CN110212818B

CN110212818B - Angle detection method for permanent magnet motor

Info

Publication number: CN110212818B
Application number: CN201910622786.3A
Authority: CN
Inventors: 余张国; 秦鸣悦; 黄强; 陈学超; 孟立波; 黄岩
Original assignee: Beijing Institute of Technology BIT
Current assignee: Beijing Institute of Technology BIT
Priority date: 2019-07-11
Filing date: 2019-07-11
Publication date: 2020-10-27
Anticipated expiration: 2039-07-11
Also published as: CN110212818A

Abstract

The invention discloses a permanent magnet motor angle detection method, which comprises the following steps: three-phase analog signals are output through 3 linear Hall sensors uniformly distributed on the periphery of the motor

Processing three-phase analog signals to obtain sine waves H with a fixed phase difference of 120 degrees_n(n-1, 2,3), the sine waveform H_n(n is 1,2,3) and obtaining square waves sec (2), sec (1) and sec (0) with the phase difference of 120 degrees after comparison; the method comprises the steps of utilizing a counter to count edges of square waves sec (2), sec (1) and sec (0), and calculating the current position of the motor according to the counting of the counter.

Description

Angle detection method for permanent magnet motor

Technical Field

The invention belongs to the technical field of motor detection, and particularly relates to a permanent magnet motor angle detection method.

Background

The current motor motion control needs the detection of the position of a rotor, and the linear Hall sensor has the advantages of small volume, low cost and the like, and can replace a high-precision encoder to realize the angle detection of the permanent magnet motor. The prior art provides an absolute coding technology based on linear hall, a certain section of hall signals are extracted through section division to carry out position detection, however, the linearity of the extracted signals is poor, and arcsin and arctan inverse trigonometric functions need to be calculated. However, most of the existing linear hall-based position detection needs to calculate an inverse trigonometric function, which results in calculation consumption in memory and time delay.

Disclosure of Invention

In order to solve the defects in the prior art, the method for detecting the angle of the permanent magnet motor is provided, and the Hall signal wave band with better linearity is extracted through more reasonable section division and is approximately processed as a straight line, so that the calculation of an inverse trigonometric function is avoided, and unnecessary calculation consumption is reduced.

The technical scheme adopted by the invention is as follows:

a permanent magnet motor angle detection method comprises the following steps: three-phase analog signals are output through 3 linear Hall sensors uniformly distributed on the periphery of the motor

Processing three-phase analog signals to obtain sine waves H with a fixed phase difference of 120 degrees_n(n-1, 2,3), the sine waveform H_n(n is 1,2,3) and obtaining square waves sec (2), sec (1) and sec (0) with the phase difference of 120 degrees after comparison; the edges of the square waves sec (2), sec (1) and sec (0) are counted by a counter respectively, and the current position of the motor is calculated according to the counting sum of the counter, and the calculation is expressed as follows:

wherein, cnt2, cnt1, and cnt0 are respectively the counters counting the edges of square waves sec (2), sec (1), and sec (0).

Further, by

Processing the three-phase analog signals to obtain sine waves with a fixed phase difference of 120 degrees;

further, the three-phase analog signal

Expressed as:

wherein A is_nAnd D_nAnd (n is 1,2 and 3) is the amplitude gain and the direct current component of the nth Hall signal respectively.

Further, the sine wave H_n(n ═ 1,2,3) is represented by:

the invention has the beneficial effects that:

according to the method, the approximate straight line of the waveform segment with good linearity is extracted for processing through a more reasonable section division mode, so that the inverse trigonometric function calculation is avoided, and the calculation consumption is reduced.

Drawings

FIG. 1 is a linear Hall sensor layout diagram;

FIG. 2 is a schematic diagram of position detection based on normalized Hall signals;

fig. 3 is a timing diagram of sector transition detection.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in figure 1, 3 linear Hall sensors are uniformly distributed around a motor with a 120-degree phase difference, and three-phase analog signals are output

As raw static hall signals:

where θ is the angular displacement of the rotor relative to the Hall sensor, A_nAnd D_nThe (n-1, 2 and 3) is the amplitude gain and the direct current component of the nth hall signal, which are easy to be obtained by measurement, and then the original static hall signal has amplitude error and direct current error.

By:

a sinusoidal waveform with a fixed phase difference of 120 degrees that can be approximated as ideal is obtained, with the expression:

wherein N is the normalized amplitude gain;

the normalized Hall signal based position detection mechanism, as shown in FIG. 2, once three Hall sensor signals H are collected₁， H₂And H₃The comparator outputs sec (2), sec (1) and sec (0), and sec (2), sec (1) and sec (0) are 3 square waves with a phase difference of 120 degrees, the electrical angle of 360 degrees is roughly divided into six segments each containing 60 electrical angles, edges of sec (2), sec (1) and sec (0) are counted by a counter 2, a counter 1 and a counter 0, respectively, as shown in fig. 3, and thus a change in the segment to which the rotor position belongs is detected, and the direction is determined. The sum of counter 2, counter 1 and counter 0 is then the total number of sectors rotated by the rotor position. Thus, when the rotor jumps from one sector to the preceding sector, the count is increased by 1 and vice versa. And after the 60-degree section of the current position is obtained, extracting a wave band of which each section is in the middle size to perform accurate position calculation. The thick lines in fig. 3 extract the mid-position band for each sector. Because the waveform linearity of the section of-30 degrees to 30 degrees is good, the section can be processed approximately as a line segment under the appropriate precision requirement. The calculation expression of the current position of the motor is as follows:

where θ is the detected motor angle and H is the intermediate magnitude hall signal extracted for each sector.

The above embodiments are only used for illustrating the design idea and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and implement the present invention accordingly, and the protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes and modifications made in accordance with the principles and concepts disclosed herein are intended to be included within the scope of the present invention.

Claims

1. The angle detection method of the permanent magnet motor is characterized in that three-phase analog signals are output by 3 linear Hall sensors uniformly distributed on the periphery of the motor

Processing three-phase analog signals to obtain sine waves H with a fixed phase difference of 120 degrees_nN is 1,2,3, the sine waveform H_nN is 1,2,3, and square waves sec (2), sec (1) and sec (0) with a phase difference of 120 degrees are obtained after comparison; counting the edges of square waves sec (2), sec (1) and sec (0) by using a counter respectively, further detecting that the section to which the rotor position belongs changes, and determining the direction at the same time; after the 60-degree section where the current position is located is obtained, extracting a wave band of which each section is in the middle size to calculate the position, and calculating the current position of the motor according to the counting of the counter, wherein the calculation is represented as follows:

wherein, cnt2, cnt1, and cnt0 are respectively the edge counts of square wave sec (2), sec (1), and sec (0) by the counter, where θ is the detected motor angle, N is the normalized amplitude gain, and H is the middle-sized hall signal extracted for each segment.

2. The angle detection method of the permanent magnet motor according to claim 1, characterized by comprising the step of

Processing the three-phase analog signals to obtain sine waves with a fixed phase difference of 120 degrees, A_nAnd D_nThe amplitude gain and the direct current component of the nth Hall signal are respectively, and n is 1,2 and 3.

3. The method of claim 1, wherein the three-phase analog signal is used for detecting the angle of the permanent magnet motor

Expressed as:

wherein A is_nAnd D_nThe amplitude gain and the direct current component of the nth Hall signal are respectively, and n is 1,2 and 3.

4. The angle detection method of claim 1, wherein the sine wave H is_nExpressed as: