Permanent magnet synchronous motor position sensorless heavy load starting method

Abstract

The invention discloses a position-sensorless heavy-load starting method for a permanent magnet synchronous motor. The method comprises the following steps: establishing a discrete current model of the permanent magnet synchronous motor in a two-phase static coordinate system under the excitation of a high-frequency square wave signal; injecting the six-pulse voltage into the permanent magnet synchronous motor based on a three-phase static coordinate system to carry out rotor magnetic pole identification so as to correct the initial electrical angle of the rotor, and further obtaining a rotor position error signal in combination with a discrete current model; a rotor position error signal is processed through an improved phase-locked loop control system based on model reference self-adaption, and then the finally estimated rotating speed and electrical angle of the rotor are obtained; and then inputting the signal as a feedback signal into a magnetic field orientation control system to realize position-sensorless closed-loop starting control of the permanent magnet synchronous motor under a heavy load condition. By means of the method, the reliability of the starting process and the stability of a control system can be remarkably improved, and therefore reliable position-free closed-loop control under the low-speed large-load working condition and even within the full-speed domain range is achieved.

Description

Technical Field

[0001] The invention relates to a motor heavy-load starting method, relates to the technical field of motor control, and particularly to a position sensorless heavy-load starting method for a permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in industrial control, new energy vehicles, and other fields due to their high efficiency and power density. Traditional PMS motor control requires a position sensor to obtain rotor position information, which increases system cost and reduces reliability. Consequently, position-free control technology has become a research hotspot.

[0003] High-frequency injection is a commonly used control strategy for position-free control of permanent magnet synchronous motors in the zero-speed domain. This method estimates the rotor position by injecting a high-frequency excitation signal into the motor and detecting the current response. However, existing technologies have the following problems: 1) Traditional dual-pulse magnetic pole identification schemes based on an estimated coordinate system rely on initial position estimation results, which can lead to startup failures if the initial estimation is incorrect; 2) Existing phase-locked loop designs struggle to balance dynamic and steady-state performance, resulting in large fluctuations in the estimated speed. Summary of the Invention

[0004] To address the issues presented in the background art, this paper provides a sensorless, heavy-load starting method for a permanent magnet synchronous motor. By improving high-frequency signal injection and the phase-locked loop (PLL), this method significantly enhances the accuracy of rotor initial position identification and low-speed dynamic performance. It is widely applicable to new energy vehicles, industrial automation, and servo motor applications requiring high dynamic response.

[0005] The technical solution adopted in the present invention is:

[0006] The present invention provides a position sensorless heavy-load starting control method for a permanent magnet synchronous motor, comprising:

[0007] Step 1) Establish a discrete current model of a permanent magnet synchronous motor in a two-phase stationary coordinate system under high-frequency square wave signal excitation.

[0008] Step 2) Inject six pulse voltages into the permanent magnet synchronous motor based on the three-phase stationary coordinate system, and then perform rotor magnetic pole identification to correct the initial position of the permanent magnet synchronous motor rotor. Electrical angle ,According to the corrected initial electrical angle of the rotor and the discretized current model, the rotor position error signal is obtained using the heterodyne method.

[0009] Step 3) The rotor position error signal is processed by an improved model reference adaptive phase-locked loop (MRA-PLL) control system to obtain the final estimated rotor speed and electrical angle.

[0010] Step 4) The final estimated rotor speed and electrical angle are used as feedback signals and input into the field-oriented control (FOC) system of the permanent magnet synchronous motor to implement position sensorless closed-loop starting control of the permanent magnet synchronous motor under heavy load conditions.

[0011] In the step 1), the discretized current model of the permanent magnet synchronous motor in the two-phase stationary coordinate system is as follows:

[0012]

[0013] Among them, Δi αh and Δi βh are the high-frequency current response difference signals of the permanent magnet synchronous motor on the α-axis and β-axis respectively; U inj and T h are the voltage amplitude and period of the high-frequency square wave signal respectively; L d is the d-axis inductance parameter of the permanent magnet synchronous motor; θ e is the actual electrical angle of the rotor of the permanent magnet synchronous motor.

[0014] The step 2) is as follows:

[0015] Step 2.1) In the three-phase stationary coordinate system, the space of the permanent magnet synchronous motor is divided into six sectors. The middle position of each sector corresponds to the positive and negative directions of the three phases. Then, the same pulse voltage is injected simultaneously in the positive and negative directions of the three phases.

[0016] Step 2.2) Obtain the peak values of the stator current responses generated by the six sectors. Based on the inherent magnetic reluctance salient pole characteristics of the permanent magnet synchronous motor, identify the sector where the stator current response with the largest peak value is located as the initial sector where the rotor N pole of the permanent magnet synchronous motor is located.

[0017] Step 2.3) Obtain the estimated electrical angle of the rotor of the permanent magnet synchronous motor based on the high-frequency current response difference signal of the permanent magnet synchronous motor in the two-phase stationary coordinate system, and then determine the estimated initial position of the rotor. If the estimated initial position of the rotor of the permanent magnet synchronous motor is within the initial sector, the identification is completed, and the estimated electrical angle of the rotor is used as the initial electrical angle of the rotor; if the estimated initial position of the rotor is within the diagonal sector that differs from the initial sector by 180°, the estimated electrical angle of the rotor is added by 180° for correction, so as to identify and obtain the initial electrical angle of the rotor; if the estimated initial position is within two sectors adjacent to the initial sector, the estimated initial position of the rotor is obtained again based on the high-frequency current response difference signal of the permanent magnet synchronous motor in the two-phase stationary coordinate system, and repeat step 2.3) until the corrected initial electrical angle of the rotor is identified, thereby obtaining the rotor position error signal.

[0018] In step 2), the rotor position error signal ε is as follows:

[0019]

[0020] Where K is the error coefficient; is the initial electrical angle of the rotor after correction; U inj and T h are the voltage amplitude and period of the high-frequency square wave signal respectively; L d and L q are the d-axis and q-axis inductance parameters of the permanent magnet synchronous motor respectively.

[0021] In the step 3), an integral model based on the improved transfer function is constructed as a reference model in the model reference adaptive phase-locked loop MRA-PLL control system, thereby constructing an improved model reference adaptive phase-locked loop MRA-PLL control system, and improving the transfer function G e (s) are as follows:

[0022] G e (s) = K r (G c (s)-G h (s))

[0023] Where s is the complex frequency variable in the Laplace transform in the field of control system theory and signal processing; K r is the adjustable proportional feedforward control coefficient; G c () and G h () are the initial transfer function of the reference model and the phase-locked loop control transfer function respectively.

[0024] The adjustable proportional feedforward control coefficient K r The details are as follows:

[0025]

[0026] Among them, K rmax is the proportional feedforward control coefficient K r t1 is the characteristic moment at which the permanent magnet synchronous motor ends its speed regulation phase after starting, and t0 is the characteristic moment at which the permanent magnet synchronous motor ends its speed increase phase after starting.

[0027] The control transfer function is as follows:

[0028]

[0029] Among them, ζ and ω c are the design damping coefficient and design cutoff frequency of the phase-locked loop respectively.

[0030] The phase-locked loop control transfer function is as follows:

[0031]

[0032] Among them, K p and K i They are respectively the proportional gain and integral gain of the proportional-integral PI (Proportional-Integral) controller in the improved model reference adaptive phase-locked loop MRA-PLL control system.

[0033] The method of the present invention first analyzes the mathematical model of a permanent magnet synchronous motor (PMSM) to establish the relationship between the motor's high-frequency current response and rotor position under high-frequency signal excitation, providing a theoretical basis for sensorless control. Based on this, a six-pulse voltage injection magnetic pole identification scheme based on a three-phase stationary coordinate system is used to accurately identify the initial sector position of the motor's rotor north pole. Subsequently, a preliminary rotor electrical angle estimate is calibrated based on this identification result. A position error signal is calculated based on the position estimation principle in a two-phase stationary coordinate system, combining the mathematical relationship model with the high-frequency current response difference signal acquired in real time and processed without filter signal separation. Finally, this position error signal is input into a module using an improved MRA-PLL control and an improved progressive feedforward control rate for processing, thereby obtaining the final estimated motor rotor speed and estimated electrical angle. This precisely estimated speed and angle information is then input into the motor's field-oriented control (FOC) system, enabling sensorless closed-loop starting of the PMSM under heavy load conditions.

[0034] The beneficial effects of the present invention are:

[0035] The method of the present invention can significantly improve starting reliability and control stability, and realize reliable position-free closed-loop control under low speed, high load and full speed range. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a flowchart of an embodiment of the present invention;

[0037] Figure 2 Schematic diagram of magnetic pole identification based on a stationary coordinate system using six pulse injections according to an embodiment of the present invention;

[0038] Figure 3 This is a block diagram of an MRA-PLL control according to an embodiment of the present invention;

[0039] Figure 4 2 is a structural block diagram of a motor control system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the specific embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention.

[0041] like Figure 1 As shown, the position sensorless heavy-load starting control method of the permanent magnet synchronous motor of the present invention is specifically as follows:

[0042] Step 1) Establish a discretized current model of the permanent magnet synchronous motor in a two-phase stationary coordinate system under the excitation of a high-frequency square wave signal, where the frequency of the high-frequency square wave signal is 5kHz; based on the dq synchronous rotating coordinate coefficient mathematical model of the permanent magnet synchronous motor, derive and establish a mathematical relationship model between the high-frequency current response generated by the permanent magnet synchronous motor in a two-phase stationary coordinate system under the excitation of the high-frequency square wave signal and the actual electrical angle of the rotor, providing a theoretical basis for estimating the rotor position by detecting the high-frequency current response of the motor.

[0043] First, a mathematical model of the permanent magnet synchronous motor is constructed based on the dq coordinate system. The high-frequency current response model of the two-phase stationary shaft system under high-frequency signal excitation is derived as follows:

[0044]

[0045] Among them, i αh and i βh are the high-frequency current responses in the two-phase stationary coordinate system; T -1 is the inverse Park transform; θ e and are the actual electrical angle and estimated electrical angle of the rotor of the permanent magnet synchronous motor respectively; It represents the high-frequency stator current in the dq axis system. The subscript h indicates that the corresponding signal is a high-frequency quantity.

[0046] By splitting and discretizing the high-frequency current response, the discretized current model of the permanent magnet synchronous motor in the two-phase stationary coordinate system can be obtained as follows:

[0047]

[0048] Among them, Δi αh and Δi βh are the high-frequency current response difference signals of the permanent magnet synchronous motor on the α-axis and β-axis respectively; i α (k) and i α (k-1) are the α-axis currents at sampling time k and k-1 respectively, i β (k) and i β (k-1) are the β-axis currents at sampling time k and k-1 respectively; U inj and T h are the voltage amplitude and period of the high-frequency square wave signal respectively; L d is the d-axis inductance parameter of the permanent magnet synchronous motor.

[0049] Step 2) Inject six pulse voltages into the permanent magnet synchronous motor based on the three-phase stationary coordinate system, and then perform rotor magnetic pole identification to correct the initial position of the permanent magnet synchronous motor rotor. Electrical angle , according to the corrected initial electrical angle of the rotor and the discretized current model, the rotor position error signal is obtained using the heterodyne method, as follows:

[0050] Step 2.1) Figure 2 As shown, first, in the three-phase stationary coordinate system, the space of the permanent magnet synchronous motor is divided into 6 sectors: -60°~60°, 0°~120°, 60°~180°, 120°~240°, 180°~300°, and 240°~360°; the middle position of each sector corresponds to the positive and negative directions of the three phases, defined as: A+, A-, B+, B-, C+, and C-; then the same pulse voltage is injected simultaneously in the positive and negative directions of the three phases, the maximum amplitude of the injected voltage is 0.06 times the bus voltage, and the injected pulse voltage has a duty cycle of 6%.

[0051] Step 2.2) Obtain the peak values of the stator current responses generated by the six sectors. Based on the inherent magnetic reluctance salient pole characteristics of the permanent magnet synchronous motor, identify the sector where the stator current response with the largest peak value is located as the initial sector where the rotor N pole of the permanent magnet synchronous motor is located.

[0052] Step 2.3) Obtain the estimated electrical angle of the rotor of the permanent magnet synchronous motor based on the high-frequency current response difference signal of the permanent magnet synchronous motor in the two-phase stationary coordinate system, and then determine the estimated initial position of the rotor. If the estimated initial position of the rotor of the permanent magnet synchronous motor is within the initial sector, the identification is completed, and the estimated electrical angle of the rotor is used as the initial electrical angle of the rotor; if the estimated initial position of the rotor is within the diagonal sector that differs from the initial sector by 180°, the estimated electrical angle of the rotor is added by 180° for correction, so as to identify and obtain the initial electrical angle of the rotor; if the estimated initial position is within two sectors adjacent to the initial sector, the estimated initial position of the rotor is obtained again based on the high-frequency current response difference signal of the permanent magnet synchronous motor in the two-phase stationary coordinate system, and repeat step 2.3) until the corrected initial electrical angle of the rotor is identified, thereby obtaining the rotor position error signal.

[0053] During the identification process, the filter-free signal separation principle is used to extract the high-frequency current response containing the rotor position information as follows:

[0054] Since the frequency of high-frequency signal changes is much higher than the fundamental frequency signal of the current loop, it is assumed that the fundamental frequency current signal remains unchanged between the two sampling points before and after a sampling cycle. Based on this assumption, the fundamental current in the αβ coordinate system can be expressed as:

[0055]

[0056] Among them, f k and s k are the fundamental component and stator quantity at the kth sampling moment respectively.

[0057] The high-frequency response current in the αβ coordinate system can be expressed as:

[0058]

[0059] Among them, h k is the high-frequency component at the kth sampling moment.

[0060] The extraction method takes into account the sign of the injected voltage and can obtain its differential value while extracting the high-frequency current, as follows:

[0061]

[0062] Among them, sign() means extracting the polarity of the signal. It represents the estimated d-axis injection voltage at the current sampling time k.

[0063] Then, a preliminary position error signal is calculated based on the mathematical relationship and the real-time high-frequency current response difference signal processed by filter-free signal separation.

[0064] First, the high-frequency current response under the stationary shaft system is expressed as follows:

[0065]

[0066] Among them, i αh and i βh They are the high-frequency current responses in the two-phase stationary coordinate system. Further expansion and decomposition using the sum-difference-product formula yields:

[0067]

[0068] Wherein, L0 is the average inductance of the permanent magnet synchronous motor.

[0069] Considering that after the estimated position information converges, the rotor position error is close to 0, that is, Therefore, the above formula can be simplified to:

[0070]

[0071] Discretize the above formula and we can get:

[0072]

[0073] It can be seen that in the differential signal of the high-frequency current response in the stationary coordinate system αβ, there is an orthogonal signal related to the actual rotor position. On the oscilloscope, it can be seen that the high-frequency current response is the high-frequency envelope of the fundamental frequency sinusoidal signal. Therefore, by substituting the sign function and using the heterodyne method, the error signal used to estimate the rotor position information can be constructed as follows:

[0074]

[0075] Where K is the error coefficient; is the initial electrical angle of the rotor after correction; U inj and T h are the voltage amplitude and period of the high-frequency square wave signal respectively; L d and L q are the d-axis and q-axis inductance parameters of the permanent magnet synchronous motor respectively.

[0076] Step 3) The rotor position error signal is processed by the improved model reference adaptive phase-locked loop (MRA-PLL) control system to obtain the final estimated rotor speed and electrical angle, and an integral model based on the improved transfer function is constructed as a reference model in the model reference adaptive phase-locked loop (MRA-PLL) control system, thereby constructing an improved model reference adaptive phase-locked loop (MRA-PLL) control system; during the estimation process, the phase-locked loop performance is optimized based on the model reference adaptive control principle, and the speed and angle information are dynamically estimated.

[0077] like Figure 3 As shown in the figure, the MRA-PLL control principle is improved. By taking a specific integral model as the reference model of the control system, the steady-state fluctuation of the estimated speed is simulated and obtained. The estimated speed output of the PI controller is corrected by proportional feedforward control, so that the fluctuation error between the two approaches 0, and finally the steady-state fluctuation of the estimated speed is reduced, so that the steady-state effect of the estimation system is effectively improved.

[0078] The controller model in the system is expressed, and its transfer function is as follows:

[0079]

[0080] Among them, ζ is the system damping coefficient, which is generally set to 0.707; ω c is the system cutoff frequency.

[0081] Based on the transfer function of the above formula, the present invention proposes to simulate the steady-state fluctuation of its output with a specific reference model. The transfer function of the reference model is as follows:

[0082]

[0083] The parameters are all parameters in the controller transfer function, which can be expressed as the known parameter part under the steady-state speed condition.

[0084] The final transfer function is obtained by subtracting the two equations and multiplying them by the proportional coefficient:

[0085]

[0086] Among them, K r is the proportional control coefficient, which is used to adjust the amplitude of the error signal. This signal is fed forward to the estimated speed output by the controller in real time to correct the steady-state fluctuations of the estimated speed, thereby improving the steady-state effect of the estimated speed.

[0087] The final improved transfer function G e (s) are as follows:

[0088] G e (s) = K r (G c (s)-G h (s))

[0089]

[0090] Where s is the complex frequency variable in the Laplace transform in the field of control system theory and signal processing; K r is the adjustable proportional feedforward control coefficient; G c () and Gh () are the initial transfer function of the reference model and the phase-locked loop control transfer function respectively; ζ and ω c are the design damping coefficient and design cutoff frequency of the phase-locked loop respectively; K p and K i They are respectively the proportional gain and integral gain of the proportional-integral PI controller in the improved model reference adaptive phase-locked loop MRA-PLL control system.

[0091] Improved transfer function G e (s) is obtained by the transfer function G c The output of (s) (actual estimated speed related quantity) and the transfer function G h (s) output (ideal fluctuation characteristic related quantity) is subtracted and multiplied by the adjustable proportional feedforward control coefficient K r And get.

[0092] According to the principle of model reference adaptive control, the output error between the controller and the reference model needs to be fed back to the controller to adjust its internal parameters. This method uses feedforward control to directly correct the estimated speed output by the phase-locked loop (PLL), thereby reducing the steady-state fluctuations in the estimated speed.

[0093] On the basis of improving the phase-locked loop principle, a time-based progressive feedforward control method is proposed to adjust the control parameter K. r , to ensure the stability of the improved partial feedforward control, its function is as follows:

[0094]

[0095] Among them, K rmax is the proportional feedforward control coefficient K r The preset maximum value; t1 is the characteristic moment when the permanent magnet synchronous motor ends the speed regulation phase after starting, and t0 is the characteristic moment when the permanent magnet synchronous motor ends the speed rise phase after starting; the time interval t≤t0 represents the rise time of the control system; the time interval t0≤t≤t1 represents the adjustment time of the control system; t≥t1 is the steady-state process.

[0096] Two key time thresholds t0 and t1 are pre-set. When the operating time of the control system is t≤t0 (i.e. the motor is in the initial speed ramp-up phase), the proportional feedforward control coefficient K is forced to be set during the ramp-up time. r= 0, the purpose of which is to ensure that the phase of the phase-locked loop can be quickly and accurately locked in the initial startup stage, avoiding any adverse interference of the feedforward correction signal on this key process; when the running time of the control system satisfies t0 < t ≤ t1 (i.e., the motor is in the speed regulation transition stage), that is, within the regulation time, since the phase locking is basically completed, the proportional feedforward control coefficient K r will start from 0 and gradually and linearly increase according to the position of the current running time t relative to t0 and t1 until it reaches the preset maximum value K rmax , which not only ensures that the system adjustment within the regulation time is not affected but also avoids ensuring the gradualness of the feedforward control, effectively avoiding system chattering; after it is judged that the estimated speed enters the steady state, a proportional feedforward control with a constant parameter K rmax is ensured.

[0097] By gradually introducing the feedforward correction amount in the above manner, it aims to ensure the smooth transition of the motor control system during the speed regulation process and effectively avoid the system chattering phenomenon that may be caused by the sudden change of the correction signal; when the running time t of the control system > t1 (i.e., after the system judges that the estimated speed has entered the relatively stable running stage), the proportional feedforward control coefficient K r will remain at the constant maximum value K r max to perform continuous and stable steady-state fluctuation feedforward correction on the estimated speed.

[0098] Step 4) Take the finally accurately estimated rotor speed and electrical angle as feedback signals and input them into the field-oriented control FOC system of the permanent magnet synchronous motor to achieve sensorless closed-loop startup control of the permanent magnet synchronous motor under heavy load conditions.

[0099] The reference model of the improved model reference adaptive based phase-locked loop MRA-PLL control system is used to simulate and output the steady-state fluctuation characteristics that the estimated speed should have under ideal conditions; when performing the rotor position error signal for feedforward correction, the rotor position error signal is input, and the actual estimated speed output by the standard PI controller inside the phase-locked loop is compared with the ideal steady-state fluctuation signal output by the reference model in real time, so as to obtain the error signal e between the two; further adopting a feedforward control strategy, after adjusting this error signal e through an adjustable proportional gain, it is feedforward superimposed on the estimated speed output by the standard PI controller of the phase-locked loop for direct correction, the purpose of which is to make the steady-state fluctuation characteristics of the actually estimated speed after correction actively approach the ideal fluctuation characteristics defined by the reference model, thereby effectively reducing the overall fluctuation amplitude of the estimated speed during steady-state operation and significantly improving the steady-state performance of the motor control system; thus inside the phase-locked loop, the rotor position error signal ε is converted into an estimated speed through the corrected PI controller and then the estimated speed is passed through an integral link Converted into estimated electrical angle θ.

[0100] like Figure 4 Figure 1 is a schematic diagram of the system structure of a position sensorless heavy-load starting method for a permanent magnet synchronous motor provided by an embodiment of the present invention. As shown in the figure, the position sensorless control system of the permanent magnet synchronous motor includes: a permanent magnet synchronous motor, a current sensor, a position estimation module, a current controller, a space vector pulse width modulator, and an inverter. The control process is as follows:

[0101] 1. Control instructions and signal injection:

[0102] The system receives the external speed command The command and the estimated speed of the feedback After comparison, the difference is passed through the PI controller and the MTPA (Maximum Torque Per Ampere) module to generate the current instructions for the d-axis and q-axis. and At the same time, in order to perform position sensorless control, the system injects a high-frequency square wave voltage signal into the d-axis.

[0103] 2. Current control and pulse width modulation PWM (Pulse Width Modulation):

[0104] Generated and The feedback d-axis current i d and q-axis current i q The difference is compared and passed through the respective PI controllers to generate voltage commands for the d-axis and q-axis. and These voltage commands are transformed by inverse Park (dq to αβ) to obtain the voltage commands in the two-phase stationary coordinate system. and Then, and Input the space vector pulse width modulation (SVPWM) module to generate a three-phase pulse width modulation (PWM) switching signal S a 、S b and S c , drives the inverter, and ultimately acts on the permanent magnet synchronous motor PMSM (Permanent Magnet Synchronous Motor).

[0105] 3. Current sampling and signal separation:

[0106] The three-phase actual current i of the motor is collected by the current sensor a 、ib and i c These three-phase currents are transformed by Clarke (abc to αβ) to obtain the current signal i in the two-phase stationary coordinate system. α and i β Then, the filterless carrier signal separation module is used to separate the signal from i α and i β Separate the fundamental current signal i αf and i βf (for current loop feedback) and high-frequency current response signal i αh and i βh (Used for position and speed estimation). The separated fundamental current i αf and i βf After Park transformation, the feedback d-axis current i is obtained d and q-axis current i q .

[0107] 4. Position and velocity estimation and optimization:

[0108] The separated high-frequency current response signal i αh and i βh The error signal is input to the original error signal calculation module and combined with the current estimated angle θ (from the integral output of the phase-locked loop) to calculate the preliminary position error signal ε. The error signal ε is first input to a standard PI phase-locked loop PI-PLL, whose output is the preliminary estimated speed. And the estimated electrical angle θ obtained by integration. In order to further optimize the performance, The error signal ε is simultaneously input to the MRA-PLL speed estimation module, which contains a reference model and a control law. Make corrections and output the final, more accurate estimated speed this As the feedback signal of the outermost speed loop.

[0109] 5. Closed-loop feedback:

[0110] Final estimated speed The estimated electrical angle θ obtained by integrating the phase-locked loop is used for closed-loop feedback of the control system, including feedback of the speed loop and angle information required for coordinate transformation, thereby achieving precise control of the motor.

[0111] The method of the present invention first analyzes the mathematical model of a permanent magnet synchronous motor (PMSM) to establish the relationship between the motor's high-frequency current response and rotor position under high-frequency signal excitation, providing a theoretical basis for sensorless control. Based on this, a six-pulse voltage injection magnetic pole identification scheme based on a three-phase stationary coordinate system is used to accurately identify the initial sector position of the motor's rotor north pole. Subsequently, a preliminary rotor electrical angle estimate is calibrated based on this identification result. Combining the aforementioned mathematical relationship model with the high-frequency current response difference signal acquired in real time and processed without filter signal separation, a position error signal is calculated based on the position estimation principle in a two-phase stationary coordinate system. Finally, this position error signal is input into a module that utilizes an improved MRA-PLL control principle and an improved progressive feedforward control rate for processing, thereby obtaining the final estimated motor rotor speed and estimated electrical angle. This precisely estimated speed and angle information is then input into the motor's field-oriented control (FOC) system, enabling sensorless closed-loop starting of the PMSM under heavy load conditions. Compared with the existing technology, the permanent magnet synchronous motor position sensorless heavy-load starting control method proposed in the present invention can significantly improve the reliability of the starting process and the stability of the control system, thereby realizing reliable position-free closed-loop control under low-speed and high-load conditions and even in the full speed range.

[0112] The above are only specific embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for controlling the starting of a permanent magnet synchronous motor without a position sensor and under heavy load, characterized in that: include: Step 1) establishing a discretized current model of a permanent magnet synchronous motor in a two-phase stationary coordinate system under high-frequency square wave signal excitation; Step 2) Inject six pulse voltages into the permanent magnet synchronous motor based on the three-phase stationary coordinate system, and then perform rotor magnetic pole identification to correct the initial position of the permanent magnet synchronous motor rotor. Electrical angle , according to the corrected initial electrical angle of the rotor and the discretized current model, the rotor position error signal is obtained using the heterodyne method; Step 3) Processing the rotor position error signal by an improved model reference adaptive phase-locked loop (MRA-PLL) control system to obtain the final estimated rotor speed and electrical angle; Step 4) The final estimated rotor speed and electrical angle are used as feedback signals and input into the field oriented control (FOC) system of the permanent magnet synchronous motor to implement position sensorless closed-loop starting control of the permanent magnet synchronous motor under heavy load conditions.

2. The method for controlling a permanent magnet synchronous motor starting under heavy load and without a position sensor according to claim 1, wherein: In the step 1), the discretized current model of the permanent magnet synchronous motor in the two-phase stationary coordinate system is as follows: Among them, Δi αh and Δi βh are the high-frequency current response difference signals of the permanent magnet synchronous motor on the α-axis and β-axis respectively; U inj and T h are the voltage amplitude and period of the high-frequency square wave signal respectively; L d is the d-axis inductance parameter of the permanent magnet synchronous motor; θ e is the actual electrical angle of the rotor of the permanent magnet synchronous motor.

3. The method for controlling a permanent magnet synchronous motor starting under heavy load and without a position sensor according to claim 1, wherein: The step 2) is as follows: Step 2.1) In a three-phase stationary coordinate system, divide the space of the permanent magnet synchronous motor into six sectors, with the center of each sector corresponding to the positive and negative directions of the three phases. Then, inject the same pulse voltage simultaneously in the positive and negative directions of the three phases. Step 2.2) obtaining the peak values of the stator current responses generated by the six sectors, and identifying the sector where the stator current response with the largest peak value is located as the initial sector where the rotor N pole of the permanent magnet synchronous motor is located; Step 2.3) Obtain an estimated electrical angle of the permanent magnet synchronous motor's rotor based on a high-frequency current response difference signal of the permanent magnet synchronous motor in a two-phase stationary coordinate system, and then determine an estimated initial position of the rotor. If the estimated initial position of the permanent magnet synchronous motor's rotor is within the initial sector, identification is complete, and the estimated electrical angle of the rotor is used as the initial electrical angle of the rotor. If the estimated initial position of the rotor is located in a diagonal sector that differs from the initial sector by 180°, the estimated electrical angle of the rotor is added with 180° for correction, thereby identifying and obtaining the initial electrical angle of the rotor; if the estimated initial position is located in two sectors adjacent to the initial sector, the estimated initial position of the rotor is obtained again based on the high-frequency current response difference signal of the permanent magnet synchronous motor in the two-phase stationary coordinate system, and step 2.3) is repeated until the corrected initial electrical angle of the rotor is identified, thereby obtaining the rotor position error signal.

4. The method for controlling a permanent magnet synchronous motor starting under heavy load and without a position sensor according to claim 3, wherein: In step 2), the rotor position error signal ε is as follows: Where K is the error coefficient; is the initial electrical angle of the rotor after correction; U inj and T h are the voltage amplitude and period of the high-frequency square wave signal respectively; L d and L q are the d-axis and q-axis inductance parameters of the permanent magnet synchronous motor respectively.

5. The method for controlling a permanent magnet synchronous motor starting under heavy load and without a position sensor according to claim 1, wherein: In the step 3), an integral model based on the improved transfer function is constructed as a reference model in the model reference adaptive phase-locked loop MRA-PLL control system, thereby constructing an improved model reference adaptive phase-locked loop MRA-PLL control system, and improving the transfer function G e (s) are as follows: G e (s)=K r (G c (s)-G h (s)) Where s is the complex frequency variable; K r is the proportional feedforward control coefficient; G c () and G h () are the initial transfer function of the reference model and the phase-locked loop control transfer function respectively.

6. The method for controlling a permanent magnet synchronous motor starting under heavy load and without a position sensor according to claim 5, characterized in that: The proportional feedforward control coefficient K r The details are as follows: Among them, K rmax is the proportional feedforward control coefficient K r t1 is the characteristic moment at which the permanent magnet synchronous motor ends its speed regulation phase after starting, and t0 is the characteristic moment at which the permanent magnet synchronous motor ends its speed increase phase after starting.

7. The method for controlling a permanent magnet synchronous motor starting under heavy load and without a position sensor according to claim 5, wherein: The control transfer function is as follows: Among them, ζ and ω c are the design damping coefficient and design cutoff frequency of the phase-locked loop respectively.

8. The position sensorless heavy-load starting control method for a permanent magnet synchronous motor according to claim 5, characterized in that: The phase-locked loop control transfer function is as follows: Among them, K p and K i They are respectively the proportional gain and integral gain of the proportional-integral PI controller in the improved model reference adaptive phase-locked loop MRA-PLL control system.

Images