DE102020200916A1 - Method for maximizing recuperation energy when braking a vehicle with an electrical machine and braking device for braking a vehicle with an electrical machine - Google Patents

Abstract

The present invention creates a method for maximizing recuperation energy when braking a vehicle with an electrical machine (EM), comprising a recognition (S1) of a need for a braking intervention when the vehicle is in operation; a determination (S2) of data about the surroundings of the vehicle and / or the vehicle itself and / or the electrical machine (EM) during the braking intervention; an assessment (S3) of the recuperation energy that can be generated by braking during the braking intervention based on the determined data; a determination (S4) of an optimal braking profile for a braking intensity and / or for a braking effect over time for the braking intervention in such a way that the recuperation energy is maximized during the optimal braking profile; and an automatic implementation (S5) of the braking intervention in accordance with the optimal braking profile.

Description

The present invention relates to a method for maximizing recuperation energy when braking a vehicle with an electrical machine and a braking device for braking a vehicle with an electrical machine.

State of the art

In vehicles with an electric traction drive, similar to vehicles with internal combustion engines, a deceleration can be brought about by a pedal movement, in particular by releasing an accelerator pedal and / or by pressing a brake pedal. When reducing the speed of a vehicle with an electric motor, kinetic energy can be converted into electrical energy or recovered and stored in a battery, for example. This process is also described as recuperation. If the driver uses the pedal directly while the vehicle is in operation, the driver can usually only assess the recuperation behavior of the electric motor and other components in the vehicle or the electric motor with difficulty and it is difficult to adapt the deceleration behavior to a desired energy maximization.

In the US 2016/243962 describes a method with two braking modes for a vehicle with an electric traction drive, in which the driver actuates the accelerator pedal himself.

Disclosure of the invention

The present invention provides a method for maximizing recuperation energy when braking a vehicle with an electric machine according to claim 1 and a braking device for braking a vehicle with an electric machine according to claim 11.

Preferred further developments are the subject of the subclaims.

Advantages of the invention

The idea on which the present invention is based is to bring about a deceleration in a vehicle with an electric traction drive, which is automatically triggered and takes place without actuation by the driver and thus a deceleration can be adapted in such a way that it leads to maximum recuperation energy and for this can take into account the states and efficiencies of the subsystems involved.

According to the invention, in the method for maximizing recuperation energy when braking a vehicle with an electrical machine, a need for a braking intervention is recognized when the vehicle is in operation; determining data about the surroundings of the vehicle and / or the vehicle itself and / or the electrical machine during the braking intervention; an assessment of the recuperation energy that can be generated by braking during the braking intervention based on the determined data; determining an optimal braking profile for a braking intensity and / or for a braking effect over time for the braking intervention in such a way that the recuperation energy is maximized during the optimal braking profile; and an automatic implementation of the braking intervention according to the optimal braking profile.

The vehicle advantageously comprises an electric traction drive, for example a purely electrically operated vehicle or a hybrid vehicle, preferably with a powerful electric motor, in order to generate sufficient deceleration. The traction drive can comprise an electrical machine, which can furthermore comprise power electronics with an inverter and a control device and an electrical energy storage device, for example a battery. To generate recuperation energy, the electrical machine can be operated as a generator and feed electrical energy into the system of the traction drive or the vehicle. The generated recuperation energy can only be fed into the system of the traction drive or the vehicle if it can also absorb electrical energy. For this purpose, the energy must be able to be absorbed by an energy storage device or a consumer.

The system of the traction drive or of the vehicle can be set up to absorb such energy by including a corresponding energy storage device and / or a local electrical consumer, for example an air conditioning system. The generated amount of recuperation energy can be monitored and / or estimated (predicted). Here, it can be taken into account, for example, how much recuperation energy will be generated when the journey continues. The efficiencies and / or operating states of the subsystems involved, such as the inverter or the state of charge and the capacity of the energy storage device or the consumer, can be taken into account and estimated. The course of the journey itself and parameters influencing it, such as a speed profile based on known or recognized inclines and declines, can be included in the assessment of the energy generated in the near future. The course of the journey can be through visual sensors or Position systems (such as GPS or similar) are supported.

The braking process can be optimal if the maximum recuperation energy that can be achieved or that can be stored or consumed for the respective driving or operating state can be generated. In other words, the deceleration can be limited in such a way that only as much recuperation energy is generated as can be absorbed by the traction drive system or the vehicle.

If the braking is purely electrical, the optimized braking process must be adapted to comply with safety standards, with sufficient braking force being able to be generated in order to be able to meet the deceleration profiles estimated or recognized from the upcoming journey, which are necessary for the intended journey are. If safe braking from electrical braking alone can no longer be guaranteed even with appropriate adjustment of the recuperation energy, a friction brake can also be used in the vehicle to increase the braking effect and make braking safer and reduce the likelihood of a collision with an obstacle or for to reduce an uncontrollable driving process.

Automation of the deceleration process can thus help the system of the vehicle, for example through a control device, to maximize the energy to be recuperated and, in addition, the operating modes and states as well as the efficiencies for consumption and their operation of the subsystems such as the energy absorption device, the inverter, the electrical machine, the transmission or influencing variables for the generation of the recuperation energy, such as the efficiency of the machine, the vehicle weight, the road condition, the inclination of the road, the environmental conditions and / or the existing traffic or others can estimate or recognize and take into account.

According to a preferred embodiment of the method, a minimum and / or a maximum braking intensity are determined for the optimal braking process.

In this case, the method can be designed to generate a braking process when approaching an obstacle or, for example, a traffic light in such a way that the deceleration only occurs shortly before the obstacle or the traffic light, for example on the remaining 10% of the way after the obstacle has been recognized or the traffic light. The maximum braking intensity can be designed accordingly for this purpose. The minimum and / or maximum braking intensity can be designed depending on the demands on the driving comfort during the deceleration and correspond to the fulfillment of the predetermined driving comfort.

A driver can transmit and / or save his comfort settings to the control device via an interface or via a data transfer, for example via a personalized data record. The degree of efficiency relating to the maximization of the recuperation energy can also be adapted to this and the maximization can be somewhat lower in the case of less braking.

The minimum braking intensity can be selected or predetermined in such a way that a safety standard that is at least to be complied with can be met for an at least achievable braking performance. The minimum braking intensity can furthermore be selected or predetermined in such a way that a minimum safety distance from a vehicle traveling ahead can be maintained.

The minimum and / or maximum braking intensity can also be adapted to the traffic situation, the topography of the roadway and / or weather conditions and comply with a specification of maximizing the recuperation energy, driving comfort, the safety specifications and safety distances.

The traffic situation can be determined and observed via a sensor system, for example front and / or rear cameras and / or radar sensors and / or ultrasonic sensors. It can be specified here that the vehicle can swim with traffic and the braking process can be adapted in such a way that a perceived obstruction to other road users can be reduced or even prevented.

According to another scenario, after recognizing an obstacle or a traffic light, the deceleration can take place immediately and gently, i.e. with a lower intensity than when braking only directly in front of the obstacle or the traffic light, whereby the minimum and / or maximum braking intensity can be set accordingly, for example by a control device. Such automatic target braking in front of an obstacle and / or a traffic light can be more efficient, more comfortable and / or safer than if it is carried out by a driver himself.

According to a preferred embodiment of the method, the data about the surroundings of the vehicle and / or about the vehicle itself and / or about the electrical machine are determined via a sensor device during the braking intervention and / or are in a memory device stored and / or can at least be called up by a control device.

The storage device can be located on board the vehicle or at least connected to it via a data communication platform (such as a cloud). The control device in the vehicle can advantageously calculate an optimal braking trajectory and implement it within given limits. This can vary from driving situation to driving situation and can be recognized and taken into account accordingly.

The braking trajectory as the braking course can advantageously correspond to the energetically optimal deceleration course. This can advantageously be independent of the selection of the optimization algorithm and a wide variety of mathematical methods can be used. The control device can be a central control device in the vehicle, which can access data for the momentary assessment of the efficiency of the electric traction drive. These data can be stored in the control device and / or memory device. The control device can also comprise the storage device itself.

According to a preferred embodiment of the method, the data include a state of charge of the battery and / or an efficiency map of the battery and / or an efficiency map of an inverter and the electrical machine and / or a driving resistance value of the vehicle and / or occurring on-board network loads and / or a topology of the driving terrain .

The efficiency map of the battery can have an efficiency as a function of the current and / or the state of charge and / or the temperature and / or the aging state of the battery. The efficiency map of an inverter and the electrical machine can have an efficiency as a function of the torque and / or the speed and / or the temperature of the machine or the inverter.

The driving resistance of the vehicle can be based on rolling resistance and / or air resistance. These efficiency maps and / or driving resistances of the vehicle can be permanently stored in the memory device or can be determined adaptively (online) by sensors or by the control device itself. This can be connected to appropriate sensors for this purpose. For example, a learning function can also be present and used in the control device and / or an external control or a computer, which can be implemented, for example, by direct observation (online observation) of coasting processes and / or deceleration and / or acceleration processes and a subsequent parameter estimation can determine or estimate the driving resistance values of the vehicle.

A current gradient can be determined by a navigation system and / or suitable map material and / or by acceleration sensors and can be taken into account for the recuperation energy estimate that can be generated.

According to a preferred embodiment of the method, an obstacle or a traffic light circuit with a sensor device is recognized as the necessity for a braking intervention and the braking intensity is regulated in such a way that it always remains lower than a predetermined value.

In this way, the braking intensity in front of an obstacle or a traffic light switch can be kept below a comfort limit and / or below an operating limit, the operating limit ensuring that the recuperation energy can be kept below a certain limit, since the battery in the vehicle, for example, cannot currently consume high power or the inverter just needs to be spared or because an efficiency optimum can exist for the entire electric drive train at such a limit.

According to a preferred embodiment of the method, an operating limit for an inverter and / or a battery is recognized or is stored in the memory device and is taken into account for determining an optimal braking profile.

Furthermore, current on-board network loads on a high-voltage side and / or low-voltage side of the drive train can be monitored and loads can be switched on via which the recuperation energy can be absorbed, so that the energy does not need to be fed into the battery or energy absorption device.

According to a preferred embodiment of the method, a friction brake and / or a hydraulic braking process is actuated for target braking or for braking assistance for recuperation braking.

According to a preferred embodiment of the method, an energy expenditure for an automatic activation of the braking assistance by a friction brake and / or a hydraulic braking process is taken into account for the optimal braking process.

According to a preferred embodiment of the method, the driver specifies a wish for a maximum deceleration of the vehicle by the braking intervention and is taken into account and / or implemented.

A transition from electrical braking to auxiliary braking, such as target braking, by means of a friction brake, such as hydraulic, can also be designed to be energy-efficient with regard to recuperation. For example, the energy expenditure for an automatic activation of the braking system, for example by an ESP hydraulic pump (electronic safety program for slip control or individual wheel braking), can be taken into account in the overall energy optimization.

According to a preferred embodiment of the method, the electric machine comprises a battery, an inverter and an electric motor.

According to the invention, a braking device for braking a vehicle with an electrical machine comprises a control device in the vehicle or is connected to the vehicle, which is connected to the electrical machine and to a sensor device and is set up to maximize recuperation energy when braking the vehicle, the The control device is also set up to recognize a need for a braking intervention during operation of the vehicle; To determine data about the surroundings of the vehicle and / or the vehicle itself and / or the electrical machine during the braking intervention; to assess the recuperation energy that can be generated by braking during the braking intervention based on the determined data; to determine an optimal braking curve for a braking intensity and / or for a braking effect over time for the braking intervention in such a way that the recuperation energy is maximized during the optimal braking curve; and to carry out the braking intervention automatically according to the optimal braking curve.

According to a preferred embodiment of the braking device, the electric machine comprises a battery, an inverter and an electric motor.

The method can also be distinguished by the features mentioned in connection with the braking device and their advantages, and vice versa.

Further features and advantages of embodiments of the invention emerge from the following description with reference to the accompanying drawings.

Figure list

The present invention is explained in more detail below with reference to the exemplary embodiment indicated in the schematic figures of the drawing.

• 1 eine schematische Darstellung einer Bremseinrichtung zum Bremsen eines Fahrzeugs mit einer elektrischen Maschine gemäß einem Ausführungsbeispiel der vorliegenden Erfindung;
• 2 eine schematische Darstellung einer Steuereinrichtung in einer Bremseinrichtung gemäß einem Ausführungsbeispiel der vorliegenden Erfindung; und
• 3 eine Blockdarstellung von Verfahrensschritten eines Verfahrens zum Maximieren einer Rekuperationsenergie beim Bremsen eines Fahrzeugs mit einer elektrischen Maschine gemäß einem Ausführungsbeispiel der vorliegenden Erfindung.

Show it:

• 1 a schematic representation of a braking device for braking a vehicle with an electrical machine according to an embodiment of the present invention;
• 2 a schematic representation of a control device in a braking device according to an embodiment of the present invention; and
• 3 a block diagram of method steps of a method for maximizing a recuperation energy when braking a vehicle with an electrical machine according to an embodiment of the present invention.

In the figures, identical reference symbols denote identical or functionally identical elements.

1 shows a schematic representation of a braking device for braking a vehicle with an electrical machine according to an embodiment of the present invention.

In the 1 becomes a vehicle F. shown in which a braking device 10 to brake the vehicle F. with an electric machine EM is available. The braking device 10 comprises a control device SE in the vehicle, which with the electric machine EM and with a sensor device S. is connected and is set up to maximize a recuperation energy when braking the vehicle, wherein the control device is further set up to recognize a need for a braking intervention during operation of the vehicle; Data about the surroundings of the vehicle and / or the vehicle itself and / or the electrical machine EM to determine during the braking intervention; to assess the recuperation energy that can be generated by braking during the braking intervention based on the determined data; to determine an optimal braking curve for a braking intensity and / or for a braking effect over time for the braking intervention in such a way that the recuperation energy is maximized during the optimal braking curve; and to carry out the braking intervention automatically according to the optimal braking curve.

The electric machine EM can drive a traction drive, which is done by the control device SE can be controlled. the Sensor device S. can recognize a topology of the roadway and / or collect visual data (or from radar) about obstacles, traffic lights, weather conditions or other information. The control device SE can alternatively also be arranged outside the vehicle, for example connected to a data server to which the vehicle can also be connected (not shown).

A friction brake can also be used RB on one or more or on all wheels of the vehicle F. to be available.

Through the sensor device S. the end of a traffic jam or a red traffic light can be recognized.

2 shows a schematic representation of a control device in a braking device according to an embodiment of the present invention.

The control device SE can be beneficial with the inverter INV , the electrical machine, such as an electric motor EMT the electrical machine, and an energy storage device Batt and also with a sensor device S. be connected. In this way, the machine and / or the inverter INV and / or the energy storage device Batt, for example the state of charge thereof, can be determined and monitored over a period of time.

The energy storage device Batt can include at least one battery. This makes it possible to advantageously estimate whether and how much energy the energy storage device can absorb at the moment or in the near future. Based on this and on the operating data of the mode of operation of the inverter and the electrical machine, it can consequently be determined how much recuperation energy can be absorbed in the system.

In this way, the control unit can collect the relevant information such as the efficiency of the inverter, battery, machine, vehicle weight, etc. and determines the Pareto-optimal deceleration profile in order to recuperate as much energy as possible while at the same time complying with other boundary conditions such as safety and comfort. In this case, a specification can be set according to which the driving trajectory does not run too slowly to be a traffic obstacle, and also not too abruptly so as not to shake the occupants, that is, to maintain a certain level of comfort.

The driver himself does not need to intervene in the brakes and can be informed about the automatic mode via an information system (display). If the battery cannot absorb any recuperation energy, the friction brakes are automatically activated to ensure safe braking. A prerequisite may be that the vehicle has sufficient environment recognition to be able to reliably display the function.

With an assessment of the recuperation energy that can be generated by braking during the braking intervention, an optimal braking process for a braking intensity and / or for a braking effect over time for the braking intervention can be determined in such a way that the recuperation energy is maximized during the optimal braking process. The control device SE can then automatically perform a braking intervention according to the optimal braking process and adapted to the situation.

3 shows a block diagram of method steps of a method for maximizing a recuperation energy when braking a vehicle with an electrical machine according to an embodiment of the present invention.

In the method for maximizing recuperation energy when braking a vehicle with an electrical machine, recognition takes place S1 a need for a braking intervention during operation of the vehicle; a determination S2 of data about an environment of the vehicle and / or the vehicle itself and / or the electrical machine during the braking intervention; a judging S3 the recuperation energy that can be generated by braking during the braking intervention based on the determined data; a determining S4 an optimal braking profile for a braking intensity and / or for a braking effect over time for the braking intervention in such a way that the recuperation energy is maximized during the optimal braking profile; and automatic execution S5 of the braking intervention according to the optimal braking process.

Although the present invention has been fully described above on the basis of the preferred exemplary embodiment, it is not restricted thereto, but rather can be modified in many different ways.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 2016243962 [0003]

Claims (12)

Method for maximizing recuperation energy when braking a vehicle with an electric machine (EM) comprising the steps: - Recognition (S1) of a need for a braking intervention during operation of the vehicle; - Determination (S2) of data about an environment of the vehicle and / or the vehicle itself and / or the electrical machine (EM) during the braking intervention; - Assessment (S3) of the recuperation energy that can be generated by braking during the braking intervention based on the determined data; - Determination (S4) of an optimal braking profile for a braking intensity and / or for a braking effect over time for the braking intervention in such a way that the recuperation energy is maximized during the optimal braking profile; and - Automatic implementation (S5) of the braking intervention according to the optimal braking process. Procedure according to Claim 1 , in which a minimum and / or a maximum braking intensity are determined for the optimal braking process. Method according to one of the Claims 1 or 2 , in which the data about the surroundings of the vehicle and / or about the vehicle itself and / or about the electric machine (EM) are determined via a sensor device during the braking intervention and / or are stored in a memory device and / or at least by a control device (SE) are available. Procedure according to Claim 3 , in which the data include a charge status of the battery and / or an efficiency map of the battery and / or an efficiency map of an inverter and the electrical machine and / or a driving resistance value of the vehicle and / or occurring on-board network loads and / or a topology of the driving terrain. Method according to one of the Claims 1 until 4th , in which an obstacle or a traffic light circuit with a sensor device is recognized as a necessity for a braking intervention and the braking intensity is regulated in such a way that it always remains lower than a predetermined value. Method according to one of the Claims 1 until 5 , at which an operating limit for an inverter and / or a battery is recognized or is stored in the memory device and is taken into account for determining an optimal braking curve. Method according to one of the Claims 1 until 6th , in which a friction brake and / or a hydraulic braking process is actuated for target braking or for braking assistance for recuperation braking. Procedure according to Claim 7 , in which an energy expenditure for an automatic activation of the braking assistance by a friction brake and / or a hydraulic braking process is taken into account for the optimal braking process. Method according to one of the Claims 1 until 8th , in which a desired specification of the driver for a maximum deceleration of the vehicle by the braking intervention takes place and is taken into account and / or implemented. Method according to one of the Claims 1 until 9 , in which the electric machine (EM) comprises a battery, an inverter and an electric motor. Braking device (10) for braking a vehicle (F) with an electrical machine (EM) comprising - A control device (SE) in the vehicle (F) or connected to the vehicle (F), which is connected to the electrical machine (EM) and to a sensor device (S) and is set up to maximize recuperation energy when braking the vehicle , wherein the control device is further configured to recognize a need for a braking intervention during operation of the vehicle; Determine data about the surroundings of the vehicle and / or the vehicle itself and / or the electrical machine (EM) during the braking intervention; to assess the recuperation energy that can be generated by braking during the braking intervention based on the determined data; to determine an optimal braking curve for a braking intensity and / or for a braking effect over time for the braking intervention in such a way that the recuperation energy is maximized during the optimal braking curve; and to carry out the braking intervention automatically according to the optimal braking curve. Braking device (10) after Claim 11 , in which the electric machine (EM) comprises a battery, an inverter and an electric motor.

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