DE102020214752A1 - Method for optimizing operation of an electronically commutated motor and optimized motor - Google Patents

Abstract

The invention relates to a method (100) for optimizing an operation of an electronically commutated motor (200), comprising: determining (101) an actual torque MNOW with an actual torque ripple WNOW of the motor (200) in a loaded state; determining (103) a Target torque MNEw with a target torque ripple WNEW of the loaded motor (200), the target torque ripple WNEW being smaller than the actual torque ripple WNOW; determining (105) a target exciter current INEW, the target exciter current INEW in the loaded motor (200) the target torque MNEw with the target torque ripple WNEWh. The invention further relates to a motor (200) with optimized torque ripple.

Description

The invention relates to a method for optimizing operation of an electronically commutated motor and a correspondingly optimized motor.

State of the art

For electronically commutated machines or motors, the NVH noise vibration harshness behavior is an increasingly important component for assessing the qualitative functionality of such machines and motors. The improvement in the qualitative function of electronically commutated machines or motors thus includes reducing the noise level of the motor. This is mainly caused by torque ripple, especially in actively loaded electronically commutated motors.

The best results of the project of reducing the torque ripple are obtained when considering the real parameters of the magnetic circuit, especially under the influence of the load condition or current. The current together with the flux linkage, or in other words the maximum field potential of the permanent magnet synchronous machine, is the most important component of the torque generation in the EC machine.

It is therefore an object of the invention to provide an improved method for optimizing operation of an electronically commutated motor and a correspondingly optimized motor.

This object is solved by the method for optimizing an operation of an electronically commutated motor and by the motor of the independent claims. Advantageous configurations are the subject matter of the subordinate claims.

• Bestimmen eines Ist-Drehmoments M_NOW mit einer Ist-Drehmomentwelligkeit W_NOW des Motors in einem belasteten Zustand;
• Bestimmen eines Soll-Drehmoments M_NEW mit einer Soll-Drehmomentwelligkeit W_NEW des belasteten Motors, wobei die Soll-Drehmomentwelligkeit W_NEW kleiner ist als die Ist-Drehmomentwelligkeit W_NOW;
• Bestimmen eines Soll-Erregerstroms I_NEW, wobei der Soll-Erregerstrom I_NEW im belasteten Motor das Soll-Drehmoment M_NEW mit der Soll-Drehmomentwelligkeit W_NEW hervorruft.

According to one aspect of the invention, a method for optimizing an operation of an electronically commutated motor is provided, the method comprising:

• determining an actual torque M _NOW with an actual torque ripple W _NOW of the engine in a loaded condition;
• determining a target torque M _NEW with a target torque ripple W _NEW of the loaded motor, wherein the target torque ripple W _NEW is less than the actual torque ripple W _NOW ;
• Determining a target excitation current I _NEW , with the target excitation current I _NEW causing the target torque M _NEW with the target torque ripple W _NEW in the loaded motor.

As a result, the technical advantage can be achieved that an improved method for optimizing operation of an electronically commutated motor can be provided, which allows optimization of torque ripple of the electronically commutated motor. By optimizing the torque ripple, in which a target torque is determined such that a target torque ripple of the target torque is smaller than an actual torque ripple of an actual torque of a motor operated in a loaded state, noise of the motor can be reduced due to the reduced torque ripple and thus a noise vibration harshness NVH of the engine can be improved. By determining the desired target torque with a correspondingly reduced target torque ripple, taking into account the actual torque of the motor operated under load, it is possible to determine the reduced torque ripple as precisely and simply as possible and, associated with this, optimize the operation of the electronically commutated motor with reduced noise development be reached.

• Ansteuern des Motors mit dem Soll-Erregerstrom I_NEW;
• Messen eines weiteren Ist-Erregerstroms I_NOW des mit dem im Schritt bestimmten Soll-Erregerstrom I_NEW angesteuerten Motors;
• Berechnen eines weiteren Ist-Drehmoments M_NOW mit einer weiteren Ist-Drehmomentwelligkeit W_NOW unter Berücksichtigung des gemessenen weiteren Ist-Erregerstroms I_NOW gemäß einer motorspezifischen Relation M=k_M*I, wobei k_M eine motorspezifische Drehmomentkonstante ist;
• Vergleichen der Soll-Drehmomentwelligkeit W_NEW mit der weiteren Ist-Drehmomentwelligkeit W_NOW; und
• Iteratives Ausführen der genannten Verfahrensschritte, falls eine Differenz zwischen der Soll-Drehmomentwelligkeit W_NEW und der weiteren Ist-Drehmomentwelligkeit W_NOW einen vorbestimmten Grenzwert überschreitet.

According to one embodiment, the method further comprises:

• Driving the motor with the target excitation current I _NEW ;
• measuring a further actual excitation current I _NOW of the motor driven with the target excitation current I _NEW determined in step ;
• Calculating a further actual torque M _NOW with a further actual torque ripple W _NOW taking into account the measured further actual excitation current I _NOW according to a motor-specific relation M=k _M *I, where k _M is a motor-specific torque constant;
• Comparing the setpoint torque ripple W _NEW with the further actual torque ripple W _NOW ; and
• Iterative execution of the method steps mentioned if a difference between the setpoint torque ripple W _NEW and the further actual torque ripple W _NOW exceeds a predetermined limit value.

In this way, the technical advantage can be achieved that the torque ripple of the electronically commutated motor can be reduced as simply and efficiently as possible. For this purpose, the electronically commutated motor is switched on with the specified target excitation current controls and an actual actual excitation current of the motor driven with the target excitation current is determined by corresponding current measurements. Based on the actual excitation current determined by measurement, a corresponding actual torque is calculated with a corresponding actual torque ripple in a motor-specific relationship between torque and excitation current. If the calculated actual torque ripple deviates from the previously determined setpoint torque ripple by more than a previously determined limit value, the method is continued iteratively. For this purpose, based on the measured actual excitation current and the actual torque calculated therefrom, a new target torque with a new target torque ripple and a target excitation current associated therewith is determined. The motor is controlled again according to this excitation current and further measured values of the actual excitation current are recorded. Based on this, an actual torque and an associated actual torque ripple are calculated again, which in turn are compared with the previously determined target torque ripple. The iterative continuation of the method is terminated as soon as the difference between the desired setpoint torque ripple and the actual torque ripple that is actually present corresponds to or falls below the predetermined limit value. By iteratively determining the excitation currents that are suitable for generating a desired low torque ripple, the operation of the electronically commutated motor can be optimized quickly and precisely, in which it has the lowest possible torque ripple and, associated with it, the lowest possible noise development.

• Berechnen des Soll-Erregerstroms I_NEW unter Berücksichtigung des Soll-Drehmoments M_NEW gemäß einer motorspezifischen Relation M_NEW =k_M* I_NEW, wobei k_M eine motorspezifische Drehmomentkonstante ist.

According to one embodiment, the determination of the target excitation current I _NEW includes:

• Calculation of the setpoint excitation current I _NEW taking into account the setpoint torque M _NEW according to a motor-specific relation M _NEW =k _M * I _NEW , where k _M is a motor-specific torque constant.

This can achieve the technical advantage that the target excitation current can be determined as precisely as possible via the known motor-specific relation M=k _M *I between the torque M and the excitation current I via the known motor-specific torque constant k _M . The relation M=k _M *I applies both to the actual torque M _NOW and the actual excitation current I _NOW , M _NOW =k _M * I _NOW , and to the target torque M _NEW and the target excitation current I _NEW , M _NEW =K _M * I _NEW .

• Messen eines Ist-Erregerstroms I_NOW des Motors in einem belasteten Zustand; Berechnen des Ist-Drehmoments M_NOW unter Berücksichtigung des gemessenen Ist-Erregerstroms I_NOW gemäß einer motorspezifischen Relation M_NOW =k_M* I_NOW, wobei k_M eine motorspezifische Drehmomentkonstante ist.

According to one embodiment, the determination of the actual torque M _NOW includes:

• measuring an actual excitation current I _NOW of the motor in a loaded condition; Calculating the actual torque M _NOW taking into account the measured actual excitation current I _NOW according to a motor-specific relation M _NOW =k _M * I _NOW , where k _M is a motor-specific torque constant.

As a result, the technical advantage can be achieved that a precise determination of the actual torque M _NOW can be achieved. For this purpose, measured values of the actual excitation current I _NOW of the motor are recorded in a loaded state. Based on the measured values of the actual excitation current I _NOW , the actual torque M _NOW is then calculated according to the motor-specific relation M=k _M *I between the torque M and the excitation current I. This enables the actual actual torque M _NOW of the motor operated under load to be precisely determined without an actual measurement of the torque M having to be carried out for this purpose. The technically much simpler measurement of the actual excitation current I _NOW enables a simplified determination of the torque M.

• Messen einer Ist-Erregerspannung U_NOW des Motors in einem unbelasteten Zustand;
• Berechnen eines verketteten magnetischen Flusses ψ des unbelasteten Motors unter Berücksichtigung der gemessenen Ist-Erregerspannung U_NOW;
• Berechnen einer motorspezifischen Flusskonstante k_Ψ gemäß einer Relation ψ =k_Ψ *I;
• Berechnen einer motorspezifischen Drehmomentkonstante gemäß einer Relation k_M=k_ψ *p, wobei p eine Polpaar des elektronisch kommutierten Motors ist.

According to one embodiment, the method further comprises:

• measuring an actual excitation voltage U _NOW of the motor in an unloaded state;
• Calculating a phase-to-phase magnetic flux ψ of the unloaded motor, taking into account the measured actual excitation voltage U _NOW ;
• calculating a motor-specific flux constant _kΨ according to a relation ψ= _kΨ *I;
• Calculating a motor-specific torque constant according to a relation k _M =k _ψ *p, where p is a pair of poles of the electronically commutated motor.

In this way, the technical advantage can be achieved that a simple and precise determination of the motor-specific torque constant k _M and associated simple and precise determination of the torque based on measured values of the excitation current according to the motor-specific relation M = k _M * I between the torque M and the Excitation current I is enabled. For this purpose, an actual excitation voltage U _NOW of the motor is first measured in an unloaded state and a phase-to-phase magnetic flux ψ is calculated based on the measured values of the actual excitation voltage U _NOW . Based on the interlinked magnetic flux ψ, a motor-specific flux constant k _Ψ according to a motor-specific relation Ψ = k _Ψ *I between the interlinked magnetic flux ψ and the excitation current are calculated. Based on the motor-specific flux constant k _Ψ , the motor-specific torque constant k _M can then be calculated according to the relation k _M =k _ψ *p, where p is a pole pair of the electronically commutated motor. A simple measurement of the actual excitation voltage U _NOW and the motor-specific relationships can be used to calculate the motor-specific torque constant k _M , which is used for determining the torque based on the values of the excitation currents I shown above.

The motor-specific torque constant k _M and the motor-specific flux constant k _Ψ are specific constants for each motor and explicitly depend on the actual design of the respective motor. However, the constants are independent of the actual values of the excitation current I or the excitation voltage U.

According to one embodiment, the actual excitation current I _NOW , the target excitation current I _NEW , the actual torque M _IST , the target torque M _NEW , the actual torque ripple W _NOW , the target torque ripple W _NEW , the motor-specific torque constant k _M , the motor-specific flux constant k _Ψ determined as a function of a rotor position of a rotor of the motor for a plurality of different rotor positions.

In this way, the technical advantage can be achieved that a simple determination of the setpoint torque and, associated therewith, of the setpoint torque ripple can be achieved. Thus, the above measurements and calculations are performed for individual rotor positions. The individual variables actual excitation current I _NOW , target excitation current I _NEW , actual torque M _NOW , target torque M _NEW , actual torque ripple W _NOW , target torque ripple W _NEW , motor-specific torque constant k _M , motor-specific flux constant k _ψ , actual -Excitation voltage U _NOW are variable quantities and depend directly on the rotor position of the rotor relative to a stator of the motor. By carrying out the measurements and calculations of the individual variables described above for different rotor positions, the calculation and the relationships used can be substantially simplified and the entire method can therefore be accelerated. This enables the desired setpoint torque ripple W _NEW and the corresponding setpoint excitation current I _NEW to be determined easily, precisely and quickly.

According to one embodiment, the motor is a polyphase motor, wherein measuring the excitation current comprises measuring phase excitation currents of the individual motor phases, and wherein the excitation current is a superposition of the multiple phase excitation currents of the motor phases.

In this way, the technical advantage can be achieved that a broad applicability of the method according to the invention is made possible by the method being able to be applied to any electronically commutated motors with a plurality of excitation phases.

According to one embodiment, a target phase excitation current results from a sum of an actual phase excitation current and a difference between the actual excitation current I _NOW and the target excitation current I _NEW divided by the number of phases.

As a result, the technical advantage can be achieved that a simplified determination of the desired setpoint torque M _NEW and the desired setpoint torque ripple W _NEW for multi-phase motors is achieved. For this purpose, the setpoint phase excitation currents I _{NEW_PH} of the individual motor phases are determined using an actually measured actual phase excitation current I _{NOW_PH} and a difference _Σn I- _NEW between the actual excitation current I _NOW and the setpoint excitation current I _NEW . The actual excitation current I _NOW and the setpoint excitation current I _NEW each describe a loop current that describes the complete current loop of the motor that includes the individual motor phases and results from a sum of the individual phase currents. As a result, the determination of the individual setpoint phase currents I _{NEW_PH can be} simplified and the method according to the invention can be made less complex and thereby accelerated.

According to a second aspect of the invention, an electronically commutated motor is provided, the motor having a torque ripple optimized according to the method according to one of the preceding embodiments.

As a result, the technical advantage can be achieved that an electronically commutated motor can be provided with improved torque ripple and, associated therewith, with improved noise vibration harshness.

According to a third aspect, a computer program product is provided, comprising instructions which, when the program is executed by a computer, cause the latter to execute the method according to one of the preceding embodiments.

• 1 eine schematische Darstellung eines elektronisch kommutierten Motors gemäß einer Ausführungsform;
• 2 ein Flussdiagramm eines Verfahrens zur Optimierung eines Betriebs eines elektronisch kommutierten Motors gemäß einer Ausführungsform;
• 3 ein weiteres Flussdiagramm des Verfahrens zur Optimierung eines Betriebs eines elektronisch kommutierten Motors gemäß einer weiteren Ausführungsform;
• 4 eine schematische Darstellung eines Drehmoments mit einer Drehmomentwelligkeit eines elektronisch kommutierten Motors; und
• 5 eine schematische Darstellung eines Computerprogrammprodukts.

Exemplary embodiments of the invention are explained with reference to the following drawings. In the schematic drawings show:

• 1 a schematic representation of an electronically commutated motor according to an embodiment;
• 2 a flow chart of a method for optimizing an operation of an electronically commutated motor according to an embodiment;
• 3 a further flowchart of the method for optimizing an operation of an electronically commutated motor according to a further embodiment;
• 4 a schematic representation of a torque with a torque ripple of an electronically commutated motor; and
• 5 a schematic representation of a computer program product.

1 12 shows a schematic representation of an electronically commutated motor 200 according to an embodiment.

1 shows an electronic commutated motor 200 with a stator 203 and a rotor 201 arranged to be rotatable relative to the stator 203. In the embodiment shown, the motor 200 is designed as a polyphase motor and comprises three excitation coils 205, each of which forms a motor phase U, V, W, and which are each arranged in a delta connection. Alternatively, the motor 200 may have any number of different phases arranged in any arrangement with respect to one another. The motor 200 is controlled via a motor controller 207, which includes a processor, for example. For example, a setpoint excitation current I _NEW determined using method 100 can be stored in motor controller 207, via which optimized operation of motor 200 with minimized noise development of motor 200 is made possible.

The individual motor phases U, V; W are each energized by means of an actual phase excitation current I _{NOW_PH} , whereupon the individual phases U, V, W generate a corresponding magnetic flux density for driving the rotor 201 . For this purpose, the individual excitation coils 205 are supplied with a corresponding actual phase excitation voltage U _{NOW_PH} . The actual phase excitation current I _{NOW_PH} and the actual phase excitation voltage U _{NOW_PH} can be identical for each phase U,V,W. Alternatively, the actual phase excitation current I _{NOW_PH} and the actual phase excitation voltage U _{NOW_PH} can be individually different for each phase. The rotor 201 can be rotated by an angle of rotation α with respect to a preferred direction 209 of the stator 203 . In 1 this is shown via the angle α between the preferred direction 209 of the stator 203 and a rotor axis 211 of the rotor 201. The motor 200 can be controlled with a corresponding excitation voltage U via the motor controller 209 via the line 213 .

2 10 shows a flow diagram of a method 100 for optimizing an operation of an electronically commutated motor 200 according to an embodiment.

The method 100 according to the invention for optimizing an operation of an electronically commutated motor 200 is applicable to a motor 200 according to in 1 embodiment shown applicable.

In order to optimize the operation of the motor 200, an actual torque M _NOW with an actual torque ripple W _NOW of the motor 200 is first determined in a method step 101 in a loaded state.

The torque ripple W describes variations in the torque M as a function of the angle of rotation α or the rotor position of the rotor 201 relative to the stator 203. The torque ripple results from a maximum value of the torque MMAX and a minimum value of the torque MMIN according to the following relationship: W=( M _max -M _min )/((M _max +M _min )/2). The relation shown is valid both for the actual torque M _NOW and the actual torque ripple W _NOW and for the setpoint torque M _NEW and the setpoint torque ripple W _NEW .

After the actual torque M _NOW and the actual torque ripple W _{NOW have} been determined, a setpoint torque M _NEw with a setpoint torque ripple W _NEW of the loaded motor 200 is determined in a further method step 103 . In this case, the setpoint torque ripple W _NEW is smaller than the previously determined actual torque ripple W _NOW .

A corresponding target excitation current I _NEW is then determined in a method step 105, which is suitable for driving motor 200 in the loaded state via the specified target excitation current I _NEW to produce the desired target torque M _NOW with the desired target torque ripple W generate _NOW .

3 FIG. 1 shows a further flow diagram of the method 100 for optimizing an operation of an electronically commutated motor 200 according to a further embodiment.

In the 3 The embodiment of the method 100 shown is based on the 2 shown embodiment and includes all method steps described there. If these remain unchanged in the following embodiment, is of apart from a renewed detailed description.

Deviating from the embodiment in 2 In the embodiment shown, method 100 includes a method step 123. In method step 123, an actual excitation voltage U _NOW of motor 200 is measured in an unloaded state by recording corresponding measured values from a voltmeter.

In a subsequent method step 125, based on the measured values of the actual excitation voltage U _NOW , a phase-to-phase magnetic flux Ψ is generated in accordance with the relationships between the excitation voltage U and the phase-to-phase magnetic flux Ψ known from the prior art and the motor-specific parameters of motor 200, in particular of the individual motor phases U, V, W, calculated.

Based on the calculated phase-to-phase magnetic flux Ψ, a motor-specific flux constant K _Ψ is calculated in a subsequent method step 127 using a relationship known from the prior art between the phase-to-phase magnetic flux Ψ and the excitation current I Ψ _NOW =k _Ψ *I _NOW .

The motor-specific flux constant k _Ψ is a constant individually adapted for each motor 200, and in particular for the respective motor phases U, V, W and the individual performance parameters of the phases, which is independent of the actual magnitude of the excitation current I or the interlinked magnetic flux Ψ is.

In a subsequent method step 129, a motor-specific torque constant k _M is calculated based on the calculated motor-specific flux constant K _Ψ according to a relation between the motor-specific flux constant k _Ψ and the motor-specific torque constant k _M according to k _M =k _Ψ *p known from the prior art. P represents a pair of poles of the stator-rotor arrangement.

The motor-specific torque constant k _M is analogous to the motor-specific flux constant k _Ψ a constant dependent on the individual performance parameters of the motor 200, in particular the individual phases U, V, W, by means of which a relation between the torque M and the excitation current I according to M= _KM *I can be calculated.

After the motor-specific torque constant k _M has been determined, the actual torque M _NOW is determined in method step 101 . In the embodiment shown, the actual excitation current I _NOW of the motor 200 in the loaded state is first measured in a method step 119 by recording corresponding measured current values of an ammeter.

Subsequently, in a method step 121, based on the measured values of the actual excitation current I _NOW of the loaded motor 200, taking into account the previously calculated motor-specific torque constant k _M and the stated motor-specific relationship between the torque M and the excitation current I, M _NOW =k _M * I _Now das Actual torque M _NOW of engine 200 under load is calculated. At the same time, an actual torque ripple W _NOW is calculated according to the above-mentioned relation for the torque ripple W based on the calculated values for the actual torque M _NOW .

Taking into account the calculated actual torque M _NOW and the calculated corresponding actual torque ripple W _NOW , a target torque M _NEW with a corresponding target torque ripple W _NEW is then determined in method step 103, which in particular has a lower value than the previously calculated actual -Torque ripple W _NOW . Here, the target torque M _NEW and the target torque ripple W _NEW represent ideal values of the torque M and the torque ripple W of the motor 200 in the loaded state, which should be achieved for optimal operation. The target values of the torque M and the torque ripple W are used in the present method 100 as target values that are to be achieved via execution of the method 100 .

After the setpoint torque M _NEW and the setpoint torque ripple W _{NEW have} been determined, a corresponding setpoint excitation current I _NEW is determined in method step 105 . For this purpose, method step 105 includes a method step 117, in which the target excitation current I _NEW taking into account the target torque M _NEW and the motor-specific torque constant k _M according to the motor-specific relationship between torque M and excitation current I, M _NEW =K _M *L _NEW is calculated. The setpoint excitation current I _NEW here represents a setpoint value of the excitation current I, which leads to the desired setpoint torque M _NEW in the motor 200 in the loaded state without taking account of losses within the motor 200 . In this case, the setpoint excitation current I _NEW can deviate from the actual actual excitation current I _NOW , which flows when the motor 200 is driven in the loaded state.

After the setpoint excitation current I _NEW has been calculated, in a further method step 107 the motor 200 is controlled in the loaded state in accordance with the calculated setpoint excitation current I _NEW .

The activation of the motor 200 according to the calculated setpoint excitation current I _NEW can include, for example, the application of a setpoint excitation voltage U _NEW corresponding to the setpoint excitation current I _NEW to the individual excitation coils 205 of the motor phases U, V, W.

Then, in a method step 109, the actual excitation current I _NOW actually flowing in the loaded state in the motor 200 driven according to the calculated target excitation current I _NEW is determined by recording corresponding measured current values of an ammeter.

After measuring the actually flowing actual excitation current I _NOW in method step 109, in a further method step 111 based on the actually measured actual excitation current I _NOW a corresponding actual torque M _NOW with a corresponding actual torque ripple W _NOW taking into account the motor-specific torque constant k _M and the motor-specific relation between torque M and excitation current I, M _NOW =K _M *I _NOW , and according to the above relation to determine torque ripple based on the maximum and minimum values of torque Mmax, Mmin according to the relation W=(M _max -M _min )/((M _max +M _min )/2), whereby the actual values of the torques are to be used in the relation.

After calculating the actually present actual torque M _NOW and the corresponding actual torque ripple W _NOW , which are present in motor 200 in the loaded state when it is controlled according to the previously calculated target excitation current I _NEW , these are Target torque M _NEw and the associated target torque ripple W _NEW compared in a method step 111. Due to real losses within motor 200, actual torque M _NOW and associated actual torque ripple W _NOW can deviate from the desired ideal values of calculated setpoint torque M _NEW and associated setpoint torque ripple W _NEW .

If, in method step 111, when comparing the actual torque ripple W _NOW with the desired target torque ripple W _NEW , a difference between the two torque ripple values that exceeds a previously determined limit value is determined, then method 100 becomes recursive in one method step with the renewed execution of method step 103 115 continued.

For this purpose, based on the actually present actual torque M _NOW and the associated actual torque ripple W _NOW , a new target torque M _NEW with a corresponding target torque ripple W _NEW is determined, which in turn is smaller than the actual torque ripple W _NOW . A corresponding setpoint excitation current I _NEW is then calculated, and motor 200 is driven in accordance with the calculated new setpoint excitation current I _NEW . The actual excitation current I _NOW that is actually present is then determined in turn by means of corresponding current measurements, and the actual torque M _NOW that is actually present and the associated actual torque ripple W _NOW are calculated based thereon. If a deviation between the actual torque ripple W _NOW and the newly determined target torque ripple W _NEW is also determined, the method is continued iteratively according to the sequence described above until a difference between the two torque ripple values reaches or falls below the previously determined limit value.

When the previously determined limit value is reached or fallen below, method 100 is ended and the target excitation current I _NEW calculated according to the target torque M _NEW and the associated target torque ripple W _NEW serves as the optimum control value for the motor 200 in the loaded state operation of the motor 200 with minimal noise development and optimal noise-vibration-harshness performance. The setpoint excitation current I _NEW determined in accordance with the method 100 can be stored, for example, in the motor controller 207, so that the motor 200 can be controlled optimally and with minimized noise development in the future according to the stored setpoint excitation current I _NEW .

In the relations shown above, the excitation current I corresponds to a loop current that exceeds the current over the complete conductor loop of the in 1 shown delta connection of the individual motor phases U, V, W corresponds to the current flowing. With a plurality of different motor phases, with a phase current I_ _PH flowing in each motor phase, the loop current I corresponds to a sum of the individual phase excitation currents I_ _PH , I _NOW =Σ _n I _{NOW_PH} , I _NEW =Σ _n I _{NEW_PH} , where n is the Number of motor phases is.

In order to measure the actually present actual excitation current I _NOW , each individual actual phase excitation current I _{NOW_PH of} each individual motor phase U, V, W is measured in a motor 200 with a plurality of motor phases U, V, W. Based on the measured actual phase excitation currents I _{NOW_PH} , the respective target phase excitation currents I _{NEW_PH} are calculated according to the following relation I _{NEW_PH} =I _{Now_PH} +ΔI _{NEW_PH} .

The difference ΔI _{NEW_PH} corresponds to the difference I _{NEW_PH} -I _{NOW_PH} .

For simplification, this difference ΔI _{NEW_PH} can be determined from the difference in the loop current ΔI _NEW = I _NOW - I _NEW according to the following relation ΔI _{NEW_PH} = ΔI _NEW / n , where n is the number of motor phases. In the case of a motor 200 with a number n of different motor phases, the method described above can thus be simplified by using only the loop current I as the sum of the individual phase currents I _{_PH} according to I _Now =Σ _n I _{Now_PH} , I _NEW =Σ _n I _NEW _ _PH for the calculations is used. To calculate the individual setpoint phase currents I _{NEW_PH} , the difference ΔI _NEW in the loop current I is used, and the identical phase difference ΔI _{NEW_PH is} taken into account for each phase U, V, W.

The method 100 presented above is further simplified in that the calculations shown above are each carried out for individual rotor positions of the rotor 201 relative to the stator 200 . All of the above quantities are variable and depend directly on the rotor position or the angle of rotation α M _Now (α), M _NEW (α), I _NOW (α), I _NEW (α), I _{NOVV_PH} (α), I _{NEW_PH} (α), ΔI _NEW (α), ΔI _{NEW_PH} (α), U _NOW (α), U _NEW (α), U _{NOW_PH} (α), U _{NEW_PH} (α) , W _NOW (α), W _NEW ( α), Ψ _NOW (α) Ψ _NEW (α), k _M (α), K _ψ (α).

A significant simplification of the equations used can be achieved by calculating the individual variables according to the above-mentioned relations for fixed angles of rotation α. For a complete description of the torque M or the torque ripple W, the method 100 mentioned above can thus be carried out for different values of the angle of rotation α between 0° and 360°. Depending on the desired accuracy, the setpoint torque M _NEW , the setpoint torque ripple W _NEW and the setpoint excitation current I _NEW associated therewith can be determined for different increments, for example every 5° or every 0.5°. Due to the periodic course of the torque M or the torque ripple W, the method 100 can also be carried out exclusively for a partial range of the angle of rotation α between 0° and 360°. Due to the periodic curve, a setpoint excitation current I _NEW can nevertheless be determined for a complete angular range between 0° and 360°, so that the motor can be operated with the desired torque ripple W _NEW according to the determined setpoint excitation current I _NEW .

The method 100 described can be carried out at the factory directly after the engine 200 has been manufactured in order to determine an optimal operating state for later use. Alternatively, the method 100 can be carried out during operation of the engine 200 that has already been installed. For example, during an adjustment process in which an optimal operating condition is to be found.

4 shows a schematic representation of a torque with a torque ripple of an electronically commutated motor 200.

4 shows a graphical representation of an angle dependency of an actual torque M _NOW and a setpoint torque M _NEW . In this case, the actual torque M _NOW has an increased torque ripple, which is reflected in the large difference between the maximum value Mmax of the actual torque M _NOW and the minimum value M _min of the actual torque M _NOW . The desired setpoint torque M _NEW , on the other hand, has a significantly lower torque ripple W _NEW , which is represented by the significantly smaller difference between the maximum values M _max and the minimum values M _min of the setpoint torque M _NEW .

The representation shown is only an example and does not represent a real course of the torque of an electronically commutated motor 200 and is not intended to limit the present invention.

5 shows a schematic representation of a computer program product 300.

In 5 the computer program product 300 is stored on a commercially available storage medium 301, for example a hard drive or another data medium.

Claims (10)

Method (100) for optimizing an operation of an electronically commutated motor (200), comprising: determining (101) an actual torque M _NOW with an actual torque ripple W _NOW of the motor (200) in a loaded state; Determining (103) a target torque M _NEw with a target torque ripple W _NEW of the loaded motor (200), the target torque ripple W _NEW being smaller than the actual torque ripple W _NOW ; Determining (105) a target excitation current I _NEW , the target excitation current I _NEW causing the target torque M _NEW with the target torque ripple W _NEW in the loaded motor (200). Method (100) according to claim 1 , further comprising: driving (107) the motor (200) with the target excitation current I _NEW ; Measuring (109) a further actual excitation current I _NOW of the motor (200) driven with the target excitation current I _NEW determined in step (105); Calculating (111) a further actual torque M _NOW with a further actual torque ripple W _NOW taking into account the measured further actual excitation current I _NOW according to a motor-specific relation M _NOW =k _M * I _NEW , where k _M is a motor-specific torque constant; Comparing (113) the setpoint torque ripple W _NEW with the further actual torque ripple W _NOW ; and iteratively (115) performing the steps (103, 105, 107, 109, 111, 113) if a difference between the desired torque ripple W _NEW and the further actual torque ripple W _NOW exceeds a predetermined limit. Method (100) according to one of the preceding claims, wherein the determination (105) of the target excitation current I _NEW comprises: calculating (117) the target excitation current I _NEW taking into account the target torque M _NEW according to a motor-specific relation M _NEW =k _M * I _NEW , where k _M is a motor-specific torque constant. Method (100) according to one of the preceding claims, wherein the determination (101) of the actual torque M _NOW comprises: measuring (119) an actual excitation current I _NOW of the motor (200) in a loaded state; Calculating (121) the actual torque M _NOW taking into account the measured actual excitation current I _NOW according to a motor-specific relation M _NOW =k _M * I _NOW , where k _M is a motor-specific torque constant. Method (100) according to one of the preceding claims, further comprising: measuring (123) an actual excitation voltage U _NOW of the motor (200) in an unloaded state; Calculating (125) a phase-to-phase magnetic flux Ψ of the unloaded motor (200) taking into account the measured actual excitation voltage UNOW; calculating (127) a motor-specific flux constant _kΨ according to a relation ψ= _kΨ *I; Calculating (129) a motor-specific torque constant according to a relation k _M =k _ψ *p, where p is a pole pair of the electronically commutated motor (200). Method (100) according to one of the preceding claims, wherein the actual excitation current I _NOW , the target excitation current I _NEW , the actual torque M _IST , the target torque M _NEW , the actual torque ripple W _NOW , the target torque ripple W _NEW , the motor-specific torque constant k _M , the motor-specific flux constant k _Ψ as a function of a rotor position of a rotor (201) of the motor (200) for a plurality of different rotor positions. Method (100) according to any one of the preceding claims, wherein the motor (200) is a multi-phase motor (200), wherein the measuring of the excitation current comprises measuring phase excitation currents of the individual motor phases, and wherein the excitation current is a superposition of the plurality of phase excitation currents of the motor phases . Method (100) according to claim 7 , wherein a target phase excitation current I _{NEW_ph} results from a sum of an actual phase excitation current I _{NOW_ph} and a difference between the actual excitation current I _NOW and the target excitation current I _NEW divided by the number of phases. Electronically commutated motor (200), with a according to the method (100) according to any one of the preceding Claims 1 until 8th optimized torque ripple. Computer program product (300), comprising instructions which, when the program is executed by a computer, cause the latter to carry out the method (100) according to one of the preceding ones Claims 1 until 8th to execute.

Images