DE102011119378A1 - Method for controlling temperature of high-voltage power system used in motor car, involves reducing target temperature of high voltage drive system, when increased acceleration power is matched with standard acceleration phase - Google Patents

Abstract

The method involves increasing acceleration power during the starting of acceleration phase at standstill of motor car (1). The normal maximum rated output of high voltage drive system (2) is obtained due to increase of acceleration power. The target temperature of high voltage drive system is reduced, when increased acceleration power is matched with standard acceleration phase. An independent claim is included for a motor car.

Description

The invention relates to a method for tempering components of a high-voltage drive system, comprising an electric machine and a high-voltage battery, a motor vehicle in the context of an acceleration phase. In addition, the invention relates to a motor vehicle.

The performance of electrically propelled motor vehicles, unlike motor vehicles driven by internal combustion engines, is substantially determined by the overload characteristics of many electrical and / or electronic components of the high voltage propulsion system. Such a high-voltage drive system usually comprises at least one electric machine and one high-voltage battery as components, with power electronics components, for example a converter, also being present in most cases. These components are affected by the heat generated by power loss, which must not exceed certain limits.

Thus, a continuous rated power and a maximum rated power are usually specified for an electric machine. The continuous rated power is characterized in that there is an equilibrium for the generated and the dissipated power loss, that is, by a cooling device, the temperature of the electric machine can be kept substantially constant. If the electric machine is operated at a higher power, in particular the maximum rated power, the temperature of the electric machine increases depending on the thermal mass of the electric machine. If a certain limit temperature is reached, the power of the electric machine must be taken back at least to the rated continuous power, in order to avoid damage to the electric machine. For example, it is known to operate an electric machine for a predetermined period of time, for example 30 seconds, at an increased power, in particular the maximum rated power, in order then to drive for a longer period, for example 90 seconds, a lower power, so that the Electric machine can cool down again.

Comparable relationships apply to power electronics components and the high-voltage battery, in particular, the electrical and / or electronic components of a power electronics component by the design-related low thermal capacity at maximum rated power (often called peak power) show a very steep temperature rise.

For this purpose, it is otherwise known to provide a safety margin with respect to the temperature in order to prevent local overheating of the components, in particular at positions at which the temperature can not be measured.

In order to maintain the temperature of the components of the high-voltage propulsion system and other components of the motor vehicle in a suitable range for the operation of the respective component and optionally also to cool the interior of the motor vehicle according to a user's request, cooling devices (cooling systems) are provided, which are for cooling responsible for the various components. For example, it has been proposed here to use a central cooling device for the motor vehicle, which is based on a heat pump. The available cooling capacity is distributed by a central control unit, possibly also a plurality of control units, so on the various components of the high-voltage propulsion system and the motor vehicle that the greatest possible efficiency of cooling is possible. It may be provided, for example, that a component sends its current temperature and a cooling and / or heating request to a central control unit of the cooling device, which then determines on the basis of algorithms, how much cooling or heating power of the corresponding component is actually allocated ,

Also known in conventional motor vehicles so-called launch control systems. Launch control systems are activated when the motor vehicle is at a standstill and allow the shortest possible acceleration time for standard acceleration phases, for example an acceleration phase from 0 to 100 km / h. For this purpose, during a launch control process, an adjustment of operating parameters, and therefore a preconditioning, is carried out, which is intended to favor the shortest possible acceleration time. For example, operating parameters of the transmission control and / or a wheel slip control can be adjusted.

The invention is therefore based on the object to achieve a further improvement of the power available for acceleration phases in an electrically driven motor vehicle.

To solve this problem is provided according to the invention in a method of the type mentioned that automatically before the acceleration phase, especially at standstill of the motor vehicle, at least one component to a certain, compared to a usual maximum nominal power of the high voltage drive system increased acceleration performance during a standard acceleration phase permitting and / or providing the maximum rated power at least for a predefined one Proportion of the standard acceleration phase, in particular for the entire standard acceleration phase, brought assuring target temperature, in particular cooled.

In the acceleration phase, the just described increased overall acceleration performance of the high-voltage propulsion system can then be called up and thus the overall acceleration performance planned, for example from 0 to 100 km / h with regard to the standard acceleration phase, can be improved overall, in particular with regard to the shortest possible acceleration time. With particular advantage, this happens at standstill of the motor vehicle, so that ultimately an extension of the launch control functionality is proposed by the present invention, which takes into account the specific characteristics of electrically powered vehicles. So it is proposed to bring to the start of the acceleration phase, the relevant components in a thermal state of a standard acceleration phase, for example, from 0 to 100 km / h, without a reduction in performance by reaching limit temperatures, to a reduction of individual or Several components would allow and / or even allowed an increase in peak power over the maximum rated power for the entire period of the standard acceleration phase. The latter possibility can also be referred to as a so-called "over-boost".

The thermal preconditioning of the components in the context of the present invention thus, optionally combined, during the acceleration phase, in particular during the entire standard acceleration phase, can retrieve an acceleration power exceeding the maximum rated power or at least have the maximum rated power available for the entire standard acceleration phase.

In summary, therefore, a targeted temperature, in particular cooling, of components of the high-voltage propulsion system of the motor vehicle is proposed, which allows improved performance in standard acceleration phases, in particular at an acceleration from 0 to 100 km / h. Thus, especially after a launch control process, a maximum drive performance is available without energy disadvantages, comfort disadvantages or loss of life in normal operation occur.

In this case, it can be provided that the electric machine and / or the high-voltage battery and / or a power electronics component, in particular a converter, are brought to a corresponding target temperature as a component. It is particularly advantageous if all three components mentioned, so the electric machine, the high-voltage battery and the inverter, are brought to a respective, component-specific target temperature. Thus, a vote of all components on the temporarily increased total power requirement can be achieved.

With particular advantage, it can be provided that, upon cooling of at least one component to reach the target temperature associated with the component, the cooling of the component is prioritized by a cooling device compared to other cooling tasks, in particular the component to be cooled is cooled to the target temperature with maximum cooling power. As already described above, central cooling devices usually have a cooling control device (thermal management), which sets and allocates the cooling of the various components connected to the cooling device according to efficiency principles. According to the invention it is now proposed that the cooling of the critical components is prioritized by the thermal management, in particular during the launch control process, so that the cooling of the components, especially the high voltage battery, the power electronics component and the electric machine, with maximum cooling capacity. Thus, as already mentioned, the components are thermally preconditioned in order to be able to retrieve the increased power during the acceleration phase and to have sufficient buffer available via their thermal mass so that the maximum component temperature during the standard acceleration phase, for example an acceleration phase of 0 to 100 km / h, ideally not reached. However, it should be noted at this point that it may well also be possible for a component to be heated for ideal thermal preconditioning. Thus, it is known, for example, in high-voltage batteries that they have in their power output capability in a certain temperature interval substantially a plateau, so that cases may occur in which a warming to a beginning of the plateau occurs, while the usual operating temperature usually in the middle of the plateau , so in the middle of the temperature interval, is located.

In principle, it can be provided that a predetermined, defined value is selected as the target temperature for the at least one component or the component-specific target temperatures. In this case, therefore, each component is assigned a target temperature that provides a compromise for different environmental and motor vehicle conditions.

However, it is preferred if the target temperature is determined as a function of at least one further operating parameter of the motor vehicle and / or environmental parameters. In that case, the current overall situation can be adjusted to achieve an ideal acceleration performance. For this purpose, it can be provided, for example, that the target temperature is determined from a characteristic map and / or on the basis of a calculation in a thermal model of the high-voltage system and / or of the motor vehicle. It is thus conceivable, for example, to use characteristic maps from which the target temperature can be read out as a function of at least one further parameter relating to the current state of the motor vehicle and / or the environment. However, it is particularly advantageous if a thermal model is used to determine the target temperature of the individual components. Such thermal models are known for example from other technical fields, for example from rolling mills, where a permanent thermal monitoring is to take place. They map the thermal effects of processes within the motor vehicle to the current thermal state described in the thermal model. For example, it is expedient if the heating of the at least one component during the acceleration phase is predicted in the thermal model. In that case, it is thus possible to specifically determine a target temperature which fulfills the requirements, for example maintenance of a maximum rated power or an increased acceleration power over the maximum rated power for the entire standard acceleration phase.

As an operating parameter and / or environmental parameters, for example, the ambient temperature and / or an aging state of the high-voltage battery (state of health - SoH) and / or a state of charge of the high-voltage battery can be considered. While the ambient temperature mainly affects cooling by the environment of the motor vehicle, the battery-related parameters mainly relate to the ideal temperature interval in which the battery can be meaningfully operated and the power available from the battery.

It may further be provided that a cooling device based on a heat pump, in particular a common cooling device for all components of the motor vehicle to be cooled, is used as the cooling device for controlling the temperature of the at least one component. Such a cooling device usually has a central control unit (thermal management) which allocates cooling capacities or, in general, temperature control services to various components. Here, it is now conceivable, for example, prior to an acceleration phase, in particular in the context of a launch control process, to prioritize the components of the high-voltage drive system to be braked to a target temperature and to reset, for example, an interior cooling of the motor vehicle or the like.

In a further advantageous embodiment of the present invention can be provided that the Temperierungsfortschritt is displayed with respect to the target temperature display. It is thus possible for the user, in particular a driver, to be informed of the course until the target temperature or target temperatures have been reached by means of a corresponding display concept, so that the experience of the functionality described by the method according to the invention can be increased. In particular, when an acceleration power increased compared to a maximum nominal power is to be generated, an "OverBoost" display field can be realized, for example, in which the progress of the temperature control is displayed. Such an "OverBoost" display panel may, for example, supplement a general status display of the electrically powered motor vehicle, which indicates whether the motor vehicle is operating in a continuous mode (ie at nominal continuous power), in a boost mode (ie up to maximum rated power) and the like. Such a representation may, for example, be referred to as a "power meter".

Furthermore, it can be provided that, at the target temperature not reached at the beginning of the acceleration phase, the acceleration phase is carried out with a reduced power for at least one component. Thus, if the target temperature of a component can not be achieved or only after a disproportionately long time and / or if the driver starts the acceleration before reaching the target temperature for at least one component, then a restriction of the power with regard to a specific target can be provided. In particular, it may be provided that the maximum power available during the acceleration phase is reduced by the maximum rated power or the acceleration power such that the maximum power for the entire standard acceleration phase is available without exceeding a limit temperature, in other words, that the total power during the acceleration phase is chosen so that a reduced power can be maintained for the entire standard acceleration phase. For example, it is conceivable to reduce an acceleration power exceeding the maximum rated power until it can be maintained for the entire standard acceleration phase and the like. Of course it is too it is possible with other measures to take account of the reduced efficiency until the limit temperature is reached, for example by maintaining an acceleration power exceeding the maximum rated power for a shorter time during the acceleration phase.

In a particularly advantageous embodiment of the present invention, it can be provided that at least one further operating parameter of the motor vehicle is adapted to favor acceleration in the acceleration phase, in particular as part of a launch control process. It is therefore conceivable to provide a preconditioning of the components of the motor vehicle not only with regard to the temperature control of the components of the high-voltage drive system, but additionally to carry out further optimization measures, for example with regard to the transmission control and / or the wheel slip control. Launch control systems and associated launch control operations are already known in the art and need not be detailed here.

In addition to the method, the present invention also relates to a motor vehicle, comprising a cooling device for components of a high-voltage propulsion system, comprising an electric machine and a high-voltage battery, with an associated cooling control device, which is designed for carrying out a method according to one of the preceding claims. All statements relating to the method according to the invention can be analogously applied to the motor vehicle according to the invention, with which consequently the already mentioned advantages can be achieved.

Thus, in particular the cooling device, which is advantageously provided not only for the components of the high-voltage drive system, but for other, in particular all to be cooled or tempering components of the motor vehicle, include a cooling control device, which then, for example, when a stance phase, in the frame a launch control process, the method according to the invention can perform, in particular by prioritizing the cooling or temperature control of the thermally preconditioned components for the acceleration phase and the like. In this case, it is possible, for example, to deviate from a cooling concept which is usually geared to efficiency.

Further advantages and details of the present invention will become apparent from the embodiments described below and with reference to the drawings. Showing:

1 a schematic diagram of a motor vehicle according to the invention,

2 a power curve during an acceleration phase;

3 a temperature profile on a component; and

4 a possible representation for displaying the Temperierungsfortschritts.

1 shows a schematic diagram of a motor vehicle according to the invention 1 , The motor vehicle according to the invention 1 includes a high voltage drive system 2 with an electric motor 3 , a power electronics component 4 , here a converter, and a high-voltage battery 5 as components.

For cooling the components 3 . 4 and 5 of the high voltage drive system 2 and other components in the motor vehicle 1 is a cooling device 6 provided, in addition to a central cooling control unit 7 Cooling devices associated with the components 8th includes. About the control unit 7 Consequently, the thermal management in the motor vehicle takes place 1 , which is why among other things, the components 3 . 4 and 5 of the high voltage drive system 2 with temperature sensors 9 are provided. About the temperature sensors 9 For example, any component that is to be cooled generally can have its current temperature and a cooling or heating request to the cooling control unit 7 which then performs an efficiency-oriented cooling strategy to track corresponding drive parameters for the cooling devices 8th determined, so that temperature intervals in which the components to be cooled work optimally and safely, will not be left or a user-selected temperature, such as for the interior of the motor vehicle 1 , sets.

The control unit 7 is now present also for carrying out the method according to the invention, in which by suitable temperature control of the components 3 . 4 and 5 a thermal preconditioning of the high voltage drive system 2 at standstill of the motor vehicle 1 to prepare for an acceleration phase with respect to a standard acceleration phase being turned off, here as part of a general launch control process. In the present case, a standard acceleration phase from 0 to 100 km / h is considered for all calculations, which is to be accomplished in the shortest possible time, and which is differentiated from the actual following acceleration phase, which of course is unforeseeable when executed by the driver.

The standard acceleration phase is through 2 explained in more detail. There is the power against time for the duration 10 the standard acceleration phase is shown, with the dashed curve 11 represents the possibilities if no thermal preconditioning is carried out. Then, then, for a period of time, not the entire duration 10 the standard acceleration phase corresponds to a maximum rated power 12 be accelerated, up to a time 13 a limit temperature of at least one component 3 . 4 respectively. 5 is exceeded.

These processes are also out of the curve 14 in 3 See where the temperature of one of the components 3 . 4 or 5 is plotted against the time. The temperature of the component is initially during a standstill phase 15 at a default value 16 for example, an ideal operating point of the component 3 . 4 or 5 can represent in the high-voltage battery 5 for example, the middle of an ideal power output describing plateau. Will be at a time 17 now accelerated, the temperature increases according to the non-dischargeable, by the maximum nominal acceleration 12 occurring power loss, up to the time 13 a limit temperature 18 achieved by the component 3 . 4 or 5 can not be exceeded. The power available for acceleration must be lowered, at least up to the rated continuous power 19 ,

This situation should now be improved by the inventive method by the components 3 . 4 and 5 be tempered so that for the entire duration 10 the standard acceleration phase one compared to the maximum rated power 12 even increased acceleration performance 20 is available, curve 21 ,

Represents the cooling control unit 7 or another control unit therefore a stoppage of the motor vehicle 1 fixed, so a launch control process is started, in connection with other operating parameters of other systems and the high-voltage drive system 2 adapted to the upcoming acceleration phase. In addition, however, initially for each of the components 3 . 4 and 5 A target temperature determined under the current circumstances to reach through the curve 21 shown performance is suitable. For this purpose, a within the controller 7 stored thermal model 22 used, with which the temperature development of the components 3 . 4 and 5 of the high voltage drive system 2 can be calculated in advance. This is not only the case of the temperature sensors 9 taken into account recorded temperatures, but also one of a temperature sensor 23 determined ambient temperature of the motor vehicle 1 and, for example, by a battery management controller 24 transmitted, a state of charge of the high voltage battery 5 and an aging condition of the high voltage battery 5 , Of course, other operating parameters of the motor vehicle 1 and environmental parameters. Result of the calculations in the thermal model 22 are then target temperatures for the components 3 . 4 and 5 , which will generally be lower than the current temperatures, but it is also possible that heating is desired, especially in the case of the high voltage battery 5 ,

It should be noted at this point that the target temperatures can also be determined from a map or as a predetermined, fixed value in the control unit 7 can be stored.

Once the target temperatures are known, the controller controls 7 the cooling devices 8th so that the target temperatures are reached as quickly as possible. This is the cooling of the components 3 . 4 and 5 Prioritized, that is, in particular the cooling of less critical components is postponed, for example, a cabin cooling or the like.

The corresponding temperature profile is also in 3 as a curve 25 shown in more detail. At a time 26 it is recognized that the motor vehicle 1 is at a standstill, and the launch control process is started. The component becomes apparent 3 . 4 or 5 to the target temperature 27 cooled down where the bend 25 persists until the time 17 the acceleration phase begins. It becomes apparent at the curve 14 despite lower temperature rise (as the maximum rated power 19 is used, so no over-boost in the form of higher acceleration performance 20 ) the limit temperature 18 reached earlier. For the curve 25 This is only at the time 28 So at the end of the duration 10 the standard acceleration phase, given.

It should be noted at this point that it can also happen that the acceleration phase begins before the target temperature 27 has been reached or the target temperature 27 unattainable due to certain circumstances. In these cases, the requirement according to curve 21 in 2 be reduced, for example, by one between the maximum rated power 12 and the acceleration performance 20 lying power or simply the period in which the maximum rated power 12 is available, something is extended. However, it is also conceivable, if a uniform performance during the entire standard acceleration phase is desired, a continuous power below the maximum rated power 12 to choose. Various possibilities are conceivable in order to react appropriately for such cases.

Finally, it should be noted that the cooling device 6 in the present case a heat pump based cooling device 6 is that a common cooling device 6 (often referred to as a cooling system) for all components of the motor vehicle to be cooled 1 forms.

4 finally shows a way to display the Temperierungsfortschritts with respect to the target temperature on an instrument panel 29 of the motor vehicle 1 , This is a so-called bar graph display 30 used to convey the instantaneous performance of the motor vehicle to the driver. A first area 31 indicates a normal operating mode in which, for example, the continuous power can be available. The normal operating mode is active, for example, when just with increased power, such as the maximum rated power was driven, and a cooling of components 3 . 4 and or 5 is required before another area 32 , which represents a boost mode of operation is reached. In boost mode, the maximum rated power is available.

The present invention now provides for an overboost operating mode that is encompassed by an area 33 is characterized for at a standstill following acceleration phases. While the components 3 . 4 and 5 be brought to the target temperature, this approach to the target temperature to the driver on the display elements 34 the bar graph 30 brought to the display.

Claims (12)

Method for controlling the temperature of components of a high-voltage drive system ( 2 ) comprising an electric machine ( 3 ) and a high voltage battery ( 5 ), a motor vehicle ( 1 ) within the framework of an acceleration phase, characterized in that automatically already before the start of the acceleration phase, in particular when the motor vehicle is at a standstill ( 1 ), at least one component to a certain, one compared to a usual maximum nominal power ( 12 ) of the high voltage drive system ( 2 ) increased acceleration power ( 20 ) in a standard acceleration phase and / or providing the maximum rated power ( 12 ) at least for a predefined portion of the standard acceleration phase, in particular for the entire standard acceleration phase, assuring target temperature ( 27 ), in particular cooled, is. A method according to claim 1, characterized in that as component in each case the electric machine ( 3 ) and / or the high voltage battery ( 5 ) and / or a power electronics component ( 4 ), in particular a converter, to a corresponding target temperature ( 27 ) to be brought. Method according to Claim 1 or 2, characterized in that, when at least one component is cooled to reach the target temperature associated with the component ( 27 ) by a cooling device ( 6 ) the cooling of the component is prioritized compared to other cooling tasks, in particular the component to be cooled with maximum cooling power to the target temperature ( 27 ) is cooled. Method according to one of the preceding claims, characterized in that the target temperature ( 27 ) depending on at least one further operating parameter of the motor vehicle ( 1 ) and / or environmental parameters is determined. Method according to claim 4, characterized in that the target temperature ( 27 ) from a map and / or due to a calculation in a thermal model ( 22 ) of the high voltage drive system ( 2 ) and / or the motor vehicle ( 1 ) is determined. A method according to claim 4 or 5, characterized in that as operating parameters and / or environmental parameters, the ambient temperature and / or an aging state of the high-voltage battery ( 5 ) and / or a state of charge of the high-voltage battery ( 5 ). Method according to one of the preceding claims, characterized in that as a cooling device ( 6 ) for controlling the temperature of the at least one component, a heat pump based cooling device ( 6 ), in particular a common cooling device ( 6 ) for all components of the motor vehicle to be cooled ( 1 ), is used. Method according to one of the preceding claims, characterized in that a Temperierungsfortschritt with respect to the target temperature ( 27 ) is displayed. Method according to one of the preceding claims, characterized in that at not reached at the beginning of the acceleration phase target temperature ( 27 ) for at least one component, the acceleration phase is performed at a reduced power. A method according to claim 9, characterized in that the maximum available during the acceleration phase Power from the maximum rated power ( 12 ) or the acceleration power ( 20 ) is reduced so that the maximum power for the entire standard acceleration phase without exceeding a limit temperature ( 18 ) is available. Method according to one of the preceding claims, characterized in that at least one further operating parameter of the motor vehicle ( 1 ) is adjusted to promote acceleration in the acceleration phase, in particular as part of a launch control process. Motor vehicle ( 1 ), comprising a cooling device ( 6 ) for components of a high voltage drive system ( 2 ) comprising an electric machine ( 3 ) and a high voltage battery ( 5 ), with an associated cooling control device ( 7 ), which is designed for carrying out a method according to one of the preceding claims.

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