CN101783646A - Induction motor stator resistance and temperature parameter identifying method - Google Patents

Abstract

The invention relates to an induction motor stator resistance and temperature parameter identifying method. A control method based on model reference self-adaption is used for identifying the induction motor stator resistance and the stator winding temperature. According to the calculating method of an asynchronous motor rotor magnetic chain, the current magnetic chain calculating model is used as a reference model, a voltage magnetic chain calculating model is used as an adjusting model, and the output difference between the two models is used for continuously adjusting the stator resistance parameter in the voltage model through the self-adaption rate until the output difference of the two models is zero. The invention can effectively identify the stator resistance parameter and the stator winding temperature of the asynchronous motor in running, enhance the low-frequency property of the direct torque frequency-variable speed adjusting system of the asynchronous motor, eliminate the use of the temperature sensor, and save the cost of the speed adjusting system.

Description

Induction motor stator resistance and temperature parameter identifying method

Technical field

The present invention relates to a kind of method of testing, particularly a kind of induction motor stator resistance and temperature parameter identifying method.

Background technology

At present, variable-frequency control technique is owing to have good speed adjusting performance and good characteristics of energy saving, widespread adoption just gradually.The high performance variable frequency speed regulation technology can be by rotor field-oriented, stator flux orientation, and the air-gap field orientation is classified.And these governing systems all will be subjected to the influence of the parameter of electric machine, are very important as the accurate estimation of stator magnetic linkage in the stator flux orientation technology, when adopting following magnetic linkage computation model: ${\stackrel{.}{\mathrm{\ψ}}}_s=\∫({\stackrel{.}{U}}_s-{\stackrel{.}{I}}_s{R}_s)\mathrm{dt},$ System can be subjected to the influence of motor stator resistance parameter in the low cruise performance.Stator resistance can become big along with the rising of temperature in motor operation course.When resistance increased to a certain degree, the inaccurate whole system that very likely causes of the observation of stator magnetic linkage was collapsed.Simultaneously, the temperature sensor of settling in motor can increase system cost, has reduced system reliability.

Summary of the invention

The present invention be directed to the problem that the variation meeting of stator resistance under the present low speed exerts an influence to the frequency conversion speed-adjusting system by stator flux orientation, propose a kind of induction motor stator resistance and temperature parameter identifying method, provide a kind of model reference adaptive algorithm to come stator resistance is estimated and compensated the stator resistance pressure drop.The stator resistance that picks out is estimated asynchronous machine stator winding mean temperature by the temperature identification unit, can effectively improve by systematic function under the variable-frequency control technique low speed of stator flux orientation.

Technical scheme of the present invention is: a kind of induction motor stator resistance and temperature parameter identifying method comprise the steps:

1), when under the frequency-converting speed-governing control system of induction machine stator field orientation, moving, the stator side three-phase current that electric current, voltage sensor senses go out, voltage become electric current and voltage under two phase coordinate systems by 3/2 coordinate converter;

2), electric current calculates rotor flux with rotating speed by rotor magnetic linkage reference model then, simultaneously, the voltage and current after the conversion is regulated Model Calculation by rotor and is gone out rotor flux;

3), the difference of two models picks out stator resistance by PI control;

4), this stator resistance is added to direct Torque Control stator magnetic linkage computing unit respectively and temperature is distinguished model unit, but on-line identification goes out stator resistance, estimates asynchronous machine stator winding mean temperature.

Described rotor magnetic linkage reference model is a current model, and it is voltage model that rotor is regulated model.Described current model is as follows:

$P\left(\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{r\α}}\\ {\mathrm{\ψ}}_{\mathrm{r\β}}\end{array}\right)=\frac{1}{{\mathrm{\τ}}_r}(L_m\left(\begin{array}{c}{i}_{\mathrm{s\α}}\\ i_{\mathrm{s\β}}\end{array}\right)-\left(\begin{array}{cc}1& {\mathrm{\τ}}_r\mathrm{\ω}\\ -{\mathrm{\τ}}_r\mathrm{\ω}& 1\end{array}\right)\left(\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{r\α}}\\ {\mathrm{\ψ}}_{\mathrm{r\β}}\end{array}\right))$

Voltage model is as follows:

$\left(\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{r\α}}\\ {\mathrm{\ψ}}_{\mathrm{r\β}}\end{array}\right)=\frac{L_r}{L_m}(\left(\begin{array}{c}{\∫}_0^t(u_{\mathrm{s\α}}-R_s{i}_{\mathrm{s\α}})\mathrm{dt}\\ {\∫}_0^t(u_{\mathrm{s\β}}-R_s{i}_{\mathrm{s\β}})\mathrm{dt}\end{array}\right)-\left(\begin{array}{cc}\mathrm{\σ}{L}_s& 0\\ 0& \mathrm{\σ}{L}_s\end{array}\right)\left(\begin{array}{c}{i}_{\mathrm{s\α}}\\ i_{\mathrm{s\β}}\end{array}\right))$

In the formula: $\mathrm{\σ}=1-\frac{L_m^2}{L_s{L}_r}$ Be the total leakage inductance coefficient of motor; ${\mathrm{\τ}}_r=\frac{L_r}{R_r}$ Be rotor time constant; ψ _{R α}, ψ _{R β}Be α, the beta-axis component of rotor flux under the static orthogonal coordinates of two-phase; u _{S α}, i _{S α}, u _{S β}, i _{S β}Be stator voltage, α, the beta-axis component of electric current under the static orthogonal coordinates of two-phase; P, ω are respectively differential operator, rotor velocity; R _sBe stator resistance; L _s, L _r, L _mBe respectively motor stator self-induction, rotor self-induction, rotor mutual inductance.

Beneficial effect of the present invention is: induction motor stator resistance of the present invention and temperature parameter identifying method can effectively pick out asynchronous machine stator resistance and stator winding temperature, the use of having saved temperature sensor.By stator resistance is compensated, can effectively improve by systematic function under the variable-frequency control technique low speed of stator flux orientation.

Description of drawings

Fig. 1 is MRAS identification stator resistance structural map in induction motor stator resistance of the present invention and the temperature parameter identifying method;

Fig. 2 is induction motor stator resistance of the present invention and the application schematic diagram of temperature parameter identifying method in the Direct Torque frequency conversion speed-adjusting system;

Fig. 3 is the motor speed oscillogram after induction motor stator resistance of the present invention and the temperature parameter identifying method utilization;

Fig. 4 is the motor torque oscillogram after induction motor stator resistance of the present invention and the temperature parameter identifying method utilization.

Embodiment

Two kinds of computation models---the voltage model and the current model of rotor magnetic linkage.As the reference model, voltage model is as regulating model with current model.

Reference model is as follows:

$P\left(\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{r\α}}\\ {\mathrm{\ψ}}_{\mathrm{r\β}}\end{array}\right)=\frac{1}{{\mathrm{\τ}}_r}(L_m\left(\begin{array}{c}{i}_{\mathrm{s\α}}\\ i_{\mathrm{s\β}}\end{array}\right)-\left(\begin{array}{cc}1& {\mathrm{\τ}}_r\mathrm{\ω}\\ -{\mathrm{\τ}}_r\mathrm{\ω}& 1\end{array}\right)\left(\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{r\α}}\\ {\mathrm{\ψ}}_{\mathrm{r\β}}\end{array}\right))$

The adjusting model is as follows:

$\left(\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{r\α}}\\ {\mathrm{\ψ}}_{\mathrm{r\β}}\end{array}\right)=\frac{L_r}{L_m}(\left(\begin{array}{c}{\∫}_0^t(u_{\mathrm{s\α}}-R_s{i}_{\mathrm{s\α}})\mathrm{dt}\\ {\∫}_0^t(u_{\mathrm{s\β}}-R_s{i}_{\mathrm{s\β}})\mathrm{dt}\end{array}\right)-\left(\begin{array}{cc}\mathrm{\σ}{L}_s& 0\\ 0& \mathrm{\σ}{L}_s\end{array}\right)\left(\begin{array}{c}{i}_{\mathrm{s\α}}\\ i_{\mathrm{s\β}}\end{array}\right))$

In the following formula: $\mathrm{\σ}=1-\frac{L_m^2}{L_s{L}_r}$ Be the total leakage inductance coefficient of motor;

${\mathrm{\τ}}_r=\frac{L_r}{R_r}$ Be rotor time constant;

ψ _{R α}, ψ _{R β}Be α, the beta-axis component of rotor flux under the static orthogonal coordinates of two-phase;

u _{S α}, i _{S α}, u _{S β}, i _{S β}Be stator voltage, α, the beta-axis component of electric current under the static orthogonal coordinates of two-phase;

P, ω are respectively differential operator, rotor velocity;

R _sBe stator resistance;

L _s, L _r, L _mBe respectively motor stator self-induction, rotor self-induction, rotor mutual inductance.

When the output of above reference model and adjusting model is inconsistent, their difference is come stator resistance parameter in the regulation voltage model by certain adaptive rate, till the output of two models equates.The stator resistance value of this moment is the stator resistance numerical value of motor when this moment moving.Getting the proportional integral adaptive law is that Kp+Ki/s.Kp is a proportionality coefficient, and Ki is an integral coefficient, and 1/s represents integration.Obtain the stator resistance adaptive algorithm:

$\underset{\‾}{{\hat{R}}_S}=(K_p+\frac{K_i}{S}){\mathrm{\ϵ}}_{R_s}$

$\hat{t}=\frac{{\hat{R}}_S}{R_s}(234.5+t_0)-234.5$

In the formula: ${\mathrm{\ϵ}}_{R_s}=i_s\·({\mathrm{\ψ}}_r-{\widehat{\mathrm{\ψ}}}_r)=i_{\mathrm{s\α}}({\mathrm{\ψ}}_{\mathrm{r\α}}-{\widehat{\mathrm{\ψ}}}_{\mathrm{r\α}})+i_{\mathrm{s\β}}({\mathrm{\ψ}}_{\mathrm{r\β}}-{\widehat{\mathrm{\ψ}}}_{\mathrm{r\β}})$ Be stator resistance self adaptation state difference.

ψ _rWith

Represent reference model respectively and regulate model numerical value.

Be the stator resistance value that picks out.

Simultaneously, stator resistance is subjected to the motor windings Temperature Influence and changes, and relation is as follows between them:

${\mathrm{<figure-callout\; id="1"\; label="R\; s"\; filenames="DEST\_PATH\_H200910045573501E00021.png,DEST\_PATH\_HSB00000071034300011.png"\; state="\{\{state\}\}">R</figure-callout>}}_s=R_s\frac{234.5+t}{234.5+t_0}$

In the formula: R _sBe the residing room temperature t of motor ₀The time resistance value.

R _S1Resistance value when being t for temperature.

Can pick out mean temperature in stator winding this moment according to the resistance value that estimates thus:

$\hat{t}=\frac{{\hat{R}}_S}{R_s}(234.5+t_0)-234.5$

In the formula:

The mean temperature of estimation when moving for motor;

R _sBe room temperature t ₀Under resistance value, be normal value;

Be the stator resistance that picks out.

When concrete grammar comprised the steps: to move under the frequency-converting speed-governing control system of induction machine stator field orientation, the stator side three-phase current that sensor goes out, voltage became electric current and voltage under two phase coordinate systems by 3/2 coordinate converter.Electric current calculates rotor flux with rotating speed by the rotor flux reference model then.Simultaneously, the voltage and current after the conversion goes out rotor flux by rotor adjusting Model Calculation.The difference of two models picks out stator resistance by PI control, this stator resistance is added to direct Torque Control stator magnetic linkage computing unit and temperature identification model unit respectively, can on-line identification go out stator resistance, estimate asynchronous machine stator winding mean temperature, improve the direct Torque Control low-speed performance.

Below the present invention is described further.Fig. 1 is a MRAS identification stator resistance structural map.The input of current model has isa among Fig. 1, and isb represents the component of stator current under the two-phase orthogonal coordinate system respectively, and w represents the rotor angular velocity of rotation.Be output as the rotor flux value.Voltage model input has usa, usb to represent the component of stator voltage under the two-phase orthogonal coordinate system respectively, and Rs* represents the stator resistance that picks out.Output also is rotor flux.Both output picks out stator resistance by foregoing adaptive algorithm.

Fig. 2 is this invention application in the Direct Torque frequency conversion speed-adjusting system, and the Direct Torque frequency conversion speed-adjusting system is the high performance variable frequency speed regulation technology, and its control response is fast, and torque down at a high speed, rotating speed are highly stable.Direct Torque Control is made up of several sections such as coordinate transform, stator magnetic linkage calculating, stator magnetic linkage adjusting, torque adjustment, rotating speed PI adjusting, magnetic linkage interval judgement, switch list selection and pwm pulse generations among Fig. 2.Coordinate transform becomes motor stator end three-phase voltage, electric current into two-phase numerical value, rotating speed PI regulates according to the motor speed that feeds back in real time and calculates given torque, under the two-phase rest frame, calculate stator magnetic linkage and electromagnetic torque then, regulate and the torque adjustment module by stator magnetic linkage, and magnetic linkage interval judgement module, output switching signal is selected to switch list and the pwm pulse function produces suitable substance P WM pulse signal, thereby obtains correct motor stator end three-phase voltage.Guarantee that in real time motor stator magnetic linkage and torque can maintain about set-point.

Because under low speed, the stator magnetic linkage computing module is subjected to the variation of stator resistance and causes flux observation inaccurate, thereby influence the stability of system.

This invention is used for the Direct Torque system, as stator resistance identification and the compensating module among Fig. 2.Experimental result has been verified effectively, and performance when this method can improve direct Torque Control low speed can be used to carry out the temperature identification simultaneously.

Fig. 3 is the motor speed oscillogram after adopting this to invent.Because load increases suddenly in the 2s in system, thus among Fig. 3 in 2s rotating speed a shake is arranged, but return on the set-point again very soon, and very steady.Shown at low speed, can keep stabilization of speed equally under the dynamic load.

Fig. 4 is the motor torque oscillogram after adopting this to invent.Among Fig. 4 2s the time load increase suddenly, the load of following that the motor electromagnetic torque also can be very fast increases and increases, and keeps stable, has shown good dynamic characteristic.

Claims (3)

1. induction motor stator resistance and temperature parameter identifying method is characterized in that, comprise the steps:

1), when under the frequency-converting speed-governing control system of induction machine stator field orientation, moving, the stator side three-phase current that electric current, voltage sensor senses go out, voltage become electric current and voltage under two phase coordinate systems by 3/2 coordinate converter;

2), electric current calculates rotor flux with rotating speed by rotor magnetic linkage reference model then, simultaneously, the voltage and current after the conversion is regulated Model Calculation by rotor and is gone out rotor flux;

3), the difference of two models picks out stator resistance by PI control;

4), this stator resistance is added to direct Torque Control stator magnetic linkage computing unit and temperature identification model unit respectively, on-line identification goes out stator resistance, estimates asynchronous machine stator winding mean temperature.

2. according to described induction motor stator resistance of claim 1 and temperature parameter identifying method, it is characterized in that described rotor magnetic linkage reference model is a current model, it is voltage model that rotor is regulated model.

3. according to described induction motor stator resistance of claim 2 and temperature parameter identifying method, it is characterized in that described current model is as follows:

$P\left(\begin{array}{c}{\mathrm{\&psi;}}_{\mathrm{r\&alpha;}}\\ {\mathrm{\&psi;}}_{\mathrm{r\&beta;}}\end{array}\right)=\frac{1}{{\mathrm{\&tau;}}_r}(L_m\left(\begin{array}{c}{i}_{\mathrm{s\&alpha;}}\\ i_{\mathrm{s\&beta;}}\end{array}\right)-\left(\begin{array}{cc}1& {\mathrm{\&tau;}}_r\mathrm{\&omega;}\\ -{\mathrm{\&tau;}}_r\mathrm{\&omega;}& 1\end{array}\right)\left(\begin{array}{c}{\mathrm{\&psi;}}_{\mathrm{r\&alpha;}}\\ {\mathrm{\&psi;}}_{\mathrm{r\&beta;}}\end{array}\right))$

Voltage model is as follows:

$\left(\begin{array}{c}{\mathrm{\&psi;}}_{\mathrm{r\&alpha;}}\\ {\mathrm{\&psi;}}_{\mathrm{r\&beta;}}\end{array}\right)=\frac{L_r}{L_m}(\left(\begin{array}{c}{\&Integral;}_0^t(u_{\mathrm{s\&alpha;}}-R_s{i}_{\mathrm{s\&alpha;}})\mathrm{dt}\\ {\&Integral;}_0^t(u_{\mathrm{s\&beta;}}-R_s{i}_{\mathrm{s\&beta;}})\mathrm{dt}\end{array}\right)-\left(\begin{array}{cc}\mathrm{\&sigma;}{L}_s& 0\\ 0& \mathrm{\&sigma;}{L}_s\end{array}\right)\left(\begin{array}{c}{i}_{\mathrm{s\&alpha;}}\\ i_{\mathrm{s\&beta;}}\end{array}\right))$

In the formula: $\mathrm{\&sigma;}=1-\frac{L_m^2}{L_s{L}_r}$ Be the total leakage inductance coefficient of motor; ${\mathrm{\&tau;}}_r=\frac{L_r}{R_r}$ Be rotor time constant; ψ _{R α}, ψ _{R β}Be α, the beta-axis component of rotor flux under the static orthogonal coordinates of two-phase; u _{S α}, i _{S α}, u _{S β}, i _{S β}Be stator voltage, α, the beta-axis component of electric current under the static orthogonal coordinates of two-phase; P, ω are respectively differential operator, rotor velocity; R _sBe stator resistance; L _s, L _r, L _mBe respectively motor stator self-induction, rotor self-induction, rotor mutual inductance.

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