阅读说明：本技术 用于确定同步电机的转子的方位角的方法和设备 (Method and device for determining the azimuth angle of the rotor of a synchronous machine ) 是由 A.马斯 G.埃斯特格拉尔 于 2018-04-25 设计创作，主要内容包括：本发明涉及一种用于确定同步电机(1)的转子(2)的方位角的方法和设备。该设备构造得具有：电压生成装置(12),用于在转子(2)静止时在定子固定的坐标系中的角度产生电压脉冲；测量装置(14),用于测量相应的、源于通过电压生成装置(12)产生的电压脉冲的电流值；和计算装置(16),该计算装置被设立为：存储所测量的电流值的电流信号波形；产生无平均值的电流信号波形,其方式是移动该电流信号波形或所测量的电流值；计算无平均值的电流信号波形的积分函数(83)；而且基于所计算出的积分函数(83)来确定转子(2)的方位角。(The invention relates to a method and a device for determining the azimuth angle of a rotor (2) of a synchronous machine (1). The apparatus is configured to have: voltage generating means (12) for generating voltage pulses at an angle in a coordinate system in which the stator is fixed when the rotor (2) is stationary; measuring means (14) for measuring the respective current values resulting from the voltage pulses generated by the voltage generating means (12); and a computing device (16) set up to: storing a current signal waveform of the measured current value; generating a current signal waveform without an average value by shifting the current signal waveform or the measured current value; calculating an integral function (83) of the current signal waveform without the mean value; and determining the azimuth angle of the rotor (2) based on the calculated integral function (83).)

1. A method for determining an azimuth angle of a rotor (2) of a synchronous machine (1), the method having the steps of:

generating (S10) at least one voltage pulse each at a predetermined electrical angle in a coordinate system fixed in relation to the stator of the stator (3) of the synchronous machine (1) while the rotor (2) of the synchronous machine (1) is stationary;

measuring (S20) each at least one respective current value resulting from the generated voltage pulse;

storing (S30) a current signal waveform of the measured current value;

generating (S40) a current signal waveform without an average value by shifting the stored current signal waveform or the measured current value;

calculating (S50) an integral function (83) of the current signal waveform without the mean value; and also

Determining (S60) an azimuth angle of the rotor (2) based on the calculated integral function (83).

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

wherein for each predetermined angle a corresponding electrical angle increased by 180 ° is also predetermined; and also

Wherein the current signal waveform of the measured current value is stored only as a function of the angle within one half of 360 °, wherein the value for each predetermined electrical angle within the one half of 360 ° is determined not only as a function of at least one current value measured for the predetermined electrical angle but also as a function of at least one current value measured for the predetermined electrical angle shifted by 180 °.

3. The method according to any one of claims 1 or 2,

wherein the determination (S60) of the azimuth angle of the rotor (2) comprises the steps of:

determining an average (84) of the calculated integration functions (83); and also

Determining a first angle value (85) at which the calculated integral function (83) intersects the determined average value (84) of the calculated integral function (83);

wherein an azimuth angle of the rotor (2) is determined (S60) based on the determined first angle value (85).

4. The method of claim 3, wherein the first and second light sources are selected from the group consisting of,

wherein an angle value at which the calculated integral function (83) intersects the determined average value (84) of the calculated integral function (83) during a rise of the calculated integral function (83) from a low value towards a higher value is determined as the first angle value (85).

5. The method of claim 4, wherein the first and second light sources are selected from the group consisting of,

wherein additionally a second angle value is determined at which the calculated integral function (83) intersects the determined average value (84) of the calculated integral function (83) during a fall of the calculated integral function (83) from a higher value towards a lower value; and also

Wherein an azimuth angle of the rotor (2) is determined (S60) additionally based on the determined second angle value (86).

6. The method according to any one of claims 3 to 5,

wherein the sum and/or average of the current values measured at the first angle value (85) is compared with the sum and/or average of the current values measured at a third angle value, which is equal to the determined first angle value (85) plus 180 °, and wherein the angle value for which the sum and/or average of the measured current values is larger is determined from the first angle value (85) and the second angle value as the azimuth angle of the rotor (2).

7. The method according to any one of claims 3 to 5,

wherein the determination (S60) of the azimuth angle of the rotor (2) further comprises the steps of:

electrically generating a first electrical saturation pulse at the determined first angle value (85);

measuring a first current value, the first current value being derived from the first electrical saturation pulse;

electrically generating a second electrical saturation pulse at a third angle value equal to the determined first angle value (85) plus 180 °;

measuring a second current value, the second current value being derived from the second electrical saturation pulse;

determining the first angle value as the azimuth angle of the rotor (2) if the first current value is greater than the second current value, and determining the third angle value as the azimuth angle of the rotor (2) if the second current value is greater than the first current value.

8. The method of any one of claims 1 to 7,

wherein a plurality of voltage pulses are generated at each of the predetermined electrical angles and the current values respectively resulting therefrom are measured; and wherein the current signal waveform is stored based on all measured current values.

9. The method of any one of claims 1 to 8,

wherein the current values of the stored current signal waveforms are each given by an average or a sum of all current values determined for the respective predetermined electrical angle.

10. The method of any one of claims 1 to 9,

wherein a pulse in the opposite direction is generated after each voltage pulse,

and/or after each generated voltage pulse decays and/or after measuring (S20) the corresponding current value, waiting a predetermined period of time before generating the next voltage pulse;

wherein the predetermined period of time is between 1 microsecond and 500 microseconds.

11. An apparatus (10) for determining an azimuth angle of a rotor (2) of a synchronous machine (1), the apparatus having:

a voltage generating device (12) which is set up to generate (S10) at least one voltage pulse in each case at a predetermined electrical angle in a stator-fixed coordinate system with respect to a stator (3) of the synchronous machine (1) when a rotor (2) of the synchronous machine (1) is stationary;

measuring devices (14) which are set up to measure (S20) in each case at least one respective current value which is derived from the voltage pulse generated by the voltage generating device (12); and

a computing device (16) set up to:

-storing the current signal waveform of the measured current value;

-generating a current signal waveform without an average value by shifting the current signal waveform and/or the measured current value;

-calculating an integration function (83) of the current signal waveform without mean value; and also

-determining an azimuth angle of the rotor (2) based on the calculated integral function (83).

12. The device (10) according to claim 11,

wherein the voltage generating device (12) is designed such that, for each predetermined angle, a corresponding electrical angle increased by 180 ° is also predetermined; and also

Wherein the computing device (16) is set up to: storing the current signal waveform of the current value only as a function of an angle within one-half of 360 °, wherein the value for each predetermined electrical angle within the one-half of 360 ° is determined not only as a function of at least one current value measured for the predetermined electrical angle but also as a function of at least one current value measured for the predetermined electrical angle shifted by 180 °.

Technical Field

The invention relates to a method and a device for determining the azimuth angle of a rotor of a synchronous machine, in particular a permanent magnet synchronous machine, preferably a motor of a vehicle, which is designed as a permanent magnet synchronous machine. The vehicle may be a partially electric-driven vehicle (hybrid vehicle) or may be a purely electric-driven vehicle (electric vehicle).

Background

Synchronous machines are alternating-current machines in which a rotor, also referred to as Läufer, runs in synchronism with a rotating magnetic field of a stator, also referred to as Ständer, the rotating magnetic field of the stator is generated and rotated by generating a current and a voltage at periodically varying electrical angles.

In order to be able to generate a directional torque in the case of synchronous machines, the orientation of the rotor relative to the stator, that is to say the so-called azimuth angle of the rotor or the rotor azimuth angle, must be known precisely. In this case, the mechanical orientation of the rotor relative to the stator that can be seen from the outside is not important, but rather the electromagnetically active orientation that differs from this mechanical orientation due to the number of pole pairs present in each case and due to component tolerances in the rotor and the stator. More precisely, the electrical angle between the rotor magnetic field and the stator magnetic field is important. In the following, all angle parameters refer to electrical angles only.

DE 102008042360 a1 describes the determination of the rotor angle of a synchronous machine at standstill, in which voltage pulses with different electrical angles are applied to the synchronous machine.

In determining the rotor azimuth, a 180 ° ambiguity may occur. It is to be understood that: the rotor azimuth angle can only be determined precisely up to 180 ° in the first place, i.e., for example, a distinction cannot be made between a rotor azimuth angle of 7 ° and a rotor azimuth angle of 187 °.

In scientific publications

M, Schroedel "sensory control of AC machines at low speed and having been carried out on the" IN FORM "method", Industry Applications Conference, 1996, 31 th annual IAS Conference, Conference Record of the 1996 IEEE (Conference Record of IEEE 1996), 1996, volume 1, page 270-,

and

holtz "Initial Rotor policy Detection and sensory Control of PM Synchronous Machines", Industry Applications Conference, 2006, 41 th annual IAS, Conference Record of the 2006 IEEE, 2006, 4, 2040-,

methods are described that can resolve 180 ° ambiguities that may occur with the use of saturation pulses.

Disclosure of Invention

The invention discloses a method with the features of patent claim 1 and an apparatus with the features of patent claim 11.

Accordingly, a method for determining an azimuth angle of a rotor of a synchronous machine is provided, having the steps of: generating voltage pulses at or at a predetermined electrical angle in a coordinate system fixed in relation to a stator of the synchronous machine, while a rotor of the synchronous machine is stationary; measuring a corresponding current value resulting from the generated voltage pulse; storing a current signal waveform of the measured current value; generating a current signal waveform without an average value by shifting the stored current signal waveform and/or the measured current value; calculating an integral function of the current signal waveform without the average value; and determining the azimuth angle of the rotor based on an integral function of the calculated current signal waveform without the average value.

In particular, within the scope of the present invention, the meaning of the term "based on" should be interpreted correspondingly to the meaning of the term "according to". In particular, within the scope of the present invention, the meaning of the term "originating from something" should be interpreted correspondingly to the meaning of the term "caused by something".

Generating the voltage pulse at the predetermined electrical angle includes: voltage pulses are generated and applied to a stator winding of a stator of the synchronous machine, such that a stator magnetic field is generated in an angular direction in the direction of a predetermined electrical angle on the basis thereof.

A current value measured for a predetermined electrical angle is to be understood as a current value which is derived from a voltage pulse generated at the predetermined electrical angle.

A current signal waveform without an average value is to be understood as a current signal waveform with an average value of zero.

In order to be able to achieve an exact determination of the azimuth angle of the rotor, the voltage pulses are preferably generated such that the rotor is not in rotation, that is to say is not rotating, as a result of these voltage pulses. The correspondingly limited possible height of the voltage pulses generally deteriorates the signal-to-noise ratio, which is however at least compensated for by the method steps described at present.

Preferably, for each predetermined angle, a corresponding electrical angle increased by 180 ° is also predetermined (i.e. for example for an electrical angle of 7 °, an electrical angle of 187 ° is also predetermined). In this case, it is particularly preferred to store the current signal waveform of the current value only as a function of an angle within one half of 360 ° (that is to say, for example, as a function), wherein the value for each predetermined electrical angle within the one half of 360 ° is determined not only from at least one current value measured for this predetermined electrical angle but also from at least one current value measured for the predetermined electrical angle shifted by 180 °. In other words, the current value measured for an electrical angle within the other half of 360 ° may be assigned or in other words to an electrical angle within the one half of 360 °, wherein it may not be taken into account for the storage of the current signal waveform whether the determined measured current value is initially from the one half of 360 ° or from the other half of 360 °.

The angle of this half of 360 ° may for example be between 0 ° and <180 °, such that the other half of 360 ° extends from 180 ° to <360 °. Thus, each of the current values measured for a predetermined electrical angle of, for example, 183 ° (within the other half) may be assigned to an electrical angle of 3 ° within the half, so that a current signal waveform for an electrical angle of 3 ° is correspondingly generated or stored in values based not only on one or more current values measured for 3 ° but also on one or more current values measured for 183 °.

Within the scope of the present invention, the meaning of the term "based on" should be interpreted correspondingly to the meaning of the term "according to".

Thus, depending on whether a unique voltage pulse is generated for each electrical angle and the corresponding current value is measured or whether a plurality of voltage pulses are generated and/or a plurality of current values are measured, each value of the stored current signal waveform is advantageously based on two or more values for each predetermined angle within the half of 360 °, wherein the value for each predetermined angle can be generated in particular by averaging or summing all the measured current values assigned to this predetermined angle, that is to say for example for 3 °, by averaging or summing all the measured current values at 3 ° and at 183 °.

In particular, the current signal waveform can be stored only in accordance with a predetermined electrical angle, for example only in accordance with electrical angles at a distance of 3 ° (for example 0 °, 3 °, 6 °, … …). Thus, the current signal waveform may be constructed as a function having a discrete defined set. Alternatively, the current signal waveform may also be generated or stored with values for electrical angles lying between predetermined electrical angles, which may be generated by interpolation.

Alternatively to the values described above, it is easy to understand that: the half angle of 360 ° can also extend, for example, between 15 ° and <195 ° and the other half can extend from 195 ° to <15 °, i.e. the 360 ° can be set at any desired point to 2 equally large halves, wherein the current signal waveform has only one half of the two halves of 360 ° as a domain of definition.

Alternatively, the current signal waveform can also be stored on the basis of the current values measured for all predetermined electrical angles, that is to say without the electrical angle within one half having to be assigned to the electrical angle within the other half. The predetermined electrical angles may be arranged evenly distributed within 360 °.

There is also provided an apparatus for determining an azimuth angle of a rotor of a synchronous machine, the apparatus comprising: voltage generating means which are set up to generate voltage pulses at or at a predetermined electrical angle in a stator-fixed coordinate system with respect to a stator of the synchronous machine when the rotor of the synchronous machine is stationary; measuring means which are designed to measure the respective current values resulting from the voltage pulses generated by the voltage generating means; and a computing device, the computing device being configured to:

-storing the current signal waveform of the measured current value;

-generating a current signal waveform without an average value by shifting the current signal waveform and/or the measured current value;

-calculating an integral function of the current signal waveform without the mean value; and also

-determining the azimuth angle of the rotor based on the calculated integral function.

In a particularly preferred embodiment, the voltage generating device is designed such that for each predetermined angle, a corresponding electrical angle increased by 180 ° is also predetermined. In this embodiment, the computing device may be set up to: the current signal waveform of the current value is stored only as a function of the angle within one half of 360 ° (that is to say, for example, as a function), wherein the value of the current signal waveform for each predetermined electrical angle within the one half of 360 ° is determined not only as a function of at least one current value measured for the predetermined electrical angle but also as a function of at least one current value measured for the predetermined electrical angle shifted by 180 °.

THE ADVANTAGES OF THE PRESENT INVENTION

The methods described herein and the devices described herein can implement: the azimuth angle of the rotor of a synchronous machine, preferably a permanent magnet synchronous machine, is determined particularly precisely even in the case of large random measurement errors in the measurement of the current values. Since voltage generating devices, measuring devices and a computing device are generally required in any case for operating a synchronous machine, the device described herein deals with particularly few additional components or no additional components at all. The device can be integrated in particular into a synchronous machine.

Especially by using an integral function, the measurement error results in a much lower error in the determined rotor azimuth angle compared to methods based on derivative functions.

The invention is based on the detection of inductances in different electrical angular directions, which are not only predefined by the orientation of the stator windings, but also by the targeted interrogation of the inductances in arbitrary angular positions, wherein arbitrary angular positions can be interrogated by a suitable combination of at least two stator windings. In other words, by the targeted application of a voltage to two or more stator windings, voltage pulses can be generated at a predetermined electrical angle. In principle, an external magnetic field (due to the stator, caused by the generated voltage pulses) is applied in a certain angular direction (that is to say in a predetermined electrical angle), and the resulting current (lagging with respect thereto) is detected, which behaves in terms of u (t) = L. (di/dt). The angle-dependent effective magnetic permeability of the rotor is obtained by the material of the rotor, in particular by the combination of different materials of different magnetic permeability, and in particular by the rotationally asymmetrical shaping of the rotor.

Advantageous embodiments and developments emerge from the dependent claims and from the description with reference to the figures.

According to a preferred embodiment, the determination of the azimuth angle of the rotor comprises the following steps: determining an average of the calculated integration functions; and determining a first angle value at which the calculated integral function intersects the determined average value of the calculated integral function; wherein an azimuth angle of the rotor is determined based on the determined first angle value. Thus, the extremum of the stored current signal waveform can be determined simply and accurately and used to determine the rotor azimuth angle.

According to a particularly preferred embodiment, the angle value at which the calculated integral function intersects the determined mean value of the calculated integral function during the rise of the calculated integral function from the low value to the higher value is determined as the first angle value. In this way, the maximum value of the stored and mean-free current signal waveform, which represents the D-axis or D' -axis of the rotor in the rotor-fixed coordinate system, can be determined simply and accurately. Both the D-axis and the D' axis are rotor-fixed; the D-axis points in the direction of the azimuth angle of the rotor, the D' axis being arranged rotated 180 ° with respect to the D-axis.

According to a further preferred refinement, a second angle value is additionally determined at which the calculated integral function intersects the determined mean value of the calculated integral function during a fall of the calculated integral function from a higher value to a lower value, wherein the azimuth angle of the rotor is additionally determined on the basis of the determined second angle value. In this way, the minimum value of the current signal waveform without the mean value can be determined simply and accurately and used for determining the rotor azimuth angle.

According to a further preferred embodiment, the sum and/or average of the measured current values for the first angle value is compared with the sum and/or average of the measured current values for a third angle value, which is equal to the determined first angle value plus 180 °. From the first angle value and the second angle value, the angle value for which the sum and/or average of the measured current values is greater is determined as the azimuth angle of the rotor. Thus, 180 ° ambiguities can be resolved in a particularly simple manner.

According to another preferred embodiment, the determination of the azimuth angle of the rotor further comprises the following steps: electrically generating a first electrical saturation pulse at the determined first angle value; measuring a first current value, the first current value being derived from the first electrical saturation pulse; electrically generating a second electrical saturation pulse at a third angle value equal to the determined first angle value plus 180 °; measuring a second current value, the second current value being derived from the second electrical saturation pulse; if the first current value is greater than the second current value, a first angle value is determined as the azimuth angle of the rotor, and if the second current value is greater than the first current value, a third angle value is determined as the azimuth angle of the rotor.

According to a further preferred embodiment, a plurality of voltage pulses are generated at each of the predetermined electrical angles and the current values respectively resulting therefrom are measured; and a current signal waveform is made based on all the measured current values. By this, the accuracy of determining the azimuth angle of the rotor can be improved.

According to a further preferred embodiment, the stored values of the current signal waveform are each given by the mean value or the sum of all current values assigned to the respective predetermined electrical angle (for example within the half of 360 °).

According to another preferred embodiment, the voltage pulses have a pulse height of between 1 volt and 10 volts. According to a further preferred embodiment, the voltage pulse has a pulse duration of between 1 microsecond and 1000 microseconds. In any case, the voltage pulses are generated such that the stationary rotor is not set into rotation, that is to say remains stationary, by the voltage pulses.

According to a further preferred embodiment, after each generated voltage pulse has decayed and/or after the corresponding current value has been measured, a predetermined time period is waited before the next voltage pulse is generated. The predetermined time period may be, for example, between 1 microsecond and 500 microseconds, and may be, for example, 100 microseconds.

Drawings

The invention will be further elucidated on the basis of an embodiment which is represented in a schematic drawing of the drawing. Wherein:

fig. 1 shows a schematic block diagram of an apparatus for determining an azimuth angle of a rotor of a synchronous machine according to an embodiment of the invention;

fig. 2 to 4 show schematic diagrams for explaining the working principle of the device in fig. 1; while

Fig. 5 shows a schematic flow chart for illustrating a method for determining an azimuth angle of a rotor of a synchronous machine according to another embodiment of the invention.

Throughout the drawings, identical or functionally identical elements and devices are provided with the same reference numerals, unless otherwise specified. Numbering of method steps is done for clarity and should be taken to mean a definite temporal order, especially as long as it is not otherwise stated. In particular, a plurality of method steps can also be carried out simultaneously.

Detailed Description

Fig. 1 shows a block diagram of an apparatus 10 for determining the azimuth angle of a rotor 2 of a permanent magnet synchronous machine 1 according to one embodiment of the invention. The device 10 may be integrated into the permanent magnet synchronous machine 1 or the permanent magnet synchronous machine 1 may be part of the device 10. Instead of a permanent magnet synchronous machine 1, the device 10 can also be set up to be applied to any synchronous machine 1.

The device 10 comprises a voltage generation means 12 which is designed or set up to: when the rotor 2 of the synchronous machine 1 is stationary, i.e. when the synchronous machine 1 is not operating, at least one voltage pulse is generated in a predetermined electrical angle or at a predetermined electrical angle in a stator-fixed coordinate system with respect to the stator 3 of the synchronous machine 1. Preferably, the voltage generation means 12 are designed or set up such that for each electrical angle between 0 ° and 359 ° (including 359 °) or in any case less than 360 °, at least one voltage pulse is generated, respectively.

The voltage generating means 12 are also designed such that all electrical angles greater than or equal to 360 ° (Φ ≧ 360 °) are identified by corresponding electrical angles (Φ -n × 360 °) between 0 ° and <360 °, reduced by integer multiples n of 360 °. In other words, herein, no distinction is made between electrical angles 15 ° and electrical angles 375 ° (= 15 ° +360 °).

The device 10 further comprises a measuring device 14, which is designed to measure at least one respective current value resulting from the voltage pulse generated by the voltage generating device 12. That is, during the voltage pulse, the current rises according to the azimuth angle of the rotor 2 or the magnetic field permanently generated by the rotor 2 of the permanent magnet synchronous machine 1. The voltage generating device 12 is preferably designed such that the respective current value is always measured at the end of the voltage pulse generated by the voltage generating device 12.

If a device 10 is required which operates particularly quickly, provision can be made for: voltage pulses are generated only at predetermined electrical angles with an angular spacing of more than 1 ° and the value of the current resulting therefrom is measured. For example, voltage pulses may be generated and current values measured at a total of ninety predetermined electrical angles (that is, at 0 °, at 4 °, at 8 °, etc.) at the same pitch between 0 ° and 360 °. If a particularly precise device 10 is required, provision can be made for: the voltage generating device 12 generates a plurality of (for example two, three or even more) voltage pulses at an angular interval of 1 °, and accordingly, a plurality of current values are measured by the measuring device 14 for the predetermined electrical angle. Advantageously, however, for each of the predetermined angles, the same number of voltage pulses is generated and the same number of current values is measured.

Advantageously, after each voltage pulse is generated, a pulse in the opposite direction is generated, so that the current decays as quickly as possible. Alternatively or additionally, after each generated voltage pulse has decayed and/or after the respective current value has been measured, a predetermined time period is waited before a next voltage pulse is generated by the voltage generation device 12, wherein the next voltage pulse may be generated with respect to or at the same predetermined electrical angle or at another electrical angle, for example, increased by 1 °. The predetermined time period is, for example, between 1 microsecond and 500 microseconds.

The voltage pulse may have a pulse height between 1 volt and 10 volts. The voltage generation device 12 can be set up such that voltage pulses are generated with a pulse duration of between 1 microsecond and 1000 microseconds. In this case, the voltage pulses are advantageously always generated by the voltage generating device 12 in such a way that the rotor 2 is not set in rotation, i.e. is rotated, by the voltage pulses.

The device 10 further comprises a computing means 16 which may be configured, for example, as a microcontroller, an Application Specific Integrated Circuit (ASIC), an FPGA or a processor and a memory of a computer. The computing means 16 are set up to: the current signal waveform is generated and/or stored according to an angle within one half of 360 °, for example within one half extending from 0 ° to <180 °.

Exemplary current signal waveforms for all measured current values are schematically shown in fig. 2, where the horizontal axis 81 shows the electrical angle from 0 ° to 360 ° (= 0 °) and the vertical axis 82 shows the current values.

The computing means 16 are also set up to: each current value measured at a predetermined angle within a further half of 360 ° (extending from 180 ° to <360 ° in the above example) is assigned to a corresponding predetermined angle within the half (from 0 ° to <180 °), which is staggered by 180 °. In the above example, correspondingly, the current value measured for electrical ground 180 ° is assigned to a predetermined electrical angle of 0 °, the current value measured for electrical ground 181 ° is assigned to a predetermined electrical angle of 1 °, and so on.

Now, by means of the calculation means 16, for storing the current signal waveform, on the basis of all current values assigned to a predetermined electrical angle within the half (from 0 ° to <180 °), a respective value of the current signal waveform for the predetermined electrical angle is calculated, for example by adding all assigned current values or by averaging. The result of this step is schematically shown in fig. 3.

A current signal waveform from 0 ° to <360 ° across the measured current value can be used in the case of a real electric machine, for example, by following the sequence

a + b*cos(φ) + c*cos(2φ) + d*cos(3φ) + e*cos(4φ) + ...

Where phi denotes the electrical angle and a, b, c, d and e are all coefficients, and where a and c are typically much larger than all other coefficients.

By adding the current values each at an angle of 180 ° (this addition is also performed when averaging), the "odd part" of cos (Φ), cos (3 Φ), etc. is eliminated, since for all odd n, cos (n × (Φ +180 °)) = -cos (n × Φ), etc. After this step, there is a maximum value, which can be clearly seen in fig. 3, within this half of the angle of 360 ° (for example from 0 ° to <180 °), which corresponds to the D-axis or D' axis in the coordinate system with respect to the stator.

Furthermore, a current signal waveform without an average value, the average value of which is zero, is generated by the calculation means 16. For this purpose, an average value of the stored current signal waveform may be determined, and the stored current signal waveform may be shifted by subtracting the calculated average value from all values of the stored current signal waveform, so as to obtain a current signal waveform without an average value. The computing means 16 are also set up to: an integral function of the current signal waveform without the mean value is calculated. In fig. 4, a curve 83 representing an integration function is exemplarily depicted.

The computing means 16 are also set up to: the azimuth angle of the rotor 2 is determined based on the calculated integral function 83. Preferably, this is achieved by determining the average value of the calculated integration function 83 (line 84 in fig. 4).

Furthermore, according to this preferred variant, a first angle value 85 is determined by the computing device 16, at which the calculated integral function 83 intersects the determined mean value 84 of the calculated integral function 83 from below to above. Preferably, the azimuth angle of the rotor 2 is determined by the calculation means 16 based on the determined first angle value 85.

In other words, the angle value at which the calculated integral function 83 intersects the determined mean value 84 of the calculated integral function 83 during the rise of the calculated integral function 83 from the low value towards the higher value is determined as the first angle value 85. In other words, the angle value at which the integration function 83 intersects the mean value 84 from below is the first angle value 85 in the graphical illustration shown in fig. 4.

Typically, the maximum of the function is determined by the mathematical derivative and determining the zero of the derivative. This approach may have the following disadvantages: in the case of noisy measured values, which are often present in practice for currents, the discrete derivatives do not provide clear zeros.

One great advantage of the apparatus 10 described herein is that: this maximum value corresponding to the D axis or D' axis is not determined by the derivative, but by means of an integral function. This is therefore possible because the stored current signal waveform is periodic and because the intersection of the integration function with the average of the integration function is at the same angle as the zero point of the derivative of the current signal waveform. The derivative of the cosine function is a sine function and the integral of the cosine function is also a sine function. The computing means 16 of the apparatus 10 make full use of this property. Integrating the detected current values is particularly advantageous, since the measurement error after integration is much smaller or even becomes zero, which measurement error is significantly amplified due to the discrete derivative.

After the determination of the first angle value 85, there is also the ambiguity already explained above, since the actual azimuth angle of the rotor 2 may now correspond either to the electrical first angle value 85 (Φ) or to the first angle value 85 increased by 180 ° (that is to say +180 °).

To resolve this ambiguity, the following is preferably taken: in each case, an electrical saturation pulse is generated not only at (or for) the determined first angle value 85 (Φ) of the electricity but also at (or for) the first angle value 85 (that is to say Φ +180 °) increased by 180 °, which electrical saturation pulse may be, for example, 50 volts or more, that is to say in each case generated by the voltage generating device 12. As described above with regard to the other voltage pulses, the current values can be measured at the end of the saturation pulse by the measuring device 14. The computing device 16 may be set up to: the two measured current values resulting from the saturation pulse are compared and the angle value at which the current value resulting from the saturation pulse is higher is determined as the azimuth angle of the rotor 2.

The computing device 16 may also be set up to: in addition to the maximum value of the current signal waveform, that is to say in addition to the first angle value 85, a second angle value 86 is also determined, which corresponds to the minimum value of the current signal waveform. The computing device 16 may be set up to: as a second angle value 86, an angle value is determined at which the calculated integral function 83 intersects the determined mean value 84 of the calculated integral function 83 during the fall of the calculated integral function 83 from the higher value to the lower value, that is to say at which the calculated integral function 83 intersects the determined mean value 84 in fig. 4 from above.

Advantageously, the azimuth angle of the rotor 2 is additionally determined on the basis of the determined second angle value 86 (Φ 2). I.e. the minimum value of the stored current signal waveform in fig. 3 is shifted by 90 deg. with respect to the maximum value. Thus, a third angle value Φ 3 may be determined which is equal to the second angle value 86 increased by 90 ° (that is Φ 3 = Φ 2+90 °), and the azimuth angle of the rotor 2 may be determined as the average of the first angle value 85 and the third angle value. Alternatively, the determination of the second angle value 86 can be dispensed with and the first angle value 85 can be determined simply by the computing device 16 as the azimuth angle of the rotor 2.

Alternatively, to resolve the ambiguity, the apparatus 10 may also be configured such that the calculation means 16 compares the value of the average or sum of the current values initially measured at the first angle value 85 with the value of the average or sum of the current values measured at the first angle value 85 raised by 180 °, and then determines an angle at which the average of the current values is higher or the sum of the current values is higher in the comparison as the azimuth angle of the rotor 2.

Fig. 5 shows a schematic flow diagram for illustrating a method for determining the azimuth angle of the rotor 2 of the synchronous machine 1 according to a further embodiment of the invention. The method according to fig. 5 can be carried out in particular with the device 10 described above and can be adapted in accordance with all the modifications, variants and extensions described with respect to the device 10 and vice versa.

In step S10, at least one voltage pulse is generated in each case at a predetermined electrical angle or at a predetermined electrical angle in a coordinate system fixed with respect to the stator of the stator 3 of the synchronous machine 1 when the rotor 2 of the synchronous machine 1 is stationary, that is to say when the synchronous machine 1 is out of operation. In this case, a corresponding electrical angle, which is increased by 180 °, is also preferably predetermined for each predetermined angle. Step S10 may be performed, inter alia, by the voltage generation means 12 of the device 10, as described above.

In step S20, each of the at least one corresponding current value resulting from the generated voltage pulse is measured. Step S20 may be performed, inter alia, by measuring device 14 of apparatus 10, as described hereinabove.

In step S30, the current signal waveform of the measured current value is stored, for example as described above with respect to the computing device 16. Preferably, the current signal waveform is made only according to an angle within one half of 360 °. In this case, the value for each predetermined angle within the half of 360 ° is determined not only from at least one current value measured for this predetermined angle but also from at least one current value measured at the predetermined angle increased by 180 °.

In step S40, a current signal waveform without an average value is generated, the average value of which is zero, for example, in such a manner that the stored current signal waveform is correspondingly shifted up or down. Alternatively, the current values on which the current signal waveforms are based can also be shifted correspondingly before storing them, that is to say reduced by the average value of these current values.

In step S50, an integration function 83 of the current signal waveform without the average value is calculated. In step S60, the azimuth angle of the rotor 2 is determined based on the calculated integral function 83. Steps S30, S40, S50, and S60 may be performed, inter alia, by the computing device 16 of the apparatus 10, as described above.

Although the present invention has been described above in terms of preferred embodiments, it is not limited thereto but can be modified in various ways and methods. In particular, the invention can be varied or modified in a multitude of ways without departing from the core of the invention.