JP3898611B2 - Resolver - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resolver that detects the rotational position of a motor.
[0002]
[Prior art]
An index unit is provided in an index unit used for machining a workpiece such as a machine tool, and a DD motor (direct drive motor) is directly connected to rotate the index table to a previously determined stop position. Accurately stopping the DD motor at the stop position depends on the detection accuracy of the resolver that detects the rotational position (rotation angle) of the DD motor. It is well known that the analog position signal output from the resolver includes a phase error. Therefore, in the conventional resolver (see Patent Document 1), in order to improve the detection accuracy, the DD motor measures the phase error of the analog position signal output from the resolver at every predetermined rotation speed in the manufacturing stage. Then, correction data for canceling the phase error is created. Then, correction data is added to the value obtained by converting the actual analog position signal output from the resolver into a digital signal, thereby improving the position detection accuracy of the DD motor.
[0003]
Prior art document information related to the invention of this application includes the following.
[0004]
[Patent Document 1]
JP2001 / 082982
[0005]
[Problems to be solved by the invention]
In the conventional resolver, since the position of the DD motor is detected using the correction data, a memory for storing the correction data is necessary, which causes an increase in cost. If correction data corresponding to a predetermined rotation speed is provided, the amount of correction data is enormous, and the cost for collecting the correction data also increases. Further, if the analog position signal output from the resolver is converted into a digital signal and corrected using correction data, the calculation is complicated and a microcomputer having a high processing speed is required, resulting in an increase in manufacturing cost. It is the cause.
[0006]
In addition, since the stator and the rotor constituting the resolver are made of metal, when the resolver is used in a place where the temperature of the external environment is relatively high, the stator and the rotor are thermally expanded. The relative phase error at each stop position also changes. When such a phase error occurs, it cannot be compensated by the correction data, which causes a decrease in the detection accuracy of the resolver.
[0007]
The present invention has been made paying attention to such problems existing in the prior art. The object is to provide a resolver that can improve detection accuracy despite its low cost.
[0008]
[Means for Solving the Problems]
(Invention of Claim 1)
According to the first aspect of the present invention, in a resolver for detecting a rotational position of a motor capable of setting a plurality of patterns of stop positions indexed at equal intervals in the circumferential direction, a plurality of rotor teeth are provided on the rotation shaft of the motor. A rotor having poles is provided, and a stator having a plurality of cores around which coils are wound in the circumferential direction is provided on the outer side of the rotor. The stator tooth poles arranged so as to face each other are protruded, and the total number of the rotor tooth poles is set to a common multiple of the index number having a plurality of patterns.
[0009]
According to this configuration, even if the pattern of the number of stop positions determined for the motor is changed, the electrical angles at the respective stop positions are all the same. If the electrical angle at each stop position is the same, the phase error of the resolver repeatedly appears for each cycle of the electrical angle, so that the relative phase error at each stop position is substantially the same. Therefore, it is not necessary to correct the value obtained by digitally converting the analog position signal output from the resolver, and it is not necessary to store correction data in the memory. As a result, it is possible to reduce the cost and improve the position detection accuracy of the motor.
[0010]
(Invention of Claim 2)
According to a second aspect of the present invention, in the resolver according to the first aspect, the stator is configured by laminating a plurality of steel plates in the thickness direction, and the stator is equally spaced in the circumferential direction. The gist of the present invention is that a three-phase / two-phase converter is provided for winding the arranged three-phase coils and converting an output signal output from the three-phase coils into an output signal for two phases. .
[0011]
With this configuration, when assembling the stator, the steel plates in each layer can be stacked so as to be displaced in the circumferential direction of the stator. Therefore, even when the steel plate has variations in forming, the magnetic flux density variations due to the forming error of the steel plate are eliminated, and the resolver detection accuracy is further improved.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, an index unit 11 provided in a machine tool or the like includes an indexing table 13 on which a workpiece 12 is placed. The indexing table 13 is a rotating shaft of a DD motor (direct drive motor) 14. 14a is directly connected. The DD motor 14 is rotated again after being temporarily stopped at a plurality of preset stop positions P1 to P8. As a result, when the indexing table 13 is turned at a constant indexing angle and the DD motor 14 is stopped, the workpiece 12 is processed at the respective stop positions P1 to P8.
[0013]
By rewriting a program for controlling the index unit 11, the number of indexes of the stop positions P <b> 1 to P <b> 8 set in the DD motor 14 can be changed by a plurality of patterns. In this embodiment, there are 12 patterns for the number of stop positions P1 to P8 set in the DD motor 14, and “2”, “3”, “4”, “5”, “6”, “8”, It can be changed to “10”, “12”, “15”, “16”, “24”, “30”. FIG. 1 shows only the index unit 11 in which the number of indexes of the stop positions P1 to P8 is “8”. If the index number is “8”, the index table 13 (the rotating shaft 14a of the DD motor 14) can be stopped at the stop positions P1 to P8 that are equally divided into eight (center angle is 45 °) in the same circumferential direction. Means that.
[0014]
As shown in FIG. 3, the resolver 20 is attached to the rotating shaft 14 a of the DD motor 14, and a gap is formed between the rotor 21 provided on the rotating shaft 14 a of the DD motor 14 and the outside of the rotor 21. The stator 22 is arranged. The resolver 20 is a multi-turn system, and when the rotor 21 rotates, the inductances of the first to sixteenth coils C1 to C16 wound around the stator 22 with the amount of rotation of one pitch of the rotor tooth pole 23 are electrically. It changes by one period (360 °) at the angle.
[0015]
The total number of rotor tooth poles 23 of the resolver 20 is set to 240 so as to be a common multiple of the number of indexes with a plurality of patterns. In the present embodiment, the total number of rotor tooth poles 23 is the least common multiple of the number of indexes having a plurality of patterns. In other words, the total number (240) of the rotor tooth poles 23 is set so that a value obtained by dividing one of the index numbers by a plurality of patterns becomes an integer value.
[0016]
The reason why the total number of resolvers 20 is 240 is as follows. For example, in the present embodiment, if the number of stops at positions P1 to P8 set in the DD motor 14 is “8”, the mechanical angle at each of the stops P1 to P8 is 45 as shown in FIG. In contrast, the electrical angles at the respective stop positions P1 to P8 are the same (0 °). This is because the value obtained by dividing the total number of rotor tooth poles 240 by the index number “8” is divisible by an integer (30), so that the electrical angle is a predetermined angle at the stop positions P1 to P8. Therefore, it does not change periodically. For reference, for example, when the total number of rotor tooth poles 23 is 242, the value obtained by dividing the total number of rotor tooth poles 23 by the index number is not divisible by an integer, and the fraction is 0.25 (242/8 = 30.25). In such a case, the electrical angle changes periodically with an angle of 90 °. That is, at each stop position P1 to P8, the electrical angle periodically changes in the order of 90 °, 180 °, 270, 360 °.
[0017]
In addition, the total number of rotor tooth poles 23 can be changed to an integer multiple of the least common multiple, for example, 480, 720, or a number other than the least common multiple of the number of indexes with a plurality of patterns. . If the total number of rotor tooth poles 23 is increased, the resolution of the resolver 20 can be increased. Of course, when the pattern of the number of indexes of the stop positions P1 to P8 set in the DD motor 14 is changed, the total number of rotor tooth poles 23 is 240 according to the change of the common multiple of these numbers of indexes. However, the present invention can be arbitrarily changed. For example, the pattern of the number of stop position indexes set in the DD motor 14 is “2”, “3”, “4”, “5”, “6”, “8”, “10”, “12”, “ In the case of “15”, since the least common multiple thereof is 60, the total number of rotor tooth poles 23 can be changed to an integral multiple of 60.
[0018]
A stator 22 is provided outside the rotor 21, and the stator 22 has first to sixteenth cores L <b> 1 to L <b> 16 that project radially from the inner peripheral surface toward the center. Stator tooth poles 24 arranged at the same intervals as the rotor tooth poles 23 are formed on the front end surfaces of the first to sixteenth cores L1 to L16.
[0019]
The first, fifth, ninth and thirteenth cores L1, L5, L9 and L13 are arranged at equal intervals with a central angle θ1 of 90 °. The second, third, and fourth cores L2, L3, and L4 are arranged at equal intervals with a center angle θ2 of 22 ° 7′30 ″ with respect to the first core L1. Sixth, seventh, and eighth The cores L6, L7, L8 are arranged at equal intervals with a central angle θ2 of 22 ° 7′30 ″ with respect to the fifth core L5. The tenth, eleventh, and twelfth cores L10, L11, and L12 are arranged at equal intervals with a center angle θ2 of 22 ° 7′30 ″ with respect to the ninth core L9. Further, the fourteenth, fifteenth, and fifteenth cores are arranged. The sixteenth cores L14, L15, and L16 are arranged at equal intervals with a central angle θ2 of 22 ° 7′30 ″ with respect to the thirteenth core.
[0020]
The first to sixteenth coils C1 to C16 are wound around the first to sixteenth cores L1 to L16 via coil bobbins 25 attached thereto. The odd-numbered coils, ie, the first coil C1, the fifth coil C5, the ninth coil C9, the thirteenth coil C13, the fifteenth coil C15, the eleventh coil C11, the seventh coil C7, and the third coil C3, Are connected in series. The even-numbered coils, ie, the second coil C2, the sixth coil C6, the tenth coil C10, the fourteenth coil C14, the sixteenth coil C16, the twelfth coil C12, the eighth coil C8, and the fourth coil C4 Are connected in series.
[0021]
When a positive excitation voltage (hereinafter referred to as + excitation voltage) is applied to the first coil C1 and the second coil C2, a sin position signal (analog position) is generated from the connection point between the thirteenth coil C13 and the fifteenth coil C15. Signal) is output. On the other hand, when a negative excitation voltage (hereinafter referred to as “−excitation voltage”) is applied to the third coil C3 and the fourth coil C4, cos from the connection point between the fourteenth coil C14 and the sixteenth coil C16. A position signal (analog position signal) is output. The sin position signal and the cos position signal are converted into digital signals by an RD converter (resolver digital converter) (not shown). If the RD converter has a resolution of 12 bits, the electrical angle (0 to 360 °) of one period of the resolver 20 is converted into a digital signal of 0 to 4095. Based on this digital signal, a controller (not shown) calculates the stop position of the DD motor 14.
[0022]
Therefore, according to the present embodiment, the following effects can be obtained.
(1) The total number of rotor tooth poles 23 in the resolver 20 is set to 240, which is a common multiple of “2”, “3”,. As a result, even if the index number of the stop positions P1 to P8 is changed from “8” to any other index number, and the index number is any pattern, the electricity at each stop position P1 to P8 of the index table 13 The angles can all be the same, 0 °. As shown in FIG. 2, if the electrical angle at each stop position P1 to P8 of the indexing table 13 is the same, the phase error of the resolver 20 repeatedly appears every electrical angle period (electrical angle 360 °). The relative phase error of the electrical angle at each stop position P1 to P8 is substantially the same. Therefore, it is not necessary to add correction data to the value obtained by digitally converting the position signal output from the resolver 20. Accordingly, since a memory for storing correction data in advance is not necessary, the cost of the resolver 20 can be reduced, and further, correction data is not necessary, and the cost for collecting the correction data is not required. In addition, if the relative phase errors of the electrical angles at the respective stop positions P1 to P8 can be made substantially the same, the stop accuracy of the index table 13, that is, the DD motor 14, can be improved.
[0023]
(2) Even if the phase error of the position signal changes under the influence of the temperature of the environment in which the resolver 20 is used, the phase error corresponding to the change is generated every electrical angle period (electrical angle 360 °). Appears repeatedly. Even in this case, since the relative phase error of the electrical angle at each of the stop positions P1 to P8 of the index table 13 does not change, it is possible to prevent the detection accuracy of the resolver 20 from being lowered without using correction data. The table 13 can be positioned with high accuracy.
[0024]
(Second Embodiment)
The second embodiment will be described focusing on the differences from the previous embodiment.
In this 2nd Embodiment, as shown in FIG. 5, the stator 22 is comprised by laminating | stacking the cyclic | annular steel plate 27 in the thickness direction. As shown in FIG. 4, the first to sixth U-phase cores U1 to U6, the first to sixth V-phase cores V1 to V6, and the first to sixth W-phase cores W1 to W6 protrude from the inner peripheral surface of the stator 22. It is installed. The cores U1 to U6, V1 to V6, and W1 to W6 are arranged with a central angle θ3 of 20 ° so as to repeat in the order of the U phase, the V phase, and the W phase.
[0025]
Connections of the coils Cu1 to Cu6, Cv1 to Cv6, and Cw1 to Cw6 provided corresponding to the cores U1 to U6, V1 to V6, and W1 to W6 are as follows. That is, the first, third, and fifth U-phase coils Cu1, Cu3, and Cu5 and the second, fourth, and sixth V-phase coils Cv2, Cv4, and Cv6 are connected in series, respectively. First, third, and fifth V-phase coils Cv1, Cv3, and Cv5 are connected in series with second, fourth, and sixth W-phase coils Cw2, Cw4, and Cw6, respectively. First, third, and fifth W-phase coils Cw1, Cw3, and Cw5 and second, fourth, and sixth U-phase coils Cu2, Cu4, and Cu6 are connected in series, respectively.
[0026]
When a positive excitation voltage is applied to the first U-phase coil Cu1 and a negative excitation voltage is applied to the sixth V-phase coil Cv6, a U-phase output signal from the connection point between the fifth U-phase coil Cu5 and the second V-phase coil Cv2 Is obtained. When a positive excitation voltage is applied to the first V-phase coil Cv1 and a negative excitation voltage is applied to the sixth W-phase coil Cw6, a V-phase output signal is generated from the connection point between the fifth V-phase coil Cv5 and the second W-phase coil Cw2. Is obtained. When a positive excitation voltage is applied to the first W-phase coil Cw1 and a negative excitation voltage is applied to the sixth U-phase coil Cu6, a W-phase output signal is generated from the connection point between the fifth W-phase coil Cw5 and the second U-phase coil Cu2. Is obtained. In short, a three-phase output signal can be obtained from the stator 22 of the present embodiment.
[0027]
As shown in FIG. 6, the output signals of the U phase, the V phase, and the W phase are converted into a sin position signal and a cos position signal by the three-phase / two-phase converter 29 connected to the resolver 20. The Specifically, it is converted into a sin position signal of the resolver 20 based on the output signals of the V phase and the W phase, and converted into a cos position signal of the resolver 20 based on the output signals of the U phase, the V phase, and the W phase. Is done. The sin position signal and the cos position signal thus obtained are converted into digital signals by an RD converter (not shown), and the respective stop positions P1 to P8 of the DD motor 14 are calculated.
[0028]
In the second embodiment, the three-phase / two-phase converter 29 employs a configuration in which the sin position signal and the cos position signal are obtained from the U-phase, V-phase, and W-phase output signals. The coils Cu1 to Cu6, Cv1 to Cv6, and Cw1 to Cw6 can be arranged at equal intervals along the circumferential direction. Therefore, when the plate-shaped material rolled by the press die is punched to obtain the steel plate 27, a slight forming error has occurred in the steel plate 27, but the steel plate 27 of each layer has a central angle θ3 of 20 °. By stacking so as to shift the position, the forming error of the steel plate 27 can be canceled. Therefore, the variation in the magnetic flux density due to the forming error of the steel plate 27 can be eliminated, and the position detection accuracy of the resolver 20 can be further improved.
[0029]
(Third embodiment)
As shown in FIG. 7, on the inner peripheral surface of the stator 22, the U phase coil corresponding to the U phase among the three phases + U1, + U2, + U3, -U1, -U2, -U3, and the V phase corresponding to the V phase. Coils + V1, + V2, + V3, -V1, -V2, -V3, and W-phase coils + W1, + W2, + W3, -W1, -W2, -W3 corresponding to the W-phase are provided. The coils + U1, + W1, + V1, + U2, + W2, + V2, + U3, + W3, + V3 are arranged at equal intervals with a central angle θ4 of 40 °. The remaining coils -V1, -U1, -W1, -V2, -U2, -W2, -V3, -U3, -W3 are respectively connected to coils + U1, + W1, + V1, + U2, + W2, + V2, + U3, + W3. , + V3, and the central angle θ5 is 19 ° 15 ′.
[0030]
U phase coil + U1, + U2, + U3, -U1, -U2, -U3, V phase coil + V1, + V2, + V3, -V1, -V2, -V3, W phase coil + W1, + W2, + W3, -W1, The phase difference between −W2 and −W3 is shifted by 120 °. The U-phase coils + U1, + U2, and + U3 that are indicated by plus signs have the same phase, and the U-phase coils -U1, -U2, and -U3 that are indicated by minus signs are also in the same phase. Furthermore, the U-phase coils + U1, + U2, + U3 indicated by plus and the U-phase coils -U1, -U2, -U3 indicated by minus are shifted in phase by 180 °. The remaining V-phase coils + V1, + V2, + V3, -V1, -V2, -V3, and W-phase coils + W1, + W2, + W3, -W1, -W2, -W3 have the same relationship as the U-phase. Yes.
[0031]
Here, U-phase coils (+ U1, + U2, + U3) and (-U1, -U2, -U3) having the same phase are defined as U-phase coil groups + U0 and -U0. V-phase coils (+ V1, + V2, + V3) and (−V1, −V2, −V3) having the same phase are defined as V-phase coil groups + V0 and −V0. W-phase coils (+ W1, + W2, + W3) and (−W1, −W2, −W3) having the same phase are defined as W-phase coil groups + W0 and −W0. FIG. 8 shows the output signals from the coil groups + U0, −U0, + V0, −V0, + W0, and −W0 in vector form.
[0032]
As shown in FIG. 8, in order to obtain the sin position signal and the cos position signal, output signals from the U-phase coil group + U0, -U0, the V-phase coil group + V0, -V0, and the W-phase coil group + W0, -W0 are used. If they are combined as vectors, 90 ° phase difference vectors A and B are obtained. That is, one of the 90 ° phase difference vectors A and B is the vector of the output signal (+ U) + (− V) + (− W) − (− U) − (+ V) − (+ W). It is obtained by synthesis. On the other hand, the other vector B is obtained by synthesizing the output signal (+ V) + (− W) − (− V) − (+ W).
[0033]
Therefore, in order to obtain the sin position signal and the cos position signal by connecting the coils of opposite phases in series, as shown in FIG. 7, each coil + U1, + U2, + U3, -V1, -W1, -U1, -U2 , -U3, + V1, + W1 are connected in series. At the same time, the remaining coils + V2, + V3, -W2, -W3, -V2, -V3, + W2, + W3 are connected in series.
[0034]
When a + excitation voltage is applied to the U-phase coil + U1 and a -excitation voltage is applied to the W-phase coil + W1, a sin position signal is generated from the connection point between the W-phase coil -W1 and the U-phase coil -U1. Is output. On the other hand, when a + excitation voltage is applied to the V-phase coil + V2 and a -excitation voltage is applied to the W-phase coil + W3, the cos position from the connection point between the W-phase coil -W3 and the V-phase coil -V2 A signal is output.
[0035]
Therefore, in the present embodiment, the three-phase / 2-phase shown in the second embodiment is employed in spite of the arrangement of the coils + U1, + U2,... The sin position signal and the cos position signal can be obtained without the need for the converter 29. Therefore, the manufacturing cost of the resolver 20 can be reduced.
[0036]
(Another embodiment)
The embodiment of the present invention may be modified as follows.
-In the said 3rd Embodiment, in order to output a sin position signal and a cos position signal, you may change the connection relation of a coil as follows. That is, as shown in FIG. 9, the coils + U1, + U2, + U3, -U1, -U2, and -U3 are connected in series. At the same time, the remaining coils + V1, + V2, + V3, -W1, -W2, -W3, -V1, -V2, -V3, + W1, + W2, + W3 are connected in series. When a + excitation voltage is applied to the U-phase coil + U1 and a -excitation voltage is applied to the U-phase coil -U3, it is possible to output a sin position signal from the connection point of both U-phase coils + U3 and -U1. It is. In contrast, if a + excitation voltage is applied to the V-phase coil + V1 and a -excitation voltage is applied to the W-phase coil + W3, a cos position signal is transmitted from the connection point between the W-phase coil -W3 and the V-phase coil -V1. It is possible to output.
[0037]
Next, in addition to the technical idea described in the claims, the technical idea grasped by the above-described embodiment will be described below.
(1) In a resolver for detecting a rotational position of a motor capable of setting a plurality of patterns of stop positions indexed at equal intervals in the circumferential direction, a rotor having a plurality of rotor tooth poles is provided on the rotating shaft of the motor A stator in which a plurality of cores each having a coil wound around the outer side of the rotor are arranged in the circumferential direction, and arranged at the front end surface of each core so as to face the rotor tooth poles at the same interval as the rotor tooth poles. The resolver is characterized in that a stator tooth pole is provided so as to be an integer obtained by dividing the total number of rotor tooth poles by the number of stop position indexes that can be changed.
[0038]
(2) In a resolver for detecting a rotational position of a motor capable of setting a plurality of patterns of stop positions indexed at equal intervals in the circumferential direction, a rotor having a plurality of rotor tooth poles is provided on the rotation shaft of the motor A stator in which a plurality of cores each having a coil wound around the outer side of the rotor are arranged in the circumferential direction, and arranged at the front end surface of each core so as to face the rotor tooth poles at the same interval as the rotor tooth poles. The stator tooth poles are projected, and the index number pattern is “2”, “3”, “4”, “5”, “6”, “8”, “10”, “12”, “15”. ”,“ 16 ”,“ 24 ”,“ 30 ”, when two or more are selected, the total number of the rotor tooth poles is set to a common multiple of the selected index number. .
[0039]
(3) In an index unit that includes a DD motor that rotates again after being temporarily stopped at a predetermined stop position, and that is directly connected to an index table on which a workpiece is placed on the rotation shaft of the DD motor, the rotational position of the DD motor 3. An index unit using the resolver according to claim 1 or 2 for detecting. With this configuration, the stop accuracy of the indexing table can be improved.
[0040]
【The invention's effect】
According to the present invention, the detection accuracy can be improved despite the low cost.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an index unit in a first embodiment.
FIG. 2 is also a diagram for explaining an electrical angle phase error at a stop position of an indexing table.
FIG. 3 is a schematic diagram of a resolver.
FIG. 4 is a schematic diagram of a resolver in the second embodiment.
FIG. 5 is a sectional view of the stator, similarly.
FIG. 6 is a view similarly showing a three-phase / two-phase converter.
FIG. 7 is a schematic diagram of a resolver in the third embodiment.
FIG. 8 is a diagram similarly showing vector-wise output signals in each phase.
FIG. 9 is another example of the third embodiment and is a diagram for explaining the connection relationship of coils.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 14 ... DD motor, 14a ... Rotary shaft, 20 ... Resolver, 21 ... Rotor, 23 ... Rotor tooth pole, 22 ... Stator, 24 ... Stator tooth pole, 27 ... Steel plate, 29 ... Three-phase / two-phase converter, P1- P8: Stop position, C1 to C16, Cu1 to Cu6, Cv1 to Cv6, Cw1 to Cw6, + U1, + U2, + U3, -U1, -U2, -U3, + V1, + V2, + V3, -V1, -V2, -V3 , + W1, + W2, + W3, −W1, −W2, −W3... Coil, L1 to L16, U1 to U6, V1 to V6, W1 to W6.

Claims (2)

In a resolver that detects the rotational position of a motor that can set a plurality of patterns for the number of stop positions that are equally spaced in the circumferential direction,
A rotor having a plurality of rotor tooth poles is provided on the rotating shaft of the motor, and a stator having a plurality of cores around which coils are wound is provided on the outer side of the rotor, and the rotor is provided on a tip surface of each core. A resolver characterized in that stator tooth poles are arranged so as to face the rotor tooth poles at the same interval as the tooth poles, and the total number of the rotor tooth poles is set to a common multiple of the index number. The stator is formed by laminating a plurality of steel plates in the thickness direction, and coils for three phases arranged at equal intervals in the circumferential direction are wound around the stator. The resolver according to claim 1, further comprising a three-phase / two-phase converter that converts an output signal output from the output signal into an output signal for two phases.

Images