Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
  • B60L7/00—Electrodynamic brake systems for vehicles in general
  • B60L7/10—Dynamic electric regenerative braking
  • B60L7/18—Controlling the braking effect
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/60—Other road transportation technologies with climate change mitigation effect
  • Y02T10/72—Electric energy management in electromobility

Definitions

• the present invention relates to electric vehicles and, more particularly in such vehicles, a method of calculating and applying an electric braking torque of the vehicle.
• the object of the present invention is therefore to implement, in an electric vehicle, an electric braking method which does not have the drawbacks of the solutions currently known and succinctly set out above.
• This object is therefore to implement an electric braking method which in particular simulates a braking torque substantially equivalent to the engine brake, existing on a thermal vehicle and the absence of which on electric vehicles seems unnatural to the driver of such a vehicle. .
• This object is achieved by introducing a braking torque on the electric motor of the vehicle, the value of which is a function of the speed of movement of the vehicle, its acceleration, actuation of the brake and accelerator pedals and activation of an anti-lock device for the wheels.
• the present invention provides a braking method for an electric vehicle comprising:
• an accelerator pedal (2) associated with a device (1) for measuring the position of said pedal to supply signals representative of this position
• a brake pedal (3) associated with a device for detecting (4) the start of the travel of said pedal to provide a signal representative of this start of travel
• V_VE speed of movement
• A_VE deceleration
• V_VE first component CFj
• A_VE a second component CF2 (A_VE), proportional to the deceleration of the vehicle, of the value of the braking torque CF, - calculate according to whether or not a signal representative of the actuation of the brake pedal is detected, a value of the braking torque CF equal to the sum CF (V_VE) + CFj (A_AE) or CF (V_VE),
• CF 2 (A_VE) K.A_MINI2. ⁇ (A_MINI3 - A_VE) / (A_MINI3 - A_MINI2) ⁇ , as long as the value of the deceleration remains between the first threshold (A_MINI2) and a second predetermined threshold (A_MINI3).
• the component CF (V_VE) of the braking torque is of the form:
• V_VE ai + b ⁇ .V_VE as long as the speed value (V_VE) of the vehicle remains greater than a predetermined value (V_MINI).
• the coefficient K is strictly positive.
• the coefficients al and bl are strictly positive and negative respectively.
• the braking torque is zero, when at least one of the following conditions is achieved:
• V_VE vehicle speed
• V_MINI predetermined threshold
• FIG. 1 is a functional diagram of an electric vehicle implementing the braking method according to the invention
• FIG. 2 is a diagram which makes it possible to describe the braking method according to the invention
• FIG. 3 is a diagram showing, as a function of the vehicle speed, the values of the electric braking torque, in a first braking zone, of an electric vehicle according to the invention, and of the braking torque corresponding to " engine brake "of an equivalent engine vehicle.
• An electric vehicle conventionally comprises:
• an electric motor 10 the output shaft 19 of which is mechanically connected to the drive wheels 13 by a differential reduction device 12, a storage battery 14 for storing electric energy,
• an accelerator pedal 2 associated with a device 1 for measuring the position of said pedal to supply signals representative of this position
• a brake pedal 3 associated with a device for detecting the start of travel 4 of said pedal to provide a signal representative of this start of travel
• - means 21 for measuring the speed of rotation of the driving wheels 13 or of the electric motor 10 to supply the traveling speed V_VE of the electric vehicle
• a computer 15 for calculating the value Ie of the power supply current to the motor 10, the so-called reference value, which is applied to the control device 9 to enable it to carry out the switching of the battery current to the electric motor of the same type as the latter provides a torque corresponding to the set value le.
• the calculator includes for information:
• the computer 8 supplies the value of the setpoint current le on the connection cable 21.
• a brake light 5 which is supplied by the battery 15 via the conductors 14 is associated with the brake pedal 3 and with the device for detecting the start of the stroke 4 of the said pedal.
• the braking method according to the invention is implemented by the computer 8 from signals representative of the positions of the accelerator pedal 2, from a start of travel contact of the pedal. brake 3 activating the STOP light 5, activation of the anti-lock device 20 of the wheels, and the respective values of the speed V_VE and the instantaneous acceleration A_VE of the vehicle.
• the flow diagram of this method is represented in FIG. 2 and begins with the measurement of the speed of the vehicle V_VE by an appropriate sensor 11 or by an estimation of the latter using a signal representative of the rotation of the engine. traction of the vehicle.
• the acceleration A_VE of the vehicle is calculated in a manner known per se, from the information on the speed of movement V_VE of the vehicle; these values A_VE and V_VE correspond respectively to the instantaneous acceleration and speed of the vehicle.
• the braking method according to the invention distinguishes four electrical braking zones of the vehicle:
• the first zone corresponds to an applied electric braking torque dependent on the vehicle speed alone; in this zone, the applied electric braking torque is preferably based on the average value of the braking torque due to the engine brake of a thermal vehicle of substantially equivalent power.
• the values of the parameters aj and bj are chosen accordingly.
• FIG. 3 shows a diagram representative of the electric braking torque (dotted curve) in this area, as well as the braking torque (solid line curve) corresponding to the "engine brake" of the vehicle equipped with a heat engine of substantially equivalent power associated with a four-speed gearbox; remember that on a vehicle with an internal combustion engine, the braking torque due to the engine brake depends on both the gear engaged and the speed of the vehicle.
• the second zone corresponds to mechanical braking for low deceleration and without skidding of the drive wheels
• the third zone corresponds to a transition between braking of low deceleration to that of strong deceleration where the electric braking is eliminated for safety reasons; the choice of the value A_MINI2 delimits the passage between the second and third zones.
• the fourth zone corresponds to a zero electric braking torque beyond a maximum deceleration threshold A_MINI3, the value of which delimits the border between the third and fourth zones.
• the braking torque chosen is a torque CF (V_VE) proportional to the speed V_VE of the vehicle.
• V_VE torque CF
• V_VE a ⁇ + b ⁇ .V_VE, the values of a ⁇ and b ⁇ being chosen respectively strictly negative and positive.
• the method according to the invention provides for three possible cases according to the value of the acceleration A_VE of the vehicle with respect to two values A_MINI2 and A_MINI3 which correspond respectively to predetermined maximum and minimum deceleration thresholds.
• this first braking torque is the form:
• CF i (A_VE) K.
• a VE with K strictly positive.
• the computer calculates a second braking torque CF equal to the sum of an electric braking torque depending on the speed CF (V_VE) and d ' a second braking torque depending on the deceleration CF2 (A_VE).
• this second braking torque is the form:
• CF2 (A_VE) K.A_MINI2. ⁇ (A_MINI3-A_VE) / (A_MINI3 - A_MINI2) ⁇
• This formulation makes it possible to obtain continuity in the value of the braking torque between the second and third deceleration zones.
• the rectangle 41 indicates the value of the setpoint torque which is applied and which is the sum of the setpoint of the torque Ce in the absence of implementation of the method according to the invention and of the value CF calculated according to said method.
• the braking method according to the invention therefore has the advantage of introducing an electric braking torque varying continuously as a function of the deceleration; moreover, it allows the driver to rediscover the familiar feeling of the engine brake; it only requires the use of a limit switch, less expensive than a potentiometer, for the brake and accelerator pedals; the cost of the vehicle is reduced accordingly and its reliability increased.
• the braking process also has full compatibility with the anti-lock devices existing on electric vehicles.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Regulating Braking Force (AREA)
• Electric Propulsion And Braking For Vehicles (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=9498165

Family Applications (1)

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Family Cites Families (4)

• 1996
  • 1996-11-29 FR FR9614647A patent/FR2756520B1/fr not_active Expired - Fee Related
• 1997
  • 1997-11-28 TW TW086117948A patent/TW349063B/zh active
  • 1997-11-28 EP EP97948948A patent/EP0941165A1/de not_active Withdrawn
  • 1997-11-28 WO PCT/FR1997/002146 patent/WO1998023461A1/fr not_active Application Discontinuation

Non-Patent Citations (1)

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