JP2000209889A - Three-phase position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To deal with a plurality of poles using one type of position sensor by detecting a position detection signal through first and second sensor groups, logically operating the output signals to produce a three-phase signal and then selecting one type of signal. SOLUTION: A three-phase position detector comprises a first sensor group 10 for detecting the phase of a (2×N) pole machine every 60 deg. through three sensors having a phase shift of 120 deg., and a second sensor group 11 or a third sensor group 12 generating an M-bit gray code signal for dividing the edge interval of a three-phase signal from the first sensor group 10 into 2M subsections. The second, third sensor groups 11, 12 are connected through multipolar signal operating circuits 13, 14, 15 with a signal selection circuit 16 or connected directly with the signal selection circuit 16 in the case of the first sensor group 10. The signal selection circuit 16 can obtain a three-phase position detection signal corresponding to the number of poles based on a selection command from a selection signal holding circuit 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a three-phase position detecting device in a variable speed drive system for a synchronous motor.

[0002]

2. Description of the Related Art At the present time, with the performance of permanent magnets, motor drive devices using permanent magnets as field sources are being widely used. In such a drive device, as a general synchronous machine, a braking winding is applied in order to obtain stability. In the case of a permanent magnet synchronous machine, a braking winding is attached to a permanent magnet attached to an iron core surface. It is difficult to install.

[0003] To this end, as shown in FIG.
In the case where the motor 2 is driven and the braking winding is not provided, the motor becomes unstable. Therefore, as shown in FIG. 11, a magnetic pole position detector 3 is provided to control the voltage and current of the inverter 4 based on the magnetic pole position. This stabilizes and enables speed control. That is, in the configuration shown in FIG. 11, a function corresponding to the rectifier portion of the DC machine is realized by the magnetic detector 3 and the inverter 4, and is a so-called brushless DC motor.

In this case, a three-phase AC is generally used for the inverter 4 and the motor 2, and three-phase inverter control is performed. FIG. 12 shows a case in which three-phase inverter control is to be performed for a two-pole machine.
FIG. 5 is a time chart for obtaining a signal of 180 ° width with a phase difference shifted by °, and shows a signal for detecting a two-pole machine with a phase difference of 60 ° as a magnetic detection signal.

[0005] As a three-phase magnetic pole position detection method, it is ideally possible to measure an arbitrary phase using an absolute value encoder. However, the absolute value encoder is required to have high precision and is expensive. For this reason, as shown in FIG. 12, the output magnetic poles of Su, Sv and Sw are used to detect the step magnetic pole at an electrical angle of 60 °. Controls the direction of torque generation. In order to further accurately measure the phase of the section, the measurement is performed by combining an incremental encoder.

[0006]

However, even if the magnetism is detected in a 60 ° section based on the electrical angle, if the number of poles of the motor is different, only a corresponding type of magnetic sensor is created. There is a need. That is, multi-pole machines such as 4, 6, 8, and 12 poles are used in brushless DC motors, and it is necessary to provide magnetic pole sensors according to the number of poles. The large number of such models also leads to a problem that the manufacturing maker requires more time and effort for management and the amount of inventory increases.

The present invention has been made in view of the above problems, and has as its object to provide a three-phase position detecting device capable of coping with a plurality of poles with one type of position sensor.

[0008]

According to a first aspect of the present invention, there are provided three sensors having a characteristic in which a position detection signal for outputting a binary signal in a 180 ° section with respect to a rotation angle is shifted by 120 °. Thus, the first sensor group capable of detecting the phase at every 60 ° of the (2 × N) pole machine (N is a natural number) and the first sensor group 3
A second sensor group capable of generating an M-bit gray code signal that divides a 60 ° section, which is the edge interval of the phase signal, into 2 M (M is a natural number), a first sensor group, and a second sensor group (2 × N) ×
An arithmetic unit that creates a three-phase signal equivalent to 2 ^M poles,
It has a function of selecting one three-phase signal from three-phase position detection signals of the first sensor group and three multi-phase signals corresponding to M multipoles calculated from the first and second sensor groups. It is characterized by the following.

According to a second aspect of the present invention, a position detection signal for outputting a binary signal in an interval of 180 ° with respect to the rotation angle is used as an output signal having an angle of 120 °.
(2 ×)
N) A first sensor group capable of detecting a phase at every 60 ° of a pole machine (N is a natural number), and a 60 ° section, which is an edge interval of a three-phase signal of the first sensor group, is 2 M (M Is a natural number), a second sensor group capable of generating an M-bit gray code signal, and a 20 ° width position output that divides a 60 ° section, which is an edge interval of a three-phase signal of the first sensor group, into three equal parts. 3rd to do
By performing logical operation on output signals of the first sensor group, the second sensor group, and the third sensor group, (2 × N)
A computing unit for producing a three-phase signal corresponding to × 3 poles or (2 × N) × 6 poles, these three-phase position detection signals of the first sensor group, the first, second and third sensors A function of selecting one three-phase signal from three-phase signals corresponding to multi-poles obtained by calculation from the group.

A third aspect of the present invention includes a sensor and an arithmetic unit capable of detecting a three-phase signal position corresponding to a plurality of poles.
It has a function of selecting one type of signal from the phase position detection signal, is capable of inputting a selection signal from the outside, and has a selection signal holding circuit for storing the setting signal in a nonvolatile memory or the like. It is characterized by the following.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, an example of an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an example in which a three-phase position signal generating mechanism is constituted by a slit plate 9 and a position sensor. In this figure, the position of the position sensor is indicated by an arrow, and the slit plate 9 is developed linearly so that the phase difference can be easily recognized. That is, while slits corresponding to a width of 180 ° are formed in the slit plate 9, Su, Sv, and Sw of the position sensors are arranged with a phase difference of 120 °, and
Ba, Bb, and Bc, which are other position sensors, are arranged with a phase difference of 90 ° with respect to Su, Sv, and Sw.

In the configuration shown in FIG. 1, when the slit plate 9 moves rightward in the drawing due to the rotation of the motor, the sensors Su, Sv, Sw use the 180 ° width for 120 °.
2 is obtained, and the sensors Ba, Bb, and Bc also have a 120 °
A detection signal shifted by ° is obtained. And the sensor S
A detection signal is output between u, Sv, Sw and Ba, Bb, Bc, for example, with a phase difference of 90 ° between Su and Ba, and with a phase difference of 30 ° between Ba and Sv. Here the sensor S
u, Sv, Sw and Ba, Bb, Bc are, for example, two-pole three-phase magnetic pole detectors. In this case, if the length of the slit is N times, it can be extended to an encoder of 2 × N poles.

Next, a three-phase detection signal shifted by 30 ° in a 90 ° width corresponding to the four magnetic poles by the six position detection sensors is obtained by the lower calculation of FIG. That is,
According to the following formula, 3 shifted by 30 ° at 90 ° width equivalent to 4 poles
A phase magnetic pole signal can be obtained. Su (4P) = SuExorBaSv (4P) = SwExorBcSw (4P) = SvExorBb where Exor is an exclusive OR operator.
In practice, the number of poles of the motor to which the sensor is attached is fixed, so it is necessary to select and output either a 2-pole or 4-pole signal, and a selection circuit for that is necessary as described later. Becomes

In FIG. 1, a sensor capable of selecting between two poles and four poles is made possible by six position sensors.
3 to 5 show examples in which the number of position sensors is reduced. In Figure 4, four position sensors Su has two types of slits, Sv, is performed Sw, the position detection of the 2-pole and 4-pole at B _4. In FIG. 5, there is only one kind of slit, but five position sensors Su, Sv, Sw, B _4a , B _4
4b is provided to detect the positions of two poles and four poles.
In each configuration, as shown in the time chart of FIG. 3, four position sensors Su, Sv, and Sw are provided.
In the case of a pole, a fourth detection element signal B is further generated, and the detection element signal B is 60 °, 180 °, and 300 °.
A detection signal B is obtained in a total of 60 ° sections 30 ° back and forth so as to straddle the angle of. In FIG. 4, the detection signal B is obtained by a slit. In FIG. 5, the detection signal B is obtained by taking AND of the position sensors B _4a and B _4b .

Specifically, the detection signal B and the position sensor S
u, Sv, and Sw are converted into waveforms using a logic circuit to obtain four-pole signals. Table 1 below is a truth table of the conversion, and based on this table, the four-pole Su (4P), Sv (4
P) and Sw (4P) can be obtained.

[0016]

[Table 1] Then, in order to obtain a conversion equation from this truth table, all the conditions (terms indicated by the middle product in the following equation) for which the output is "1" may be described as a sum. In the following equation, * is a logical product, + is a logical sum,
And / represents logic inversion.

[0017]

Although the above equation has a complicated form, it can be easily realized by a logic operation element such as a gate array or a PLD.

Thus, the number of types of the detecting elements and the slits can be reduced, and the position can be detected by the logic logic.

Although the above description has been made by limiting the number of poles to two and four, a signal generating mechanism with (2 × 2 ^M ) poles can also be obtained. In this case, the 60 ° section is defined as M
Similar division may be performed using a gray binary code of bits, a truth table may be created, and an arithmetic expression may be derived.

FIG. 6 shows an extended example of a signal generating mechanism corresponding to eight poles where M = 2. As shown in FIG.
The signals B (4P) and B (8P) shown in FIG. 6 can be generated by adding a slit to the slit plate as shown in FIG. In this manner, the 60 ° section can be divided into four equal parts, and detection signals Su (8P), Sv (8P), and Sw (8P) corresponding to eight poles can be obtained. Then, a signal of (2 × 2 ^M ) poles can be obtained by sequentially repeating this method.

FIGS. 3 to 5 and 6 show examples in which two poles are converted to four poles or eight poles. However, in practice, six poles or twelve poles (2 × 2 ^M ) are used. There are other pole numbers. In this case, since it is necessary to further divide the 60 ° section into three equal parts, unlike the case of expanding to four poles or eight poles shown in FIG. 6, an example of the four poles shown in FIG. 20 °
The detection signals Su (6P), Sv (6P), and Sw (6P) shifted by 20 ° are added so as to add a signal having a width. As a result, a detection signal corresponding to six poles can be obtained. In this case, as can be seen from FIG. 7, the number of position sensors is 5, and three types of slits are required.

FIG. 8 shows a detection signal of 12 poles. The four poles B4 shown in FIG. 3, the eight poles B8 shown in FIG. 6, and the six poles shown in FIG.
By additionally providing a slit of 20 ° width every 60 ° on the pole B6, it is possible to obtain detection signals Su (12P), Sv (12P), Sw (12P) of 30 ° width in increments of 10 °.

In this way, a detection signal can be obtained by the arrangement of the detecting elements and the slits in the form of (2 × 2 ^M ), that is, 4 poles, 8 poles... Detection signals such as 6 poles 12 poles can be obtained.

FIG. 9 shows a magnetic pole position detection block in each of the examples up to now. That is, the detection elements Su, S
v, Sw, and Ba, Bb, Bc (2 × N) first
Sensor group 10, B ₄ and the slit arrangement and B _4b. Second sensor group 11 consisting of B _4a, or B (6P) and B (12P)
And a third sensor group 12 having a slit arrangement, and the second and third sensor groups are provided with multi-pole signal operation circuits 13, 14, 15
Or the first sensor group 10 is directly connected to a signal selection circuit 16, which obtains a three-phase position detection signal according to the number of poles based on a selection command from a selection signal holding circuit 17. be able to. In actual use, only one necessary type is selected and output from a plurality of multi-pole signals generated corresponding to the number of poles of the motor to be combined. Of course, it is preferable to transmit after selection inside the sensor also from the limitation of the number of transmission lines. At present, there are storage elements such as non-volatile RAM and the drive unit has a built-in microcomputer, so the microcomputer sends a selection signal of the number of poles to the sensor and stores it on the sensor side. Unlike a case where a dynamic switch or the like is used, there is no mechanical work and no mistake such as forgetting to set.

[0026]

According to the present invention as described above, the following effects can be obtained. In a three-phase position sensor, a plurality of multi-pole signals can be created. Thus, the number of slits and sensor elements can be reduced as compared with a configuration in which a plurality of three-phase circuits are simply incorporated. In addition, 1
Since a single sensor can be applied to a motor having a plurality of poles, it is possible to reduce administrative costs due to the reduced number of models.

[Brief description of the drawings]

FIG. 1 is an arrangement configuration diagram for expanding a two-pole sensor to four poles in an example of an embodiment of the present invention.

FIG. 2 is a time chart according to FIG. 1;

FIG. 3 is a time chart in a case where position detection of two poles and four poles is possible.

FIG. 4 is a diagram illustrating an example of an arrangement configuration for obtaining a signal shown in FIG. 3;

FIG. 5 is a diagram showing an arrangement of another example for obtaining the signal shown in FIG. 3;

FIG. 6 is a time chart when the position detection of eight poles is possible.

FIG. 7 is a time chart in a case where position detection of six poles is possible.

FIG. 8 is a time chart when the position of 12 poles can be detected.

FIG. 9 is a block diagram of a position detection.

FIG. 10 is a diagram showing a driving method of the synchronous machine.

FIG. 11 is a diagram showing a driving method using magnetic pole position detection.

FIG. 12 is an explanatory diagram of an example of a magnetic pole detection signal.

[Explanation of symbols]

 9 Slit plate 10, 11, 12 Sensor group 13, 14, 15 Multi-signal operation circuit 16 Signal selection circuit 17 Selection signal holding circuit

Claims (3)

[Claims] 1. A position detection signal for outputting a binary signal in a 180 ° section with respect to a rotation angle is converted into a (2 × N) pole machine by three sensors having characteristics in which the angle is shifted every 120 °. N is a natural number) A first sensor group capable of detecting a phase at every 60 °, and a 60 ° section which is an edge interval of a three-phase signal of the first sensor group is divided into 2 M (M is a natural number). By performing a logical operation on the output signals of the second sensor group and the first sensor group and the second sensor group that can generate an M-bit gray code signal of 3 bits corresponding to (2 × N) × 2 ^M poles An arithmetic unit for generating a phase signal; a three-phase position detection signal of the first sensor group;
And a function of selecting one three-phase signal from three M-phase three-phase signals obtained by calculation from the second sensor group. 2. A (2 × N) pole machine comprising a position detection signal for outputting a binary signal in a 180 ° section with respect to a rotation angle, and three sensors having characteristics shifted at every 120 °. (N
Is a natural number), and a 60 ° section which is an edge interval of a three-phase signal of the first sensor group is divided into 2 M (M is a natural number). A second sensor group that can generate an M-bit gray code signal; and a third sensor that outputs a 20 ° -wide position that divides a 60 ° section, which is the edge interval of the three-phase signal of the first sensor group, into three equal parts. By performing logical operation on the output signals of the first sensor group, the second sensor group, and the third sensor group, (2 × N) × 3 poles and (2 × N)
N) a computing unit that creates a three-phase signal equivalent to 6 poles; a three-phase position detection signal of the first sensor group;
And a function of selecting one three-phase signal from the multi-pole equivalent three-phase signal calculated from the second and third sensor groups. 3. A sensor or arithmetic unit capable of detecting the position of a three-phase signal corresponding to a plurality of poles, having a function of selecting one kind of signal from a plurality of three-phase position detection signals, and selecting from outside. A three-phase position detecting device capable of inputting a signal and having a selection signal holding circuit for storing a setting signal in a nonvolatile memory or the like.