JP2002064993A - Position detector for motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize compensation for positional error and improvement of position accuracy by arithmetic process of a sensor output for detection of rotor magnetic pole position of a 3-phase motor. SOLUTION: An average value of the calculated value and an actually measured value is obtained from an output of a rotor magnetic pole position detecting sensor of the 3-phase motor. As a result, positional (phase) displacement is compensated and rotating accuracy of the motor can also be improved by feeding a compensation signal to the motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor magnetic pole position detector for a three-phase brushless DC motor (hereinafter referred to as "motor").

[0002]

2. Description of the Related Art In recent years, motors used in various fields include:
High efficiency, low vibration, and miniaturization are being demanded.

In order to meet these requirements, it is necessary to accurately output the energization timing to each phase of the motor.
The energization timing is greatly affected by the mounting position accuracy of the Hall element for detecting the position of the magnet rotor.

Further, as the size of the motor decreases, the diameter of the rotor magnet decreases, and the pitch of the magnetic poles decreases. In addition, the number of poles tends to be increased for the purpose of improving motor performance, and the magnetic pole pitch width becomes smaller.

FIG. 3 shows an example of a conventional motor structure, wherein 1 is a stator core, 2 is a winding, 3 is a rotor magnet, 4 is a hall element, 5 is a motor housing, 6 is a ball bearing, and 7 is a print. It is a substrate. The three Hall elements 4 are arranged on the printed board so as to have a predetermined positional relationship with the teeth of the stator core 1.

FIG. 4 shows a general position signal processing circuit using Hall elements. The outputs of three Hall elements 4 for detecting three-phase position signals are amplified by Hall amplifiers 8 and then energized by a zero-cross comparator 9. Converted to a signal.

FIG. 5 shows a general operation timing of one phase of the position signal processing circuit using the Hall element shown in FIG. 4, where 10 is an induced voltage waveform of one phase with a motor, and 11 is an output of the Hall amplifier 8. Voltage waveform, 12 is Hall amplifier 11
Is an energization signal obtained by zero-cross-comparing the output of FIG. Here, as described above, the deviation of the phase (position) relationship between the one-phase induced voltage 10 and the energization signal 12 of the motor greatly affects the motor efficiency and vibration.

In order to ensure the accuracy of the phase (position) relationship, the following contrivance has been made in FIG.
The stator core 1 and the printed board 7 are mounted on the basis of the motor housing 5, and the printed board 7 is provided with positioning holes corresponding to the external dimensions of the Hall element 4. However, there is a problem of the processing accuracy of the printed circuit board and the tolerance of the external dimensions of the Hall element itself, and there is a gap between the positioning hole and the Hall element 4, which deteriorates the positional accuracy.

To improve the position accuracy of the Hall element, there is a method of finely adjusting the printed circuit board 7 on which the Hall element 4 is mounted by rotating the printed circuit board 7 with respect to the center of the motor housing 5.

[0010]

However, in the above-described conventional configuration, the positional accuracy between the Hall elements cannot be improved.

As an example, the inner diameter of the rotor magnet is 40 mm.
When 16 poles are magnetized on the inner circumference of, the width of one pole is about 8m
m, which is 180 ° in electrical angle. To operate the motor with high accuracy, the position detection accuracy is required to be an electrical angle of ± 5 ° or less. If this is converted into a machine size, it will be ± 0.22 mm or less, and it cannot be easily realized if component tolerances are accumulated.

In addition, it is very difficult to secure the positional accuracy when the tolerance of the external case size of the Hall element itself and the positional accuracy of the Hall element chip with respect to the case are taken into consideration.

A guide is provided on a printed circuit board, a first Hall element is mounted on the basis of the guide, and the positioning of the motor core with respect to the motor is performed based on the guide. The target position can be secured to some extent. However, there remains a problem of alignment between the first Hall element and the second and third Hall elements. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and has as its object to improve the accuracy of a position detector by correcting the influence of positional accuracy variation between Hall elements in a circuit.

[0014]

In order to achieve this object, in the present invention, the output voltage of each Hall element is made sinusoidal in consideration of the arrangement distance between the rotor magnet and the Hall element and the method of magnetizing the rotor magnet. By providing a guide on the printed circuit board, mounting the first Hall element on the basis of the guide, and performing positioning with the motor stator core based on the guide, the stator core and the first The following means are provided on the premise that the mechanical positions of the Hall elements are secured to some extent and that a uniforming circuit is provided so that the output voltage value of each Hall element becomes substantially the same value.

The output voltages of three Hall elements arranged so as to have a phase difference of 120 ° after the Hall amplifier are obtained. The first Hall element output is eu = sin θ, and the second Hall element output is ev = sin. (Θ−120 °), the output of the third Hall element is eu = sin (θ−240 °), eu
, Ev and ew are sine waves and have a phase difference of 120 degrees from each other, so that the following relationship is established: eu + ev = −ew (1) eu + ew = −ev (2) However, since the angle at which the Hall elements are actually arranged is different from 120 degrees, the output of the third Hall element is ew 'or the output of the second Hall element is ev'. Therefore, there is a difference between the value of the theoretical ev calculated from the sum of the output eu of the first Hall element and the output ew of the third Hall element from the equation (2) and the value of the actually output ev. If the average value of the value and the actual value is obtained, the error can be reduced because the average value can be closer to the theoretical value than the actual value. That is the principle of the present invention. The present invention provides a circuit for calculating an output corresponding to an amplified output of another Hall element from a sum of amplified outputs of two Hall elements, an output of the circuit, and another Hall. An arithmetic processing circuit comprising a circuit for calculating an average value of the output of the three elements and the output of the three elements is processed by an arithmetic processing circuit to reduce the mounting error of the Hall element.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an arithmetic processing circuit of a three-phase Hall element 4 to which the present invention is applied. Reference numeral 8 denotes a Hall amplifier that amplifies the output of the Hall element 4, 13 denotes an addition amplifier that adds the output of the Hall amplifier 8 between two phases, and 14A denotes an addition amplifier 13
And an addition amplifier 14B for adding the output of the Hall amplifier 8 before input to the addition amplifier with a gain of 1/2. Reference numeral 15 denotes a uniformizing circuit for reducing variations in output voltages of the three Hall elements 4.

In the circuit of FIG. 1, the output eu of the U-phase Hall amplifier 8u and the output ev of the V-phase Hall amplifier 8v are added by the addition amplifier 13a, and the output eu + ev of the addition amplifier 13a and the output of the Hall amplifier 8v. Is input to the addition amplifier 14A, and the addition amplifier 13
a circuit for inverting the output of a, a circuit for receiving the output of the Hall amplifier 8v, a circuit for adding the output of the inversion circuit and the output of the Hall amplifier 8v, and a multiplication circuit for halving the output of the addition circuit And the summing amplifier 14
The output Ev of A is output. The output eu of the U-phase Hall amplifier 8u and the output of the V-phase Hall amplifier 8v are added to the addition amplifier 1
3b, the output of the addition amplifier 13b is input to the addition amplifier 14b, and the addition amplifier 13b is
b, a circuit for receiving the output of the Hall amplifier 8w, a circuit for adding the output of the inversion circuit and the output of the Hall amplifier 8w,
A multiplication circuit for doubling the output, and outputs the output Ew of the addition amplifier 14b.

When the processing of the arithmetic processing circuit of the present invention shown in FIG. 1 is expressed by a mathematical expression, the output eu of the first Hall element after the Hall amplification is performed by the first Hall element via the printed circuit board. Since this output eu is used as a reference because it is arranged at a position corresponding to the reference position, corrected outputs of the other phases V-phase and W-phase are calculated based on this eu. Eu = eu (1) Ev = [-(eu + ew) + ev] / 2 ... 2 (2) Ew = [-(eu + ev) + ew] / 2 ... 3 (3) Output of Hall amplifier 8u Eu, the output Ev of the addition amplifier 14A and the output of the addition amplifier 14b are input to the three zero-cross comparators 9 to obtain output signals.

FIG. 2 is a simulation of the variation of the output of the Hall amplifier from eu, ev, ew, and Ew. The horizontal axis represents the motor electrical angle, and the vertical axis represents the output voltage of the Hall element after amplification. Reference numeral 20 denotes eu, which has an ev of 21 with a 120 ° phase delay, and an ew of 22 with a 240 ° phase delay (120 ° phase advance). This curve group shows curves in a case where the Hall elements are arranged at intervals of exactly 120 degrees. On the other hand, 23 is a curve when ew is delayed by 10 °, and the zero cross point is 70 °.
It is. Reference numeral 24 denotes a curve when ew is advanced by 10 °, and the zero cross point is 50 °. That is, if the position of the Hall element is shifted, the zero cross point moves.

Table 1 shows the combinations of the electrical angle differences of eu, ev and ew with respect to eu, where ev is ± 10 °, e
When w deviates by ± 10 °, combinations of 1 to 6 are obtained. Table 1
In the case of the first combination, since eu is the reference position, when the angle difference is 0, the angle difference of ev is 110 degrees, and when the angle difference of ew is 230 degrees, curve 1 is obtained. Similarly, in the case of the combination No. 2, eu is an angle difference of 0 and ev is 12
Curve 2 is obtained when 0 degrees and ew are 230 degrees. As described above, the angle difference between ev and ew is given based on eu, and the correction output Ew output is 2 in FIG.
6 are six curves represented by 5. The zero cross points of these six curves are all within the range of 50 ° to 70 °, indicating that the ew positional deviation has been corrected. Table 1
Electrical angle difference combination table (unit of angle) Although not shown in the drawing, similarly, from the curve of Ev, e
It can be simulated that the displacement of v is also corrected.

The concept of the embodiment of the present invention described above can be used not only for a rotor position detector of a three-phase brushless DC motor but also for an encoder having a three-phase sinusoidal output. It goes without saying that the present invention is also applied to a sensor that can be converted into a mechanical angle electric signal by a magnetic sensor or an optical sensor other than the element.

[0022]

As described above, according to the present invention, it is possible to greatly correct the mechanical displacement between the respective phases of a sensor having a three-phase sinusoidal output. It is possible to greatly improve motor efficiency, vibration, and the like.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an arithmetic processing circuit used in a motor position detector according to the present invention.

FIG. 2 is a simulation diagram for a variation in a mounting position of a Hall element of the motor position detector according to the present invention.

FIG. 3 is a structural view of a conventional motor.

FIG. 4 is a diagram of a conventional waveform processing circuit.

FIG. 5 is an operation timing chart of the waveform processing circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator core 2 Winding 3 Rotor magnet 4 Hall element 5 Motor housing 6 Ball bearing 7 Printed circuit board 8 Hall amplifier 9 Zero cross comparator 10 Motor induced voltage waveform 11 Hall amplifier output voltage waveform 12 Conduction signal 13 Addition amplifier 14 Addition amplifier 15 Uniform circuit 20 eu voltage waveform 21 ev voltage waveform 22 ew voltage waveform 23 ew 10 ° phase delayed voltage waveform 24 ew 10 ° phase advanced voltage waveform 25 Ew variation curve group

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 11/00 H02P 6/02 351N 29/08 H02K 11/00 CF term (Reference) 2F063 AA35 CA40 DA05 DD04 EA03 GA52 GA68 KA02 KA04 LA22 LA30 2F077 AA11 AA49 CC02 NN04 NN24 PP12 QQ07 TT02 TT35 TT59 5H019 AA04 AA06 BB01 BB05 BB15 CC04 DD01 5H560 BB04 BB12 DA02 RR03 TT05 TT07 5H07 A01 BB07 BB07 TT07 5H611 A01

Claims (2)

[Claims] 1. A three-phase brushless motor in which three rotors are arranged with a phase difference of 120 degrees in electrical angle to detect a rotor magnetic pole position.
And equalizing circuit means for taking out output voltages of the three Hall elements in a sine wave shape and reducing variations among the output voltages of the three Hall elements. Is converted into a rotor magnetic pole position signal by a zero-cross comparator. In the motor magnetic pole position detector, the output of the first Hall element among the three Hall elements is eu, and the output of the second Hall element is e.
v, the output of the third Hall element is ew, and circuit means for arithmetically processing the output of each Hall element is provided. The output of each Hall element is calculated by the arithmetic processing circuit means as Eu = euEv = [ − (Eu + ew) + ev] / 2 The first Hall element output Eu whose position has been corrected by processing so that Ew = [− (eu + ev) + ew] / 2, and the second Hall element output E whose position has been corrected.
(v) calculating a position-corrected third Hall element output Ew and converting the position-corrected Hall element outputs into magnetic pole position signals by a zero-cross comparator; 2. A sensor comprising: three sensors arranged to obtain a three-phase sinusoidal output with a phase difference of 120 electrical degrees to convert a mechanical angle into an electrical signal; and output voltages of the three sensors. A conversion circuit for converting the output voltage of the three sensors into a square wave signal by a zero-cross comparator, a uniforming circuit means for reducing a variation between output voltages of the three sensors, and a first of the three sensors. The output of the sensor is e
u, the output of the second sensor is ev, the output of the third sensor is ew, and arithmetic processing circuit means for calculating the output of each sensor is provided. The arithmetic processing circuit means Eu = eu Ev = [− ( eu + ew) + ev] / 2 The first position output E that has been processed and corrected so that Ew = [− (eu + ev) + ew] / 2.
u, a corrected second position output Ev, and a corrected third position output Ew are calculated, and the corrected position output is converted into a position signal by a zero-cross comparator.