Induction motor field-oriented deviation compensation control method based on voltage feedback

Abstract

The application relates to the technical field of induction motor magnetic field orientation deviation compensation, and discloses an induction motor magnetic field orientation deviation compensation control method based on voltage feedback, which comprises the following steps: S1, calculating a current vector angle and a voltage reference value; obtaining a voltage error according to the difference between the voltage reference value and a feedback voltage; S2, obtaining a magnetic field deflection angle according to the voltage error, and calculating a current angle tangent value after magnetic field orientation correction according to the magnetic field deflection angle; S3, calculating a real current angle tangent state Z1 and a slip disturbance state Z2 of the system, and constructing a state matrix; S4, calculating a slip compensation amount according to the state matrix, and calculating a slip angular velocity in real time; and S5, feeding back the slip angular velocity to the system, and compensating the magnetic field orientation deviation according to the real-time calculated slip instruction. The application solves the problem of orientation deviation caused by the time-varying of incremental inductance and rotor resistance, can correct the magnetic field orientation deviation in real time, reduces the deviation between the actual torque and the instruction, and improves the efficiency and stability of the electric drive system.

Description

Technical Field

[0001] This invention relates to the field of indirect rotor magnetic field orientation deviation compensation technology for induction motors, and specifically to a control method for magnetic field orientation deviation compensation of induction motors based on voltage feedback. Background Technology

[0002] In existing technologies, four methods are commonly used to control induction motors: variable frequency control, vector control, direct torque control, and predictive control. However, variable frequency control has a long response time and poor dynamic performance, direct torque control has torque fluctuation problems, and predictive control has problems with computational complexity and robustness. In order to achieve efficient, high-precision, and high dynamic response control of induction motors, vector control is often used in industry.

[0003] Vector control, also known as rotor field-oriented control, includes indirect rotor field-oriented control (IFOC) and direct rotor field-oriented control. Among them, indirect rotor field-oriented control is considered a practical control strategy due to its high reliability and is widely used in industrial fields.

[0004] The control performance of IFOC is greatly affected by the accuracy of field orientation. The key factors influencing field orientation accuracy are the incremental inductance and rotor resistance, which are in turn affected by the core saturation level and rotor temperature. However, core saturation and rotor temperature are immeasurable quantities. Current technology obtains the incremental inductance and rotor resistance under rated conditions through offline identification and measurement, and writes these values ​​into the motor control algorithm. During control, the pre-written values ​​are used. This results in these values ​​being fixed and cannot be corrected during actual control. Consequently, the preset incremental inductance and rotor resistance cannot be updated in real time with changes in motor conditions, leading to field orientation deviation and torque error. In applications requiring high control precision, this can easily cause serious control problems. Furthermore, field orientation deviation can reduce the efficiency of the electric drive system and may even lead to overcurrent problems at high speeds.

[0005] In summary, there is a need to provide a voltage feedback-based induction motor magnetic field orientation deviation compensation control method to improve control accuracy. Summary of the Invention

[0006] This invention aims to provide a voltage feedback-based induction motor field orientation deviation compensation control method. It fully utilizes measurable voltage error information to obtain the unmeasurable field deviation angle, solving the problem of unmeasurable core saturation and rotor temperature. After expanding system disturbances, it constructs an active disturbance rejection deviation compensation control structure, enabling the incremental inductance and rotor resistance to be updated in real time according to the changes in motor state during the control process. This reduces field orientation deviation and torque error, improves control accuracy and reliability, and enhances control efficiency.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a voltage feedback-based induction motor magnetic field orientation deviation compensation control method, comprising the following steps:

[0008] S1, calculate the tangent of the current vector angle tanθ based on the input excitation current reference value and torque current reference value. R ;

[0009] S2, obtain the feedforward reference voltage value and voltage temperature rise correction value The voltage reference value is calculated based on the feedforward reference voltage value and the voltage temperature rise correction value. According to voltage reference value Calculated voltage error in,

[0010]

[0011] In the formula, k r and k l These are the compensation coefficients for changes in resistance and inductance, respectively; ω s Select the angular velocity for the stator magnetic field; T s It is the stator temperature. It is a fixed room temperature;

[0012] S3, the magnetic field deflection angle is calculated based on the voltage error, and the tangent of the current angle tanθ after magnetic field orientation correction is calculated based on the magnetic field deflection angle; where...

[0013] Magnetic field deflection angle

[0014] In the formula, ω s To select the angular velocity for the stator magnetic field, L s For stator inductance, i T For real-time torque current, R s For stator resistance, i M This is the real-time excitation current;

[0015] S4. The actual current tangent state Z1 and slip disturbance state Z2 of the system are calculated using the linear extended state observer module, and the state matrix [Z1 Z2] to be observed is constructed. T ;

[0016] S5, based on the state matrix [Z1 Z2] T And the obtained current vector angle tangent tanθ R Calculate the slip compensation amount The slip angular velocity ω is calculated in real time based on the current tangent tanθ, the incremental inductance, and the rotor resistance. f ,

[0017]

[0018] In the formula, T r s is the rotor time constant; s is the Laplace operator;

[0019] S6 calculates the slip command based on the real-time calculated slip angular velocity to compensate for the magnetic field orientation deviation.

[0020] The principle and advantages of this scheme are:

[0021] Since the accuracy of magnetic field orientation has a significant impact on the control performance of IFOC, and the key issue with IFOC is that the incremental inductance and rotor resistance are affected by the core saturation level and rotor temperature, both of which are immeasurable, current technologies can only control based on rated values. This makes it easy for deviations to occur during control due to motor conditions, leading to control errors and serious control problems.

[0022] Because a deviation in magnetic field orientation will cause the actual voltage to deviate from the reference voltage, this scheme departs from the logic of obtaining the core saturation level and rotor temperature. Instead, it indirectly obtains the unmeasurable magnetic field deviation angle through measurable voltage error information. One key aspect of this scheme is establishing an accurate reference voltage model. Traditional indirect rotor magnetic field orientation control algorithms for induction motors lack a reference voltage model, thus failing to obtain voltage error information and not considering using a readily known voltage for measuring the magnetic field orientation deviation angle. However, after studying and analyzing a large amount of experimental data, this scheme found that the reference voltage is theoretically related to temperature, speed, and torque. Therefore, considering these three states, a high-precision voltage reference model was established. Another key aspect is the establishment of a high-performance magnetic field orientation deviation compensation controller based on the principle of active disturbance rejection (ADDR). Under the premise of expanding system disturbances, an ADDR magnetic field deviation compensation control structure is constructed, which corrects the magnetic field orientation deviation by compensating for the rated slip. This scheme can quickly and accurately correct the magnetic field orientation deviation without requiring accurate incremental inductance and rotor resistance, significantly reducing torque error and improving the efficiency of the electric drive system. Attached Figure Description

[0023] Figure 1 This is a block diagram of the control method according to an embodiment of the present invention;

[0024] Figure 2 This is an example diagram showing the calibration results of the feedforward reference voltage module according to an embodiment of the present invention;

[0025] Figure 3 This is a bottom-level block diagram of the linear extended state observer module according to an embodiment of the present invention;

[0026] Figure 4 This is a bottom-level block diagram of the linear state error feedback control module according to an embodiment of the present invention;

[0027] Figure 5 This is a comparison chart of the output torque error before and after applying the present invention to compensate for magnetic field deviation when the motor state changes during motor operation, as shown in this embodiment of the invention. Detailed Implementation

[0028] The following detailed description illustrates the specific implementation method:

[0029] Example

[0030] The voltage feedback-based induction motor field orientation deviation compensation control method in this embodiment establishes a mathematical model of the field deviation angle and voltage error. It realizes the observation of the unmeasurable field deviation angle based on the measurable voltage error. After expanding the system disturbance, it constructs an active disturbance rejection deviation compensation control structure to improve the reliability of the algorithm, enhance the control effect, and make the control response faster and without overshoot.

[0031] For details, see attached. Figure 1 As shown, the input to the control method is the excitation current reference value. Torque current reference value Voltage feedback value Voltage vector, stator temperature T s The output is the slip angular velocity (ω). f The magnetic field orientation deviation is corrected by compensating for the rated slip. The specific control method is as follows:

[0032] (1) Based on the calibrated excitation current reference value and torque current reference value The current vector angle in the rotating coordinate system is calculated in real time using the current angle calculation module, and the tangent value of the current angle reference value is used. express.

[0033] (2) The current voltage reference value is calculated in real time using the reference voltage module. In this embodiment, the reference voltage module includes a feedforward reference voltage module and a voltage temperature rise correction module. The feedforward reference voltage value is obtained through the feedforward reference voltage module. In this embodiment, the feedforward reference voltage model is obtained from a room temperature calibration experiment, denoted as . like Figure 2 As shown in the figure, the coordinates represent speed and torque, respectively. The real-time feedforward reference voltage can be obtained based on the real-time torque command and speed feedback. The motor temperature is measured by sensors. The real-time values ​​of torque current and excitation current are known quantities in the algorithm. The voltage temperature rise correction value is obtained using the voltage temperature rise correction module, and the voltage is calibrated. The voltage temperature rise correction value is... in

[0034]

[0035] In the formula, k r and k l These are the compensation coefficients for changes in resistance and inductance, respectively; ω s Select the angular velocity for the stator magnetic field; T s It is the stator temperature, obtained from a temperature sensor; It is a fixed room temperature.

[0036] The reference voltage module outputs a final voltage reference value after taking temperature changes into account, which is expressed as follows:

[0037] (3) Calculate the voltage error based on the obtained voltage reference value, expressed as:

[0038] In the formula, The voltage vector is the current input voltage feedback value.

[0039] (4) Based on the voltage error, stator magnetic field rotation angular velocity, excitation current, torque current, and stator resistance, the magnetic field deflection angle is calculated in real time using the magnetic field deviation angle module, and is expressed as follows:

[0040]

[0041] Simultaneously, based on the magnetic field deflection angle, the tangent of the current angle after magnetic field orientation correction is calculated, expressed as:

[0042] tan0=tan(0 R +e θ );

[0043] Where, ω s To select the angular velocity for the stator magnetic field, L s For stator inductance, i T For real-time torque current, R s For stator resistance, iM This is the real-time excitation current.

[0044] (5) After obtaining the current angle tangent, the slip disturbance and the true current angle tangent of the system are calculated using the Linear Extended State Observer (LESO) module. The true current angle tangent is the first state (Z1), and the slip disturbance of the system is the second state (Z2). In this embodiment, since the slip disturbance Z2 is not the true state, Z2 is a state constructed through extension. The Linear Extended State Observer (LESO) module calculates the system disturbance state (Z2) and current angle state (Z1) caused by parameter misalignment in real time based on the calculated slip angular velocity and the true current angle tangent tanθ.

[0045] The state matrix [Z1 Z2] to be observed is constructed by Z1 and Z2 together. T To form a mathematical model, combined with Figure 3 As shown, the state-space expression of its mathematical model is as follows:

[0046]

[0047] In the formula, β1 is the linear feedback correction coefficient of Z1, and β2 is the linear feedback correction coefficient of Z2.

[0048] (6) Based on the obtained Z1 and Z2, the linear state error feedback control module (LSEF) and the calculated current vector angle value tanθ are used to control the linear state error feedback module (LSEF). R Calculate the slip compensation amount Combination Figure 4 As shown, the expression is

[0049]

[0050] In the formula, k c This is the bandwidth parameter for linear state error feedback control, which directly affects the dynamic response performance of the controller.

[0051] (7) Based on the calculated current tangent tanθ, incremental inductance, and rotor resistance, the slip angular velocity is calculated in real time using the slip calculation module. The expression is as follows:

[0052]

[0053] Among them, T r =L r / R r T r L is the rotor time constant of the induction motor, which is an offline fixed value. r R is the rated value of the incremental inductance. ris the rated value of the rotor resistance; s is the Laplace operator. The slip command is calculated in real time based on the slip angular velocity. This slip command also includes the system disturbance (Z2). The magnetic field orientation deviation is compensated based on the slip command.

[0054] In this embodiment, the control method compensates for magnetic field orientation deviation during the control process without requiring precise knowledge of the incremental inductance and rotor resistance. A comparison of the control results before and after implementing this method is attached. Figure 5 As shown, attached Figure 5 In the diagram, the dashed line represents the output of the traditional IFOC control algorithm, and the solid line represents the output of the corrected control method. From... Figure 5 It is evident that, under the same conditions, this solution significantly reduces torque error, decreasing it by 3-5 Nm compared to the traditional IFOC control algorithm; it also effectively reduces motor operating temperature by 3-6 °C.

[0055] Since the accuracy of magnetic field orientation has a significant impact on the control performance of IFOC, and the key issue with IFOC is that the incremental inductance and rotor resistance are affected by the core saturation level and rotor temperature, both of which are unmeasurable, existing technologies can only control based on rated values. This makes it easy for deviations to occur during control due to motor conditions, leading to control errors and serious control problems. This solution overcomes the limitation of unmeasurable core saturation and rotor temperature by using the available excitation current reference value. and torque current reference value Considering parameters such as temperature, speed, and torque, the voltage error is obtained. Therefore, a mathematical model for high-precision magnetic field deflection angle and voltage error was established, and the unmeasurable magnetic field deflection angle e was realized based on the measurable voltage error. θ Based on observations, and after expanding the system disturbance (Z2), a self-disturbance-resistant magnetic field deviation compensation control structure is established to calculate the slip angular velocity ω in real time. f This allows for real-time calculation of slip commands, compensation for magnetic field orientation deviations, reduction of control errors, and improved response speed without overshoot. It effectively improves the efficiency of the electric drive system, avoids overcurrent problems at high speeds, and enhances the reliability of the control method.

[0056] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for compensating for field orientation deviation of an induction motor based on voltage feedback, characterized in that: Includes the following steps: S1, calculate the tangent of the current vector angle tanθ based on the input excitation current reference value and torque current reference value. R ; S2, obtain the feedforward reference voltage value and voltage temperature rise correction value The voltage reference value is calculated based on the feedforward reference voltage value and the voltage temperature rise correction value. According to voltage reference value Obtain voltage error in, In the formula, k r and k l These are the compensation coefficients for changes in resistance and inductance, respectively; ω s Select the angular velocity for the stator magnetic field; T s It is the stator temperature. It is a fixed room temperature; S3, the magnetic field deflection angle is calculated based on the voltage error, and the tangent of the current angle tanθ after magnetic field orientation correction is calculated based on the magnetic field deflection angle; where... Magnetic field deflection angle In the formula, ω s To select the angular velocity for the stator magnetic field, L s For stator inductance, i T For real-time torque current, R s For stator resistance, i M This is the real-time excitation current; S4. The actual current tangent state Z1 and slip disturbance state Z2 of the system are calculated using the linear extended state observer module, and the state matrix [Z1 Z2] to be observed is constructed. T ; S5, based on the state matrix [Z1 Z2] T And the obtained current vector angle tangent tanθ R Calculate the slip compensation amount The slip angular velocity ω is calculated in real time based on the current tangent tanθ, the incremental inductance, and the rotor resistance. f , In the formula, T r s is the rotor time constant; s is the Laplace operator; S6 calculates the slip command based on the real-time calculated slip angular velocity to compensate for the magnetic field orientation deviation.

2. The induction motor field orientation deviation compensation control method based on voltage feedback according to claim 1, characterized in that: In S1, the tangent of the current vector angle In the formula, This is the reference value for the input excitation current; This is the reference value for the input torque current.

3. The induction motor magnetic field orientation deviation compensation control method based on voltage feedback according to claim 1, characterized in that: In S2, voltage error In the formula, This is the current input voltage feedback value.

4. The induction motor field orientation deviation compensation control method based on voltage feedback according to claim 1, characterized in that: In S2, the feedforward reference voltage value Obtained from room temperature calibration experiments.

5. The induction motor magnetic field orientation deviation compensation control method based on voltage feedback according to claim 1, characterized in that: In S3, the tangent of the current angle is tanθ = tan(θ). R +e θ ).

6. The induction motor field orientation deviation compensation control method based on voltage feedback according to claim 1, characterized in that: In S4, the linear expansion state observer module calculates in real time the system disturbance state Z2 and the current tangent state Z1 caused by the misalignment of incremental inductance and rotor resistance parameters based on the feedback slip angular velocity and current tangent value.

7. The induction motor field orientation deviation compensation control method based on voltage feedback according to claim 6, characterized in that: The state-space expression of the state matrix [Z1 Z2]T is as follows: In the formula, β1 is the linear feedback correction coefficient of Z1, and β2 is the linear feedback correction coefficient of Z2.

8. The induction motor magnetic field orientation deviation compensation control method based on voltage feedback according to claim 1, characterized in that: In S5, the slip compensation amount is calculated through the linear state error feedback control module. In the formula, k c This is the bandwidth parameter for linear state error feedback control.

9. The induction motor magnetic field orientation deviation compensation control method based on voltage feedback according to claim 1, characterized in that: In S5, T r It is the rotor time constant of the induction motor, and T is defined. r =L r / R r L r R is the rated value of the rotor inductance. r This is the rated value of the rotor resistance.

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