CN102589405A - Motor rotor displacement measurement method - Google Patents

Abstract

A method for measuring the displacement of a motor mover. The method is to arrange two magnetic induction intensity sensors on the mover along the moving direction of the mover. The two sensors are separated by a quarter of the magnetic field pole distance, and the sampling signals of the two sensors are passed through the The processing circuit quantifies and normalizes the amplitude, then performs n times of frequency multiplication, and then performs zero-crossing detection to generate a group of orthogonal pulse signals, detect the pulse number of the pulse signal, and the phase difference of the group of orthogonal pulse signals . The present invention directly subdivides the magnetic field pitch τ into

Realize high-precision motor mover displacement measurement. The invention can solve the problems of complex calculation method, inconvenient hardware installation and high cost of the measuring device brought about by the requirement of high precision in motor mover displacement measurement.

Description

A method for measuring the displacement of a motor mover

technical field

The invention relates to a method for measuring the displacement of a mover in a motor with a sinusoidal magnetic field model, such as a moving-coil linear motor and a rotating motor, in particular to a long-stroke subdivision measurement algorithm.

Background technique

Precision dynamic measurement technology is an important link to realize dynamic precision control. In conventional application fields, sensors such as grating scales, laser interferometers, and magnetic scale scales are used as measurement methods for linear and angular displacements of moving coil linear motors and rotating motors. Patent 200720002447.8 describes the use of a grating position detection encoder for position detection, and patent 200610033455 describes the use of a grating encoder for real-time position feedback for positioning. These sensors need to arrange magnetic fields, grids and other devices that specially generate displacement signal characteristics on the motor stator, and arrange electronic processing unit devices that receive displacement signal characteristics on the mover; or arrange special devices that generate displacement signal characteristics on the mover, and An electronic processing unit arrangement is arranged on the stator. The special device for generating the displacement signal characteristic and the electronic processing unit device increase the structural complexity of the sensor system. In addition, although these sensors have high measurement accuracy, they require relatively complex circuits and optical devices and are expensive. In the actual motion process, if the Hall sensor is directly used for position measurement, there will be noise in the measurement signal itself and the sampling process, resulting in loss of measurement accuracy.

For an object like a motor, its magnetic field itself is an important way to detect the displacement signal. If the magnetic field information of the motor itself can be used to achieve high-precision displacement measurement, the complexity of sensor installation and signal can be reduced. Similar to the patent ZL201010034274.4, complex nonlinear equations need to be solved, which brings difficulties to industrial real-time applications; the measurement results of other similar patent description methods require a high signal-to-noise ratio for the measurement signal itself, which poses a challenge to the implementation circuit. Noise and other high requirements. Therefore, a measurement method that can not only reduce the complexity of sensor installation and signal, but also achieve high precision, insensitivity to original signal quality, and simple and fast signal processing urgently needs to be proposed.

Contents of the invention

The purpose of the present invention is to provide a method for measuring the displacement of the motor mover, which uses the magnetic field information of the motor itself to realize the high-precision displacement measurement of the motor mover, without special conversion algorithm, and can directly output the commonly used orthogonal coding signals in the field of industrial control.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

1) In the sinusoidal magnetic field formed by the motor stator magnetic steel array, two magnetic induction sensors are arranged on the mover along the moving direction of the mover: a sine sensor and a cosine sensor, and the distance between the sine sensor and the cosine sensor is τ/4, and the τ is the magnetic field pole pitch of the sinusoidal magnetic field of the motor, the sampling signal of the sine sensor is quantified by the signal processing circuit and the amplitude normalization process is performed to obtain the sine measurement signal S ₀ , the sampling signal of the cosine sensor is passed through the signal The processing circuit quantifies and normalizes the amplitude to obtain the cosine measurement signal C ₀ ;

2) by the signal processing circuit (8), the sine measurement signal S ₀ and the cosine measurement signal C ₀ are used for n times frequency multiplication operation, i.e. 2 ⁿ subdivision operations:

S ₁ =2*S ₀ *C ₀ , C ₁ =C ₀ *C ₀ -S ₀ *S ₀ ,

S ₂ =2*S ₁ *C ₁ , C ₂ =C ₁ *C ₁ −S ₁ *S ₁ ,

...,

S _n =2*S _n-1 *C _n-1 , C _n =C _n-1 *C _n-1 -S _n-1 *S _n-1

Obtain sine subdivision signal S _n and cosine subdivision signal C _n , wherein: S ₁ , C ₁ , S ₂ , C ₂ ... S _n-1 and C _n-1 are intermediate variables, n=1, 2, 3,...;

3) Perform zero-crossing detection on the sine subdivision signal _Sn and cosine subdivision signal _Cn obtained after n times of iterative calculation in step 2), and generate a group of orthogonal measurement pulse signals: sine measurement pulse signal A and Cosine measurement pulse signal B; if the sine subdivision signal S _n >0, the sine measurement pulse signal A outputs a high level; if the sine subdivision signal S _n <0, the sine measurement pulse signal A outputs Low level; if the cosine subdivision signal C _n >0, the cosine measurement pulse signal B outputs a high level; if the cosine subdivision signal C _n <0, the cosine measurement pulse signal B outputs a low level flat;

n＝1，2，3，...，正弦测量脉冲信号A的相位落后于余弦测量脉冲信号B的相位表示正向位移，正弦测量脉冲信号A的相位落提前于余弦测量脉冲信号B的相位表示反向位移，从而实现电机动子的位移测量。4) Detect the pulse number of the sine measurement pulse signal A or the cosine measurement pulse signal B, and the phase difference between the sine measurement pulse signal A and the cosine measurement pulse signal B, the sine measurement pulse signal A or the cosine measurement pulse signal B One pulse represents a displacement resolution of

n=1, 2, 3,..., the phase of the sine measurement pulse signal A lags behind the phase of the cosine measurement pulse signal B, indicating a positive displacement, and the phase of the sine measurement pulse signal A falls ahead of the phase of the cosine measurement pulse signal B Indicates the reverse displacement, so as to realize the displacement measurement of the motor mover.

将逐步变小。In the above-mentioned technical scheme, after n times of frequency multiplication operations, n=1, 2, 3, ..., the period of the sine subdivision signal S _n and the cosine subdivision signal C _n is With the increase of frequency multiplication operation times n, the cycle

will gradually become smaller.

The present invention is characterized in that, in step 2), the determining method of frequency multiplication number of times n is as follows:

Suppose B _M is the magnetic induction intensity amplitude of the sinusoidal magnetic field formed by the stator magnetic steel array of the motor, v _x is the sensor measurement noise, and the noise level is In order to ensure that the zero-crossing point can be detected smoothly, the maximum number of multiplication operations n is

The times n of frequency multiplication operations in step 2) of the present invention are different, and different subdivision measurements can be realized.

Adopting the above technical scheme can make the present invention achieve beneficial effects, that is, it does not need to arrange a special device for generating displacement signal characteristics, and directly uses the sinusoidal magnetic field information of the motor stator, which reduces the structural complexity of the sensor system, and because the algorithm only involves simple calculations, it is easier Obtaining fast measurements without the need for expensive electronic processing circuits and optics reduces costs, guaranteeing high precision mover displacement measurements while ensuring detection of said zero crossings.

Description of drawings

FIG. 1 is a schematic diagram of the overall structure of a mover displacement measuring device using a moving coil linear motor as an example in the present invention.

2a, 2b, 2c, and 2d are schematic diagrams of the sine-cosine measurement signal, the sine-cosine subdivision signal, and the sine-cosine measurement pulse signal respectively taking frequency multiplication operations n=4 and n=8 as examples in the present invention.

3a and 3b are schematic diagrams of sine and cosine measurement pulse signals in the working process of the present invention taking two different cases of mover displacement as examples.

Among them, 1-stator; 2-magnetic steel array; 3-sine sensor; 4-cosine sensor; 5-coil; 6-mover; 7-signal line; 8-signal processing circuit.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a schematic diagram of the installation structure of the sensor in the moving element displacement measurement method using a moving coil linear motor as an example in the present invention, including a moving coil linear motor, a sine sensor 3, a cosine sensor 4 and a signal processing circuit 8, the moving coil The type linear motor includes a stator 1 provided with a magnetic steel array 2 and a mover 6 provided with a coil 5 matched with it, and the signal processing circuit 8 is connected with the sine sensor 3 and the cosine sensor 4 through the signal line 7 .

A method for measuring the displacement of a motor mover provided by the invention comprises the following steps:

1) In the sinusoidal magnetic field formed by the magnetic steel array of the motor stator 1, two magnetic induction sensors are arranged on the mover 6 along the moving direction of the mover: a sine sensor 3 and a cosine sensor 4, and the sine sensor and the cosine sensor are separated by τ/4 , the τ is the magnetic field pole pitch of the sinusoidal magnetic field of the motor, the sampling signal of the sine sensor is quantified by the signal processing circuit 8 and the amplitude normalization process is performed to obtain the sine measurement signal S ₀ , the sampling signal of the cosine sensor is After the signal is quantized by the signal processing circuit 8 and subjected to amplitude normalization processing, a cosine measurement signal C ₀ is obtained;

2) by said signal processing circuit 8, said sine measurement signal S ₀ and cosine measurement signal C ₀ are done n times frequency multiplication operation:

S ₁ =2*S ₀ *C ₀ , C ₁ =C ₀ *C ₀ -S ₀ *S ₀ ,

S ₂ =2*S ₁ *C ₁ , C ₂ =C ₁ *C ₁ −S ₁ *S ₁ ,

...,

S _n =2*S _n-1 *C _n-1 , C _n =C _n-1 *C _n-1 -S _n-1 *S _n-1

Obtain sine subdivision signal S _n and cosine subdivision signal C _n , wherein: S ₁ , C ₁ , S ₂ , C ₂ ... S _n-1 and C _n-1 are intermediate variables, n=1, 2, 3,...;

3) Carry out zero-crossing detection on the sine subdivision signal S _n and the cosine subdivision signal C _n to generate a group of orthogonal measurement pulse signals: sine measurement pulse signal A and cosine measurement pulse signal B; the sine subdivision signal If S _n >0, the sine measurement pulse signal A outputs a high level; if the sine subdivision signal S _n <0, the sine measurement pulse signal A outputs a low level; the cosine subdivision signal C _n >0, the cosine measurement pulse signal B outputs a high level; the cosine subdivision signal C _n <0, then the cosine measurement pulse signal B outputs a low level;

n＝1，2，3，...，所述正弦测量脉冲信号A的相位落后于所述余弦测量脉冲信号B的相位表示正向位移，所述正弦测量脉冲信号A的相位提前于所述余弦测量脉冲信号B的相位表示反向位移，从而实现电机动子的位移测量。4) Detect the pulse number of the sine measurement pulse signal A or the cosine measurement pulse signal B, and the phase difference between the sine measurement pulse signal A and the cosine measurement pulse signal B, the sine measurement pulse signal A or the cosine measurement pulse signal One pulse of pulse signal B represents one displacement resolution

n=1, 2, 3,..., the phase of the sine measurement pulse signal A lagging behind the phase of the cosine measurement pulse signal B indicates positive displacement, and the phase of the sine measurement pulse signal A is ahead of the phase of the cosine measurement pulse signal B The phase of the cosine measurement pulse signal B represents the reverse displacement, thereby realizing the displacement measurement of the motor mover.

随着倍频运算次数n的增大，所述周期

将逐步变小。After n times of frequency multiplication operations, the period of the sine subdivision signal S _n and the cosine subdivision signal C _n is

With the increase of frequency multiplication operation times n, the cycle

will gradually become smaller.

The method for determining the number of frequency multiplication operations n is as follows:

为保证能够顺利检测过零点，最大的空间倍频运算次数n为 $n=[{\log }_2\left(\frac{B_M}{v_x}\right)-3].$ Suppose B _M is the magnetic induction intensity amplitude of the sinusoidal magnetic field formed by the stator magnetic steel array of the motor, v _x is the sensor measurement noise, and the noise level is

In order to ensure that the zero-crossing point can be detected smoothly, the maximum number of spatial frequency multiplication operations n is $\mathrm{no}=[{\log }_2\left(\frac{B_m}{v_x}\right)-3].$

The times n of frequency doubling operations are different, and different subdivision measurements can be realized.

Example:

Referring to Figures 1 and 3, the displacement measurement process of the mover 6 is demonstrated for a better understanding of the present invention.

根据最大倍频运算次数计算公式计算n＝8。The pole distance of the magnetic field is τ=35.35mm, and the distance between the sine sensor and the cosine sensor is τ/4, that is, 8.8375mm. Using 12-bit AD sampling, the noise level

Calculate n=8 according to the calculation formula of the maximum number of multiplication operations.

1) According to the above calculation, in the sinusoidal magnetic field formed by the stator magnetic steel array 2 of the moving coil linear motor, two magnetic induction sensors are arranged on the mover along the moving direction of the mover: the sine sensor 3 and the cosine sensor 4, the τ It is the magnetic field pole distance of the sinusoidal magnetic field of the motor, and the distance between the sine sensor 3 and the cosine sensor 4 is τ/4, which is 8.8375 mm. Obtain the sine measurement signal S ₀ , quantify the sampled signal of the cosine sensor 4 through the signal processing circuit (8) and perform amplitude normalization processing to obtain the cosine measurement signal C ₀ ;

2) by the signal processing circuit 8, the sine measurement signal S ₀ and the cosine measurement signal C ₀ are n times, that is, 8 frequency multiplication operations, that is, ²⁸ subdivision operations:

S ₁ =2*S ₀ *C ₀ , C ₁ =C ₀ *C ₀ -S ₀ *S ₀ ,

S ₂ =2*S ₁ *C ₁ , C ₂ =C ₁ *C ₁ −S ₁ *S ₁ ,

S ₃ =2*S ₂ *C ₂ , C ₃ =C ₂ *C ₂ −S ₂ *S ₂ ,

S ₄ =2*S ₃ *C ₃ , C ₄ =C ₃ *C ₃ −S ₃ *S ₃ ,

S ₅ =2*S ₄ *C ₄ , C ₅ =C ₄ *C ₄ −S ₄ *S ₄ ,

S ₆ =2*S ₅ *C ₅ , C ₆ =C ₅ *C ₅ −S ₅ *S ₅ ,

S ₇ =2*S ₆ *C ₆ , C ₇ =C ₆ *C ₆ −S ₆ *S ₆ ,

S ₈ =2*S ₇ *C ₇ , C ₈ =C ₇ *C ₇ −S ₇ *S ₇

Sine subdivision signal S ₈ and cosine subdivision signal C ₈ are obtained, among which: S ₁ , C ₁ , S ₂ , C ₂ , S ₃ , C 3 , S ₄ , C ₄ , S ₅ , C ₅ , S _{6 ,} C ₆ , S ₇ and C ₇ are intermediate variables;

3) With reference to Figures 2c and 2d, Figures 2c and 2d are schematic diagrams of the sine measurement signal, sine subdivision signal, sine measurement pulse signal and cosine measurement signal, cosine subdivision signal, and cosine measurement pulse respectively taking n=8 as an example The schematic diagram of the signal, the sine subdivision signal S ₈ and the cosine subdivision signal C ₈ obtained after n times or 8 iterative calculations in step 2) are subjected to zero-crossing detection to generate a group of orthogonal measurement pulse signals: sine measurement pulse Signal A and cosine measurement pulse signal B; if the sine subdivision signal S ₈ >0, the sine measurement pulse signal A outputs a high level, and the sine subdivision signal S ₈ <0, then the sine measurement pulse signal A outputs a low level If the cosine subdivision signal C ₈ >0, the cosine measurement pulse signal B outputs a high level, and if the cosine subdivision signal C ₈ <0, then the cosine measurement pulse signal B outputs a low level.

4) With reference to Figures 3a and 3b, Figure 3a detects that the number of pulses of the sinusoidal measurement pulse signal A at time t is 3 from time 0, representing The displacement length of the sine measurement pulse signal A lags behind the phase of the cosine measurement pulse signal B, indicating a positive displacement, so Figure 3a shows that the displacement at time t relative to time 0 is +0.4143mm; Figure 3b detects the cosine measurement pulse at time t The number of pulses of signal B is 4 from time 0, representing The displacement length of the sine measurement pulse signal A is ahead of the phase of the cosine measurement pulse signal B to indicate the reverse displacement, so Figure 3b shows that the displacement at time t relative to time 0 is -0.5523mm.

Through the above steps, the sinusoidal magnetic field information of the motor itself is directly used to reduce the complexity of the system, the hardware installation is convenient, the calculation method is simple and fast, and high-cost optical devices are not required, which saves costs. Ensure the realization of high-resolution motor mover displacement measurement.

Claims (2)

1. A method for measuring displacement of an electric mover, characterized in that the method comprises: 1) In the sinusoidal magnetic field formed by the magnetic steel array of the motor stator (1), two magnetic induction sensors are arranged on the mover (6) along the moving direction of the mover: a sine sensor (3) and a cosine sensor (4). The distance between the sensor and the cosine sensor is τ/4, and the τ is the magnetic field pole distance of the sinusoidal magnetic field of the motor. The sampling signal of the sinusoidal sensor is quantified by the signal processing circuit (8) and the amplitude normalization process is performed to obtain the sinusoidal measurement signal S ₀ , quantizing the sampled signal of the cosine sensor through the signal processing circuit (8) and performing amplitude normalization processing to obtain a cosine measurement signal C ₀ ; 2) by said signal processing circuit (8) said sine measurement signal S ₀ and cosine measurement signal C ₀ are done n times frequency multiplication operation: S ₁ =2*S ₀ *C ₀ , C ₁ =C ₀ *C ₀ -S ₀ *S ₀ , S ₂ =2*S ₁ *C ₁ , C ₂ =C ₁ *C ₁ −S ₁ *S ₁ , ..., S _n =2*S _n-1 *C _n-1 , C _n =C _n-1 *C _n-1 -S _n-1 *S _n-1 Obtain sine subdivision signal S _n and cosine subdivision signal C _n , wherein: S ₁ , C ₁ , S ₂ , C ₂ ... S _n-1 and C _n-1 are intermediate variables, n=1, 2, 3,...; 3) Carry out zero-crossing detection to described sine subdivision signal S _n and cosine subdivision signal C _n , generate a group of orthogonal measurement pulse signals: sine measurement pulse signal A and cosine measurement pulse signal B; described sine subdivision signal If S _n >0, the sine measurement pulse signal A outputs a high level; if the sine subdivision signal S _n <0, the sine measurement pulse signal A outputs a low level; the cosine subdivision signal C _n >0, the cosine measurement pulse signal B outputs a high level; the cosine subdivision signal C _n <0, then the cosine measurement pulse signal B outputs a low level; 4) Detect the pulse number of the sine measurement pulse signal A or the cosine measurement pulse signal B, and the phase difference between the sine measurement pulse signal A and the cosine measurement pulse signal B, the sine measurement pulse signal A or the cosine measurement pulse signal One pulse of pulse signal B represents one displacement resolution

n=1, 2, 3,..., the phase of the sine measurement pulse signal A lagging behind the phase of the cosine measurement pulse signal B indicates positive displacement, and the phase of the sine measurement pulse signal A is ahead of the phase of the cosine measurement pulse signal B The phase of the cosine measurement pulse signal B represents the reverse displacement, thereby realizing the displacement measurement of the motor mover. 2. a kind of motor mover displacement measuring method according to claim 1, is characterized in that, step 2) in the determination method of frequency multiplication operation times n as follows: Suppose B _M is the magnetic induction intensity amplitude of the sinusoidal magnetic field formed by the stator magnetic steel array of the motor, v _x is the sensor measurement noise, and the noise level is

In order to ensure that the zero-crossing point can be detected smoothly, the maximum number of multiplication operations n is

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