A position sensorless wind start method

Abstract

The application discloses a position-sensor-free headwind and tailwind starting method applied to a permanent magnet synchronous motor, and comprises the following steps: S1, continuously applying a first type of vector pulse to the permanent magnet synchronous motor to determine a current vector position and an initial rotating speed observation value; S2, determining an initial operation state of the permanent magnet synchronous motor, and processing the permanent magnet synchronous motor based on the initial operation state: when the rotor rotates in a tailwind direction, starting the permanent magnet synchronous motor after executing braking on the rotor; S3, when the rotor is in a first rotating speed state, waiting for the permanent magnet synchronous motor to naturally stop rotating under load and then starting the permanent magnet synchronous motor; and S4, when the rotor is in a second rotating speed state, determining a calibration initial position and a calibration initial rotating speed of the permanent magnet synchronous motor, and starting the permanent magnet synchronous motor according to the calibration initial position and the calibration initial rotating speed. The permanent magnet synchronous motor is subjected to different controls at headwind and tailwind positions, and the operation stability of the permanent magnet synchronous motor is improved.

Description

Technical Field

[0001] This invention relates to the field of motor drive control, and in particular to a sensorless method for starting with or against the wind. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs), with their advantages of high power density, high operating efficiency, and fast dynamic response, have been widely adopted in air conditioning fans, refrigeration compressors, industrial drives, and new energy vehicles. To reduce hardware costs, decrease system installation size, and improve long-term operational reliability, an increasing number of PMSM drive solutions employ sensorless control methods, relying solely on collectable voltage and current signals to estimate rotor position and speed in real time. In practical applications such as fans and high-inertia loads, after a motor stops, it is often kept rotating due to external wind force, load inertia, or residual system energy. When the control system restarts, the motor may be rotating with the wind in the same direction as the target start, or it may be rotating against the wind in the opposite direction, creating complex belt-speed start conditions. Currently, various belt-speed start technologies have emerged in the industry, enabling position and speed recognition under specific operating conditions, supporting the motor to complete belt-speed restart.

[0003] However, back-EMF-based observation methods have limited accuracy in the low-speed range, are easily affected by motor parameter drift and sampling noise, and struggle to cover the starting requirements across the entire speed range. Methods based on high-frequency signal injection have complex control logic, and the injected signal introduces additional current harmonics and electromagnetic noise, affecting the smoothness of motor operation. Most existing pulse detection-based methods do not finely differentiate between motor speed states; direct starting in headwind conditions can cause significant current surges and torque fluctuations, potentially triggering overcurrent protection and causing start-up failure. In low-speed tailwind conditions, where the motor speed is close to zero but not completely stopped, direct starting can easily lead to speed asynchrony and loss of synchronization. In medium-to-high-speed tailwind conditions, when there is a deviation between the initial position and speed observation, the start-up switching process can cause significant torque jumps, resulting in mechanical shock to the load. Starting characteristics vary considerably across different rotational directions and speed ranges; a uniform starting strategy cannot simultaneously ensure both starting smoothness and reliability under different operating conditions. Problems such as current surges, torque oscillations, and start-up failures during headwind starting remain difficult to effectively address. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention discloses a position-sensorless headwind / tailwind start method applied to a permanent magnet synchronous motor (PMSM), comprising: Step S1, applying continuous first-type vector pulses to the PMSM to determine the current vector position and initial speed observation value of the PMSM; Step S2, determining the initial operating state of the PMSM based on the initial speed observation value, and processing the PMSM according to the initial operating state: when the initial operating state indicates that the rotor of the PMSM is rotating against the wind, braking the rotor and starting the PMSM; when the initial operating state indicates that the rotor of the PMSM is rotating with the wind, proceeding to Step S3: Step S3, processing the initial current amplitude based on the initial speed observation value, and judging based on the initial current amplitude: if the PMSM... The rotor speed of the machine is in the first rotational state. After waiting for the load of the permanent magnet synchronous motor to stop naturally, the permanent magnet synchronous motor is started. If the rotor speed of the permanent magnet synchronous motor is in the second rotational state, then proceed to step S4: Step S4, apply continuous second type vector pulses to the permanent magnet synchronous motor to update the current vector position and speed observation value. Determine the initial calibration position of the rotor based on the updated current vector position, determine the initial calibration speed of the rotor based on the updated speed observation value, and start the permanent magnet synchronous motor according to the initial calibration position and the initial calibration speed. The speed of the rotor in the first rotational state is lower than the speed of the rotor in the second rotational state. The pulse duration of the first type vector pulse is fixed. The pulse duration of the second type vector pulse is determined based on the current current vector position and the current current amplitude.

[0005] Preferably, the first type of vector pulse includes a first pulse and a second pulse; the current vector position includes a first current vector position and a second current vector position; step S1 includes: step S11, applying the first pulse to the permanent magnet synchronous motor to obtain the first stator current signal of the permanent magnet synchronous motor; step S12, processing the first stator current signal based on Clark transform to obtain the first... Axial components and first Axis component, according to the first Axis component and the first The shaft component determines the position of the first current vector; step S13, the second pulse is applied to the permanent magnet synchronous motor to obtain the second stator current signal of the permanent magnet synchronous motor; step S14, the second stator current signal is processed based on Clarke transform to obtain the second... Axial component and second Axis component, according to the second Axis component and the second The shaft component determines the position of the second current vector; step S15, the initial rotational speed observation value is obtained by processing the first current vector position, the second current vector position and the pulse interval between the first pulse and the second pulse.

[0006] Preferably, the initial rotational speed observation value is calculated using the following formula:

[0007] in, The initial rotational speed observation value; This is the position of the second current vector; The position of the first current vector; The pulse interval between the first pulse and the second pulse.

[0008] Preferably, step S3 includes: step S31, obtaining the corresponding initial current amplitude based on the observed initial speed, the preset motor flux linkage constant, the pulse duration of the first type of vector pulse, and the q-axis inductance of the permanent magnet synchronous motor; step S32, determining the medium-high speed critical speed of the permanent magnet synchronous motor based on the preset rated motor speed, and determining the critical current amplitude based on the motor flux linkage constant, the pulse duration of the first type of vector pulse, the q-axis inductance, and the medium-high speed critical speed; step S33, determining whether the initial current amplitude is less than the critical current amplitude: if yes, the initial operating state indicates that the rotor of the permanent magnet synchronous motor is in the first rotating state, and the permanent magnet synchronous motor is started after the load of the permanent magnet synchronous motor naturally stops; if no, the initial operating state indicates that the rotor of the permanent magnet synchronous motor is in the second rotating state.

[0009] Preferably, when the initial operating state is represented by the rotor of the permanent magnet synchronous motor rotating against the wind, the inverter continuously outputs a braking signal to the permanent magnet synchronous motor to reduce the observed speed value until the current observed speed value of the rotor is less than a preset safe speed threshold, after which the braking signal is stopped and the permanent magnet synchronous motor is started.

[0010] Preferably, the first type of vector pulse includes a first pulse and a second pulse; the second type of vector pulse includes a third pulse and a fourth pulse; the current vector position includes a first current vector position corresponding to the first pulse, a second current vector position corresponding to the second pulse, a third current vector position corresponding to the third pulse, and a fourth current vector position corresponding to the fourth pulse; the speed observation value includes a second speed observation value and a third speed observation value; step S4 includes: step S41, applying the third pulse to the permanent magnet synchronous motor and determining the third current vector position based on the third pulse; step S42, processing the second current vector position, the third current vector position, and the pulse interval between the second pulse and the third pulse to obtain the second speed observation value; step S43, applying the fourth pulse to the permanent magnet synchronous motor and determining the fourth current vector position based on the fourth pulse; step S4 ...4, processing the second current vector position, the third current vector position, and the third current vector position based on the third pulse; step S45, processing the second current vector position, the third current vector position, and the third current vector position based on the third pulse; step S46, processing the second current vector position, the third current vector position, and the third current vector position based on the third pulse; step S47, processing the second current vector position, the third current vector position, and the third current vector position based on the third pulse; step S48, processing the second current vector position, the third current vector position, and the third current vector position based on the third pulse; step S49, processing the second current vector position, the third current vector position, and the third current vector position based on the third pulse; step S40, processing the second current vector position, the third current vector position, and the third current vector position based on the third pulse The third rotational speed observation value is obtained by processing the three current vector positions, the fourth current vector position, and the pulse interval between the third pulse and the fourth pulse; Step S45: Determine the first position observation value corresponding to the first current vector position, the second position observation value corresponding to the second current vector position, the third position observation value corresponding to the third current vector position, and the fourth position observation value corresponding to the fourth current vector position, respectively; fit the first position observation value, the second position observation value, the third position observation value, and the fourth position observation value to obtain the position curve; and fit the second rotational speed observation value and the third rotational speed observation value to obtain the rotational speed curve; Step S46: Determine the initial calibration position according to the position curve and the preset calibration time; determine the initial calibration speed according to the rotational speed curve and the calibration time; and start the permanent magnet synchronous motor according to the initial calibration position and the initial calibration speed.

[0011] Preferably, the pulse duration of the second type of vector pulse is determined using the following steps: Step B1, continuously apply the second type of vector pulse to the permanent magnet synchronous motor, and collect the corresponding current vector position within each preset sampling interval until the current vector position is collected a preset number of times, then proceed to step B2; Step B2, fit all current vector positions to obtain a first fitting curve, and fit all current vector positions excluding the last sampled current vector position to obtain a second fitting curve; Step B3, determine the first zero-point position based on the first fitting curve, and determine the second zero-point position based on the second fitting curve; Step B4, determine the current vector position based on the last two sampled current vector positions. The position and the sampling interval determine the current rotational speed observation value. Based on the corresponding rotational speed observation value, the current current amplitude is obtained. It is determined whether the current current amplitude is greater than the preset maximum current amplitude. If yes, the application of the second type of vector pulse is stopped, and the current first zero point position is used as the current vector position of the corresponding second type of vector pulse. If no, proceed to step B5. In step B5, it is determined whether the difference between the first zero point position and the second zero point position is not greater than the preset critical allowable value. If yes, the application of the second type of vector pulse is stopped, and the current first zero point position is used as the current vector position of the corresponding second type of vector pulse. If no, the next sampling is performed, and then the process returns to step B2.

[0012] Preferably, the current amplitude is calculated using the following formula:

[0013] in, The current amplitude; The flux linkage constant of the motor is denoted as . The pulse injection width; This is the current observed rotational speed; Let be the q-axis inductance.

[0014] Preferably, after determining the initial calibration position and the initial calibration speed, the following steps are performed: Step C1, a synchronous rotating coordinate system is established using the initial calibration position and the initial calibration speed, and open-loop control of the permanent magnet synchronous motor is performed based on the synchronous rotating coordinate system; Step C2, a sliding mode observer is used to output the predicted position and predicted speed of the permanent magnet synchronous motor in each preset output cycle, and it is determined whether the following conditions are met simultaneously: the difference between the predicted position and the initial calibration position is not greater than a preset position error threshold, and the difference between the predicted speed and the initial calibration speed is not greater than a preset speed error threshold; if yes, the predicted position and predicted speed output by the sliding mode observer are used to perform closed-loop control of the permanent magnet synchronous motor; if no, the next output cycle is waited for the next round of judgment.

[0015] The present invention achieves the following beneficial effects: by applying continuous vector pulses to the permanent magnet synchronous motor to determine the current vector position and speed observation value, the current amplitude is obtained based on the speed observation value and the initial operating state of the motor is determined. For three different initial states—headwind rotation, tailwind low-speed rotation, and tailwind medium-high-speed rotation—corresponding starting processing methods are matched. In the tailwind medium-high-speed state, the position and speed observation data are updated, and the initial position and speed are fitted to complete the start-up. This solves the problems of existing belt speed start-up schemes being unable to adapt to different rotation directions and speed ranges, easily generating current surges and torque oscillations, and having insufficient start-up reliability. It effectively reduces current surges and mechanical torque fluctuations during headwind and tailwind start-up processes, improves the operational stability of the belt speed start-up process, broadens the applicable operating conditions range of sensorless control, and improves the start-up success rate and long-term operational reliability under complex belt speed conditions. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of the headwind and tailwind start-up method without position sensors in this invention; Figure 2 This is a schematic diagram of the process for determining the observed rotational speed value in this invention; Figure 3 This is a schematic diagram of the process for determining the initial operating state in this invention; Figure 4 This is a schematic diagram of the process for starting a permanent magnet synchronous motor under tailwind and high-speed conditions in this invention; Figure 5 This is a schematic diagram of the process of applying the second type of vector pulse in this invention; Figure 6 This is a schematic diagram of the alternating open-loop control and closed-loop control process in this invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0020] This invention discloses a position-sensorless method for starting in both directions of wind, applicable to permanent magnet synchronous motors, such as... Figure 1 As shown, the process includes: Step S1, applying continuous first-type vector pulses to the permanent magnet synchronous motor to determine the current vector position and initial speed observation value of the permanent magnet synchronous motor; Step S2, determining the initial operating state of the permanent magnet synchronous motor based on the initial speed observation value, and processing the permanent magnet synchronous motor according to the initial operating state: when the initial operating state is represented by the rotor of the permanent magnet synchronous motor rotating against the wind, braking the rotor and starting the permanent magnet synchronous motor; when the initial operating state is represented by the rotor of the permanent magnet synchronous motor rotating with the wind, proceeding to Step S3: Step S3, obtaining the initial current amplitude based on the initial speed observation value, and judging based on the initial current amplitude: if the rotor speed of the permanent magnet synchronous motor is in the first rotation state, waiting for the permanent magnet synchronous motor to start. After the stepper motor's load naturally stops, the permanent magnet synchronous motor is started. If the rotor speed of the permanent magnet synchronous motor is in the second rotational state, then proceed to step S4: In step S4, continuous second-type vector pulses are applied to the permanent magnet synchronous motor to update the current vector position and speed observation value. Based on the updated current vector position, the initial calibration position of the rotor is determined, and based on the updated speed observation value, the initial calibration speed of the rotor is determined. The permanent magnet synchronous motor is started according to the initial calibration position and the initial calibration speed. The rotor speed in the first rotational state is lower than the rotor speed in the second rotational state. The pulse duration of the first-type vector pulse is fixed. The pulse duration of the second-type vector pulse is determined based on the current current vector position and the current current amplitude.

[0021] Specifically, the position-sensorless headwind and tailwind starting method of this application is realized by employing a control system of a permanent magnet synchronous motor. This control system includes at least a permanent magnet synchronous motor, a three-phase inverter, a current sampling module, a controller, a zero-voltage vector injection module, a sliding mode observer, and a vector control module.

[0022] Both the first and second type vector pulses are zero-voltage vector pulses.

[0023] Specifically, the three-phase output terminals of the inverter are at the same potential, and the three-phase windings of the motor stator form a closed short-circuit circuit.

[0024] In a preferred embodiment of the present invention, the first type of vector pulse includes a first pulse and a second pulse; the current vector position includes a first current vector position and a second current vector position; as shown... Figure 2 As shown, step S1 includes: step S11, applying a first pulse to the permanent magnet synchronous motor to obtain a first stator current signal of the permanent magnet synchronous motor; step S12, processing the first stator current signal based on the Clarke transform to obtain a first... Axial components and first Axis components, according to the first Axial components and first The shaft component determines the position of the first current vector; step S13, a second pulse is applied to the permanent magnet synchronous motor to obtain the second stator current signal of the permanent magnet synchronous motor; step S14, the second stator current signal is processed based on the Clarke transform to obtain the second... Axial component and second Axis components, according to the second Axial component and second The shaft component determines the position of the second current vector; in step S15, the initial rotational speed observation value is obtained by processing the first current vector position, the second current vector position and the pulse interval between the first pulse and the second pulse.

[0025] Specifically, in the closed short-circuit circuit formed by the three-phase stator windings of the motor, the permanent magnet magnetic field of the rotor rotating at high speed will induce a back electromotive force in the stator windings. This back electromotive force will excite a transient current in the short-circuited winding circuit, which serves as the stator current signal. Its amplitude is positively correlated with the motor speed, and its vector phase corresponds to the rotor position in real time.

[0026] When the controller outputs a zero-voltage vector pulse, it triggers the three-phase current sampling circuit in the control system. The first stator current signal is collected during the stable period of the first pulse through a Hall current sensor or a bridge arm sampling resistor, and the second stator current signal is collected during the stable period of the second pulse.

[0027] Furthermore, through Clarke transform, we obtain The current component in the coordinate system is expressed by the following formula:

[0028] in, The corresponding stator current signals include the first stator current signal and the second stator current signal; for The current components of the shaft, including the first Axial component and second Axial components; for The current components of the shaft, including the first Axial component and second Axial components.

[0029] The position of the corresponding current vector is calculated based on the current components using the following formula:

[0030] in, Let i be the position of the i-th current vector, including the first current vector position, the second current vector position, the third current vector position, and the fourth current vector position.

[0031] The direction of motor rotation is determined by the change in the position angle of the current vector before and after the zero-voltage vector pulse. Since the rotor flux linkage rotates continuously under belt speed, the current vector excited by the zero-voltage vector pulse also changes with the direction of rotor rotation.

[0032] In a preferred embodiment of the present invention, the initial observed rotational speed is calculated using the following formula:

[0033] in, These are the initial observed rotational speed values; The location of the second current vector; The location of the first current vector; The pulse interval between the first pulse and the second pulse.

[0034] Specifically, the initial rotational speed observation value is the average rotational speed between the first pulse and the second pulse.

[0035] To ensure the accuracy of the tan-1() function calculation, the rotor's electrical angle must be limited during the interval between two pulses. Within the range of (-180°, 180°) In a preferred embodiment of the present invention, such as Figure 3As shown, step S3 includes: step S31, obtaining the corresponding initial current amplitude based on the initial speed observation value, the preset motor flux linkage constant, the pulse duration of the first type of vector pulse, and the q-axis inductance of the permanent magnet synchronous motor; step S32, determining the medium-high speed critical speed of the permanent magnet synchronous motor based on the preset motor rated speed, and determining the critical current amplitude based on the motor flux linkage constant, the pulse duration of the first type of vector pulse, the q-axis inductance, and the medium-high speed critical speed; step S33, determining whether the initial current amplitude is less than the critical current amplitude: if yes, the initial operating state is represented as the rotor of the permanent magnet synchronous motor being in the first rotating state, and the permanent magnet synchronous motor being started after the load of the permanent magnet synchronous motor naturally stops; if no, the initial operating state is represented as the rotor of the permanent magnet synchronous motor being in the second rotating state.

[0036] Specifically, according to the principle of zero-voltage vector pulse method, the higher the motor speed, the greater its back electromotive force, and the more obvious the current response generated by zero-voltage vector pulse excitation. Therefore, the current amplitude can be used as the criterion for speed range.

[0037] In one embodiment, the initial current amplitude is calculated using the following formula:

[0038] in, This is the initial current amplitude; For the corresponding Current components of the shaft; For the corresponding Current component of the shaft.

[0039] In one embodiment, since the pulse signals applied in this application are all zero-voltage pulses, the initial current amplitude is calculated using the following formula:

[0040] in, This is the initial current amplitude; Let f be the motor flux linkage constant; The pulse injection width; These are the initial observed rotational speed values; It is the q-axis inductance.

[0041] The critical speed for medium and high speeds is determined using the following formula:

[0042] in, This is the critical speed for medium to high speeds; This is the rated speed of the motor.

[0043] Subsequently, the critical current amplitude is determined using the following formula:

[0044] in, This is the critical current amplitude.

[0045] In addition, when it is necessary to determine the mechanical speed of the motor rotor, the following formula is used for calculation:

[0046] in, The mechanical speed of the motor rotor; This is the current observed rotational speed; This represents the number of pole pairs of the motor.

[0047] Furthermore, the initial current amplitude is compared with the critical current amplitude. When the initial current amplitude is less than the critical current amplitude, the initial operating state is represented by the rotor of the permanent magnet synchronous motor being in the first rotating state, indicating that the rotor is rotating at low speed in the wind. When the initial current amplitude is not less than the critical current amplitude, the initial operating state is represented by the rotor of the permanent magnet synchronous motor being in the second rotating state, indicating that it is rotating at medium to high speed in the wind.

[0048] In a preferred embodiment of the present invention, when the rotor of the permanent magnet synchronous motor is rotating against the wind in the initial operating state, the inverter continuously outputs a braking signal to the permanent magnet synchronous motor to reduce the observed speed value until the current observed speed value of the rotor is less than a preset safe speed threshold, and then stops outputting the braking signal, and then starts the permanent magnet synchronous motor.

[0049] Specifically, when the motor is determined to be in a headwind condition, the controller enters the braking and deceleration phase. During the braking and deceleration phase, the controller outputs a braking control quantity opposite to the current rotation direction of the motor, causing the inverter to apply a limited-amplitude braking voltage vector or braking current command to the motor, thereby gradually reducing the motor speed.

[0050] Furthermore, braking is achieved using a voltage and current limiting method. The inverter output voltage vector amplitude does not exceed a preset braking voltage threshold, and during current limiting, the motor stator current amplitude does not exceed a preset maximum stator current threshold. If the stator current amplitude is detected to reach or exceed the preset maximum stator current threshold during braking, the controller reduces the braking voltage amplitude or pauses the PWM output, and resumes braking after the current decreases. If the DC bus voltage is detected to exceed a preset bus voltage protection threshold, the braking output is reduced or the braking state is exited to avoid bus overvoltage.

[0051] In a preferred embodiment of the present invention, the first type of vector pulse includes a first pulse and a second pulse; the second type of vector pulse includes a third pulse and a fourth pulse; the current vector position includes a first current vector position corresponding to the first pulse, a second current vector position corresponding to the second pulse, a third current vector position corresponding to the third pulse, and a fourth current vector position corresponding to the fourth pulse; the speed observation value includes a second speed observation value and a third speed observation value; step S4 includes, when the initial operating state is represented as the rotor of the permanent magnet synchronous motor rotating at medium to high speed in a downwind direction, such as Figure 4 As shown, the following steps are performed: Step S41, apply a third pulse to the permanent magnet synchronous motor and determine the position of the third current vector based on the third pulse; Step S42, process the second current vector position, the third current vector position, and the pulse interval between the second and third pulses to obtain the second speed observation value; Step S43, apply a fourth pulse to the permanent magnet synchronous motor and determine the position of the fourth current vector based on the fourth pulse; Step S44, process the third current vector position, the fourth current vector position, and the pulse interval between the third and fourth pulses to obtain the third speed observation value; Step S45, determine the first speed observation value corresponding to the first current vector position. A position curve is obtained by fitting the first position observation value, the second position observation value corresponding to the second current vector position, the third position observation value corresponding to the third current vector position, and the fourth position observation value corresponding to the fourth current vector position; and a speed curve is obtained by fitting the second speed observation value and the third speed observation value; in step S46, the initial calibration position is determined according to the position curve and the preset calibration time, the initial calibration speed is determined according to the speed curve and the calibration time, and the permanent magnet synchronous motor is started according to the initial calibration position and the initial calibration speed.

[0052] Specifically, the third and fourth pulses are adjusted based on the initial speed observation value. While ensuring that the electrical angle rotated by the rotor within the interval between the two pulses does not exceed 180°, the pulse interval is increased as much as possible to reduce the relative error of speed observation.

[0053] Furthermore, during the application of the third and fourth pulses, the corresponding stator current signals are continuously acquired through a sampling circuit. The stator current signals obtained from each sampling are then decomposed using Clarke transform. Current components of the shaft and The current components of the shaft are used to obtain the corresponding current vector positions. The current vector positions obtained from two adjacent sampling intervals are processed to obtain the corresponding rotational speed observations. In addition, the preset current phase angle is subtracted from each current vector position to obtain the corresponding position observations. The four position observations are fitted to obtain the position curve, and the two rotational speed observations are fitted to obtain the rotational speed curve.

[0054] In one embodiment, assuming that the first pulse is applied at the first moment and the fourth pulse is applied at the fourth moment, the position observation value of the position curve at the fifth moment is taken as the initial calibration position, and the speed observation value of the speed curve at the fifth moment is taken as the initial calibration speed.

[0055] In a preferred embodiment of the present invention, such as Figure 5 As shown, the pulse duration of the second type of vector pulse is determined using the following steps: Step B1, continuously apply the second type of vector pulse to the permanent magnet synchronous motor, and collect the corresponding current vector position within each preset sampling interval until the current vector position is collected a preset number of times, then proceed to step B2; Step B2, fit all current vector positions to obtain a first fitting curve, and fit all current vector positions excluding the last sampled current vector position to obtain a second fitting curve; Step B3, determine the first zero-point position based on the first fitting curve, and determine the second zero-point position based on the second fitting curve; Step B4, determine the current vector position based on the last two sampled current vector positions. The position and sampling interval determine the current rotational speed observation value. Based on the corresponding rotational speed observation value, the current current amplitude is obtained. It is then determined whether the current current amplitude is greater than the preset maximum current amplitude. If yes, the application of the second type of vector pulse is stopped, and the current first zero point position is used as the current vector position of the corresponding second type of vector pulse. If no, proceed to step B5. In step B5, it is determined whether the difference between the first zero point position and the second zero point position is not greater than the preset critical allowable value. If yes, the application of the second type of vector pulse is stopped, and the current first zero point position is used as the current vector position of the corresponding second type of vector pulse. If no, the next sampling is performed, and then the process returns to step B2.

[0056] Specifically, the second type of vector pulse includes a third pulse and a fourth pulse, and the above steps are performed when the third pulse and the fourth pulse are applied.

[0057] During each sampling, the corresponding stator current signal is acquired, and the stator current signal is decomposed into the corresponding current components to obtain the corresponding current vector position. The process has been described in detail above and will not be repeated here.

[0058] In one embodiment, the preset number of times is three. A first fitting curve and a second fitting curve are obtained by fitting the current vector positions from the three samplings and the current vector positions from the first two samplings, respectively. The first zero-point position corresponding to the first fitting curve and the second zero-point position corresponding to the second fitting curve when the sampling time is 0 are used to represent the current vector position at the pulse zero point of the corresponding pulse.

[0059] After obtaining the first zero-point position and the second zero-point position, the corresponding rotational speed observation value is determined based on the current vector position and sampling interval of the last two samples. The corresponding current amplitude is obtained by processing the corresponding rotational speed observation value. If the corresponding current amplitude is greater than the preset maximum current amplitude, it means that the current is about to break down the circuit. Then, the application of the corresponding second type vector pulse is stopped, and the current first zero-point position is used as the current vector position of the corresponding second type vector pulse.

[0060] If the corresponding current amplitude is not greater than the maximum current amplitude, the difference between the first zero point position and the second zero point position is calculated, and the difference is compared with the critical allowable value. If the difference is not greater than the critical allowable value, the application of the corresponding second type vector pulse is stopped, and the current first zero point position is used as the current vector position of the corresponding second type vector pulse. If the difference is greater than the critical allowable value, the next round of sampling is performed, and then the above judgment is repeated.

[0061] In a preferred embodiment of the present invention, the current amplitude is calculated using the following formula:

[0062] in, This refers to the current amplitude. Let f be the motor flux linkage constant; The pulse injection width; The corresponding observed rotational speed; It is the q-axis inductance.

[0063] In a preferred embodiment of the present invention, after determining the initial calibration position and the initial calibration speed, as follows: Figure 6As shown, the following steps are performed: Step C1, a synchronous rotating coordinate system is established using the initial calibration position and initial calibration speed, and open-loop control of the permanent magnet synchronous motor is performed based on the synchronous rotating coordinate system; Step C2, the predicted position and predicted speed of the permanent magnet synchronous motor are output by the sliding mode observer in each preset output cycle, and it is determined whether the following conditions are met simultaneously: the difference between the predicted position and the initial calibration position is not greater than the preset position error threshold, and the difference between the predicted speed and the initial calibration speed is not greater than the preset speed error threshold; if yes, the predicted position and predicted speed output by the sliding mode observer are used to perform closed-loop control of the permanent magnet synchronous motor; if no, the next output cycle is waited for the next round of judgment.

[0064] Specifically, the controller uses the initial calibrated position and initial calibrated speed as the initial continuous values ​​of the control system to establish a synchronous rotating coordinate system, and performs open-loop control of the permanent magnet synchronous motor based on the synchronous rotating coordinate system.

[0065] The controller uses the initial calibrated position as the initial angle of the synchronous rotating coordinate system and the initial calibrated speed as the initial rotational speed of the coordinate system. It continuously accumulates and calculates the rotor's position observation value at the current moment according to a fixed slope. Based on the calculated position observation value, it establishes a dq coordinate system that rotates approximately synchronously with the rotor. The real-time sampled three-phase stator current is converted into dq-axis DC through Clarke and Park transformations. The d-axis current is set to 0 and the q-axis current is set to a small torque holding current. The dq-axis voltage command is output through the current PI regulator. Then, the inverter switching signal is generated through inverse Park transformation and SVPWM modulation. The output voltage vector rotates synchronously with the rotor, allowing the load of the permanent magnet synchronous motor to rotate smoothly.

[0066] Furthermore, the sliding mode observer acquires the three-phase voltage and three-phase current of the permanent magnet synchronous motor in real time, and then iteratively calculates the back electromotive force estimate to output the predicted position and predicted speed. In the initial stage of the observer's startup, due to the unstable state, the estimated value deviates from the actual value, so the output does not participate in the closed-loop control, but only continuously updates iteratively.

[0067] The position error threshold is determined based on the allowable rotor position observation error of the motor.

[0068] In one embodiment, the position error threshold is set to 10° electrical angle.

[0069] The speed error threshold is determined based on the motor's rated speed.

[0070] In one embodiment, the speed error threshold is set to 1% of the motor's rated speed.

[0071] After using a sliding mode observer for closed-loop control, the controller uses the predicted position output by the sliding mode observer as the angle of the Park transform and inverse Park transform, and uses the predicted speed output by the sliding mode observer as the speed feedback value.

[0072] Specifically, the controller collects the three-phase stator current of the motor and obtains the current components in the αβ stationary coordinate system through Clarke transformation; then, based on the predicted position output by the sliding mode observer, Park transformation is performed to obtain the d-axis current and q-axis current.

[0073] In the speed loop, the controller obtains the q-axis current setpoint through the speed PI regulator based on the deviation between the target speed and the predicted speed output by the sliding mode observer. At the same time, the d-axis current setpoint can be set to 0.

[0074] Subsequently, the controller calculates the difference between the d-axis current and the d-axis current setpoint, as well as the difference between the q-axis current and the q-axis current setpoint. Based on the deviation between the two differences, the d-axis voltage setpoint and the q-axis voltage setpoint are obtained through the d-axis and q-axis current PI regulators, respectively.

[0075] Finally, the controller performs an inverse Park transform on the d-axis and q-axis voltage setpoints based on the predicted position output by the sliding mode observer, to obtain... The voltage command in the stationary coordinate system is used to generate inverter switching signals through SVPWM (Space Vector Pulse Width Modulation) to drive the permanent magnet synchronous motor to operate stably.

[0076] Since the position and speed remain continuous before and after the switch, no significant current surge or torque change occurs during the entire switching process, thus achieving smooth and uninterrupted start-up of the permanent magnet synchronous motor under both headwind and tailwind conditions.

[0077] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious transformations made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A position-sensorless method for starting under wind and in the opposite direction, applied to a permanent magnet synchronous motor, characterized in that, include: Step S1: Apply continuous first-type vector pulses to the permanent magnet synchronous motor to determine the current vector position and initial speed observation value of the permanent magnet synchronous motor; Step S2: Determine the initial operating state of the permanent magnet synchronous motor based on the initial speed observation value, and process the permanent magnet synchronous motor according to the initial operating state: When the initial operating state indicates that the rotor of the permanent magnet synchronous motor is rotating against the wind, brake the rotor and start the permanent magnet synchronous motor; when the initial operating state indicates that the rotor of the permanent magnet synchronous motor is rotating with the wind, proceed to step S3: Step S3: Obtain the initial current amplitude based on the initial speed observation value, and make a judgment based on the initial current amplitude: If the rotor speed of the permanent magnet synchronous motor is in the first rotation state, wait for the load of the permanent magnet synchronous motor to stop naturally and then start the permanent magnet synchronous motor; If the rotor speed of the permanent magnet synchronous motor is in the second rotation state, then proceed to step S4: Step S4, apply continuous second type vector pulses to the permanent magnet synchronous motor to update the current vector position and speed observation value, determine the initial calibration position of the rotor based on the updated current vector position, determine the initial calibration speed of the rotor based on the updated speed observation value, and start the permanent magnet synchronous motor according to the initial calibration position and the initial calibration speed; The rotor's rotational speed in the first rotational state is lower than the rotor's rotational speed in the second rotational state; the pulse duration of the first type of vector pulse is fixed; the pulse duration of the second type of vector pulse is determined based on the current current vector position and the current current amplitude.

2. The position-sensorless headwind and tailwind start-up method according to claim 1, characterized in that, The first type of vector pulse includes a first pulse and a second pulse; the current vector position includes a first current vector position and a second current vector position; step S1 includes: step S11, applying the first pulse to the permanent magnet synchronous motor to obtain the first stator current signal of the permanent magnet synchronous motor; step S12, processing the first stator current signal based on Clark transform to obtain the first... Axial components and first Axis component, according to the first Axis component and the first The shaft component determines the position of the first current vector; step S13, the second pulse is applied to the permanent magnet synchronous motor to obtain the second stator current signal of the permanent magnet synchronous motor; step S14, the second stator current signal is processed based on Clarke transform to obtain the second... Axial component and second Axis component, according to the second Axis component and the second The shaft component determines the position of the second current vector; step S15, the initial rotational speed observation value is obtained by processing the first current vector position, the second current vector position and the pulse interval between the first pulse and the second pulse.

3. The position-sensorless headwind and tailwind start-up method according to claim 2, characterized in that, The initial rotational speed observation value was calculated using the following formula: ； in, The initial rotational speed observation value; The location of the second current vector; The position of the first current vector; The pulse interval between the first pulse and the second pulse.

4. The position-sensorless headwind and tailwind start-up method according to claim 1, characterized in that, Step S3 includes: Step S31, obtaining the corresponding initial current amplitude based on the initial speed observation value, the preset motor flux linkage constant, the pulse duration of the first type of vector pulse, and the q-axis inductance of the permanent magnet synchronous motor; Step S32, determining the medium-high speed critical speed of the permanent magnet synchronous motor based on the preset motor rated speed, and determining the critical current amplitude based on the motor flux linkage constant, the pulse duration of the first type of vector pulse, the q-axis inductance, and the medium-high speed critical speed; Step S33, determining whether the initial current amplitude is less than the critical current amplitude: if yes, the initial operating state indicates that the rotor of the permanent magnet synchronous motor is in the first rotating state, and the permanent magnet synchronous motor is started after the load of the permanent magnet synchronous motor naturally stops; if no, the initial operating state indicates that the rotor of the permanent magnet synchronous motor is in the second rotating state.

5. The position-sensorless headwind and tailwind start-up method according to claim 1, characterized in that, When the initial operating state is represented by the rotor of the permanent magnet synchronous motor rotating against the wind, the inverter continuously outputs a braking signal to the permanent magnet synchronous motor to reduce the observed speed value until the current observed speed value of the rotor is less than a preset safe speed threshold, then the braking signal is stopped, and the permanent magnet synchronous motor is started.

6. The position-sensorless headwind and tailwind start-up method according to claim 1, characterized in that, The first type of vector pulse includes a first pulse and a second pulse; the second type of vector pulse includes a third pulse and a fourth pulse; the current vector position includes a first current vector position corresponding to the first pulse, a second current vector position corresponding to the second pulse, a third current vector position corresponding to the third pulse, and a fourth current vector position corresponding to the fourth pulse; the rotational speed observation value includes a second rotational speed observation value and a third rotational speed observation value; Step S4 includes: Step S41, applying the third pulse to the permanent magnet synchronous motor and determining the position of the third current vector based on the third pulse; Step S42, processing the second current vector position, the third current vector position, and the pulse interval between the second and third pulses to obtain the second speed observation value; Step S43, applying the fourth pulse to the permanent magnet synchronous motor and determining the position of the fourth current vector based on the fourth pulse; Step S44, processing the third current vector position, the fourth current vector position, and the pulse interval between the third and fourth pulses to obtain the third speed observation value; Step S45, determining the third speed observation value corresponding to the first current vector position. A position observation value, a second position observation value corresponding to the second current vector position, a third position observation value corresponding to the third current vector position, and a fourth position observation value corresponding to the fourth current vector position are fitted together to obtain the position curve; and a speed curve is obtained by fitting the second speed observation value and the third speed observation value; step S46: the initial calibration position is determined according to the position curve and a preset calibration time, the initial calibration speed is determined according to the speed curve and the calibration time, and the permanent magnet synchronous motor is started according to the initial calibration position and the initial calibration speed.

7. The position-sensorless headwind and tailwind start-up method according to claim 1, characterized in that, The pulse duration of the second type of vector pulse is determined by the following steps: Step B1, the second type of vector pulse is continuously applied to the permanent magnet synchronous motor, and the corresponding current vector position is collected in each preset sampling interval until the current vector position is collected a preset number of times, then proceed to step B2; Step B2, all current vector positions are fitted to obtain a first fitting curve, and all current vector positions except the last sampled current vector position are fitted to obtain a second fitting curve; Step B3: Determine the first zero-point position based on the first fitted curve, and determine the second zero-point position based on the second fitted curve. Step B4: Determine the current rotational speed observation value based on the current vector position of the last two samples and the sampling interval. Process the corresponding rotational speed observation value to obtain the current current amplitude. Determine whether the current current amplitude is greater than the preset maximum current amplitude: if yes, stop applying the second type of vector pulse and use the current first zero-point position as the current vector position of the corresponding second type of vector pulse; if no, proceed to step B5. Step B5: Determine whether the difference between the first zero-point position and the second zero-point position is not greater than the preset critical allowable value: if yes, stop applying the second type of vector pulse and use the current first zero-point position as the current vector position of the corresponding second type of vector pulse; if no, perform the next sampling and then return to step B2.

8. The position-sensorless headwind and tailwind start-up method according to claim 7, characterized in that, The current amplitude is calculated using the following formula: ； in, The current amplitude; The flux linkage constant of the motor is denoted as . The pulse injection width; This is the current observed rotational speed; Let be the q-axis inductance.

9. The position-sensorless headwind and tailwind start-up method according to claim 1, characterized in that, After determining the initial calibration position and the initial calibration speed, the following steps are performed: Step C1, a synchronous rotating coordinate system is established using the initial calibration position and the initial calibration speed, and open-loop control of the permanent magnet synchronous motor is performed based on the synchronous rotating coordinate system; Step C2, a sliding mode observer is used to output the predicted position and predicted speed of the permanent magnet synchronous motor in each preset output cycle, and it is determined whether the following conditions are met simultaneously: the difference between the predicted position and the initial calibration position is not greater than a preset position error threshold, and the difference between the predicted speed and the initial calibration speed is not greater than a preset speed error threshold; if yes, the predicted position and predicted speed output by the sliding mode observer are used to perform closed-loop control of the permanent magnet synchronous motor; if no, the next output cycle is waited for the next round of judgment.

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