EP4662083A1 - Method for recovering electrical energy and motor vehicle equipped for this - Google Patents

Method for recovering electrical energy and motor vehicle equipped for this

Info

Publication number
EP4662083A1
EP4662083A1 EP24700882.4A EP24700882A EP4662083A1 EP 4662083 A1 EP4662083 A1 EP 4662083A1 EP 24700882 A EP24700882 A EP 24700882A EP 4662083 A1 EP4662083 A1 EP 4662083A1
Authority
EP
European Patent Office
Prior art keywords
inverter
power consumption
consumption capacity
battery
brake
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP24700882.4A
Other languages
German (de)
French (fr)
Inventor
Marcel Freimuth
Sven KNOBLICH
Marion Lang
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Stellantis Auto SAS
Original Assignee
Stellantis Auto SAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Stellantis Auto SAS filed Critical Stellantis Auto SAS
Publication of EP4662083A1 publication Critical patent/EP4662083A1/en
Pending legal-status Critical Current

Links

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
    • 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
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
    • B60L15/2009—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed for braking
    • 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
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
    • B60L58/12—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries responding to state of charge [SoC]
    • 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
    • B60L7/14—Dynamic electric regenerative braking for vehicles propelled by AC motors
    • 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
    • B60L7/16—Dynamic electric regenerative braking for vehicles comprising converters between the power source and the motor
    • 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
    • B60L7/24—Electrodynamic brake systems for vehicles in general with additional mechanical or electromagnetic braking
    • 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
    • B60L7/24—Electrodynamic brake systems for vehicles in general with additional mechanical or electromagnetic braking
    • B60L7/26—Controlling the braking effect
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
    • B60W30/18—Propelling the vehicle
    • B60W30/18009—Propelling the vehicle related to particular drive situations
    • B60W30/18109—Braking
    • B60W30/18127—Regenerative braking
    • 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
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/10—Vehicle control parameters
    • B60L2240/36—Temperature of vehicle components or parts
    • 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
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/52—Drive Train control parameters related to converters
    • B60L2240/525—Temperature of converter or components thereof
    • 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
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/54—Drive Train control parameters related to batteries
    • B60L2240/545—Temperature
    • 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
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/54—Drive Train control parameters related to batteries
    • B60L2240/547—Voltage
    • 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
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/54—Drive Train control parameters related to batteries
    • B60L2240/549—Current

Definitions

  • the present invention relates to a method for recovering electrical energy in a motor vehicle, in particular on braking of the motor vehicle.
  • the invention relates, furthermore, to a motor vehicle which is equipped for recovering electrical energy, and a computer program product which enables a computer to carry out the method.
  • the still unpublished patent application DE 10 2021 211 722.8 describes a method for recovering electrical energy in a motor vehicle, in which, when recovered electrical energy can not be removed from the vehicle battery, the electrical power consumption of a connected consumer is increased.
  • the problem is solved according to an aspect of the invention by a method with the steps: determining a deceleration requested - e.g. by a driver through actuating a brake pedal determining a present power consumption capacity of the inverter; and controlling the efficiency of the inverter by means of the present power consumption capacity and the requested deceleration.
  • the method according to the invention By the method according to the invention, kinetic energy of the vehicle, which can not be received by the battery, is released as thermal energy in the inverter.
  • the inverter is required in any case for operating the electric motor, the method is able to be applied in every electrically driven motor vehicle, without additional consumers being required.
  • the deceleration which his able to be achieved through recovery can not render superfluous a brake dissipating the received kinetic energy. If, however, such a brake must be present in the vehicle, it can be expediently integrated into the method according to the invention, by the controlling of the efficiency taking place furthermore taking into consideration a power consumption capacity of the brake.
  • the present power consumption capacity of the inverter can be assumed to be equal to that of the battery; however, this has the result that the deceleration which is able to be achieved is systematically estimated too low, as losses in the inverter remain unconsidered. It is therefore preferred to take into consideration the efficiency of the inverter in the estimation. In most application situations, the aim is to recover as much kinetic energy of the vehicle as possible and, for this, to operate the inverter under conditions in which it has an optimal efficiency; accordingly, the power consumption capacity of the inverter can be estimated as a product of the present power consumption capacity of the battery and of the optimal efficiency of the inverter.
  • the controlling of the efficiency can comprise: setting an optimal efficiency, when the power consumption capacity of the inverter, if applicable plus a power consumption capacity of the brake, is sufficient in order to provide the requested deceleration, and/or setting a suboptimal efficiency, when the power consumption capacity of the inverter, if applicable plus a power consumption capacity of the brake, is not sufficient in order to provide the requested deceleration, and/or raising the efficiency of the inverter, when the power consumption capacity of the inverter, if applicable plus a power consumption capacity of the brake, is sufficient in order to provide the requested deceleration, and/or reducing the efficiency of the inverter, when the power consumption capacity of the inverter, if applicable plus a power consumption capacity of the brake, is not sufficient in order to provide the requested deceleration.
  • a charging current, a charging voltage, a charging output or generally a measurement variable which enables a conclusion concerning the internal resistance of the battery, and/or of a temperature of the battery, can be referred to.
  • a present power consumption capacity of the brake its temperature can be measured; by means of a known thermal capacity of the brake, it can then be estimated how much energy the brake can still receive before it reaches a temperature at which damage can occur, or a correct braking function is no longer guaranteed.
  • the temperature of the brake can also be estimated by means of past braking performances.
  • the output which must be received by the brake can also be dictated by a possibly necessary protection of the inverter from overheating.
  • the determining of the present power consumption capacity of the brake can comprise the measuring of a temperature of the inverter or the estimating of the temperature of the inverter by means of past efficiencies.
  • the problem is solved by a motor vehicle with a chassis, an electric motor for driving the chassis, a battery and an inverter, which is optionally operable in order to drive the electric motor with energy from the battery, or to charge the battery with energy extracted from the movement of the motor vehicle, a dissipative brake and a control unit, wherein the control unit is configured to carry out the method which is described above.
  • An object of the invention is a computer program product with program code means which enable a computer to carry out the method which is described above, or to operate as control unit in the motor vehicle which is mentioned above.
  • Fig. 1 a block diagram of a motor vehicle
  • FIG. 2 a flow diagram of an operating method of the control unit of the motor vehicle of Fig. 1.
  • Figure 1 shows schematically a motor vehicle with an electric motor 1, which drives wheels of a chassis 3 via transmission 2.
  • a combustion engine 4 can be provided.
  • An inverter 5 supplies the electric motor 1 in motor operation with electrical energy from a battery 6; the inverter 5 also assists a generator operation, in which the battery 6 is charged with current from the electric motor 1.
  • a further converter 7 can be provided, in order to supply various electrical consumers of the vehicle which are known perse and are not described here.
  • a charging interface 8 serves for the re-charging of the battery 6 from an external energy source.
  • a control unit 9 is connected to an accelerator pedal 10, in order to detect an acceleration of the vehicle requested by a driver, and in order to control the inverter
  • control unit 9 is connected to a brake pedal 11 , in order to detect a desired deceleration and to control the inverter 5 and brakes 12 of the vehicle in a suitable manner for producing this deceleration.
  • the control unit 9 In order to be able to recover here as much kinetic energy as possible which is extracted from the vehicle, the control unit 9 must take into consideration how much electrical output the battery 6 can receive in its present charging state.
  • the control unit 9 is connected to a charge state sensor 13, which estimates and emits a charge state of the battery 6 in any known manner, whether by measuring a battery internal resistance, of charging current and charging voltage, or by integration of current flows from and to the battery 6, and has e.g. a lookup table or a programmed calculation specification, which specifies a maximum charging current for the battery
  • Fig. 2 shows by means of a flow diagram an operating method of the control unit 9, repeated at regular time intervals, typically several times during an actuation of the brake pedal 11.
  • step S1 the charge state of the battery 5 is updated by means of data of the sensor 13, and a maximum permissible charging current l ma x is determined for this charge state (and if applicable the present temperature of the battery 5).
  • step S2 the brake pedal 11 is interrogated for a desired deceleration at arg et.
  • Step S3 calculates by means of the mass and the present speed of the vehicle a braking power Ptarget necessary for the desired deceleration atarget. This can be converted by means of wherein II designates the battery voltage and q designates the present efficiency of the inverter 5, into a charging current Itarget, which would result if the desired deceleration atarget were generated solely through recuperation operation of the inverter 5.
  • the control unit 9 checks whether the brakes 12 are to be referred to in a supporting manner, or whether the efficiency of the inverter 5 can and is to be reduced.
  • the brakes 12 are referred to (S6), in order to contribute the entire difference between the requested deceleration and that which the inverter can provide with a maintaining of the efficiency r
  • the control unit 9 then increases the clock rate f of the inverter 5 (S8), in order to set in this way a lower efficiency r
  • this has the result that the mechanical output which the electric motor 1 receives, in order to generate the maximum permissible charging current l ma x, increases.
  • the brakes can be relieved with unchanged deceleration.
  • control unit can directly set the lower efficiency (S8) and can only then refer to the brakes if otherwise the inverter is threatening to overheat, or in this case at the same time the brakes can be referred to, and the efficiency of the inverter can be reduced.
  • the inverter 9 When the inverter 9 operates with reduced efficiency, it is expedient to also monitor its temperature and to check (S9) whether an upper threshold of the permissible operating temperature is reached. If this is the case, the efficiency is raised again (S10), and the contribution of the brakes to the deceleration of the vehicle is increased.
  • the efficiency which is set at the end of the method described above can be used as initial value of the efficiency in a subsequent iteration of the method; thus, the efficiency can be reduced successively in the course of several repetitions of the step S8 (or in several repetitions of the step S10 can be brought closer again successively to the optimal value).
  • Such a successive changing can consist in that in each performance of step S8 the clock frequency f is multiplifed with a predetermined factor >1 , and in S10 is divided by the same or another factor.
  • the factor can be selected as a function of the difference Itarget-lmax, in order to arrive at a suitable value of the efficiency in the course of few iterations.
  • the optimal efficiency can be set immediately, in order to quickly reduce the release of heat in the inverter.

Landscapes

  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Automation & Control Theory (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)

Abstract

A motor vehicle comprises a chassis (3), an electric motor (1) for driving the chassis (1), a battery (6) and an inverter (5), which is optionally operable in order to drive the electric motor (1) with energy from the battery or to charge the battery (6) with energy extracted from the movement of the motor vehicle, and a control unit (9). The control unit is configured for -- determining (S2) a requested deceleration (atarget); - determining a present power consumption capacity of the inverter (5); and - controlling the efficiency of the inverter by means of the present power consumption capacity and the requested deceleration.

Description

METHOD FOR RECOVERING ELECTRICAL ENERGY AND MOTOR VEHICLE EQUIPPED FOR THIS
D E S C R I P T I O N
The present invention relates to a method for recovering electrical energy in a motor vehicle, in particular on braking of the motor vehicle. The invention relates, furthermore, to a motor vehicle which is equipped for recovering electrical energy, and a computer program product which enables a computer to carry out the method.
The still unpublished patent application DE 10 2021 211 722.8 describes a method for recovering electrical energy in a motor vehicle, in which, when recovered electrical energy can not be removed from the vehicle battery, the electrical power consumption of a connected consumer is increased.
The number of electrical consumers in a motor vehicle, the performance of which can be briefly arbitrarily raised in the required manner, is small; only components of a vehicle air-conditioning system are named as an application example. In a vehicle without an air-conditioning system, the conventional technology which is described above is therefore not able to be practically used.
Basically, it is indeed possible, on a decelerating of the vehicle, to dispense with the recuperation, or to only recover respectively as much electrical output as the battery is able to receive, and to extract the excess kinetic energy from the vehicle by means of a non-recovering brake, typically a friction brake. For this, however, it is necessary to dimension the brake sufficiently for the quantities of heat which are to be expected, i.e. a brake is required which is larger and more expensive than one which only has to receive an energy excess which is not to be managed through recovery at full power.
It is an object of the invention to create, for a motor vehicle with a chassis, an electric motor for driving the chassis, a battery and an inverter, which is optionally operable, in order to drive the electric motor with energy from the battery or to charge the battery with electrical energy extracted from the movement of the motor vehicle, a method for recovery electrical energy, which is able to be applied independently of the equipping of the motor vehicle with electrical consumers, in order to remove recovered energy which can not be received by the vehicle battery.
The problem is solved according to an aspect of the invention by a method with the steps: determining a deceleration requested - e.g. by a driver through actuating a brake pedal determining a present power consumption capacity of the inverter; and controlling the efficiency of the inverter by means of the present power consumption capacity and the requested deceleration.
By the method according to the invention, kinetic energy of the vehicle, which can not be received by the battery, is released as thermal energy in the inverter. As the inverter is required in any case for operating the electric motor, the method is able to be applied in every electrically driven motor vehicle, without additional consumers being required.
According to the current state of the art, the deceleration which his able to be achieved through recovery can not render superfluous a brake dissipating the received kinetic energy. If, however, such a brake must be present in the vehicle, it can be expediently integrated into the method according to the invention, by the controlling of the efficiency taking place furthermore taking into consideration a power consumption capacity of the brake.
In the simplest case, the present power consumption capacity of the inverter can be assumed to be equal to that of the battery; however, this has the result that the deceleration which is able to be achieved is systematically estimated too low, as losses in the inverter remain unconsidered. It is therefore preferred to take into consideration the efficiency of the inverter in the estimation. In most application situations, the aim is to recover as much kinetic energy of the vehicle as possible and, for this, to operate the inverter under conditions in which it has an optimal efficiency; accordingly, the power consumption capacity of the inverter can be estimated as a product of the present power consumption capacity of the battery and of the optimal efficiency of the inverter. Precisely in the application situation which is considered here, in which the battery can not receive the entire current which the inverter could deliver at optimal efficiency, and it is therefore operated with suboptimal efficiency, for an estimation of the power consumption capacity of the inverter which is close to reality, the present efficiency of the inverter should be taken into consideration.
The controlling of the efficiency can comprise: setting an optimal efficiency, when the power consumption capacity of the inverter, if applicable plus a power consumption capacity of the brake, is sufficient in order to provide the requested deceleration, and/or setting a suboptimal efficiency, when the power consumption capacity of the inverter, if applicable plus a power consumption capacity of the brake, is not sufficient in order to provide the requested deceleration, and/or raising the efficiency of the inverter, when the power consumption capacity of the inverter, if applicable plus a power consumption capacity of the brake, is sufficient in order to provide the requested deceleration, and/or reducing the efficiency of the inverter, when the power consumption capacity of the inverter, if applicable plus a power consumption capacity of the brake, is not sufficient in order to provide the requested deceleration.
In order to influence the efficiency of the inverter, in particular its switching frequency can be changed. The higher this is, the more current flow is required in the inverter, in order charge and discharge capacities; this current flow generates heat and reduces the efficiency.
Techniques for determining the present power consumption capacity of a battery are known per se and are described in the document DE 102021 211 722.8 cited in the introduction; as explained above, these can be converted into the power consumption capacity of the inverter. As output data for the determining, accordingly a charging current, a charging voltage, a charging output or generally a measurement variable, which enables a conclusion concerning the internal resistance of the battery, and/or of a temperature of the battery, can be referred to. In order to determine a present power consumption capacity of the brake, its temperature can be measured; by means of a known thermal capacity of the brake, it can then be estimated how much energy the brake can still receive before it reaches a temperature at which damage can occur, or a correct braking function is no longer guaranteed. Alternatively, the temperature of the brake can also be estimated by means of past braking performances.
Conversely, the output which must be received by the brake can also be dictated by a possibly necessary protection of the inverter from overheating. As damage to the inverter can make driving impossible and is generally expensive to rectify, if necessary an increased wear of the brake can be accepted for protection of the inverter. For this reason, the determining of the present power consumption capacity of the brake can comprise the measuring of a temperature of the inverter or the estimating of the temperature of the inverter by means of past efficiencies. Thus, by the power consumption capacity of the brake being set higher if necessary, an overheating of the inverter can be prevented.
According to a further aspect of the invention, the problem is solved by a motor vehicle with a chassis, an electric motor for driving the chassis, a battery and an inverter, which is optionally operable in order to drive the electric motor with energy from the battery, or to charge the battery with energy extracted from the movement of the motor vehicle, a dissipative brake and a control unit, wherein the control unit is configured to carry out the method which is described above.
An object of the invention, furthermore, is a computer program product with program code means which enable a computer to carry out the method which is described above, or to operate as control unit in the motor vehicle which is mentioned above.
Further features and advantages of the invention will emerge from the following description of example embodiments with reference to the attached figures. There are shown:
Fig. 1 a block diagram of a motor vehicle; and
Fig. 2 a flow diagram of an operating method of the control unit of the motor vehicle of Fig. 1. Figure 1 shows schematically a motor vehicle with an electric motor 1, which drives wheels of a chassis 3 via transmission 2. As assistance for the electric motor 1, a combustion engine 4 can be provided. An inverter 5 supplies the electric motor 1 in motor operation with electrical energy from a battery 6; the inverter 5 also assists a generator operation, in which the battery 6 is charged with current from the electric motor 1. A further converter 7 can be provided, in order to supply various electrical consumers of the vehicle which are known perse and are not described here. A charging interface 8 serves for the re-charging of the battery 6 from an external energy source.
A control unit 9 is connected to an accelerator pedal 10, in order to detect an acceleration of the vehicle requested by a driver, and in order to control the inverter
5 so that the electric motor 1, if applicable assisted by the combustion engine 4, which is likewise subject to the control unit 9, delivers the desired, or, if the motor 1 is not powerful enough for this, the maximum acceleration which is able to be reached.
In a corresponding manner, the control unit 9 is connected to a brake pedal 11 , in order to detect a desired deceleration and to control the inverter 5 and brakes 12 of the vehicle in a suitable manner for producing this deceleration. In order to be able to recover here as much kinetic energy as possible which is extracted from the vehicle, the control unit 9 must take into consideration how much electrical output the battery 6 can receive in its present charging state. For this, the control unit 9 is connected to a charge state sensor 13, which estimates and emits a charge state of the battery 6 in any known manner, whether by measuring a battery internal resistance, of charging current and charging voltage, or by integration of current flows from and to the battery 6, and has e.g. a lookup table or a programmed calculation specification, which specifies a maximum charging current for the battery
6 for the present charge state of the battery 6, if applicable as a function of a temperature measured by a sensor 14 at the battery 6.
Fig. 2 shows by means of a flow diagram an operating method of the control unit 9, repeated at regular time intervals, typically several times during an actuation of the brake pedal 11. In step S1 the charge state of the battery 5 is updated by means of data of the sensor 13, and a maximum permissible charging current lmax is determined for this charge state (and if applicable the present temperature of the battery 5).
In step S2, the brake pedal 11 is interrogated for a desired deceleration atarget.
Step S3 calculates by means of the mass and the present speed of the vehicle a braking power Ptarget necessary for the desired deceleration atarget. This can be converted by means of wherein II designates the battery voltage and q designates the present efficiency of the inverter 5, into a charging current Itarget, which would result if the desired deceleration atarget were generated solely through recuperation operation of the inverter 5.
When ltarget<lmax (S4), the desired deceleration can be achieved through recuperation operation, with maintaining of the efficiency q (S5), and the control unit controls the inverter 5 accordingly, but leaves the brakes 12 unactuated.
In the opposite case, the control unit 9 checks whether the brakes 12 are to be referred to in a supporting manner, or whether the efficiency of the inverter 5 can and is to be reduced. Various strategies are conceivable here, e.g. in this case, the brakes 12 are referred to (S6), in order to contribute the entire difference between the requested deceleration and that which the inverter can provide with a maintaining of the efficiency r|, until in step S7, through direct measuring or through calculating by means of a thermal model of the brakes 12 and the friction heat released therein during the braking process, a critical heating of the brakes 12 is detected. At the latest, the control unit 9 then increases the clock rate f of the inverter 5 (S8), in order to set in this way a lower efficiency r|’ of the inverter. As can be seen from the above formula, this has the result that the mechanical output which the electric motor 1 receives, in order to generate the maximum permissible charging current lmax, increases. Thus, the brakes can be relieved with unchanged deceleration. Alternatively, in the case where in step S4 ltarget<lmax, the control unit can directly set the lower efficiency (S8) and can only then refer to the brakes if otherwise the inverter is threatening to overheat, or in this case at the same time the brakes can be referred to, and the efficiency of the inverter can be reduced.
When the inverter 9 operates with reduced efficiency, it is expedient to also monitor its temperature and to check (S9) whether an upper threshold of the permissible operating temperature is reached. If this is the case, the efficiency is raised again (S10), and the contribution of the brakes to the deceleration of the vehicle is increased.
The efficiency which is set at the end of the method described above can be used as initial value of the efficiency in a subsequent iteration of the method; thus, the efficiency can be reduced successively in the course of several repetitions of the step S8 (or in several repetitions of the step S10 can be brought closer again successively to the optimal value). Such a successive changing can consist in that in each performance of step S8 the clock frequency f is multiplifed with a predetermined factor >1 , and in S10 is divided by the same or another factor. Alternatively, the factor can be selected as a function of the difference Itarget-lmax, in order to arrive at a suitable value of the efficiency in the course of few iterations.
Alternatively, each time when step S10 is performed, the optimal efficiency can be set immediately, in order to quickly reduce the release of heat in the inverter.
Furthermore, alternatively at the start of each iteration of the method, the optimal value of the efficiency can be set anew as efficiency r|.
Reference numbers
1 electric motor
2 transmission 3 chassis
4 combustion engine
5 inverter
6 battery
7 converter 8 charging interface
9 control unit
10 accelerator pedal
11 brake pedal
12 brake 13 charge state sensor
14 temperature sensor

Claims

C L A I M S
1. A method for recovering electrical energy in a motor vehicle, wherein the motor vehicle comprises a chassis (3), an electric motor (1) for driving the chassis (3), a battery (6) and an inverter (5), which is optionally operable in order to drive the electric motor (1) with energy from the battery (6) or to charge the battery (6) with energy extracted from the movement of the motor vehicle, with the steps: determining (S2) a requested deceleration (atarget); determining a present power consumption capacity of the inverter (5); and controlling (S8) the efficiency of the inverter (5) by means of the present power consumption capacity and the requested deceleration.
2. The method according to Claim 1, in which the motor vehicle has furthermore a dissipative brake (12), in which the controlling of the efficiency takes place furthermore taking into consideration a power consumption capacity of the brake (12).
3. The method according to Claim 1 or 2, in which the determining of the present power consumption capacity of the inverter (5) comprises the calculating of the power consumption capacity of the inverter by means of a present power consumption capacity of the battery (lmax) and of the present efficiency (r|, r|’) of the inverter or by means of the present power consumption capacity of the battery (lmax) and of an optimal efficiency (q) of the inverter.
4. The method according to Claim 1 , 2 or 3, in which the controlling of the efficiency comprises: setting an optimal efficiency when the power consumption capacity of the inverter, if applicable plus a power consumption capacity of the brake (12), is sufficient in order to provide the requested deceleration, and/or setting a suboptimal efficiency when the power consumption capacity of the inverter, if applicable plus the power consumption capacity of the brake (12), is not sufficient in order to provide the requested deceleration, and/or raising the efficiency of the inverter when the power consumption capacity of the inverter, if applicable plus a power consumption capacity of the brake (12), is sufficient in order to provide the requested deceleration, and/or reducing the efficiency of the inverter when the power consumption capacity of the inverter, if applicable plus the power consumption capacity of the brake (12), is not sufficient in order to provide the requested deceleration.
5. The method according to one of the preceding claims, in which the controlling of the efficiency (S8, S10) comprises the changing of the switching frequency of the inverter.
6. The method according to one of the preceding claims, in which the determining of the present power consumption capacity of the inverter comprises the determining of a charge state, of a charging current or of a charging voltage and/or of a temperature of the battery.
7. The method according to one of the preceding claims, in so far as referred back to Claim 2, in which the determining of the present power consumption capacity of the brake comprises the measuring of a temperature of the brake or the estimating of the temperature of the brake (S7), in particular by means of past brake performances.
8. The method according to one of the preceding claims, in so far as referred back to Claim 2, in which the determining of the present power consumption capacity of the brake comprises the measuring of a temperature of the inverter or the estimating of the temperature of the inverter by means of past efficiencies (S9).
9. A motor vehicle with a chassis (3), an electric motor (1) for driving the chassis (1), a battery (6) and an inverter (5), which is optionally operable in order to drive the electric motor (1) with energy from the battery (6) or to charge the battery (6) with energy extracted from the movement of the motor vehicle, and a control unit (9), characterized in that the control unit (9) is configured to carry out the method according to one of the preceding claims.
10. A computer program product with program code means, which enable a computer to carry out the method according to one of Claims 1 to 7 or to operate as control unit in the motor vehicle according to Claim 8.
EP24700882.4A 2023-02-10 2024-01-11 Method for recovering electrical energy and motor vehicle equipped for this Pending EP4662083A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102023201090.9A DE102023201090A1 (en) 2023-02-10 2023-02-10 Method for recuperating electrical energy and motor vehicle equipped therefor
PCT/EP2024/050539 WO2024165260A1 (en) 2023-02-10 2024-01-11 Method for recovering electrical energy and motor vehicle equipped for this

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KR101142361B1 (en) * 2006-08-07 2012-05-18 주식회사 만도 Control method for traction control system
DE102016206621A1 (en) * 2016-04-19 2017-10-19 Bayerische Motoren Werke Aktiengesellschaft Method and device for operating an electric and / or hybrid vehicle, computer program and computer program product
KR102417517B1 (en) * 2016-11-24 2022-07-05 현대자동차주식회사 Method for controlling motor system
DE102020133118A1 (en) * 2020-12-11 2022-06-15 Man Truck & Bus Se Method and device for providing a storage capacity reserve in a traction battery for an upcoming downhill drive
EP4079563A1 (en) * 2021-04-20 2022-10-26 Volvo Truck Corporation A control interface for inefficient electric machines
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