阅读说明：本技术 一种异步电机运行效率优化方法及控制系统 (Asynchronous motor operation efficiency optimization method and control system ) 是由 李飞 姚欣 于 2019-08-19 设计创作，主要内容包括：本发明公开了一种异步电机运行效率优化方法及控制系统。该方法结合异步电机的闭环反馈控制技术,通过在现有的异步电机控制系统中的间接矢量控制过程中增设一个磁链优化环节,实现根据交轴控制电流I<Sub>q</Sub>的大小按照最佳比值λ来同步调整直轴控制电流I<Sub>d</Sub>的大小。所述最佳比值λ通过处理单元查询预设的交/直轴控制电流最佳比值表来获得。其中,所述交/直轴控制电流最佳比值表由现场工作人员记录的异步电机运行在任一转速ω且输入功率最低时,交轴控制电流I<Sub>q</Sub>和直轴控制电流I<Sub>d</Sub>的比值λ来构建。本发明通过一个实际测量的最佳比值λ来根据交轴控制电流I<Sub>q</Sub>设置直轴控制电流I<Sub>d</Sub>,兼顾了异步电机在轻负载时铁损不能忽略的情况,提高了到异步电机运行的效率。(The invention discloses an asynchronous motor operation efficiency optimization method and a control system. The method combines the closed loop feedback control technology of the asynchronous motor, and realizes the control of the current I according to the quadrature axis by adding a flux linkage optimization link in the indirect vector control process in the existing asynchronous motor control system q Synchronously adjusting the direct-axis control current I according to the optimal ratio lambda d The size of (2). The optimal ratio lambda is obtained by the processing unit inquiring a preset optimal ratio table of the alternating/direct axis control current. Wherein, when the asynchronous motor recorded by the site staff operates at any rotating speed omega and the input power is the lowest, the AC/DC shaft control current I of the optimal ratio table is controlled by the AC/DC shaft control current q And direct axis control current I d Is constructed by the ratio of. The invention controls the current I according to the quadrature axis by an optimum ratio lambda actually measured q Setting the direct-axis control current I d Give consideration to asynchronous electricityUnder the condition that the iron loss of the machine can not be ignored when the machine is under light load, the running efficiency of the asynchronous motor is improved.)

1. A method for optimizing the running efficiency of an asynchronous motor comprises the following steps: :

through observing and constructing the input power of the asynchronous motor, an optimal ratio table of alternating/direct axis control current, which records the optimal ratio lambda of alternating axis control current value, alternating axis control current and direct axis control current of the asynchronous motor when the asynchronous motor operates at any rotating speed omega in a group of different rotating speeds and the input power is the lowest, is stored;

quadrature axis control current I based on asynchronous motor operation_qInquiring the optimal ratio table of the alternating/direct axis control current to obtain the corresponding optimal ratio lambda_yControlling the current I according to the quadrature axis_qThe optimum ratio λ_yTo set the direct axis control current I of the asynchronous machine_d。

2. The method for optimizing the operating efficiency of an asynchronous machine according to claim 1, further comprising:

a rotating speed control outer ring is arranged in a control circuit of the asynchronous motor to realize automatic adjustment of the rotating speed of the asynchronous motor, and the rotating speed of the asynchronous motor is adjusted to a preset rotating speed value;

control of the asynchronous machineA current control inner ring is arranged in the control circuit to realize the quadrature axis control current I of the asynchronous motor_qDirect axis control current I_dAnd the sizes of the two are automatically adjusted to meet the optimal ratio of the optimal ratio table of the alternating/direct axis control current.

3. The method for optimizing the operating efficiency of the asynchronous motor according to claim 2, wherein the outer ring of the rotational speed control is specifically configured to: according to a preset rotation speed omega_ySubtracting the detected rotor angular frequency omega of the asynchronous machine_rObtaining corresponding difference value, and calculating corresponding quadrature axis feedback current I by a current calculation module according to the difference value_qsThe obtained quadrature axis feedback current I_qsGenerating quadrature axis control current I of asynchronous motor by integration through PI regulator_q(ii) a The current control inner ring is specifically set as follows: the direct axis control current I to be obtained by the method of claim 1_dFlux linkage current I with direct axis of asynchronous motor_dFPerforming difference making, and integrating the obtained difference value through a corresponding PI regulator to obtain a direct axis control voltage for controlling SVPWM to generate a three-phase driving voltage for controlling the inverter; the obtained cross-axis control current I_qFlux linkage current I intersecting with asynchronous motor_qFAnd (4) performing difference making, and integrating the obtained difference value through a corresponding PI regulator to obtain quadrature axis control voltage for controlling a space vector modulator (SVPWM) to generate three-phase driving voltage for controlling the inverter.

4. The asynchronous motor operation efficiency optimization method according to any one of claims 1 to 3, wherein the current I is controlled based on a quadrature axis during the operation of the asynchronous motor_qInquiring the optimal ratio table of the alternating/direct axis control current to obtain the corresponding optimal ratio lambda_y(ii) a The concrete implementation is as follows: if the optimal ratio table of the AC/DC axis control current is equal to the AC axis control current I_qThe quadrature axis control current value is directly obtained_qThe corresponding optimal ratio lambda is used as the ratio lambda under the preset rotating speed_y(ii) a If the optimal ratio of the AC/DC axis control current is not equal to the AC axis control current I_qThe quadrature axis control current value is greater than and closest to the quadrature axis control current value I_qQuadrature axis control current value I_aCorresponding lambda_aIs less than and closest to the quadrature axis control current value I_qI corresponding to the quadrature axis control current value_bThe quadrature axis control current value I is calculated according to the following formula_qCorresponding lambda_y：

5. The method for optimizing operating efficiency of an asynchronous motor according to claim 4, wherein the current I is controlled according to the quadrature axis_qThe optimum ratio λ_yTo set the direct axis control current I of the asynchronous machine_dSpecifically, I is obtained by the following formula_d：I_d＝I_q/λ_y。

6. An asynchronous machine operating efficiency optimizing control system is characterized in that: the flux linkage optimization module comprises a storage module and a processing unit, wherein the storage module is used for storing an optimal ratio table of alternating/direct axis control current;

the optimal ratio table of the alternating current/direct current is constructed by observing the input power of the asynchronous motor when the asynchronous motor operates at different rotating speeds, wherein the optimal ratio lambda of the alternating current value, the alternating current value and the direct current value of the asynchronous motor is recorded when the asynchronous motor operates at any rotating speed omega in a group of different rotating speeds and the input power is the lowest;

the processing unit is used for controlling the current I based on the quadrature axis of the asynchronous motor during operation_qInquiring the optimal ratio table of the alternating/direct axis control current to obtain the corresponding optimal ratio lambda_yControlling the current I according to the quadrature axis_qThe optimum ratio λ_yTo set the direct axis control current I of the asynchronous machine_d。

7. The system for optimizing the operating efficiency of an asynchronous motor according to claim 6, wherein the system combines a dual-control closed loop of a rotating speed control outer ring and a current control inner ring to realize the feedback regulation of the rotating speed and the control current of the asynchronous motor;

the rotating speed control outer ring is used for realizing automatic adjustment of the rotating speed of the asynchronous motor and adjusting the rotating speed of the asynchronous motor to a preset rotating speed value;

the current control inner ring is used for controlling the quadrature axis control current I of the asynchronous motor_qDirect axis control current I_dAnd the sizes of the two are automatically adjusted to meet the optimal ratio of the optimal ratio table of the alternating/direct axis control current.

8. The system for optimizing operating efficiency of an asynchronous motor according to claim 7, wherein said outer ring of speed control is implemented in detail as: according to a preset rotation speed omega_ySubtracting the detected rotor angular frequency omega of the asynchronous machine_rObtaining corresponding difference value, and calculating corresponding quadrature axis feedback current I by a current calculation module according to the difference value_qsThe obtained quadrature axis feedback current I_qsGenerating quadrature axis control current I of asynchronous motor by integration through PI regulator_q(ii) a The current control inner ring is specifically realized as follows: the direct axis control current I to be obtained by the method of claim 1_dFlux linkage current I with direct axis of asynchronous motor_dFPerforming difference making, and integrating the obtained difference value through a corresponding PI regulator to obtain a direct axis control voltage for controlling SVPWM to generate a three-phase driving voltage for controlling the inverter; the obtained cross-axis control current I_qFlux linkage current I intersecting with asynchronous motor_qFAnd (4) performing difference making, and integrating the obtained difference value through a corresponding PI regulator to obtain quadrature axis control voltage for controlling a space vector modulator (SVPWM) to generate three-phase driving voltage for controlling the inverter.

9. The system for optimally controlling the operating efficiency of the asynchronous motor according to any one of claims 6 to 8, wherein the processing unit controls the current I based on the quadrature axis when the asynchronous motor is operated_qInquiring the optimal ratio table of the alternating/direct axis control current to obtain the corresponding optimal ratio lambda_y(ii) a The specific process is as follows: inquiring whether the optimal ratio table of the alternating/direct axis control current is equal to the alternating axis control current I or not_qIf the quadrature axis control current value is existed, the quadrature axis control current value I is directly taken_qThe corresponding optimal ratio lambda is used as the ratio lambda under the preset rotating speed_y(ii) a Otherwise, respectively selecting the current values which are greater than and closest to the quadrature axis control current value I_qQuadrature axis control current value I_aCorresponding lambda_aIs less than and closest to the quadrature axis control current value I_qI corresponding to the quadrature axis control current value_bThe quadrature axis control current value I is calculated according to the following formula_qCorresponding lambda_y：

10. The system of claim 9 wherein the processing unit controls the current I according to the quadrature axis_qThe optimum ratio λ_yTo set the direct axis control current I of the asynchronous machine_dSpecifically, I is obtained by the following formula_d：I_d＝I_q/λ_y。

Technical Field

The invention provides a scheme for improving the running efficiency of an asynchronous motor, and relates to the field of power consumption control and energy conservation of the asynchronous motor. In particular to an optimization method and a control system for the running efficiency of an asynchronous motor.

Background

The asynchronous motor has higher operation efficiency under the rated load condition. However, when the motor is under light load, if the rated flux linkage is continuously maintained, the efficiency of the motor will be obviously reduced. Therefore, it is one of the focus of the engineers to research how to improve the operation efficiency of the motor.

The efficiency optimization of the existing asynchronous motor has the following two methods approximately;

based on an online search method: under the condition that the load torque is not changed, the rotor flux linkage is not adjusted, and the running efficiency of the asynchronous motor is improved by observing the voltage and the input current input by the system and reducing the iron loss and the copper loss of the motor. The method does not depend on motor model parameters, and has better applicability in the actual application process. However, in the method, a related sensor is required to be additionally arranged to detect the input voltage and the input current in the running process of the asynchronous motor, so that not only is the cost additionally increased, but also the input voltage and the input current of the asynchronous motor are required to be repeatedly observed and adjusted for multiple times to achieve the optimization of the running efficiency.

Optimizing the efficiency of the asynchronous motor based on the maximum torque current ratio: controlling the current I by making the direct axis with the stator current minimum as the control target under the condition that the asynchronous motor keeps a specific rotating speed_dAnd quadrature axis control current I_qWhen the input power of the motor is equal, the input power of the motor is theoretically minimum, and the purpose of optimizing efficiency is achieved. However, the method ignores the influence of the iron core loss along with the change of flux linkage and frequency, and the theory is different from the reality, so the method has certain limitation.

Disclosure of Invention

The optimization of the running efficiency of the asynchronous motor is quickly and accurately realized on the premise of repeatedly adjusting the input voltage and the input current without additionally arranging a sensor during the running of the asynchronous motor.

The invention provides an optimization method for the running efficiency of an asynchronous motor, which comprises the following steps: through observing and constructing the input power of the asynchronous motor, an optimal ratio table of alternating/direct axis control current, which records the optimal ratio lambda of alternating axis control current value, alternating axis control current and direct axis control current of the asynchronous motor when the asynchronous motor operates at any rotating speed omega in a group of different rotating speeds and the input power is the lowest, is stored; based on differencesQuadrature axis control current I when step motor operates_qInquiring the optimal ratio table of the alternating/direct axis control current to obtain the corresponding optimal ratio lambda_yControlling the current I according to the quadrature axis_qThe optimum ratio λ_yTo set the direct axis control current I of the asynchronous machine_d。

Further, quadrature axis control current I based on asynchronous motor operation_qInquiring the optimal ratio table of the alternating/direct axis control current to obtain the corresponding optimal ratio lambda_y(ii) a The concrete implementation is as follows: if the optimal ratio table of the AC/DC axis control current is equal to the AC axis control current I_qThe quadrature axis control current value is directly obtained_qThe corresponding optimal ratio lambda is used as the ratio lambda under the preset rotating speed_y(ii) a If the optimal ratio of the AC/DC axis control current is not equal to the AC axis control current I_qThe quadrature axis control current value is greater than and closest to the quadrature axis control current value I_qQuadrature axis control current value I_aCorresponding lambda_aIs less than and closest to the quadrature axis control current value I_qI corresponding to the quadrature axis control current value_bThe quadrature axis control current value I is calculated according to the following formula_qCorresponding lambda_y：

When no specific quadrature axis control current value exists in the constructed quadrature axis/direct axis control current optimal ratio table, the quadrature axis control current I corresponding to the specific quadrature axis control current value is calculated in a straight line fitting mode_qAnd direct axis control current I_dIs taken as the corresponding lambda_yAnd further better optimization of the operation efficiency is realized.

Correspondingly, the invention also provides an asynchronous motor operation efficiency optimization control system, which is characterized in that: the flux linkage optimization module comprises a storage module and a processing unit, wherein the storage module is used for storing an optimal ratio table of alternating/direct axis control current; the optimal ratio table of the alternating/direct axis control current is constructed by observing the input power when the asynchronous motor operates at different rotating speeds, whereinRecording the optimal ratio lambda of the quadrature axis control current value, the quadrature axis control current and the direct axis control current of the asynchronous motor when the asynchronous motor operates at any rotating speed omega in a group of different rotating speeds and the input power is the lowest; the processing unit is used for controlling the current I based on the quadrature axis of the asynchronous motor during operation_qInquiring the optimal ratio table of the alternating/direct axis control current to obtain the corresponding optimal ratio lambda_yControlling the current I according to the quadrature axis_qThe optimum ratio λ_yTo set the direct axis control current I of the asynchronous machine_d. The processing unit controls the current I according to the quadrature axis_qThe optimum ratio λ_yTo set the direct axis control current I of the asynchronous machine_dSpecifically, I is obtained by the following formula_d：I_d＝I_q/λ_y。

Further, the processing unit controls the current I based on the quadrature axis when the asynchronous motor runs_qInquiring the optimal ratio table of the alternating/direct axis control current to obtain the corresponding optimal ratio lambda_y(ii) a The specific process is as follows: inquiring whether the optimal ratio table of the alternating/direct axis control current is equal to the alternating axis control current I or not_qIf the quadrature axis control current value is existed, the quadrature axis control current value I is directly taken_qThe corresponding optimal ratio lambda is used as the ratio lambda under the preset rotating speed_y(ii) a Otherwise, respectively selecting the current values which are greater than and closest to the quadrature axis control current value I_qQuadrature axis control current value I_aCorresponding lambda_aIs less than and closest to the quadrature axis control current value I_qI corresponding to the quadrature axis control current value_bThe quadrature axis control current value I is calculated according to the following formula_qCorresponding lambda_y：

Drawings

Fig. 1a and 1b are respectively an equivalent circuit diagram and a simplified circuit diagram of an asynchronous motor considering iron loss;

fig. 2 is a system block diagram of an asynchronous motor operation efficiency optimization control system provided by the invention.

Detailed Description

In order to make the technical problems, technical solutions and advantages solved by the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The equivalent circuit of the asynchronous machine, as shown in fig. 1a, taking into account the iron losses, comprises the resistance Rs of the stator, the stator inductance LIs, the rotor inductance LIr, the mutual inductance Lm, the equivalent resistance Rfe due to the iron losses and the dynamic resistance Rr/s of the rotor. Since the pure inductor itself does not consume energy, the equivalent circuit diagram shown in fig. 1a can be simplified to obtain a simplified circuit diagram shown in fig. 1b in order to analyze the loss.

Mainly considering hysteresis loss in the core, i.e. loss P of the core_feThe model is as follows:

P_fe＝k₂*f^a*B²V (1)

wherein k is₂The magnetic induction motor is characterized by comprising a core, a magnetic induction coil, a magnetic. Then:

in the formula k₁The winding coefficient, N, the number of turns of the coil, U, the voltage at two ends of the iron core, the single-turn magnetic flux phi and the magnetic field intensity B are in a proportional relation. From the above equation 2, it can be seen that the equivalent resistance Rfe due to the iron loss is proportional to f^2-aIts magnitude is independent of the magnitude of the magnetic flux, and has a certain relation with the frequency. Under the condition that iron loss cannot be ignored, the direct axis control current I in the system_dSome of the quantities reflect the magnitude of the current through Rfe, so that an adjustment must be made to ids — iqs. We assume λ ═ iqs/ids; by adjusting λ, the effect of iron loss is also taken into account in the system. And finding a proper lambda by a calibration method on site. Further optimization of the efficiency of the asynchronous motor is achieved.

Based on the above analysisThe invention provides an asynchronous motor operation efficiency optimization method, which comprises the following steps: through observing and constructing the input power of the asynchronous motor, an optimal ratio table of alternating/direct axis control current, which records the optimal ratio lambda of alternating axis control current value, alternating axis control current and direct axis control current of the asynchronous motor when the asynchronous motor operates at any rotating speed omega in a group of different rotating speeds and the input power is the lowest, is stored; quadrature axis control current I based on asynchronous motor operation_qInquiring the optimal ratio table of the alternating/direct axis control current to obtain the corresponding optimal ratio lambda_yControlling the current I according to the quadrature axis_qThe optimum ratio λ_yTo set the direct axis control current I of the asynchronous machine_d. Controlling the current I according to the quadrature axis_qThe optimum ratio λ_yTo set the direct axis control current I of the asynchronous machine_dSpecifically, I is obtained by the following formula_d：I_d＝I_q/λ_y。

Quadrature axis control current I when asynchronous motor runs at any rotating speed omega and input power is lowest_qAnd direct axis control current I_dThe ratio λ of (d) can be obtained by the field worker by actually observing the input power of the motor in the manner described below. For a specific rotating speed omega 0, a field worker can set the asynchronous motor to operate at the specific rotating speed omega 0, and the direct-axis control current I when the rotating speed omega 0 input power is the lowest is obtained by observing the input power of the motor_dω0And quadrature axis control current I_qω0Ratio λ of_ω0。

Quadrature axis control current I based on asynchronous motor operation_qInquiring the optimal ratio table of the alternating/direct axis control current to obtain the corresponding optimal ratio lambda_y(ii) a The concrete implementation is as follows: if the optimal ratio table of the AC/DC axis control current is equal to the AC axis control current I_qThe quadrature axis control current value is directly obtained_qThe corresponding optimal ratio lambda is used as the ratio lambda under the preset rotating speed_y(ii) a If the optimal ratio of the AC/DC axis control current is not equal to the AC axis control current I_qThe cross axis control current value is greater than and closest to the cross axisControlling the current value I_qQuadrature axis control current value I_aCorresponding lambda_aIs less than and closest to the quadrature axis control current value I_qI corresponding to the quadrature axis control current value_bThe quadrature axis control current value I is calculated according to the following formula_qCorresponding lambda_y：

When no specific quadrature axis control current value exists in the constructed quadrature axis/direct axis control current optimal ratio table, the quadrature axis control current I corresponding to the specific quadrature axis control current value is calculated in a straight line fitting mode_qAnd direct axis control current I_dIs taken as the corresponding lambda_yAnd further better optimization of the operation efficiency is realized.

Furthermore, in order to realize the automatic feedback regulation of the rotating speed and the control current of the asynchronous motor, the feedback regulation of the rotating speed and the control current of the asynchronous motor can be realized by combining a double-control closed loop of a rotating speed control outer ring and a current control inner ring. Wherein, the outer ring of the rotational speed control can be realized as follows: according to a preset rotation speed omega_yRotor angular frequency omega of asynchronous motor obtained by subtracting sensor_rObtaining corresponding difference value, and inquiring corresponding quadrature axis feedback current I through a current calculation module according to the difference value_qs. The obtained quadrature axis feedback current I_qsGenerating quadrature axis control current I of asynchronous motor by integration through PI regulator_q. The rotating speed of the asynchronous motor can be finally stabilized at the preset rotating speed omega through the rotating speed control_y. The current control inner ring realizes the obtained cross-axis control current I_qFlux linkage current I intersecting with asynchronous motor_qFAnd (4) performing difference making, and integrating the obtained difference value through a corresponding PI regulator to obtain quadrature axis control voltage for controlling a space vector modulator (SVPWM) to generate three-phase driving voltage for controlling the inverter. The direct axis control current I obtained by the method_dFlux linkage current I with direct axis of asynchronous motor_dFAnd performing difference making, and integrating the obtained difference value through a corresponding PI regulator to obtain a direct-axis control voltage for controlling SVPWM to generate and control the three-phase driving voltage of the inverter.

The invention also provides an optimization control system for the running efficiency of the asynchronous motor. The system features as shown in fig. 2: comprising a control of the current I according to the quadrature axis of the asynchronous machine_qProportional setting of asynchronous motor direct axis control current I_dThe flux linkage optimization module. The flux linkage optimization module comprises a storage module and a processing unit, wherein the storage module stores an optimal ratio table of alternating/direct axis control current. The optimal ratio table of the alternating current/direct current control current records the optimal ratio lambda of the alternating current value, the alternating current value and the direct current value of the asynchronous motor when the asynchronous motor operates at any rotating speed omega in a group of different rotating speeds and the input power is the lowest; the data required by the AC/DC shaft control current optimal ratio table can be obtained by observing the input power of the asynchronous motor when the asynchronous motor operates at different rotating speeds by field workers. The processing unit is used for controlling the current I based on the quadrature axis of the asynchronous motor during operation_qInquiring the optimal ratio table of the alternating/direct axis control current to obtain the corresponding optimal ratio lambda_yControlling the current I according to the quadrature axis_qThe optimum ratio λ_yTo set the direct axis control current I of the asynchronous machine_d. The processing unit controls the current I according to the quadrature axis_qThe optimum ratio λ_yTo set the direct axis control current I of the asynchronous machine_dSpecifically, I is obtained by the following formula_d：I_d＝I_q/λ_y。

The system for controlling the running efficiency of the asynchronous motor optimally as shown in fig. 2 combines a rotating speed control outer loop and a current control inner loop double-control closed loop to realize the feedback regulation of the rotating speed of the asynchronous motor and the control current of the asynchronous motor.

Wherein, the outer ring of the rotation speed control is realized according to the preset rotation speed omega_yRotor angular frequency omega of asynchronous motor obtained by subtracting sensor_rObtaining corresponding difference value, and inquiring corresponding quadrature axis feedback current I through a current calculation module according to the difference value_qs. The obtained quadrature axis feedback current I_qsAfter being input into a first PI regulator 1PI for integration, the quadrature axis control current I is obtained through an amplitude limiter_q。

The current control inner ring is specifically realized as follows: the obtained cross-axis control current I_qFlux linkage current I intersecting with asynchronous motor_qFAnd performing PI integration on the obtained difference value by a second PI regulator 2 to obtain a quadrature axis control current for controlling a space vector modulator (SVPWM) to generate and control three-phase driving voltage of the inverter. Obtaining a direct axis control current I through the flux linkage optimization module_dFlux linkage current I with direct axis of asynchronous motor_dFAnd performing difference making, and integrating the obtained difference value through a third PI regulator to obtain a direct-axis control current for controlling SVPWM to generate the three-phase driving voltage for controlling the inverter. The direct axis flux linkage current I_dFAnd quadrature axis flux linkage current I_qFThe method comprises the steps that three-phase current of the asynchronous motor is collected through a sensor, two paths of current are obtained through an 3/2 converter, and stator electrical angle information is obtained through calculation through an Alpha/Beta conversion module.

The stator electrical angle information is obtained through the following steps: controlling the current I according to the quadrature axis_qThe result calculated by the slip gain module and the direct axis control current I_dAnd calculating to obtain the slip angular frequency. Rotor angular frequency omega obtained by sensor_rAdding the angular frequency of the slip to obtain the angular frequency omega of the stator_s. Using integrators for the resulting stator angular frequency omega_sIntegral is carried out to obtain stator electrical angle information phi required by the Alpha/Beta conversion module and the rotation conversion module_S。

Further, the processing unit controls the current I based on the quadrature axis when the asynchronous motor runs_qInquiring the optimal ratio table of the alternating/direct axis control current to obtain the corresponding optimal ratio lambda_y(ii) a The specific process is as follows: inquiring whether the optimal ratio table of the alternating/direct axis control current is equal to the alternating axis control current I or not_qIf the quadrature axis control current value is existed, the quadrature axis control current value I is directly taken_qThe corresponding optimal ratio lambda is used as the ratio lambda under the preset rotating speed_y(ii) a Otherwise, respectively selecting the current values which are greater than and closest to the quadrature axis control current value I_qQuadrature axis control current value I_aCorresponding lambda_aIs less than and closest to the quadrature axis control current value I_qOf (2)I corresponding to shaft control current value_bThe quadrature axis control current value I is calculated according to the following formula_qCorresponding lambda_y：

The technical scheme provided by the invention combines a closed-loop feedback control technology, and realizes the control of the current I through the quadrature axis by adding a flux linkage optimization link in the indirect vector control process in the existing asynchronous motor control system_qSynchronously adjusting the direct-axis control current I according to the optimal ratio lambda_dThe size of (2). Under the premise of considering the influence of iron loss, the optimization of the running efficiency of the asynchronous motor is quickly and accurately realized on the premise of observing the input voltage and the input current without additionally arranging a sensor when the asynchronous motor runs.