Reference adaptive position-free control method for ship propulsion permanent magnet motor model

Abstract

The invention discloses a ship propulsion permanent magnet motor model reference adaptive position-free control method, which belongs to the field of motor control systems, and comprises the following steps: 1, estimating a system disturbance quantity based on an extended state observer of a quasi-resonance observer; 2, constructing a reference model and an adjustable model of permanent magnet motor position-free control based on a model reference adaptive method of stator current; 3, designing a self-adaptive law of the rotating speed of the motor based on super-spiral sliding mode control; and 4, applying the identified rotating speed and position signals to closed-loop vector control of the motor, and performing experimental verification based on a permanent magnet motor prototype experimental platform. According to the method, the system disturbance is estimated in real time by adopting the extended state observer, so that the motor model is more accurate, and the identification precision of the rotor position is improved.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and more specifically, to a model reference adaptive position-free control method for a ship propulsion permanent magnet motor based on an improved extended state observer. Background Art

[0002] Electric propulsion systems have a series of well-proven advantages, including superior dynamic performance, flexible motor installation, low fuel consumption and high ride comfort. Shaftless rim thrusters are a new type of ship propulsion method that combines motors and propellers into one, with the advantages of small size and weight, high propulsion efficiency, low vibration and noise, and high space utilization.

[0003] Compared with induction motors and reluctance motors, permanent magnet synchronous motors using high magnetic energy product rare earth permanent magnet excitation have advantages such as high power density, high efficiency, and high power factor. They are easier to achieve large electromagnetic air gaps and multi-pole structures, and are very suitable for the design requirements of "large outer diameter and thin" motors in the compact and special space of rim thrusters. However, permanent magnet motor vector control requires motor rotor position and speed information to achieve closed-loop control, and shaftless rim thrusters cannot be equipped with mechanical position sensors, so high-performance, high-precision position-free control algorithms are required to observe the motor rotor position in real time.

[0004] The position-free control method based on the motor model mainly realizes position observation through the motor back electromotive force, but due to its low signal-to-noise ratio at low speed, it is not suitable for low-speed and high-torque applications; the position-free control method based on the motor salient polarity mainly realizes rotor position observation by injecting high-frequency signals, which is suitable for zero-speed and low-speed applications, but it will produce large high-frequency noise. Generally, these two methods are combined to realize the position-free control of the motor in the full speed range, but the frequent switching process in the middle is prone to cause oscillation, so a position-free control method is required in the full speed range. To this end, a model reference adaptive position-free control method for ship propulsion permanent magnet motor based on an improved extended state observer is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a model reference adaptive positionless control method for ship propulsion permanent magnet motor based on an improved extended state observer, aiming at the application background of low speed and high torque in the field of ship propulsion, to enhance the system's positionless estimation performance under frequent speed changes and large load disturbances, and to improve the control robustness of the system.

[0006] In order to solve the above technical problems, the present invention adopts a model reference adaptive position-free control method for a ship propulsion permanent magnet motor, which is characterized by comprising the following steps:

[0007] Step 1: Introduce a quasi-resonant controller into the linear extended state observer to improve the estimation accuracy of periodic disturbances;

[0008] Step 2: Based on the model reference adaptive method of stator current, a reference model and an adjustable model of permanent magnet motor position-free control are constructed, and the output signals of the two are used to design an adaptive law to estimate the motor rotor speed and position information, and the observed information is fed back to the adjustable model in real time to realize dynamic identification of the rotor position signal;

[0009] Step 3: Introduce sliding mode control to replace the PI-based adaptive law, and use the super-helical sliding mode algorithm to further reduce the chattering of the sliding mode control and improve the robustness of speed identification;

[0010] Step 4: Use the identified speed and position signals for closed-loop vector control of the motor and conduct experimental verification of the system.

[0011] Furthermore, the step 1 is specifically as follows:

[0012] The quasi-resonant controller is introduced into the linear extended state observer and is designed as follows:

[0013]

[0014]

[0015] where i d 、i q is the motor dq axis current, u d 、u q is the motor dq axis voltage, L d , L q is the motor dq axis inductance, R s is the stator resistance of the motor, f d 、f q is the disturbance signal, the estimated signal is represented by the symbol ^, e d 、e q is the estimated difference of dq axis current, p is the differential operator, β1 and β2 are the observation gain values ​​of the extended state observer, ω c and k r are the resonant bandwidth and resonant coefficient of the quasi-resonant observer, ω e is the motor rotor angular velocity, y dq 、x dq and g dq are different intermediate variables of the observer in the dq axis.

[0016] Furthermore, the step 2 is specifically as follows:

[0017] The motor stator current equation can be expressed as:

[0018]

[0019] where i'd =i d +ψ f / L d ,i' q =i q ,u' d =u d +R s ψ f / L d ,u' q =u q , ψ f is the permanent magnet flux value of the motor.

[0020] The adjustable model can be designed as:

[0021]

[0022] Furthermore, the step three is specifically as follows:

[0023] The sliding surface can be designed as:

[0024]

[0025] The identified speed can be expressed as:

[0026]

[0027] where k p , k i are the proportional and integral coefficients of the adaptive law, sigmoid() is the S-type function, ω ref is the given motor angular velocity.

[0028] Furthermore, in step four, the position-free control algorithm is experimentally verified under different working conditions based on the permanent magnet motor prototype experimental platform.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1. In the process of designing the position-free control of the ship propulsion permanent magnet motor, the present invention combines the actual working conditions of low-speed, high-torque and frequent speed changes of ships, and uses the model reference adaptive method based on stator current to realize the position-free control of the motor in the full speed range. In view of the problem of poor performance of position-free control under nonlinear factors and complex working conditions, an extended state observer based on a quasi-resonant observer is used to achieve accurate estimation of periodic and non-periodic disturbances; an adaptive law based on super-helical sliding mode is designed, and an adaptive control coefficient is used to improve the robustness of position estimation performance under different loads and speeds.

[0031] 2. The present invention uses a permanent magnet motor prototype experimental platform to experimentally verify the proposed ship propulsion permanent magnet motor model reference adaptive position-free control method based on an improved extended state observer under different speed and load conditions. The results show that it has good speed and position estimation performance under different conditions.

[0032] 3. The method of the present invention has simple steps and greatly enhances the system's position-free control robustness under conditions of large load disturbance and frequent speed changes in ship propulsion. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a structural block diagram of the model reference adaptive position-free control of a ship propulsion permanent magnet motor based on an improved extended state observer of the present invention;

[0034] Figure 2 It is a structural block diagram of an extended state observer based on a quasi-resonant observer in the present invention;

[0035] Figure 3 The motor experimental waveform when running at no load in the embodiment of the present invention;

[0036] Figure 4 This is the experimental waveform of the motor when running at full load in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The present invention provides a technical solution: a model reference adaptive position-free control method for a ship propulsion permanent magnet motor based on an improved extended state observer, comprising the following steps:

[0038] Step 1: Introduce a quasi-resonant controller into the linear extended state observer to improve the estimation accuracy of periodic disturbances;

[0039] Step 2: Based on the model reference adaptive method of stator current, a reference model and an adjustable model of permanent magnet motor position-free control are constructed, and the output signals of the two are used to design an adaptive law to estimate the motor rotor speed and position information, and the observed information is fed back to the adjustable model in real time to realize dynamic identification of the rotor position signal;

[0040] Step 3: Introduce sliding mode control to replace the PI-based adaptive law, and use the super-helical sliding mode algorithm to further reduce the chattering of the sliding mode control and improve the robustness of speed identification;

[0041] Step 4: Use the identified speed and position signals for closed-loop vector control of the motor and conduct experimental verification of the system.

[0042] The present invention is based on the improved extended state observer model reference adaptive position-free control of ship propulsion permanent magnet motor. The overall control block diagram is shown in the appendix of the specification. Figure 1 shown.

[0043] The current equation of the permanent magnet motor in the dq coordinate system is:

[0044]

[0045] In the formula, i d 、i q is the motor dq axis current, u d 、u q is the motor dq axis voltage, L d , L q is the motor dq axis inductance, R s is the stator resistance of the motor, ψ f is the permanent magnet flux value of the motor, ω e is the motor angular velocity, and p is the differential operator.

[0046] It can be further rewritten as:

[0047]

[0048] Where i' d =i d +ψ f / L d ,i' q =i q ,u' d =u d +R s ψ f / L d ,u' q =u q .

[0049] In actual operation, due to the influence of nonlinear factors such as motor parameter perturbation and dead time, the motor stator current equation can be expressed as:

[0050]

[0051] In the formula, f d 、f q is the disturbance of the motor dq axis.

[0052] The adjustable model can be designed as:

[0053]

[0054] In the formula, the symbol “^” represents the corresponding estimated signal quantity.

[0055] The extended state observer is used to estimate the total disturbance of the system in real time, which can be expressed as:

[0056]

[0057] Where β1 and β2 are the observation gain values ​​of the extended state observer (β1 = 2ω, β2 = ω 2 ), ω is the bandwidth of the extended state observer.

[0058] In order to improve the estimation accuracy of periodic disturbance, a quasi-resonant observer is introduced, which is expressed as:

[0059]

[0060]

[0061] where e d 、e q is the estimated difference of dq axis current, ω c and k r are the resonant bandwidth and resonant coefficient of the quasi-resonant observer, respectively, dq 、x dq and g dq are different intermediate variables of the observer in the dq axis.

[0062] Based on Popov's hyperstability theory, a PI-based speed adaptive law can be constructed:

[0063]

[0064] However, due to the linear structure and bandwidth of PI control, the estimation performance is poor under complex and changeable actual working conditions. The present invention introduces sliding mode control and uses a super-helical sliding mode algorithm to further suppress system chattering. Its basic form is:

[0065]

[0066] Where s and u are system state variables, k1 and k2 are sliding mode gain values, and sign() represents the sign function.

[0067] The sliding surface can be designed as:

[0068]

[0069] The speed estimation expression based on super-helical sliding mode is obtained as follows:

[0070]

[0071] In order to further suppress system chattering, the sigmoid function is used instead of the sign function, and its expression is:

[0072] F(x)=2 / (1+e -ax )-1(1-13)

[0073] Where a is the adjustable parameter of the function.

[0074] In order to make the dynamic curve smoother without affecting the speed convergence speed, an adaptive coefficient is added before equation (1-12), and the corresponding speed estimation expression is:

[0075]

[0076] In the formula, - ref is the given motor angular velocity.

[0077] By integrating equation (1-14), we can get the estimated value of the rotor position:

[0078]

[0079] In order to verify the performance of the model reference adaptive position-free control method for ship propulsion permanent magnet motor based on the improved extended state observer, experimental verification under different working conditions was carried out on the experimental platform based on the permanent magnet synchronous motor prototype. The parameters of the permanent magnet motor prototype are: the number of pole pairs is 5, the rated speed is 300rpm, the AC and DC axis inductance is 3.2591mH, the stator resistance is 0.3285Ω, the permanent magnet flux is 0.3874Wb, and the moment of inertia is 0.03072kg·m 2 , the rated load is 61.6N·m; the PWM switching frequency is set to 10kHz, and the sampling frequency is set to 10kHz.

[0080] In order to verify the performance of the model reference adaptive position-free control method for ship propulsion permanent magnet motor based on the improved extended state observer, experimental verification was carried out under no-load and full-load conditions. Figure 3 The following are the motor experimental waveforms and their enlarged diagrams under no-load conditions, including the actual motor rotor position waveform, estimated rotor position waveform, estimated rotor position difference and q-axis current waveform. The experimental working condition is set as: no-load operation at a speed of 300rpm. Figure 3 It can be seen that the estimated rotor position can track the actual rotor position, and the estimated rotor position difference can be kept within 2.9°.

[0081] Figure 4 The following are the motor experimental waveforms and their enlarged diagrams under full load conditions, including the actual motor rotor position waveform, estimated rotor position waveform, estimated rotor position difference and q-axis current waveform. The experimental working condition is set to: full load operation at a speed of 300rpm. Figure 4 It can be seen that the estimated rotor position can track the actual rotor position, and the estimated rotor position difference can be kept within 9.6°.

[0082] In summary, the present invention uses an extended state observer based on a quasi-resonant observer to estimate the disturbance in real time on the basis of the traditional model reference adaptive positionless control based on stator current, and introduces super-helical sliding mode control to replace the traditional PI-based adaptive law to estimate the rotor position and speed of the motor in real time, thereby realizing the vector control system of the ship propulsion permanent magnet motor. The experimental results show that the present invention still has a high rotor position identification accuracy under heavy load conditions.

[0083] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A model reference adaptive position-free control method for a ship propulsion permanent magnet motor, characterized in that: The following steps are involved: Step 1: Introduce a quasi-resonant controller into the linear extended state observer to improve the estimation accuracy of periodic disturbances; Step 2: Based on the model reference adaptive method of stator current, a reference model and an adjustable model of permanent magnet motor position-free control are constructed, and the output signals of the two are used to design an adaptive law to estimate the motor rotor speed and position information, and the observed information is fed back to the adjustable model in real time to realize dynamic identification of the rotor position signal; Step 3: Introduce sliding mode control to replace the PI-based adaptive law, and use the super-helical sliding mode algorithm to further reduce the chattering of the sliding mode control and improve the robustness of speed identification; Step 4: Use the identified speed and position signals for closed-loop vector control of the motor and conduct experimental verification of the system.

2. The ship propulsion permanent magnet motor model reference adaptive position-free control method according to claim 1, characterized in that: The step 1 is specifically as follows: The quasi-resonant controller is introduced into the linear extended state observer and is designed as follows: where i d 、i q is the motor dq axis current, u d 、u q is the motor dq axis voltage, L d , L q is the motor dq axis inductance, R s is the stator resistance of the motor, f d 、f q is the disturbance signal, the estimated signal is represented by the symbol ^, e d 、e q is the estimated difference of dq axis current, p is the differential operator, β1 and β2 are the observation gain values ​​of the extended state observer, ω c and k r are the resonant bandwidth and resonant coefficient of the quasi-resonant observer, ω e is the motor rotor angular velocity, y dq 、x dq and g dq are different intermediate variables of the observer in the dq axis.

3. The ship propulsion permanent magnet motor model reference adaptive position-free control method according to claim 1, characterized in that: The step 2 is specifically as follows: The motor stator current equation can be expressed as: where i' d =i d +ψ f / L d ,i' q =i q ,u' d =u d +R s ψ f / L d ,u' q =u q , ψ f is the permanent magnet flux value of the motor. The adjustable model can be designed as:

4. The ship propulsion permanent magnet motor model reference adaptive position-free control method according to claim 1, characterized in that: The step three is specifically as follows: The sliding surface can be designed as: The identified speed can be expressed as: where k p , k i are the proportional and integral coefficients of the adaptive law, sigmoid ( ) is the S-type function, ω ref is the given motor angular velocity.

5. The ship propulsion permanent magnet motor model reference adaptive position-free control method according to claim 1, characterized in that: In step four, the position-free control algorithm is experimentally verified under different working conditions based on the permanent magnet motor prototype experimental platform.

Images