DE102013223785A1 - Rotor for an electric machine and method for producing a rotor - Google Patents

Abstract

The invention relates to a rotor (1) for a brush-commutated electric machine, comprising: - an armature (2) with grooves (21) extending substantially transversely to its arrangement direction; and - a plurality of coil windings (5) guided through said grooves (21), said coil windings (5) being formed with varying electrical resistances; wherein the coil windings (5) have end connections (52) which extend along the front sides of the armature (2), wherein the end connections (52) lie one above the other in sections in the axial direction, the axial position of the end connections (52) of the coil windings (5). is selected relative to each other so that the difference between the maximum and minimum electrical resistance of the coil windings (5) is maximum, or that a measure of a deviation of the electrical resistances of the successively commutated coil windings (5) is minimized by a curve of a sinusoidal curve.

Description

Technical area

The invention relates to wound rotor for brush-commutated electrical machines, in particular rotor, which are provided with coil windings of different numbers of turns to perform a rotor position detection by evaluating a current signal through the coil windings.

State of the art

When winding a rotor for an electric machine, such as a rotor of a DC machine, coil sides of the individual coil windings are in corresponding grooves and are connected to one another via end connections. Due to the winding diagram usually used, the end connections cross each other and thus lie one above the other in the axial direction. This results in that the strands of the individual coil windings have different lengths, whereby - assuming the same number of turns - different winding wire lengths are required for each of the corresponding coil windings. This leads to a change in electrical resistance between the coil windings despite the same number of turns.

It can be provided that, in the case of electrical machines, a detection of a rotor position takes place by evaluating an electrical property of the coil windings of the wound machine component. In particular, the electrical characteristic depends on the electrical resistance of the respective coil winding and it may be provided to vary the electrical resistance of the individual winding coils, e.g. to provide with different numbers of turns. However, the desired effect of varying the electrical resistance may be influenced by the variations in the lengths of the strands of the coil windings caused by the superimposed end connections of the coil sides, so that an evaluation of the position information by means of the electrical resistance is impaired.

From the publication DE 102 13 383 A1 a method for winding a winding support with a winding wire is known, wherein to avoid a resistance ripple over the circumference of the winding before winding the winding wire on the winding support of the wire cross section of the winding wire is varied so that the electrical resistance of all wound with the winding wire coil windings approximately equal is.

The publication EP 2 186 183 B1 discloses an electric machine with grooves formed in a rotor in which individual conductor loops of electrical coils are arranged. The number of individual conductor loops of the coils is chosen such that the sequence of the number of conductor loops in the order of their commutation represents approximately a sinusoidal function.

It is an object of the present invention to provide a wound rotor for an electric machine, with which it is possible to perform a position detection in the electric machine by evaluating an electric variable relative to the coil windings of the rotor in a reliable manner. In particular, the rotor should ensure that its winding does not hinder or prevent electronic detection of the rotor position based on the electrical resistance of the coil windings. It is a further object to provide a method for producing a wound rotor, with which the rotor can be created with a reliable position detection of the electric machine by evaluating an electrical resistance of the coil windings of the rotor.

Disclosure of the invention

This object is achieved by the wound rotor for an electric machine according to claim 1 and by the electric machine and the method for manufacturing a rotor according to the independent claims.

Further advantageous embodiments are specified in the dependent claims.

• – einen Anker mit im Wesentlichen quer zu ihrer Anordnungsrichtung verlaufenden Nuten; und
• – mehrere durch die Nuten geführte Spulenwicklungen, wobei die Spulenwicklungen mit variierenden elektrischen Widerständen ausgebildet sind;

wobei die Spulenwicklungen Stirnverbindungen aufweisen, die entlang den Stirnseiten des Ankers verlaufen, wobei die Stirnverbindungen in axialer Richtung abschnittsweise übereinander liegen,
wobei die axiale Lage der Stirnverbindungen der Spulenwicklungen relativ zueinander so gewählt ist,
dass die Differenz zwischen dem maximalen und minimalen elektrischen Widerstand der Spulenwicklungen maximal ist, oder
dass ein Maß für eine Abweichung der elektrischen Widerstände der nacheinander kommutierten Spulenwicklungen von einem Verlauf einer sinusförmigen Kurve minimal ist. According to a first aspect, a rotor, in particular a rotor, is provided for a brush-commutated electric machine, comprising:

• An armature with grooves extending substantially transversely to its arrangement direction; and
• - A plurality of guided through the grooves coil windings, wherein the coil windings are formed with varying electrical resistances;

wherein the coil windings have end connections which run along the front sides of the armature, wherein the end connections lie one above another in the axial direction in sections,
wherein the axial position of the end connections of the coil windings is selected relative to one another,
that the difference between the maximum and minimum electrical resistance of the coil windings is maximum, or
a measure of a deviation of the electrical resistances of the successively commutated coil windings from a profile of a sinusoidal curve is minimal.

One idea of the above wound rotor is to provide it with coil windings having varying electrical resistance values to enable positional detection of the rotor by directly or indirectly evaluating the electrical resistance (eg, by a corresponding voltage and / or current measurement). Furthermore, the order in which the end connections of the individual coil windings overlap one another in the axial direction in the axial direction is adapted to the varying electrical resistance values. The adjustment can be made such that the difference between the maximum and minimum electrical resistance of the coil windings is maximum or that a measure of a deviation of the electrical resistances of the successively commutated coil windings from a curve of a sinusoidal curve is minimal. As a result, the best possible evaluation of the variation of the electrical resistance of the coil windings during a movement of the rotor with respect to a positional detection to be carried out can be ensured. Overall, it can be achieved by the above measures that the resistance variations resulting from the different lengths of the end connections compensate for the varying electrical resistances provided for the coil windings or attenuate their variation, which would impair the detectability of the rotor position.

• – einen variierenden Querschnitt eines Wicklungsdrahts für die Spulenwicklungen;
• – ein variierendes Material des Wicklungsdrahts;
• – ein zusätzliches Widerstandselement, das mit der Spulenwicklung verschaltet ist; und
• – eine variierende Anzahl der Windungen der Spulenwicklungen.

Furthermore, the varying electrical resistances of the coil windings may be determined by at least one of the following:

• A varying cross-section of a winding wire for the coil windings;
• A varying material of the winding wire;
• - An additional resistance element, which is connected to the coil winding; and
• - A varying number of turns of the coil windings.

According to one embodiment, the rotor may have a commutator for the position-dependent electrical energization of the coil windings.

It can be provided that the varying electrical resistances of the successively commutated coil windings along a predetermined course with a maximum and a minimum electrical resistance, in particular along a course of a sinusoidal curve, are selected.

In particular, the end connections of the coil windings with the minimum electrical resistance can be arranged closer to the front side of the armature, at least on sections lying one above the other end connections, than the end connections of the coil windings with the maximum electrical resistance.

Alternatively, the end connections of the coil windings may each have a different length at one end side of the armature, wherein the end connections of the coil windings with the minimum electrical resistance have a shorter length than the end connections of the coil windings with the maximum electrical resistance.

• – einen Anker mit im Wesentlichen quer zu ihrer Anordnungsrichtung verlaufenden Nuten; und
• – mehrere durch die Nuten geführte Spulenwicklungen, wobei die Spulenwicklungen mit variierenden elektrischen Widerständen ausgebildet sind;

wobei die Spulenwicklungen Stirnverbindungen aufweisen, die entlang den Stirnseiten des Ankers verlaufen, wobei die Stirnverbindungen in axialer Richtung abschnittsweise übereinander liegen, wobei die axiale Lage der Stirnverbindungen der Spulenwicklungen relativ zueinander so gewählt ist, dass beim Betrieb der elektrischen Maschine eine Stromwelligkeit einer Frequenz, die einer Harmonischen der Ordnung einer doppelten Polpaarzahl des Läufers bzw. einem Vielfachen davon entspricht, maximal wird. According to a further aspect, an electric machine is provided, wherein a rotor comprises:

• An armature with grooves extending substantially transversely to its arrangement direction; and
• - A plurality of guided through the grooves coil windings, wherein the coil windings are formed with varying electrical resistances;

wherein the coil windings have end connections which run along the front sides of the armature, wherein the end connections in sections are one above the other in the axial direction, wherein the axial position of the end connections of the coil windings relative to each other is selected so that during operation of the electric machine, a current ripple a frequency a harmonic of the order of a double pole pair number of the rotor or a multiple thereof corresponds to a maximum.

In this way it can be ensured that the proportion of the harmonics of the order of the double pole pair number of the rotor with respect to all harmonics is as large as possible, so that a reliable evaluation for position detection is ensured in this frequency range. At the same time, the harmonic of the order of twice the number of pole pairs of the rotor represents a relatively low frequency for the current ripple, which also allows a simple evaluation of the position of the rotor.

According to another aspect, there is provided a method of manufacturing a rotor for a brush-commutated electric machine, wherein an armature having grooves extending substantially transverse to its arrangement direction is wound with coil windings formed with varying electrical resistances, the winding being wound in a winding order is carried out so that end connections of the coil windings run along the end sides of the armature and in the axial direction in sections one above the other and so that the axial position of the end connections of the coil windings relative to each other is selected so that during operation of the electric machine, a current ripple frequency, the Order of a double pole pair number of the rotor or a multiple thereof corresponds to a maximum.

Furthermore, the varying electrical resistances of the coil windings may be represented by a varying cross section of a winding wire for the coil windings and / or by a varying material of the winding wire; and / or be determined by a varying number of turns of the coil windings.

Furthermore, the varying electrical resistances of the coil windings disposed one after the other in the arrangement direction along a predetermined path with a maximum and a minimum electrical resistance, in particular along a course of a sinusoidal curve, can be selected.

In particular, the end connections of the coil windings with the minimum electrical resistance can be arranged closer to the front side of the armature, at least at portions lying one above the other end connections, than the end connections of the coil windings with the maximum electrical resistance.

Brief description of the drawings

Embodiments are explained below with reference to the accompanying drawings. Show it:

1 a side view of a wound rotor for a DC machine;

2 a cross-sectional view of the rotor of 1 on a provided with the commutator end face;

3 a diagram indicating the course of a winding resistance of the coil windings depending on the winding order winding of the coil windings;

4 an example of a variation of the number of turns over the circumference of the rotor, so that the electrical resistances lie on a sinusoidal curve;

5 a representation of various variants, each showing a resulting electrical resistance of the successively arranged in the circumferential direction coil windings, wherein the respective electrical resistance of the varying electrical resistance and the electrical resistance of the respective length of the end connection of the respective coil winding results; and

6 a diagram showing an influence of the winding order and the number of turns on a current ripple over the speed.

Description of embodiments

1 shows a side view of a rotor 1 (Rotor) for an electric machine, in particular for a DC machine. The rotor 1 includes an anchor 2 that stuck to a rotor shaft 3 is arranged. The anchor 2 is with grooves running in the axial direction 21 provided for the respective recording of coil windings 5 serve.

Axially offset to the anchor 2 is a commutator 4 on the rotor shaft 3 provided, the circumferentially arranged commutator bars 41 having coil windings by means of commutator brushes (not shown) 5 at the anchor 2 to energize.

The anchor 2 is due to several coil windings 5 wound, each with two commutator blades 41 are connected for applying an electric current. The coil windings 5 are each by two grooves 21 led, where in the grooves 21 lying coil sides 51 the circulating coil windings 5 over forehead connections 52 at the axial ends of the anchor 2 connected to each other.

In the manufacture of the rotor 1 become the coil windings 5 one after the other into the grooves 21 wrapped so that the forehead connections 52 the coil windings 5 come to lie one above the other in the axial direction. The layer arrangement of the end connections 52 is determined by the winding order, which is usually fixed in conventional Bewicklungsvorrichtungen. Freely selectable, however, is the coil winding 5 , with the winding of the anchor 2 is started.

In 2 is schematically an end view of the with the commutator 4 provided end of the rotor 1 shown. You can see the position of each by two grooves 21 guided coil strands of the coil windings 5 , where the forehead connections 52 partially overlap. Due to the layer arrangement of the end connections 52 the individual coil windings 5 in the axial direction, the winding cross sections of the coil windings differ 5 (ie, through the coil winding in question 5 enclosed area), whereby the length of the winding wire of the respective coil winding 5 significantly depends on what position the forehead connection 52 the relevant coil winding 5 located.

Due to the varying length of the winding wires of the individual coil windings 5 Depending on the winding order in which the coil windings 5 on the anchor 2 have been wound, or depending on the coil winding 5 , with the winding of the anchor 2 started to be varied electrical resistances. In 3 In this regard, the rising electrical resistance of coil windings wound in the specified order (x-axis) F is by way of example 5 shown.

For a rotor position detection, an evaluation of an electrical size of the coil windings 5 be used. In particular, the electrical resistance of the coil windings 5 be designed differently, depending on a detected electrical resistance, the absolute position of the rotor 1 to detect in the electric machine. This can be done, for example, by adapting or varying a conductor cross-section of the winding wire for the coil windings 5 by varying a material of the winding wire or by varying the number of turns of the coil windings 5 be achieved. By providing coil windings 5 With varying number of turns, it is thus possible to adjust the electrical resistance. The position detection can then by evaluating the current by the commutator 4 contacted coil winding 5 respectively.

As already in the publication WO 2009/015930 described, it is advantageous if the electrical resistances in the circumferential direction of the rotor 1 adjacent coil windings 5 are arranged with respect to their commutation order KF along a course of a sinusoidal curve, so that when evaluating the electrical resistance to determine the rotor position higher order disturbances of an additional current ripple signal can be largely avoided or hidden. An example of such a design of the electrical resistances of successively commutated in a Kommutierungsreihenfolge KF coil windings 5 is in 4 shown.

For evaluation, a control device may be provided which by the rotor 1 detected flowing motor current and evaluates the current ripple located on the motor current. The current ripple initially have a main frequency, the commutation frequency of the commutator 4 depending on the speed of the rotor 1 equivalent. Furthermore, the current ripple is superimposed on a further frequency of the 2p-th order, resulting from the sinusoidal course of the resistance values of the coil windings 5 in combination with the induced voltage and due to the commutation results. From this, the current rotor position can be derived at any time.

Both due to the chosen winding order of the coil windings 5 as well as due to the choice of the number of turns of the individual coil windings 5 occurring variations of the electrical resistances superimpose each other and lead to resulting electrical resistances for each of the coil windings 5 , 5 shows a diagram that is exemplary of different variants of winding orders F of six circumferentially arranged coil windings 5 which have a profile of the electrical resistances with respect to their commutation order KF, which corresponds to a curve of a sinusoidal curve, the resulting electrical resistances in the commutation order KF of the coil windings 5 upon rotation of the rotor 1 indicates.

In five variants V1-V5 are different sequences for the winding of the anchor 2 with coil windings 5 at a correspondingly unchanged predetermined number of turns compared to that in the curve of 4 specified course of the corresponding electrical resistances. One sees strong variations between the progressions of the electrical resistances over the successively commutated coil windings 5 , For comparison, curve RK shows the course of the electrical resistance corresponding to the variation of the number of turns without regard to the winding order.

With regard to the evaluability of the electrical resistors would choose from the above variants, the winding order, from which the course of the electrical resistances of the coil windings 5 according to variant 5 results. There you get at for the sequentially commutated coil windings 5 electrical resistances almost along a sinusoidal course and with the largest possible change in the electrical resistance across the coil windings 5 , ie the largest difference between the maximum and the minimum electrical resistance of all coil windings 5 ,

6 shows a diagram illustrating the example of the course of the current ripples SW (difference between the amplitudes at the minima and maxima of the current waveform) and the speed n of the electric machine in the fourth and in the 20th order. It can be seen that high current ripples of the 20th order (curves K) can be achieved, especially at low speeds. With harmonics of the fourth order one obtains with the variant V5 the highest current ripple. The higher the current ripples in the lowest detectable order of the current ripple, the easier it is possible to carry out an evaluation of the rotor position.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10213383 A1 [0004]
• EP 2186183 B1 [0005]
• WO 2009/015930 [0036]

Claims (13)

Runner ( 1 ) for a brush-commutated electric machine, comprising: - an armature ( 2 ) with grooves extending substantially transversely to their arrangement direction ( 21 ); and - several through the grooves ( 21 ) guided coil windings ( 5 ), wherein the coil windings ( 5 ) are formed with varying electrical resistances; the coil windings ( 5 ) End connections ( 52 ), which along the end faces of the armature ( 2 ), the end connections ( 52 ) in sections in the axial direction, wherein the axial position of the end connections ( 52 ) of the coil windings ( 5 ) is selected relative to one another such that the difference between the maximum and minimum electrical resistance of the coil windings ( 5 ) is maximum, or that a measure of a deviation of the electrical resistances of the successively commutated coil windings ( 5 ) is minimal from a course of a sinusoidal curve. Runner ( 1 ) according to claim 1, wherein the varying electrical resistances of the coil windings ( 5 ) are determined by at least one of the following: a varying cross section of a winding wire for the coil windings ( 5 ); A varying material of the winding wire; An additional resistance element; and - a varying number of turns of the coil windings ( 5 ). Runner ( 1 ) according to claim 1 or 2, wherein the runner ( 1 ) a commutator ( 4 ) for the position-dependent electrical energization of the coil windings ( 5 ) having. Runner ( 1 ) according to one of claims 1 to 3, wherein the varying electrical resistances of the successively commutated coil windings ( 5 ) are selected along a predetermined course with a maximum and a minimum electrical resistance, in particular along a course of a sinusoidal curve. Runner ( 1 ) according to claim 4, wherein the end connections ( 52 ) of the coil windings ( 5 ) with the minimum electrical resistance at least on with other end connections ( 52 ) superimposed sections closer to the front side of the armature ( 2 ) are arranged as the end connections ( 52 ) of the coil windings ( 5 ) with the maximum electrical resistance. Runner ( 1 ) according to claim 4, wherein the end connections ( 52 ) of the coil windings ( 5 ) on one end face of the anchor ( 2 ) each have a different length, wherein the end connections ( 52 ) of the coil windings ( 5 ) with the minimum electrical resistance have a shorter length than the end connections ( 52 ) of the coil windings ( 5 ) with the maximum electrical resistance. Electric machine with a runner ( 1 ), the runner ( 1 ) comprises: - an anchor ( 2 ) with grooves extending substantially transversely to their arrangement direction ( 21 ); and - several through the grooves ( 21 ) guided coil windings ( 5 ), wherein the coil windings ( 5 ) are formed with varying electrical resistances; the coil windings ( 5 ) End connections ( 52 ), which along the end faces of the armature ( 2 ), the end connections ( 52 ) in sections in the axial direction, wherein the axial position of the end connections ( 52 ) of the coil windings ( 5 ) is selected relative to each other so that, during operation of the electric machine, a current ripple of a frequency corresponding to a harmonic of the order of a double pole pair number of the rotor or a multiple thereof becomes maximum. Electric machine according to claim 7, wherein the difference between the maximum and minimum electrical resistance of the coil windings ( 5 ) is maximum, or wherein a measure of a deviation of the electrical resistances of the successively commutated coil windings ( 5 ) is minimal from a course of a sinusoidal curve. Method for producing a runner ( 1 ) for a brush-commutated electric machine, wherein an armature ( 2 ) with grooves extending substantially transversely to their arrangement direction ( 21 ) with coil windings ( 5 wound with varying electrical resistances is wound, wherein the winding is performed in a winding order, so that end connections ( 52 ) of the coil windings along the end faces of the armature ( 2 ) and in the axial direction in sections one above the other and so that the axial position of the end connections ( 52 ) of the coil windings ( 5 ) is selected relative to each other so that, during operation of the electric machine, a current ripple of a frequency corresponding to a harmonic of the order of a double pole pair number of the rotor or a multiple thereof becomes maximum. Method according to claim 9, wherein the difference between the maximum and minimum electrical resistance of the coil windings ( 5 ) is maximum, or wherein a measure of a deviation of the electrical resistances of the succession commutated coil windings ( 5 ) is minimal from a course of a sinusoidal curve. Method according to claim 9 or 10, wherein the varying electrical resistances of the coil windings ( 5 ) are determined by at least one of the following: a varying cross section of a winding wire for the coil windings ( 5 ); A varying material of the winding wire; An additional resistance element; and - a varying number of turns of the coil windings ( 5 ). Method according to one of claims 9 to 11, wherein the varying electrical resistances of the successively commutated coil windings ( 5 ) along a predetermined course having a maximum and a minimum electrical resistance, in particular along a course of a sinusoidal curve. Method according to claim 12, wherein the end connections ( 52 ) of the coil windings ( 5 ) with the minimum electrical resistance at least on with other end connections ( 52 ) superimposed sections closer to the front side of the armature ( 2 ) are arranged as the end connections ( 52 ) of the coil windings ( 5 ) with the maximum electrical resistance.

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