DE102016221459A1 - Method for determining a rotational angle position of a crankshaft of an internal combustion engine - Google Patents

Abstract

The invention relates to a method for determining a rotational angle position (α, α) of a shaft (17), in particular of a crankshaft (17 ') of an internal combustion engine (112), comprising an electric machine (30) comprising a rotor (32) and a Stator (33), with at least one phase winding (U, V, W) is coupled directly or translated, wherein at least one phase signal (U, U, U, I, I, I) of the electric machine (30) at least one value ( W, W, W, W, W, W) which occurs in each case at least once per revolution of the rotor (32), wherein an occurrence time of at least one value (W, W, W, W, W), for determining a Rotation angle position (α) of the rotor (32) is used, characterized in that the rotational angular position (α, α) of the shaft from the rotational angular position (α) of the rotor (32) and an angular displacement (θ) is calculated. Furthermore, the invention relates to a corresponding arithmetic unit, which is set up to carry out the method, and to a computer program for carrying out the method.

Description

The present invention relates to a method for determining a rotational angular position of a crankshaft, which is coupled to an electric machine, comprising a rotor and a stator with at least one phase winding, directly or translated.

State of the art

The rotational angular position and the rotational speed of the crankshaft of an internal combustion engine are essential input variables for many functions of the electronic engine control. For their determination, marks may be provided on a body rotating with the crankshaft of the internal combustion engine at equal angular intervals. The passing of a mark as a result of the crankshaft rotation, can be detected by a sensor and passed as an electrical signal to an evaluation electronics.

For the respective rotational angle position of the crankshaft, this electronics determines the respective marked signal for the marking or measures a time difference between two markings and can determine the angular velocity and therefrom the rotational speed due to the known angular distance between two markings. In motor vehicles, in particular motorcycles, mopeds or motorcycles, the markings can be provided, for example, by teeth of a metal gear, a so-called donor wheel, which cause a change in the magnetic field as a result of their movement in the sensor. A gap of some teeth can serve as a reference mark for the detection of the absolute position.

While cars usually use 60-2 teeth (uniform distribution of 60 teeth, with two left out), motorcycles and motorcycles, for example, 36-2, 24-2 or 12-3 teeth are used. In this indirect principle of the rotational speed determination or rotational angular position determination of the crankshaft, the resolution of the rotational speed signal or the absolute detection of the rotational angular position is determined by the number of teeth and by a reliable detection of the reference mark.

In any modern vehicle with internal combustion engine, a generator is installed, which is driven by the rotation of the crankshaft and provides electrical signals that are used to supply the vehicle with electrical energy and charging the vehicle battery. The intended operation of a vehicle without this generator, is not possible or only for a short time.

A use of the electrical output variables of a driven via the crankshaft electric machine (generator), for example, in the EP 0 664 887 B1 used for speed determination. For this purpose, a phase of the generator is provided as a reference to which a pulsating DC voltage is applied. Such an arrangement can also be used to determine an estimate of the rotational angular position of the rotor of the electric machine and thereby also a rotational angular position of the crankshaft of the internal combustion engine based on the respective phase signals, which are respectively coupled directly or translated. A high-resolution speed determination or a high-resolution determination of the rotational angular position of the crankshaft and the rotor of the electric machine, however, is not realized here.

It would therefore be desirable to provide a possibility, even without the use of additional components, a high-resolution rotational angular position of the rotor of the electric machine or the crankshaft of the internal combustion engine, which is used to control an internal combustion engine to obtain.

Disclosure of the invention

According to the invention, a method with the features of claim 1 is proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

Advantages of the invention

In a method for determining a rotational angular position of a shaft, preferably a crankshaft of an internal combustion engine, in particular an internal combustion engine of a motorcycle, which with an electric machine comprising a rotor and a stator with at least one phase winding directly or translated, but with a fixed angular relation between the rotor electric machine and the crankshaft of the internal combustion engine, is at least one phase signal of the electric machine having at least one value, each at least once per revolution of the rotor electrical machine occurs, used to determine the rotational angular position of the rotor, wherein the rotational angular position of the crankshaft is calculated from the rotational angular position of the rotor and a further angular offset. In principle, the shaft can also be the shaft of the rotor, which is rotatably coupled to the rotor.

Due to the fixed coupling of the crankshaft of the internal combustion engine and the rotor of the electric machine, the rotational angle position of the crankshaft can be deduced when the rotational angular position of the rotor is known. The exact rotational position of the rotor is read from an unloaded electrical machine directly from the open circuit voltage of the electric machine, since the relative phase position of the open circuit voltage coincides with the rotational angular position of the rotor.

However, this relation does not apply to a loaded electric machine, since due to the current flow, the phase position is shifted and, correspondingly, the output voltage of the electrical machine, which corresponds to the phase voltage of at least one phase of the electrical machine, no longer coincides with the rotational angular position of the rotor , This offset of the angular position between the output voltage of the electric machine and the actual angular position of the rotor of the electric machine is commonly referred to as the pole wheel angle.

Thus, by determining the rotational angular position of the rotor and by a corresponding correction of the rotational angular position by the angular offset of the Polradwinkels a determination of the rotational angular position of the crankshaft with improved accuracy and thus higher quality can be provided.

Consequently, directly from the internal signals of the electric machine, a high-resolution determination of the rotational angle position of the crankshaft can be provided, which makes it possible to dispense with a corresponding transmitter wheel for determining the rotational angle position or rotational speed and the sensor system connected thereto. As a result, costs can be saved, which is particularly advantageous in terms of cheaper mopeds or light motorcycles. In addition, the control functions, such. As the position calculation of the injection, torque calculation or learning functions for accurately determining the TDC position and the like, can be significantly improved.

The phase signals can be obtained in various ways. Possible, for example, a consideration of the phase voltages against each other, a consideration of the phase voltages across the diodes of a connected rectifier against the potential of the output terminals, if the stator of the electric machine in star connection with tappable star point, a consideration of the output voltage of the strands against the neutral point or a comparable Evaluation of the phase currents.

In a further preferred embodiment of the invention, the values have rising edges of the phase signal and falling edges of the phase signal, or are correspondingly correlated with the rising edges of the phase signal and the falling edges of the phase signal, wherein the rising edges of the phase signal and / or the falling edges of the phase signal are used to determine the angular position of the rotor. Such flanks of the phase signal can be used in principle for a particularly simple determination of the occurrence of a characteristic value or a threshold of the phase signal, since these are particularly easy to detect in the course of a phase signal by means of a corresponding circuit. Such a circuit can be determined in particular in the form of a so-called Schmitt trigger. Thus, a rising edge and a falling edge of one of the phase signals define an angular range of the rotor which is swept by it within a time range. This angle range or angle increment can therefore be detected upon detection of an ascending and / or a falling edge of the phase signal. By taking both a rising edge and a falling edge of the same phase signal and / or rising edges and / or falling edges of different phase signals, in particular directly adjacent temporal phase signals, the accuracy of a rotational angular position of the crankshaft can be increased accordingly. It is further preferred that at least one of the phase voltage signals of the stator-side phases or at least one phase-current signal can be used to determine the rotational-angle position.

In a further preferred embodiment of the invention, the pole wheel angle angle offset is determined by a relation which has a constant and an inverse proportionality to the rotational speed of the electric machine. In this case, it is particularly preferred that the electric machine has a controller for regulating the vehicle electrical system voltage, in particular the battery voltage, wherein the controller is operated such that the angular offset is always inversely proportional to the rotational speed of the electric machine. Such a regulator, in particular a voltage regulator for a battery which is parallel to the battery can be switched, this is regulated in particular in the linear workspace. For this purpose, for example, an actuator, in particular a power transistor can be used which operates in the triode region.

By such a control, an output voltage (rectified phase voltages) can be provided, which is adjusted almost constant with respect to the battery voltage or the voltage of the electrical system. The angular offset between the output voltage and the output current at the rectifier disappears in a first approximation, since the phase-rectified rectifier in combination with a larger energy storage in the electrical system, e.g. a car battery, acts approximately as an ohmic load. Thus, it can be ensured that the angular offset or the rotor angle can be approximated by a constant and a term which is inversely proportional to the rotational speed of the electric machine. This results in a significantly simplified determination of the angular offset or the Polradwinkels, which allows an even more accurate determination of the rotational angular position of the crankshaft.

In a further preferred embodiment of the method, the rotational speed of the electric machine is determined from a time difference between at least two of the occurrence times of the values of the phase signal.

In this way, in a particularly simple manner without the use of additional sensors and a sensor wheel, the speed can be determined directly from the phase signals of the electric machine, which are present anyway.

In a further preferred embodiment of the method, the rotational angular position of the crankshaft is calculated by adding the rotational angular position of the rotor and the angular offset.

In this way, the actual rotational angular position of the crankshaft, by a simple determination of the rotational angular position of the rotor from the phase signals and the angular displacement or the Polradwinkel determined in the manner described above, can be calculated in a particularly simple manner, without the use of additional sensors or sensors Use of a sensor wheel is required.

This is particularly advantageous in the case of methods for motorcycles, in particular cost-effective small and / or light motorcycles, since in some cases no encoder wheel is present or a transmitter wheel generally has an insufficient accuracy. On the other hand can be dispensed with a donor wheel with the help of the invention, which brings a corresponding cost advantage.

Alternatively, however, an existing rotational angle position measurement by means of a transmitter wheel and a sensor can be supported and the resolution can be correspondingly improved.

In a further preferred embodiment of the method, the phase signal (U _U , U _V , U _W , I _U , I _V , I _W ) is generated by a plurality of magnetic exciters of the electric machine (30), wherein one of the magnetic exciter of the operated residual excitation that the phase signal generated by this one exciter (U _U , U _V , U _W , I _U , I _V , I _W ) assumes a value deviating from the other phase signals of the other excitation value. This is particularly advantageous since a fixed reference position can thereby be determined in order to determine the rotational angle position of the rotor and, therefrom, the rotational angular position of the crankshaft of the internal combustion engine.

In a further preferred embodiment of the invention, the phase signals of the electric machine are processed by means of an electronic circuit, in particular an engine control unit. This is particularly advantageous because no further control unit has to be implemented for the exact angular position determination of the crankshaft, it being possible to use resources which already exist anyway.

In a further preferred embodiment of the method, the rotational angle position of the crankshaft is used to control the internal combustion engine. A detection and processing of the phase signals of the electric machine by the engine control unit, and a corresponding determination of the rotational angular position of the crankshaft from the rotational angular position of the rotor and the angular displacement, can be used in accordance with the control of the ignition timing or the torque of the internal combustion engine in the control unit of the internal combustion engine controls the engine anyway. Thus, both the control of the internal combustion engine, as well as an improved determination of the angular position of the crankshaft in the engine control unit can be summarized, resulting in further synergy effects. For this purpose, the computing unit used, which is preferably designed as an engine control unit for the internal combustion engine is, a corresponding integrated circuit and / or stored on a memory computer program, which are adapted to carry out the method steps described above.

The implementation of the method in the form of a computer program, which is preferably stored on a data medium, in particular a memory in the form of software, and is available in the arithmetic unit for executing the method or the provision of an integrated circuit, in particular an ASIC, is advantageous because this causes very low costs, esp. when an executive controller is still used for other tasks, and therefore exists anyway. Suitable data carriers for providing the computer program are, in particular, magnetic, optical and electrical memories, as are frequently known from the prior art.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

list of figures

• 1 schematically shows a sensor wheel with sensor, in particular for speed determination according to the prior art;
• 2a to c show a schematic representation of a coupled to an internal combustion engine electric machine (a, b), and the associated waveforms (c);
• 3 schematically shows an electric machine, with the corresponding associated phase signals;
• 4a and 4b show possible voltage curves of the phases of a three-phase electric machine;
• 5a and 5b show a single-phase simplified equivalent circuit diagram of an electrical machine (a), and the associated phasor diagram of the phase voltage vectors (b);
• 6 shows a regulator circuit which is downstream of a rectifier of an electric machine and is adapted to control the battery voltage, and
• 7 and 8th show the course of the angular offset or the Polradwinkels on the speed of the electric machine (7) and the angular offset or the Polradwinkel over the edge time between the edges of a phase signal (8).

Embodiment (s) of the invention

In 1 are schematically a donor wheel 20 and an associated inductive sensor 10 represented, as used in the prior art for speed determination or for the approximate determination of the rotational angular position of the crankshaft. The donor wheel 20 is firmly connected to a crankshaft of an internal combustion engine and the sensor 10 is fixed in a suitable place.

The donor wheel 20 , usually made of a ferromagnetic material, has teeth 22 on the outside at a distance 21 between two teeth 22 are arranged. At one point on the outside, the sender wheel points 20 a gap 23 in the length of a predetermined number of teeth. This gap 23 serves as a reference mark for detecting an absolute position of the encoder wheel 20 ,

The sensor 10 has a bar magnet to which a soft magnetic pole pin is attached. The pole pin in turn is of an induction coil 13 surround. When the encoder wheel rotates, teeth alternate 22 and between each two teeth lying voids on the induction coil 13 of the sensor 10 past. As the donor wheel and thus the teeth 22 are made of a ferromagnetic material, a signal is induced during rotation in the coil, which between a tooth 22 and an air gap can be distinguished.

By correlating a time difference between two teeth at an angle included by these two teeth, the angular velocity and, moreover, also the corresponding angular position of the crankshaft can be approximately calculated.

At the gap 23 the induced signal in the induction coil has a different course than in the otherwise alternating with empty spaces teeth 22 , In this way, an absolute position mark, but only in relation to a full crankshaft revolution, possible.

In 2a is an internal combustion engine 112 pictured, to which directly or translated coupled an electric machine 30 Tied, the electric machine 30 through the crankshaft 17 ' the internal combustion engine 112 is driven. Thus, the speed n _{gene of} the electric machine 130 and the rotational speed n _{BKM of} the crankshaft 17 ' and the angular position α _{1 of} the rotor of the electric machine 30 and the rotational angular position α of the crankshaft 17 ' a fixed relationship to each other. The electric machine 30 In addition, a charge controller LR is assigned, the battery B within the electrical system 110 , according to the remaining capacity of the battery B, supplied with energy. Furthermore, a computing unit, in particular an engine control unit 122 provided the data over a communication connection 124 with the electric machine 30 or with the internal combustion engine 112 exchanged and set up, the internal combustion engine 112 and the electric machine 30 to control accordingly.

In 2 B is the electric machine 30 again schematically shown in enlarged form. The electric machine 30 has a shaft 17 having rotor 32 with a field winding and a stator 33 with stator winding on. It is therefore a foreign-excited machine, as is customary especially in motor vehicles. In particular, for motorcycles, especially in small and light motorcycles, however, motors are usually used with permanent magnets, ie permanent-magnet electric machine. In principle, both types of electric machines can be used within the scope of the invention, wherein in particular the method according to the invention does not depend on the use of the respective type of electric machine - permanently excited electric machine or externally excited electric machine.

Exemplary is the electric machine 30 designed as an alternator, in which three mutually phase-shifted by 120 ° phase voltage signals are induced. Such three-phase generators are commonly used as generators in modern motor vehicles and are suitable for carrying out a method according to the invention. In the context of the invention, basically all electric machines can be used independently of the number of their phases, wherein in particular the method according to the invention does not depend on the use of the respective type of electrical machine.

The three phases of the alternator 30 are denoted by U, V, W. About as plus diodes 34 and minus diodes 35 trained rectifying element, the strained at the phases voltages are rectified. Between the poles B + and B- there is thus a generator voltage U _G at which the negative pole is grounded. From such a three-phase generator 30 For example, a battery B or other consumers within the electrical system 110 provided.

In 2c are three diagrams showing the associated voltage waveforms with respect to the rotation angle of the rotor 32 the electric machine 30 demonstrate. In the upper diagram, the voltage curves at the phases U, V, W and the associated phase voltage U _{P are} entered. It is generally understood that the numbers and ranges of values given in this diagram and in the subsequent diagrams are merely exemplary, and therefore do not limit the invention in principle.

In the middle diagram, the generator voltage U _G , which is formed by the envelopes of the positive and negative half-waves of the voltage waveforms U, V, W, shown.

Finally, in the lower diagram, the rectified generator voltage U _G (cf. 2a ), together with the rms value U _{Geff of} this generator voltage U _{G- applied} between B + and B-.

In 3 is schematically the stator 33 with the phases U, V, W, and the plus diodes 34 and minus diodes 35 out 2a shown. Basically, it is understood that the rectifier elements shown here in the form of positive diodes 34 and minus diodes 35 in the case of an active rectifier also as transistors, in particular MOSFETs (metal oxide semiconductor field effect transistor) may be formed (not shown). In addition, the following nomenclature of the occurring voltages and currents is shown.

U _U , U _V , U _W denote the phase voltages of the associated phases U, V, W, as between an outer conductor and the neutral point of the stator 33 fall off. U _UV , U _VW , U _WU , denote the voltages between two phases or their associated outer conductors.

I _U , I _V , I _W denote the phase currents from the respective outer conductor of a phase U, V, W to the neutral point. I denotes the total current of all phases after rectification.

In 4a Now three phase voltages U _U , U _V , U _{W are shown} with potential reference to B- in three diagrams over time, as they occur in a generator with a Außenpolläufer with six permanent magnets. This illustration of an electric machine 30 , with a three-phase stator winding 33 is merely to be seen by way of example, wherein in principle, without limitation of generality, the method according to the invention can also be carried out on a generator with a correspondingly needs-based number of phases or permanent magnets or exciter coils. Likewise, instead of a star connection of the stator coils, it is also possible to select a triangular connection or other types of connection.

In an electric machine 30 with current output, the course of the phase voltages U _U , U _V , U _W in the first approximation is rectangular. This is explained in particular by the fact that either the plus or the minus diodes conduct in the direction of flow through the generator voltage, and therefore either approximately 15-16 volts (battery charging voltage at 12V lead-acid accumulator and voltage at plus diodes), or minus 0.7-1 Volt (voltage to negative diodes) is measured. Reference potential of the measurement is in each case mass. Other reference potentials such as the star point of the stator can also be selected. However, these deviate waveforms do not change the evaluable information, their extraction and evaluation.

In principle, the phase signals (U _U , U _V , U _W , I _U , I _V , I _W ) can be obtained in various ways. Possible, for example, a determination of the phase voltages against each other (U _UV , U _UW , U _WU ), a determination of the phase voltages across the diodes of a connected rectifier against the output terminals (B +, B-), if the stator of the electric machine in star connection with tappable star point is a consideration of the output voltage of the strands against the neutral point (U _U , U _V , U _W ) or a comparable evaluation of the phase currents.

In 4b the phase voltages U _U , U _V , U _{W are} off 4a plotted together in a diagram. Here, the uniform phase offset can be clearly seen.

During a full turn of the rotor 32 the electric machine 30 , the voltage signals are repeated six times by six magnets (in particular permanent magnets), the so-called pole pairs. Accordingly occur per phase, ie per phase voltage U _U , U _V , U _W per revolution of the rotor 32 six falling edges FL _D and six rising edges FLu (for the respective phases FL _UU , FL _VU , FL _WU and FL _UD , FL _VD , FL _WD ).

These flanks define an angular section, namely exactly the angular section which is covered by the magnets along the radial circumference of the stator. Accordingly, upon detection of the respective flanks FL _U , or FL _D , with knowledge of an absolute reference point per circulation, which is characterized, for example, by means of a reference magnet with a characteristic deviating from the other magnets of the phase voltage U _U , U _V , U _W become.

With suitable means, both the falling flanks FL _D and the rising flanks FLu can now be detected. For example, a TTL signal can be generated for each phase voltage by means of a so-called Schmitt trigger and transmitted to a control unit. The required Schmitt triggers can either be integrated in the control unit or in the control electronics, for example a control unit, a controller for the battery voltage and / or in the case of an active rectifier, in the respective generator controller or externally assigned to this. The individual TTL signals can be used in particular for the case of using a control device, in particular an engine control device 122 (see. 2a ), in each case suitably combined via one line, or by an upstream combination electronics or another, via only one data line 124 (see. 2a ).

In 4b the values of the values W _U , W _V , W _W assigned to the ends of the respective falling edges of the phase voltage U _U , U _V , U _W , which are also referred to as W _Ud , W _Vd , W _Wd . Likewise, the rising edges Flu respective values W are assigned _{Uu, Vu} W, W _Wu. These values can be used to detect a rotational angle position α _{1 of} the rotor 32 or one through the pole pairs of the stator 33 serve specified angle increments. Also, a detection of the angular position α _{1 of} the rotor 32 from the plateau areas of the phase signals or other areas in between is possible. Similarly, the values can also be used to determine the speed of the generator based on time differences Δt ₁ , Δt ₂ , Δt ₃ .

This occurs in a uniform arrangement of the six permanent magnets in the electric machine 30 , a total of 18 falling flanks FLd and thus 18 associated values per revolution at equal distances from each other. During a time difference .DELTA.t ₁ , .DELTA.t ₂ , or .DELTA.t ₃ thus an angle 360 ° / 18 = 20 ° is swept over. As already mentioned, this can also be used to detect the angular position α _{1 of} the rotor 32 are used, wherein the 20 ° determined by way of example represents the detectable angle increment. In addition, the angular velocity ω _i can be determined from this. This results from ω _i = 20 ° / Δt _i and the associated speed n _i from n _i = (ω _i / 360 ° x 60 s / min in revolutions per minute.

It is basically understood that as an alternative to the falling flanks FL _D and the rising edges for determining the rotational angle position α _{1 of} the rotor 32 as well as to determine the instantaneous speed n _{gene of} the electric machine 30 are usable. By twice the number of values per revolution, there is accordingly a higher resolution, both of the rotational angle position α _{1 of} the rotor 32 , as well as the speed n _gene . In addition, the edges of the phases can be evaluated in a variety of other ways, for example by the time intervals of the rising edges FL _U and falling edges FL _D each of the same phases or from the respective phases to each other or by the time interval of rising edges FL _U or falling flanks FL _D the same phase, or all phases together.

In addition to the rising flanks FL _U and falling flanks FL _D can for an improved resolution of the determination of the angular position α _{1 of} the rotor 32 or a speed detection n _gene , the zero crossings of the phase signals U _U , U _V , U _W are used.

The actual angular position α _{1 of} the rotor 32 and its wave 17 and thus the rotational angle position α of the crankshaft 17 ' , can be derived from the electrical signals of the electric machine 30 , In particular the phase signals U _U , U _V , U _W , or the associated phase currents I _U , I _V , I _{W determine} only with insufficient accuracy, since in the case of a loaded electrical machine 30 As a result of the current flow, there is a systematic error in the form of an angular offset between the phase angle of the phase signals U _U , U _V , U _W , or I _U , I _V , I _W and the actual rotational position α _{1 of} the rotor 32 comes. This is explained in more detail in the following figures.

wobei U der Ausgangsspannung der elektrischen Maschine 30, U_P der Leerlaufspannung der elektrischen Maschine ohne Belastung und l * jX dem Spannungsabfall U_X, der aufgrund des Stromflusses durch die elektrische Maschine und aufgrund der Reaktanz X der elektrischen Maschine im Generator abfällt, entspricht.In 5a is a schematic representation of a single-phase simplified equivalent circuit diagram of an electrical machine shown, and in 5b Accordingly, the relationship between the individual voltages or currents and their relative phase offset to each other in a vector diagram is shown. The findings determined from this single-phase equivalent circuit diagram can basically also be applied to a multi-phase electrical machine, as shown for example in the preceding description. From the single-phase equivalent circuit diagram of the electrical machine 5 a) and the associated, in 5 b), a voltage equation for a loaded electrical machine can be derived, which is as follows: $${\text{U}}_{\text{P}}=\text{jX}*\text{I}+\text{U}\text{.}$$

where U is the output voltage of the electric machine 30 , U _{P of} the open circuit voltage of the electric machine without load and l * jX the voltage drop U _X , which falls due to the current flow through the electric machine and due to the reactance X of the electric machine in the generator corresponds.

Here, the no-load voltage U _P corresponds to the electric machine 30 , the ideal induced voltage, with the angular position α _{1 of} the rotor 32 with respect to the phase. Here, corresponding to the angular offset θ, which corresponds to the Polradwinkel, equal to zero. Thus, the phase relationship of the open circuit voltage U _P exactly reflects the geometric movement of the rotor 32 again and thus gives its exact angular position - in the unloaded state of the electrical machine 30 - at.

Due to the load on the electrical machine 30 and the resulting current flow I, hurries the output voltage U of the loaded generator 30 with respect to their phase of the induced open circuit voltage U _P behind, wherein the angular offset between U and U _P by the angular displacement θ, the so-called Polradwinkel results. This is basically not dependent on the coil current I and without knowing the coil current I calculable without further notice.

In addition, the angle between output voltage U and current I results from the connected load and amounts to φ = 0 ° for a purely ohmic load. The ideal induced voltage (no-load voltage) U _{P of} the electric machine results as a product of machine constants, the excitation, and the angular velocity. In the case of a permanently excited machine, a constant excitation results from the permanent magnets used and thus an ideal induced voltage proportional to the angular velocity. From the pointer diagram 5 b) thus results for the angular offset θ: $$(\text{cos}\left(\mathrm{\theta }\right)=\left(\text{U}+\text{sin}\left(\mathrm{\phi }\right)\text{* X * I}\right){\text{/ U}}_{\text{p}}\text{,}$$

When using a linear voltage regulator 40 or a control of an actuator 42 for a voltage regulator 40 , which is formed for example in the form of a power transistor and operates in the linear range (triode region), the output voltage U of the electric machine can be 30 adjust almost constant (with respect to the battery voltage). Furthermore, the use of a rectifier ( 34 . 35 ) with a downstream battery (B) at the output of the generator 30 Approximately to a purely ohmic load, even if smaller capacities can occur in the electrical system. Hereby goes according to the angular offset between output voltage U and current I, φ, towards 0, the summand from the aforementioned formula (sin (φ) * X * I) also goes to 0 and thus disappears.

wobei sich die Konstante const. im Wesentlichen aus der konstanten Ausgangsspannung U und dem konstanten und damit nicht von der Drehzahl n_Gen abhängigen Anteil der Leerlaufspannung U_P ergibt.The open circuit voltage U _P is basically proportional to the speed n _{gen of} the electric machine 30 , Thus, assuming a substantially constant amplitude of the output voltage U and assuming that φ goes to zero and thus the second summand vanishes, the above formula simplifies the relation: $${\mathrm{\theta }}_{aprOx}={\text{cos}}^{-1}\left(\text{const}{\text{./n}}_{\text{gene}}\right)\text{.}$$

where the constant const. essentially results from the constant output voltage U and the constant and thus not dependent on the speed n _gene proportion of the open circuit voltage U _P.

wobei const.‘ neben den konstanten Faktoren von oben noch den konstanten Faktor zur Berechnung der Flankenzeit t_Gen in Sekunden aus der Drehzahl n_Gen in Umdrehungen pro Minute (rpm) enthält.If one selects a representation of the formula for θ _aprox as a function of the edge time t _Gen instead of the rotational speed n _Gen , the following relationship of θ _prox and t _gene results: $${\mathrm{\theta }}_{\text{aprox}}={\text{cos}}^{-1}\left(\text{const}{\text{. ' * t}}_{\text{gene}}\right)\text{.}$$

where const. In addition to the constant factors from the top, the constant factor for calculating the edge time t _Gen in seconds from the speed n _Gen in revolutions per minute (rpm) contains.

In the relevant time range for typical internal combustion engines from idle to about 15000 rpm, this relationship can be approximately described by a straight-line equation with a negative slope and thus enables a high computing efficiency in the application. As already indicated at the outset, the stated value ranges are merely illustrative and are not intended to limit the invention.

In such an embodiment of the battery control or a corresponding regulation of the battery voltage such that the respective actuator 42 is operated in the linear range, the angular offset θ in a first approximation even without knowledge of the current flow I can be estimated with sufficient accuracy, which is a very reliable determination of the angular displacement θ between the phase of the phase voltages Uu, Uv, Uw and the actual angular position α _{1 of} the rotor 32 allows. Accordingly, a rotational angle position α _{phase of} the rotor determined from the phase voltages U _U , U _V , U _W can be determined 32 Corresponding to the angular offset θ, which depends on the respective speed n _Gen , be corrected. From this, accordingly, the actual rotational angle position α of the crankshaft 17 the internal combustion engine or the angular position α _{1 of} the rotor 32 , be determined. These are in the case of a fixed coupling between the shaft of the rotor 32 and the crankshaft 17 in a fixed relationship to each other. Therefore, without limiting generality, α = α ₁ , but α ₁ is no longer visible in the phase signals U _U , U _V , U _W , I _U , I _V , I _W as soon as a current flows.

in besonders guter Näherung ermittelt werden. By correspondingly determining the uncorrected rotational angular position α _phase from at least one of the phase signals U _U , U _V , U _W , I _U , I _V , I _W and the above-described determination of the pole wheel angle θ, the actual angular position α _{1 can be} determined by: $${\mathrm{<figure-callout\; id="1"\; label="\alpha "\; filenames="DE102016221459A1\_0010.png,DE102016221459A1\_0015.png"\; state="\{\{state\}\}">\alpha </figure-callout>}}_{\mathrm{1}}\approx {\mathrm{\alpha }}_{\text{phase}}+\mathrm{\theta }$$

be determined in a particularly good approximation.

In 7 is the previously described relation between the angle 9 and the speed n _gene applied. This data can, for example, in the form of a map in a respective control unit 122 are deposited and the actual rotational angle position α _{1 of} the rotor 32 and thus rotational angle position α of the crankshaft 17 ' the internal combustion engine 112 be determined with significantly improved accuracy.

In 8th is the angular offset θ, or the Polradwinkel indicated over the edge time, wherein the edge time, the characteristic time ranges of the rising and falling edges FLu and FL _{D of} the phase voltages U _U , U _V , U _W (see, for example 4a ) describe. In this case, according to the above description, the course of the angular offset θ or of the rotor angle can be approximated accordingly by a straight line with a negative slope. As already indicated at the outset, the stated value ranges are merely illustrative and are not intended to limit the invention.

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Cited patent literature

• EP 0664887 B1 [0006]

Claims (13)

Method for determining a rotational angle position (α, α ₁ ) of a shaft (17), in particular of a crankshaft (17 ') of an internal combustion engine (112), comprising an electric machine (30) comprising a rotor (32) and a stator (33 ) is coupled with at least one phase winding (U, V, W), directly or translated, wherein at least one phase signal (U _U , U _V , U _W , I _U , I _V , I _W ) of the electric machine (30) at least one Value ( _WUu , W _Ud , W _Vu , W _Vd , W _Wu , W _Wd ), which occurs in each case at least once per revolution of the rotor (32), wherein an occurrence time of at least one value (W _Uu , W _Ud , W _Vu , W _Vd , W _Wu , W _Wd ) is used for determining a rotational angle position (α _phase ) of the rotor (32), characterized in that the rotational angular position (α, α ₁ ) of the shaft from the rotational angular position (α _phase ) of the rotor ( 32) and an angular displacement (θ) is calculated. Method according to Claim 1 , wherein the values ( _WUu , W _Ud , W _Vu , W _Vd , W _Wu , W _Wd ) rising edges (Fl _Uu , Fl _Vu , Fl _Wu ) of the phase signal (U _U , U _V , U _W , I _U , I _V , I _W ) and falling edges (Fl _Ud , Fl _Vd , Fl _Wd ) of the phase signal (U _U , U _V , U _W , I _U , I _V , I _W ), wherein the rising edges (Fl _Uu , Fl _Vu , Fl _Wu ) of the phase signal (U _U , U _V , U _W , I _U , I _V , I _W ) and / or the falling edges (Fl _Ud , Fl _Vd , Fl _Wd ) of the phase signal (U _U , U _V , U _W , I _U , I _V , I _W ) are used to determine the angular position (α _phase ) of the rotor (32). Method according to Claim 1 or 2 wherein the one or more phase signals (U _U , U _V , U _W , I _U , I _V , I _W ) at least one phase voltage signal (Uu, Uv, Uw) and / or at least one phase current signal (I _U , I _V , I _W ). Method according to one of the preceding claims, wherein the angular offset (θ) is determined on the basis of a relation (θ _aprox ) which has a constant (const) and an inverse proportionality to the rotational speed (n) of the electric machine (30). Method according to Claim 4 wherein the electric machine (30) has a controller (40) for controlling the vehicle electrical system voltage, wherein the controller (40) is operated such that the cosine of the angular offset (θ) is always inversely proportional to the rotational speed (n) of the electric machine (30 ). Method according to Claim 4 or 5 wherein the rotational speed (n) is determined from a time difference (Δt ₁ , Δt ₂ , Δt ₃ ) of at least two occurrence _{times of} the values (W _Uu , W _Ud , W _Vu , W _Vd , W _Wu , W _Wd ). Method according to one of the preceding claims, wherein the rotational angular position (α) of the shaft by adding the rotational angular position (α _phase ) of the rotor (32), preferably from at least one phase signals (U _U , U _V , U _W , I _U , I _V , I _W ), and the angular displacement (θ) is calculated. Method according to one of the preceding claims, wherein the phase signal (U _U , U _V , U _W , I _U , I _V , I _W ) by a plurality of magnetic exciter of the electric machine (30) is generated, wherein one of the magnetic exciter of the operated residual excitation that the phase signal generated by this one exciter (U _U , U _V , U _W , I _U , I _V , I _W ) assumes a value deviating from the other phase signals of the other excitation value. Method according to one of the preceding claims, wherein the one or more phase signals (U _U , U _V , U _W , I _U , I _V , I _W ) of the electric machine (30) by means of an electronic circuit, in particular an engine control unit (122) processed become. Method according to one of the preceding claims, wherein the rotational angle position (α, α ₁ ) of the shaft (17) for controlling the internal combustion engine (112) is used. Arithmetic unit, preferably an engine control unit (122) for an internal combustion engine (12), which is configured by a corresponding integrated circuit and / or by a stored on a memory computer program to perform a method according to any one of the preceding claims. Computer program that causes a computing unit, a method according to one of Claims 1 to 10 when executed on the computing unit. Machine-readable storage medium with a computer program stored thereon Claim 12 ,

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