Photovoltaic tracking system based on solar time continuous driving and control method

Abstract

The invention discloses a photovoltaic tracking system based on solar time continuous driving and a control method. The system comprises a sun time calculation unit, an angle feedback unit, a control unit, a brushless motor driving unit and an execution mechanism. The sun time calculation unit is used for calculating the sun position, the angle feedback unit collects the posture of the photovoltaic support, and the control unit generates a control instruction according to deviation. The brushless motor driving unit adopts FOC and SVPWM algorithms under closed-loop control, so that the motor realizes ultra-low-speed continuous operation in a range of 0.1-10 rpm, and still keeps operation when the deviation is smaller than a threshold value, thereby avoiding angle dead zone and cosine loss caused by intermittent start and stop. The actuating mechanism is driven to adjust the posture of the photovoltaic support, so that the photovoltaic support continuously follows the sun around the clock. According to the scheme, the tracking precision and the energy utilization rate are improved, and the method is suitable for single-axis and double-axis photovoltaic tracking scenes.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaic power generation technology, and particularly relates to a photovoltaic tracking system based on continuous driving of solar time and a control method. BACKGROUND

[0002] The existing photovoltaic tracking system mostly adopts open-loop control or intermittent start-stop mode, that is, when there is a large deviation between the posture of the photovoltaic support and the azimuth of the sun, the motor is started to quickly adjust, and when the deviation is reduced to a certain threshold, the operation is stopped. Such mode has two deficiencies: one is that frequent start-stop causes mechanical impact and wear of the actuator, reducing the reliability and service life of the system; the other is that in the small angle deviation range, the normal line of the photovoltaic module and the sunlight cannot be accurately aligned, resulting in cosine loss, which reduces the overall power generation efficiency.

[0003] Especially in the high-precision tracking scene, how to make the motor still maintain smooth and continuous operation at extremely low speed, and avoid shaking and stagnation caused by static friction, cogging torque and other factors, has become a problem that the existing technology cannot solve. The existing scheme generally lacks effective control over the operation characteristics in the ultra-low speed range, and it is difficult to realize continuous and stable tracking in all weather conditions.

[0004] Therefore, the technical problem to be solved by the present application is to provide a photovoltaic tracking system and control method capable of maintaining continuous and smooth operation in the ultra-low speed range, so as to avoid the angle dead zone and cosine loss caused by the intermittent start-stop mode, and improve the tracking accuracy and energy utilization rate of the photovoltaic module. SUMMARY

[0005] In order to solve the problems of the prior art, the embodiments of the present application provide a photovoltaic tracking system based on continuous driving of solar time and a control method. The technical solution is as follows: On the one hand, a photovoltaic tracking system based on continuous driving of solar time is provided, comprising: A solar time calculation unit is configured to determine the spatial position parameters of the sun based on the latitude, longitude, date and time; An angle feedback unit is configured to obtain real-time posture information of the photovoltaic support; A control unit is connected with the solar time calculation unit and the angle feedback unit, and is configured to generate a driving control instruction according to the deviation between the solar position parameters and the real-time posture; A brushless motor driving unit is connected with the control unit, and is configured to drive the brushless motor to operate in a continuous manner at an ultra-low speed, and to maintain continuous operation when the deviation is less than a preset threshold, so as to avoid the cosine loss caused by the angle dead zone and the intermittent start-stop; An actuator is connected with the output shaft of the brushless motor driving unit, and is configured to adjust the posture of the photovoltaic support according to the continuous low-speed operation of the brushless motor; The angle feedback unit, the control unit, the brushless motor driving unit and the actuator constitute a closed-loop control loop, so that the attitude of the photovoltaic support continuously follows the change of the sun position in the whole-day operation and is stably adjusted.

[0006] Further, the sun time calculation unit comprises: A GPS module is configured to acquire longitude and latitude and coordinated universal time and transmit data to the control unit; A data processing module is configured to convert the longitude and latitude from degree-minute format to decimal degree format, and correct the local standard time to local solar time according to the longitude difference; when the GPS signal is invalid, the real-time clock module is called as a reference benchmark to maintain time update; when the GPS signal is restored, the real-time clock module is calibrated.

[0007] A sun position calculation module is configured to calculate the sun declination angle, the sun time difference, the sun hour angle, the sun elevation angle and the azimuth angle according to the longitude and latitude, the date and the time, and perform atmospheric refraction correction when the elevation angle is less than a preset threshold, and perform orbit eccentricity correction within the whole year to ensure that the comprehensive calculation error is not more than 0.05°.

[0008] Further, the angle feedback unit comprises: An inclination sensor has a resolution of not less than 0.01° and a repeatability error of not more than 0.05°, is installed at a rotating part of the photovoltaic support, and outputs a digital signal corresponding to the inclination angle through an I 2 A C interface communicates with the control unit and is configured to output a digital signal corresponding to the elevation angle; A Hall sensor is installed in the brushless motor and is configured to output a digital pulse signal corresponding to the rotor position; A fusion operation module is arranged in the control unit and is configured to perform weighted fusion on the data of the inclination sensor and the Hall sensor, and suppress noise and drift through a filtering algorithm, so as to form real-time attitude feedback for closed-loop control.

[0009] Further, the control unit comprises: A deviation calculation module is configured to compare the sun elevation angle and the azimuth angle output by the sun time calculation unit as target angles with the real-time attitude output by the angle feedback unit, so as to obtain the deviation values of the elevation angle and the azimuth angle; A PID adjustment module is configured to generate a correction control signal when the absolute value of the deviation value is greater than 0.05°, and maintain the brushless motor in continuous low-speed operation when the absolute value of the deviation value is less than or equal to 0.05°; A mode switching module is configured to automatically switch the operation mode according to the sun elevation angle and the illumination intensity in special working conditions such as night, cloudy day and noon, including night / cloudy day mode, noon zero-point calibration mode and seasonal adjustment mode.

[0010] Further, the brushless motor driving unit comprises: a microcontroller configured to run a field-oriented control (FOC) algorithm to achieve three-phase current decomposition and closed-loop regulation through Clarke / Park transformation; a space vector pulse width modulation (SVPWM) module for synthesizing a target voltage vector in an electrical angle range and generating three-phase PWM duty cycle signals; a current sampling circuit for real-time acquisition of three-phase currents and feedback to the microcontroller to achieve current loop closed-loop control; a dead-time compensation and over-modulation processing module for setting a dead-time in the PWM signal and compensating for the voltage error caused thereby, while performing clamping regulation when the voltage vector exceeds the hexagon boundary; wherein the brushless motor driving unit is configured to operate in continuous micro-step mode in a speed range of 0.1-10 rpm, and to maintain torque fluctuation of no more than 5% in the closed-loop control process, to achieve stable posture adjustment of the photovoltaic support at ultra-low speed.

[0011] In another aspect, a photovoltaic tracking control method based on continuous driving of solar time is provided, which is implemented by the photovoltaic tracking system and comprises: calculating the solar elevation angle and azimuth angle based on latitude, longitude, date and time; obtaining real-time posture information of the photovoltaic support; comparing the solar elevation angle and azimuth angle with the real-time posture to obtain an angle deviation; when the deviation is greater than a preset threshold, the control unit generates a driving control signal according to the deviation value; when the deviation is less than or equal to the threshold, the brushless motor is still kept continuously running at ultra-low speed to avoid cosine loss caused by angle dead zone and intermittent start-stop; driving the actuator to adjust the posture of the photovoltaic support according to the driving control signal, so that it continuously follows the change of the sun's position to perform stable tracking within the whole day.

[0012] Further, the calculation of the solar elevation angle and azimuth angle comprises: obtaining latitude, longitude and coordinated universal time (UTC) through a GPS module, and performing longitude correction; calling a real-time clock to maintain time update when short-time signal fails; calculating the solar declination angle, solar hour angle and solar time difference in combination with date and time, and performing atmospheric refraction correction when the elevation angle is less than a preset threshold, and performing orbit eccentricity correction within the whole year to ensure that the overall calculation error is not more than 0.05°.

[0013] Furthermore, the acquisition of the real-time attitude information includes: The elevation angle data of the photovoltaic support is obtained by using a tilt sensor with a resolution of not less than 0.01° and a repeatability error of not more than 0.05°. The rotor position pulse signal is obtained by a Hall sensor installed inside the brushless motor; The sensor data is fused and filtered in the control unit to suppress noise and drift, thereby forming real-time attitude feedback for closed-loop control.

[0014] Furthermore, the generation of the drive control signal includes: When the deviation is greater than 0.05°, the control unit uses a proportional-integral-derivative (PID) control algorithm to generate a correction control signal; When the deviation is less than or equal to 0.05°, the brushless motor drive unit maintains low-speed continuous operation.

[0015] Furthermore, the ultra-low speed continuous operation of the brushless motor is achieved through the following methods: The control unit performs Clarke and Park transformations on the acquired three-phase current signals to obtain the direct-axis and quadrature-axis currents, compares them with reference values, and generates voltage commands via a current regulator. The voltage commands are then transformed by an inverter to obtain three-phase voltage components, and a target voltage vector is synthesized using space vector pulse width modulation (SVPWM) to output a three-phase PWM duty cycle signal. The control unit performs closed-loop regulation of the current loop based on the real-time detection results of the current sampling circuit, and performs dead-zone compensation and overmodulation processing in the PWM signal to reduce voltage errors and torque fluctuations at low speeds. When the angle deviation is less than the threshold, the control unit outputs a constant low-speed speed command, enabling the brushless motor to operate continuously within the range of 0.1–10 rpm, and controlling torque fluctuations to no more than 5% during closed-loop control, thereby achieving stable attitude adjustment of the photovoltaic support at ultra-low speeds.

[0016] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows: This invention provides a photovoltaic tracking system and control method based on continuous solar time drive. The system obtains high-precision solar position parameters through a solar time calculation unit, combines them with real-time attitude information provided by an angle feedback unit, performs deviation calculation and closed-loop adjustment by a control unit, and achieves ultra-low-speed continuous operation by a brushless motor drive unit within the range of 0.1 to 10 rpm, thereby driving the actuator to perform stable and precise attitude adjustment of the photovoltaic support.

[0017] Through the above technical solution, this invention can maintain continuous motor operation even when the angle deviation is less than a preset threshold, effectively avoiding the angle dead zone and cosine loss caused by traditional intermittent start-stop methods. Under closed-loop control, the motor torque fluctuation is no more than 5%, and the bracket tracking error is stably controlled within ±0.05°, thereby significantly improving the accuracy and stability of photovoltaic tracking. At the same time, continuous low-speed operation reduces the mechanical shock and energy waste caused by frequent start-stop, extending the service life of the motor and actuator.

[0018] In summary, this invention achieves high-precision, all-weather photovoltaic tracking while also possessing comprehensive advantages such as high efficiency, low energy consumption, and long lifespan. It is suitable for single-axis and dual-axis photovoltaic tracking systems, and is particularly suitable for large-scale ground-mounted photovoltaic power plants with high requirements for operational continuity and energy utilization. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a photovoltaic tracking system based on continuous solar time drive according to Embodiment 1 of the present invention.

[0021] Figure 2 This is a flowchart of a photovoltaic tracking control method based on continuous solar time drive, which is an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0023] Example 1 This embodiment provides a photovoltaic tracking system based on continuous solar time drive. See [link to documentation]. Figure 1 It includes: a solar time calculation unit, an angle feedback unit, a control unit, a brushless motor drive unit, and an actuator. These units are interconnected via signal interfaces to form a closed-loop control circuit, used to adjust the photovoltaic support posture in real time as the sun's position changes.

[0024] In this closed-loop control circuit, the solar time calculation unit is used to determine the spatial position parameters of the sun based on latitude, longitude, date and time; the angle feedback unit is used to obtain the real-time attitude information of the photovoltaic support; the control unit generates drive control commands based on the deviation between the solar position parameters and the attitude feedback; the brushless motor drive unit receives the commands from the control unit and drives the actuator to achieve the attitude adjustment of the photovoltaic support.

[0025] Preferably, in the closed-loop control circuit, when the angle deviation |Δθ| is less than a preset threshold, the control unit does not stop the actuator, but maintains the brushless motor running continuously at an ultra-low speed. By outputting a non-zero minimum speed command within the threshold, the actuator maintains a slow and continuous movement, avoiding angle dead zones and cosine losses caused by intermittent start-stop, thereby ensuring that the photovoltaic support maintains stable and continuous tracking throughout the day.

[0026] Furthermore, the brushless motor drive unit can operate stably within a speed range of 0.1 to 10 rpm, and maintains torque peak-to-peak fluctuations of no more than 5% during closed-loop control to ensure the stability and repeatability of the photovoltaic support under ultra-low speed conditions.

[0027] Through the aforementioned structure and control strategy, this embodiment can maintain the photovoltaic support structure's continuous and stable tracking of the sun's position throughout the entire day's operation. Compared to the intermittent start-stop drive method in the prior art, this embodiment effectively avoids angle dead zones and transmission shocks caused by start-stop operations, and reduces cosine losses. Relying on the aforementioned continuous operation control and low-speed stability indicators, the photovoltaic support structure can achieve high-precision attitude adjustment throughout the day's operation, thereby significantly improving the tracking accuracy and energy utilization rate of photovoltaic modules, and is particularly suitable for the continuous and stable operation of large-scale ground-mounted photovoltaic power plants.

[0028] In this embodiment, the functional units cooperate to form a complete photovoltaic tracking control system: the solar time calculation unit outputs high-precision solar position parameters in real time; the angle feedback unit continuously monitors the actual attitude of the photovoltaic support; the control unit compares the target angle with the actual angle and generates continuous speed control commands; the brushless motor drive unit converts the control signal into a smooth motor drive current to drive the actuator to complete the angle adjustment of the support. The units maintain both real-time signal transmission and mechanical transmission stability, enabling the photovoltaic support to continuously track the sun's position during uninterrupted low-speed operation. The following will describe each functional unit of the system in detail.

[0029] 1. Solar Time Calculation Unit The hardware circuit of the solar time calculation unit uses an STM32F103RBT6 microcontroller. The solar time calculation unit is located inside the photovoltaic tracking controller and mainly includes a Global Positioning System (GPS) module, an atmospheric refraction correction module, and an Earth orbit eccentricity correction module.

[0030] The GPS module is used to collect real-time geographic and time information of the photovoltaic device's location. Its output parameters include latitude and longitude (accuracy better than 0.0001°), Coordinated Universal Time (UTC), positioning status, and date information. The module supports the NMEA-0183 standard communication protocol, outputting GPGGA (location information) and GPRMC (time and date information), and communicates with the control unit via a UART serial port. The module's startup performance is characterized by a cold start time of less than 30 seconds, a warm start time of less than 10 seconds, an operating current of no more than 50mA, and a standby current of no more than 10mA, making it suitable for low-power operation scenarios.

[0031] When the latitude and longitude data is output by the GPS module, it is in degrees and minutes format. The control unit calls the internal data conversion program to convert the latitude and longitude data. And longitude λ are respectively calculated according to the formula latitude: = Degrees + Minutes / 60 (North latitude is positive, South latitude is negative) Longitude: λ = degrees + minutes / 60 (East longitude is positive, West longitude is negative) Convert to decimal units to meet the input requirements of the subsequent solar position calculation algorithm.

[0032] The solar time calculation unit automatically performs longitude correction and time zone conversion based on the latitude and longitude and UTC time, combined with preset time zone data, to obtain the local standard time (LCT). Then, it calculates the local solar time (LST) to obtain a more accurate solar position reference. The local solar time calculation includes correction for the difference in central longitude and correction for the time difference. The time difference correction uses a Fourier series approximation formula to ensure that the error does not exceed 1 minute.

[0033] When the GPS signal fails, the control unit uses the real-time clock (RTC) as a time reference to continue calculating the solar altitude and azimuth angles and maintain the normal tracking operation of the photovoltaic support. Since the geographical location of the photovoltaic device is fixed, there is no need to consider coordinate displacement; the system can ensure the continuity of solar position calculation with the support of the RTC. When the GPS signal is restored, the system uses the received time data to calibrate the RTC to ensure long-term operational accuracy. Preferably, the real-time clock uses the DS1302 chip, which features low power consumption and high reliability, suitable for the continuous operation requirements of photovoltaic devices.

[0034] Atmospheric refraction correction module based on solar altitude angle The real-time calculation results, in When the angle is less than 5°, the correction formula is automatically invoked to compensate for the angular error caused by light refraction. The orbital eccentricity correction module makes a slight correction to the solar altitude angle based on the eccentricity of the Earth's orbit to reduce the cumulative positional deviation caused by the annual cycle. After the above processing, the combined calculation error of the solar altitude angle and azimuth angle output by the solar time calculation unit is no greater than 0.05°.

[0035] 2. Angle Feedback Unit The angle feedback unit includes two parts: a tilt sensor and a Hall sensor, which are used to acquire the elevation angle and azimuth angle information of the photovoltaic support, respectively, and output real-time attitude data through weighted calculation.

[0036] The tilt sensor is installed on the rotating part of the photovoltaic (PV) mounting bracket to measure the bracket's elevation angle relative to the horizontal plane. The sensor outputs an analog voltage signal, with a measurement resolution of at least 0.01° and a repeatability error of less than 0.05°, meeting the accuracy requirements for PV tracking. The sensor connects to I... 2 The C-bus interface communicates directly with the control unit. The control unit periodically reads the digital data output by the sensor and processes it in conjunction with filtering and calibration procedures to obtain stable and reliable elevation angle information. The Hall sensor is installed at the rotor position of the brushless motor and works with the multi-pole magnet built into the motor to generate pulse signals used to detect changes in the motor's rotor angle. The Hall sensor output is a digital pulse signal, and the number of pulses is proportional to the motor's rotation angle. In this embodiment, the Hall sensor resolution is arranged with three Hall sensors spaced at 120° electrical angle intervals, and higher angle detection accuracy is achieved through frequency multiplication processing by the MCU. The Hall signal is connected to the counter module of the control unit via a digital input port (GPIO), and the control unit records the motor rotation in real time.

[0037] The control unit collects data from the tilt sensor and the Hall sensor respectively, and performs fusion calculations according to preset weighting coefficients: Tilt sensor data serves as the primary reference for static attitude measurement, ensuring long-term accuracy. Hall sensor data serves as the primary reference for dynamic response and is used for detecting rapid changes in a short time.

[0038] The fused attitude data is filtered by a software algorithm to remove high-frequency interference and low-frequency drift, ultimately generating the elevation and azimuth angles of the support's real-time attitude. These angles are then compared with the target angles output by the solar time calculation unit, serving as direct inputs for the control unit to generate speed commands.

[0039] The design of this unit ensures that it can still output high-precision attitude data stably under complex environments such as wind load disturbance, temperature changes and electromagnetic interference, providing reliable feedback signals for closed-loop tracking control.

[0040] 3. Control Unit The control unit is located at the core of the photovoltaic tracking controller. It uses an STM32F103 series microcontroller as the main control chip, based on the ARM Cortex-M3 core. It possesses the processing power required for real-time angle calculation, closed-loop control, and multi-sensor data fusion. It integrates multiple general-purpose timers, PWM output channels, ADC input channels, and serial communication interfaces (UART, SPI, I / O). 2 (C) can efficiently complete solar position calculation, attitude deviation analysis, and drive command generation.

[0041] The control unit receives the target values ​​of solar altitude angle and azimuth angle sent by the solar time calculation unit via the UART interface, and then transmits them via I... 2 The C interface acquires the digital angle signal output from the tilt sensor, and the GPIO interrupt and counter module receives the pulse signal output from the Hall sensor. All input data undergoes filtering, calibration, and fusion calculations to form the real-time attitude data of the photovoltaic support.

[0042] During operation, the control unit refreshes the comparison between the attitude data and the target angle data every 100ms, calculating the deviation value Δθ. When |Δθ| is greater than 0.05°, the control unit immediately enters the adjustment state, generating a continuous speed command signal based on the direction and magnitude of the deviation, which is sent to the PWM generation module to drive the brushless motor. When |Δθ| is less than or equal to 0.05°, the control unit maintains the brushless motor in a low-speed synchronous operation state to avoid mechanical shock and increased energy consumption caused by frequent start-stop operations.

[0043] The control unit has a built-in proportional-integral-derivative (PID) controller. The proportional term (P) is used to speed up the system response. The integral term (I) is used to eliminate steady-state errors and ensure accurate attitude alignment; The differential term (D) is used to suppress overshoot during rapid changes.

[0044] In addition, the control unit has special operating mode logic: 1) Night / Cloudy Mode: When the sun's altitude angle < 5° or light intensity below 200W / m 2 When detected by a light sensor, a reset command is output, causing the actuator to adjust the bracket to a horizontal position or a preset windproof angle.

[0045] 2) Noon Correction Mode: When the local solar time LST = 12, the theoretical azimuth angle 0° (due south) is used as the calibration reference to calibrate the zero-point drift of the azimuth angle measurement.

[0046] 3) Seasonal adjustment mode: The tracking calculation and execution frequency is automatically adjusted according to seasonal changes. When the altitude angle is low in winter, the tracking control is updated once every 30 seconds. In summer, the frequency can be relaxed to once every 120 seconds to reduce the number of motor actions and extend the mechanical life.

[0047] The control unit outputs speed control commands to the brushless motor drive unit through three PWM signal lines, and receives motor operating current data in real time through the current sampling feedback line. This data is used for FOC current loop closed-loop control and overcurrent protection triggering, achieving high-precision, low-latency attitude control.

[0048] 4. Brushless motor drive unit The brushless motor drive unit employs field-oriented control (FOC) technology to drive a three-phase brushless DC motor with four pairs of magnetic poles, achieving continuous low-speed operation from 0.1 to 10 rpm. This unit mainly consists of a microcontroller, a three-phase gate driver chip, power MOSFETs, current sampling resistors, and related protection circuits.

[0049] (1) Microcontroller The microcontroller selected is the STM32F103 series, which internally runs the FOC algorithm and the Space Vector Pulse Width Modulation (SVPWM) algorithm, and has the processing performance to achieve real-time control and accurate calculation under low-speed conditions. Three complementary PWM signals are generated through the internal timer module to drive the three-phase full-bridge inverter, while the three-phase current signals are collected for closed-loop regulation.

[0050] (2) Gate driver chip The driver chip selected is the EG2133, which has three high-end and low-end half-bridge drive capabilities (HO / LO) and supports a maximum PWM input frequency of 500kHz. This chip integrates a typical 300~500ns dead-time control circuit and interlock protection function to prevent shoot-through between the upper and lower bridge arms and improve system reliability; it also supports 3.3V / 5V logic level input and can be directly connected to an STM32 microcontroller.

[0051] (3) Power MOSFET The power device selected is the NCE6080XAG N-channel MOSFET, whose main characteristics include: On-resistance RDS(ON) < 8.5mΩ (VGS=10V), reducing conduction losses; Withstand voltage VDS = 60V, compatible with 12V~48V motor systems; Continuous drain current ID = 80A (25℃), pulse current up to 320A; The package has a thermal resistance of 1.36℃ / W, supporting continuous high-current operation; It passes a 100% avalanche energy test to ensure stable operation under back EMF impact.

[0052] (4) Current sampling and protection A high-precision sampling resistor (accuracy ±1%) is connected in series in the three-phase motor winding circuit to collect the phase current signal and input it to the MCU's ADC channel. This signal is used for Clarke / Park conversion to calculate the torque and excitation components, and to implement a control strategy of Id≈0 to reduce copper and iron losses. When the detected current peak exceeds the set threshold, the control circuit immediately triggers hardware shutdown to prevent the MOSFET from being damaged due to overcurrent and overheating.

[0053] (5) Control algorithm and operation mode The FOC (Field Oriented Control) process of the drive unit includes the following steps: 1) Rotor position detection This embodiment uses a Hall sensor installed at the end of the motor to obtain the rotor mechanical angle. (Unit: ° or rad), and normalized (remainder 360° or 2π) to ensure continuous and stable angle data within the calculation cycle. The sampling frequency should be no less than twice the PWM frequency to ensure the real-time performance and accuracy of subsequent electrical angle calculations. In other implementations, an encoder mounted on the motor shaft can also be used to implement the angle detection function to meet different accuracy and cost requirements.

[0054] 2) Electrical Angle Calculation Based on the number of pole pairs of the motor , mechanical angle Converted to electrical angle (Unit: ° or rad), the formula is: Taking 4 pairs of magnetic poles as an example ( = 4), when the rotor rotates one mechanical angle (360°), the electrical angle changes by 1440° (4 electrical cycles). Electrical angle It is then mapped to the interval [0, 360°) to accommodate the periodic requirements of SVPWM operations.

[0055] 3) Sector identification and vector decomposition According to the electric angle Determine which of the six sectors of the SVPWM currently in operation (each sector is 60° electrical angle), and combine the current sample value with the target voltage vector. (Unit: V), Calculate: : The duration of action of the basic voltage vector in the clockwise direction (unit: s); : Duration of the basic voltage vector in the counterclockwise direction (unit: s); Zero voltage vector action time (unit: s), by It is concluded that, among them The PWM period (unit: seconds).

[0056] The DC bus voltage must be considered during the calculation. To mitigate fluctuations and avoid duty cycle saturation.

[0057] 4) Three-phase PWM generation Convert the operating time into the duty cycle of the three-phase bridge arm. (Dimensionless, 0~1), the formula is: in and These represent the switching states of the m-th and n-th basic voltage vectors in phase x (1 indicates on, 0 indicates off). The duty cycle signal generates a complementary PWM waveform through an internal timer and outputs it to the gate signal input of the driver chip; a dead time should be added between the complementary signals (to prevent shoot-through between the upper and lower bridge arms).

[0058] 5) Dead zone compensation Dead time causes deviations in the amplitude and phase of the voltage vector, which is particularly noticeable at low speeds. By using software compensation and introducing a correction in the duty cycle calculation, the phase voltage waveform is made consistent with the theoretical value, thereby improving torque stability during low-speed operation.

[0059] 6) Overmodulation processing When the target voltage vector exceeds the SVPWM hexagonal modulation range, it is reduced proportionally. and This ensures that the vector endpoints fall within the modulated range, preventing waveform distortion and harmonic increase.

[0060] Through the synergy of the aforementioned hardware and algorithms, the torque fluctuation of the drive unit in this embodiment is controlled within 5% under low-speed (0.1 rpm) conditions, and the peak current at startup is kept within a safe multiple of the rated current, effectively reducing mechanical shock and energy consumption, and improving the stability and lifespan of the system operation.

[0061] Preferably, to achieve ultra-low speed continuous operation, the control unit performs Clarke and Park transformations during closed-loop control, decomposing the acquired three-phase current into direct-axis current Id and quadrature-axis current Iq, and comparing them with reference values. After generating voltage commands through the current regulator, the voltage is restored to three-phase voltage components through inverter coordinate transformation, and finally, the target voltage vector is synthesized by the space vector pulse width modulation (SVPWM) module, thereby realizing the generation and output of the three-phase PWM duty cycle signal.

[0062] To ensure smooth operation at low speeds, the system employs a high-precision shunt resistor and a low-noise amplifier circuit in the current sampling circuit to suppress quantization errors during small current measurements. A dead-time compensation and overmodulation processing mechanism is set at the PWM signal generation end to correct voltage deviations caused by dead time and to perform clamping adjustment when the voltage vector exceeds the hexagonal boundary to avoid motor jitter.

[0063] Furthermore, the speed loop maintains a given minimum continuous speed command within a threshold range (e.g., 0.1–10 rpm), and the current loop bandwidth is preferably configured to be an order of magnitude higher than that of the speed loop to ensure rapid recovery of balance under disturbance conditions. Through the synergy of the above control and hardware measures, the motor can maintain torque fluctuations of no more than 5% in the low-speed operating range, effectively overcoming the jitter caused by static friction and cogging torque, thereby ensuring the smoothness and repeatability of the photovoltaic support posture adjustment process.

[0064] 5. Implementing agency The actuator is the attitude adjustment mechanism of the photovoltaic bracket, which is used to drive the photovoltaic panel to perform single-axis or dual-axis tracking adjustment according to the speed and direction commands issued by the control unit, so as to ensure that the normal direction of the photovoltaic panel is consistent with the direction of sunlight.

[0065] (1) Mechanical connection structure The actuator is connected to the output shaft of the brushless motor drive unit via a reducer. The reducer uses a high-precision helical gear or worm gear structure to amplify the output torque and improve motion smoothness. The reduction ratio is determined based on the bracket size and load characteristics; for example, a high reduction ratio structure of ≥1:100 is used in large photovoltaic arrays to reduce motor load fluctuations. The output end of the brushless motor is connected to the input shaft of the reducer via a coupling. The coupling uses a rigid or elastic structure to balance transmission accuracy and impact resistance. The output end of the reducer is fixedly connected to the rotating hinge point of the bracket via a flange or shaft pin, thereby achieving attitude adjustment.

[0066] (2) Single-axis execution mode Single-axis mode adjusts only one degree of freedom, typically azimuth adjustment (horizontal single-axis) or elevation adjustment (tilt single-axis). It has a simple structure and low cost. The single-axis mechanism converts the rotational motion output by the motor into the linear push-pull motion of the support through lead screw drive or rack and pinion drive, thereby achieving angle change.

[0067] (3) Dual-axis execution mode The dual-axis mode is adjustable in both azimuth and elevation angles, making it suitable for photovoltaic systems requiring high-efficiency tracking. In the dual-axis structure, one axis (the main axis) is mounted on the base for horizontal rotation, while the other axis (the secondary axis) is mounted on the main axis for elevation angle adjustment. The two axes are each controlled by an independent brushless motor drive unit, or, in low-power scenarios, they can share a single drive control system, achieving bidirectional adjustment through a mechanical distribution mechanism.

[0068] (4) Matching of transmission and precision The transmission system of the actuator must match the control precision of the brushless motor drive unit. Using tilt sensors and Hall effect sensors as attitude feedback sources, the control unit calibrates the minimum pulse movement of the motor against the angle adjustment precision of the support, ensuring that the angle change of the support corresponding to a single pulse does not exceed 0.01°. For lead screw drive structures, the lead screw lead and reduction ratio jointly determine the proportional relationship between the output displacement and the motor rotation angle; for gear transmission structures, the gear module, gear ratio, and number of transmission stages jointly affect the angle accuracy and transmission efficiency.

[0069] (5) Mechanical limit and protection The actuator is equipped with mechanical limit devices and soft limit logic to prevent the support structure from exceeding the safe angle range under extreme operating conditions. Mechanical limit is achieved through hardware stops, while soft limit is determined by the control unit based on angle feedback signals. In extreme weather conditions such as strong winds and heavy rain, the actuator can quickly adjust the photovoltaic support structure to a windproof or protective position to reduce stress and damage risks.

[0070] (6) Coordination with the drive unit The motion response of the actuator is powered and controlled by a brushless motor drive unit. The PWM signal output from the control unit is amplified into a three-phase AC current by the drive unit, driving the motor to output a continuous and stable torque, which is then used to smoothly adjust the bracket through the reducer output shaft. The torque fluctuation during low-speed operation is less than 5%, avoiding the problems of vibration and positioning overshoot of the photovoltaic bracket during adjustment.

[0071] In summary, the photovoltaic tracking system based on continuous solar time drive provided in this embodiment achieves high-precision real-time calculation of the sun's position through a solar time calculation unit. Combined with attitude measurement data provided by an angle feedback unit, the control unit performs deviation analysis and generates continuous low-speed operation commands. A brushless motor drive unit uses FOC and SVPWM algorithms to stably drive the actuator within an ultra-low speed range, thereby achieving smooth and precise adjustment of the photovoltaic support. The system maintains torque fluctuations of no more than 5% within the low-speed operating range of 0.1–10 rpm, effectively eliminating angle threshold dead zones and cosine losses and mechanical shocks caused by frequent start-stop cycles. Furthermore, in addition to possessing all-weather high-precision tracking capabilities, the system can also achieve equipment protection through mode switching under nighttime, cloudy, and extreme weather conditions. It boasts comprehensive technical advantages such as high tracking efficiency, low energy consumption, good operational stability, and long service life, making it suitable for various photovoltaic tracking application scenarios, including single-axis and dual-axis systems.

[0072] Example 2 like Figure 2 As shown, the present invention proposes a photovoltaic tracking control method based on continuous solar time drive, comprising the following steps: First, obtain latitude, longitude and time parameters, and calculate the solar altitude angle and azimuth angle accordingly; then, collect the real-time attitude information of the photovoltaic support, compare the target angle with the actual attitude to obtain the deviation value, and generate a continuous low-speed operation control command based on the deviation analysis; the command is executed by the brushless motor drive unit, so that the motor runs stably in ultra-low speed mode, thereby driving the actuator to smoothly adjust the photovoltaic support.

[0073] During operation, the method further automatically determines whether to enter night / cloudy mode based on the solar altitude angle and light intensity, performs noon zero-point calibration according to the local solar time, and adjusts the tracking frequency in combination with seasonal patterns to ensure that the system has stable and reliable tracking performance in all weather conditions and throughout the year.

[0074] The method in this embodiment mainly includes six steps: position and time data acquisition, solar position calculation, bracket attitude acquisition, continuous low-speed control command generation, brushless motor drive execution, and special operating mode control. These steps form a closed loop through data interaction and control logic: the solar time calculation unit outputs a high-precision target angle, the angle feedback unit provides real-time attitude information, the control unit performs deviation analysis and mode switching based on the comparison of the two, the drive unit converts the control commands into motor power output, and the actuator adjusts the photovoltaic bracket angle accordingly, thereby achieving continuous alignment between the photovoltaic panel's normal direction and the direction of sunlight. The following will provide a detailed explanation of each step.

[0075] Step 1: Obtain geographical location and time parameters In this step, the geographical location information and time parameters of the photovoltaic device are obtained in real time by the Global Positioning System (GPS) module installed in the solar time calculation unit.

[0076] The GPS module, model G030, has the following performance specifications: Output parameters include latitude and longitude (accuracy better than 0.0001°), Coordinated Universal Time (UTC), positioning status, and date information; Communication protocol: Compliant with NMEA-0183 standard, supporting GPGGA (location information) and GPRMC (time and date information) statements; Startup performance: Cold start time less than 30 seconds, warm start time less than 10 seconds; Power consumption: Operating current not exceeding 50mA, standby current not exceeding 10mA, suitable for low-power operation scenarios.

[0077] The GPS module communicates with the control unit via a UART interface. Upon receiving the GPGGA and GPRMC commands, the control unit first parses the latitude and longitude data in degree format and converts it to decimal units using the following formulas: latitude: = Degrees + Minutes / 60 (North latitude is positive, South latitude is negative) Longitude: λ = degrees + minutes / 60 (East longitude is positive, West longitude is negative) After the conversion is completed, the control unit automatically determines and corrects the time zone based on the longitude difference to obtain the local standard time (LCT). Then, based on this, longitude correction is performed to finally obtain the local solar time (LST) used for calculating the sun's position.

[0078] To ensure system continuity in the event of signal interruption, the method incorporates a fault-tolerant mechanism: When the GPS signal fails briefly (less than 5 minutes), the real-time clock (RTC) is invoked to maintain time updates and the sun's position is calculated using fixed geographic location parameters. When the GPS signal fails for an extended period (more than 5 minutes), the system maintains the current support posture and pauses tracking adjustments to avoid the accumulation of tracking errors caused by inaccurate location data.

[0079] The output of this step is the decimal values ​​of latitude and longitude, local solar time, and date information. These data will serve as the basic input for calculating the solar altitude angle and azimuth angle in step two.

[0080] Step 2: Calculate the real-time solar altitude angle and azimuth angle. In this step, the control unit calculates the real-time solar altitude angle based on the local solar time (LST), latitude and longitude, and date information obtained in step one, combined with the solar motion astronomical model. ) and azimuth (A).

[0081] First, calculate the solar declination angle δ (unit: degrees) based on the date. The solar declination angle is the angle between the sun's rays and the Earth's equatorial plane, ranging from -23.45° to +23.45°, and varies with the date. The formula is: Where N is the date of the year (N=1 for January 1, N=365 or 366 for December 31).

[0082] Then, the solar time difference E (in minutes) is calculated. This value is used to correct for the difference between true solar time and mean solar time, using an approximate Fourier series formula: in, The unit of B is degrees, which need to be converted to radians for trigonometric operations.

[0083] Next, calculate the solar time angle H (unit: degrees) based on the local solar time: The value of H ranges from -180° to +180°, with negative values ​​indicating morning (east) and positive values ​​indicating afternoon (west).

[0084] Combining latitude Solar declination angle and solar hour angle Calculate the solar altitude angle using spherical trigonometry formulas : Calculated The range is from 0° to 90°. A negative result indicates that the sun is below the horizon.

[0085] The formula for calculating the solar azimuth angle A is: The calculation result A ranges from -180° to +180°. Negative values ​​indicate eastward deviation, and positive values ​​indicate westward deviation. It can be converted to a form from 0° to 360° as needed.

[0086] After the calculation is complete, the method performs two types of corrections on the results: 1. Atmospheric refraction correction: when the elevation angle When the angle is less than 5°, the refraction correction formula is applied to... Compensation is performed to reduce observation errors caused by light refraction at low elevation angles; 2. Orbital eccentricity correction: Based on the elliptical nature of Earth's orbit, the eccentricity is corrected... Make minor adjustments to reduce the cumulative positional deviation caused by the annual cycle.

[0087] After the above calculations and corrections, the combined calculation error of the output solar altitude angle and azimuth angle does not exceed 0.05°, and is used as the target attitude input for subsequent steps.

[0088] Step 3: Obtain the actual posture of the photovoltaic support In this step, the angle feedback unit simultaneously collects the output data from the tilt sensor and the Hall sensor, and performs fusion calculations through the control unit to obtain the real-time attitude information of the photovoltaic support, including the elevation angle and azimuth angle.

[0089] 1. Tilt sensor measurement The tilt sensor is mounted on the rotating structure of the photovoltaic support. Its output is a digital angle signal corresponding to the elevation angle, with a measurement resolution of no less than 0.01° and a repeatability error of no more than 0.05°, meeting the requirements for high-precision photovoltaic tracking. The sensor connects via I... 2 The C-bus interface communicates directly with the control unit. The control unit periodically reads the digital data from the sensor and processes it in conjunction with filtering and calibration algorithms to obtain stable and reliable elevation angle information.

[0090] 2. Hall sensor measurement Hall effect sensors are installed inside the brushless motor, working in conjunction with magnets on the motor rotor. Rotation generates pulse signals, each pulse corresponding to a specific electrical angle change. In this embodiment, three Hall effect sensors are arranged at 120° electrical angle intervals, and the signals are frequency-multiplied within the control unit to improve angular resolution. The Hall effect signals are connected to the high-speed digital input (GPIO) of the control unit, where a timer counting module records the number of pulses in real time. This count, combined with the motor reduction ratio and lead screw lead, is then used to calculate the angle change of the support.

[0091] 3. Data fusion and attitude output After acquiring data from the tilt sensor and the Hall sensor, the control unit performs weighted fusion according to preset weighting coefficients: Tilt sensor data serves as the primary reference source for static attitude, ensuring long-term accuracy. Hall sensor data serves as the primary reference source for dynamic changes, enabling rapid response and minute angle adjustments.

[0092] The fused attitude data is denoised and drift corrected using a Kalman filter algorithm or a weighted average filter algorithm, ultimately generating the real-time elevation and azimuth angles of the support, which are then input into the deviation calculation program of the control unit in digital form.

[0093] 4. Output accuracy and stability Under typical operating conditions, the measurement error of the fused attitude data is no greater than ±0.02°, and the signal update cycle is no more than 100ms, which can meet the requirements of continuous tracking control for real-time performance and stability.

[0094] The output of this step is high-precision real-time attitude data of the support structure, which will be compared with the solar target angle obtained in step two and used as the input basis for generating continuous speed control commands in step four.

[0095] Step 4: Generate continuous speed control commands In this step, the control unit compares the solar target angle obtained in step two with the actual attitude of the photovoltaic support obtained in step three, calculates the angle deviation value Δθ, and generates a continuous speed control command based on the deviation value to drive the brushless motor to operate at low speed and in a stable manner.

[0096] 1. Deviation Calculation The control unit calculates the elevation angle deviation separately. and azimuth deviation : When the system is single-axis tracking, only the deviation value of the corresponding degree of freedom is calculated; when it is dual-axis tracking, the deviations of the two degrees of freedom are calculated separately and controlled independently.

[0097] 2. Threshold Determination and Control Mode Selection When |Δθ| ≤ 0.05° (where Δθ represents the deviation value of the current control axis), the control unit maintains the low-speed synchronous operation of the brushless motor to ensure continuous tracking without start-stop shock. When |Δθ| > 0.05°, it enters the deviation correction mode, accelerating the adjustment to bring the bracket closer to the target angle as quickly as possible. Preferably, the speed range of the low-speed synchronous motor is 0.1 to 10 rpm, and the torque fluctuation is kept no greater than 5% during closed-loop control, thereby achieving stable attitude adjustment of the photovoltaic bracket at ultra-low speeds.

[0098] 3. PID controller The control unit has a built-in proportional-integral-derivative (PID) controller that calculates the target motor speed command in real time based on the deviation value. Proportional term (P): Accelerates response speed, enabling the support to quickly approach the target angle; Integral term (I): Eliminates steady-state error and prevents small angular deviations that persist for a long time; Differential term (D): Suppresses overshoot and oscillation during rapid changes, improving system stability.

[0099] The PID output is the target speed value v, which is converted into the corresponding motor control pulse frequency based on the motor's reduction ratio and transmission structure.

[0100] 4. Speed ​​control quantity generation The control unit converts the target speed v into a duty cycle control quantity of a three-phase PWM signal. The signal is output to the brushless motor drive unit via a digital signal interface as input parameters for the FOC and SVPWM algorithms, thereby achieving precise low-speed torque control.

[0101] 5. Update cycle and real-time performance The update cycle for deviation calculation and speed control command generation does not exceed 100ms, ensuring that tracking accuracy and control stability can be maintained even under rapidly changing lighting conditions and rapidly changing sun positions.

[0102] Through the above processing, the continuous speed control command output in this step will directly enter the low-speed motor drive execution process in step five, realizing the smooth adjustment of the photovoltaic support posture.

[0103] Step 5: Low-speed continuous drive of photovoltaic bracket In this step, the brushless motor drive unit runs the field-oriented control (FOC) and space vector pulse width modulation (SVPWM) algorithms according to the continuous speed control command generated in step four, driving a three-phase brushless DC motor with four pairs of magnetic poles to achieve low-speed and stable operation in the range of 0.1~10rpm, thereby driving the actuator to adjust the attitude of the photovoltaic bracket.

[0104] 1. Rotor position detection and electrical angle calculation The drive unit first obtains the mechanical angle θm of the motor rotor through a Hall sensor, and then calculates the electrical angle θe based on the characteristics of the four pairs of magnetic poles: in The electrical angle is used for SVPWM calculation. This refers to the mechanical angle, used for monitoring the mechanical posture.

[0105] 2. Current Sampling and Coordinate Transformation The three-phase winding current is detected in real time using high-precision sampling resistors, with a sampling accuracy of no less than ±1%. The drive unit converts the three-phase current ( , , After Clarke transformation, it is converted into a two-phase stationary coordinate system current. , Then, the torque component current is obtained through Park transformation. With excitation component current .

[0106] 3. Current loop and speed loop control Current loop control: With id≈0 as the target, the excitation current is minimized to reduce copper and iron losses; the output torque is controlled by iq and compared with the target value; the PWM duty cycle is adjusted by a PI regulator. Speed ​​loop control: Using the target speed generated in step four as a reference, output the target value of iq. The speed loop refresh cycle does not exceed 1ms to ensure the response sensitivity under low-speed conditions.

[0107] 4. SVPWM Calculation and Sector Determination Determine the SVPWM sector (interval 1~6, 60° electrical angle per interval) based on the current electrical angle θe, and calculate the basic voltage vector action time Tm, Tn and zero vector time T0: in This is the DC bus voltage. The target voltage vector magnitude, For PWM period, This is the current sector number.

[0108] 5. Dead zone compensation and overmodulation processing Dead time compensation: To avoid shoot-through between upper and lower bridge arms, the hardware automatically adds a dead time of 300~500ns, and the software compensates for the voltage loss caused by the dead time. Overmodulation processing: when + > Scaling by proportion and This prevents the voltage vector from exceeding the hexagonal modulation range.

[0109] 6. Low-speed operation stability The drive unit improves the rotor position detection accuracy at an extremely low speed of 0.1 rpm by using a high-frequency signal injection method, making the torque fluctuation less than 5% and ensuring a smooth and vibration-free bracket adjustment process.

[0110] 7. Power Transmission and Execution The power of the brushless motor is transmitted to the actuator via a reducer and coupling, driving the photovoltaic bracket to perform single-axis or dual-axis attitude adjustments. During the adjustment process, the system maintains real-time closed-loop control until the deviation value is less than 0.05°.

[0111] After this step is completed, the orientation of the photovoltaic support will be highly consistent with the solar position parameters calculated in step two, ensuring that the photovoltaic panel is at the optimal angle for receiving sunlight.

[0112] Step Six: Execute Special Operating Mode In this step, the control unit determines whether it is necessary to switch to a special operating mode based on the solar altitude angle output by the solar time calculation unit, the attitude information provided by the angle feedback unit, and the real-time light intensity data output by the light sensor, in order to adapt to abnormal operating conditions such as nighttime, cloudy days, and extreme weather, thereby ensuring system safety and structural lifespan.

[0113] 1. Night / Cloudy Mode Triggering conditions: When the solar altitude angle < 5°; or Illumination intensity below 200W / m 2 (Detected by a light sensor).

[0114] Execution process: The control unit immediately stops tracking operation, generates a reset command, and sets the target position of the brushless motor drive unit to a horizontal posture or a preset windproof angle. During normal tracking, the drive unit performs low-speed positioning to avoid mechanical impact caused by rapid movements. When the control unit receives a strong wind alarm signal, the drive unit quickly adjusts the photovoltaic bracket to the preset windproof angle, thereby improving the system's safety in extreme weather conditions.

[0115] After the reset is complete, the system enters a low-power standby state, maintaining only the time update and environmental monitoring functions of the solar time calculation unit.

[0116] Recovery logic: When the solar altitude angle is greater than 5° and the light intensity is higher than 200W / m² 2 When the system automatically exits night / cloudy mode, it resumes normal tracking operation.

[0117] 2. Noon Correction Mode Triggering conditions: When the local solar time LST = 12, the sun is theoretically due south, and the azimuth angle should be 0° (or 180°, depending on the local coordinate system definition).

[0118] Execution process: The system pauses tracking operation and reads the azimuth data from the angle feedback unit; Compare this data with the theoretical value to calculate the zero-point offset; Update the calibration coefficients for azimuth measurement to eliminate sensor zero-point drift errors caused by long-term operation.

[0119] Recovery logic: After calibration, the system immediately resumed tracking operation, and the deviation calculation and speed control algorithm continued to execute according to the updated calibration coefficients.

[0120] 3. Seasonal Adjustment Pattern Triggering conditions: The system detects changes in the average daily solar altitude angle caused by seasonal variations, or automatically switches operating strategies via a preset calendar.

[0121] Execution process: In winter, due to the lower solar altitude angle and shorter sunshine hours, the tracking calculation and execution frequency is increased to once every 10 seconds to maintain high accuracy; In summer, due to the higher solar altitude angle and longer daylight hours, the frequency is reduced to once every 30 seconds.

[0122] Recovery logic: Seasonal adjustments are automatically switched according to a preset schedule, or the strategy can be manually adjusted by the operator through the control system.

[0123] In summary, the photovoltaic tracking method based on continuous solar time drive provided in this embodiment achieves all-weather, continuous, high-precision tracking of the photovoltaic support through high-precision position and time analysis by the solar time calculation unit, real-time attitude acquisition by the angle feedback unit, deviation analysis and PID adjustment by the control unit, FOC and SVPWM low-speed control by the brushless motor drive unit, and smooth attitude adjustment by the actuator. This method effectively eliminates the angle dead zone and frequent start-stop problems inherent in traditional threshold-triggered tracking, reduces cosine losses, improves photoelectric conversion efficiency, and significantly reduces motor start-up impact and energy consumption. Furthermore, the method can ensure system safety and extend the service life of mechanical structures by automatically switching operating modes under special conditions such as nighttime, cloudy days, and seasonal changes, making it suitable for the operation and control scenarios of various single-axis and dual-axis photovoltaic tracking systems.

[0124] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A photovoltaic tracking system based on continuous solar time driving, characterized in that, include: The solar time calculation unit is used to determine the spatial position parameters of the sun based on latitude, longitude, date, and time. Angle feedback unit is used to obtain real-time attitude information of the photovoltaic support; The control unit, connected to the solar time calculation unit and the angle feedback unit, is used to generate drive control commands based on the deviation between the solar position parameters and the real-time attitude. A brushless motor drive unit, connected to the control unit, is used to drive the brushless motor to operate continuously at ultra-low speeds and maintain continuous operation when the deviation is less than a preset threshold, so as to avoid cosine loss caused by angle dead zone and intermittent start and stop. An actuator, connected to the output shaft of the brushless motor drive unit, is used to adjust the posture of the photovoltaic bracket according to the continuous low-speed operation of the brushless motor. The angle feedback unit, control unit, brushless motor drive unit, and actuator form a closed-loop control circuit to ensure that the attitude of the photovoltaic support is continuously and stably adjusted to follow the changes in the sun's position throughout the day.

2. The photovoltaic tracking system based on continuous solar time drive according to claim 1, characterized in that, The solar time calculation unit includes: The GPS module is used to obtain latitude, longitude, and UTC, and transmit the data to the control unit; The data processing module is used to convert latitude and longitude from degrees to decimal units and correct the local standard time to local solar time based on the longitude difference; when the GPS signal fails, it calls the real-time clock module as a reference to maintain time updates; when the GPS signal is restored, it calibrates the real-time clock module. The solar position calculation module is used to calculate the solar declination angle, solar time difference, solar hour angle, solar altitude angle and azimuth angle based on latitude, longitude, date and time. It performs atmospheric refraction correction when the altitude angle is less than a preset threshold and performs orbital eccentricity correction throughout the year to ensure that the overall calculation error does not exceed 0.05°.

3. The photovoltaic tracking system based on continuous solar time drive according to claim 2, characterized in that, The angle feedback unit includes: A tilt sensor, with a resolution of no less than 0.01° and a repeatability error of no more than 0.05°, is installed on the rotating part of the photovoltaic support and connected via I... 2 The C interface communicates with the control unit and is used to output a digital signal corresponding to the elevation angle. Hall effect sensors, installed inside the brushless motor, are used to output digital pulse signals corresponding to the rotor position; The fusion computing module, located in the control unit, is used to perform weighted fusion of the tilt sensor and Hall sensor data, and to suppress noise and drift through a filtering algorithm, thereby forming real-time attitude feedback for closed-loop control.

4. The photovoltaic tracking system based on continuous solar time drive according to claim 3, characterized in that, The control unit includes: The deviation calculation module is used to compare the solar altitude angle and azimuth angle output by the solar time calculation unit as the target angle with the real-time attitude output by the angle feedback unit to obtain the deviation values ​​of the altitude angle and azimuth angle. The PID control module generates a correction control signal when the absolute value of the deviation is greater than 0.05°, and maintains the brushless motor running at low speed continuously when the absolute value of the deviation is less than or equal to 0.05°. The mode switching module is used to automatically switch the operating mode according to the solar altitude angle and light intensity under special working conditions such as night, cloudy days and noon. It includes night / cloudy mode, noon zero-point calibration mode and seasonal adjustment mode.

5. The photovoltaic tracking system based on continuous solar time drive according to claim 4, characterized in that, The brushless motor drive unit includes: The microcontroller is configured to run a field-oriented control algorithm, which uses Clarke / Park transformation to achieve three-phase current decomposition and closed-loop regulation. The space vector pulse width modulation module is used to synthesize the target voltage vector within the electrical angle range and generate a three-phase PWM duty cycle signal; A current sampling circuit is used to collect three-phase current in real time and feed it back to the microcontroller to realize closed-loop control of the current loop; The dead-time compensation and overmodulation processing module is used to set the dead time in the PWM signal and compensate for the voltage error caused thereby, while performing clamping adjustment when the voltage vector exceeds the hexagonal boundary; The brushless motor drive unit is configured to operate in a continuous micro-step manner within a speed range of 0.1 to 10 rpm, and to maintain torque fluctuation of no more than 5% during closed-loop control, so as to achieve stable posture adjustment of the photovoltaic bracket at ultra-low speed.

6. A photovoltaic tracking control method based on continuous solar time drive, characterized in that, The method is implemented by the photovoltaic tracking system according to any one of claims 1 to 5, comprising: Calculate the solar altitude angle and azimuth angle based on latitude, longitude, date, and time; Obtain real-time attitude information of the photovoltaic support structure; The solar altitude angle and azimuth angle are compared with the real-time attitude to obtain the angle deviation; When the deviation is greater than a preset threshold, the control unit generates a drive control signal based on the deviation value; When the deviation is less than or equal to the threshold, the brushless motor continues to operate at ultra-low speed to avoid cosine loss caused by angle dead zone and intermittent start-stop. The actuator is driven by the drive control signal to adjust the posture of the photovoltaic support, so that it can continuously and stably track the changes in the position of the sun throughout the day.

7. The method according to claim 6, characterized in that, The calculation of the solar altitude angle and azimuth angle includes: The GPS module is used to obtain latitude, longitude, and UTC, and longitude is corrected accordingly. In the event of a short-term signal failure, the real-time clock is invoked to maintain time updates; The solar declination angle, solar time difference, and solar hour angle are calculated by combining the date and time. Atmospheric refraction correction is performed when the altitude angle is less than a preset threshold, and orbital eccentricity correction is performed throughout the year to ensure that the overall calculation error does not exceed 0.05°.

8. The method according to claim 6, characterized in that, The acquisition of the real-time attitude information includes: The elevation angle data of the photovoltaic support is obtained by using a tilt sensor with a resolution of not less than 0.01° and a repeatability error of not more than 0.05°. The rotor position pulse signal is obtained by a Hall sensor installed inside the brushless motor; The sensor data is fused and filtered in the control unit to suppress noise and drift, thereby forming real-time attitude feedback for closed-loop control.

9. The method according to claim 6, characterized in that, The generation of the drive control signal includes: When the deviation is greater than 0.05°, the control unit uses a proportional-integral-derivative (PID) control algorithm to generate a correction control signal; When the deviation is less than or equal to 0.05°, the brushless motor drive unit maintains low-speed continuous operation.

10. The method according to claim 6, characterized in that, The ultra-low speed continuous operation of the brushless motor is achieved through the following methods: The control unit performs Clarke and Park transformations on the acquired three-phase current signals to obtain the direct-axis current and quadrature-axis current, and then compares them with reference values ​​before generating voltage commands through the current regulator. The voltage command is transformed by an inverter to obtain three-phase voltage components, and the target voltage vector is synthesized by space vector pulse width modulation to output a three-phase PWM duty cycle signal; The control unit performs closed-loop regulation of the current loop based on the real-time detection results of the current sampling circuit, and performs dead-zone compensation and overmodulation processing in the PWM signal to reduce voltage error and torque fluctuation in the low-speed range. When the angle deviation is less than the threshold, the control unit outputs a constant low-speed speed command, so that the brushless motor runs continuously in the range of 0.1 to 10 rpm, and controls the torque fluctuation to no more than 5% in the closed-loop control process, thereby realizing the smooth attitude adjustment of the photovoltaic support at ultra-low speed.

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