CN107404271B - A kind of non-synchronous motor parameter online recognition system and method - Google Patents

Abstract

The invention provides an asynchronous motor parameter online identification system and method, the system includes a voltage acquisition unit, a current acquisition unit, a rotational speed acquisition unit, a timer unit, an A/D sampling unit, a data storage unit and a parameter calculation unit, the voltage The acquisition unit collects the phase voltage of the motor and converts it into +5~-5V; the current acquisition unit collects the line current of the motor and converts it into +5~-5V; the speed acquisition unit passes the encoder Convert the mechanical speed of the motor into a digital signal; the timing unit sends a request to the A/D sampling unit and the data storage unit at regular intervals; after receiving the request signal from the timer, the A/D sampling unit will The input analog signal is converted into a digital signal; after the data storage unit receives the command sent by the timing unit, it reads and stores the digital signal output by the A/D sampling unit and the rotational speed sampling unit; the parameter calculation unit uses the data storage unit The online identification of asynchronous motor parameters is completed.

Description

A system and method for online identification of asynchronous motor parameters

Technical field:

The invention relates to the technical field of motor control, in particular to an asynchronous motor parameter online identification system and method.

Background technique:

Since the concept of vector control was proposed, the identification of asynchronous motor parameters has been a hot spot of concern. With the continuous improvement of the manufacturing technology and performance of the microcontroller, the motor control performance has a wider room for improvement. The performance of the current vector control strategy or direct torque control strategy for driving asynchronous motors directly depends on the accuracy of the motor parameters.

At present, the commonly used parameter identification algorithms for asynchronous motors are mostly parameter estimations of the motor in a static state or offline state. However, the actual motor parameters, especially the motor self-inductance and rotor resistance, will be affected by temperature, air humidity and electromagnetic The influence of a series of environmental factors such as the environment. During the operation of the actual motor, its parameters often change compared with the parameters estimated off-line. If the parameters used in the motor control algorithm remain unchanged, then the best performance of the motor cannot be exerted.

Therefore, when the motor is running, online parameter estimation of the motor parameters will be of great significance for improving the performance of the motor.

Invention content:

The technical problem to be solved by the present invention is to provide an asynchronous motor parameter online identification system and method for the current problem that the frequency converter with vector control function cannot perform online parameter identification.

The solution of the present invention to solve the problems of the technologies described above is,

An asynchronous motor parameter online identification system, comprising a voltage acquisition unit, a current acquisition unit, a rotational speed acquisition unit, an A/D sampling unit, a timer unit, a data storage unit and a parameter calculation unit, the timer unit, the data storage unit and The parameter calculation unit constitutes a micro-controller; the voltage acquisition unit collects the input phase voltage of the asynchronous motor and converts it into +5~-5V voltage that the A/D sampling unit can accept through the voltage Hall sensor; the current acquisition unit Collect the input line current of the asynchronous motor, and convert it into +5~-5V voltage that can be accepted by the A/D sampling unit through the Hall current sensor; the speed acquisition unit converts the steady-state mechanical speed of the asynchronous motor through the encoder It is a digital signal, which is directly sent to the microcontroller; the timing unit sends a request command to the A/D sampling unit and the data storage unit at regular intervals; after receiving the request signal of the timing unit, the A/D sampling unit , the analog output of the voltage acquisition unit and the current acquisition unit is converted into a 16-bit binary number, and after the timing unit sends a request signal, the converted output is sent to the microcontroller; the data storage unit is receiving After receiving the request signal sent by the timing unit, read and store the digital signals output by the A/D sampling unit and the rotational speed sampling unit; the parameter calculation unit calculates the data in the data storage unit to complete the online estimation of the parameters of the asynchronous motor.

The online identification method of the asynchronous motor parameter online identification system, the specific steps are as follows:

Step 1, data collection and processing:

The timing unit controls the A/D sampling unit to convert the voltage signal output by the voltage acquisition unit and the voltage signal output by the current acquisition unit after every fixed time T, and stores the data read from the A/D sampling unit in The data storage unit stores the mechanical speed of the motor measured by the speed acquisition unit in the data storage unit;

The three-phase line currents _ia , _ib and _ic collected by the current acquisition unit are converted by 3/2 to obtain the stator currents of the α-axis and β-axis of the asynchronous motor in the two-phase stationary coordinate system and

The three-phase phase voltages u _a , u _b and u _c collected by the voltage acquisition unit are converted by 3/2 to obtain the stator voltages of the α-axis and β-axis of the asynchronous motor in the two-phase stationary coordinate system and

Change the mechanical angular velocity ω of the motor sampled by the rotational speed acquisition unit into the electrical angular velocity of the motor:

ω _r = ω·p (3)

ω _r is the electrical angular velocity of the motor, p is the number of pole pairs of the motor;

Step 2, the convergence rate of the intermediate parameters The calculation of:

The finite time parameter identification equation of the asynchronous motor is shown in equation (4);

in the equation and Represent the stator currents of the α-axis and β-axis of the asynchronous motor in the two-phase stationary coordinate system, and Represent the stator voltages of the α-axis and β-axis of the asynchronous motor in the two-phase stationary coordinate system, ω _r is the electrical angular velocity of the motor, and k ₁ k ₂ k ₃ k ₄ k ₅ are the five coefficients of the intermediate parameter θ;

Record the intermediate parameter θ as:

Write down the matrix Γ ^T (t) as:

Remember the matrix y(t) as:

Equation (4) is expressed as:

y(t)=ΓT( ^t )θ (8)

The discrete form of equation (8) is:

y(N)= ^ΓT (N)θ (9)

N here is the number of iterations, which is equal to the number of times step 1 is executed and also equal to the number of data samples; where: the asynchronous motor α-axis and β-axis in the two-phase stationary coordinate system in the matrix y(N) and Γ ^T (N) stator current The stator voltages of the α-axis and β-axis of the asynchronous motor in the two-phase stationary coordinate system in the matrix Γ ^T (N) The electrical angular velocity ω _r of the motor in the matrix y(N) and Γ ^T (N) is the three-phase line current, three-phase phase voltage and motor mechanical speed obtained through the Nth sampling, which are respectively passed through the formula (1)(2 )(3); N is 1 when the algorithm is carried out for the first time;

According to the sampling voltage, sampling current, sampling speed of the Nth time and the estimated value of the intermediate parameters obtained at the N-1th time Find the convergence rate of the intermediate parameters for the Nth time As shown in formula (10):

where operator for:

Among them: A represents any column vector, A(n) represents any rational number, K is a 5th-order diagonal gain matrix, γ∈[0,1), and sign(a) is a sign function;

Step 3, new intermediate parameter estimates The calculation of:

According to the convergence rate of change of the intermediate parameters obtained in the Nth iteration and the estimated value of the intermediate parameters obtained for the N-1th time Calculate the estimated value of the intermediate parameter of the Nth iteration according to (12)

T represents the sampling time interval sent by the timing unit;

Step 4, judge whether the estimated intermediate parameters converge:

Repeat steps 1 to 3 until the estimated time exceeds When the algorithm performs parameter estimation, the minimum time for the estimated intermediate parameter θ to converge Such as formula (13):

in: is the estimated value of the intermediate parameter used by the parameter θ in step 3 for the first time and the error of the real intermediate parameters, λ _min (K) is the minimum eigenvalue of the gain matrix K, is the γ+1 power of the smallest singular value of the matrix Γ ^T (t), γ∈[0,1);

When the condition of (14) is met, it is considered that the estimated value of the intermediate parameter obtained at this time is It is the end of the actual intermediate parameter iteration;

If the formula (14) is not established, assign a new value to the number of iterations N according to (15) and return to step 1;

N=N+1 (15)

Step five, calculation of asynchronous motor parameters:

Estimated values of intermediate parameters using estimates Find the parameters of the asynchronous motor, and obtain the estimated value of the intermediate parameters Such as (16):

Using the five coefficients of the intermediate parameter obtain the estimated value of the parameters of the asynchronous motor;

Estimation of the stator resistance of an asynchronous motor

Estimated value of stator self-inductance and an estimate of the rotor self-inductance

Estimated value of rotor resistance By substituting (18) into (19) to obtain:

Estimated value of motor mutual inductance Obtained by (20):

Step 6: Judgment of parameter correction conditions:

If the ratio K1 of the motor mutual inductance and the motor rotor self-inductance can be accurately obtained through other parameter estimation methods, as shown in (21), then perform step 7; where L _m and L _r represent the actual mutual inductance of the motor and the actual rotor self-inductance sense,; if the coefficient K1 cannot be known, then the algorithm ends in step six;

L _m =K1·L _r (21)

Step seven, further correction of the estimated value of the motor parameters:

The estimated value of the motor mutual inductance calculated in step 5 Correct it with formula (22) to get its new estimated value L' _m :

according to:

Find the five new coefficients k ₁ 'k' ₂ k ₃ 'k' ₄ k ₅ ' of the intermediate parameters, and use this as the initial value of the new iteration As shown in (23), make N=1, and return to step 1 to continue the estimation of the intermediate parameter θ;

When n=1 is carried out to step 7 for the first time, step 7 is carried out every time thereafter, n adds 1, until satisfying the condition of (24) formula expression, algorithm finishes;

|L _r (n)-L _r (n-1)|≤0.00001 (24)

Wherein: L _r (n) and L _r (n-1) represent the self-inductance of the motor rotor obtained from the nth and n-1th executions to step 6 respectively, and L _r (0)=0.

Compared with the prior art, the present invention has the following advantages:

1. The present invention detects the online status of the motor during steady-state operation including: input phase voltage, input line current, and actual rotational speed of the motor. Using these measured values, the stator resistance, motor mutual inductance, and motor constant speed of the asynchronous motor can be identified online. These four parameters are rotor self-inductance and motor rotor resistance.

2. This method is derived based on Lyapunov stability, and the gain matrix K used in iterations remains unchanged, so the calculation steps are less than the commonly used iterative least squares method or Kalman filter algorithm.

3. This algorithm can be used in a limited time The parameters of the asynchronous motor are estimated internally. This feature can make the resource allocation of the microcontroller more compact when designing the algorithm, and improve the resource utilization of the microcontroller.

Description of drawings:

Fig. 1 is a block diagram of the parameter online identification system of the present invention.

Fig. 2 is a flow chart of the identification algorithm of the finite time parameters of the asynchronous motor under the condition that the ratio of mutual inductance and self-inductance is unknown.

Fig. 3 is a flow chart of the online identification algorithm of asynchronous motor parameters under the condition that the ratio of mutual inductance and self-inductance is known.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the present invention is described in further detail:

When the asynchronous motor is running in a steady state, the voltage acquisition unit collects the input phase voltage of the motor and converts it into +5~-5V voltage acceptable to the A/D sampling unit through the voltage Hall sensor; the current acquisition unit collects the input line voltage of the motor The current is collected and converted into +5~-5V voltage acceptable to the A/D sampling unit through the Hall current sensor; the speed acquisition unit converts the steady-state asynchronous motor mechanical speed into a digital signal through the encoder, and sends it directly to the micro The controller; the timing unit sends a request command to the A/D sampling unit and the data storage unit at regular intervals; the A/D sampling unit outputs the voltage acquisition unit and the current acquisition unit after receiving the request signal from the timing unit The analog quantity is converted into a 16-bit binary number, and after the timing unit sends a request signal, the converted output is sent to the microcontroller; after the data storage unit receives the request signal sent by the timing unit, it reads and The digital signal output by the A/D sampling unit and the speed sampling unit is stored; the parameter calculation unit calculates the data in the data storage unit to complete the online estimation of the parameters of the asynchronous motor.

The specific execution steps of the parameter calculation unit:

Based on the characteristic that the ratio of mutual inductance and self-inductance of asynchronous motors does not change greatly with changes in physical conditions, the method of the present invention can be divided into parameter estimation under the condition of unknown mutual inductance and self-inductance ratio and mutual inductance and self-inductance combined with other off-line parameter identification methods. There are two schemes for correcting parameter estimation under the condition of known self-inductance ratio.

Scheme 1: The flow chart of the execution steps of the asynchronous motor finite-time parameter identification algorithm under the condition of unknown mutual inductance and self-inductance ratio is shown in Figure 2, and the specific steps are as follows:

(1) The initial value of the given intermediate parameter and a suitable fifth-order gain matrix K

(2) According to the Nth group of voltage values, current values and mechanical speed of the motor obtained by sampling and the intermediate parameters estimated by N-1 times To calculate the convergence rate of the intermediate parameters at this moment

Among them, Γ ^T (N) and y (N) such as (25) (26), γ∈[0,1)

The stator currents of the α-axis and β-axis of the asynchronous motor in the two-phase stationary coordinate system here Stator voltage of asynchronous motor α-axis and β-axis in two-phase stationary coordinate system The electrical angular velocity ω _r of the motor is obtained by the three-phase line current, the three-phase phase voltage and the mechanical speed of the motor obtained through the Nth sampling through formula (1)(2)(3).

(3) According to the convergence rate of intermediate parameters obtained in step (2) and the intermediate parameters of the N-1th estimate Find an estimate of the new intermediate parameter θ T represents the actual time interval of sampling points.

(4) Judging the estimated intermediate parameters according to the number of operations N of the sampled data and the sampling time interval T Whether it has converged, if (14) is satisfied, then execute step (5), otherwise assign N to N+1, and return to step (2)

in: is the intermediate parameter used by parameter θ in step 3 for the first time and the error of the real intermediate parameters, λ _min (K) is the minimum eigenvalue of the gain matrix K, is the γ+1 power of the smallest singular value of the matrix Γ ^T (t), γ∈[0,1).

(5) According to the estimated convergent intermediate parameters As shown in (16).

Using the five coefficients of the intermediate parameter Estimates of the parameters of the electric machine may be obtained.

Estimation of the motor's stator resistance

Estimated value of stator self-inductance and an estimate of the rotor self-inductance

Estimated value of rotor resistance By substituting (18) into (19) to obtain:

Estimated value of motor mutual inductance Obtained by (20):

Solution 2: If the ratio K1 of the mutual inductance of the motor and the self-inductance of the motor rotor can be accurately obtained through other methods, such as off-line parameter calculation method, iterative minimum quadratic generation, etc., combined with this condition, the flow of the execution steps of asynchronous motor parameter estimation As shown in Figure 3, the specific execution steps are as follows:

(1) The initial value of the given intermediate parameter Appropriate gain matrix K and the ratio K1 of mutual inductance and self-inductance obtained by other off-line parameter identification methods;

(2) According to the Nth group of voltage values, current values and mechanical speed of the motor obtained by sampling and the intermediate parameters estimated by N-1 times To calculate the convergence rate of the intermediate parameters at this moment

Among them, Γ ^T (N) and y (N) such as (25) (26), γ∈[0,1)

The stator currents of the α-axis and β-axis of the asynchronous motor in the two-phase stationary coordinate system here Stator voltage of asynchronous motor α-axis and β-axis in two-phase stationary coordinate system The electrical angular velocity ω _r of the motor is obtained from the three-phase line current, the three-phase phase voltage and the mechanical speed of the motor obtained by the Nth sampling through formula (1)(2)(3).

(3) According to the convergence rate of intermediate parameters obtained in step (2) and the intermediate parameters of the N-1th estimate Find an estimate of the new intermediate parameter θ T represents the actual time interval of sampling points.

(4) Judging whether the estimated value of the intermediate parameter θ converges according to the number of operations N of the sampled data and the sampling time interval T, if (14) is satisfied, then perform step (5), otherwise assign N as N+1, and return to step (2).

in: is the intermediate parameter used by parameter θ in step 3 for the first time and the error of the real intermediate parameters, λ _min (K) is the minimum eigenvalue of the gain matrix K, is the γ+1 power of the smallest singular value of the matrix Γ ^T (t), γ∈[0,1).

(5) According to the estimated convergent intermediate parameters As shown in (16).

Using the five coefficients of the intermediate parameter Estimates of the parameters of the electric machine may be obtained.

Estimation of the motor's stator resistance

Estimated value of stator self-inductance and an estimate of the rotor self-inductance

Estimated value of rotor resistance By substituting (18) into (19) to obtain:

Estimated value of motor mutual inductance Obtained by (20):

(6) The estimated value of the obtained motor mutual inductance Estimated value of motor rotor self-inductance obtained by using Amend with formula (22);

according to:

Find the five new coefficients k ₁ 'k' ₂ k ₃ 'k' ₄ k ₅ ' of the modified intermediate parameters, and use this as the initial value of the new iteration As shown in (23), let N=1, and return to step 1 to continue estimating the intermediate parameter θ.

When step 7 is executed for the first time, n=1, and then one is added to n each time step 7 is executed. The algorithm ends when the condition expressed in (24) is met.

|L _r (n)-L _r (n-1)|≤0.00001 (24)

Here, L _r (n) and L _r (n-1) represent the self-inductance of the motor rotor obtained from the nth and n-1th executions to step 6, respectively, and L _r (0)=0.

Claims (1)

1. a kind of online recognition method of non-synchronous motor parameter online recognition system, the system comprises voltage acquisition units, electricity Acquisition unit, revolving speed acquisition unit, A/D sampling unit, timer unit, data storage cell and parameter calculation unit are flowed, The timer unit, data storage cell and parameter calculation unit constitute microcontroller；The voltage acquisition unit will be different The input phase voltage of step motor, which is acquired and passes through voltage hall sensor, is converted to A/D sampling unit acceptable+5 ~-5V voltage；The input line current of asynchronous machine is acquired by the current acquisition unit, and passes through Hall current sensor Be converted to acceptable+5~-5V voltage of A/D sampling unit；The revolving speed acquisition unit passes through encoder for the asynchronous of stable state Electromechanics revolving speed is converted into digital signal, is transmitted directly to microcontroller；The timing unit is adopted every the set time to A/D Sample unit and data storage cell send a request command；The A/D sampling unit is in the request letter for receiving timing unit After number, the analog quantity that voltage acquisition unit and current acquisition unit export is converted, is converted to 16 bits, and After timing unit sends request signal, the output of conversion is sent to microcontroller；The data storage cell is receiving meter After the request signal that Shi Danyuan is sent, the digital signal of A/D sampling unit and the output of revolving speed sampling unit is read and stored；It is described Parameter calculation unit calculates the data in data storage cell, completes the On-line Estimation of non-synchronous motor parameter；

It is characterized by: specific step is as follows for the online recognition method:

Step 1, the acquisition and processing of data:

The timing unit after set time T, voltage signal that control A/D sampling unit export voltage acquisition unit with The voltage signal of current acquisition unit output is converted, and the data read from A/D sampling unit are stored in data storage Unit, while the electromechanics revolving speed that revolving speed acquisition unit measures is stored in data storage cell；

The three-phase line current i that current acquisition unit is collected_a、i_bAnd i_cBy 3/2 transformation, it is obtained in the static seat of two-phase The stator current of asynchronous machine α axis and β axis under mark systemWith

The three-phase phase voltage u that voltage acquisition unit is collected_a、u_bAnd u_cBy 3/2 transformation, it is obtained in the static seat of two-phase The stator voltage of asynchronous machine α axis and β axis under mark systemWith

The electromechanics angular velocity omega that revolving speed acquisition unit samples is become to the angular rate of motor:

ω_r=ω p (3)

ω_rIt is the angular rate of motor, p is the number of pole-pairs of motor；

Step 2, the rate of convergence of intermediate parametersCalculating:

Shown in the finite time parameter identification equation of asynchronous machine such as equation (4)；

In equationWithThe stator current of the asynchronous machine α axis and β axis under two-phase stationary coordinate system is respectively indicated,WithRespectively indicate the stator voltage of the asynchronous machine α axis and β axis under two-phase stationary coordinate system, ω_rIt is the angular rate of motor, k₁ k₂ k₃ k₄ k₅It is five coefficients of intermediate parameters θ；

Remember intermediate parameters θ are as follows:

Remember matrix Γ^T(t) are as follows:

Remember matrix y (t) are as follows:

Equation (4) then indicates are as follows:

Y (t)=Γ^T(t)θ (8)

The discrete form of equation (8) are as follows:

Y (N)=Γ^T(N)θ (9)

Here N is the number of iterations, equal to the sampling number that the number that step 1 executes is also equal to data；Wherein: matrix y (N) And Γ^T(N) stator current of asynchronous machine α axis and β axis under the two-phase stationary coordinate system inMatrix Γ^T(N) in Two-phase stationary coordinate system under asynchronous machine α axis and β axis stator voltageMatrix y (N) and Γ^T(N) electricity in Electromechanical angular velocity omega_r, it is the three-phase line current sampled by n-th, three-phase phase voltage and electromechanics revolving speed, difference It is acquired by formula (1) (2) (3)；N is 1 when algorithm carries out for the first time；

According to the sampled voltage of n-th, sample rate current, sampling revolving speed and the intermediate parameters estimated value acquired for the N-1 timesIt asks The intermediate parameters rate of convergence of n-th outAs shown in (10) formula:

Wherein operatorAre as follows:

Wherein: A indicates any column vector, and A (n) indicates any rational, and K is the diagonal gain matrix of 5 ranks, γ ∈ [0, 1), sign (a) is sign function；

Step 3, new intermediate parameters estimated valueCalculating:

Change rate is restrained according to the intermediate parameters that iv-th iteration acquiresThe intermediate parameters estimated value acquired with the N-1 timesThe estimated value of the intermediate parameters of iv-th iteration is calculated according to (12) formula

T indicates to count the sampling time interval that the timing unit is sent；

Step 4, judges whether the intermediate parameters estimated restrain:

Step 1 is repeated to step 3, until estimating that the time used is more thanWhen algorithm carries out parameter Estimation, estimated The convergent minimum time of intermediate parameters θ of meterSuch as (13) formula:

Wherein:It is the estimated value for the intermediate parameters that parameter θ is used when first time carrying out step 3With true centre The error of parameter, λ_min(K) be gain matrix K minimal eigenvalue,It is matrix Γ^T(t) γ of minimum singular value+1 time Side, γ ∈ [0,1)；

When the condition of (14) formula meets, it is believed that the estimated value of the intermediate parameters acquired at this timeIt is exactly actual centre Parameter iteration terminates；

New value and return step one are assigned to the number of iterations N according to (15) if (14) formula is invalid；

N=N+1 (15)

Step 5, the calculating of non-synchronous motor parameter:

Utilize the estimated value for the intermediate parameters that estimation obtainsNon-synchronous motor parameter is sought, the estimation of the intermediate parameters acquired ValueSuch as (16):

Utilize five coefficients of intermediate parametersAcquire the estimated value of the parameter of asynchronous machine；

The estimated value of the stator resistance of asynchronous machine

The estimated value of stator self inductanceWith the estimated value of rotor self-induction

The estimated value of rotor resistanceIt is acquired by the way that (18) are updated to (19) formula:

The estimated value of motor mutual inductanceIt is acquired by (20):

Step 6, the judgement of parameters revision condition:

If can accurately obtain the ratio K1 of motor mutual inductance and rotor self-induction by other method for parameter estimation, such as (21) shown in, seven are thened follow the steps；Here L_mAnd L_rIndicate the practical mutual inductance and actual rotor self-induction of motor；If can not learn This COEFFICIENT K 1, then algorithm to step 6 terminates；

L_m=K1L_r (21)

Step 7, the further amendment of parameter of electric machine estimated value:

By the calculated motor mutual inductance estimated value of step 5It is modified with (22) formula, obtains its new estimated value L '_m:

According to:

Find out five new coefficient ks of intermediate parameters '₁ k′₂ k′₃ k′₄ k′₅, as new iterative initial valueSuch as (23) It is shown, N=1 is enabled, and return step one continues the estimation of intermediate parameters θ；

N=1 when going to step 7 for the first time, hereafter step 7 of every execution, n add one, until satisfaction (24) formula indicates Condition when, algorithm terminates；

|L_r(n)-L_r(n-1)|≤0.00001 (24)

Wherein: L_r(n) and L_r(n-1) the rotor self-induction for respectively indicating n-th and being acquired when going to step 6 (n-1)th time, Enable L_r(0)=0.