CN101674043A - Method for controlling vector frequency converter of rotor field-oriented speed sensor-less - Google Patents

Abstract

The invention provides a method for controlling a vector frequency converter of a rotor field-oriented speed sensor-less. The method comprises the following steps that: by adopting a rotor flux estimation model combining current with voltage, as well as a speed estimation method based on an induction motor mathematical model, a rotor flux position angle can be obtained and sent to a rotation transformation link; three-phase output two-phase currents ia and ib are detected by use of a Hall current sensor, and a third-phase current ic = -(ia+ib) is calculated so as to obtain a real-time output current signal, namely a current signal of a motor; the real-time signal is supplied to the calculation of vector control; torque current component and excitation current component are obtained from detected current through vector transformation; flux-voltage reference quantity and torque-voltage reference quantity are generated by a PI controller by utilizing current error produced by flux currentand torque current; and after rotation transformation, the flux-voltage reference quantity voltage after inverse transformation and the torque-voltage reference quantity voltage after inverse transformation of two-phase output voltage are worked out, wherein the response has good dynamic characteristics and steady precision.

Description

The control method of vector frequency converter of rotor field-oriented speed sensor-less

Technical field

The present invention relates to a kind of frequency converter, relate in particular to the control method of a kind of vector frequency converter of rotor field-oriented speed sensor-less (SY8000 type).

Background technology

What traditional universal frequency converter extensively adopted is the constant voltage and frequency ratio control mode, also claims V/F control, and it adopts open loop constant voltage and frequency ratio and low-frequency voltage compensation technique usually, is applicable to that blower fan, water pump etc. are to the less demanding occasion of governing system dynamic property.

Also have a kind of speed sensor vector frequency converter at present, adopt photoelectric code disk uniform velocity transducer to carry out rotating speed usually and detect, and the feedback tach signal.But, because the installation of velocity transducer brings some defectives to system, the cost of system is increased greatly, the code-disc price that precision is high more is also expensive more, there is the problem of concentricity in the installation of code-disc on motor shaft, and the improper precision that influence is tested the speed is installed, and makes the maintenance of motor bring certain difficulty, under rugged environment, the precision of code-disc work is subject to the influence of environment.

Summary of the invention

The technical issues that need to address of the present invention have provided a kind of control method of vector frequency converter of rotor field-oriented speed sensor-less, are intended to solve the above problems.

In order to solve the problems of the technologies described above, the present invention realizes by following steps:

Adopt rotor flux appraising model that electric current and voltage combines and, can get the rotor flux position angle, and deliver to the rotation transformation link based on the velocity estimation method of asynchronous machine Mathematical Modeling;

Detect biphase current ia, the ib that three-phase is exported with Hall current sensor, calculate third phase current i c=-(ia+ib), thereby obtain real-time output current signal, be the current signal of motor;

For calculation of vector control provides live signal;

Obtain torque current component iT and excitation current component iM by the electric current that records through transform vector, the current error that utilizes iMref-iM (flux current datum quantity-flux current), iTref-iT (torque current reference amount-torque current) to be produced produces VMref (magnetic flux voltage datum quantity), VTref (torque voltage reference amount) through the PI controller, through obtaining two-phase output voltage V Dref (voltage after the inverse transformation of magnetic flux voltage datum quantity), VQref (voltage after the inverse transformation of torque voltage reference amount) after the rotation transformation.

Compared with prior art, the invention has the beneficial effects as follows: response has good dynamic characteristic and stable state accuracy.

Description of drawings

Fig. 1 is a flow chart of the present invention;

Fig. 2 is a magnetic linkage position estimation illustraton of model;

Fig. 3 is the velocity estimation illustraton of model.

Embodiment

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

As seen from Figure 1: the present invention realizes by following steps:

1. adopt rotor flux appraising model that electric current and voltage combines and, can get the rotor flux position angle, and deliver to the rotation transformation link based on the velocity estimation method of asynchronous machine Mathematical Modeling;

2. detect biphase current ia, the ib of three-phase output with Hall current sensor, calculate third phase current i c=-(ia+ib), thereby obtain real-time output current signal, be the current signal of motor;

3. provide live signal for calculation of vector control;

4. obtain torque current component iT and excitation current component iM by the electric current that records through transform vector, the current error that utilizes iMref-iM (flux current datum quantity-flux current), iTref-iT (torque current reference amount-torque current) to be produced produces VMref (magnetic flux voltage datum quantity), VTref (torque voltage reference amount) through the PI controller, through obtaining two-phase output voltage V Dref (voltage after the inverse transformation of magnetic flux voltage datum quantity), VQref (voltage after the inverse transformation of torque voltage reference amount) after the rotation transformation;

In step 1: described rotor flux appraising model is:

${\mathrm{\ψ}}_D^{d,i}=\left(\frac{L_s{L}_r-L_m^2}{L_r}\right)i_d^d+\frac{L_m}{L_r}{\mathrm{\ψ}}_d^{d,i}$

${\mathrm{\ψ}}_Q^{d,i}=\left(\frac{L_s{L}_r-L_m^2}{L_r}\right)i_q^d+\frac{L_m}{L_r}{\mathrm{\ψ}}_q^{d,i}$

In the formula: Ls, Lr are respectively stator and rotor self-induction (H).

Described velocity estimation method is:

${\mathrm{\ω}}_r={\mathrm{\ω}}_s-\frac{1}{{\left({\mathrm{\ψ}}_r^d\right)}^2}\frac{L_m}{T_i}({\mathrm{\ψ}}_d^d{i}_Q^d-{\mathrm{\ψ}}_q^d{i}_D^d)$

In the formula: Wr, Ws are respectively rotor and stator magnetic linkage electrical degree;

The Tr rotor time constant;

Lr, Lm, Rr are respectively the rotor self-induction, magnetizing inductance and rotor resistance.

The M axle of regulation MT coordinate system is along the direction of rotor flux Ψ r among the present invention, and then the MT coordinate system is just along rotor field-oriented, and this moment, the voltage equation of asynchronous machine was:

$\left(\begin{array}{c}{u}_M\\ u_T\\ 0\\ 0\end{array}\right)=\left(\begin{array}{cccc}{R}_s+L_{s}P& {-\mathrm{\ω}}_s{L}_s& L_{m}P& {-\mathrm{\ω}}_s{L}_m\\ {\mathrm{\ω}}_s{L}_s& R_s+L_{s}P& {\mathrm{\ω}}_s{L}_m& L_{m}P\\ L_{m}P& 0& R_r+L_{r}P& 0\\ {\mathrm{\ω}}_f{L}_m& 0& {\mathrm{\ω}}_f{L}_r& R_r+L_{r}P\end{array}\right)\left(\begin{array}{c}{i}_M\\ i_T\\ i_m\\ i_t\end{array}\right)$

Because the M axle is consistent with the direction of rotor flux Ψ r, so Ψ r has only the component of M, i.e. Ψ m=Ψ r; And the T axle component of rotor flux is zero, i.e. Ψ t=0.So the magnetic linkage equation is:

$\left(\begin{array}{c}{\mathrm{\ψ}}_M\\ {\mathrm{\ψ}}_T\\ {\mathrm{\ψ}}_m\\ 0\end{array}\right)=\left(\begin{array}{cccc}{L}_s& 0& L_m& 0\\ 0& L_s& 0& L_m\\ L_m& 0& L_r& 0\\ 0& L_m& 0& L_r\end{array}\right)\left(\begin{array}{c}{i}_M\\ i_T\\ i_m\\ i_t\end{array}\right)$

The torque equation that obtains after computing is:

$T_e=p_n\frac{L_m}{L_r}{\mathrm{\ψ}}_r{i}_T$

By following formula as seen, Control current iT just can control the electromagnetic torque Te of motor, thereby regulates rotating speed of motor.The rotor flux equation is:

${\mathrm{\&psi;}}_r={\mathrm{\&psi;}}_m=L_m\frac{i_{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="A2008100427320010H1.png"\; state="\{\{state\}\}">M</figure-callout>}}}{1+T_{r}P}$

By following formula as seen, regulate current i M and just can regulate Ψ r, when iM kept invariable, Ψ r just remained unchanged.

The estimation of the rotor flux position among the present invention:

In the asynchronous machine control system of rotor field-oriented Speedless sensor, the rotor flux estimation is a vital ring.If the advantage that the rotor flux estimation is inaccurate, then rotor field-oriented realizes that promptly the decoupling zero control of torque and magnetic flux can't realize.According to the fundamental equation of asynchronous machine under the two-phase rotating coordinate system, can obtain current mode rotor flux appraising model.

${\mathrm{\&psi;}}_D^{d,i}=\left(\frac{L_s{L}_r-L_m^2}{L_r}\right)i_d^d+\frac{L_m}{L_r}{\mathrm{\&psi;}}_d^{d,i}$

${\mathrm{\&psi;}}_Q^{d,i}=\left(\frac{L_s{L}_r-L_m^2}{L_r}\right)i_q^d+\frac{L_m}{L_r}{\mathrm{\&psi;}}_q^{d,i}$

The stator magnetic linkage of voltage model method is to carry out integration by the electromotive force that rotor flux is inducted to obtain:

${\mathrm{\&psi;}}_D^{d,v}=\&Integral;(u_D^d-i_D^d{R}_s-u_{\mathrm{comp},D})\mathrm{dt}$

${\mathrm{\&psi;}}_Q^{d,v}=\&Integral;(u_Q^d-i_Q^d{R}_s-u_{\mathrm{comp},Q})\mathrm{dt}$

Bucking voltage ucomp, D, ucomp, Q regulate by PI and calculate.

When low frequency, the stator voltage value diminishes, and the deviation of stator resistance pressure drop increases the influence of integral result, therefore must accurately detect stator resistance, but stator resistance can vary with temperature, and very to detect exactly is the comparison difficulty.And for current model, motor is at high-speed cruising, because the deviation of the parameter of motor causes the magnetic flux vibration easily.So native system combines these two kinds of methods, to remedy the deficiency of high and low frequency mutually.Its computing block diagram as shown in Figure 2.

The estimation of the rotating speed among the present invention:

Fundamental equation according to asynchronous machine under the two-phase rest frame can obtain the turn count model.Parameter of electric machine value is also most important in this model, otherwise occurs steady-state error easily.Model equation is:

${\mathrm{\&omega;}}_r={\mathrm{\&omega;}}_s-\frac{1}{{\left({\mathrm{\&psi;}}_r^d\right)}^2}\frac{L_m}{T_r}({\mathrm{\&psi;}}_d^d{i}_Q^d-{\mathrm{\&psi;}}_q^d{i}_D^d)$

The velocity estimation model framework chart as shown in Figure 3.

Claims (2)

1. the control method of a vector frequency converter of rotor field-oriented speed sensor-less, realize by following steps:

(1). adopt rotor flux appraising model that electric current and voltage combines and, can get the rotor flux position angle, and deliver to the rotation transformation link based on the velocity estimation method of asynchronous machine Mathematical Modeling;

(2). detect biphase current ia, the ib that three-phase is exported with Hall current sensor, calculate third phase current i c=-(ia+ib), thereby obtain real-time output current signal, be the current signal of motor;

(3). for calculation of vector control provides live signal;

(4). obtain torque current component and excitation current component by the electric current that records through transform vector, utilize flux current, current error that torque current produced to produce magnetic flux voltage datum quantity, torque voltage reference amount, through obtaining after the inverse transformation of two-phase output voltage magnetic flux voltage datum quantity voltage after voltage, the inverse transformation of torque voltage reference amount after the rotation transformation through the PI controller.

2. method according to claim 1, wherein: in step (1): described rotor flux appraising model is:

${\mathrm{\&psi;}}_D^{d,i}=\left(\frac{L_s{L}_r-L_m^2}{L_r}\right)i_d^d+\frac{L_m}{L_r}{\mathrm{\&psi;}}_d^{d,i}$

${\mathrm{\&psi;}}_Q^{d,i}=\left(\frac{L_s{L}_r-L_m^2}{L_r}\right)i_q^d+\frac{L_m}{L_r}{\mathrm{\&psi;}}_q^{d,i}$

In the formula: Ls, Lr are respectively stator and rotor self-induction (H).

Described velocity estimation method is:

${\mathrm{\&omega;}}_r={\mathrm{\&omega;}}_s-\frac{1}{{\left({\mathrm{\&psi;}}_r^d\right)}^2}\frac{L_m}{{\mathrm{\&tau;}}_r}({\mathrm{\&psi;}}_d^d{i}_Q^d-{\mathrm{\&psi;}}_q^d{i}_D^d)$

In the formula: Wr, Ws are respectively rotor and stator magnetic linkage electrical degree;

The Tr rotor time constant;

Lr, Lm, Rr are respectively the rotor self-induction, magnetizing inductance and rotor resistance.

Images