Method for maximizing recuperation energy during vehicle braking and braking device for vehicle braking

Abstract

The present invention provides a method for maximizing recuperation energy when braking a vehicle having an electric motor (EM), the method comprising the following steps: identifying (S1) the need for a braking intervention when the vehicle is running; acquiring (S2) data about the vehicle's environment and / or the vehicle itself and / or the electric motor (EM) during the braking intervention; evaluating (S3) the recuperation energy that can be generated by braking during the braking intervention based on the acquired data; determining (S4) an optimal braking curve for the braking intensity and / or for a temporary braking effect for the braking intervention so as to maximize the recuperation energy with an optimal braking curve; and automatically performing (S5) the braking intervention according to the optimal braking curve.

Description

Technical Field

[0001] The invention relates to a method for maximizing recuperation energy when braking a vehicle having an electric machine and to a braking device for braking a vehicle having an electric machine. Background Art

[0002] For vehicles with electric traction drives, similar to vehicles with combustion engines, deceleration can be brought about by pedal movements, in particular by moving the accelerator pedal backwards and / or by actuating the brake pedal. When reducing the driving speed of a vehicle with an electric motor, kinetic energy can be converted into electrical energy or recovered and stored, for example, in a battery. This process is also described as recuperation. If the pedal movement is actuated directly by the driver while the vehicle is in motion, it is usually difficult for the driver to estimate the recuperation state of the electric motor and other components in the vehicle or the electric motor and to adapt the deceleration state to the desired energy maximization.

[0003] US 2016 / 243962 describes a method having two braking modes for a vehicle having an electric traction drive, for which the driver personally actuates the accelerator pedal. Summary of the invention

[0004] The present invention provides a method for maximizing recuperation energy when braking a vehicle having an electric machine and a braking device for braking a vehicle having an electric machine.

[0005] Preferred developments are the subject matter of the dependent claims.

[0006] The idea underlying the present invention is to cause a deceleration of a vehicle having an electric traction drive, which is triggered automatically and takes place without an operation by the driver and which can thus be adjusted in such a way that it causes maximum recuperation of energy and for this purpose the states and efficiencies of the involved subsystems can be taken into account.

[0007] According to the present invention, in a method for maximizing recuperation energy when braking a vehicle having an electric motor, the necessity for a braking intervention while the vehicle is running is identified; data about the vehicle's environment and / or the vehicle itself and / or the electric motor are acquired during the braking intervention; the recuperation energy that can be generated by braking during the braking intervention is evaluated based on the acquired data; an optimal braking curve for braking intensity and / or for a temporary braking effect is determined for the braking intervention so that the recuperation energy is maximized with the optimal braking curve; and the braking intervention is automatically performed according to the optimal braking curve.

[0008] The vehicle advantageously comprises an electric traction drive, such as a purely electrically operated vehicle or a hybrid vehicle, which preferably has a powerful electric motor in order to produce sufficient deceleration. The traction drive can comprise an electric machine, which can further comprise power electronics with an inverter and a control device and an electric energy storage device, such as a battery. In order to generate recuperation energy, the electric 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 if the system of the traction drive or the vehicle can also absorb electrical energy. For this purpose, the energy must be able to be absorbed by the energy storage device or the load.

[0009] The traction drive or the system of the vehicle can be set up for such energy absorption by including a corresponding energy storage device and / or a local electrical load, such as an air conditioner. The amount of recuperation energy generated can be monitored and / or estimated (predicted). Here, for example, it can be taken into account how much recuperation energy will be generated during continued driving. Here, the efficiency and / or operating state of the participating subsystems, such as the inverter, or the charge state and absorption capacity of the energy storage device or load can be taken into account and estimated. The process of the driving itself and the influencing parameters for the driving, such as the speed distribution caused by known or identified uphill and downhill slopes, can flow into the estimation of the energy generated in the near future. The process of the driving can be supported by visual sensors or position systems (such as GPS or similar systems).

[0010] The braking curve can be optimized if the maximum achievable or storable or consumable recuperation energy can be generated for the respective driving or operating state. In other words, the deceleration can be limited so that only as much recuperation energy is generated as can be absorbed by the traction drive or the vehicle's system.

[0011] If the braking is performed purely electrically, an optimized braking curve must be set to comply with safety standards, wherein sufficient braking force can be generated to achieve the deceleration profile estimated or identified from the expected driving and necessary for the set driving process. If safe braking is no longer guaranteed by electric braking alone when the recuperation energy is appropriately adjusted, the friction brakes in the vehicle can be used additionally to increase the braking effect and make braking safer and reduce the possibility of collision with obstacles or the possibility of uncontrollable driving processes.

[0012] The automation of the deceleration process can thus contribute to the following goal: the system of the vehicle, for example through a control device, can maximize the energy to be recovered and for this purpose can estimate or identify and take into account the operating mode and state of the subsystem and the efficiency of the load and its operation, such as the operating mode and state of the energy absorption device, inverter, electric machine, transmission or influencing variables for the generation of recovered energy, such as the efficiency of the electric machine, vehicle weight, roadway conditions, roadway inclination, environmental conditions and / or existing traffic or other influencing variables.

[0013] According to a preferred specific embodiment of the method, a minimum and / or maximum braking intensity is determined for an optimal braking curve.

[0014] In this case, the method can be designed to generate a braking profile when approaching an obstacle or, for example, a traffic light so that deceleration does not begin until shortly before the obstacle or traffic light, for example, at the remaining 10% of the distance after the obstacle or traffic light has been detected. For this purpose, the maximum braking intensity can be designed accordingly. The minimum and / or maximum braking intensity can be designed according to the requirements for driving comfort during deceleration and correspond to the satisfaction of a predetermined driving comfort.

[0015] The driver can transmit his comfort specification to the control device via an interface or via data transmission, such as via a personalized data record and / or store it. The degree of efficiency associated with maximizing the recuperation energy can also be adapted to his comfort specification and the maximization can be slightly lower in the case of less severe braking.

[0016] Can select or predetermine minimum braking intensity like this, thereby can meet the safety standard that at least should be observed, for the braking power that at least can provide.In addition, can select or predetermine described minimum braking intensity like this, thereby can observe the minimum safety distance with respect to the vehicle ahead.

[0017] Furthermore, the minimum and / or maximum braking intensity can be adapted to the traffic situation, the roadway topology and / or to weather conditions and in compliance with maximization of recuperation energy, driving comfort, safety requirements and safety distance requirements.

[0018] The traffic situation can be detected and observed by a sensor system, such as a front camera and / or a rear camera and / or a radar sensor and / or an ultrasonic sensor. It can be provided that the vehicle can move with the traffic and the braking curve can be adjusted in such a way that the perceived obstruction of other road users can be reduced or even prevented.

[0019] According to another scenario, after an obstacle or a traffic light is detected, the vehicle can be decelerated immediately and smoothly, i.e., with less intensity than when braking just before the obstacle or traffic light, whereby the minimum and / or maximum braking intensity can be set accordingly, for example, by a control device. Such automatic targeted braking before obstacles and / or traffic lights can be more effective, more comfortable and / or safer than when the driver personally performs targeted braking.

[0020] According to a preferred specific embodiment of the method, the data about the vehicle's surroundings and / or about the vehicle itself and / or about the electric machine are acquired by the sensor device during the braking intervention and / or are stored in a memory device and / or are at least accessible by the control device.

[0021] The storage device can be located in the vehicle or at least connected to the vehicle via a data communication platform (such as a cloud). The control device in the vehicle can advantageously calculate and implement an optimal braking trajectory within given limits. The optimal braking trajectory can vary depending on the driving situation and can be identified and taken into account accordingly.

[0022] The braking trajectory as a braking profile can advantageously correspond to an energetically optimal deceleration profile. This can advantageously be independent of the selection of an optimization algorithm and can use very different mathematical methods. The control device can be a central control device in the vehicle, which can access data for a current assessment of the efficiency of the electric traction drive. These data can be stored in the control device and / or in a storage device. The control device can also include the storage device itself.

[0023] According to a preferred embodiment of the method, the data include the charge state of the battery and / or the efficiency combination characteristic curve of the battery and / or the efficiency combination characteristic curve of the inverter and the electric machine and / or the driving resistance value of the vehicle and / or the occurring onboard electrical system load and / or the topology of the driving zone.

[0024] The efficiency combination of the battery can have an efficiency that depends on the current and / or charge state and / or temperature and / or aging state of the battery. The efficiency combination of the inverter and the motor can have an efficiency that depends on the torque and / or speed and / or temperature of the motor or the inverter.

[0025] The driving resistance of the vehicle can be based on rolling resistance and / or air resistance. These efficiency combination characteristic curves and / or driving resistance of the vehicle can be fixedly stored in a storage device or adaptively (online) acquired by sensors or by the control device itself. The control device can be connected to the corresponding sensors for this purpose. Therefore, for example, a learning function can also exist in the control device and / or an external control device or computer and be used, which learning function can acquire or estimate the driving resistance value of the vehicle by direct observation (online observation) of the slow sliding process and / or the deceleration process and / or the acceleration process and the subsequent parameter estimation.

[0026] The current gradient can be detected by means of a navigation system and / or suitable map material and / or by means of acceleration sensors and taken into account for the estimation of the recuperation energy that can be generated.

[0027] According to a preferred specific embodiment of the method, an obstacle or a traffic light switch is detected by the sensor system as the necessity for a braking intervention and the braking intensity is adjusted in such a way that it always remains below a predetermined value.

[0028] The braking intensity before an obstacle or a traffic light switch can therefore be kept below a comfort limit and / or an operating limit, wherein the operating limit ensures that the recuperation energy can be kept below certain limits because, for example, the battery in the vehicle is currently unable to absorb high power or the inverter is just about to rest or because optimal efficiency can exist for such limits with respect to the entire electric drive train.

[0029] According to a preferred specific embodiment of the method, operating limits for the inverter and / or the battery are detected or stored in a memory device and taken into account for determining the optimal braking curve.

[0030] Furthermore, the current onboard electrical system loads on the high-voltage side and / or on the low-voltage side of the drive train can be monitored and loads can be switched on by which recuperation energy can be absorbed, so that no energy has to be fed into a battery or an energy absorption device.

[0031] According to a preferred specific embodiment of the method, for target braking or for brake assistance, a friction brake and / or a hydraulic braking process for recuperation braking is actuated.

[0032] According to a preferred specific embodiment of the method, the energy expenditure for automatic activation of the brake assist by means of friction brakes and / or hydraulic braking processes is taken into account for an optimal braking curve.

[0033] According to a preferred specific embodiment of the method, a desired specification by the driver for a maximum deceleration of the vehicle is performed by the braking intervention and is taken into account and / or implemented.

[0034] The changeover from electric braking to auxiliary braking, such as target braking, by means of friction brakes, such as hydraulic brakes, can be designed in an energy-optimal manner from the perspective of recuperation. Thus, for example, the energy expenditure for automatic activation of the braking system, such as by means of the ESP hydraulic pump (electronic safety program for slip control or individual wheel braking), can be taken into account in the overall optimization of energy.

[0035] According to a preferred specific embodiment of the method, the electric machine comprises a battery, an inverter and an electric motor.

[0036] According to the present invention, a braking device for braking a vehicle having an electric motor includes a control device located in the vehicle or connected to the vehicle, the control device being connected to the electric motor and to a sensor device and being configured to maximize recuperation energy when the vehicle is braked, wherein the control device is further configured to recognize the necessity of a braking intervention while the vehicle is running; to acquire data about the vehicle's environment and / or the vehicle itself and / or the electric motor during the braking intervention; to evaluate the recuperation energy that can be generated by braking during the braking intervention based on the acquired data; to determine an optimal braking curve for the braking intensity and / or for a temporary braking effect for the braking intervention so as to maximize the recuperation energy with an optimal braking curve; and to automatically perform the braking intervention according to the optimal braking curve.

[0037] According to a preferred embodiment of the braking device, the electric machine includes a battery, an inverter and an electric motor.

[0038] The method may also be distinguished by the combination of the above-mentioned features and advantages of the braking device and vice versa.

[0039] Further features and advantages of embodiments of the invention emerge from the following description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The invention is explained in more detail below with the aid of an exemplary embodiment illustrated in the schematic drawings, in which:

[0041] Figure 1 A schematic diagram of a braking device for braking a vehicle having an electric machine according to an embodiment of the present invention is shown;

[0042] Figure 2A schematic diagram showing a control device in a braking device according to an embodiment of the present invention;

[0043] Figure 3 A block diagram shows method steps of a method for maximizing recuperation energy during braking of a vehicle having an electric machine according to an exemplary embodiment of the present invention.

[0044] In the figures, the same reference symbols denote identical elements or elements having the same function. DETAILED DESCRIPTION

[0045] Figure 1 A schematic diagram of a braking device for braking a vehicle having an electric machine according to an exemplary embodiment of the invention is shown.

[0046] exist Figure 1 , a vehicle F is shown in which a braking device 10 is present for braking the vehicle F having an electric machine EM. The braking device 10 comprises a control device SE in the vehicle, which is connected to the electric machine EM and to a sensor system S and is configured to maximize recuperation energy when the vehicle is braked, wherein the control device is configured to: recognize the need for a braking intervention during vehicle operation; acquire data about the vehicle's surroundings and / or the vehicle itself and / or the electric machine EM during the braking intervention; evaluate the recuperation energy that can be generated by braking during the braking intervention on the basis of the acquired data; determine an optimal braking profile for the braking intensity and / or for a temporary braking effect for the braking intervention in such a way that the recuperation energy is maximized with an optimal braking profile; and automatically carry out the braking intervention according to the optimal braking profile.

[0047] The electric motor EM can drive a traction drive, which can be controlled by the control device SE. The sensor system S can detect the topology of the road and / or collect visual data (or from radar) or other information about obstacles, traffic lights, weather conditions. As an alternative, the control device SE can also be arranged outside the vehicle, for example connected to a data server, to which the vehicle can also be connected (not shown).

[0048] Furthermore, friction brakes RB may be present on one or more or all wheels of vehicle F.

[0049] By means of the sensor system S, for example, the end of a traffic jam or a red traffic light can be detected.

[0050] Figure 2 A schematic diagram of a control device in a brake device according to an exemplary embodiment of the present invention is shown.

[0051] The control device SE can advantageously be connected to the inverter INV, the electric machine, for example the electric motor EMT, and the energy storage device Batt and further to a sensor system S. In this way, the function of the electric machine and / or the inverter INV and / or the energy storage device Batt, for example the charge state of the energy storage device, can be detected and monitored over a certain period of time.

[0052] The energy storage device Batt can include at least one battery. This advantageously makes it possible to estimate whether and how much energy the energy storage device can absorb now or in the near future. Based on this and on the operating data of the functions of the inverter and the electric machine, it can thus be determined how much recuperation energy can be absorbed in the system.

[0053] The control unit can therefore collect relevant information, such as the efficiency of the inverter, battery, motor, vehicle weight, etc., and obtain a Pareto-optimal deceleration profile for recovering the most energy while complying with other boundary conditions, such as safety and comfort. In this case, a precondition can be provided, according to which the driving trajectory is not carried out too slowly, so as to become a traffic obstacle, and is not carried out too suddenly, so as not to shake the passengers violently, that is, a certain degree of comfort is maintained.

[0054] The driver does not need to perform any braking intervention himself and can be informed of the automatic mode via the information system (display). If the battery cannot absorb the recuperation energy, the friction brake is automatically activated for safe braking. This can be a prerequisite for the vehicle to have sufficient environmental detection to be able to reliably perform this function.

[0055] By evaluating the recuperation energy that can be generated by braking during the braking intervention, an optimal braking profile for the braking intensity and / or for the temporary braking action can be determined for the braking intervention so that the recuperation energy is maximized with the optimal braking profile. The control device SE can then automatically and situation-adapted carry out the braking intervention according to the optimal braking profile.

[0056] Figure 3 A block diagram shows method steps of a method for maximizing recuperation energy during braking of a vehicle having an electric machine according to an exemplary embodiment of the present invention.

[0057] In a method for maximizing recuperation energy when braking a vehicle having an electric motor, the necessity for performing a braking intervention while the vehicle is in motion is identified S1; data about the vehicle's environment and / or the vehicle itself and / or the electric motor are acquired S2 during the braking intervention; the recuperation energy that can be generated by braking during the braking intervention is evaluated S3 on the basis of the acquired data; an optimal braking curve for the braking intensity and / or for a temporary braking effect is determined S4 for the braking intervention so as to maximize the recuperation energy with an optimal braking curve; and the braking intervention is automatically performed S5 according to the optimal braking curve.

[0058] Although the present invention has been fully described above with reference to preferred exemplary embodiments, the invention is not restricted thereto but can be modified in many different ways.

Claims

1. A method for maximizing recuperation energy when braking a vehicle having an electric machine (EM), the braking being triggered automatically and taking place without an action by the driver, the method comprising the following steps: - identifying (S1) the need for a braking intervention during operation of the vehicle; - acquiring (S2) data about the environment of the vehicle and / or about the vehicle itself and / or about the electric machine (EM) during the braking intervention; - evaluating the recuperation energy that can be generated by braking during the braking intervention on the basis of the acquired data (S3); - determining (S4) an optimal braking curve for the braking intensity and / or for the braking effect over time for the braking intervention in such a way that the recuperation energy is maximized with the optimal braking curve; and - automatically carrying out ( S5 ) the braking intervention according to the optimal braking curve. 2 . The method according to claim 1 , wherein a minimum and / or maximum braking intensity is determined for the optimal braking curve.

3. A method according to claim 1 or 2, wherein data about the vehicle's environment and / or about the vehicle itself and / or about the electric motor (EM) are acquired by a sensor device during the braking intervention and / or are stored in a storage device and / or can at least be called up by a control unit (SE).

4. The method according to claim 3, wherein the data includes the charge state of the battery of the electric motor (EM) and / or the efficiency combination characteristic curve of the battery and / or the efficiency combination characteristic curve of the inverter and the electric motor and / or the driving resistance value of the vehicle and / or the on-board circuit load that occurs and / or the topology of the driving zone.

5. The method according to claim 1 or 2, wherein an obstacle or a traffic light switch is detected by a sensor device as the necessity for a braking intervention and the braking intensity is adjusted in such a way that it always remains lower than a predetermined value. 6 . The method according to claim 1 , wherein operating limits for the inverter and / or the battery are detected or stored in the memory device and taken into account for determining the optimal braking curve. 7 . The method according to claim 1 , wherein for target braking or for brake assistance a friction brake and / or a hydraulic braking process for recuperation braking is actuated. 8 . The method according to claim 7 , wherein the energy expenditure for automatic activation of brake assistance by means of friction brakes and / or hydraulic braking processes is taken into account for the optimal braking curve. 9 . The method according to claim 1 , wherein a desired specification of the driver for a maximum deceleration of the vehicle is made by the braking intervention and is taken into account and / or implemented.

10. The method according to claim 1 or 2, wherein the electric machine (EM) comprises a battery, an inverter and an electric motor.

11. A braking device (10) for braking a vehicle (F) having an electric machine (EM), comprising: a control device (SE) in the vehicle (F) or connected to the vehicle (F), which is connected to the electric machine (EM) and to a sensor device (S) and is designed to maximize recuperation energy when braking the vehicle, the braking being triggered automatically and taking place without an operation by the driver, wherein the control device is further designed to: recognize the need for a braking intervention during operation of the vehicle; to acquire data about the environment of the vehicle and / or about the vehicle itself and / or about the electric machine (EM) during the braking intervention; evaluating, on the basis of the acquired data, the recuperation energy that can be generated by braking during the braking intervention; An optimal braking curve for the braking intensity and / or for the braking effect over time is determined for the braking intervention such that the recuperation energy is maximized with the optimal braking curve, and the braking intervention is automatically carried out according to the optimal braking curve.

12. The brake device (10) according to claim 11, wherein the electric machine (EM) comprises a battery, an inverter and an electric motor.

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