A kind of composite disturbance observer-based deadbeat predictive current control method

Abstract

The application discloses a kind of based on composite disturbance observer's no beat predictive current control method, belong to double three-phase permanent magnet motor control technical field.Double three-phase permanent magnet motor is constituted by two sets of stator three-phase winding, and space phase shift angle is 30 degrees.The method of the application includes: in double dq Coordinate system under the establishment of discrete motor model containing total disturbance;Design composite disturbance observer, which is through embedding the second-order disturbance expansion state observer of generalized integrator, synchronous estimation direct current disturbance and alternating current disturbance;Using disturbance estimation value carries out feedforward compensation, combined with no beat prediction calculation voltage control quantity.The application realizes the synchronous compensation of direct current disturbance and alternating current disturbance by introducing second-order disturbance expansion state observer and generalized integrator, to effectively reduce current harmonic, improve current waveform quality.Meanwhile, the application realizes the complete decoupling of current control loop and disturbance suppression loop.In addition, the application still shows strong robustness under motor parameter mismatch condition.

Description

Technical Field

[0001] This invention belongs to the field of high-performance permanent magnet motor control technology, specifically relating to a deadbeat predictive current control method based on a composite disturbance observer, used for current control of a dual three-phase permanent magnet motor drive system. Background Technology

[0002] Dual three-phase permanent magnet synchronous motors have become an ideal choice for high-reliability applications such as aerospace propulsion and electric power transportation due to their excellent torque output capability, good speed regulation performance, and outstanding fault tolerance characteristics. In dual three-phase permanent magnet synchronous motor control systems, deadbeat predictive current control is widely used due to its simple structure and fast dynamic response.

[0003] However, in practical applications, the high dependence of deadbeat predictive current control on the accuracy of the system model makes it susceptible to various disturbances, such as DC disturbances caused by parameter mismatch and AC disturbances caused by inverter nonlinearity and flux harmonics. The former may lead to current deviations or even system instability, while the latter will generate current harmonics, thus significantly reducing the control performance of the system.

[0004] In the control of dual three-phase permanent magnet motors, enhancing the system's anti-disturbance capability, improving system stability, reducing current harmonics, and improving the quality of current waveforms are urgent problems to be solved. Summary of the Invention

[0005] To address this, the present invention provides a deadbeat predictive current control method based on a composite disturbance observer for high-performance current control of a dual three-phase permanent magnet synchronous motor drive system. This method achieves synchronous compensation for DC and AC disturbances through a second-order disturbance extended state observer and a generalized integrator, effectively reducing current harmonics and enhancing the stability of the dual three-phase permanent magnet synchronous motor control system. Furthermore, this method exhibits strong robustness under motor parameter mismatch conditions.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention first provides a deadbeat predictive current control method based on a composite disturbance observer for current control of a dual three-phase permanent magnet motor drive system. The method includes the following steps:

[0008] 1) Establish a discretized prediction model for a dual three-phase permanent magnet motor in a dual dq coordinate system; and define a total disturbance term in the model that includes DC disturbance components and AC disturbance components;

[0009] 2) Design a composite disturbance observer, which includes an extended state observer module for observing the DC disturbance component and a generalized integrator module for observing the AC disturbance component; the generalized integrator module is embedded within the framework of the extended state observer module to simultaneously estimate the DC disturbance and the AC disturbance; the extended state observer module is a second-order disturbance extended state observer, which observes the DC disturbance component and its first derivative as an extended state;

[0010] 3) In each control cycle, the current and speed of the motor at the current moment are collected, and the total disturbance estimate at the next moment is obtained using the composite disturbance observer;

[0011] 4) Based on the discretized prediction model, the current reference value, the current and speed at the current moment, and the total disturbance estimate, calculate the predicted voltage control quantity for the next moment;

[0012] 5) The predicted voltage control quantity is modulated and applied to the inverter to drive the dual three-phase permanent magnet synchronous motor, thereby realizing deadbeat predictive current control of the dual three-phase permanent magnet motor based on the composite disturbance observer.

[0013] The beneficial effects of this invention include:

[0014] The deadbeat predictive current control method based on a composite disturbance observer provided by this invention employs a second-order disturbance extended state observer and a generalized integrator to suppress DC and AC disturbances respectively. This not only effectively eliminates current harmonics but also exhibits strong robustness against motor parameter mismatch. Furthermore, this invention enables complete decoupling between the current control loop and the disturbance suppression loop. Attached Figure Description

[0015] Figure 1 This is a flowchart of the deadbeat predictive current control method based on a composite disturbance observer according to the present invention.

[0016] Figure 2 This is the topology diagram of the drive circuit for a dual three-phase permanent magnet synchronous motor.

[0017] Figure 3 The results are experimental findings of the traditional deadbeat predictive current control method based on an extended state observer under rated load torque.

[0018] Figure 4 The results are experimental results of the method of the present invention under rated load torque.

[0019] Figure 5 This presents experimental results of the traditional deadbeat predictive current control method based on an extended state observer under inductor parameter mismatch conditions.

[0020] Figure 6The results are experimental findings of the method of the present invention under inductance parameter mismatch conditions. Detailed Implementation

[0021] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0022] like Figure 1 As shown in the figure, this invention proposes a deadbeat predictive current control method based on a composite disturbance observer for current control of a dual three-phase permanent magnet motor drive system, including the following steps:

[0023] 1) Establish a discretized prediction model for a dual three-phase permanent magnet motor in a dual dq coordinate system; and define a total disturbance term in the model that includes DC disturbance components and AC disturbance components;

[0024] 2) Design a composite disturbance observer, which includes an extended state observer module for observing the DC disturbance component and a generalized integrator module for observing the AC disturbance component; the generalized integrator module is embedded within the framework of the extended state observer module to simultaneously estimate the DC disturbance and the AC disturbance; the extended state observer module is a second-order disturbance extended state observer, which observes the DC disturbance component and its first derivative as an extended state;

[0025] 3) In each control cycle, the current and speed of the motor at the current moment are collected, and the total disturbance estimate at the next moment is obtained using the composite disturbance observer;

[0026] 4) Based on the discretized prediction model, the current reference value, the current and speed at the current moment, and the total disturbance estimate, calculate the predicted voltage control quantity for the next moment;

[0027] 5) The predicted voltage control quantity is modulated and applied to the inverter to drive the dual three-phase permanent magnet synchronous motor, thereby realizing deadbeat predictive current control of the dual three-phase permanent magnet motor based on the composite disturbance observer.

[0028] This invention addresses the problem that the accuracy of deadbeat predictive current control is easily affected by DC and AC disturbances. It achieves synchronous compensation for DC and AC disturbances through a second-order disturbance extended state observer and a generalized integrator. The drive circuit topology of the dual three-phase permanent magnet synchronous motor is shown below. Figure 2As shown. The motor adopts a double-Y structure, with a 30° phase difference between the two three-phase windings. Based on the motor's double three-phase configuration, the inverter consists of two parallel three-phase bridges, each employing a two-level topology. The inverter has a total of six phases, with each phase bridge arm composed of two IGBT or MOSFET switching devices.

[0029] The following provides a further explanation of each step of the present invention:

[0030] First, in this embodiment, step 1) specifically includes:

[0031] In the dual dq coordinate system, the continuous domain mathematical model of the dual three-phase permanent magnet synchronous motor can be expressed as:

[0032]

[0033] in, Stator resistance; and These represent the self-inductance along the d-axis and q-axis, respectively. and These represent the mutual inductance along the d-axis and q-axis, respectively. This refers to the rotor flux linkage amplitude; , , , These are the d-axis and q-axis currents of the first and second windings, respectively. , , , These are the d-axis and q-axis voltages of the first and second windings, respectively. Let be the electric angular velocity of the motor.

[0034] For ease of explanation, the above formula can be rewritten as:

[0035]

[0036] Where vector , , ;

[0037]

[0038]

[0039] The continuous-domain mathematical model of the rewritten dual three-phase permanent magnet synchronous motor is discretized. In this embodiment, the first-order forward Euler approximation is used:

[0040]

[0041] in It is the sampling period.

[0042] In a dual three-phase permanent magnet motor drive system, various disturbances can weaken the control performance of the current loop. These disturbances can generally be divided into two categories: DC disturbance components and AC disturbance components.

[0043] 1) DC disturbance component

[0044] The DC disturbance component is mainly caused by motor parameter mismatch, cross-coupling terms, and unmodeled DC dynamics, and can be expressed as follows:

[0045]

[0046] in , , It is a state vector that describes the flux linkage in a motor control system. It is a matrix that describes how the motor inductance affects the state and control variables of the current. and For the corresponding initial values, These are called the nominal values ​​of the input matrix. This is the feedforward compensation vector. and This is the parameter variation matrix; For the k-th sampling period, the unknown external disturbance components of the d1, q1, d2 and q2 axes are given.

[0047] 2) AC disturbance component

[0048] The AC disturbance components are caused by flux linkage harmonics and inverter nonlinearity, where the flux linkage harmonics can be expressed as:

[0049]

[0050] in , , and These are harmonics of the flux linkages along the d1, q1, d2, and q2 axes. , , and These are the amplitudes of the 6nth flux linkage harmonics along the d1, q1, d2, and q2 axes, respectively.

[0051] The nonlinearity of the inverter introduces significant voltage harmonics, which can be expressed as:

[0052]

[0053] in , , and These are the voltage harmonics along the d1, q1, d2, and q2 axes, respectively. It's dead time. It is DC voltage.

[0054] The AC disturbance in the kth sampling period can be expressed as:

[0055]

[0056] in , .

[0057] Therefore, the total disturbance of the system can be expressed as

[0058]

[0059] The discretized mathematical model of the two-phase three-phase permanent magnet motor, including the total disturbance term, is as follows:

[0060]

[0061] in Represents the feedforward compensation vector for the kth sampling period. .

[0062] Step 2) Design a composite disturbance observer. In this invention, the composite disturbance observer includes an extended state observer module for observing the DC disturbance component and a generalized integrator module for observing the AC disturbance component; the generalized integrator module is embedded within the framework of the extended state observer module to simultaneously estimate the DC disturbance and the AC disturbance; the extended state observer module is a second-order disturbance extended state observer, which observes the DC disturbance component and its first derivative as an extended state;

[0063] Step 2) includes:

[0064] 21) Establish an extended state-space model for a dual three-phase permanent magnet motor:

[0065] The DC disturbance component and its first derivative are regarded as extended state variables and introduced into the state space model of the motor. The extended state vector includes stator current, DC disturbance, the first derivative of DC disturbance and the second derivative of DC disturbance, thereby forming an extended state space model of the dual three-phase permanent magnet motor.

[0066] 22) Design a second-order perturbation extended state observer with an embedded generalized integrator:

[0067] The second-order disturbance extended state observer uses the stator current as the observation, predicts the current in the next sampling period based on the extended state space model, and uses the deviation between the predicted current and the actual current to correct the current estimate and disturbance estimate, thereby simultaneously obtaining the estimates of the total motor disturbance, DC disturbance and AC disturbance.

[0068] The total disturbance estimate is obtained by superimposing the DC disturbance estimate and the AC disturbance estimate; the DC disturbance and its first derivative estimate are obtained by superimposing a correction term proportional to the current estimation error on the basis of the state prediction; the AC disturbance estimate is generated by a generalized integrator with the current estimation error as input.

[0069] More specifically, in this embodiment, step 2) is implemented as follows:

[0070] a. Design a generalized integrator and discretize it.

[0071] The continuous-domain expression for the generalized integrator is:

[0072]

[0073] in For proportional gain, It is the resonant frequency.

[0074] The discrete-domain expression of the generalized integrator is:

[0075]

[0076] in , , , .

[0077] In a dual three-phase permanent magnet motor drive system, AC disturbances mainly manifest as the 6th harmonic component in the stator current. This harmonic causes electromagnetic torque pulsation and current waveform distortion. To suppress the aforementioned 6th harmonic AC disturbances, the resonant frequency of the designed generalized integrator is set to 6 times the fundamental frequency of the motor, thereby achieving selective amplification and precise compensation of the 6th harmonic component.

[0078] b. Treating the DC disturbance and its first derivative as an extended state, establish a state-space model for the dual three-phase permanent magnet motor.

[0079] Treating the DC disturbance and its first derivative as an extended state, the model of the dual three-phase permanent magnet motor can be expressed as follows:

[0080]

[0081] in and These represent the first and second derivatives of the DC disturbance, respectively.

[0082] c. Design a second-order perturbation extended state observer (i.e., a composite perturbation observer) with an embedded generalized integrator.

[0083] Generalized integrators can effectively compensate for AC disturbances. This invention embeds a generalized integrator into a disturbance observer to suppress AC disturbances. Therefore, the composite disturbance observer can be designed as follows:

[0084] in Indicates the estimated current. This represents the estimated total disturbance. This represents the estimated DC disturbance. This represents the estimated communication disturbance. , and This is the gain of the second-order perturbation extended state observer.

[0085] The second-order disturbance propagation state observer includes a first observer gain, a second observer gain, and a third observer gain. These gains are proportional to the first, second, and third powers of a preset observer bandwidth, respectively, to determine the observer's dynamic response speed and disturbance tracking capability based on the observer bandwidth. Specifically, the gain design is as follows:

[0086]

[0087] in It is the bandwidth of the second-order perturbation extended state observer.

[0088] Step 3) of the present invention mainly involves collecting the current and speed of the motor at the current moment, and using the composite disturbance observer described in step 2) to obtain the total disturbance estimate for the next moment;

[0089] Step 4 of the present invention is to calculate the predicted voltage control quantity for the next moment based on the discretized prediction model, the current reference value, the current and speed at the current moment, and the total disturbance estimate.

[0090] In step 4), the predicted voltage control quantity is designed as follows:

[0091] In the k-th sampling period, the reference stator current of the k-th sampling period is... The predicted value of the stator current in the (k+1)th sampling period The difference minus the sampling period Compared with the disturbance estimate The product of the two factors is divided by the sampling period and the nominal value of the input matrix. The product of these, plus the feedforward compensation vector of the kth sampling period. The value is used as the control voltage input for that sampling period. ;

[0092] Expressed as a formula:

[0093] Feedforward compensation vector All components except the second and fourth components are zero. The second and fourth components are equal to the electric angular velocity of the motor, respectively. With permanent magnet flux amplitude The product of is used for voltage feedforward compensation of the motor's back electromotive force.

[0094] The transfer function of the current loop in this invention can be expressed as:

[0095]

[0096] As shown in the above equation, the equivalent transfer function of the current control loop in the discrete domain is a pure delay element for two sampling periods, and this element has unity gain and contains no coefficients related to the disturbance observer. That is, the operation of the current loop is independent of the parameters of the disturbance observer. Therefore, in this invention, the current control loop and the disturbance suppression loop are completely decoupled.

[0097] Step 5 of the present invention is to apply the predicted voltage control quantity to the inverter after modulation to drive the dual three-phase permanent magnet synchronous motor, thereby realizing deadbeat predictive current control of the dual three-phase permanent magnet motor based on the composite disturbance observer.

[0098] The method of the present invention will be further described below with reference to a specific embodiment. The parameters of the dual three-phase permanent magnet motor and the controller parameters in the embodiment are shown in Table 1.

[0099] Table 1 shows the parameters of the dual three-phase permanent magnet motor and the controller used in the experiment.

[0100]

[0101] The deadbeat predictive current control method proposed in this invention is compared with the traditional deadbeat predictive current control method based on an extended state observer. For example... Figure 3 As shown, under rated load torque conditions, in the traditional deadbeat predictive current control method based on an extended state observer, i q1 and i q2 The sixth harmonics are 2.57% and 2.09% respectively, and the phase current i a with i u The THD levels were 2.78% and 2.36%, respectively. Figure 4In this invention, the method achieves lower harmonic content, i q1 and i q2 The sixth harmonic was reduced to 0.29% and 0.22% respectively, and the phase current i a with i u The THD was reduced to 0.96% and 0.77%, respectively. The current harmonic suppression capability of the method proposed in this invention is superior to that of the traditional deadbeat predictive current control method based on the extended state observer. Figure 5 Corresponding to the traditional deadbeat predictive current control method based on extended state observers, when the inductor parameters change, i d and i q Significant fluctuations were observed in the current. Although traditional deadbeat predictive current control methods have some robustness to DC disturbances, they remain quite sensitive to AC disturbances. Figure 6 In this invention, the method exhibits superior control performance, especially during changes in inductance parameters. d and i q The current remains stable throughout. Its dynamic performance is minimally affected, and all current deviations and harmonic components are effectively compensated. Therefore, the method proposed in this invention exhibits excellent robustness to both DC and AC disturbances.

[0102] In summary, the method proposed in this invention effectively eliminates current harmonics and improves the quality of the current waveform by employing a second-order disturbance extended state observer and a generalized integrator to suppress DC and AC disturbances, respectively. Simultaneously, the design of the second-order disturbance extended state observer avoids the use of motor parameters, improving the robustness of the system. The proposed method achieves complete decoupling between the current control loop and the disturbance suppression loop. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.

Claims

1. A deadbeat predictive current control method based on a composite disturbance observer, used for current control of a dual three-phase permanent magnet synchronous motor drive system, characterized in that, The method includes the following steps: 1) Establish a discretized prediction model for a dual three-phase permanent magnet synchronous motor in a dual dq coordinate system; and define a total disturbance term in the model that includes DC disturbance components and AC disturbance components; 2) Design a composite disturbance observer, which includes an extended state observer module for observing the DC disturbance component and a generalized integrator module for observing the AC disturbance component; the generalized integrator module is embedded within the framework of the extended state observer module to simultaneously estimate the DC disturbance and the AC disturbance; the extended state observer module is a second-order disturbance extended state observer, which observes the DC disturbance component and its first derivative as an extended state; 3) In each control cycle, the current and speed of the motor at the current moment are collected, and the total disturbance estimate at the next moment is obtained using the composite disturbance observer; 4) Based on the discretized prediction model, the current reference value, the current and speed at the current moment, and the total disturbance estimate, calculate the predicted voltage control quantity for the next moment; The predicted voltage control quantity is designed as follows: In the k-th sampling period, the reference stator current of the k-th sampling period is... The predicted value of the stator current in the (k+1)th sampling period The difference minus the sampling period Compared with the disturbance estimate The product of the two factors is divided by the sampling period and the nominal value of the input matrix. The product of these, plus the feedforward compensation vector of the kth sampling period. The value is used as the control voltage input for that sampling period. ; The calculation formula is: ; Among them, the feedforward compensation vector All components except the second and fourth components are zero. The second and fourth components are equal to the electric angular velocity of the motor, respectively. With permanent magnet flux amplitude The product of is used for voltage feedforward compensation of the motor's back electromotive force; 5) The predicted voltage control quantity is modulated and applied to the inverter to drive the dual three-phase permanent magnet synchronous motor, thereby realizing deadbeat predictive current control of the dual three-phase permanent magnet synchronous motor based on the composite disturbance observer.

2. The method according to claim 1, characterized in that, In step 1), the DC disturbance component is caused by motor parameter mismatch, cross-coupling terms, and DC dynamics that are not explicitly modeled; the AC disturbance component is caused by flux harmonics and inverter nonlinearity.

3. The method according to claim 1, characterized in that, Step 2) involves designing a composite disturbance observer, including establishing an extended state-space model of the dual three-phase permanent magnet synchronous motor: The DC disturbance component and its first derivative are regarded as extended state variables and introduced into the state space model of the motor. The extended state vector includes stator current, DC disturbance, the first derivative of DC disturbance and the second derivative of DC disturbance, thereby forming an extended state space model of the dual three-phase permanent magnet synchronous motor.

4. The method according to claim 3, characterized in that, Step 2) involves designing a composite perturbation observer, which further includes designing a second-order perturbation extended state observer embedded with a generalized integrator: The second-order disturbance extended state observer uses the stator current as the observation, predicts the current in the next sampling period based on the extended state space model, and uses the deviation between the predicted current and the actual current to correct the current estimate and disturbance estimate, thereby simultaneously obtaining the estimates of the total motor disturbance, DC disturbance and AC disturbance. The total disturbance estimate is obtained by superimposing the DC disturbance estimate and the AC disturbance estimate; the DC disturbance and its first derivative estimate are obtained by superimposing a correction term proportional to the current estimation error on the basis of the state prediction; the AC disturbance estimate is generated by a generalized integrator with the current estimation error as input.

5. The method according to claim 4, characterized in that, The second-order disturbance spread state observer is provided with a first observer gain, a second observer gain, and a third observer gain; the first observer gain, the second observer gain, and the third observer gain are respectively proportional to the first power, the second power, and the third power of a preset observer bandwidth, so as to determine the dynamic response speed and disturbance tracking capability of the observer based on the observer bandwidth.

6. The method according to claim 1, characterized in that, The generalized integrator module is a discrete quasi-resonant controller, whose resonant frequency is set to 6 times the fundamental frequency of the dual three-phase permanent magnet synchronous motor, so as to achieve selective amplification and precise compensation of the 6th harmonic component.

7. The method according to claim 1, characterized in that, The design of the composite disturbance observer makes the closed-loop transfer function of the current control loop independent of the parameters of the composite disturbance observer, thereby achieving decoupling between the current control loop and the disturbance suppression loop.

8. The method according to claim 7, characterized in that, The equivalent transfer function of the current control loop in the discrete domain is a pure delay element for two sampling periods, and this element has unity gain and contains no coefficients related to the disturbance observer.

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