CN101425777B - Voltage orienting frequency conversion controller for open loop non-speed sensor - Google Patents

Abstract

The invention relates to a voltage orientation frequency-vary controller of an opening-ring no-speed sensor, and a controlling technology of a sensing motor, which overcomes the problems of the poor loaded capacity and the light loaded oscillation of a motor caused by the influences of the factors of the voltage decrease of a stator resistor, rotating difference frequencies, dead areas, and the like in the low-speed running of the traditional constant-voltage frequency-ratio control. The voltage orientation frequency-vary controller is composed of the following units, i.e. a current sensor, avector coordinate changing unit, a PI adjustor, a calculating unit of voltage boosting amount, a sliding-frequency calculating unit, a frequency adder, a first operation unit, a second operation unit, a third operation unit, a fourth operation unit, a fifth operation unit, a sixth operation unit and a SVPWM unit. The PI adjustor is used for controlling the no-power current, and the problem of thelight-loaded oscillation of the sensing motor is effectively inhibited. The product of the power current and the motor stator resistance is used as the voltage boosting in loading, the loaded capacity of the motor is obviously improved, and the low-speed performance of the motor is greatly improved.

Description

Voltage orienting frequency conversion controller for open loop non-speed sensor

Technical field

The present invention relates to a kind of Control of Induction Motors technology, be specifically related to controller a kind of Speedless sensor stator voltage vector oriented, that use constant voltage and frequency ratio (VVVF) control algolithm.

Background technology

Along with the continuous development and progress of industrial and agricultural production, people are more and more higher to the requirement of speed governing.Induction Motor Vector Control is carried out decoupling zero according to field orientation to current of electric according to the motor dynamic model, obtains torque current component and excitation current component, respectively it is controlled then.Can obtain very fast rotating speed response, and operation is very steady.But the performance of vector control and the accuracy of the parameter of electric machine have very big relation, need in actual applications the parameter of electric machine is carried out on-line identification, and control algolithm is very complicated.

Compare with vector control, constant voltage and frequency ratio control (Variable Voltage and VariableFrequency, VVVF) method have simply, reliably, low cost and other advantages, be widely used in the AC speed regulating field.But traditional constant voltage and frequency ratio control (VVVF) is when low cruise, owing to be subjected to the influence of factors such as stator resistance pressure drop, slip frequency and dead band, the motor carrying load ability is poor.But also there are problems such as underloading vibration.

Summary of the invention

The invention provides a kind of voltage orienting frequency conversion controller for open loop non-speed sensor, when being controlled at low cruise to overcome traditional constant voltage and frequency ratio, owing to be subjected to the influence of factors such as stator resistance pressure drop, slip frequency and dead band, the problem of motor carrying load ability difference and underloading vibration.

Controller of the present invention is by forming with lower unit:

Current sensor: to detect the phase current on the induction machine IM stator by current sensor 1;

Vector coordinate transform unit: to realize that the coordinate transform of induction machine IM stator voltage vector oriented is resolved into instantaneous active current i with detected stator current _dWith instantaneous reactive current i _q

Pi regulator: given reactive current i _q ^*With instantaneous reactive current i _qSubtract each other input, with the output voltage V of pi regulator as pi regulator _qAs the q shaft voltage specified rate of SVPWM unit, to utilize 3 couples of instantaneous reactive current i of pi regulator _qCarry out FEEDBACK CONTROL, thereby make the reactive current on the induction machine IM stator keep constant;

Voltage lifting capacity computing unit: utilize instantaneous active current i _dWith induction motor stator resistance R ₁The voltage lifting capacity V of product during as run with load _b

Slip-frequency computing unit: according to formula Calculate current slip-frequency f _s, L wherein _mBe the magnetizing inductance of induction machine, R ' ₂Rotor resistance for induction machine;

Frequency adder: according to frequency set-point f ^*With slip-frequency f _s, obtain current running frequency f ₁=f ^*+ f _s

An arithmetic element: according to voltage-frequency than V/f and current running frequency f ₁, according to formula V ₁=f ₁* V/f obtains reference output voltage V ₁

No. two arithmetic elements: according to reference output voltage V ₁Output voltage V with pi regulator _q, according to formula Obtain the base value V ' of d shaft voltage _d

No. three arithmetic elements: with the base value V ' of d shaft voltage _dWith voltage lifting capacity V _bSuperimposed, as the d shaft voltage specified rate V of SVPWM unit 12 _d, V _d=V ' _d+ V _b

No. four arithmetic elements: by to current running frequency f ₁Carry out integration and obtain the angle θ of stator voltage d axle component and fixed coordinates ₁

No. five arithmetic elements: according to formula

Obtain the angle theta between stator voltage vector and the d axle _V,

No. six arithmetic elements: with angle θ ₁And angle theta _VSuperpose, thereby obtain angle between stator voltage vector and the fixed coordinates, θ=θ ₁+ θ _V, this angle is the required stator voltage vector angle of coordinate transform in the vector coordinate transform unit;

SVPWM unit: according to d shaft voltage specified rate V _d, pi regulator output voltage V _qWith the pwm control signal of stator voltage vector angle θ output to inverter.

The present invention is based on the constant voltage and frequency ratio controller of the open loop non-speed sensor of stator voltage vector oriented, this controller is controlled the motor reactive current by introducing the PI current regulator, and keep it constant, and efficiently solving the problem of motor underloading vibration, motor operates steadily.And torque is promoted, thereby make induction machine when low speed, have very high output torque according to the product of active current and stator resistance.

Beneficial effect of the present invention is: owing to introduce pi regulator the induction machine reactive current is controlled, can make very fast the setting up in magnetic field of induction machine, and constant in whole operating frequency section maintenance, make and the permanent magnetic flux speed governing of motor can effectively suppress the phenomenon that the motor underloading is vibrated.Simultaneously, the voltage lifting capacity when carrying as band according to the product of active current and stator resistance can make the output torque of motor be greatly improved.

Application at some manufacturing machine equipment needs the low and frequency conversion speed-adjusting system of performance between common constant voltage and frequency ratio (VVVF) control and high-performance vector control or direct torque control of cost.Controller proposed by the invention has significantly improved the performance of controller on the basis that does not increase algorithm complexity.

Description of drawings

Fig. 1 is an electrical block diagram of the present invention; Fig. 2 is the asymmetric T type of an induction machine schematic equivalent circuit; Fig. 3 is that stator voltage, the current phasor of induction machine concerns schematic diagram; Fig. 4 is the unloaded motor current waveform figure that has used controller of the present invention; Fig. 5 is the full load starting motor current waveform figure that has used controller of the present invention; Fig. 6 has used controller of the present invention, fully loaded, the motor current waveform figure when 1.5Hz moves; Fig. 7 has used motor full-load run V controller of the present invention, 1.5Hz when operation _q, V _d, rotating speed and i _dWaveform contrast schematic diagram; Fig. 8 has used motor full-load current oscillogram controller of the present invention, 0.5Hz when operation; Motor full-load run V when Fig. 9 is the 0.5Hz operation _q, V _d, rotating speed and i _dWaveform contrast schematic diagram.

Embodiment

Embodiment one: specify present embodiment below in conjunction with Fig. 1 to Fig. 3.Controller of the present invention is by forming with lower unit;

Current sensor 1: to detect the phase current on the induction machine IM stator by current sensor 1;

Vector coordinate transform unit 2: to realize that the coordinate transform of induction machine IM stator voltage vector oriented is resolved into instantaneous active current i with detected stator current _dWith instantaneous reactive current i _q

Pi regulator 3: given reactive current i _q ^*With instantaneous reactive current i _qSubtract each other input, with the output voltage V of pi regulator as pi regulator 3 _qAs the q shaft voltage specified rate of SVPWM unit 12, to utilize 3 couples of instantaneous reactive current i of pi regulator _qCarry out FEEDBACK CONTROL, thereby make the reactive current on the induction machine IM stator keep constant;

Voltage lifting capacity computing unit 4: utilize instantaneous active current i _dWith induction motor stator resistance R ₁The voltage lifting capacity V of product during as run with load _b

Slip-frequency computing unit 5: according to formula Calculate current slip-frequency f _s, L wherein _mBe the magnetizing inductance of induction machine, R ' ₂Rotor resistance for induction machine;

Frequency adder 6: according to frequency set-point f ^*With slip-frequency f _s, obtain current running frequency f ₁=f ^*+ f _sFrequency set-point f ^*Needs according to operation are selected voluntarily by the user.

An arithmetic element 7: according to voltage-frequency than V/f and current running frequency f ₁, according to formula V ₁=f ₁* V/f obtains reference output voltage V ₁

No. two arithmetic elements 8: according to reference output voltage V ₁Output voltage V with pi regulator 3 _q, according to formula

Obtain the base value V ' of d shaft voltage _d

No. three arithmetic elements 9: with the base value V ' of d shaft voltage _dWith voltage lifting capacity V _bSuperimposed, as the d shaft voltage specified rate V of SVPWM unit 12 _d, V _d=V ' _d+ V _b

No. four arithmetic elements 10: by to current running frequency f ₁Carry out integration and obtain the angle θ of stator voltage d axle component and fixed coordinates ₁,

No. five arithmetic elements 11: according to formula

Obtain the angle theta between stator voltage vector and the d axle _V,

No. six arithmetic elements 13: with angle θ ₁And angle theta _VSuperpose, thereby obtain angle θ between stator voltage vector and the fixed coordinates, θ=θ ₁+ θ _V, this angle is the required stator voltage vector angle of coordinate transform in the vector coordinate transform unit 2;

SVPWM unit 12: according to d shaft voltage specified rate V _d, pi regulator output voltage V _qWith the pwm control signal of stator voltage vector angle θ output to inverter.

In conjunction with the accompanying drawings principle of the present invention, realization and effect being done one elaborates.The theory diagram of the voltage oriented controller of this improvement open loop non-speed sensor as shown in Figure 1.In circuit diagram shown in Figure 2, because motor stator leakage inductance L _{1 δ}Much smaller than magnetizing inductance L _m(L _{1 δ}＜＜L _m), therefore, can be similar to and think the active current I of motor from project angle _dThe main power output that produces motor; Reactive current is mainly set up the generation power of motor and is exported necessary magnetic field.So reactive current is constant can to keep the constant of motor magnetic flux when keeping, and realizes permanent magnetic flux speed governing.And the product according to active current and stator resistance comes output voltage is promoted, and can improve the output torque of motor low frequency.

At first, the output current by the current sensor senses frequency converter is input to coordinate transformation unit with measurement result.What sampling obtained is the threephase stator current i _U, i _VAnd i _WAlso can only detect two-phase wherein, be the zero third phase electric current that calculates by three-phase transient current sum.Then, according to stator voltage azimuth θ ₁Electric current to sampling carries out coordinate transform, and its transformation for mula is as follows:

$\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{i}_U\\ i_V\\ i_W\end{array}\right],$ With $\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]=\left[\begin{array}{cc}\cos \mathrm{\θ}& -\sin \mathrm{\θ}\\ \sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]---\left(1\right)$

Wherein, θ is the stator voltage azimuth, and its computing formula is:

θ＝θ ₁+θ _V

θ ₁＝∫2πf ₁dt (2)

${\mathrm{\θ}}_V=\mathrm{arctg}\frac{V_q}{V_d}$

By coordinate transform, stator current is resolved into active current component i _dWith reactive current component i _qThen, by pi regulator to reactive current i _qControl, and keep it constant.The reactive current set-point i of pi regulator _q ^*Be taken as 1/3 of motor rated current, the output of adjuster is as the set-point of q shaft voltage in the SVPWM unit, and its computing formula is as follows:

$V_q=K_p(i_q^{*}-i_q)+K_i\∫(i_q^{*}-i_q)\mathrm{dt}---\left(3\right)$

The stator current active current component i that coordinate transform is obtained _dWith stator resistance R ₁Multiply each other as the compensation rate V of voltage magnitude _b, its formula is as follows:

V _b＝i _dR ₁ (4)

According to the equivalent electric circuit of Fig. 2 motor as can be known, the voltage at magnetizing inductance two ends equates with the voltage at rotor resistance two ends.Therefore have:

$2\mathrm{\&pi;}{f}_1{L}_m{I}_q={\mathrm{<figure-callout\; id="2"\; label="I\; d\; R"\; filenames="H200810209654XE00011.png,H200810209654XE00032.png"\; state="\{\{state\}\}">I</figure-callout>}}_d\frac{R_{}^{}}{}\frac{{}_2^{\&prime;}}{s}---\left(5\right)$

Thus, can calculate slip-frequency according to the rotor resistance and the magnetizing inductance of active current and reactive current and motor, its formula is as follows:

$f_s=\frac{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="H200810209654XE00011.png,H200810209654XE00032.png"\; state="\{\{state\}\}">R</figure-callout>}}_2^{\&prime;}}{2\mathrm{\&pi;}{L}_m}\&CenterDot;\frac{I_d}{I_q}---\left(6\right)$

The slip-frequency that calculates is obtained current running frequency with the addition of frequency set-point, as follows:

f ₁＝f ^*+f _s (7)

According to voltage-frequency than V/f and current running frequency f ₁The reference output voltage V that produces ₁, its computing formula is as follows:

V ₁＝f ₁*V/f (8)

Then, according to reference output voltage V ₁Output voltage V with pi regulator _q, the following formula of foundation obtains the base value V ' of d shaft voltage _d

$V_d^{\&prime;}=\sqrt{{{\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="H200810209654XE00011.png,H200810209654XE00012.png"\; state="\{\{state\}\}">V</figure-callout>}}_1}^2-V_q^2}---\left(9\right)$

At last, with d shaft voltage base value V ' _dWith voltage magnitude compensation rate V _bStack is as the set-point V of the d shaft voltage in the SVPWM unit _d

V _d＝V′ _d+V _b (10)

The SVPWM unit is according to direct-axis voltage V _d, quadrature-axis voltage V _qAnd voltage vector angle θ, produce 6 road pwm signals, drive inverter, come motor is controlled.

Embodiment two: provide a specific embodiment below in conjunction with Fig. 4 to Fig. 9.This embodiment adopts controller of the present invention and an inverter and an induction machine, the parameter of this motor is as follows: rated voltage: 380V, rated current 15.4A, rated power is 7.5Kw, and rated speed is 1440r/min, and rated frequency is 50Hz, stator resistance is 0.611 Ω, rotor resistance is 0.434 Ω, and magnetizing inductance is 105.6mH, and the stator leakage inductance is 2.32mH.Current waveform when Fig. 4 is empty load of motor, current of electric is steady when as can be seen from the figure unloaded, does not have the phenomenon of vibration.Motor current waveform when Fig. 5 is full load starting, the load capacity of motor is strong as can be seen from Figure, and reaction is fast, has just reached the stable operation size of current at second cycle electric current.Motor current waveform when Fig. 6 moves for full load 1.5Hz.Active current when Fig. 7 is respectively 1.5Hz full-load run, motor speed, V _dOutput and V _qOutput waveform, the mean speed of 1.5Hz full load motor is 45.28rpm.Motor current waveform when Fig. 8 is 0.5Hz full-load run.Active current when Fig. 9 is respectively 0.5Hz full-load run, motor speed, V _dOutput and V _qOutput waveform, the mean speed of 0.5Hz full load motor is 18.75rpm.Adopt the low-speed performance of the inventive method motor to be significantly improved, motor can be fully loaded with stable operation when 0.5Hz.

Claims (1)

1. voltage orienting frequency conversion controller for open loop non-speed sensor is characterized in that it is by forming with lower unit:

Current sensor (1): to detect the phase current on induction machine (IM) stator by current sensor (1);

Vector coordinate transform unit (2): to realize that the coordinate transform of induction machine (IM) stator voltage vector oriented is resolved into instantaneous active current i with detected stator current _dWith instantaneous reactive current i _q

Pi regulator (3): given reactive current i _q ^*With instantaneous reactive current i _qSubtract each other input, with the output voltage V of pi regulator as pi regulator (3) _qAs the q shaft voltage specified rate of SVPWM unit (12), to utilize pi regulator (3) to instantaneous reactive current i _qCarry out FEEDBACK CONTROL, thereby make the reactive current on induction machine (IM) stator keep constant;

Voltage lifting capacity computing unit (4): utilize instantaneous active current i _dWith induction motor stator resistance R _iThe voltage lifting capacity V of product during as run with load _b

Slip-frequency computing unit (5): according to formula

Calculate current slip-frequency f _s, L wherein _mBe the magnetizing inductance of induction machine, R ' ₂Rotor resistance for induction machine;

Frequency adder (6): according to frequency set-point f ^*With slip-frequency f _s, obtain current running frequency f ₁=f ^*+ f _s

An arithmetic element (7): according to voltage-frequency than V/f and current running frequency f ₁, according to formula V ₁=f ₁* V/f obtains reference output voltage V ₁

No. two arithmetic elements (8): according to reference output voltage V ₁And the output voltage V of pi regulator (3) _q, according to formula

Obtain the base value V ' of d shaft voltage _d

No. three arithmetic elements (9): with the base value V ' of d shaft voltage _dWith voltage lifting capacity V _bSuperimposed, as the d shaft voltage specified rate V of SVPWM unit (12) _d, V _d=V ' _d+ V _b

No. four arithmetic elements (10): by to current running frequency f ₁Carry out integration and obtain the angle θ of stator voltage d axle component and fixed coordinates ₁,

No. five arithmetic elements (11): according to formula

Obtain the angle theta between stator voltage vector and the d axle _V,

No. six arithmetic elements (13): with angle θ ₁And angle theta _VSuperpose, thereby obtain angle θ between stator voltage vector and the fixed coordinates, θ=θ ₁+ θ _V, this angle is the required stator voltage vector angle of coordinate transform in the vector coordinate transform unit (2);

SVPWM unit (12): according to d shaft voltage specified rate V _d, pi regulator output voltage V _qWith the pwm control signal of stator voltage vector angle θ output to inverter.

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