DE102019203591A1 - Method for operating an arrangement with an internal combustion engine and an electrical machine - Google Patents

Abstract

The invention relates to a method for operating an arrangement with an internal combustion engine with a crankshaft and an electric machine coupled therewith in a torque-transmitting manner, which is electrically connected to an energy storage device, wherein in a predetermined operating range of the internal combustion engine at a predetermined crankshaft angle (φ) within a working cycle (A) of a cylinder of the internal combustion engine, a current value (nmax) of the speed (n) of the crankshaft is determined, and the electric machine is controlled in such a way that the speed (n) is increased by a torque transmission between the electric machine and the crankshaft when the current value (nmax) is smaller than a corresponding comparison value (n), and / or is reduced if the current value (nmax) is greater than the comparison value (n).

Description

The present invention relates to a method for operating an arrangement having an internal combustion engine with a crankshaft and an electric machine coupled therewith in a torque-transmitting manner, which is electrically connected to an energy store, as well as a computing unit and a computer program for its implementation.

State of the art

In internal combustion engines, the kinetic energy generated in the working cycle increases the speed, while the subsequent exhaust, intake and compression cycles reduce the speed again. This also results in certain speed fluctuations within a working cycle of a cylinder of an internal combustion engine.

The higher the number of cylinders of an internal combustion engine, in which the work cycles are then also offset from one another, the more likely it is that such speed fluctuations can be at least partially compensated for.

In the case of internal combustion engines with a small number of cylinders, such as are used in particular in motorcycles, it is therefore less possible to compensate for these speed fluctuations.

Disclosure of the invention

According to the invention, a method for operating an arrangement with an internal combustion engine and an electrical machine as well as a computing unit and a computer program for its implementation are proposed with the features of the independent claims. Advantageous configurations are the subject of the subclaims and the description below.

A method according to the invention is used to operate an arrangement with an internal combustion engine with a crankshaft and an electric machine coupled to it in a torque-transmitting manner, which is electrically connected to an energy store, for example a battery. An internal combustion engine with a maximum of two cylinders, preferably precisely one cylinder, such as is typically used in motorcycles, comes into consideration as the internal combustion engine.

Although the proposed method is described below in particular with reference to an internal combustion engine with (precisely) one cylinder, this can also be transferred to internal combustion engines with two or more cylinders and can be used there.

In addition to the speed fluctuations in internal combustion engines mentioned at the beginning, it has been found that the kinetic energy generated in a cylinder in a work cycle - and thus also the associated speed change - fluctuates statistically. This is due, for example, to different amounts of air that are supplied and the quality of the respective combustion. This then has a corresponding effect on the following cycles, including the following work cycles. In particular in the case of such internal combustion engines with a small number of cylinders, however, this - as well as the speed fluctuations that are usual anyway - can be compensated less well, so that there is an overall high speed fluctuation there.

It is now possible to regulate the internal combustion engine to as constant a speed as possible by adjusting the amount of air supplied to the cylinder and / or by adjusting an ignition point. This applies in particular to idle operation. Here, however, speed-regulating action can only be taken once per cylinder and working cycle, which does not allow particularly fast or good control of the speed, in particular not in internal combustion engines with a small number of cylinders.

It is now proposed that a current value of the rotational speed of the crankshaft be determined in a predetermined operating range of the internal combustion engine at a predetermined crankshaft angle within a working cycle of a cylinder of the internal combustion engine. In addition, the electric machine is controlled in such a way that the rotational speed is increased by a torque transmission between the electric machine and the crankshaft if the current value is less than a corresponding comparison value (i.e. also in the predetermined operating range of the internal combustion engine at the predetermined crankshaft angle), and / or is reduced if the current value is greater than the comparison value.

A crankshaft angle corresponding to a speed maximum within the work cycle is preferably used as the predetermined crankshaft angle within the work cycle. Such a maximum speed typically occurs at the end of the work cycle.

In particular, an energy difference between an energy currently provided by the internal combustion engine (i.e. in particular the energy generated in the work cycle that is converted into kinetic energy) and a comparison energy value can also be determined on the basis of the current value and the comparison value for the speed, the electrical machine being controlled in this way becomes, that this energy difference is compensated by the torque transmission between the electric machine and the crankshaft.

Such energy can be determined, for example, using a model of the internal combustion engine, taking into account the speed. For a more detailed explanation of this, reference is made to the remarks below.

In the context of this method, a mean value of the speed (in the specified operating range of the internal combustion engine at the predetermined crankshaft angle) over a large number of work cycles can be considered as a comparison value for the speed. The mean value can be calculated arithmetically or otherwise; a median value can also be considered. Instead of an averaging, a model can also be used to obtain such a comparison value as an average or usual value. The same then applies to the energy comparison value.

As can be seen from the above explanations, a current speed at the predetermined crankshaft angle will typically be below or above the comparison value. An accelerating or braking torque can now be exerted on the crankshaft by suitable control of the electrical machine. How exactly or how strongly accelerating or braking the electrical machine has to be controlled for this purpose can be determined in particular on the basis of the energy difference mentioned.

The electric machine can be controlled, for example, in such a way that, starting from a current point in time at which the energy difference was calculated, up to a crankshaft angle corresponding to a gas change top dead center, it exerts torque on the crankshaft uniformly or in some other way. Depending on the required energy output or energy consumption, this can also take place beyond the gas change top dead center.

With the proposed method, the fluctuations in speed that arise due to the statically uneven combustion processes can now be compensated particularly effectively and, above all, particularly quickly. In comparison to a speed-regulating intervention by adapting the amount of air or ignition timing, the electrical machine can be controlled much faster.

In general, an electrical machine can be operated as a motor or generator, i.e. electrical energy can be taken from the energy store and delivered to the crankshaft as mechanical energy as accelerating torque, or mechanical energy can be taken from the crankshaft as braking torque and fed to the energy store as electrical energy. Overall, you can vary between full motor and full generator power.

However, it must now also be taken into account that the electrical machine is typically used to generate electrical energy that is to be fed to the energy store and / or to an on-board network that is electrically connected to it. The control of the electrical machine, as suggested above, i.e. that the crankshaft is accelerated or braked, can now be superimposed on the (usual) operation in which electrical energy is provided.

In this case, it is not absolutely necessary to operate the electric machine with a motor; rather, an accelerating effect on the crankshaft can also be achieved in that less energy is generated for the energy store or the on-board network. In relative terms - in relation to the braking effect of the electrical machine generated during regular operation - an accelerating effect can still be achieved.

In this respect, it is particularly preferred if the electrical machine continues to be controlled in such a way that a voltage of the energy store and / or of an on-board network electrically connected to it is kept within a predefined setpoint range. As an alternative or in addition to the voltage, a state of charge of the energy store can also be used. In particular, an actual value for the voltage or the state of charge can be kept within the target range or varied. While it has been customary up to now to regulate the voltage in the vehicle electrical system to a specific target value, the use of a target range means that certain variations in the voltage are possible. As a result of the aforementioned control of the electrical machine, in which the crankshaft is accelerated or braked, a change in the voltage provided also follows.

In particular, especially within the scope of a fast control path, the speed is regulated to a predetermined value as a control value by means of a setpoint for the voltage of the energy store and / or an electrical system connected to it or the state of charge of the energy store. In addition, it is preferred that if the setpoint of the voltage of the energy store and / or of the electrical system connected to it or the state of charge of the Energy store reaches or exceeds an edge of the target range, the target value of the voltage or the state of charge is set by changing a torque generated by the internal combustion engine to a predetermined value within the target range, in particular a value that is centrally located in the target range. In this way, the setpoint torque of the internal combustion engine is tracked in a slower control path, continuously remaining (mean) speed deviations and a changing energy requirement of the electrical system.

Overall, a multivariable controller is provided which has as input variables a power of the electrical machine and a torque generated or provided by the internal combustion engine, and the voltage or the state of charge of the energy store or the voltage of the electrical system connected to it and the speed as output variables , especially as idle speed. It is taken into account that the voltage or charge is set by changing the power of the electric machine, but at the same time there is also a cross coupling to the speed, since the speed is increased by increasing the power of the electric machine (especially in generator mode) decreases (which in turn affects the performance of the electrical machine). The rotational speed is essentially influenced by the torque of the internal combustion engine, with a changed rotational speed also changing the power of the electrical machine in turn and this then having an influence on the voltage or the state of charge.

On the one hand, the two control paths mentioned allow the speed to be controlled as effectively and specifically as possible, but if necessary the voltage or the state of charge can also be corrected so that it remains within the specified target range. Overall, this also has a positive effect on any pollutant emissions.

The power of the electrical machine is advantageously changed only once per working cycle and / or not during an injection process and / or not during charging of an ignition coil of the internal combustion engine. It can thus be achieved that the combustion or the combustion process itself is influenced as little as possible.

In particular, so-called delayed (unexpectedly bad) burns and the associated drops in speed occur when the internal combustion engine is idling. Burns that are too good, on the other hand, occur less frequently and only with a slight increase in speed.

Since the greatest possible efficiency of the on-board electrical system can be achieved if the power output of the electrical machine is kept as constant as possible, a torque control intervention by the electrical machine in the event of excessive combustion can be dispensed with in favor of this efficiency. Instead, a slight speed overshoot is accepted in these cases and torque intervention with the electrical machine is only carried out in the case of delayed combustion in favor of speed stability. In other words, the electric machine is preferably controlled in such a way that the rotational speed is increased by a torque transmission between the electric machine and the crankshaft if the current value is less than a corresponding comparison value, but not reduced if the current value is greater than Comparison value is.

Idle operation is particularly preferably used as the predetermined operating range of the internal combustion engine. Since strong speed fluctuations occur particularly in idle operation, better idling can be achieved with the proposed method. In particular, the idling speed can even be reduced in this way. However, the proposed method is also suitable for other operating ranges, in particular those with a low load and / or low speed (but above the idling speed).

Overall, an adjustment of the ignition angle for speed control can thus be dispensed with and this can thus be set constantly to the optimal value. This immediately results in more efficient or stronger combustion. In this way, the amount of air and fuel per combustion could be reduced accordingly, thereby lowering the consumption and emissions of the internal combustion engine.

In particular, the energy store, which is designed as a battery, and also its states, for example on the computing unit, can be modeled, if necessary by additional measurement of the battery current, and the state of charge of the energy store can thus be determined. In this case, the regulation presented above can, as already mentioned, regulate the state of charge instead of the voltage, or the regulation can be expanded so that the voltage (charge voltage) is regulated within a setpoint range and a desired state of charge is regulated at the same time.

A computing unit according to the invention, e.g. a control unit of a motor vehicle is set up, in particular in terms of programming, to carry out a method according to the invention.

The implementation of a method according to the invention in the form of a computer program or computer program product with program code for performing all method steps is advantageous, since this causes particularly low costs, in particular if an executing control device is also used for other tasks and is therefore available anyway. Suitable data carriers for providing the computer program are, in particular, magnetic, optical and electrical memories such as hard drives, flash memories, EEPROMs, DVDs, etc. A program can also be downloaded via computer networks (Internet, intranet, etc.).

Further advantages and configurations of the invention emerge from the description and the accompanying drawing.

The invention is illustrated schematically in the drawing using exemplary embodiments and is described below with reference to the drawing.

• 1 zeigt schematisch eine Anordnung mit Brennkraftmaschine und elektrischer Maschine, mit der ein erfindungsgemäßes Verfahren durchführbar ist.
• 2 zeigt schematisch einen Drehzahlverlauf einer Brennkraftmaschine zur Erläuterung eines erfindungsgemäßen Verfahrens in einer bevorzugten Ausführungsform.
• 3 zeigt schematisch einen Ablauf eines erfindungsgemäßen Verfahrens in einer weiteren bevorzugten Ausführungsform.
• 4 zeigt schematisch einen Ablauf eines erfindungsgemäßen Verfahrens in einer weiteren bevorzugten Ausführungsform.

Brief description of the drawings

• 1 shows schematically an arrangement with an internal combustion engine and an electrical machine with which a method according to the invention can be carried out.
• 2 shows schematically a speed curve of an internal combustion engine to explain a method according to the invention in a preferred embodiment.
• 3 shows schematically a sequence of a method according to the invention in a further preferred embodiment.
• 4th shows schematically a sequence of a method according to the invention in a further preferred embodiment.

Embodiment (s) of the invention

In 1 is schematically an arrangement 100 with an internal combustion engine 110 and an electric machine 120 shown, with which a method according to the invention can be carried out. The internal combustion engine 110 is exemplary as an internal combustion engine with one cylinder 111 and with crankshaft 115 educated.

The electric machine 120 is with the crankshaft 115 - and thus also with the internal combustion engine 110 - Coupled to transmit torque. In addition, the electric machine is 120 with an energy store 130 , which can be a battery, for example, is electrically connected, ie electrical energy can be drawn from the electrical machine 120 to energy storage 130 flow and vice versa. In addition, an on-board network can be electrically connected to the energy store 130 be connected.

By means of a computing unit designed as a control unit 140 can the electric machine 120 be controlled accordingly, that is, a torque-absorbing or generator operation can be carried out in which electrical energy from the electrical machine 120 to energy storage 130 flows. Likewise, if necessary, a torque-generating or motor-driven operation can be carried out in the electrical energy from the energy store 130 to the electric machine 120 flows.

On or for the crankshaft 115 is also an angle sensor 116 provided, by means of which a current crankshaft angle and, if necessary, also a speed is detected and the control unit 140 can be fed.

In 2 is a schematic of a speed curve of an internal combustion engine, in particular that in 1 internal combustion engine shown. For this purpose, a speed n is plotted against a time t. The speed curve shown here corresponds to the speed curve in idle mode. Because the internal combustion engine has only one cylinder, there are relatively large fluctuations in speed.

A total of three work cycles A can be seen, each with a work, discharge, intake and compression cycle. An ignition top dead center ZOT and a gas exchange top dead center GOT are shown by way of example. Within one work cycle, a minimum speed occurs approximately at TDC and a maximum speed occurs later at approximately 90 ° to 180 ° crankshaft angle. With GOT the speed is at an average value.

In addition to the speed fluctuations within a work cycle, it can also be seen that the maximum (and also the minimum) speed within a work cycle varies between the work cycles. Various values for the maximum speed are denoted by n _{max, soll} and nmax. As explained above, this is due, for example, to statistical deviations in the combustion processes.

By way of example and to explain the proposed method, the value designated by n _{max, should} correspond to a mean value and thus serve as a comparison value.

The aim of regulation or control within the framework of the proposed method is, for example, to set the speed at the beginning of the inlet opening to the same value in every work cycle to regulate. The point to open the inlet is just before the GOT. The starting point is then, for example, a speed maximum at a predetermined crankshaft angle φ ₁ , for example at 180 ° CA after ZOT, that is to say, for example, the value nmax.

By comparison with a comparison value or an expected _maximum speed n _{max, it} is calculated how much energy too much or too little was generated by the combustion in comparison to a median or typical combustion. If too much energy has been generated, the electrical machine stores the excess energy in the energy store via a controller, for example for the time until GOT. If too little energy was generated, this energy is fed into the system via the electrical machine.

Typically, particularly good burns can only bring a little more energy into the system than on average, while bad or delayed burns, on the other hand, can bring significantly less energy into the system than on average. Thus, in the context of the proposed method, the crankshaft is acted on by accelerating rather than braking.

The calculation of the energy difference ΔE can be done quadratically, for example, it is then calculated as: $$\Delta \mathrm{E.}={\mathrm{C.}}_T\cdot \left(n_{\text{Max}}^2-n_{\text{Max},sOll}^2\right).$$

The constant C _T here correlates with the moment of inertia of the internal combustion engine at the crankshaft angle φ ₁ and can, for example, be learned in the system or appropriately applied.

In order to obtain a current comparison value n _max, setpoint _{, i} , a computationally efficient averaging of all previously measured values can take place, for example. The comparison value is then obtained with the aid of a recursive filter as $$n_{\text{Max},sOll,i}=\frac{n_{\text{Max},\text{i}}+\left(\mathrm{M.}-1\right)\cdot n_{\text{Max},sOll,i-1}}{\mathrm{M.}}.$$

Other averaging calculations are also possible as long as a sufficiently strong averaging is used. Possible filter factors for the above-mentioned equation are, for example, M = 50 to M = 100. However, smaller / larger values can also be preferred depending on the target system. Here, the first measured speed is equated with the first averaged speed.

A control request for the electrical machine can be derived from the calculated energy difference ΔE. The missing or excess energy is electrically compensated for up to a further (kept constant) crankshaft angle φ ₂ in the same working cycle. A suitable position here can be, for example, a 360 ° crankshaft angle according to φ ₁ .

The position is advantageously chosen such that a constant battery voltage is realized during the duration of the injection and the ignition, that is to say that the electrical machine keeps its output power as constant as possible and φ ₂ does not fall within these two ranges.

wobei mit n_soll eine mittlere Drehzahl, insbesondere Leerlaufdrehzahl, bezeichnet ist. Der Faktor „6°“ im Nenner resultiert dabei aus einer Verwendung der Drehzahl in rpm bzw. Umdrehungen pro Minute (U/min). Bei einer Frequenz (1/s) müsste stattdessen der Faktor „360°“ verwendet werden. Die Winkel werden dabei jeweils in Grad, nicht aber in rad angegeben. Eine hierbei auftretende Ungenauigkeit durch Verwendung des Drehzahlsollwerts statt der realen mittleren Drehzahl während des Intervalls, die zum Zeitpunkt bei φ₁ noch unbekannt ist, kann vernachlässigt werden. Aus dem berechneten Zeitintervall lässt sich die notwendige Leistung P der elektrischen Maschine während dieser Zeit berechnen zu: $$P=\frac{\Delta E}{\Delta t}.$$

To compensate for the energy difference, the corresponding amount of energy must be applied or removed electrically during the crankshaft angle interval from φ ₁ to φ ₂ . For this purpose, the time interval Δt, which is necessary to cover the crankshaft angle interval, is calculated with: $$\Delta t=\frac{{\phi }_2-{\phi }_1}{\mathrm{6th}°\cdot n_{sOll}},$$

where n _soll denotes an average speed, in particular idling speed. The factor “6 °” in the denominator results from using the speed in rpm or revolutions per minute (rpm). With a frequency (1 / s), the factor “360 °” would have to be used instead. The angles are given in degrees, but not in rad. Any inaccuracy that occurs here due to the use of the speed setpoint instead of the real average speed during the interval, which is still unknown at the time at φ ₁ , can be neglected. The required power P of the electrical machine during this time can be calculated from the calculated time interval: $$P=\frac{\Delta \mathrm{E.}}{\Delta t}.$$

In order to supply the on-board network or the energy store with electrical energy, a corresponding output of the electrical machine must constantly be set as a generator. Therefore, the electrical power calculated above should be added as an offset to a basic power.

Since the internal combustion engine is set, typically by the engine control unit, in such a way that the desired speed n setpoint _is maintained on average, the average output power of the electrical machine changes only to a limited extent due to the efficiency of the electrical energy conversion in the energy storage device and electrical machine and control hardware.

If no torque or power calculation of the electrical machine is used, but rather a regulation of the rotor angle, a rotor angle difference Δδ can be calculated directly from the energy difference by means of a conversion factor, even if the inaccuracies that occur in this case are neglected. The following applies: $$\Delta \delta ={\mathrm{C.}}_P\cdot \Delta \mathrm{E.}={\mathrm{C.}}_P\cdot {\mathrm{C.}}_T\cdot \left(n_{\text{Max}}^2-n_{\text{Max},sOll}^2\right).$$

The two constants can be combined into a combined constant C: $$\Delta \delta =\mathrm{C.}\cdot \left(n_{\text{Max}}^2-n_{\text{Max},sOll}^2\right).$$

The calculated pole wheel angle offset Δδ is added to the currently set pole wheel angle and results on average, as in the power case above, at zero, since the internal combustion engine can maintain the target speed on its own on average.

In 3 a sequence of a method according to the invention is shown schematically in a preferred embodiment. As already mentioned above, a multivariable controller can be used within the framework of the proposed method.

This is shown as an example, namely with the input variables of the power P of the electrical machine and the torque M generated or provided by the internal combustion engine, and with the output variables of the voltage U of the energy store or the electrical system connected to it and the speed n, in particular as Idle speed.

It is also expressed that the voltage U is set by changing the power P, but at the same time there is also a cross coupling to the speed n, since the speed increases due to an increase in the power output of the electric machine (especially in generator mode) decreases (which in turn affects the performance of the electrical machine). The torque M essentially influences the speed n, with a changed speed n in turn changing the power P and this then has an influence on the voltage U.

In 4th a sequence of a method according to the invention is shown schematically in a preferred embodiment. The voltage U is usually regulated via the power P of the electrical machine. This can be set, for example, via the correcting variable rotor angle.

In the context of the proposed method, however, it is now provided not to regulate to a constant voltage or a desired value of the voltage, but to keep the voltage in a suitable desired range. In particular in the idling operating range, a new setpoint for the voltage and a new value for the torque of the internal combustion engine are calculated by comparing the setpoint speed with the actual speed using a suitable controller or algorithm.

_To this end, in particular in the context of a fast control path, n for the stabilization of the speed, the control means to a target rotational speed n, the command value U _{is to be} used as a manipulated variable of the voltage. At too high a speed is increased to the voltage of the reference value U _soll. To achieve this, the power output of the electric machine is then increased and the speed decreases. If the speed is too low, the setpoint U of the voltage and thus the power output of the electrical machine are reduced or even motorized power is supplied, and the speed increases.

The voltage can be adjusted to the corresponding setpoint using the power of the electrical machine as a control value in the sense of a subordinate controller. Control without regulation is also conceivable here. With regard to the specific procedure for setting the power of the electrical machine, reference is made to the statements above.

The nominal value U _{soll of} the voltage may in particular only be allowed within a nominal range U _B = [U _{soll, min} ; U _{should, max} ] be varied: $$U_{sOll,\text{min}}<U_{sOll}\le U_{sOll,\text{Max}}.$$

The minimum value U _{should, min} can be, for example, 12.5 V and the maximum value U _{should, max,} for example, be 14.3 V. Before or when these limits are exceeded or when an edge of the setpoint range U _{B is} reached or exceeded, the torque M of the internal combustion engine can be changed in a slow path and - thus - the setpoint U _should be adjusted _to the voltage so that the new setpoint is centrally located in the target area U _B. As already mentioned, the speed can be increased by increasing the torque, which increases the power of the electrical machine and thus the voltage. The same applies to a reduction.

The proposed method allows the internal combustion engine to be kept largely at a constant operating point when regulating the speed, in particular the idling speed, by using the electric machine, which has positive effects on emissions and consumption.

Claims (13)

Method for operating an arrangement (100) with an internal combustion engine (110) with a crankshaft (115) and an electric machine (120) coupled to it in a torque-transmitting manner, which is electrically connected to an energy store (130), with the internal combustion engine (110 ) at a predetermined crankshaft angle (φ ₁ ) within a working cycle (A) of a cylinder (111) of the internal combustion engine, a current value (nmax) of the speed (n) of the crankshaft is determined, and the electric machine (120) is controlled in such a way that through a torque transmission between the electrical machine (120) and the crankshaft, the speed (n) is increased if the current value (nmax) is less than a corresponding comparison value (n _{max, soll} ), and / or is reduced if the current value (nmax) is greater than the comparison value (n _{max, soll} ). Procedure according to Claim 1 , with a crankshaft angle corresponding to a speed maximum within the working cycle being used as the predetermined crankshaft angle (φ ₁ ) within the working cycle. Procedure according to Claim 1 or 2 , with the current value (nmax) and the comparison value (n _{max, soll} ) of the speed being used to determine an energy difference between an energy currently provided by the internal combustion engine and a comparison energy value, and the electrical machine (120) is controlled in such a way that the torque transmission between the electric machine (120) and the crankshaft (115) this energy difference is compensated. Method according to one of the preceding claims, wherein the electric machine (120) is controlled in such a way that the rotational speed (n) is increased by a torque transmission between the electric machine (120) and the crankshaft if the current value (nmax) is less than corresponding comparison value (n _max, target) is, but is not reduced if the current value (nmax) is greater than the comparison value (n _max, target). Method according to one of the preceding claims, wherein the electrical machine (120) is further controlled in such a way that a voltage (U) of the energy store (130) and / or an on-board network electrically connected to it and / or a state of charge of the energy store is within a predetermined target range ( U _B ) is held. Procedure according to Claim 5 , the speed (n) being adjusted to a predetermined value (n _soll ) as a control value by means of a setpoint (U _soll ) for the voltage of the energy store and / or an electrical system connected to it or the state of charge of the energy store. Procedure according to Claim 6 , where, if the setpoint (U _soll ) of the voltage of the energy store and / or the on-board network or the state of charge of the energy store reaches or exceeds an edge of the set range (U _B ), the setpoint (U _soll ) of the voltage or the state of charge falls below Change of a torque (M) generated by the internal combustion engine (110) is set to a predetermined value within the target range (U _B ), in particular a value which is centrally located in the target range. Method according to one of the preceding claims, wherein a power (P) of the electrical machine (120) changes only once per working cycle and / or not during an injection process and / or not during charging of an ignition coil of the internal combustion engine (110). Method according to one of the preceding claims, wherein idling operation is used as the predetermined operating range of the internal combustion engine (110). Method according to one of the preceding claims, wherein an internal combustion engine with at most two cylinders, preferably exactly one cylinder, is used as the internal combustion engine. Computing unit (140) which is set up to carry out all method steps of a method according to one of the preceding claims. Computer program that causes a processing unit (140) to perform all method steps of a method according to one of the Claims 1 to 10 to be carried out when it is executed on the computing unit (140). Machine-readable storage medium with a computer program stored thereon Claim 12 .

Images