Deadbeat Predictive Current Control Method Based on Extended Notch State Observer

Abstract

The present invention discloses a deadbeat predictive current control method based on an extended notch state observer, which relates to the field of permanent magnet synchronous motor current control and includes: designing a cascaded extended state observer combined with a notch filter; designing a deadbeat predictive current control method for a permanent magnet synchronous motor based on the cascaded extended state observer combined with the notch filter to complete the deadbeat predictive current control based on the extended notch state observer. The present invention solves the problems of periodic disturbance amplification near the resonant frequency and complex stability judgment existing in the prior art.

Description

Technical Field

[0001] The present invention relates to the field of permanent magnet synchronous motor current control, and particularly to a deadbeat predictive current control method based on an extended notch state observer. Background Art

[0002] The deadbeat predictive current control of permanent magnet synchronous motors has been widely studied and applied in the field of permanent magnet synchronous motor control due to its strong dynamic performance. However, the deadbeat predictive current control is a typical model-based control method, and its prediction accuracy depends on the accuracy of the motor model. The inaccuracy of the motor model will affect the current prediction accuracy, thereby affecting the dynamic performance and steady-state performance of the system. In the actual application of the motor, factors such as temperature change and magnetic flux saturation will affect the electrical parameters of the motor, and the non-linearity of the inverter and current sampling error introduce complex disturbances to the motor model. How to handle the prediction error caused by the inaccurate motor model has become a current research hotspot.

[0003] The method based on disturbance observer compensation is based on the idea of disturbance estimation-compensation, observes the unknown disturbance in the motor model and compensates it into the prediction model to reduce the influence of the disturbance on the system control performance. The prior art proposes an adaptive integral type extended state observer to compensate for the disturbance caused by parameter mismatch and unmodeled terms, and establishes a bandwidth adaptive law to dynamically adjust the bandwidth of the observer. When the observation error is large, the fast convergence of the observer is realized. When the observer error is small, the small bandwidth of the observer avoids the high-frequency noise amplification caused by too high observer bandwidth. However, at steady state, affected by the small bandwidth, the ability of the observer to suppress periodic disturbances is still limited. The prior art also proposes to strengthen the ability of the system to suppress low-frequency disturbances by cascading extended state observers, but the ability to suppress periodic disturbances is still limited. The prior art also proposes to embed a resonant controller into the design of the extended state observer to achieve accurate estimation of periodic disturbances at specific frequencies. However, the periodic disturbances near the resonant frequency will be amplified, which deteriorates the control performance of the system to a certain extent. And when suppressing multiple periodic disturbances with different frequencies, the stability judgment of this method is complex.

[0004] However, the prior art has common problems such as amplification of periodic disturbances near the resonant frequency and complex stability judgment when combining the extended state observer with different controllers. This deteriorates the control performance of the system to a certain extent. Especially when the frequency of the periodic disturbance to be suppressed is high, the existing solutions inevitably amplify the high-frequency noise of the system, which instead deteriorates the control performance of the system. Summary of the Invention

[0005] Aiming at the above deficiencies in the prior art, the deadbeat predictive current control method based on an extended notch state observer provided by the present invention solves the problems of amplified periodic disturbances near the resonance frequency and complex stability judgment existing in the prior art.

[0006] In order to achieve the above invention purpose, the technical solution adopted by the present invention is: a deadbeat predictive current control method based on an extended notch state observer, including the following steps:

[0007] S1: Design a cascaded extended state observer combined with a notch filter;

[0008] S2: Based on the cascaded extended state observer combined with a notch filter, design a deadbeat predictive current control method for a permanent magnet synchronous motor to complete the deadbeat predictive current control based on an extended notch state observer.

[0009] Further, the cascaded extended state observer combined with a notch filter in S1 includes q d-axis DC disturbance extended state observer, q q-axis harmonic extended state observer, d d-axis DC disturbance extended state observer and d q-axis harmonic extended state observer.

[0010] Further, the q d-axis DC disturbance extended state observer is:

[0011]

[0012] Wherein, is the estimation error of the q d-axis DC disturbance extended state observer, is the q d-axis current of the permanent magnet synchronous motor, is the observed value of is q the d-axis DC disturbance observed value, is the reciprocal of the inductance of the permanent magnet synchronous motor, is the q d-axis voltage of the permanent magnet synchronous motor, is q the known quantity of the and are the gains of the DC disturbance extended state observer, and the superscript represents the first derivative.

[0013] Further, the q q-axis harmonic extended state observer is:

[0014]

[0015] Among them, is q the observation error of the n th harmonic expansion state observer of the axis, is the observed value of is q the th ( ) harmonic disturbance observed value of the th harmonic expansion state observer of the q axis. When = 0, is q the DC disturbance observed value of the DC disturbance observer of the axis, is the number of harmonic expansion state observers, is the gain of the harmonic expansion state observer, q is the harmonic disturbance observed on the axis with a frequency of , and are auxiliary variables,

[0016] Among them, is the notch bandwidth of the notch filter,

[0017] is the notch depth of the notch filter.

[0018] d

[0019]

[0020] Among them, is d the estimation error of the DC disturbance expansion state observer of the axis of the permanent magnet synchronous motor, d is the observed value of is the DC disturbance observed value of the d axis of the permanent magnet synchronous motor, is d the axis voltage of the permanent magnet synchronous motor, d

[0021] d Among them,

[0022]

[0023] Among them, is d the observation error of the n -th harmonic expansion state observer of the axis, is the observed value of is d the ( )-th harmonic disturbance observed value of the harmonic expansion state observer of the axis. When = 0, is d the DC disturbance observed value of the DC disturbance observer of the axis, is the number of harmonic expansion state observers, is d the harmonic disturbance with frequency observed on the axis, and are auxiliary variables, and are auxiliary variables, and are auxiliary variables;

[0024] .

[0025] Furthermore, in S2, a deadbeat predictive current control method for a permanent magnet synchronous motor is designed, and the formula is:

[0026]

[0027] Among them, is the current, is the current control moment, is the next control moment, is the state matrix, is the input parameter, is the additional input quantity, is the input voltage, is the disturbance estimated value;

[0028]

[0029]

[0030]

[0031]

[0032]

[0033] Among them, is the control period, is an inductor, and are respectively the permanent magnet synchronous motor d and q shaft current, and are respectively the permanent magnet synchronous motor d and q shaft voltage, and are respectively d and q shaft disturbance estimation values, is a resistance, is the electrical angular velocity, is the magnetic flux, and the superscript is the matrix transpose;

[0034] It is considered that , and the reference voltage is calculated as:

[0035]

[0036]

[0037]

[0038] wherein, is the reference input voltage, is the reference current, and are respectively d and q the q-axis reference input voltage, and are respectively d and q the d-axis reference input current;

[0039] According to the said reference voltage, the predicted current is made equal to the reference input value to achieve predictive current control.

[0040] The beneficial effects of the present invention are:

[0041] (1) The present invention embeds a notch filter into the extended state observer to achieve accurate estimation of specific frequencies and DC disturbances.

[0042] (2) The cascade design of the present invention separates the design of the DC disturbance extended state observer and the harmonic extended state observer, realizes the decoupling of the estimation of DC disturbances and periodic disturbances, and has a simple structure.

[0043] (3) The present invention solves the problem of amplified interference near the resonance frequency in the traditional method, prevents the influence of interference at other frequencies on the control performance, especially high-frequency noise. At the same time, the present invention has the advantages of simple stability analysis and parameter adjustment. Description of the Drawings

[0044] Figure 1 It is a flowchart of the deadbeat predictive current control method based on the extended notch state observer of the present invention.

[0045] Figure 2 It is an overall control block diagram of the deadbeat predictive current control method based on the extended notch state observer of the present invention.

[0046] Figure 3 is the transfer function at different Bode plots.

[0047] Figure 4 is the transfer function at different Bode plots.

[0048] Figure 5 is the transfer function at different Bode plots. Specific Embodiments

[0049] The present invention will be further described below in conjunction with the drawings and specific embodiments.

[0050] As Figure 1 shown, a deadbeat predictive current control method based on an extended notch state observer includes the following steps:

[0051] S1: Design a cascaded extended state observer combined with a notch filter;

[0052] S2: Based on the cascaded extended state observer combined with a notch filter, design a deadbeat predictive current control method for a permanent magnet synchronous motor to complete the deadbeat predictive current control based on the extended notch state observer.

[0053] In an embodiment of the present invention, considering the permanent magnet synchronous motor with unknown disturbances dq the d-axis current equation is:

[0054]

[0055] where, , are respectively dq the d-axis and q-axis lumped disturbances;

[0056] For simplicity, the above equation is rewritten as:

[0057]

[0058]

[0059] The cascaded extended state observer combined with a notch filter proposed by the present invention can be designed in two steps. The first step is: the design of a DC disturbance extended state observer, and the second step is: the design of a harmonic extended state observer.

[0060] The cascaded extended state observer combined with a notch filter in S1 includes q the d-axis DC disturbance extended state observer, q the q-axis harmonic extended state observer, d the D-axis DC disturbance extended state observer, and d the Q-axis harmonic extended state observer.

[0061] The q d-axis DC disturbance extended state observer is:

[0062]

[0063] Wherein, is q the estimation error of the d-axis DC disturbance extended state observer, is the q d-axis current of the permanent magnet synchronous motor, is the observed value of is q the observed value of the d-axis DC disturbance, is the reciprocal of the inductance of the permanent magnet synchronous motor, is the q d-axis voltage of the permanent magnet synchronous motor, is q the known quantity of the d-axis, and are the gains of the DC disturbance extended state observer, and the superscript represents the first derivative.

[0064] The q q-axis harmonic extended state observer is:

[0065]

[0066] Wherein, is q the observation error of the q-axis n nth harmonic extended state observer, is the observed value of is q the q-axis nth The harmonic disturbance observation value of the () harmonic expansion state observer. When = 0, is q the DC disturbance observation value of the DC disturbance observer on the axis. is the number of harmonic expansion state observers. is q the harmonic disturbance observed on the axis with a frequency of and are auxiliary variables. and are auxiliary variables. and are auxiliary variables;

[0067] The entire observer is composed of 1 DC disturbance observer and multiple harmonic disturbance observers, numbered from 0 to n. = 0 refers to the observation value of this DC disturbance observer. Starting from = 1, it is the observation value of the

[0068]

[0069] th harmonic disturbance observer; is the notch bandwidth of the notch filter. is the notch depth of the notch filter.

[0070] The d axis DC disturbance expansion state observer is:

[0071]

[0072] Among them, is d the estimated error of the axis DC disturbance expansion state observer. is the d axis current of the permanent magnet synchronous motor. is the observation value of is d the axis DC disturbance observation value. is the d axis voltage of the permanent magnet synchronous motor. is d the known quantity on the

[0073] The d axis harmonic expansion state observer is:

[0074]

[0075] ​Among them, is d the observation error of the n -th harmonic expansion state observer of the axis, is the observed value of is d the ( )-th harmonic disturbance observed value of the harmonic expansion state observer of the axis. When = 0, is d the DC disturbance observed value of the DC disturbance observer of the axis, is the number of harmonic expansion state observers, is d the harmonic disturbance with frequency observed on the axis, and are auxiliary variables, and are auxiliary variables, and are auxiliary variables;

[0076] .

[0077] Use the forward Euler formula for one-step prediction to compensate for the one-step delay caused by the microprocessor.

[0078] The deadbeat predictive current control method for the permanent magnet synchronous motor designed in S2 is as follows:

[0079]

[0080] Among them, is the current, is the current control moment, is the next control moment, is the state matrix, is the input parameter, is the additional input quantity, is the input voltage, is the disturbance estimated value;

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088] Among them, is the control period, is the inductor, and are the permanent magnet synchronous motor d and q shaft currents, and are the permanent magnet synchronous motor d and q shaft voltages, and are respectively d and q shaft disturbance estimation values, is the resistance, is the electrical angular velocity, is the magnetic flux, and the superscript is the matrix transpose;

[0089] It is considered that , and the reference voltage is calculated as:

[0090]

[0091]

[0092]

[0093] Among them, is the reference input voltage, is the reference current, and are respectively d and q axis reference input voltages, and are respectively d and q axis reference input currents;

[0094] According to the reference voltage, the predicted current is made equal to the reference input value to achieve predictive current control.

[0095] The control block diagram of the permanent magnet synchronous motor of the present invention is as shown in Figure 2 shown. For dqFor the unknown disturbances existing in the shaft, the present invention provides a cascaded extended state observer combined with a notch filter to observe the DC, low-frequency disturbance components and harmonic components in the unknown disturbances. The cascaded ESO combined with the notch filter includes a DC disturbance ESO and a harmonic ESO, and the two form a total observer in a cascaded form. Among them, the DC disturbance ESO is used to observe the DC and low-frequency disturbance components in the disturbance, and the harmonic ESO is used to observe the specific sub-harmonic components in the disturbance. The total disturbance observed by the observer is compensated into the deadbeat predictive current control (DPCC) algorithm to realize the correction of the output voltage.

[0096] In an embodiment of the present invention, taking q shaft as an example, when it is necessary to observe the DC disturbance and the harmonic with a frequency of , the disturbance observation error and the actual q shaft disturbance The transfer function between them is:

[0097]

[0098] Among them, is a complex variable.

[0099] Plot the Bode diagram of the above formula for different , and , as shown in Figures 3 - 5 , it can be found that the method proposed by the present invention has no amplification effect on the disturbances near the notch frequency, solves the problem of amplification of disturbances near the resonance frequency by the traditional method, and can freely adjust the notch bandwidth and notch depth through and , can observe harmonic disturbances more accurately, and the setting of a large bandwidth makes the harmonic extraction less sensitive to the harmonic frequency.

[0100] When there are multiple harmonics to be observed, the disturbance observation error transfer function becomes:

[0101]

[0102] It can be seen that the transfer function is realized by multiplication, the form is simple, and the bandwidth method can be used to tune and , that is, , , is the observer bandwidth. From the form of the transfer function, as long as , and are ensured, the system stability can be ensured.

[0103] The present invention provides an improved deadbeat current predictive control technology based on a cascaded extended state observer combined with a notch filter, which can achieve precise suppression of DC disturbances and harmonic disturbances at multiple specific frequencies. Through the cascaded structure, the estimation of DC disturbances and harmonic disturbances is decoupled, avoiding the amplification of disturbances near the notch frequency. Moreover, the method proposed by the present invention simplifies the transfer function of the system, reduces the complexity of system stability analysis, and greatly simplifies parameter tuning.

[0104] Those of ordinary skill in the art will realize that the embodiments described herein are for helping the reader understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific deformations and combinations that do not depart from the essence of the present invention based on the technical revelations disclosed in the present invention, and these deformations and combinations are still within the protection scope of the invention.

Claims

1. A deadbeat predictive current control method based on an extended notch state observer, characterized in that Including the following steps: S1: Design a cascaded extended state observer combined with a notch filter; S2: Based on the cascaded extended state observer combined with a notch filter, design a deadbeat predictive current control method for a permanent magnet synchronous motor to complete deadbeat predictive current control based on the extended notch state observer; The S1 cascade extended state observer includes q the d-axis DC disturbance extended state observer, q the q-axis harmonic extended state observer, d the d-axis DC disturbance extended state observer, and d the q-axis harmonic extended state observer; The said q axial DC disturbance extended state observer is as follows: Among them, is q the estimated error of the shaft DC disturbance extended state observer, is q the shaft current of the permanent magnet synchronous motor, is the observed value of is q the observed value of the shaft DC disturbance, is the reciprocal of the inductance of the permanent magnet synchronous motor, is q the shaft voltage of the permanent magnet synchronous motor, is q the known quantity of the shaft, and are the gains of the DC disturbance extended state observer, and the superscript represents the first derivative; The said q axial harmonic expansion state observer is as follows: Among them, is q the observation error of the n th harmonic extended state observer of the axis, is the observed value of is q the harmonic disturbance observed value of the th harmonic extended state observer of the axis, , when = 0, is q the DC disturbance observed value of the DC disturbance observer of the axis, is the number of harmonic extended state observers, is the gain of the harmonic extended state observer, is q the harmonic disturbance with frequency observed on the axis, and are auxiliary variables, and are auxiliary variables, and are auxiliary variables; Among them, is the notch bandwidth of the notch filter, is the notch depth of the notch filter; The d axial DC disturbance extended state observer is as follows: Among them, is d the estimated error of the shaft DC disturbance extended state observer, is the permanent magnet synchronous motor d shaft current, is the observed value of is d the observed value of the shaft DC disturbance, is the permanent magnet synchronous motor d shaft voltage, is d the known quantity of the shaft; The d axial harmonic expansion state observer is as follows: Among them, is d the observation error of the n th harmonic extended state observer of the axis, is the observed value of is d the observed value of the harmonic disturbance of the th harmonic extended state observer of the axis, , when = 0, is d the observed value of the DC disturbance of the DC disturbance observer of the axis, is the number of harmonic extended state observers, is d the harmonic disturbance with frequency observed on the axis, and are auxiliary variables, and are auxiliary variables, and are auxiliary variables; 。 2. The deadbeat predictive current control method based on an extended notch state observer according to claim 1, wherein In the above S2, when designing the deadbeat predictive current control method for a permanent magnet synchronous motor, the formula is: Among them, is the current, is the current control moment, is the next control moment, is the state matrix, is the input parameter, is the additional input quantity, is the input voltage, is the disturbance estimated value; Among them, is the control period, is the inductor, and are the shaft currents of the permanent magnet synchronous motor d and q respectively, and are the shaft voltages of the permanent magnet synchronous motor d and q respectively, and are respectively d and q the estimated values of shaft disturbances, is the resistance, is the electrical angular velocity, is the magnetic flux, and the superscript is the matrix transpose; It is considered that , the reference voltage is calculated as follows: Among them, is the reference input voltage, is the reference current, and are respectively d and q the x-axis reference input voltage, and are respectively d and q the y-axis reference input current; According to the reference voltage, make the predicted current equal to the reference input value to achieve predicted current control.

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