Permanent magnet synchronous motor extremely low speed robust position sensorless control method, device and system

Abstract

The invention discloses a permanent magnet synchronous motor extremely-low-speed robust position sensorless control method, device and system. The method comprises the following steps: performing ESO current-disturbance observation on dq-axis current values, voltage reference values and rotor position information at a k moment to obtain an observation current and a q-axis disturbance observation value at a k + 1 moment; the dq-axis current value, the observation current and the dq-axis current reference value at the k moment are observed through a rotor position observer, and the position and the rotating speed of a motor rotor at the k + 1 moment are obtained; adopting a feed-forward compensation method to obtain a q-axis voltage feed-forward value at the k + 1 moment according to the q-axis disturbance observation value at the k + 1 moment and the rotating speed of the motor at the k + 1 moment; and dynamically adjusting a q-axis voltage feed-forward value according to the position of the motor rotor at the k + 1 moment and the q-axis disturbance observation value, and realizing effective suppression of the torque ripple in the low-speed region. According to the method, the robustness and the anti-interference capability of a low-speed region are enhanced while the steady-state performance and the dynamic response of the system are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor control, and in particular relates to an extremely low-speed robust position sensorless control method, device and system for a permanent magnet synchronous motor. Background Art

[0002] In recent years, permanent magnet synchronous motor (PMSM) has become the preferred drive device in many industrial fields due to its high efficiency, high power density, simple structure and good speed regulation performance. With the advancement of control technology, especially the continuous development of vector control and direct torque control methods, PMSM has been widely used in precision manufacturing, aerospace, electric vehicles and other fields. According to the structure of the rotor permanent magnet, PMSM can be divided into surface mounted permanent magnet synchronous motor (SPMSM) and internal permanent magnet synchronous motor (IPMSM). Among them, IPMSM has received more and more attention due to its excellent weak magnetic properties and high power density.

[0003] In the traditional PMSM speed control system, it is usually necessary to install position sensors such as rotary encoders, Hall sensors or resolvers to detect the motor rotor position angle in real time, thereby achieving high-precision closed-loop control. However, the introduction of sensors not only increases the cost and complexity of the system, but also increases the failure rate of the system. Especially in harsh environments, the performance and reliability of the sensors are difficult to guarantee. In order to cope with these problems, PMSM position sensorless control technology has gradually become a research hotspot, especially sensorless control under extremely low speed operation is one of the technical difficulties.

[0004] In the extremely low speed region, due to the weak back EMF signal, the traditional sensorless control method based on back EMF observation cannot obtain accurate rotor position. In order to overcome this problem, researchers began to explore the use of motor salient pole characteristics or other observer designs to extract rotor position angle information. However, under extremely low speed operation, the PMSM control system faces multiple challenges, including the influence of cogging torque and friction, uncertainty of model parameters, etc. Especially when the motor is under large load fluctuations or there is interference in the system, the torque pulsation and current control accuracy are significantly reduced, affecting the overall performance.

[0005] To this end, many sensorless control strategies in the low-speed range have emerged in recent years. These methods can be roughly divided into two categories. One is the rotor position observation strategy based on high-frequency signal injection. This type of method is now relatively mature and commercially available, but the injection of high-frequency signals will cause additional torque pulsation and generate noise. In addition, non-salient motors often require larger injection voltages and higher injection frequencies when using high-frequency injection methods. These problems limit the use of such methods. The second is the rotor position observation strategy based on the model method, such as nonlinear flux observers, static compensation voltage observers, etc. The existing paper "Synchronization at startup and stable rotation reversal of sensorless nonsalient PMSM drives" records a rotor position observer based on static compensation voltage, but at extremely low speeds, the observer cannot achieve the ideal observation effect, and the article only gives the position observation method of the surface-mounted permanent magnet synchronous motor.

[0006] Therefore, designing a simpler, more effective and more versatile ultra-low-speed position sensorless control strategy has important research and application value for further expanding the application scenarios of PMSM, especially high-precision control under ultra-low speed conditions. Summary of the invention

[0007] The purpose of the present invention is to provide a method, device and system for extremely low-speed robust position sensorless control of a permanent magnet synchronous motor, which is used to solve the key problem of extremely low-speed position sensorless operation of a permanent magnet synchronous motor. The present invention feeds back the speed information extracted by the observer to the feedforward compensation link of the q-axis voltage and the ESO current-disturbance observer, further optimizing the response characteristics and anti-disturbance performance of the controller under low-speed conditions. At the same time, by combining the frequency selectivity of the quasi-proportional resonant filter (QPR) and the ESO lumped disturbance compensation function, the rotor position estimation error is effectively suppressed.

[0008] The present invention adopts the following technical solutions to solve the above technical problems:

[0009] In a first aspect, the present invention provides a method for extremely low-speed robust position sensorless control of a permanent magnet synchronous motor, the method comprising:

[0010] By performing ESO current-disturbance observation on the dq-axis current value, voltage reference value and rotor position information at time k, the observed current and q-axis disturbance observation value at time k+1 are obtained;

[0011] By observing the dq axis current value, the observed current and the dq axis current reference value at time k using a rotor position observer, the position and speed of the motor rotor at time k+1 are obtained;

[0012] The feedforward compensation method is used to obtain the q-axis voltage feedforward value at time k+1 based on the q-axis disturbance observation value at time k+1 and the motor speed at time k+1.

[0013] The q-axis voltage feedforward value is dynamically adjusted according to the position of the motor rotor at time k+1 and the q-axis disturbance observation value to achieve effective suppression of torque pulsation in the low-speed area.

[0014] In one embodiment, the calculation formula of the ESO current-disturbance observer is:

[0015]

[0016] Among them, R s is the stator resistance, L d is the d-axis inductance, L q is the q-axis inductance, β 1 , β 2 , is the observer gain, is the reference value of dq axis voltage, i d 、i q is the dq axis current value, To observe the current, is the q-axis perturbation observation value, ε d is the d-axis current observation error, ε q is the q-axis current observation error.

[0017] In one implementation, the rotor position observer is a rotor position observer with a current feedback compensator with quasi-proportional resonant filtering.

[0018] In one implementation, the current feedback compensator with proportional resonant filtering is expressed as:

[0019]

[0020] is the compensation current after filtering, QPR represents the QPR filter, is the observed current in the stationary coordinate system, Obtained by inverse park transformation; is the reference current in the stationary coordinate system, Inverse park transformation to obtain; i αβ is the sampling current, which is obtained by sampling the three-phase current i a ,i b ,i c Clark transformation is obtained, and the Clark transformation matrix is k is the compensation gain. The inverse park transformation matrix is The park transformation matrix is

[0021] In one implementation, the position and speed of the motor rotor at time k+1 are:

[0022]

[0023] Among them, T 2s / 2r is the Parker transformation matrix, QPR is the QPR type filter, is the observed current in the stationary coordinate system, Through the inverse Park transformation, the inverse Park transformation matrix is i dqc is the control current of the input position observer; is the reference current in the stationary coordinate system, Anti-Pike transformation is obtained; i αβ is the sampling current, k is the compensation gain, λ is the observer gain, Ψ m is the permanent magnet flux, i dc and i qc is the dq axis control current, is the reference value of dq axis voltage, and are the rotor position and speed values ​​obtained by the position observer.

[0024] In one implementation, the feedforward compensation method adopts a speed adaptive gain piecewise nonlinear hysteresis feedforward compensation form.

[0025] In one implementation, the speed adaptive gain piecewise nonlinear hysteresis feedforward compensation is in the form of:

[0026]

[0027] Among them, k low0 and k high0 is the initial gain, α low and α high is the gain adjustment factor, x h and x mid is the perturbation boundary, is the q-axis disturbance observation value, is the q-axis voltage feedforward value, is the gain control function, is the intermediate gain, Low gain factor, is the high gain coefficient, x is the formal parameter of the gain control function, and is used when used Replace x.

[0028] In one implementation, the gain is adjusted according to the rotation speed so that the system has different compensation strengths at different rotation speeds. The specific method is as follows:

[0029] When the rated speed is less than 1%, set the initial gain k low0 and k high0 Less than 0.1, gain adjustment coefficient α low Less than 0.1, benefit adjustment coefficient α high Less than 1;

[0030] When the rated speed is greater than 1%, set the initial gain k low0 and k high0 Less than 0.1, gain adjustment coefficient α low Less than 1, benefit adjustment coefficient α high Less than 10.

[0031] In a second aspect, the present invention provides an extremely low-speed robust position sensorless control device for a permanent magnet synchronous motor, the device comprising:

[0032] The ESO current-disturbance observer is used to perform ESO current-disturbance observation on the dq-axis current value, voltage reference value and rotor position information at time k to obtain the observed current and q-axis disturbance observation value at time k+1;

[0033] The rotor position observer is used to obtain the position and speed of the motor rotor at time k+1 by observing the dq axis current value, the observation current and the dq axis current reference value at time k using the rotor position observer;

[0034] The voltage feedforward module is used to perform feedforward compensation according to the q-axis disturbance observation value at time k+1 and the motor speed at time k+1, and dynamically adjust the q-axis voltage feedforward value according to the position of the motor rotor at time k+1 and the q-axis disturbance observation value, so as to effectively suppress the torque pulsation in the low-speed area.

[0035] In a third aspect, the present invention provides an extremely low-speed robust position sensorless control system for a permanent magnet synchronous motor, the system comprising: the extremely low-speed robust position sensorless control device for a permanent magnet synchronous motor described above.

[0036] The beneficial effects of the present invention are:

[0037] (1) The present invention effectively suppresses the DC interference in the stator current by using the ESO current-disturbance observer, and simultaneously observes and decouples the dq-axis back-EMF disturbance, providing strong support for the improved rotor position observer and the speed adaptive gain piecewise nonlinear hysteresis feedforward compensation method.

[0038] (2) The present invention improves the accuracy of speed and position estimation by using an improved position observer with a current feedback compensator with a quasi-proportional resonant filter, thereby ensuring the stable operation of the permanent magnet synchronous motor under extremely low speed conditions.

[0039] (3) The present invention improves the overall control performance by using the speed adaptive gain piecewise nonlinear hysteresis feedforward compensation method and the q-axis voltage feedforward without increasing the complexity of the dq-axis current loop. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an improper limitation of the present invention. Obviously, the accompanying drawings described below are only some embodiments. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0041] Figure 1 A flow chart of a method for extremely low-speed robust position sensorless control of a permanent magnet synchronous motor provided by an embodiment of the present invention;

[0042] Figure 2 This is a block diagram of the extremely low-speed robust position sensorless control system of the permanent magnet synchronous motor according to the present invention;

[0043] Figure 3 is a structural block diagram of an ESO current-disturbance observer provided in one embodiment;

[0044] Figure 4 It is a structural block diagram of an improved position observer with a current feedback compensator with quasi-proportional resonant filtering provided in one embodiment;

[0045] Figure 5 This is the experimental result diagram of the traditional static compensation voltage method, where Figure 5 (a) is the experimental result of the traditional method at 60% rated load. Figure 5 (b) is the experimental result of the traditional method under no-load;

[0046] Figure 6 6(a) is the result of the continuous forward and reverse rotation test of the control strategy proposed in the present invention at a speed of 10 rpm. Figure 6 (b) is the operating effect of the control strategy proposed in the present invention at a rotation speed of 2 rpm.

[0047] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0048] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, through which the features and advantages of the present invention will become more clear and distinct.

[0049] like Figure 1 As shown, an embodiment of the present invention shows a method for extremely low-speed robust position sensorless control of a permanent magnet synchronous motor, the method comprising the following steps:

[0050] Step S100: By performing ESO current-disturbance observation on the dq-axis current value, voltage reference value and rotor position information at time k, the observed current and q-axis disturbance observation value at time k+1 are obtained.

[0051] Furthermore, the calculation formula of the ESO current-disturbance observer is:

[0052]

[0053] Among them, R s is the stator resistance, L d is the d-axis inductance, L q is the q-axis inductance, β 1 , β 2 , is the observer gain, is the reference value of dq axis voltage, i d 、i q is the dq axis current value, To observe the current, is the q-axis perturbation observation value, ε d is the d-axis current observation error, ε q is the q-axis current observation error.

[0054] Step S200: derive the position and speed of the motor rotor at time k+1 by observing the dq-axis current value, the observed current and the dq-axis current reference value at time k using a rotor position observer.

[0055] In an optional embodiment, the rotor position observer is a rotor position observer with a current feedback compensator with quasi-proportional resonant filtering.

[0056] Furthermore, the current feedback compensator with proportional resonant filtering is expressed as:

[0057]

[0058] is the compensation current after filtering, QPR represents the QPR filter, is the observed current in the stationary coordinate system, Obtained by inverse park transformation; is the reference current in the stationary coordinate system, Inverse park transformation to obtain; i αβ is the sampling current, which is obtained by sampling the three-phase current i a ,i b ,i c Clark transformation is obtained, and the Clark transformation matrix is k is the compensation gain. The inverse park transformation matrix is The park transformation matrix is

[0059] The position and speed of the motor rotor at time k+1 are:

[0060]

[0061] Among them, T 2s / 2r is the Parker transformation matrix, QPR is the QPR type filter, is the observed current in the stationary coordinate system, Through the inverse Park transformation, the inverse Park transformation matrix is i dqc is the control current of the input position observer; is the reference current in the stationary coordinate system, Anti-Pike transformation is obtained; i αβ is the sampling current, k is the compensation gain, λ is the observer gain, Ψ m is the permanent magnet flux, i dc and i qc is the dq axis control current, is the reference value of dq axis voltage, and are the rotor position and speed values ​​obtained by the position observer.

[0062] Step S300: Adopting the feedforward compensation method, according to the q-axis disturbance observation value at time k+1 and the motor speed at time k+1, the q-axis voltage feedforward value at time k+1 is obtained.

[0063] In an optional embodiment, the feedforward compensation method adopts the form of speed adaptive gain piecewise nonlinear hysteresis feedforward compensation.

[0064] Furthermore, the speed adaptive gain piecewise nonlinear hysteresis feedforward compensation is in the form of:

[0065]

[0066] Among them, k low0 and k high0 is the initial gain, α low and α high is the gain adjustment factor, x h and xmid is the perturbation boundary, is the q-axis disturbance observation value, is the q-axis voltage feedforward value.

[0067] Furthermore, the gain is adjusted according to the speed so that the system has different compensation strengths at different speeds. A lower gain is set at low speed to avoid oscillation caused by excessive response, and the gain is increased at high speed to quickly suppress large disturbances. The specific method is:

[0068] When the rated speed is less than 1%, set the initial gain k low0 and k high0 Less than 0.1, gain adjustment coefficient α low Less than 0.1, benefit adjustment coefficient α high Less than 1; when the rated speed is greater than 1%, set the initial gain k low0 and k high0 Less than 0.1, gain adjustment coefficient α low Less than 1, benefit adjustment coefficient α high Less than 10.

[0069] Step S400: Dynamically adjust the q-axis voltage feedforward value according to the position of the motor rotor at time k+1 and the q-axis disturbance observation value to achieve effective suppression of torque pulsation in the low-speed area.

[0070] The present invention improves the system's steady-state performance and dynamic response while enhancing the robustness and anti-disturbance capability in the low-speed region by accurately observing the rotor position and speed, combining a quasi-proportional resonant controller (QPR) and an extended state observer (ESO). The speed information extracted by the observer is fed back to the feedforward compensation link of the q-axis voltage and the ESO current-disturbance observer, further optimizing the controller's response characteristics and anti-disturbance performance under low-speed conditions. At the same time, by combining the frequency selectivity of the quasi-proportional resonant controller (QPR) and the lumped disturbance compensation function of the ESO, effective suppression of the rotor position estimation error is achieved.

[0071] The following is an embodiment of a very low speed robust position sensorless control device for a permanent magnet synchronous motor of the present invention, which can be used to execute an embodiment of a very low speed robust position sensorless control method for a permanent magnet synchronous motor of the present invention. For details not disclosed in the embodiment of a very low speed robust position sensorless control device for a permanent magnet synchronous motor of the present invention, please refer to an embodiment of a very low speed robust position sensorless control method for a permanent magnet synchronous motor of the present invention.

[0072] Reference Figure 2 As shown, in one embodiment, a very low-speed robust position sensorless control device for a permanent magnet synchronous motor is provided, including an ESO current-disturbance observer, a rotor position observer and a voltage feedforward module.

[0073] The ESO current-disturbance observer is used to perform ESO current-disturbance observation on the dq-axis current value, voltage reference value and rotor position information at time k to obtain the observed current and q-axis disturbance observation value at time k+1;

[0074] The rotor position observer is used to obtain the position and speed of the motor rotor at time k+1 by observing the dq axis current value, the observation current and the dq axis current reference value at time k using the rotor position observer;

[0075] The voltage feedforward module is used to perform feedforward compensation according to the q-axis disturbance observation value at time k+1 and the motor speed at time k+1, and dynamically adjust the q-axis voltage feedforward value according to the position of the motor rotor at time k+1 and the q-axis disturbance observation value, so as to effectively suppress the torque pulsation in the low-speed area.

[0076] It should be noted that the various functional modules in the embodiments of the present invention may be integrated into one processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above integrated modules may be implemented in the form of hardware or in the form of software functional modules.

[0077] Specifically, the structure of the ESO current-disturbance observer is given by Figure 3 As shown, the input signal of the ESO current-disturbance observer is and i d 、i q Connected to the input signal of the inverse park transform and the output signal of the park transform. The current signal i after sampling and transformation d 、i q and the speed signal calculated by the observer After calculation, i d and i q Observed value and Lumped disturbance including q-axis back EMF

[0078] The dq axis current state equation of PMSM is:

[0079]

[0080] Considering the influence of parameter changes and disturbances, define ω ud and ω uq The lumped disturbance is described, and the dq axis current state equation of PMSM is:

[0081]

[0082] According to ESO, the input and disturbance of the system on the d-axis are ω ud The input and disturbance of the q-axis are formally the same as those of the d-axis.

[0083]

[0084] Based on the above, the ESO current-disturbance observer is designed as:

[0085]

[0086] Among them, R s is the stator resistance, L d is the d-axis inductance, L q is the q-axis inductance, β 1 , β 2 , is the observer gain. The input of the observer is the reference value of the dq axis voltage And the dq axis current value i obtained by current sensor collection and Park transformation d 、i q , the dq current observed after calculation output and q-axis lumped disturbance

[0087] Traditional static compensation voltage observers usually use current reference values ​​as the basis when calculating the dq-axis back EMF. However, this method has the following two limitations: First, the current closed loop relies on high-precision rotor position observation, and it is difficult to accurately reflect the dynamic response by directly using the reference current value, especially under extremely low speed or high load conditions, which may lead to closed-loop control failure; second, parameter errors and external disturbances have a great influence on the calculation accuracy of the open-loop back EMF, thereby introducing position estimation errors. In response to the above problems, the present invention designs a current feedback compensator (QPRCF) with proportional resonant filtering function based on the extended state observer (ESO), and inputs the compensated and filtered current signal into the observer to improve the position observation accuracy. The structure of the improved rotor observer is as follows: Figure 4 As shown. The dq axis voltage reference signal through the input and i d 、i q Observed value Sampling current i α 、i β , the observed speed signal is obtained by calculation and angle

[0088] Compensated control current Each is filtered by a QPR filter implemented in a closed loop to obtain a filtered estimated control current Then use it as feedback signal The control current error is obtained by subtracting and input into the QPR filter as the input signal, thus forming a complete closed-loop structure. The estimated current after filtering is transformed by park: It is used as the input current of the rotor position observer for position observation. As the resonant frequency, the QPR filter is introduced from the rotor position observer in the form of feedback to achieve its frequency adaptation.

[0089] The calculation formula of the rotor position observer is:

[0090]

[0091] Among them, T 2s / 2r is the Parker transform matrix, QPR is the QPR filter, is the observed current in the stationary coordinate system, Anti-Pike transformation is obtained; i dqc is the control current of the input position observer; is the reference current in the stationary coordinate system, Anti-Pike transformation is obtained; i αβ is the sampling current, k is the compensation gain. λ is the observer gain, Ψ m is the permanent magnet flux. The input is the dq axis control current i output by the current feedback compensator dc and i qc , the reference value of dq axis voltage u d 、u q , the rotor position obtained by the position observer and speed value

[0092] Based on the ESO current and disturbance observation, a speed adaptive gain piecewise nonlinear hysteresis voltage feedforward compensation method is proposed. Feedforwarding the q-axis voltage avoids introducing feedforward into the current loop and does not increase the complexity of the current loop. Observed speed signal The q-axis voltage feedforward value is obtained by calculation The feed-forward method of the q-axis voltage is:

[0093]

[0094] The piecewise gain function is designed as:

[0095]

[0096] in, is the disturbance boundary.

[0097] The adaptive function of gain and speed is defined as follows:

[0098]

[0099] Among them, k low0 and k high0 is the initial gain, α low and α high is the gain adjustment factor, x h and x mid is the perturbation boundary, is the q-axis disturbance observation value, is the q-axis voltage feedforward value, is the gain control function, is the intermediate gain, Low gain factor, is the high gain coefficient, x is the formal parameter of the gain control function, and is used when used Replace x.

[0100] Adjust the gain according to the speed so that the system has different compensation strengths at different speeds. Set a lower gain at low speeds to avoid oscillation caused by excessive response. Increase the gain at higher speeds to quickly suppress larger disturbances.

[0101] Continue to refer to Figure 2 As shown, in one embodiment, a permanent magnet synchronous motor ultra-low speed robust position sensorless control system is provided, the system at least includes: an ultra-low speed robust position sensorless control device for a permanent magnet synchronous motor, a speed loop PI controller, a current loop PI controller, a park converter, an anti-park converter, an SVPWM inverter, and a current sampling module.

[0102] For the description of the extremely low-speed robust position sensorless control device for a permanent magnet synchronous motor, refer to the description of the above embodiment and will not be repeated here.

[0103] In an embodiment of a permanent magnet synchronous motor ultra-low speed robust position sensorless control system of a basic FOC control method, the system also includes a speed loop PI controller, a current loop PI controller, a Park transform, two inverse Park transforms and a SVPWM inverter.

[0104] Specifically, the three-phase AC output terminal UVW of the SVPWM inverter is connected to the three-phase AC input terminal UVW of the permanent magnet synchronous motor. The current signal input terminal of the Park converter is connected to the output signal of the three-phase current sensor of the permanent magnet synchronous motor UVW. The angle signal of the Park converter and the anti-park converter The angle between the input and the rotor position observer The output terminal is connected to the rotor position observer. With the given value of speed After the difference is made, it is connected to the input of the speed loop PI controller. And the q-axis current reference value output by the speed loop The dq axis current output i of the Park converter d 、i q After the difference is made, it is connected to the input end of the dq axis current PI controller to convert the speed output of the rotor position observer Connected to the input of the dq axis current PI controller. The output of the dq axis current PI controller Connected to the input of the inverse park converter, the output of the dq axis current PI controller is connected to the output signal of the voltage feedforward module What you get after doing something wrong Connected to the input of the inverse park transform. The input signal of the ESO current-disturbance observer and i d 、i q Connected to the input signal of the inverse park transform and the output signal of the park transform. The input signal of the position observer and The input signal of the inverse park transform and the output signal of the ESO current-disturbance observer are connected to the input signal of the improved position observer. and i α 、i β Connected to the reference value of the dq axis current and the output signal of the Park transformation. The input signal of the voltage feedforward module and The output signal of the ESO current-disturbance observer and the output signal of the improved rotor position observer are connected. The reference voltage is inversely park-transformed and sent to the SVPWM link, and the generated control signal is sent to the inverter. The control voltage generated by the inverter is connected to the motor to control the motor.

[0105] The implementation method of the experimental platform of the present invention is: connect the PWM control signal output by the control board to the driver board, connect the current sampling signal output by the driver board to the control board, connect the DC voltage of the DC power supply to the DC side capacitor on the driver board, connect the UVW three-phase voltage output of the driver board to the motor, and connect the output of the motor encoder to the control board to observe the real speed and position of the motor. Connect the D / A output terminal on the control board and the output of the current sensor to the 4 channels of the oscilloscope. The motor parameters are shown in Table 1.

[0106] Table 1 Motor parameters and experimental conditions settings

[0107] parameter Numeric parameter Numeric Number of pole pairs (Np) 4 Stator resistance Rs(Ω) 1.65 Rated frequency(Hz) 100 D-axis inductance Ld(mH) 5.8 Rated speed (rpm) 1500 Q-axis inductance Lq(mH) 7.3 Rated current(A) 4 Permanent magnet flux (Wb) 0.32 Rated voltage(V) 380 Rated power (kW) 1.5

[0108] Said Figure 5The experimental results of the conventional static compensation voltage method are shown in Figure 1. The experimental condition is 10 rpm (0.67% rated speed). Figure 5 (a) is the experimental result of the traditional method at 60% rated load. Figure 5 (b) is the experimental result of the traditional method under no-load;

[0109] From the experimental results, it can be seen that with 60% rated load, the traditional control strategy cannot operate stably at a speed of 10 rpm; Figure 5 (b) shows the operating effect of the traditional method at 10 rpm under no-load. There is considerable jitter between the observed position and the actual position, and there is a lag in the observed position. The estimated speed effect is also unacceptable.

[0110] Said Figure 6 This is a comparison chart of the load test results of the control strategy proposed in the present invention. The load is set to 60% of the rated load. The experimental conditions are 10rpm (0.67% of the rated speed) and 2rpm (0.13% of the rated speed). Figure 6 (a) is the test result of the control strategy proposed in the present invention under the condition of 10 rpm continuous forward and reverse rotation. Figure 6 (b) is the operating effect of the control strategy proposed by the present invention at a speed of 2 rpm;

[0111] It can be seen from the experimental results that at a speed of 10rpm, the position observation error is basically kept within 0.5rad. The rotor position observation produces a phase difference in the process of switching from reverse to forward rotation, but it can be quickly recovered within 1 electrical angle cycle. The estimated value of the speed and the q-axis current fluctuate greatly. Thanks to the more accurate observation of the rotor position, the decoupling between the dq axis is more complete. From the dq axis current, it can be seen that the load disturbance of the q axis does not affect the d axis, which greatly improves the control performance of the entire system; at a speed of 2rpm, it can be seen that the speed and q axis current have considerable distortion. Even so, the proposed observer can still track the rotor position well. The error of the rotor position is also within 0.5rad. After the above test in the extremely low speed zone, the performance of the proposed observer is sufficient to ensure the observation effect above 2rpm.

[0112] The present invention effectively suppresses the influence of high-frequency interference on the dq-axis current observation by designing a current feedback compensator (QPR-CF) with quasi-proportional resonant filtering, and combines the extended state observer (ESO) to accurately estimate the back-EMF disturbance, thereby improving the dynamic performance of the system. At the same time, the speed adaptive gain piecewise nonlinear hysteresis compensation method (SAGA-HVF) is introduced to enable the system to adaptively adjust the feedforward gain in the extremely low speed area, effectively reduce the torque pulsation and improve the robustness of the system. The experimental results verify the superior performance of the proposed strategy in the extremely low speed area (as low as 2rpm) with load operation, showing strong adaptability to changes in motor parameters, and providing a feasible and efficient solution for high-precision position sensorless control in the low-speed area. Future work will further explore the performance of this method under complex loads and high dynamic environments and its potential for engineering applications.

[0113] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A very low speed robust position sensorless control method for a permanent magnet synchronous motor, characterized in that: The method comprises: By performing ESO current-disturbance observation on the dq-axis current value, voltage reference value and rotor position information at time k, the observed current and q-axis disturbance observation value at time k+1 are obtained; By observing the dq axis current value, the observed current and the dq axis current reference value at time k using a rotor position observer, the position and speed of the motor rotor at time k+1 are obtained; The feedforward compensation method is used to obtain the q-axis voltage feedforward value at time k+1 based on the q-axis disturbance observation value at time k+1 and the motor speed at time k+1. The q-axis voltage feedforward value is dynamically adjusted according to the position of the motor rotor at time k+1 and the q-axis disturbance observation value to achieve effective suppression of torque pulsation in the low-speed area.

2. The method for extremely low-speed robust position sensorless control of a permanent magnet synchronous motor according to claim 1, characterized in that: The expression of the ESO current-disturbance observation is: Among them, R s is the stator resistance, L d is the d-axis inductance, L q is the q-axis inductance, β1, β2, are the observer gains, is the reference value of dq axis voltage, i d 、i q is the dq axis current value, To observe the current, is the q-axis perturbation observation value, ε d is the d-axis current observation error, ε q is the q-axis current observation error.

3. The method for extremely low speed robust position sensorless control of a permanent magnet synchronous motor according to claim 1, characterized in that: The rotor position observation adopts a rotor position observer with a current feedback compensator having a quasi-proportional resonant filter.

4. The method for extremely low-speed robust position sensorless control of a permanent magnet synchronous motor according to claim 3, characterized in that: The current feedback compensator with proportional resonant filtering is expressed as: i dqc =(i dc ,i qc ) T is the compensation current after filtering, QPR represents the QPR filter, i αβ =(i α ,i β ) T is the observed current in the stationary coordinate system, Obtained by inverse park transformation; is the reference current in the stationary coordinate system, Inverse park transformation to obtain; i αβ is the sampling current, which is obtained by sampling the three-phase current i a ,i b ,i c Clark transformation is obtained, and the Clark transformation matrix is k is the compensation gain. The inverse park transformation matrix is The park transformation matrix is 5. The method for extremely low-speed robust position sensorless control of a permanent magnet synchronous motor according to claim 4, characterized in that: The position and speed of the motor rotor at time k+1 are: Among them, T 2s / 2r is the Parker transformation matrix, QPR is the QPR type filter, is the observed current in the stationary coordinate system, Through the inverse Park transformation, the inverse Park transformation matrix is i dqc is the control current of the input position observer; is the reference current in the stationary coordinate system, Anti-Pike transformation is obtained; i αβ is the sampling current, k is the compensation gain, λ is the observer gain, Ψ m is the permanent magnet flux, i dc and i qc is the dq axis control current, is the reference value of dq axis voltage, and are the rotor position and speed values ​​obtained by the position observer.

6. The method for extremely low speed robust position sensorless control of a permanent magnet synchronous motor according to claim 1 or 5, characterized in that: The feedforward compensation method adopts the form of speed adaptive gain piecewise nonlinear hysteresis feedforward compensation.

7. The method for extremely low speed robust position sensorless control of a permanent magnet synchronous motor according to claim 6, characterized in that: The speed adaptive gain piecewise nonlinear hysteresis feedforward compensation is in the form of: Among them, k low0 and k high0 is the initial gain, α low and α high is the gain adjustment factor, x h and x mid is the perturbation boundary, is the q-axis disturbance observation value, is the q-axis voltage feedforward value, is the gain control function, is the intermediate gain, Low gain factor, is the high gain coefficient, x is the formal parameter of the gain control function, and is used when used Replace x.

8. The method for extremely low speed robust position sensorless control of a permanent magnet synchronous motor according to claim 7, characterized in that: Adjust the gain according to the speed so that the system has different compensation strengths at different speeds. The specific method is: When the rated speed is less than 1%, set the initial gain k low0 and k high0 Less than 0.1, gain adjustment coefficient α low Less than 0.1, benefit adjustment coefficient α high Less than 1; When the rated speed is greater than 1%, set the initial gain k low0 and k high0 Less than 0.1, gain adjustment coefficient α low Less than 1, benefit adjustment coefficient α high Less than 10.

9. A very low speed robust position sensorless control device for a permanent magnet synchronous motor, characterized in that: The device comprises: The ESO current-disturbance observer is used to perform ESO current-disturbance observation on the dq-axis current value, voltage reference value and rotor position information at time k to obtain the observed current and q-axis disturbance observation value at time k+1; The rotor position observer is used to obtain the position and speed of the motor rotor at time k+1 by observing the dq axis current value, the observation current and the dq axis current reference value at time k using the rotor position observer; The voltage feedforward module is used to perform feedforward compensation according to the q-axis disturbance observation value at time k+1 and the motor speed at time k+1, and dynamically adjust the q-axis voltage feedforward value according to the position of the motor rotor at time k+1 and the q-axis disturbance observation value, so as to effectively suppress the torque pulsation in the low-speed area.

10. A very low speed robust position sensorless control system for a permanent magnet synchronous motor, characterized in that: The system includes: the extremely low-speed robust position sensorless control device for a permanent magnet synchronous motor as described in claim 9.

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