A heavy load starting method of a sensorless brushless motor for a photovoltaic tracker

Abstract

The application discloses a heavy-load starting method of a brushless motor without a position sensor for a photovoltaic tracker, and comprises the following steps: analyzing a motion instruction of the photovoltaic tracker and identifying the instruction type, and matching a suitable heavy-load starting parameter group according to the instruction type; in a position sensor-free control mode, generating and executing a motor initial angle control instruction, and completing motor pre-positioning control according to a predetermined position parameter in the heavy-load starting parameter group; entering a current-limited open-loop traction stage, synchronously collecting a bus voltage drop amplitude, a phase current, an estimated speed direction, an estimated electric angle and an open-loop operation duration; and comprehensively judging a motor heavy-load starting state based on multi-dimensional operation data. The application solves the problem that the existing heavy-load starting method of the brushless motor without the position sensor only has basic logics such as motor initial positioning, open-loop strong dragging, speed threshold value switching closed loop and the like, and is not suitable for working conditions such as photovoltaic tracker tracking, zero returning, wind avoiding and snow accumulation recovering, thereby leading to a low motor restart success rate.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic tracker technology, specifically a method for heavy-load starting of a brushless motor without position sensors for photovoltaic trackers. Background Technology

[0002] Photovoltaic trackers typically employ a low-speed, intermittent drive method to power large-area photovoltaic module arrays. During operation, their actuators continuously withstand multiple loads, including module gravity torque, site slope, wind load, snow accumulation, icing, dust accumulation causing jamming, and static friction from the gearbox. After prolonged periods of inactivity, the starting resistance of the photovoltaic tracker significantly exceeds that under normal tracking conditions. To reduce costs, increase efficiency, and improve overall reliability, photovoltaic tracker actuators generally forgo position detection devices such as Hall sensors and encoders, opting instead for sensorless brushless motors as the drive unit. However, existing heavy-load starting methods for sensorless brushless motors only address basic logic design such as initial positioning, open-loop forced drag, and closed-loop speed threshold switching for the motor itself. They fail to adapt and optimize for typical operating scenarios such as tracking angle adjustment, mechanical zeroing, wind and hazard avoidance, and snow recovery, ultimately resulting in a low motor restart success rate. Summary of the Invention

[0003] To address the aforementioned shortcomings, this invention proposes a sensorless brushless motor heavy-load start method for photovoltaic trackers. The aim is to solve the problem that existing sensorless brushless motor heavy-load start methods only have basic logic such as initial motor positioning, open-loop strong drag, and speed threshold switching closed loop, and do not adapt to the working conditions of photovoltaic trackers such as tracking, zeroing, wind avoidance, and snow recovery, resulting in a low motor restart success rate.

[0004] To achieve this objective, the present invention adopts the following technical solution: A method for heavy-load starting of a sensorless brushless motor for a photovoltaic tracker includes the following steps: Step S1: Receive motion commands from the photovoltaic tracker, parse them, and obtain the command type and target motion direction; synchronously collect the downtime of the brushless motor and the cumulative number of start-up failures. The command type corresponds to different operating conditions of the photovoltaic tracker. Step S2: Based on the instruction type, the downtime of the brushless motor, and the cumulative number of start-up failures of the brushless motor, match the heavy-load start-up parameter group of the brushless motor under the current operating conditions of the photovoltaic tracker. The heavy-load start-up parameter group includes pre-positioning parameters. Step S3: Based on the sensorless control mode, generate and execute the initial angle control command for the brushless motor; Step S4: Perform pre-positioning control of the brushless motor according to the pre-positioning parameters of the brushless motor; Step S5: Generate the open-loop electrical angle and open-loop frequency change slope of the brushless motor, and collect the bus voltage drop amplitude, phase current, estimated speed direction, estimated electrical angle and open-loop running time of the brushless motor in real time. Step S6: Determine whether the following conditions are met simultaneously: the bus voltage drop amplitude of the brushless motor is less than or equal to the preset drop amplitude limit; the phase current of the brushless motor is less than or equal to the preset phase current threshold; the estimated speed direction of the brushless motor is the same as the target motion direction; the deviation between the estimated electrical angle and the open-loop electrical angle of the brushless motor is less than the preset electrical angle error threshold; the slope of the open-loop frequency change of the brushless motor is within the preset slope range; and the open-loop running length is greater than or equal to the preset duration threshold. If yes, the brushless motor restart is considered successful, and the brushless motor closed-loop operation control is initiated. If no, the brushless motor restart is considered unsuccessful, and the heavy-load start parameter group is corrected according to the type of brushless motor restart failure before retrying the start, or a brushless motor fault alarm signal is generated.

[0005] Preferably, in step S2, the heavy-load start-up parameter group further includes the open-loop frequency change slope, the closed-loop switching frequency window, the bus voltage drop limit, the allowed number of retry attempts, and the fault reporting type; the prepositioning parameters include the first prepositioning current, the second prepositioning current, and the prepositioning holding time.

[0006] Preferably, in step S3, the initial angle control command for the brushless motor specifically includes: performing a reset initialization operation on the position observer, speed loop, and current loop states of the brushless motor; using magnetic field alignment to preposition and give the direction of the initial excitation magnetic field; using the IPD pulse injection method to compare the current feedback response of each phase to determine the approximate sector where the brushless motor rotor is located; if residual speed of the brushless motor is detected, the direction of rotation of the brushless motor rotor is determined by combining the back EMF information and the operating state of the position observer, and it is verified whether the conditions for direct tracking start-up are met.

[0007] Preferably, step S4 specifically includes the following sub-steps: Step S41: Apply a first prepositioning current and maintain the prepositioning holding time to pull and engage the rotor of the brushless motor along the target motion direction; Step S42: Use a second prepositioning current and maintain the prepositioning holding time to establish the starting torque.

[0008] Preferably, in step S6, when it is determined that the brushless motor restart has failed, the heavy-load start parameter group is modified according to the type of brushless motor restart failure, and the restart is retried. Specifically, this includes the following sub-steps: when the type of brushless motor restart failure is mechanical jamming, the power output of the brushless motor is stopped, and the prepositioning hold time is extended after a preset delay; when the type of brushless motor restart failure is overload, the open-loop acceleration is reduced, and the prepositioning hold time is extended; when the type of brushless motor restart failure is insufficient power supply, the starting current is reduced, or the retry start process is terminated, and the system waits for power supply to be restored; when the type of brushless motor restart failure is open-loop start failure, the prepositioning control command is re-executed, and the open-loop frequency change slope is reduced; when the type of brushless motor restart failure is closed-loop switching failure, the brushless motor is returned to the stop state, and the open-loop running time is extended before retrying the start.

[0009] Preferably, the method further includes the following steps: establishing a data storage library; storing the matched heavy-load start parameter group, the cumulative number of start failures, and the types of brushless motor restart failures in the data storage library.

[0010] The technical solution provided by this invention may include the following beneficial effects: This solution first parses the motion commands from the photovoltaic tracker and identifies the command type, then matches a suitable heavy-load start-up parameter set. Subsequently, in sensorless control mode, it generates and executes the initial angle control command for the motor, and completes the motor's pre-positioning control based on the pre-positioning parameters within the heavy-load start-up parameter set. Next, it enters the current-limiting open-loop traction stage, simultaneously collecting multi-dimensional operational data such as bus voltage drop amplitude, phase current, estimated speed direction, estimated electrical angle, and open-loop running time. Finally, based on the comprehensive analysis of the multi-dimensional operational data, it determines the motor's heavy-load start-up status and executes corresponding handling strategies, achieving heavy-load start-up of the sensorless brushless motor. Compared to existing sensorless brushless motor heavy-load start-up methods that rely solely on motor positioning, open-loop forced traction, or speed threshold switching closed loops, this solution can adapt a dedicated heavy-load start-up parameter set to different operating conditions, such as photovoltaic tracker tracking angle adjustment, mechanical zeroing, wind and hazard avoidance, and snow recovery, effectively improving the restart success rate of the brushless motor. Attached Figure Description

[0011] Figure 1 This is a flowchart illustrating the steps of a sensorless brushless motor heavy-load start-up method for a photovoltaic tracker. Detailed Implementation

[0012] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0013] A method for heavy-load starting of a sensorless brushless motor for a photovoltaic tracker includes the following steps: Step S1: Receive motion commands from the photovoltaic tracker, parse them, and obtain the command type and target motion direction; synchronously collect the downtime of the brushless motor and the cumulative number of start-up failures. The command type corresponds to different operating conditions of the photovoltaic tracker. Step S2: Based on the instruction type, the downtime of the brushless motor, and the cumulative number of start-up failures of the brushless motor, match the heavy-load start-up parameter group of the brushless motor under the current operating conditions of the photovoltaic tracker. The heavy-load start-up parameter group includes pre-positioning parameters. Step S3: Based on the sensorless control mode, generate and execute the initial angle control command for the brushless motor; Step S4: Perform pre-positioning control of the brushless motor according to the pre-positioning parameters of the brushless motor; Step S5: Generate the open-loop electrical angle and open-loop frequency change slope of the brushless motor, and collect the bus voltage drop amplitude, phase current, estimated speed direction, estimated electrical angle and open-loop running time of the brushless motor in real time. Step S6: Determine whether the following conditions are met simultaneously: the bus voltage drop amplitude of the brushless motor is less than or equal to the preset drop amplitude limit; the phase current of the brushless motor is less than or equal to the preset phase current threshold; the estimated speed direction of the brushless motor is the same as the target motion direction; the deviation between the estimated electrical angle and the open-loop electrical angle of the brushless motor is less than the preset electrical angle error threshold; the slope of the open-loop frequency change of the brushless motor is within the preset slope range; and the open-loop running length is greater than or equal to the preset duration threshold. If yes, the brushless motor restart is considered successful, and the brushless motor closed-loop operation control is initiated. If no, the brushless motor restart is considered unsuccessful, and the heavy-load start parameter group is corrected according to the type of brushless motor restart failure before retrying the start, or a brushless motor fault alarm signal is generated.

[0014] This solution presents a sensorless brushless motor heavy-load start method for photovoltaic trackers, such as... Figure 1As shown, the first step is to receive and parse the motion commands issued by the photovoltaic tracker to obtain the command type and target motion direction. Simultaneously, the downtime and cumulative number of start-up failures of the brushless motor are collected. The command type corresponds to different operating conditions of the photovoltaic tracker. In this embodiment, by parsing the motion commands from the photovoltaic tracker, different operating conditions and target motion directions are identified. Simultaneously, the downtime and cumulative number of start-up failures of the brushless motor are collected, enabling the understanding of the current operating environment, stationary state, and historical start-up anomalies of the brushless motor. This provides comprehensive and reliable data support for subsequent matching of heavy-load start-up parameters for compatible brushless motors. Further explanation: the motion command types of the photovoltaic tracker include tracking angle adjustment, mechanical zeroing, wind and hazard avoidance, and snow recovery. The second step is to match the heavy-load start parameter group of the brushless motor under the current operating conditions of the photovoltaic tracker, based on the command type, the downtime of the brushless motor, and the cumulative number of start failures of the brushless motor. This heavy-load start parameter group includes pre-positioning parameters. In this embodiment, by matching the corresponding heavy-load start parameter group based on the command type, motor downtime, and cumulative number of start failures, it is possible to specifically adapt to different operating conditions of the photovoltaic tracker, such as tracking angle adjustment, mechanical zeroing, wind and hazard avoidance, and snow recovery. The third step is to generate and execute the initial angle control command of the brushless motor based on the sensorless control mode. In this embodiment, by generating and executing the initial angle control command of the brushless motor based on the sensorless control mode, it is possible to perform preliminary positioning constraints on the electric angle of the brushless motor rotor in advance, even without position feedback from the motor. The fourth step is to perform pre-positioning control of the brushless motor based on its pre-positioning parameters. In this embodiment, the pre-positioning parameters in the heavy-load start-up parameter group are called to perform pre-positioning control of the brushless motor. This allows the rotor to be stably pulled to the optimal initial start-up position before the brushless motor starts in open loop, avoiding rotor offset deviation caused by the static friction of the photovoltaic tracker. The fifth step is to generate the open-loop electrical angle and open-loop frequency change slope of the brushless motor, and to collect the bus voltage drop amplitude, phase current, estimated speed direction, estimated electrical angle, and open-loop running time of the brushless motor in real time. In this embodiment, by generating the open-loop electrical angle and open-loop frequency change slope of the brushless motor, smooth open-loop control of the brushless motor is achieved. By synchronously collecting the bus voltage drop amplitude, phase current, estimated speed direction, estimated electrical angle, and open-loop running time of the brushless motor, comprehensive and accurate data support is provided for the comprehensive judgment of the subsequent heavy-load start-up results of the brushless motor.The sixth step is to determine whether the following conditions are met simultaneously: the bus voltage drop amplitude of the brushless motor is less than or equal to a preset drop amplitude threshold; the phase current of the brushless motor is less than or equal to a preset phase current threshold; the estimated speed direction of the brushless motor is the same as the target motion direction; the deviation between the estimated electrical angle and the open-loop electrical angle of the brushless motor is less than a preset electrical angle error threshold; the slope of the open-loop frequency change of the brushless motor is within a preset slope range; and the open-loop running length is greater than or equal to a preset duration threshold. If yes, the brushless motor is determined to have restarted successfully, and closed-loop operation control of the brushless motor is initiated. If no, the brushless motor is determined to have restarted unsuccessfully, and the heavy-load start parameter group is corrected according to the type of brushless motor restart failure before retrying the start, or a brushless motor fault alarm signal is generated. In this embodiment, the preset drop amplitude limit is 10V, the preset phase current threshold is 25A, the preset electrical angle error threshold is 5°, the preset slope range is 2~8Hz / s, and the preset duration threshold is 0.8s. By comprehensively judging the heavy-load start-up status of brushless motors through multi-dimensional indicators, it can accurately identify various problems that occur during the heavy-load start-up process, such as overcurrent, sudden drop in bus voltage, direction deviation, electrical angle mismatch, and abnormal speed increase. After successful start-up, it promptly switches to closed-loop control to ensure high-precision and stable speed operation of the brushless motor afterwards; in case of start-up failure, it can adaptively correct the start-up parameters for retry or output a fault alarm according to the failure type, effectively improving the safety and stability of brushless motor operation.

[0015] This solution first parses the motion commands from the photovoltaic tracker and identifies the command type, then matches a suitable heavy-load start-up parameter set. Subsequently, in sensorless control mode, it generates and executes the initial angle control command for the motor, and completes the motor's pre-positioning control based on the pre-positioning parameters within the heavy-load start-up parameter set. Next, it enters the current-limiting open-loop traction stage, simultaneously collecting multi-dimensional operational data such as bus voltage drop amplitude, phase current, estimated speed direction, estimated electrical angle, and open-loop running time. Finally, based on the comprehensive analysis of the multi-dimensional operational data, it determines the motor's heavy-load start-up status and executes corresponding handling strategies, achieving heavy-load start-up of the sensorless brushless motor. Compared to existing sensorless brushless motor heavy-load start-up methods that rely solely on motor positioning, open-loop forced traction, or speed threshold switching closed loops, this solution can adapt a dedicated heavy-load start-up parameter set to different operating conditions, such as photovoltaic tracker tracking angle adjustment, mechanical zeroing, wind and hazard avoidance, and snow recovery, effectively improving the restart success rate of the brushless motor.

[0016] Preferably, in step S2, the overload start-up parameter group further includes the open-loop frequency change slope, the closed-loop frequency window, the bus voltage drop limit, the number of allowed retry attempts, and the fault reporting type; the prepositioning parameters include the first prepositioning current, the second prepositioning current, and the prepositioning holding time.

[0017] In this embodiment, by setting an appropriate open-loop frequency change slope, the problem of motor rotor step loss under heavy load conditions can be avoided. By setting an appropriate closed-loop cut-in frequency window, the operational stability of the position observer can be improved. By setting a bus voltage drop amplitude limit, the impact risk caused by forced motor start-up when power supply is insufficient can be avoided. By setting the allowed number of retries, the motor start-up success rate is improved while power device protection is achieved; by setting the fault reporting type, the photovoltaic tracker can easily perform a risk avoidance protection posture. By setting a first prepositioning current, the motor rotor can be engaged; by setting a second prepositioning current, a starting torque capable of overcoming static friction and snow loads can be established; by setting a prepositioning hold duration, sufficient force response buffer time is reserved for the mechanical loads of the photovoltaic tracker's gearbox, push rod, bracket, etc.

[0018] Preferably, in step S3, the initial angle control command for the brushless motor specifically includes: performing a reset initialization operation on the position observer, speed loop, and current loop states of the brushless motor; using magnetic field alignment for pre-positioning to give the initial excitation magnetic field direction; using the IPD pulse injection method to compare the current feedback responses of each phase to determine the approximate sector where the brushless motor rotor is located; if residual speed of the brushless motor is detected, combining the back EMF information and the operating state of the position observer to determine the direction of rotation of the brushless motor rotor, and verifying whether the conditions for direct tracking start-up are met.

[0019] In this embodiment, by resetting the position observer, speed loop, and current loop states of the brushless motor before startup, the accumulated errors, steady-state offsets, and disturbance parameters remaining from the previous operation can be effectively cleared. By using magnetic field alignment to pre-position the initial excitation magnetic field direction, the initial zero-point position of the brushless motor rotor can be quickly locked. By injecting small-amplitude high-frequency pulses to collect the current feedback differences of each phase, the sector where the brushless motor rotor is located can be accurately divided, effectively reducing the initial angle estimation error. When the brushless motor has residual speed, the actual direction of rotation of the rotor is determined by combining the back EMF information and the operating status of the position observer, and the feasibility of tracking startup is verified simultaneously. This can effectively improve the accuracy of direction recognition and prevent overcurrent, stalling, and other situations caused by reverse startup.

[0020] Preferably, step S4 specifically includes the following sub-steps: Step S41: Apply a first pre-positioning current and maintain it for a pre-positioning holding time to pull and engage the rotor of the brushless motor along the target motion direction; Step S42: Replace with a second pre-positioning current and maintain it for a pre-positioning holding time to establish starting torque. In this embodiment, in step S41, by applying a first pre-positioning current with a lower amplitude and coordinating it with a pre-positioning holding time, i.e., a force response buffer time, the rotor of the brushless motor is pulled and engaged to the initial zero position along the target motion direction, which can unify the electrical angle reference of the entire brushless motor. In step S42, by replacing with a second pre-positioning current with a higher amplitude and coordinating it with a pre-positioning holding time to establish starting torque, the static friction torque brought by the photovoltaic tracker's gearbox, push rod, and bracket, as well as the gravity load torque generated by snow accumulation, can be effectively offset.

[0021] Preferably, in step S6, when it is determined that the brushless motor restart has failed, the heavy-load start parameter group is modified according to the type of brushless motor restart failure, and the restart is retried. Specifically, this includes the following sub-steps: When the brushless motor restart failure is due to mechanical jamming, the brushless motor power output is stopped, and the pre-position hold time is extended after a preset delay. When the brushless motor restart failure is due to overload, the open-loop acceleration is reduced, and the pre-position hold time is extended. When the brushless motor restart failure is due to insufficient power supply, the starting current is reduced, or the retry start process is terminated, and the system waits for power supply to be restored. When the brushless motor restart failure is due to open-loop start failure, the pre-position control command is re-executed, and the open-loop frequency change slope is reduced. When the brushless motor restart failure is due to closed-loop switching failure, the brushless motor is returned to the stop state, and the open-loop running time is extended before retrying the start.

[0022] In this embodiment, the heavy-load start parameter group is precisely adjusted by different types of brushless motor restart failures to achieve targeted compensation optimization for brushless motor restart failures, thereby improving the success rate of secondary start-up of brushless motors under complex working conditions such as mechanical jamming, excessive load, insufficient power supply, open-loop start failure, and closed-loop switching failure.

[0023] To further explain, when the brushless motor restart failure is due to mechanical jamming, stopping the brushless motor power output can prevent the high current from burning out the brushless motor; extending the prepositioning hold time can slowly release the jamming resistance. When the brushless motor restart failure is due to overload, reducing the open-loop acceleration can prevent step loss and jitter caused by insufficient instantaneous acceleration torque; extending the prepositioning hold time can output sufficient prepositioning torque to preemptively support the heavy load. When the brushless motor restart failure is due to insufficient power supply, reducing the starting current allows for a small current to test the start-up, maximizing the continuous operation of the brushless motor; terminating the retry start-up process and waiting for power restoration can prevent a continuous high current from lowering the bus voltage, thus avoiding undervoltage damage to the brushless motor. When the brushless motor restart failure is due to open-loop start-up failure, re-performing the prepositioning process and reducing the open-loop frequency change slope can quickly eliminate phase deviation during the open-loop start-up process. When the failure type of brushless motor restart is closed-loop failure, the brushless motor can be stopped and the open-loop running time can be extended before restarting. This can avoid switching oscillation or loss of closed loop caused by large fluctuations in the rotor speed of the brushless motor and insufficient phase matching.

[0024] Preferably, the method further includes the following steps: establishing a data storage library; storing the matched heavy-load start-up parameter group, the cumulative number of start-up failures, and the brushless motor restart failure types in the data storage library. In this embodiment, the brushless motor controller is equipped with a non-volatile memory for storing data packets such as the matched heavy-load start-up parameter group, the cumulative number of start-up failures, and the brushless motor restart failure types. The stored data packets can be completely preserved in the power-off state and will not be lost. Further, the stored data packets contain built-in identifiers, version numbers, data lengths, entity parameters, and CRC check values. When the photovoltaic tracker is powered on, it will first load the firmware's built-in default parameters, read the stored data packets, and complete the CRC check. Only after the check is successful can the default parameters be replaced and the device put into operation.

[0025] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0026] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for heavy-load starting of a sensorless brushless motor for a photovoltaic tracker, characterized in that: Includes the following steps: Step S1: Receive motion commands from the photovoltaic tracker, parse them, and obtain the command type and target motion direction; synchronously collect the downtime of the brushless motor and the cumulative number of start-up failures. The command type corresponds to different operating conditions of the photovoltaic tracker. Step S2: Based on the instruction type, the downtime of the brushless motor, and the cumulative number of start-up failures of the brushless motor, match the heavy-load start-up parameter group of the brushless motor under the current operating conditions of the photovoltaic tracker. The heavy-load start-up parameter group includes pre-positioning parameters. Step S3: Based on the sensorless control mode, generate and execute the initial angle control command for the brushless motor; Step S4: Perform pre-positioning control of the brushless motor according to the pre-positioning parameters of the brushless motor; Step S5: Generate the open-loop electrical angle and open-loop frequency change slope of the brushless motor, and collect the bus voltage drop amplitude, phase current, estimated speed direction, estimated electrical angle and open-loop running time of the brushless motor in real time. Step S6: Determine whether the following conditions are met simultaneously: the bus voltage drop amplitude of the brushless motor is less than or equal to the preset drop amplitude limit; the phase current of the brushless motor is less than or equal to the preset phase current threshold; the estimated speed direction of the brushless motor is the same as the target motion direction; the deviation between the estimated electrical angle and the open-loop electrical angle of the brushless motor is less than the preset electrical angle error threshold; the slope of the open-loop frequency change of the brushless motor is within the preset slope range; and the open-loop running length is greater than or equal to the preset duration threshold. If yes, the brushless motor restart is considered successful, and the brushless motor closed-loop operation control is initiated. If no, the brushless motor restart is considered unsuccessful, and the heavy-load start parameter group is corrected according to the type of brushless motor restart failure before retrying the start, or a brushless motor fault alarm signal is generated.

2. The heavy-load start-up method for a sensorless brushless motor for a photovoltaic tracker according to claim 1, characterized in that: In step S2, the overload start-up parameter group also includes the open-loop frequency change slope, the closed-loop switching frequency window, the bus voltage drop limit, the number of allowed retry attempts, and the fault reporting type; the prepositioning parameters include the first prepositioning current, the second prepositioning current, and the prepositioning holding time.

3. The heavy-load start-up method for a sensorless brushless motor for a photovoltaic tracker according to claim 1, characterized in that: In step S3, the initial angle control command for the brushless motor specifically includes: Perform a reset and initialization operation on the position observer, speed loop, and current loop states of the brushless motor; The direction of the initial excitation magnetic field is given by using magnetic field alignment pre-positioning; The approximate sector of the brushless motor rotor is determined by comparing the current feedback response of each phase using the IPD pulse injection method. If residual speed is detected in the brushless motor, the direction of rotation of the brushless motor rotor is determined by combining the back EMF information and the operating status of the position observer, and it is verified whether the conditions for direct tracking start are met.

4. The heavy-load start-up method for a sensorless brushless motor for a photovoltaic tracker according to claim 2, characterized in that: Step S4 specifically includes the following sub-steps: Step S41: Apply the first prepositioning current and maintain the prepositioning holding time to pull and engage the rotor of the brushless motor along the target motion direction; Step S42: Use the second prepositioning current and maintain the prepositioning holding time to establish the starting torque.

5. A method for heavy-load starting of a sensorless brushless motor for a photovoltaic tracker according to claim 1, characterized in that: In step S6, when it is determined that the brushless motor restart has failed, the heavy-load start parameter group is modified according to the type of brushless motor restart failure, and the restart is retried. Specifically, this includes the following sub-steps: When the type of failure to restart the brushless motor is mechanical jamming, the power output of the brushless motor is stopped, and the preset positioning hold time is extended after a preset delay. When the type of brushless motor restart failure is overload, reduce the open-loop acceleration and increase the preposition hold time; When the type of failure to restart the brushless motor is insufficient power, reduce the starting current or terminate the retry restart process and wait for the power supply to be restored. When the type of brushless motor restart failure is open-loop start failure, the prepositioning control command is re-executed and the open-loop frequency change slope is reduced. When the type of brushless motor restart failure is closed-loop failure, the brushless motor will return to the stopped state, and the open-loop running time will be extended before retrying to start.

6. The heavy-load start-up method for a sensorless brushless motor for a photovoltaic tracker according to claim 1, characterized in that: It also includes the following steps: Establish a data storage repository; The matched heavy-load start parameter group, the cumulative number of start failures, and the types of brushless motor restart failures are all stored in the data storage library.

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