DE102015222690A1 - Controlling a drive device of a hybrid vehicle and hybrid vehicle - Google Patents

Abstract

Provided is a method for controlling a drive device (3, 203) of a hybrid vehicle (1, 201) comprising an internal combustion engine (5, 205), a first electric machine (9, 209), a second electric machine (11, 211) and an accumulator (13, 213), wherein the drive means for driving the hybrid vehicle is operable in the following three modes of operation: a pure electric operation, a serial hybrid operation and a parallel hybrid operation, the method comprising controlling the drive means in the serial hybrid mode such that the Internal combustion engine at an operating point (93) based on a combined efficiency (ηVKM × ηEM1) is operated, which depends on the efficiency (ηVKM) of the internal combustion engine and the efficiency (ηEM1) of the first electric machine.

Description

The present invention relates to a method for controlling a drive device of a hybrid vehicle and a hybrid vehicle having a drive device and a drive device controller configured to execute the control method.

A drive device of a hybrid vehicle may include various drive units for driving a drive wheel, for. As an internal combustion engine and one or more electric machines. The control of these various drive units can be performed in various ways.

From the German patent application DE 10 2013 001 095 A1 a method for operating a hybrid drive device is known, wherein the hybrid drive device has a operatively connected to a first axis of the motor vehicle internal combustion engine, also operatively connected to the first axis first electric motor and operatively connected to a second axis of the motor vehicle second electric motor. The electrical energy used to operate the second electric motor is generated by the first electric motor driven by the internal combustion engine to increase its power or is taken exclusively from an energy store for electrical energy.

The European patent EP 1 074 087 B1 discloses a control method and apparatus for the internal combustion engine of a hybrid electric vehicle, wherein an electric motor or motor / generator is disposed between the engine and the continuous variable or automatic transmission, and wherein the hybrid vehicle has a battery and associated controls. In this case, a control means keeps the power output of the internal combustion engine substantially along an ideal operating line when the speed of the engine changes. A second electric motor may also be provided and the torque output of the second electric motor may be varied by means of a system controller.

The German patent application DE 10 2012 103 292 A1 discloses a method for operating an electric drive train of a vehicle, wherein at least two electric motors, which are each in operative connection with a drive axle, and a control device are provided, wherein a driver request torque for a motor or generator operation is determined, and wherein at a present output speed required power of the electric drive train is determined, and wherein the performance of the individual electric motors are determined, and wherein the resulting power losses of the individual electric motors are minimized based on stored loss performance characteristics for the individual electric motors.

The German patent application DE 10 2009 019 485 A1 discloses a powertrain having a first electric motor and a planetary gear and vehicles having this powertrain. The drive train has a first electric machine, which is operable in a motor or regenerative operating state, and a planetary gear with a speed change device, wherein the planetary gear has a input and an output side and wherein the first electric machine in the motor or regenerative operating state controlling in the Speed change device engages, so that forms a gear ratio in the planetary gear. About the first electric machine, the transmission ratio of the planetary gear is influenced, which in addition also the operating point of the internal combustion engine is determined. The internal combustion engine is operated close to its optimum efficiency. In a purely electrical operation, the second electric machine operates as a motor and the first electric machine is idle or used as an auxiliary drive. A portion of the mechanical energy generated by the internal combustion engine is converted into electrical energy by the first electrical machine and forwarded directly to the second electrical machine. Accelerations are supported by the second electric machine. In the event of a delay, the energy store can be charged by recuperation of the braking energy.

The translation of the European patent specification DE 602 23 850 T2 discloses a method of operating a propulsion system of a hybrid vehicle, the hybrid vehicle including an internal combustion engine, a first electric motor / generator, a planetary gear mechanism, and a second electric motor / generator. A relationship between a first torque generated by the engine at the vehicle axles and a second torque generated by the second electric motor at the vehicle axles at each gear position of the gear ratio is determined by a first ratio when both the engine and the second electric motor operate normally, changed to a second ratio when either the internal combustion engine or the second electric motor is disturbed.

The German patent application DE 10 2007 054 368 A1 discloses a control architecture for selecting an optimal mode and input speed for a hybrid powertrain system that includes an internal combustion engine, first and second electric motors, and an electro-mechanical transmission that is selectively operable to transfer torque therebetween and firmer in multiple modes Translation and infinitely variable modes is operable. For each allowable operating range condition, preferred operating conditions and preferred costs are determined and based thereon a preferred operating range condition is selected. Cost structure information entered into a strategic management segment and used in an optimization segment preferably includes operating costs that are generally determined based on factors related to vehicle ride characteristics, fuel economy, emissions, and battery life for the particular torque range. In addition, costs in fuel and electrical energy consumption associated with the specific operating point of the powertrain system for the vehicle are allocated and allocated. The optimal operating costs may be determined by calculating an overall powertrain system loss that includes a term based on engine power loss driven by fuel economy and exhaust emissions plus losses in the mechanical system, losses in the electrical system, and heat losses.

In the prior art, the control of various drive units of a hybrid vehicle does not always have to lead to energy-efficient operation.

An object of the present invention is to provide a control method for a drive device of a hybrid vehicle and a hybrid vehicle, wherein various drive units of the hybrid vehicle are driven in consumption-optimal and energy-efficient and / or emission-reducing manner to produce a requested drive torque or a requested drive power.

The object is solved by the subject matters of the independent claims, which are directed to a method for controlling a drive device of a hybrid vehicle as well as to a hybrid vehicle. The dependent claims specify particular embodiments of the present invention.

According to a first aspect of the present invention, there is provided a method of controlling a drive device of a hybrid vehicle including an internal combustion engine, a first electric machine, a second electric machine, and an accumulator;
wherein for driving the hybrid vehicle, the drive means is operable in the following three modes of operation:
a purely electric operation in which a traction drive torque is effected by means of the second electric machine while the internal combustion engine is turned off;
a serial hybrid operation in which the traction drive torque is effected by the second electric machine and the internal combustion engine drives the first electric machine to generate electric power;
a parallel hybrid operation in which a traction drive torque is effected by means of the internal combustion engine.
The method has:
Controlling the drive means in the series hybrid operation such that the internal combustion engine is operated at an operating point based on a combined efficiency, which depends on the efficiency of the internal combustion engine and the efficiency of the first electric machine.

The consideration of the combined efficiency of the first electric machine and the internal combustion engine in the serial operation results in a CO ₂ -optimized serial hybrid operation as discussed below. In the further course, the delimitation of the three modes of operation is also explained by explaining the various thresholds of operation. In addition to the optimization of serial operation, the described delimitation can then also lead holistically to a consumption-optimal "overall operation" of the hybrid vehicle.

Basically, beyond the above-mentioned three modes of operation, further modes of operation are conceivable, e.g. B. concern the recuperation of braking energy in deceleration phases. The three operating modes listed here are, in particular, the essential operating modes that relate to the generation of propulsion or drive power.

The method may, for. B. be implemented in software and / or hardware and can be loaded in particular in an engine control unit and executed by the engine control unit. The internal combustion engine can, for. B. include a diesel engine or a gasoline engine. The internal combustion engine may further include a fuel tank with fuel. The fuel can be supplied to combustion chambers of the internal combustion engine, in particular via injection pumps and a valve. Depending on an amount of fuel supplied per unit time, an output of the internal combustion engine can be controlled.

The first electric machine can be operated in an electromotive or a regenerative mode. The second electric machine can also be operated in an electromotive operation or a regenerative operation.

For example, the internal combustion engine, the first electric machine, and the second electric machine may be similarly sized in terms of their maximum output, for example differing by less than 30% in their maximum output. The maximum output torques of the various drive units may differ, for example, depending on the transmission and / or translation design, for example, the second electric machine can provide the highest maximum output torque, the combustion engine can provide, for example, a mean maximum output torque and the first electric machine, for example, a minimum maximum output torque can provide. Thus, in particular the second electric machine can advantageously be used as a traction machine, that is to say operated in electromotive operation.

The drive device may further include a main clutch between the internal combustion engine and a drive wheel. Optionally, a transmission can be arranged between the main clutch and the internal combustion engine. In other embodiments, a transmission is missing and there may be a fixed gear ratio (eg, i = 2.8) between an output shaft of the internal combustion engine and the drive wheel. A specific driving speed can thus correspond in these embodiments to a specific rotational speed of the internal combustion engine.

Optionally, a first clutch between the first electric machine and an output shaft of the internal combustion engine may be provided in order to be able to decouple the first electric machine in certain operating conditions or operating modes, as an option.

Furthermore, optionally between the second electric machine and the drive wheel, a second clutch may be provided in order to decouple the second electric machine in certain operating conditions or in certain operating modes of the drive wheel and to decouple from the output shaft of the internal combustion engine can.

In the purely electrical mode, the main clutch may be open and the second clutch (if any) may be closed (that is, in the coupled state).

In the serial hybrid mode, the main clutch may be open and the first clutch (if any) may be closed, and also the second clutch (if any) may be closed. The serial hybrid operation can be performed with or without load point boost. That is, the internal combustion engine may be controlled such that its output power is higher than a target drive power, so that the accumulator can be further charged with the excess power.

In the parallel hybrid mode, the main clutch is closed and the first clutch (if present) and the second clutch (if present) are open unless load point boosting is performed. In a parallel hybrid mode with load point boost across the first electric machine, the main clutch may be closed, the first clutch may be closed, and the second clutch (if any) may be open. Alternatively, in the parallel hybrid mode, a load point boost may also be made via the second electric machine, in which case the main clutch is closed, the first clutch (if any) is open, and the second clutch (if any) is closed.

The efficiency of the internal combustion engine can, for. B. determined using (eg, experimentally determined) specific fuel consumption (eg, consumed fuel mass divided by generated energy, eg, measured in units g / kWh). The efficiency of the internal combustion engine can be higher, the lower the specific fuel consumption. The specific one Fuel consumption can be z. B. depending on a speed and torque or power of the internal combustion engine and / or depend on it. Lines of the same specific fuel consumption (so-called iso-lines) can, for. B. in a coordinate system, which plots the speed of the internal combustion engine against the torque and / or the power of the internal combustion engine, are shown. In the same coordinate system z. B. also be entered iso-curves for different output powers.

During the serial operation, the internal combustion engine drives the first electric machine, which generates electric power in regenerative operation, and the thus generated electric power is supplied to the second electric machine to drive the drive wheel. The consideration of the efficiency of the first electric machine accounts for losses in the conversion of the mechanical energy provided by the internal combustion engine into electrical energy, which takes place by means of the first electric machine. The operating point of the internal combustion engine obtained based on the combined efficiency of the first electric machine and the internal combustion engine may differ from the operating point, which would be determined purely based on the efficiency of the internal combustion engine. In particular, the operating point obtained based on the combined efficiency may be shifted to higher speeds and / or lower torques of the internal combustion engine for a given target drive power and / or given target drive torque. Thus, the hybrid vehicle or its drive device can be operated more energy-efficient and in particular CO ₂ -optimized in serial hybrid mode.

The operating point may be an extreme point of the combined efficiency for a given desired power and / or a given desired torque. The extreme position can specify the argument or arguments (eg speed and torque) for which the combined efficiency assumes an extremum (eg minimum or maximum). If the efficiency z. B. based on the specific fuel consumption, the location of the arguments or argument (eg speed and torque) can be determined, in which the combined efficiency takes a maximum. Thus, in some embodiments, a simple rule for determining the operating point is given. The efficiencies of the internal combustion engine and the first electric machine may have previously been determined experimentally and / or by simulation, and they may in particular have been determined over all possible operating ranges.

Controlling the drive means in the serial hybrid mode may further include retrieving the operating point from a predetermined operating point curve, wherein the operating point curve defines the operating points for a plurality of desired powers and / or target torques. The operating points are given by a plurality of extreme points of the combined efficiency for the plurality of desired powers and / or set torques. The operating point curve can z. B. can be determined on a test bench and can be stored in an engine control unit of the hybrid vehicle. Thus, the process can be further simplified.

The combined efficiency may be the product of the efficiency of the internal combustion engine and the efficiency of the first electric machine. The target power may correspond to a target drive power or may be a sum of a target drive power and a target load point boost power. Thus, the serial operation can be carried out with or without load point increase energy-efficient and CO ₂ -optimized.

The purely electrical operation may be performed if the vehicle speed (or rotational speed of the drive wheel) is below a vehicle speed threshold (or rotational speed threshold) and / or a target drive power and / or target drive torque is below an electrical operating threshold.

The driving speed threshold can be determined depending on a gear ratio between the internal combustion engine and the drive wheel and it can be determined depending on a deployable ratio of an optional existing transmission. Below the vehicle speed threshold, in particular with a fixed transmission ratio between an output shaft of the internal combustion engine and the drive wheel, the speed of the internal combustion engine may be too low to be able to provide a drive torque.

The electrical operation threshold can be z. For example, it may be an electrical operation power threshold or an electrical operation torque threshold. The electrical operation threshold can be z. B. depending on Determined efficiency of the internal combustion engine, wherein energy-inefficient low-load operating points of the internal combustion engine are substituted by a purely electrical operation. The electrical operation threshold can be z. B. also be determined depending on a capacity of the accumulator, wherein the electrical operating threshold for increasing capacity of the accumulator may increase. Other dependencies are possible. In order for a reliable operation can be ensured, in particular, the internal combustion engine is not operated in low-load operating points with energy-inefficient efficiencies, the battery is not loaded too much and the internal combustion engine is not used to drive the drive wheel at low speeds.

The serial hybrid operation may be performed if both the vehicle speed is below the vehicle speed threshold and a desired drive power and / or a desired drive torque are above the electrical operating threshold. Since the main clutch is opened in serial operation, the speed and / or the torque of the internal combustion engine can be adjusted independently of the driving speed so that the internal combustion engine operates at a permitted, in particular optimum, operating point to drive the first electric machine for generating electrical energy which in turn is used by the second electric machine to apply the target drive power or a target drive torque to the drive wheel in the electromotive operation.

The serial operation may be further performed if a target drive power and / or a target drive torque is above a vehicle speed dependent parallel hybrid drive threshold. The parallel hybrid operation threshold can be z. A parallel hybrid mode torque threshold or a parallel hybrid mode power threshold. The parallel hybrid operation threshold can be z. B. represent a power or a torque which is maximum of the internal combustion engine (optionally including "boost" support of the first electric machine and / or the second electric machine) can be generated. In particular, with a fixed gear ratio between an output shaft of the internal combustion engine and the drive wheel, the parallel hybrid operation threshold may be dependent on the vehicle speed. The parallel hybrid operation threshold can be z. B. increase linearly with the driving speed. Other dependencies are possible. Thus, the drive device can be reliably operated, and the target drive power and / or the target drive torque can be reliably generated on the drive wheel.

The parallel hybrid operation may be performed if both the vehicle speed is above the vehicle speed threshold, target engine power and / or target torque is below the vehicle speed dependent parallel hybrid operating threshold, and target power and / or torque are above the electrical operating threshold. This allows clear transitions between the different operating modes to be defined. In particular, the parallel hybrid operation may preferably be performed whenever the above-mentioned conditions are satisfied. Consumption studies have found that in virtually all cases where parallel hybrid operation is possible due to the constraints imposed by the internal combustion engine, parallel hybrid operation is more fuel-efficient and CO ₂ -optimal than hybrid serial operation over hybrid serial operation.

The electrical operation threshold can be z. B. for driving speeds below the vehicle speed threshold have a constant value, which may be greater than another value of the electric operation threshold for driving speeds above the vehicle speed threshold. Other embodiments are possible.

The parallel hybrid operation threshold can be given as the sum of the drive powers and / or drive torques which can be generated at most by the internal combustion engine and taking into account an optionally possible "boost" support from the first electric machine and / or from the second electric machine. In other embodiments, the parallel hybrid threshold may be given as the maximum torque that can be generated by the internal combustion engine. In other embodiments, the parallel hybrid operation threshold may be given as the sum of the drive powers and / or drive torques that are maximally producible by the internal combustion engine and taking into account an optionally possible "boost" assistance from the first electric machine.

In parallel hybrid operation, in addition to the maximum power and / or the maximum torque of the internal combustion engine, at least partially the first electric machine and / or the second electric machine may additionally contribute to the traction drive torque and / or traction drive power. This modification is also called "boost". Thus, the parallel operation can be easily extended to higher drive power and / or drive torques.

According to a second aspect of the present invention, there is provided a hybrid vehicle including a drive device including an internal combustion engine, a first electric machine, a second electric machine, and an accumulator;
wherein for driving the hybrid vehicle, the drive means is operable in the following three modes of operation:
a purely electric operation in which a traction drive torque is effected by means of the second electric machine while the internal combustion engine is turned off;
a serial hybrid operation in which the traction drive torque is effected by the second electric machine and the internal combustion engine drives the first electric machine to generate electric power;
a parallel hybrid operation in which a traction drive torque is effected by means of the internal combustion engine,
In this case, the hybrid vehicle further comprises a drive device control, which is designed to carry out a method according to one of the preceding embodiments.

Embodiments of the present invention will now be explained with reference to the accompanying drawings. The invention is not limited to the illustrated or described embodiments.

1 schematically illustrates a hybrid vehicle according to an embodiment of the present invention, which is configured to carry out a method according to an embodiment of the present invention;

2 schematically illustrates a hybrid vehicle according to another embodiment of the present invention, which is configured to carry out a method according to an embodiment of the present invention;

3 Illustrates curves of the in 1 or 2 illustrated hybrid vehicles in parallel hybrid operation provided torque and power;

4 schematically illustrates a method for controlling a drive device of a hybrid vehicle according to an embodiment of the present invention;

5 illustrates various operating modes of the in 1 and 2 illustrated hybrid vehicles used in a method according to an embodiment of the present invention;

6 illustrates fuel consumption in various modes of operation as determined by the in 1 and 2 illustrated vehicles are running, and

7 FIG. 10 illustrates curves representing efficiencies considered in embodiments of the present invention. FIG.

This in 1 schematically illustrated hybrid vehicle 1 has a drive device 3 as well as a drive device control 6 , which is designed, a method for controlling the drive device 3 of the hybrid vehicle 1 according to an embodiment of the present invention. The drive device 3 includes an internal combustion engine 5 with several cylinders 7 , a first electric machine (also called a generator) 9 , a second electric machine (also called a traction machine) 11 and an accumulator 13 , which has not illustrated power supply cables (and power electronics) with both the first electric machine 9 as well as the second electric machine 11 connected is.

The drive device 3 is to drive the hybrid vehicle 1 operable in three operating modes. First, in a purely electrical operation, in which a traction drive torque (which, for example, at the drive wheels 15 abuts) by means of the second electric machine 11 is effected while the internal combustion engine 5 is switched off (ie, in particular no fuel from an unillustrated tank is supplied). Second, the drive device 3 in a serial hybrid mode operable in which the traction drive torque by means of the second electric machine 11 is effected and the internal combustion engine 5 the first electric machine 9 for generating electrical energy, which in turn drives the second electric machine 11 is supplied (either directly or through the accumulator 13 ). The drive device 3 third is operable in a parallel hybrid operation, in which a traction drive torque by means of the internal combustion engine 5 is effected and in particular the second electric machine 11 and / or the first electric machine 9 are switched off.

In the in 1 illustrated hybrid vehicle 1 includes the drive device 3 Furthermore, a main clutch K0 ( 17 ) and a transmission 19 , both between the internal combustion engine 5 and a wheel drive train 21 are arranged. The wheel drive train 21 is about a differential 25 with associated differential ratio 23 with the drive wheels 15 mechanically connected. The first electric machine 9 is via a first clutch K1 ( 27 ) and a first translation element 29 with an output shaft 31 the internal combustion engine 5 connected, the output shaft 31 mechanically with an input shaft 32 of the transmission 19 connected is. An output shaft 33 of the transmission 19 is with the main clutch K0 ( 17 ) connected. The second electric machine 11 is about a second translation element 35 and a second clutch K2 ( 37 ) with the wheel drive train 21 connected.

In the hybrid vehicle 1 a serial-parallel hybrid concept will be implemented. About a scaling of the accumulator 13 (also referred to as HV battery) with respect to the energy content and / or performance (discharge and charging power), the hybrid vehicle 1 be designed as HEV (Hybrid Electric Vehicle) as well as a plug-in HEV (PHEV). The first electric machine 9 (also referred to as EM1) is z. B. with respect to the power and the torque dimensioned such that taking into account the transmission ratio 29 from the internal combustion engine 5 to the first electric machine 9 every possible internal combustion engine operating point (also referred to as operating point) can be set in serial mode. The second electric machine 11 (Also referred to as electric traction motor EM2) is, for example, with respect to the power dimensioning of the power dimensioning of the internal combustion engine 5 ajar, that is, it can provide similar maximum performance.

For a parallel hybrid operation can translations of the internal combustion engine to the drive wheel 15 be provided in various ways or characteristics (eg, stepped or continuously), in which case at least one over-drive translation with z. B. a typical translation of the internal combustion engine 5 to the drive wheel 15 from Z. B. i = 2.8 is provided, which means that when the output shaft 31 the internal combustion engine 5 2.8 times turns the drive wheel 15 once turns.

The ratios of the traction motor EM2 and the generator EM1 can be implemented in the embodiment, for example, both as a spur gear as well as a (braked) planetary gear. Via the main clutch K0, the parallel power path (shaft 33 ) from the drive wheel 15 be decoupled. Traction motor EM2 and generator EM1 are (optionally) each via the second clutch 37 (also referred to as K2) and the first clutch 27 (also referred to as K1) decoupled to reduce drag losses. All couplings K0, K1 and K2 can be designed, for example, as frictional Lammelenkupplungen and / or positive jaw clutches. The generator EM1 can operate essentially or exclusively as a generator, it can be used to start the internal combustion engine, or it can be used in parallel hybrid mode for boosting the internal combustion engine 5 be used. The purely electric operation (EV operation) and the recuperation can be performed via the traction motor EM2 (that is, the second electric machine) while the main clutch K0 is opened and the second clutch K2 is closed.

Table 1 below lists the various operating modes in which the drive device 3 is operable, together with the respective coupling states of the main clutch K0, the first clutch K1 and the second clutch K2. Table 1: operation mode K0 K1 K2 EV operation open any closed recuperation open any closed Hybrid serial operation with and without load point boost open closed closed Parallel hybrid operation without load point boost closed open open Parallel hybrid operation with load point boost via EM1 closed closed open Parallel hybrid operation with load point boost via EM2 closed open closed

Thus, the drive device 3 in a purely electrical operation (EV operation), a serial hybrid operation and a parallel hybrid operation operable. Both the serial hybrid operation and the parallel hybrid operation can be carried out in each case without or with load point increase, as can be seen from the above Table 1.

About the direct connection of the second electric machine 11 (EM2) to the drive wheel 15 An efficient electric drive and efficient recuperation are feasible.

During serial hybrid operation, even at very low vehicle speeds and / or wheel speeds, the maximum internal combustion engine power can be used to drive the vehicle, since in this case the main clutch K0 is open and therefore the engine speed 5 can be set optimally regardless of the driving speed. From purely electrical operation (EV operation), with the main clutch open, K0 can be reached via the first electric machine 9 (Generator EM1) a very comfortable and neutral traction internal combustion engine Zustart be achieved.

If an additional load point increase in parallel operation is required, the generator operation required therefor for generating electrical power for charging the accumulator can be optionally via the second electric machine 11 (Drive motor EM2) or the first electric machine 9 (Generator EM1). In parallel hybrid operation without the need for additional load point boosting, in 1 illustrated hybrid vehicle 1 to minimize the drag losses the second electric machine 11 (Drive motor EM2) and the first electric machine 9 (Generator EM1) by opening the second clutch 37 (K2) and opening the first clutch 27 (K1) are decoupled.

The selection of all-electric, hybrid, hybrid, and parallel hybrid modes may take into account the respective efficiencies of powertrain components for the purposes of fuel economy.

2 illustrates a hybrid vehicle 201 according to a further embodiment of the present invention, wherein in structure and / or function similar or identical components in 1 and 2 are denoted by reference numerals, which are the same in the last two places. For simplicity, in the following description, the reference numerals will be partly from both 1 and 2 indicated, each separated by a comma.

This in 2 illustrated hybrid vehicle 201 can be understood as a "simplified" system topology without a decoupling of drive motor EM2 and generator EM1 and without a transmission (stepped or stepless), so that only an overdrive ratio of the internal combustion engine 205 to the drive wheel 215 can be present.

In electrical operation, the main clutch K0 is open. Internal combustion engine and electric generator EM1 stand still (speed = zero). The driving request is provided via the electric driving motor EM2 with corresponding removal of an electric power from the HV battery. The hybrid driving mode can be displayed serially and in parallel. In serial hybrid mode, the main clutch K0 is open. The speed of the internal combustion engine is freely adjustable. The mechanical power of the internal combustion engine is converted into an electrical power via the generator EM1. This electrical power is used in accordance with demand for recharging the HV battery and used by the drive motor EM2 to represent the driving request.

In parallel hybrid mode, the main clutch K0 is closed. The speed of the internal combustion engine is coupled via the overdrive ratio to the wheel speed. The mechanical power of the internal combustion engine is used in accordance with demand via a generator operation of the electric generator EM1 for recharging the HV battery and transmitted mechanically to represent the driving request directly to the wheel. In parallel hybrid operation without the need for an additional increase in load point, generator EM1 can be decoupled to minimize drag losses (with dynamic losses acceptable to drivers, for example, GRA and / or ACC operation). In yet another embodiment, the first clutch may also be used 227 absence.

3 illustrated for parallel hybrid operation in a coordinate system with an abscissa 43 , which is the speed of the internal combustion engine 5 . 205 illustrated, and with an ordinate 45 indicative of the power and / or torque applied to the input shaft 32 of the transmission 19 or one output shaft 233 is an achievement 47 the internal combustion engine 5 . 205 , a system performance 49 , a torque 51 the internal combustion engine 5 . 205 as well as a system torque 53 the respective entire drive device 3 . 203 , The system performance 49 and the system torque 53 are defined in consideration of an electric boost assist by the generator EM1 (and / or the traction motor EM2). Performance and torque requirements (that is, nominal powers or setpoint torques) above the internal combustion engine full load can thus be achieved in parallel hybrid operation up to the defined system performance 49 and up to the defined system torque 53 via a combined combustion and electromotive operation with corresponding electrical power consumption from the accumulator (HV battery) 13 . 213 being represented.

In the 1 and 2 illustrated drive device controls 6 . 206 are trained, a procedure 38 for controlling the drive device 3 . 203 of the hybrid vehicle 1 . 201 According to one embodiment of the present invention, which schematically in 4 is illustrated.

First, in one step 39 of the procedure 38 the drive device 3 . 203 provided the first electric machine 9 . 209 , the second electric machine 11 . 211 , the internal combustion engine 5 . 205 and an accumulator 13 . 213 includes. In this case, the drive device 3 . 203 to drive the hybrid vehicle 1 . 201 Operable in the following three operating modes:
a purely electric operation in which a traction drive torque is effected by means of the second electric machine while the internal combustion engine is turned off;
a serial hybrid operation in which the traction drive torque is effected by the second electric machine and the internal combustion engine drives the first electric machine to generate electric power; and
a parallel hybrid operation in which a traction drive torque is effected by means of the internal combustion engine.

In a further process step 41 becomes the drive device 3 . 203 controlled in serial hybrid mode such that the internal combustion engine 5 . 205 operated at an operating point based on a combined efficiency that depends on the efficiency of the internal combustion engine 5 . 205 and the efficiency of the first electric machine 9 . 209 depends.

Based on the definition of in 3 shown system performance and system torque, the various operating modes (ie pure electric operation, serial hybrid operation and parallel hybrid operation) for driving the hybrid vehicle 1 . 201 is visualized in a graph of available drive power (and / or desired drive power) versus vehicle speed (or drive wheel speed), as in FIG 5 is shown. On the abscissa 55 in 5 the speed of the hybrid vehicle is plotted and on the ordinate 57 the (available) drive power is plotted. In one area 59 and an area 60 is the purely electrical operation (EV operation) performed, in one area 61 The serial hybrid operation (serial operation) is performed and in one area 63 the parallel hybrid operation (parallel operation) is performed. The curve 64 represents the driving resistance during constant speed travel in the plane. This in 5 The diagram shown can be represented analogously as available drive torque (instead of drive power) over the vehicle speed or the wheel speed.

The purely electrical operation is in range 59 performed if the vehicle speed is below a vehicle speed threshold 65 and the drive power (target drive power) is below an electrical operation power threshold 67 lies.

Furthermore, the purely electrical operation in area 60 performed if the vehicle speed is above the vehicle speed threshold 65 is and the drive power (target drive power) below another electrical operating power threshold 68 which is smaller (eg, 3 kW) than the electric-operation-power threshold 67 ,

The parallel hybrid operation in the area 63 is performed if both the vehicle speed is above the vehicle speed threshold 65 is a target drive power below the vehicle speed dependent parallel hybrid operation power threshold 69 is, as well as a target drive power above the other electrical operation threshold 68 lies. The parallel hybrid operation performance threshold 69 is here as the sum of the maximum output power 71 the internal combustion engine 5 . 205 and the boost support of the first electric machine 9 . 209 and / or the boost support of the second electric machine 11 . 211 Are defined. In that area 73 Thus, in parallel hybrid operation, a boost takes place by means of the first electric machine EM1 and / or the second electric machine EM2.

The serial hybrid operation is in the range 61 performed if both the vehicle speed below the vehicle speed threshold 65 is as well as the target drive power above the electrical operation power threshold 67 lies. Further, the serial hybrid operation becomes in the range 61 performed if both the vehicle speed above the vehicle speed threshold 65 is as well as the target drive power above a vehicle speed dependent parallel hybrid operation performance threshold 69 lies.

The electrical operation is with respect to the maximum drive power representation for consumption minimization by the electrical operation threshold 67 and by the further electrical operation threshold 68 limited (here, for example: up to about 49 km / h, about 15 kW drive power from about 49 km / h about 3 kW drive power).

The parallel hybrid operation is performed as soon as taking into consideration the transmission ratio of the internal combustion engine 5 . 205 to the drive wheel 15 . 215 a minimum speed of the internal combustion engine 5 . 205 is exceeded. In an exemplary embodiment, the overdrive ratio is the internal combustion engine 5 . 205 to the drive wheel 15 . 215 i = 2.8, resulting in a speed of the internal combustion engine at about 49 km / h vehicle speed 5 . 205 of about 1200 rpm. From this speed, the internal combustion engine is able to automatically generate the drive torque or the drive power. The parallel hybrid operation is limited in terms of the maximum drive power representation by the maximum load of the internal combustion engine and taking into account the electrical boost support by the generator EM1 and / or the traction motor EM2 by the system performance (here by the parallel hybrid operation power threshold 71 (without boost) or 69 (with boost)). Above the electrical operation power threshold 67 and above the parallel hybrid mode power threshold 69 the serial hybrid operation is performed. The serial hybrid operation is related to the maximum drive power representation by the sizing of the second electric machine 11 . 211 (Drive motor EM2) through the line 75 limited. The thresholds 67 . 68 . 69 . 71 . 65 can be determined to be optimal in terms of consumption or CO ₂ optimal.

The derivation of a CO ₂ -optimized hybrid operating strategy is based on a comparison of the conventional, purely internal combustion engine drive with an intermittent electric-internal combustion engine driving. In hybrid operation (serial and / or parallel), besides the recuperation, the additional fuel consumption due to load point increase as well as the energy input for the electric driving and the engine starting processes must be considered. The electric driving is then permitted only for an energetically meaningful range, for which the overall efficiency, despite the multiple, lossy energy conversion is greater than in pure combustion engine operation.

The transition from electric driving to hybrid driving takes place when the driver input drive power derived from the pedal value exceeds a predetermined value. This additionally also dependent on the wheel speed or the vehicle speed power threshold is determined using a mathematical optimization method, taking into account all powertrain component efficiencies for different driving cycles consumption optimal.

For the in 2 shown exemplary embodiment and taking into account typical component efficiencies up to about 49 km / h, a marginal propulsion power of about 15 kW for electrical operation and from 50 km / h, a marginal propulsion power of about 3 kW for electrical operation result without the present invention is limited to these values and limits.

In parallel hybrid operating states, an equivalent serial hybrid operating state can generally also be represented. For typical embodiments, however, for most diverse driving requirements, considering that all powertrain component efficiencies are considered, the serial operation tends to have lower efficiency over parallel hybrid operation, as in FIG 6 is illustrated. Therefore, if possible, parallel hybrid operation should be preferred in hybrid operation because of its higher efficiency over serial hybrid operation.

6 illustrates the fuel consumption in mass per unit of time as a function of speed and load point increase. Almost for all types of speed and load point boost, which in 6 As shown, the parallel hybrid operation requires less fuel consumption per unit time than the serial hybrid operation. The parallel hybrid operation is characterized by surface elements 77 designated and the serial hybrid operation is by surface elements 79 illustrated. Only for relatively low speeds and relatively high load point increases does the parallel hybrid operation show higher fuel consumption per unit time than serial hybrid operation.

In serial hybrid operating states, the speed of the internal combustion engine is freely adjustable because of the open main clutch K0. (The rotational speed of the electric generator EM1 is mechanically coupled to the rotational speed of the internal combustion engine.) The rotational speed and torque of the electric traction motor EM2 are mechanically coupled to the wheel speed and to the driver requested wheel torque.) The mechanical power of the internal combustion engine is supplied via the generator EM1 converted into an electrical power. This electrical power is used as the need arises for reloading the HV battery (load point raising, P _LPA) and used by the travel motor EM2 for driving the vehicle (P _{EM2, electrical).}

The CO ₂ -optimized serial hybrid operation takes into account the optimum combined efficiency of internal combustion engine and electric generator EM1. In this CO ₂ -optimized serial hybrid operation, the operating points of the internal combustion engine are typically shifted to higher speeds compared to their optimum efficiency, since the electric generator EM1 typically achieves its efficiency optimum at higher speeds than the internal combustion engine. Basically, for example, the following relationship for determining the consumption-optimal speed of the internal combustion engine in serial hybrid operation as a function of the required Nachladeleistung in the HV battery, depending on the required electric power to the traction motor EM2 to represent the driving requirement and in dependence of the efficiencies of internal combustion engine and electric Generator EM1 apply: n _{VKM, CO2 opt.} (P _LPA + P _{EM2, electrical} , η _VKM , η _EM1 ) = max ((η _VKM × η _EM1 ) (P _LPA + P _{EM2, electric} ))

n_VKM,CO2-opt

die CO₂-optimierte Drehzahl der Verbrennungskraftmaschine,

η_VKM

den Wirkungsgrad der Verbrennungskraftmaschine,

η_EM1

den Wirkungsgrad der ersten Elektromaschine,

P_LPA

die Lastpunkterhöhungsleistung, und

P_{EM2,elektrisch}

die der zweiten Elektromaschine zugeführte elektrische Leistung.

This designates

n _{VKM, CO2 opt}

the CO ₂ -optimized speed of the internal combustion engine,

η _VKM

the efficiency of the internal combustion engine,

η _EM1

the efficiency of the first electric machine,

P _LPA

the load point elevation performance, and

P _{EM2, electric}

the electric power supplied to the second electric machine.

The efficiencies are taken at the location (P _LPA + P _{EM2, electrical} ).

7 illustrated in a coordinate system with abscissa 81 indicating the speed of the internal combustion engine 5 . 205 indicates, and with ordinate 83 indicating the torque provided by the internal combustion engine 5 . 205 indicating lines 85 same specific fuel consumption, as well as dashed lines 87 for various total output services, that is the services provided by the internal combustion engine 5 . 205 be generated. The line 89 illustrates the consumption-optimal efficiency of the internal combustion engine 5 . 205 alone and the line 91 illustrates an operating point curve obtained by consumption optimization of a combined efficiency, the combined efficiency of the efficiency of the internal combustion engine 5 . 205 as well as the efficiency of the first electric machine 9 . 209 depends. In particular, the combined efficiency is determined by a product of these two efficiencies, as set forth above in the equation.

To the working point of the internal combustion engine 5 . 205 in serial hybrid mode at a (given) setpoint power is the intersection of the working point curve 91 with that line 87 found, which corresponds to the desired target performance. If z. B. a target power is 20 kW (which, for example, the sum of a target drive power of 15 kW at the drive wheel 15 and may correspond to a load point increase of 5 kW for charging the accumulator), this results in the intersection of the corresponding curve 87 with the working point curve 91 the operating point 93 which defines a speed of about 2200 rpm and a torque of about 77 Nm. By means of a suitable fuel supply is then the operating point 93 corresponding torque and the working point 93 corresponding speed in the internal combustion engine 5 . 205 set. This is given by the drive device control 6 . 206 control signals 8th . 208 to the internal combustion engine 5 . 205 out. Further control signals 10 . 210 become the first electric machine 9 . 209 and other control signals 12 . 212 be to the second electric machine 11 . 211 to control the same issued. The drive device control 6 . 206 can also control signals 14 . 214 for controlling the main clutch K0 ( 17 ), the first clutch K1 ( 27 ) and the second clutch K2 ( 37 ) and control signal 4 to the gearbox 19 output. Changes from the operating point 93 a requested target power up or down, the operating point along the operating point line 91 shifted, as indicated by arrows.

The operating point adjustment of the internal combustion engine in serial hybrid mode with changing driving requirements is preferably along the line 91 to perform the optimum combined VKM-EM1 efficiency. The operating point adjustment of the internal combustion engine in serial operation should preferably only along the line 91 optimum combined VKM-EM1 efficiency.

• • Ein EV-Betrieb kann vorzugsweise bis ca. 50 km/h und einer maximalen Antriebsleistung von ca. 15 kW erfolgen.
• • Im Hybridbetrieb kann – sofern möglich – der parallele Betrieb aufgrund seiner höheren Effizienz gegenüber dem seriellen Hybridbetrieb bevorzugt werden (hier paralleler Hybridbbetrieb ab ca. 49 km möglich mit VKM-Drehzahl >≈ 1200 U/min bei v_1000,i=2,8 = 41,4 km/h).
• • Im parallelen Hybridbetrieb kann der Übergang in den seriellen Hybridbetrieb bei Drehmomentanforderungen größer VKM-Volllast oder alternativ größer Systemvolllast erfolgen.
• • Die VKM-Betriebspunktverstellung im seriellen Hybridbetrieb kann vorzugsweise entlang der Linie des optimalen kombinierten VKM-EM1-Wirkungsgrads erfolgen.

From the presented method for the development of a CO ₂ -optimal operating strategy may be in some embodiments, for. B. the following basic guidelines:

• • An EV operation can preferably take place up to approx. 50 km / h and a maximum drive power of approx. 15 kW.
• • In hybrid mode, if possible, parallel operation can be preferred because of its higher efficiency compared to serial hybrid operation (here parallel hybrid operation possible from approx. 49 km with VKM speed> ≈ 1200 rpm at v _{1000, i = 2.8} = 41.4 km / h).
• • In parallel hybrid mode, the transition to serial hybrid operation may occur with torque requests greater than VKM full load or alternatively greater system full load.
• The VKM operating point adjustment in serial hybrid mode may preferably be along the line of optimum combined VKM-EM1 efficiency.

LIST OF REFERENCE NUMBERS

1

hybrid vehicle

3

driving means

5

Internal combustion engine

6

Drive device control

7

cylinder

8th

control signal

9

first electric machine

10

control signal

11

second electric machine

12

control signal

13

accumulator

14

control signal

15

drive wheel

17

Main clutch K0

19

transmission

21

Radantriebstrang

23

differential translation

25

differential

27

first clutch K1

29

translation element

31

Output shaft internal combustion engine

32

Input shaft gear

33

Output shaft gear

35

translation element

37

second clutch K2

38

method

39

step

41

step

43

abscissa

45

ordinate

47

Engine power

49

system performance

51

Engine torque

53

system torque

55

abscissa

57

ordinate

59, 60

Areas of pure electrical operation

61

Range of hybrid serial operation

63

Area parallel hybrid operation

64

Travel resistance at constant speed travel

65

Speed Threshold

67

Electrical operating threshold

68

additional electrical operation threshold

69

Parallel hybrid mode threshold

71

maximum output of the internal combustion engine

73

Boost area

75

upper limit for serial hybrid operation

77

Surface regarding parallel hybrid operation

79

Area for serial hybrid operation

81

abscissa

83

ordinate

85

Specific consumption isolines

87

Power isolines

89

Curve consumption optimal efficiency of the internal combustion engine

91

Working point curve

93

working

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102013001095 A1 [0003]
• EP 1074087 B1 [0004]
• DE 102012103292 A1 [0005]
• DE 102009019485 A1 [0006]
• DE 60223850 T2 [0007]
• DE 102007054368 A1 [0008]

Claims (10)

Method for controlling a drive device ( 3 . 203 ) of a hybrid vehicle ( 1 . 201 ), which is an internal combustion engine ( 5 . 205 ), a first electric machine ( 9 . 209 ), a second electric machine ( 11 . 211 ) and an accumulator ( 13 . 213 ), wherein the drive device is operable to drive the hybrid vehicle in the following three operating modes: a purely electrical operation in which a traction drive torque by means of the second electric machine ( 11 . 211 ) is effected while the internal combustion engine ( 5 . 205 ) is switched off; a serial hybrid mode in which the traction drive torque by means of the second electric machine ( 11 . 211 ) is effected and the internal combustion engine ( 5 . 205 ) the first electric machine ( 9 . 209 ) for generating electrical energy; a parallel hybrid operation in which a traction drive torque by means of the internal combustion engine ( 5 . 205 ), the method comprising: controlling the drive device in serial hybrid mode such that the internal combustion engine is at an operating point ( 93 ) based on a combined efficiency (η _VKM × η _EM1 ) which depends on the efficiency (η _VKM ) of the internal combustion engine and on the efficiency (η _EM1 ) of the first electric machine. Method according to claim 1, wherein the operating point ( 93 ) an extreme point of the combined efficiency for a given target power ( 87 ) and / or a given target torque. Method according to claim 1 or 2, wherein the control of the drive device ( 3 . 203 ) in serial hybrid mode includes: retrieving the operating point ( 93 ) from a given operating point curve ( 91 ), the operating points for a plurality of desired powers and / or setpoint torques defined, wherein the operating points are given by a plurality of extreme points of the combined efficiency (η _VKM × η _EM1 ) for the plurality of desired powers and / or target torques. Method according to one of the preceding claims, wherein the combined efficiency (η _VKM × η _EM1 ) is the product of the efficiency of the internal combustion engine and the efficiency of the first electric machine. Method according to one of the preceding claims, wherein the purely electrical operation is carried out if the driving speed ( 55 ) below a vehicle speed threshold ( 65 ) and a nominal drive power ( 57 ) and / or a target drive torque below an electrical operation threshold ( 67 ), wherein the purely electrical operation is further carried out if a target drive power ( 57 ) and / or a target drive torque below another electrical operation threshold ( 68 ) lie. Method according to the preceding claim, wherein the serial hybrid operation is carried out if both the driving speed ( 55 ) below the vehicle speed threshold ( 65 ) as well as a nominal drive power ( 57 ) and / or a target drive torque above the electrical operation threshold ( 67 ), wherein the serial hybrid operation is further performed if a target drive power ( 57 ) and / or a target drive torque above a cruise-dependent parallel-hybrid-operation threshold ( 69 ) lies. Method according to the preceding claim, wherein the parallel hybrid operation is carried out if both the driving speed ( 55 ) above the vehicle speed threshold ( 65 ), a nominal drive power ( 57 ) and / or a target drive torque below the vehicle speed dependent parallel hybrid drive threshold ( 69 ), as well as a nominal drive power ( 57 ) and / or a target drive torque above another electrical operation threshold ( 68 ) lies. Method according to one of the preceding claims 6 or 7, wherein the parallel hybrid operation threshold ( 69 ) is given as the sum of the drive torques, the maximum of the internal combustion engine ( 5 . 205 ) and considering a boost support of the first electric machine ( 9 . 209 ) and / or the second electric machine ( 11 . 211 ) are producible. Method according to one of the preceding claims, wherein in parallel hybrid operation at least temporarily the first electric machine ( 9 . 209 ) and / or the second electric machine ( 11 . 211 ) in addition to the traction drive power contributes. Hybrid vehicle ( 1 . 201 ), comprising: a drive device ( 3 . 203 ), which is an internal combustion engine ( 5 . 205 ), a first electric machine ( 9 . 209 ), a second electric machine ( 11 . 211 ) and an accumulator ( 13 . 213 ), wherein the drive means is operable to drive the hybrid vehicle in the following three modes of operation: a purely electric operation in which a traction drive torque is effected by means of the second electric machine while the internal combustion engine is turned off; a serial hybrid operation in which the traction drive torque is effected by the second electric machine and the internal combustion engine drives the first electric machine to generate electric power; a parallel hybrid operation in which a traction drive torque is effected by means of the internal combustion engine, wherein the hybrid vehicle further comprises a drive device control ( 6 . 206 ), which is designed to carry out a method according to one of the preceding claims.

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