[0020] According to the invention, said transmission is modeled and said estimator of the torsional speed of said transmission is produced on the basis of technical data of said transmission and / or development tests of a typical vehicle, and the drive of said rolling member of said electric or hybrid motor vehicle is controlled solely on the basis of the input instruction given by a driver on said actuator and on the primary speed of said at least one electric traction motor.

[0021] This eliminates the need for a connection between the computer and a sensor on the rolling element. A rigorous estimation of the torsion regime is carried out, which makes it possible to achieve the expected performance in terms of damping of the vehicle's transmission.

[0022] Advantageously, said calculation means are arranged to model the torsion regime of said transmission by assimilating it to a modeled system comprising two masses connected to each other by a spring and a damper, comprising a first mass of first inertia equivalent to the sum of the inertias upstream of a differential that said transmission comprises with an input speed and a torque primary input and a primary input angular position, and a second mass of second inertia equivalent to the sum of the inertias downstream of said differential with an output speed and a secondary output torque and a secondary output angular position.

[0023] Thus we make an exact simulation of the vibratory system constituted by the transmission.

[0024] Advantageously, said anti-oscillation controller is arranged to evaluate the feedback on the basis of said estimator of the transfer function, and a gain stage is arranged between said anti-oscillation controller and said operator.

[0025] This maintains a calculator with a very simple architecture.

[0026] Advantageously, said computer is equipped, on said control input line of said at least one electric traction motor, with a setpoint filtering module which is arranged to filter said input setpoint emanating from said actuator, to deliver said input signal to said operator.

[0027] This frees us from the games and non-linearities that the system may contain.

[0028] Advantageously, any connection between said calculator and any existing means of speed control of said rolling member of said electric or hybrid motor vehicle is removed.

[0029] Thus the control of each traction motor is done exactly by calculation, and is not altered by the feedback of the rotation speed of the running gear.

[0030] The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the appended figures illustrating variants of the invention, in which: - [Fig.l] schematically illustrates an electric or hybrid motor vehicle, comprising a computer equipped with an anti-oscillation controller module, based on the measurement of the speed of a primary shaft at the level of an electric traction motor, and the speed measured at the wheel; - [Fig.2] is a curve which schematically illustrates the estimation of the regime of state-of-the-art torsion, in broken line, to be compared with the wT torsion regime, in solid line; - [Fig.3] represents the open loop response of the transmission to a primary driver torque step without anti-oscillation strategy or filtering, with the primary regime wp in solid line, and the torsion regime wT in broken line; - [Fig.4] schematically illustrates a modeling of a transmission of vehicle, with two masses, spring and shock absorber; - [Fig.5] compares the response of the transfer equation calculated according to the invention, in solid line, compared to that of the state of the art consisting of a cascade of two low-pass and high-pass filters in a broken line; - [Fig.6] illustrates the anti-oscillation feedback loop according to the invention, where the anti-oscillation controller evaluates the feedback on the basis of an estimator of the transfer function calculated according to the invention, before a gain stage prior to the arithmetic operator performing the subtraction of the result at the gain output from the driver setpoint; - [Fig.7] illustrates the comparison of the performances of the solution of the present invention in solid line, and that of the state of the art in broken line; - [Fig.8] schematically illustrates an electric motor vehicle or hybrid, according to the invention comprising a computer equipped with an anti-oscillation controller module, based on the measurement of the speed of a primary shaft at the level of an electric traction motor, the anti-oscillation controller module comprising an estimator of the torsion speed of the vehicle transmission.

[0031] [Fig.l] schematically illustrates an electric or hybrid motor vehicle 100, comprising control means 200 comprising a computer 50 and an actuator 95 arranged to be operated by a driver, an electric traction motor 60, a transmission 70 arranged to drive a rolling member 80.

[0032] The computer 50 comprises an input line for controlling the at least one electric traction motor 60 on the basis of an input signal from an input instruction emanating from the actuator 95, and, on a feedback loop at the output of the at least one electric traction motor 60, an anti-oscillation controller 10. This anti-oscillation controller is arranged to calculate a feedback. The computer 50 comprises an operator 20 which is arranged to subtract this feedback from the input signal, to define the control of the at least one electric traction motor 60.

[0033] More particularly, the computer 50 comprises, on this control input line of the at least one electric traction motor 60, a setpoint filtering module 90 which is arranged to filter the input setpoint emanating from the actuator 95, to deliver the input signal to the operator 20.

[0034] In particular and non-limitingly, the computer 50 thus comprises an anti-oscillation controller 10, and a setpoint filtering module 90, the input 95 of which is constituted by the accelerator pedal. This computer 50 couples the order given by the driver at the input 95, via the setpoint filtering module 90, with the output of the anti-oscillation controller module 10, to control the at least one electric traction motor 60. For this purpose, the computer 50 comprises an operator 20 arranged to subtract the output of the anti-oscillation controller module 10 from the input signal emanating from the setpoint filtering module 90.

[0035] More particularly, the invention relates to an active method of damping the transmission of an electric vehicle, making it possible to do without a speed sensor at the wheel level.

[0036] The solution proposed in the present invention corrects the robustness problem of the second solution based on the cascade of low-pass and high-pass filters, by exploiting a physical model of the system. Thanks to this physical modeling, a simple solution for designing an estimator of the torsion regime is proposed. This estimator is easy to implement by a second-order transfer function having two physical parameters (natural pulsation and transmission damping). These latter physical parameters are easily identifiable from a vehicle tuning test.

[0037] [Fig-1] is an overall view of the system to be controlled and its control law. The electrical machine 60 produces the torque (or part of the torque) requested by the driver, taking into account the feedback from the anti-oscillation controller module 10. More precisely, the driver's request is filtered by the setpoint filtering module 90, in order to compensate for the non-linearities of the system such as backlash, and the feedback is removed from it in order to dampen the oscillations of the transmission.

[0038] [Fig.3] represents the open loop response of the transmission at a step of primary driver torque without anti-oscillation strategy or filtering. It can be seen that both the primary (wp) and torsion (wT) regimes have very weakly damped oscillations affecting driving pleasure.

[0039] The role of the anti-oscillation controller module 10 is then to develop a counter-reaction in order to sufficiently dampen (or even eliminate) these oscillations.

[0040] The calculations of the torsion regime estimator will be detailed below.

[0041] The transmission chain system can be represented by a system as illustrated in [Fig.4], with two masses, connected by a spring and damper. The inertia Jp represents the sum of the upstream inertias of the differential; gearbox, reducer, electric machine 60 and thermal engine if applicable. The inertia Jr represents the sum of the downstream inertias: rolling member 80 and the body. The viscous friction as well as the torsional stiffnesses of the transmission are represented by Kv and Kr respectively.

[0042] In the following, we will calculate the transfer function linking the machine speed (primary shaft) to the torsion speed. We will then show how to dampen the oscillations of the transmission thanks to a proportional feedback using this estimator 40. Finally, we will compare the results obtained with the state-of-the-art solution, and those obtained by the solution proposed according to the present invention.

[0043] We consider the torsion speed coT such that, according to equation (1): coT = cop - cor, and the torsion angle 0T such that, according to equation (2): 0T = 0P - 0r; thus, the torsion torque CT is written according to equation (3): CT = (Kr.0T) + (Kv.œT).

[0044] By taking stock of the torques on the primary shaft and the wheel and applying Newton's second law to the system of [Fig.4], we obtain equation (4): Jp. dcop / dt = Cp - CT, and equation (5): Jr. dcor / dt = Cr+ CT.

[0045] We then cancel the wheel torque Cr = 0 (disturbance) in equation (5), then we subtract the two equations (4) and (5), it follows equation (6): dcoT / dt = (Cp / Jp) - (CT / JT), with JT such that 1 / JT = (Jp + Jr) / (JP. Jr).

[0046] Replacing the primary torque from equation (4) in equation (6), it follows equation (7): dcoT / dt = (dcüp / dt) - (l / Jr).CT.

[0047] We then replace CT given by equation (3) in equation (7) and we derive the latter with respect to time to get rid of the torsion angle in the result. We then obtain the transfer function according to equation (8): coT(s) = (s2). cop (s). l / (s2 + s. Kv / Jr + KA).

[0048] The estimator 40 is therefore represented by a second-order transfer function of the general form according to equation (9): coT(s) = (s2). œp(s). l / (s2 + 2 s. Ç. + ^o2), with natural pulsation j jr, and damping Ç = Kv. UVjKlJr)-

[0049] We then note that the transfer function (9) cannot be put in the form of a cascade of two first-order low-pass and high-pass filters. Indeed, as Ç is less than 1: the denominator of equation (9) cannot be decomposed into a product of two monomials in s. Furthermore, the order of the numerator of equation (9) is greater than 1.

[0050] [Fig.5] compares the response of equation (9) with that of the state of the art consisting of a cascade of two low-pass and high-pass filters. The estimator of the present invention faithfully reproduces the torsion regime, while that of the state of the art presents an error on the first peak as well as a bias in steady state.

[0051] In order to show the contribution of the new estimator 40, the latter is inserted into the feedback loop according to the diagram of [Fig.6] in place of the state-of-the-art estimator. [Fig.6] illustrates the anti-oscillation feedback loop according to the invention, where the anti-oscillation controller evaluates the counter-reaction on the basis of the estimator of the transfer function calculated according to the invention, according to equation (9), before a gain stage prior to the arithmetic operator performing the subtraction of the result at the gain output from the driver setpoint.

[0052] We then compare the actual torsion obtained in closed loop with the two devices. We then note that the proposed solution reduces the first peak better compared to the state of the art. It achieves damping respecting the specifications unlike the state of the art solution while the state of the art solution still generates several overruns.

[0053] [Fig.7] illustrates the comparison of the performances of the solution of the present invention in solid line, and that of the state of the art in broken line.

[0054] The proposed solution improves driving pleasure by ensuring good damping of the transmission. It also facilitates the development of the anti-oscillation corrector, thanks to a reduced number of adjustment parameters and their physical meaning. Furthermore, the parameters of the estimator can be easily identified on the development means.

[0055] In short, the present invention uses a rigorous model of the transmission allowing its torsion regime to be faithfully reconstructed. The latter is based on the physical modeling of the transmission, and is therefore quite easy to implement and calibrate from simple tests carried out on a vehicle, or by knowing the physical parameters of the transmission. This device does not use a wheel speed sensor, and therefore overcomes the problem of delay linked to CAN messaging. Inserted into the anti-oscillation feedback loop, it simplifies the development of the anti-oscillation function, and it significantly improves driving pleasure and safety.

Claims

Claims

1. Electric or hybrid motor vehicle (100), comprising control means (200) comprising a computer (50) and an actuator (95) arranged to be operated by a driver, at least one electric traction motor (60), a transmission (70) arranged to drive a rolling member (80), said computer (50) comprising an input line for controlling said at least one electric traction motor (60) on the basis of an input signal from an input instruction from said actuator (95), and, on a feedback loop at the output of said at least one electric traction motor (60), an anti-oscillation controller (10) which is arranged to calculate a feedback, said computer (50) comprising an operator (20) which is arranged to subtract said feedback from said input signal, to define the control of said at least one electric traction motor (60),characterized in that said anti-oscillation controller (10) comprises calculation means arranged to model the torsion regime of said transmission (70), and which are arranged to calculate, at each instant, an estimate of the transfer function between the torsion regime and the regime of said at least one electric traction motor (60), on the basis of an estimator (40) of said torsion regime of said transmission (70) implementing a second-order transfer function of two physical parameters which are the natural pulsation and the damping of the transmission.,

2. Electric or hybrid motor vehicle (100) according to claim 1 characterized in that said calculation means are arranged to model the torsion regime of said transmission (70) by assimilating it to a modeled system comprising two masses connected to each other by a spring and a damper, comprising a first mass of first inertia equivalent to the sum of the inertias upstream of a differential that said transmission (70) comprises with an input speed and a primary input torque and a primary input angular position, and a second mass of second inertia equivalent to the sum of the inertias downstream of said differential with an output speed and a secondary output torque and a secondary output angular position, said calculation means being arranged to calculate a torsion speed coT such that: coT = cop - cor, where cop is said input speed and where cor is said output speed, an angle oftorsion 0T such that: 0T = 0P - 0r, where 0P is the value of said primary input angular position, and where 0r is the value of said secondary output angular position, and to calculate a torsion torque CT such that: CT = (Kr.0T) + (Kv.œT), where Kr is the torsional stiffness constant of said spring, and where Kv is the viscous friction constant of said damper, said calculation means being further arranged to compare the input and output torques of the modeled system and to apply Newton's Law to it to obtain two equations Jp. dcop / dt = Cp - CT and Jr.dco / dt = Cr+ CT, where Jp is said first inertia of said first mass and where Jr is said second inertia of said second mass, where Cp is the value of said primary input torque and where Cr is the value of said secondary output torque, said calculating means being further arranged to cancel the value of said secondary output torque (Cr) and subtract said two equations to obtain a torsional acceleration dcoT / dt = (Cp / Jp) - (Ct / Jt), with JT such that 1 / JT = (Jp + Jr) / (JP. Jr ), said calculating means being further arranged to obtain another expression of said torsional acceleration such that: dcoT / dt = (dcop / dt) - (l / Jr).CT, to replace said torsional torque CT by its value such that: CT = (Kr.0T) + (Kv.œT), and to derive it with respect to time to obtain a transfer function such that: coT(s) = (s2). œp(s). l / (s2 + s.KV / Jr + Kr / Jr), which represents said estimator (40) which is represented by a second-order transfer function of the general form: coT(s) = (s2). œp(s). l / (s2 + 2 s. Ç. ®o + °o2), with as natural pulsation °o = ^Kr ] Jr ' ct with as damping Ç = Kv. U(2^Kr Jr )•.

3. Electric or hybrid motor vehicle (100) according to any one of claims 1 or 2 characterized in that said anti-oscillation controller (10) is arranged to evaluate the feedback on the basis of said estimator (40) of the transfer function, and characterized in that a gain stage (30) is arranged between said anti-oscillation controller (10) and said operator (20).

4. Electric or hybrid motor vehicle (100) according to any one of claims 1 to 3 characterized in that said computer (50) comprises, on said control input line of said at least one electric traction motor (60), a setpoint filtering module (90) which is arranged to filter said input setpoint emanating from said actuator (95), to deliver said input signal to said operator (20).

5. Electric or hybrid motor vehicle (100) according to any one of claims 1 to 4 characterized in that said rolling member (80) is connected to said computer (50) only by said at least one traction motor (60) and by said transmission (70).

6. Method for damping the transmission of an electric or hybrid motor vehicle (100) according to any one of claims 1 to 5, characterized in that said transmission (70) is modeled and said estimator (40) of the torsional speed of said transmission (70) is produced on the basis of technical data of said transmission (70) and / or development tests of a typical vehicle, and in that the drive of said rolling member (80) of said electric or hybrid motor vehicle (100) is controlled solely on the basis of the input instruction given by a driver on said actuator (95) and on the primary speed of said at least one electric traction motor (60).

7. Method according to claim 6, characterized in that said calculation means are arranged to model the torsion regime of said transmission (70) by assimilating it to a modeled system comprising two masses connected to each other by a spring and a damper, comprising a first mass of first inertia equivalent to the sum of the inertias upstream of a differential that said transmission comprises with an input speed and a primary input torque and a primary input angular position, and a second mass of second inertia equivalent to the sum of the inertias downstream of said differential with an output speed and a secondary output torque and a secondary output angular position, and characterized in that said calculation means are arranged according to claim 2.

8. Method according to claims 6 and 7 characterized in that said anti-oscillation controller (10) is arranged to evaluate the feedback on the basis of said estimator (40) of said transfer function, and in that a gain stage (30) is arranged between said anti-oscillation controller (10) and said operator (20).

9. Method according to any one of claims 6 to 8, characterized in that said computer (50) is equipped, on said control input line of said at least one electric traction motor (60), with a setpoint filtering module (90) which is arranged to filter said input setpoint emanating from said actuator (95), to deliver said input signal to said operator (20).

10. Method according to any one of claims 6 to 9 characterized in that any connection between said calculator (50) and any existing means of speed control of said rolling member (80) of said electric or hybrid motor vehicle (100) is removed.

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