Design method of model-free rotating speed controller of ship propulsion permanent magnet motor

Abstract

The invention discloses a method for designing a model-free rotating speed controller of a ship propulsion permanent magnet motor, which comprises the following steps of: 1, deducing a motor motion state equation by considering torque pulsation caused by current measurement error and the like; 2, designing a model-free rotating speed controller based on the motor super-local model; 3, designing an error-based extended state observer, estimating lumped disturbance of the system and performing real-time compensation; and 4, introducing a repetitive controller to improve the estimation precision of the periodic disturbance. The method is simple in step, the estimation performance of the system on periodic and non-periodic disturbance is enhanced, and the steady-state rotating speed precision and the dynamic response speed of the system are improved.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and more specifically, particularly relates to a design method for a model-free speed controller of a ship propulsion permanent magnet motor. Background Technique

[0002] Permanent magnet synchronous motors have advantages such as high power density, high efficiency, and high power factor, and have been widely used in fields such as ship propulsion, new energy vehicles, and rail transit. The vector control system of permanent magnet synchronous motors mainly includes speed loop and current loop control, and the speed loop control directly determines the operating performance of the system.

[0003] At present, PI controllers are widely used due to advantages such as simple algorithms and easy implementation; however, in actual control systems, uncertain factors such as parameter perturbations and external disturbances will greatly affect the control system of the system, and PI control cannot suppress these disturbances. In order to reduce the dependence of the control system on the motor model, model-free control has been widely used in motor control in recent years. However, the control performance of model-free control directly depends on the estimation accuracy of the lumped disturbance of the system.

[0004] Most existing disturbance observers mainly observe non-periodic disturbances including load disturbances and parameter perturbations, but none of them can accurately estimate the periodic disturbance amount; and in actual control systems, due to factors such as current measurement errors, flux linkages harmonics, and inverter nonlinearities, there are periodic torque pulsations. Therefore, it is necessary to use a disturbance observer to estimate both non-periodic and periodic disturbance amounts simultaneously, so as to achieve accurate compensation for the lumped disturbance. Summary of the Invention

[0005] The purpose of the present invention is to provide a design method for a cascaded active disturbance rejection speed controller of a ship propulsion permanent magnet motor for the application background of low speed and high torque in the ship propulsion field, enhance the system's ability to resist load disturbances and parameter changes, and improve the robustness of the system.

[0006] To solve the above technical problems, the present invention adopts a design method for a model-free speed controller of a ship propulsion permanent magnet motor, including the following steps:

[0007] Step 1: In the double closed-loop vector control of the permanent magnet synchronous motor, considering the torque pulsation caused by current measurement errors, etc., derive the motor motion state equation;

[0008] Step 2: Based on the motor's ultra-local model, design a model-free speed controller;

[0009] Step 3: Design an extended state observer based on the error to estimate the lumped disturbance in the system and compensate it into the speed controller;

[0010] Step 4: Introduce a repetitive controller into the extended state observer based on error to improve the estimation accuracy of periodic disturbances.

[0011] Further, the specific content of Step 1 is as follows:

[0012] Considering the torque ripple caused by current measurement error, the motion equation of the motor can be expressed as:

[0013]

[0014] where ω m represents the mechanical angular velocity of the motor, J represents the moment of inertia of the motor, T L represents the load torque of the motor, B is the damping coefficient of the motor, and b is the control coefficient, expressed as:

[0015]

[0016] n p represents the number of pole pairs of the motor, ψ f represents the permanent magnet flux linkage of the motor, i q represents the quadrature-axis current of the motor. T harm1 and T harm2 are the torque ripples caused by current offset error and current scaling error respectively, and can be expressed as:

[0017]

[0018] where △ I a and △ I b are the DC offset amounts of the A-phase and B-phase currents respectively, K a and K b are the scaling coefficients of the A-phase and B-phase currents respectively, δ is the angle difference caused by the A-phase and B-phase current offset amounts, and θ e is the electrical angle value of the motor.

[0019] Further, the speed controller designed based on the super-twisting model in Step 2 is designed as:

[0020]

[0021] where ω m * represents the given mechanical angular velocity of the motor, i q * represents the given value of the quadrature-axis current, K p is the proportional coefficient of the controller, is the estimated disturbance value.

[0022] Further, the specific content of Step 3 is as follows:

[0023] Based on the ultra-local model, the motor motion state equation can be further expressed as:

[0024]

[0025] where, e ω is the difference between the given speed and the actual speed of the motor, b0 is the nominal value of parameter b, and f r is the reconstructed value of the lumped error.

[0026] Based on the motor speed error, a linear extended state observer is designed as:

[0027]

[0028] where, L1 and L2 are the gain coefficients of the linear extended state observer, is the estimated value of the lumped error.

[0029] To further improve the estimation accuracy of the observer for periodic disturbances, a repetitive controller is introduced into the extended state observer, which can be expressed as:

[0030]

[0031] where, and are the estimated values of the non-periodic disturbance and the periodic disturbance respectively. G rc1 and G rc2 are the repetitive controllers, which can be expressed as:

[0032]

[0033] where, k rc is the control gain, Q(z) is the low-pass filter, and C(z) is the phase compensator. z -N represents the delay link, where N = (2π / ω h ) / T s , ω h1 and ω h2 are set to 1 times and 2 times the angular velocity of the motor respectively to estimate the 1-time and 2-time frequency speed fluctuations caused by the current measurement error.

[0034] The present invention has the following advantages compared with the prior art:

[0035] 1. In the design process of the model-free speed controller for a ship propulsion permanent magnet motor, considering that the motor in the actual system is frequently affected by periodic and aperiodic disturbances, the periodic torque ripple caused by current measurement errors is analyzed, the motion state equation of the motor under complex disturbances is derived, and a model-free speed controller is adopted to improve the robustness of the controller. An extended state observer based on speed error is designed to estimate the lumped disturbance of the system in real time and compensate it into the speed controller in real time. A repetitive controller is introduced to estimate the periodic disturbance quantity, improve the estimation accuracy of the observer for periodic and aperiodic disturbances, and further enhance the disturbance rejection ability of the model-free speed controller.

[0036] 2. Through the prototype experimental platform of the permanent magnet synchronous motor, the vector control of the ship propulsion permanent magnet motor based on the model-free speed controller proposed in this invention is experimentally verified under different working conditions. The results show that the lumped disturbance of the system can be accurately estimated under different working conditions, the steady-state speed fluctuation of the motor can be greatly reduced, and the dynamic control performance of the motor can be improved.

[0037] 3. The method steps of this invention are simple, and greatly enhance the robustness of the system under complex disturbances.

[0038] The technical solution of this invention will be further described in detail below through the accompanying drawings and embodiments. Description of the Drawings

[0039] Figure 1 is the structural block diagram of the vector control system of the ship propulsion permanent magnet motor of this invention;

[0040] Figure 2 is the steady-state speed waveform and speed Fourier transform diagram of the motor based on the PI speed controller in the embodiment of this invention;

[0041] Figure 3 is the steady-state speed waveform and speed Fourier transform diagram of the motor based on the model-free speed controller in the embodiment of this invention;

[0042] Figure 4 is the waveform diagram of the motor based on the PI speed controller when a sudden load is applied in the embodiment of this invention;

[0043] Figure 5 is the waveform diagram of the motor based on the model-free speed controller when a sudden load is applied in the embodiment of this invention. Detailed Embodiment

[0044] The design method of the cascaded active disturbance rejection speed controller for the ship propulsion permanent magnet motor of this invention includes the following steps:

[0045] To solve the above technical problems, this invention adopts a design method of a model-free speed controller for a ship propulsion permanent magnet motor, including the following steps:

[0046] Step 1: In the double closed-loop vector control of a permanent magnet synchronous motor, considering the torque ripple caused by current measurement errors, etc., deduce the motor motion state equation;

[0047] Step 2: Design a model-free speed controller based on the motor's super-local model;

[0048] Step 3: Design an extended state observer based on error to estimate the lumped disturbance in the system and compensate it into the speed controller;

[0049] Step 4: Introduce a repetitive controller into the extended state observer based on error to improve the estimation accuracy of periodic disturbances.

[0050] Considering the torque ripple caused by current measurement errors, the motion equation of the motor can be expressed as:

[0051]

[0052] where, ω m represents the mechanical angular velocity of the motor, J represents the moment of inertia of the motor, T L represents the load torque of the motor, and B is the damping coefficient of the motor. Among them,

[0053]

[0054] n p represents the number of pole pairs of the motor, ψ f represents the permanent magnet flux linkage of the motor, i q represents the quadrature-axis current of the motor. T harm1 and T harm2 are the torque ripples caused by current offset error and current scaling error respectively, and can be expressed as:

[0055]

[0056] where, △ I a and △ I b are the DC offset amounts of the A-phase and B-phase currents respectively, K a and K b are the scaling coefficients of the A-phase and B-phase currents respectively, δ is the angle difference caused by the A-phase and B-phase current offset amounts, and θ e is the electrical angle value of the motor.

[0057] The speed controller designed based on the super-local model can be designed as:

[0058] where, ω m * represents the given mechanical angular velocity of the motor, i q* represents the quadrature-axis current reference value, K p is the proportional coefficient of the controller, is the estimated disturbance value.

[0059] Based on the super-local model, the motor motion state equation can be further expressed as:

[0060]

[0061] where, e ω is the difference between the motor reference speed and the actual speed, b0 is the nominal value of parameter b, f r is the reconstructed value of the lumped error.

[0062] Based on the motor speed error, a linear extended state observer based on the error can be designed as:

[0063]

[0064] where, L1 and L2 are the gain coefficients of the linear extended state observer, is the estimated value of the lumped error.

[0065] To further improve the estimation accuracy of the observer for periodic disturbances, a repetitive controller is introduced into the extended state observer, which can be expressed as:

[0066]

[0067] where, and are the estimated values of the non-periodic disturbance and the periodic disturbance respectively. G rc1 and G rc2 are the repetitive controllers, which can be expressed as:

[0068]

[0069] where, k rc is the control gain, Q(z) is the low-pass filter, and C(z) is the phase compensator. z -N represents the delay link, where N = (2π / ω h ) / T s , ω h1 and ω h2 are set to 1 times and 2 times the motor angular velocity respectively to estimate the 1 times and 2 times frequency speed fluctuations caused by the current measurement error.

[0070] To verify the performance of the permanent magnet motor vector control system based on the model-free speed controller, experimental verification under different working conditions was carried out on the experimental platform based on the permanent magnet synchronous prototype. The parameters of the permanent magnet motor prototype are as follows: the number of pole pairs is 5, the rated speed is 300 r / min, the direct and quadrature axis inductances are 3.2591 mH, the stator resistance is 0.3285 Ω, the permanent magnet flux linkage is 0.3874 Wb, and the moment of inertia is 0.03072 kg·m 2 , and the rated load is 61.6 N·m; the PWM switching frequency is set to 10 kHz, and the sampling frequency is set to 10 kHz.

[0071] To verify the performance of the permanent magnet motor vector control system based on the model-free speed controller, the system performance under the steady-state operation of the motor and load mutation was compared and analyzed respectively. Figure 2 and Figure 3 are respectively the steady-state speed of the motor and the corresponding speed Fourier transform diagrams based on the PI controller and the model-free speed controller. The experimental working conditions are set as follows: the given speed is 60 r / min and the motor runs no-load. From Figure 2 's speed response waveform, it can be seen that: the steady-state speed fluctuation of the motor is 10.4 r / min, and the proportions of the fundamental frequency and the second harmonic in its speed fluctuation are 5.05% and 2.29% respectively. The steady-state speed fluctuation based on the model-free speed controller is 6.4 r / min, which is 38.5% smaller than that of the PI controller. At the same time, the proportions of the fundamental frequency and the second harmonic in the speed fluctuation also decrease to 2.56% and 0.55%.

[0072] Figure 4 and Figure 5 are respectively the waveforms based on the PI controller and the model-free speed controller when the load is suddenly increased, including the given speed waveform, the actual speed waveform, the q-axis current waveform, and the A-phase current waveform. The experimental working conditions are set as follows: the speed is 60 r / min and the motor runs no-load. After running for 2 s, a 50% rated load is suddenly applied. From Figure 4 it can be seen that after the load is suddenly increased, the motor speed drops sharply to 6.9 r / min, and it takes about 5.25 s for the motor to run stably again at 60 r / min, and the steady-state speed fluctuation is 13 r / min; while using the model-free speed controller, the drop value of the motor speed after the load is suddenly increased is only 21.8 r / min, and it can recover stability again after 0.4 s, and the steady-state speed fluctuation is 6 r / min.

[0073] Therefore, the system based on the model-free speed controller can accurately estimate the periodic disturbance quantity, thus greatly reducing the steady-state speed fluctuation of the motor and greatly improving the dynamic response performance of the motor at the same time.

[0074] In summary, the present invention designs a model-free speed controller based on an extended state observer, uses a linear extended state observer to estimate the lumped disturbance value in real time, and introduces a repetitive controller to achieve accurate estimation of periodic disturbances, thereby constructing a vector control system for a permanent magnet motor for ship propulsion. Experimental verification under different working conditions shows that the present invention can effectively improve the steady-state speed performance and dynamic response speed of the motor.

[0075] The above are only the preferred embodiments of the present invention and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent structural changes made to the above embodiments based on the essence of the present invention's technology still fall within the protection scope of the present invention's technical solution.

Claims

1. A design method for a model-free speed controller of a ship propulsion permanent magnet motor, characterized in that, It includes the following steps: Step 1: In the double-closed-loop vector control of a permanent magnet synchronous motor, considering the torque ripple caused by current measurement errors, etc., derive the motor motion state equation; Step 2: Design a model-free speed controller based on the motor's super-local model; Step 3: Design an error-based extended state observer to estimate the lumped disturbance in the system and compensate it into the speed controller; Step 4: Introduce a repetitive controller into the error-based extended state observer to improve the estimation accuracy of periodic disturbances.

2. The design method of the model-free speed controller for a ship propulsion permanent magnet motor according to claim 1, characterized in that: Specifically, the said Step 1 is as follows: Considering the torque ripple caused by current measurement errors, the motion equation of the motor can be expressed as: Among them, ω m represents the mechanical angular velocity of the motor, J represents the moment of inertia of the motor, T L represents the load torque of the motor, B is the damping coefficient of the motor, b is the control coefficient, expressed as: n p represents the number of pole pairs of the motor, ψ f represents the permanent magnet flux linkage of the motor, i q represents the quadrature-axis current of the motor. T harm1 and T harm2 are the torque ripples caused by the current bias error and the current scaling error respectively, expressed as: Among them, △ I a and △ I b are respectively the DC bias amounts of the phase-A and phase-B currents, K a and K b are respectively the scaling factors of the phase-A and phase-B currents, δ is the angle difference caused by the bias amounts of the phase-A and phase-B currents, and θ e is the electrical angle value of the motor.

3. The design method of the model-free speed controller for a marine propulsion permanent magnet motor according to claim 1, characterized in that: Specifically, the said Step 2 is as follows: The speed controller designed based on the super-local model is: Among them, ω m * represents the given mechanical angular velocity of the motor, and i q * represents the given value of the quadrature-axis current, and K p is the proportional coefficient of the controller, is the estimated disturbance value.

4. The design method of the model-free speed controller for a ship propulsion permanent magnet motor according to claim 1, characterized in that: Specifically, the said Step 3 is as follows: S31 Based on the super-local model, further express the motor motion state equation as: where, e ω is the difference between the motor's given speed and the actual speed, b0 is the nominal value of parameter b, f r is the reconstructed value of the lumped error; S32 Based on the motor speed error, design an error-based linear extended state observer as: where, L1 and L2 are the gain coefficients of the linear extended state observer, is the estimated value of the lumped error reconstruction value.

5. The design method of the model-free speed controller for a marine propulsion permanent magnet motor according to claim 1, characterized in that: Specifically, the said Step 4 is as follows: Adopt a repetitive controller to improve the estimation accuracy of periodic disturbances, and the error-based extended state observer is expressed as: Among them, and are the estimated values of the non-periodic disturbance and the periodic disturbance respectively; G rc1 and G rc2 are repetitive controllers, expressed as: Among them, k rc is the control gain, Q(z) is the low-pass filter, and C(z) is the phase compensator. z -N represents the delay link, where N = (2π / ω h ) / T s , ω h1 and ω h2 are respectively set as the multiple values of the motor angular velocity.

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