CN103746631B - A kind of energy-saving control method of asynchronous machine - Google Patents

Abstract

An energy-saving control method for an asynchronous motor. The asynchronous motor is powered by an inverter and controlled by a speed regulator ^. The inverter includes a power module and a control module including a digital signal processor DSP; The difference between the actual angular velocity ω of the motor obtained is sent to the speed regulator, and the output of the speed regulator is the given electromagnetic torque T _e ^* of the motor; ω _s ^* is the optimal slip angular frequency of the asynchronous motor; The constant electromagnetic torque T _e ^* and the optimal slip angular frequency ω _s ^* are calculated to obtain the torque current component Isq of the motor in the two-phase rotating coordinate system; from the torque current component Isq and the optimal slip angular frequency ω _s ^* Obtain the excitation current component Isd of the asynchronous motor; according to the torque current component Isq and the excitation current component Isd of the stator current, respectively obtain the stator two-phase voltage Usd and Usq in the steady-state operation state; and then calculate the asynchronous motor through ipark The two-phase voltage components Usα and Usβ in the two-phase static coordinate system are then controlled by space vector pulse width modulation to control the inverter to realize the energy-saving control of the asynchronous motor.

Description

A kind of energy-saving control method of asynchronous motor

technical field

The invention relates to motor control technology, in particular to an energy-saving control method for an asynchronous motor.

Background technique

Asynchronous motors are the most widely used in various motors due to their simple structure and high reliability. Since the 1980s, their frequency conversion speed control systems have gradually gained popularity, and their energy-saving effect is remarkable in the speed control drives of fans and pumps. .

When the asynchronous motor powered by the inverter is running in a non-rated state, the efficiency is often lower than the rated operation, especially in the low-speed and light-load state, and the motor in actual operation often works in a light-load state, which is the so-called " This is an old problem encountered when the motor is running. The motor also encounters this problem after frequency conversion and speed regulation, especially when the load of the fan and water pump occupies a large proportion, it is particularly prominent when running at low speed. According to statistics, the power consumption of motors accounts for about 60% to 70% of the total industrial electricity consumption. In practical application, the overall operating conditions of motors in my country are far from those of foreign countries. The unit efficiency is about 75%, which is about 10% lower than that of foreign countries; the system operating efficiency is 30-40%, which is 20-30% lower than the international advanced level. . Therefore, the application of motors in our country has great energy-saving potential, and it is imperative to implement energy-saving motors. Energy-saving control of motors has become a research hotspot.

The energy-saving control of electric motors has been one of the hot issues studied by researchers since the application of frequency conversion speed regulation technology. However, so far, almost no energy-saving control strategy can be really applied to engineering. Kusko and Galler, Rowan and Lipo, and Daniel are pioneers in the energy-saving control operation of asynchronous motors. They studied the efficiency optimization problem of asynchronous motors based on a simple loss model. In essence, various efficiency optimization control strategies of asynchronous motors control the magnetic flux to decrease as the load decreases, so that the loss of the motor decreases, and the efficiency and power factor increase accordingly, but the ideas are different, and the performance is also different. long.

In the existing research literature on energy saving of asynchronous motors, the main methods can be divided into two categories: minimum loss model control and search control.

The minimum loss model control is based on the mathematical description. By establishing the loss model of the asynchronous motor, the minimum point of the total loss can be analytically obtained. During operation control, slip angle frequency adjustment control and power factor control can be adopted according to the optimal operating point with the minimum loss of the motor. and vector control etc.

In the existing slip angle frequency regulation control, the mathematical model of asynchronous motor based on steady state ignores the core loss of the motor. By analyzing the loss and efficiency of the asynchronous motor, the slip angle frequency at the optimum efficiency is deduced. While the core loss accounts for about 20%-40% of the total loss of the motor when the asynchronous motor is running, so the energy-saving control method that ignores the core loss will inevitably have a greatly reduced energy-saving effect.

Contents of the invention

The purpose of the present invention is to provide an energy-saving control method for asynchronous motors, determine the optimal slip angle frequency of the asynchronous motor according to the parameters such as the resistance and inductance of the motor, and control the optimal slip angle frequency of the motor to run, so as to achieve energy saving of the asynchronous motor run.

For achieving the above object, technical scheme of the present invention is:

The invention considers the actual situation of the motor, and proposes an energy-saving method for the asynchronous motor based on the optimal slip angle frequency according to the steady-state motor mathematical model considering the iron core loss.

Specifically, an energy-saving control method for an asynchronous motor. The asynchronous motor is powered by an inverter and controlled by a speed regulator, and the speed regulator is regulated and controlled. The inverter includes a power module and a digital signal processor DSP. Control module; send the difference between the given motor angular velocity ω ^* and the measured motor’s actual angular velocity ω to the speed regulator, and the output of the speed regulator is the given electromagnetic torque of the motor ω _s ^* is the optimal slip angular frequency of the asynchronous motor, that is, when the motor is running at this slip angular frequency, the motor has the highest operating efficiency after the motor runs to a steady state; the optimal slip angular frequency ω _s ^* is:

${{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span>\sqrt{\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; r</span>}}}}<span\; class="notranslate">\; ,</span>$

Among them, R _s is the resistance of each phase of the stator of the controlled asynchronous motor, R _r is the resistance of each phase of the rotor, R _fe is the resistance of each phase representing the core loss of the motor, L _lr is the leakage inductance of each phase of the rotor, and L _r is the converted positive The self-inductance of each phase of the rotor after the two phases are crossed, L _m is the mutual inductance between the coaxial stator and rotor windings;

given electromagnetic torque And the optimal slip angular frequency ω _s ^* is calculated to obtain the torque current component Isq of the motor in the two-phase rotating coordinate system: Where n _p is the number of pole pairs of the asynchronous motor;

The excitation current component Isd of the asynchronous motor in the two-phase rotating coordinate system is calculated from the torque current component Isq and the optimal slip angular frequency ω _s ^* :

According to the torque current component Isq and the excitation current component Isd of the stator current, the stator two-phase voltage Usd and Usq in the steady-state operation state are obtained respectively:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>\frac{{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; d</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; )</span>\end{array}\right.$

Among them, L _S is the self-inductance of each phase of the stator winding in the two-phase coordinate system, ω ₁ is the angular frequency of the power supply, which is equal to the sum of the optimal slip angular frequency ω _s ^* and the actual angular velocity ω of the motor; the angular frequency of the power supply is integrated Obtain the rotation angle θ of the rotor; the two-phase voltages Usd and Usq and the rotation angle θ are processed by reverse Parker operation ipark, that is, the two-phase voltage components Usα and Usβ of the asynchronous motor in the two-phase stationary coordinate system are obtained, and then through the space vector pulse width modulation SVPWM controls the inverter to realize the energy-saving control of the asynchronous motor.

Further, the actual angular velocity ω of the motor can be detected by the speed sensor, or the motor speed can be identified by detecting the motor current and voltage using the model reference adaptive method, the sliding film observer method, and the extended Kalman filter method.

In addition, the speed sensor includes a photoelectric encoder, a rotary transformer, or a tachogenerator.

The asynchronous motor is powered by an inverter, and the inverter INV. is powered by direct current.

In addition, the direct current can come from a lithium battery, a supercapacitor, or be rectified by an alternating current through a diode.

The power module of the inverter is an insulated gate bipolar transistor IGBT, or a metal-oxide semiconductor field effect transistor MOSFET.

In the "T" equivalent circuit diagram of the asynchronous motor in steady state operation, the resistance representing the core loss and the exciting inductance can be processed in parallel or in series. The present invention adopts the latter mode, that is, the iron core loss resistance is connected in series with the excitation inductance as shown in Fig. 1 .

Beneficial effects of the present invention:

The invention makes the asynchronous motor run at the highest efficiency by controlling the asynchronous motor to run at the optimum slip angle frequency. The application of the energy-saving control method of the present invention enables the asynchronous motor powered by the inverter to operate with the lowest loss regardless of the operating conditions, and is especially suitable for fan and water pump loads or low-speed and often light-loaded operating places. It is especially suitable for applications that are sensitive to the use time of a single charge, such as pure electric rotorcraft and electric vehicles.

The method of the present invention can be used in combination with search control. That is to implement search control in a small range near the optimal slip angle frequency to further improve the energy-saving control effect.

The method of the invention is not only suitable for asynchronous motor systems with speed sensors, but also suitable for asynchronous motor systems without speed sensors.

Description of drawings

Fig. 1 is the equivalent circuit diagram of the asynchronous motor of the present invention.

Fig. 2 is a schematic diagram of an embodiment of the present invention.

detailed description

Referring to Fig. 1, Fig. 2, a kind of energy-saving control method of asynchronous motor of the present invention, this asynchronous motor M is powered by inverter INV., and inverter INV. is powered by direct current U _dc ; , Inverter INV. Including a power module and a control module 1 containing a digital signal processor DSP; the difference between the given motor angular velocity ω ^* and the measured motor angular velocity ω is sent to the speed regulator PI, and the speed regulator PI output is the given electromagnetic torque of the motor ω _s ^* is the optimal slip angular frequency of the asynchronous motor, that is, when the motor is running at this slip angular frequency, the motor has the highest operating efficiency after the motor runs to a steady state; the optimal slip angular frequency ω _s ^* is:

${{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}^{<span\; class="notranslate">\; *</span>}<span\; class="notranslate">\; =</span>\sqrt{\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; r</span>}}}}<span\; class="notranslate">\; ,</span>$

Among them, R _s is the resistance of each phase of the stator of the controlled asynchronous motor, R _r is the resistance of each phase of the rotor, R _fe represents the resistance of each phase of the core loss of the motor, L _lr is the leakage inductance of each phase of the rotor, and L _r is transformed into two quadrature phases The self-inductance of each phase of the rotor, the mutual inductance between L _m coaxial stator and rotor windings;

given electromagnetic torque And the optimal slip angular frequency ω _s ^* is calculated to obtain the torque current component Isq of the motor in the two-phase rotating coordinate system: Where n _p is the number of pole pairs of the asynchronous motor;

The excitation current component Isd of the asynchronous motor in the two-phase rotating coordinate system is calculated from the torque current component Isq and the optimal slip angular frequency ω _s ^* :

According to the torque current component Isq and the excitation current component Isd of the stator current, the stator two-phase voltage Usd and Usq in the steady-state operation state are obtained respectively:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; -</span>\frac{{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; d</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; )</span>\end{array}\right.$

Among them, L _S is the self-inductance of each phase of the stator winding in the two-phase coordinate system, ω ₁ is the angular frequency of the power supply, which is equal to the sum of the optimal slip angular frequency ω _s ^* and the actual angular velocity ω of the motor; the angular frequency of the power supply is integrated The rotation angle θ of the rotor is obtained; the two-phase voltage Usd and Usq and the rotation angle θ are processed by the anti-pike operation ipark, that is, the two-phase voltage components Usα and Usβ of the asynchronous motor in the two-phase stationary coordinate system are obtained, and then through the space vector pulse width Modulate the SVPWM to control the inverter INV. to realize the energy-saving control of the asynchronous motor M.

Further, the actual angular velocity ω of the motor can be detected by the speed sensor, or the motor speed can be identified by detecting the motor current and voltage using the model reference adaptive method, the sliding film observer method, and the extended Kalman filter method.

The speed sensor includes a photoelectric encoder or a rotary transformer, a tachogenerator, and the like.

The direct current U _dc can come from a lithium battery, a supercapacitor, or be rectified by an alternating current through a diode.

The power module of the inverter INV. is an insulated gate bipolar transistor IGBT, or a metal-oxide semiconductor field effect transistor MOSFET.

To sum up, the present invention makes the asynchronous motor run at the highest efficiency by controlling the asynchronous motor to run at the optimal slip angle frequency.

Claims (6)

1. an energy-saving control method for asynchronous machine, this asynchronous machine by inverter power supply, and is regulated by speed regulator, controls, and inverter comprises power model and the control module containing digital signal processor DSP; By the difference of given motor angular velocity ω * with the angular velocity omega of the motor reality recorded, send into speed regulator, speed regulator output variable is the given electromagnetic torque T of motor _e*; ω _s* be the optimum slip angular frequency that asynchronous machine runs, when namely motor runs with this slip angular frequency, after motor moves to stable state, the operational efficiency of motor is the highest; Optimum slip angular frequency ω _s* be:

${{\mathrm{\&omega;}}_s}^{*}=\sqrt{\frac{R_r^2(R_s+R_{fe})}{R_s{L}_r^2+R_r{L}_m^2+R_{fe}{L}_r{L}_{1r}}},$

Wherein, R _sfor the every phase resistance of controlled asynchronous machine stator, R _rfor the every phase resistance of rotor, R _fefor characterizing every phase resistance, the L of electric machine iron core loss _lrfor the every phase leakage inductance of rotor, L _rfor converting the every phase self-induction of the rotor after orthogonal two-phase to, L _mfor the mutual inductance between coaxial stator and rotor winding;

By given electromagnetic torque T _e* with optimum slip angular frequency ω _s* through calculating the torque current component Isq of motor under two-phase rotating coordinate system: wherein n _pfor the number of pole-pairs of asynchronous motor;

By torque current component Isq and optimum slip angular frequency ω _s* calculate and ask for the excitation current component Isd of asynchronous machine under two-phase rotating coordinate system:

Stator two-phase voltage U sd and Usq under steady-state operating condition is obtained respectively according to the torque current component Isq of stator current and excitation current component Isd:

$\left\{\begin{array}{c}{u}_{sd}=R_s{i}_{sd}-{\mathrm{\&omega;}}_1(L_s-\frac{{L_m}^2}{L_r})i_{sq}+R_{fe}{i}_{sd}\\ u_{sq}=R_s{i}_{sq}+{\mathrm{\&omega;}}_1{L}_s{i}_{sd}+R_{fe}{i}_{sq}(1-\frac{L_m}{L_r})\end{array}\right.$

Wherein, L _sbe the every phase self-induction of stator winding under two phase coordinate systems, ω ₁for power supply angular frequency, it equals optimum slip angular frequency ω _s* with the angular velocity omega sum of motor reality; Power supply angular frequency obtains the rotation angle θ of rotor through integral operation; By two-phase voltage U sd and Usq and rotation angle θ through villain gram computing ipark, namely the two-phase component of voltage Us α of asynchronous machine under two-phase rest frame and Us β is obtained, and then through space vector pulse width modulation SVPWM control inverter, realize the Energy Saving Control of asynchronous machine.

2. the energy-saving control method of asynchronous machine as claimed in claim 1, it is characterized in that, the angular velocity omega Negotiation speed transducer of described asynchronous machine reality detects and obtains, or by the electric current of detection asynchronous machine, the angular velocity omega of voltage employing adaptive method, synovial membrane observer method or EKF method identification asynchronous machine.

3. the energy-saving control method of asynchronous machine as claimed in claim 2, it is characterized in that, described velocity transducer comprises photoelectric encoder or resolver, tachogenerator.

4. the energy-saving control method of asynchronous machine as claimed in claim 1, it is characterized in that, described asynchronous machine is by inverter power supply, and inverter is by direct current U _dcpower supply.

5. the energy-saving control method of asynchronous machine as claimed in claim 4, is characterized in that, direct current U _dcfrom lithium battery, super capacitor or obtained through over commutation by alternating current.

6. the energy-saving control method of asynchronous machine as claimed in claim 1, it is characterized in that, the power model of described inverter is insulated gate bipolar transistor IGBT or metal-oxide layer semiconductcor field effect transistor MOSFET.