CN201886356U - Automatic solar follow-up mechanism based on singlechip - Google Patents

Abstract

The utility model discloses an automatic solar follow-up mechanism based on the control of a singlechip, which comprises a solar battery board; a DC (direct current) electromotor is connected with the solar battery board; the DC (direct current) electromotor is connected with a driver; the driver is also connected with a control unit; the control unit is also connected with a photosensitive semiconductor, a photoelectric detection follow-up module, and a sun motion trail follow-up module. The automatic solar follow-up mechanism adopts the advantages of a photoelectric detection follow-up mode and a sun motion trail follow-up mode; during sunny days, the automatic solar follow-up mechanism adopts the photoelectric detection follow-up mode, uses an A/D switching circuit of a photosensitive diode to judge the position of the sun, and matches with a stepping motor to control the solar battery board to follow up the sunshine; during cloudy and rainy days, the automatic solar follow-up mechanism adopts the sun motion trail follow-up mode, and uses software to calculate the azimuth angle and elevating angle of the sun to follow up. The automatic solar follow-up mechanism based on the control of the singlechip can accurately control the rotating speed and rotating direction of a DC (direct current) motor and realizes operations on the motor, such as starting, positive rotation, negative rotation, etc.

Description

Solar automatic tracking device based on single chip microcomputer

technical field

The utility model invention belongs to the field of solar energy utilization. It relates to an automatic sun tracking control device with a single-chip microcomputer as the control core. The device can make a solar panel follow the change of the direction of sunlight irradiation and always keep perpendicular to the direction of the sun's rays, thereby improving the utilization efficiency of solar energy.

Background technique

At present, the development and utilization of natural energy by human beings has entered a new period, that is, the period of diversified new energy with solar energy and nuclear energy as the main body.

Solar energy is an ideal renewable energy with broad prospects for development and represents the development direction of the world's energy industry. At the same time, solar power has become the fastest growing technology in the world. In the past 25 years, the cost of solar power has dropped by 95%. . However, it also has disadvantages, such as low energy density, difficult to collect, unstable, and changes with seasonal climate and weather day and night, etc., so that the utilization of solar energy has problems such as intermittent, and the direction and intensity of light change continuously with time. The absorption and utilization of solar energy put forward higher requirements. At present, many solar panel arrays are basically fixed, which cannot guarantee the vertical irradiation of sunlight, and cannot make full use of solar energy resources, resulting in low power generation efficiency. According to experiments, in solar power generation, under the same conditions, the power generation of automatic tracking power generation equipment is 35% higher than that of fixed-angle power generation equipment. Therefore, in solar energy utilization, it is necessary to carry out sun tracking.

Contents of the invention

The purpose of this utility model is to provide a solar automatic tracking device based on a single-chip microcomputer. The device is controlled by a single-chip microcomputer. The entire circuit has a simple structure, high reliability, convenient operation and maintenance, and the speed accuracy of the motor can reach a higher level when the motor is in steady state operation. Static and dynamic indicators can better meet the requirements of tracking the sun.

In order to achieve the above tasks, the utility model takes the following technical solutions:

A solar automatic tracking device based on a single-chip microcomputer, comprising a solar panel, characterized in that a DC motor is connected to the solar panel, the DC motor is connected to a driver, the driver is also connected to a control unit, and the control unit is also connected to There are photosensitive semiconductors, photoelectric detection and tracking modules, and solar movement trajectory tracking modules.

Some other features of the utility model are:

Described control unit selects MC9S12DG128B single-chip microcomputer for use.

The DC motor is a 57BYG250-56 DC stepper motor.

The model of the drive is ZD-6560-V3.

The solar automatic tracking control device of the present utility model absorbs the advantages of both the photoelectric detection tracking mode and the solar motion trajectory tracking mode to make the operation of the device more flexible and also ensure the stability of the device, that is, according to the light intensity The corresponding tracking mode is used to track the sun, and the solar energy is received more efficiently in a more flexible mode. Due to the high cost performance of the device and the simple structure, it has practical value and promotion significance.

The technical effect that the utility model brings is:

(1) Low-cost sun tracking is realized by using a single-chip microcomputer. It has good wind resistance and strong practicability, and can realize all-weather sun tracking.

(2) Advanced microprocessor technology, strong anti-interference ability, wide temperature range, and reliable work in various harsh environments, which is unmatched by other models.

(3) The main circuit is simple, requires few power devices, high efficiency, and low power consumption.

(4) Different from the simulation debugging methods of most single-chip microcomputers, the background debugging module of MC9S12 provides convenience for the opening of single-chip microcomputers. BDM can dynamically debug single-chip microcomputers when they are running.

(5) Using PWM speed regulation drive control circuit, pulse width modulation (PWM) DC speed regulation technology has the characteristics of high speed regulation precision, fast response speed, good stability, wide speed regulation range and low power loss.

(6) The peripheral hardware and I/O resources are abundant, and most pins are multiplexed, which provides users with great flexibility.

(7) The experimental results show that the solar automatic tracking device of the present invention uses a motor to drive the solar panel control circuit to run stably and reliably, and the motor speed adjustment responds quickly, which can meet the requirements of practical engineering applications and has a good application prospect.

Description of drawings

Fig. 1 is the structural representation of the utility model;

Fig. 2 is a schematic diagram of the driver;

Fig. 3 is a display circuit diagram;

Fig. 4 is a key circuit diagram;

Fig. 5 is a schematic diagram of the principle of the photoelectric detection and tracking module;

Fig. 6 is a schematic circuit diagram of a photoelectric detection module;

Fig. 7 is the RS-232 driving circuit of the serial port;

Figure 8 is a flow chart when it is cloudy:

Fig. 9 is a flow chart of the clock module;

Fig. 10 is a flow chart of key module design;

Figure 11 is a flow chart of display module design;

Fig. 12 is a judgment subroutine flowchart;

Fig. 13 is the working state flowchart of motor;

Fig. 14 is the flow chart of calculating solar altitude and azimuth;

Below in conjunction with accompanying drawing, the utility model is described in further detail.

Detailed ways

The motor drive control device for the sun tracking system of the present utility model comprises a solar panel 1, a DC motor 2 is connected to the solar panel 1, the DC motor 2 is connected to a driver 3, the driver 3 is also connected to a control unit 4, and the control unit 4 Also respectively connected with photosensitive semiconductor 5, photoelectric detection and tracking module 6 and visual movement trajectory tracking module.

The control unit 4 adopts the Fressscale9s12 series single-chip microcomputer as the core of the whole system. The tracking system adopts the combination mode of the advantages of the photoelectric detection tracking mode and the solar motion track tracking mode. On sunny days, the photoelectric detection and tracking mode is adopted, using the photodiode as the sensor, using the A/D conversion circuit of the photodiode to judge the position of the sun, and cooperating with the stepping motor to control the solar panel to track the sunlight in real time. This mode has high light receiving efficiency; overcast and rainy When Tianshi enters the tracking mode of apparent solar movement trajectory, the software calculates the azimuth and altitude angle of the sun at that time to track, which ensures the stability of reception. The software and hardware of the device adopt modular design ideas, and the program is written in C language to complete the system design.

Control unit 4 chooses MC9S12DG128B single-chip microcomputer produced by Freescale; DC motor 2 chooses 57BYG250-56 DC stepping motor manufactured by Beijing Times Chaoqun Electric Technology Co., Ltd., and the driver chooses ZD-6560-V3. Realize the starting, forward rotation, reverse rotation and braking of the DC stepper motor.

, the overall design :

Select the Fressscale 9s12 series single-chip microcomputer as the core to control the circuit; after starting the device, the photosensitive semiconductor 5 judges whether it is sunny, if it is, enter the photoelectric detection and tracking module 6; Between 18:00, it means that it is a cloudy day, and the solar movement trajectory tracking module 7 is started to track; if not, it means that it is night, and the device does not work and resets automatically.

The photosensitive semiconductor 5 selects a photosensitive diode, adopts an A/D conversion circuit, and transmits the signal to the input and output ports of the single-chip microcomputer, and controls the motor after being judged by a predetermined program. In the solar movement track part, start the predetermined program, first read the current time, and then calculate the sun altitude and azimuth angle at that time, the single-chip microcomputer controls the motor deflection, and approximately aligns with the vertical angle of the sun to receive.

MC9S12DG128B single-chip microcomputer is a kind of M68HC12 series 16-bit single-chip microcomputer of Motorola Company, which can provide rich instruction system and has strong numerical operation and logic operation ability. Its internal structure is mainly composed of the basic part of the single-chip microcomputer and the CAN function block. The basic structure includes: a central processing unit HCS12 (CPU), 2 asynchronous serial communication ports SCI, 2 synchronous serial communication ports SPI, 8-channel input Capture/output comparison timer, 1 8-channel pulse width modulation module and 49 independent digital I/O ports (20 of which have external interrupt and wake-up functions), also has 128KB Flash ROM, 8KB RAM, 2KB of EEPROM. MC9S12's low-power crystal oscillator, reset control, watchdog and real-time interrupt and other configurations and functions are more conducive to the reliable operation of the system. Different from the simulation debugging methods of most single-chip microcomputers, the background debugging module of MC9S12 provides convenience for the opening of single-chip microcomputers. BDM can dynamically debug single-chip microcomputers when they are running. Most of the pins are multiplexed, providing users with great flexibility. Integrates A/D module, PWM module, clock module, etc., and these are exactly what this system design needs.

The CAN function block consists of two msCAN controllers compatible with the CAN2.0A/B protocol. These rich internal resources and external interface resources can meet the requirements of ECU for processing various data and sending and receiving CAN network data. The chip integrates Two msCAN12 modules can realize the gateway node function of high and low speed CAN network.

The clock circuit is the clock circuit of the standard MC9S12 single-chip microcomputer. By connecting a 16MHz external crystal oscillator to the external input interface EXTAL and XTAL of the single-chip microcomputer, the frequency is increased to 24MHz by using the voltage-controlled oscillator and phase-locked loop inside the MC9S12, as Internal bus clock for microcontroller operation.

This embodiment provides a set of solar automatic tracking device with MC9S12DG128B single chip microcomputer as the core and 57BYG250-56 DC motor as the carrier. The hardware circuit of the device includes: MC9S12DG128B single-chip microcomputer as the control unit, the minimum system circuit of the single-chip microcomputer, photoelectric detection and tracking circuit, PWM drive circuit, motor module, button circuit and display circuit; the software program part of the control unit is written in C language, compiled The environment is CodeWarrior 4.7, and the program is programmed into the S12 chip through the BDM provided by Tsinghua University.

, Photoelectric detection and tracking system design:

Figure 5 is a schematic diagram of the principle of the photoelectric detection and tracking module. As shown in Figure 5, a disk is placed on the solar panel, and then five photosensitive diodes are installed on the disk according to a certain distribution, in order to properly receive For sunlight and to avoid unnecessary interference, a hollow cylindrical sunshade needs to be placed outside the disc to filter and receive sunlight, and a light-transmitting hole should be added on the top of the cylindrical sleeve. Because the purpose of the setting is: when D0 in the center is irradiated vertically by the sun, the motor does not rotate, so the opening on the hollow cylindrical cover cannot be too large, otherwise it will irradiate other diodes and cause confusion; nor can it be too small , too small will lead to insufficient incident light, and the generated current signal is not enough to be received by the microcontroller. In view of the above reasons, the hole diameter is 6mm.

Assuming that the incident angle of the sun is not vertical at this time, but an angle of inclination θ, the height of the cylindrical cover can be calculated according to the needs of θ. Because the setting is that if D0 is detected to be a high potential, it proves that the incident sunlight is perpendicular to the solar panel at this time, then it will wait for 15 minutes and then check again, because the sun’s movement angle within 15 minutes is not large, but if the cylindrical cover is too short , it will cause 15 minutes later, the light still shines on D0, and even because the angle is not enough, the sunlight does not reach the surrounding photodiodes at all. In fact, the sunlight is not perpendicular to the solar panel at that time, which will reduce the receiving efficiency; On the contrary, if the cylindrical cover is too high, as long as the incident light angle deviates a little, it may cause the inner wall of the cylindrical cover, which may cause misjudgment and disorder.

The best situation is that within 15 minutes, the distance x that the sunlight moves on the inner disk of the cylindrical cover is not less than 2.5mm of the radius of the photodiode, but not more than 1.5 times the diameter of the photodiode + 6mm gap = 13.5mm. The following formula can be obtained:

And because the angle θ of the sun’s movement within 15 minutes is almost a fixed value, that is, the sun moves 180° in 12 hours during the day, and then moves 15° in 1 hour, so it moves nearly 4° in 15 minutes, so tg4°≈0.07, so it can be It is known that the value range of the height H of the cylindrical cover is: 36mm≤H≤193mm.

Therefore, try to avoid that the beam of light moves into the gap between the two diodes every 15 minutes, so take the height of the cylinder as H=40mm.

The sensor circuit consists of a sensitive element and an output circuit. In the design of this embodiment, the photosensitive diode is used as a sensor element to convert light signals into electrical signals. The role of the output circuit is impedance matching, amplification, and zero adjustment. So the output circuit consists of three parts: voltage follower, amplifier circuit and zeroing circuit. (As shown in Figure 6)

Because the collected signal is relatively small, generally a few millivolts, the voltage is sent to the single-chip microcomputer through the signal amplification circuit. In addition, in order to reduce the influence of the output offset voltage, especially when the op-amp is amplified by DC, a zero-adjustment circuit needs to be added. Finally, before transmitting the signal to the microcontroller, a limiter circuit is added to ensure that the voltage input to the microcontroller is within a certain amplitude. In this circuit, the voltage range only needs to be 0-5.1V.

Since there are five photodiodes, five such circuits are required. Connect with the ANOO-AN04 port of the single chip microcomputer in turn. The single-chip microcomputer judges the magnitude of the input voltage, and then controls the rotation direction of the motor.

, The minimum system design of single chip microcomputer:

The minimum system with microcontroller as the core includes clock circuit, serial port circuit, BDM interface, reset circuit, and power supply circuit. In addition, each power supply terminal and ground terminal of the microcontroller must be connected to a decoupling capacitor.

What this embodiment uses is the clock circuit of the standard MC9S12DG128 single-chip microcomputer, by connecting a 16MHz external crystal oscillator on the external input interface EXTAL and XTAL of the single-chip microcomputer, utilizing the voltage-controlled oscillator and the phase-locked loop inside the MC9S12DG128 to increase this frequency to 24MHz, as the internal bus clock of the microcontroller. Here, the PE7 pin is suspended, corresponding to XCLKS is high, and a series oscillator circuit is used.

There are two serial ports on the MC9S12DG128 chip, and the TTL level can be converted into RS-232 level through the RS-232 level conversion chip MAX232 in the serial port drive circuit, and then communicate with the PC through a 9-core serial cable. In addition, the single-chip microcomputer only needs to use a 6-pin plug to lead out the signal and connect it to the BDM debugger to realize the BDM debugging of the single-chip microcomputer.

, drive circuit and motor module design

PWM is a voltage adjustment method that changes the voltage at both ends of the load by controlling the switching frequency of the DC power supply with a fixed voltage, and then meets the control requirements. In the adjustment system of PWM drive control, the power supply is turned on and off at a fixed frequency, and the length of "on" and "off" time in a cycle can be changed as needed. (As shown in Figure 3) In this embodiment, PWM is required to send pulses to control the rotation of the motor, and the forward and reverse rotation of the motor is controlled by setting the output level of the K port of the microcontroller. R is a series resistor. When the interface voltage of the controller is 5V, there is no need for R, just connect it directly; when the interface voltage is 12V, please connect a 1K resistor in series; when the interface voltage is 24V, please connect a 2.7K resistor in series. For this device, connect (direction -) to the PK0 port of the single-chip microcomputer, when the output is high, it will rotate forward, and when it outputs low, it will reverse. (Offline-) share the ground with the microcontroller, add a manual switch in the middle, when the switch is off, the motor works normally, and off-line when the switch is on.

The tracking of the sun's rays is realized by controlling the rotation of the motor by the control unit. Tracking the position of the sun determines that the rotation angle of the motor is a random process, that is, the rotation angle of the motor is only related to the position at the previous moment as a function of time. Considering the tracking accuracy, the rotation of the motor must be precisely controlled, which determines the selection of a stepper motor.

Input a pulse, the angle at which the stepper motor rotates is called the step angle θ _b , and its calculation formula is as follows:

The speed n of the stepper motor is expressed by the following formula:

In the formula: f: the frequency of the input pulse (Hz); Z: the number of teeth of the rotor; N: the number of beats for the rotor to rotate through one tooth pitch.

It can be seen that during the working process of the stepping motor, the excitation state changes periodically, and every time a cycle of excitation state conversion is completed, the motor rotates a tooth pitch. Wrong teeth are the root cause of the rotation of the stepper motor, that is, the position and speed of the motor have a one-to-one correspondence with the number of conductions (pulse numbers) and frequency, and the direction is determined by the order of conduction. Therefore, the problem of motion control of a stepper motor is fundamentally to control the pulses input to the stepper motor. The model of the DC stepping motor selected in this embodiment is 57BYG250-56, the driving voltage is 24V, the current is 2A, and the step angle is 1.8°.

, Button circuit and display circuit design:

LED display is the most widely used one in single-chip microcomputer control, and there are many ways to interface with single-chip microcomputer. For example, 74LS274 and 74LS248 can be used to directly drive LEDs, and chips with latch function CD4511 and CD14513 can also be used to drive them. However, the output capacity of the general parallel port is insufficient, so it needs to be driven by current; the current on each LED should not be too large, otherwise it will be easy If the LED is damaged, a current limiting resistor must be added; if the dynamic refresh method is used, MCU resources will be occupied; if the static refresh method is used, too many devices will be used, and the circuit will be more complicated. At the same time, the CD4511 chip can only drive one LED display, so when the system needs to connect multiple LED displays, it will inevitably increase the number of hardware circuits, complicate the circuit, and increase the cost. Since the circuit needs to display the day, hour, and minute, multiple LED displays are required, so the display part of this embodiment is realized by using a 74LS245 chip (as shown in Figure 4).

为低电平时有效，DIR=“0”时，信号由B向A传输，（也就是接收）；DIR=“1”时，信号由A向B传输，（也就是发送）；当

为高电平时，A、B均为高阻态。74LS245 is used to drive LED or other devices. It is an 8-way in-phase tri-state bidirectional bus transceiver that can transmit data in both directions. The 74LS245 also has a bidirectional tri-state function, which can either output or input data. when

It is valid when it is low level, when DIR=“0”, the signal is transmitted from B to A, (that is, received); when DIR=“1”, the signal is transmitted from A to B, (that is, sent); when

When it is high level, both A and B are in high impedance state.

,software design

Software design plan: After starting up, power on, reset, and initialize. After initialization, first judge whether the light intensity at that time can enter the photoelectric detection and tracking mode. If so, enter the photoelectric detection and tracking module; if not, it depends on whether it is day or night. If it is night, the system does not work; if it is daytime, it means that it is cloudy, and then enter the tracking module of apparent solar movement trajectory.

In the photoelectric detection and tracking mode, firstly detect whether the light intensity received by the five photodiodes is greater than a certain value, and if so, then judge which photodiode has the highest light intensity, which means that the photodiode has received light. When the single-chip microcomputer commands the motor corresponding to the photodiode to rotate one step in the prescribed direction, the purpose of tracking the sun has been completed like this.

In the sun angle tracking mode, when it is cloudy, the photoelectric tracking mode cannot track accurately. If it is in a cloudy state for a long time, the device cannot track the sun in time, so the tracking error of the device will be large. The device is in a disordered state, so in order to improve the tracking accuracy, the device must be able to track normally even in cloudy days. The sun angle tracking mode is not affected by the intensity of sunlight, which just makes up for the defect that the photoelectric tracking mode cannot track normally on cloudy days. Figure 8 is a flow chart when it is cloudy.

When encountering a cloudy day, it is necessary to enter the solar movement track tracking module, and the altitude angle and azimuth angle of the sun need to be calculated according to the time at that time. Initialize the timer first, timing 1 millisecond, then 1 minute, 1 hour, one day, one month. Figure 9 is a flowchart of the clock module:

When designing the button module, for the 8 direct keys, they are arranged from high to low as follows:

Among them, S7-S4 can input 0-9 through setting and resetting, and the function settings of other bits are shown in the table below.

Refer to Figure 10 for the flow chart of key module design.

When the display module is designed, there are 4 LED digital tubes in the hardware circuit, which display the hour and minute respectively. PE3 port controls the output of tens of hours, PE2 controls the output of ones of hours, PM0 controls the output of tens of hours, and PM1 controls the output of ones of hours. The design flow chart is shown in Figure 11.

After the device is started, the sensor transmits the collected signals to the single-chip microcomputer. If the collected numbers are greater than a certain value, it means that it is sunny and enter the photoelectric detection and tracking mode. If they are all less than a certain value, it means it is cloudy or night. Then Look at the time at that time, if it is between 7:00 and 18:00, it means that it is cloudy, and enter the solar tracking mode, otherwise it means that it is night and the device does not work. After sorting out the collected signals, by taking the average value of the obtained values of each tube, set the lower limit value of light intensity as minimum, the upper limit of light intensity as maximum, and define the working mode as style. There are 3 types in total. Operating mode. If the average value of the 5 tubes is greater than the minimum, and it is in the daytime, it will enter the photoelectric detection tracking mode, style1=1; if the average value of the 5 tubes is less than the minimum, and it is in the daytime, it will enter the apparent day motion trajectory tracking module, style=2, otherwise at night, style=3, the device does not work. The flow chart of the judgment subroutine is shown in Figure 12.

When the system enters the photoelectric detection and tracking module, it is necessary to control whether motor A or motor B rotates, forward or reverse, or not, by comparing the values of ave[0]~ave[4], which determines the solar panel Turning up and down, left and right still doesn't move. In this way, there are a total of 5 working states of the motor, and assign values to cer respectively, from 1 to 5, to correspond to each working state of the motor one by one. The flowchart is shown in Figure 13.

When the system enters the tracking module of apparent solar movement trajectory, it needs to read the time at that time, and calculate the azimuth and altitude angle of the sun at that time through the formula (described in Section 2). After using the calculated solar altitude and azimuth, it is necessary to calculate the difference between the accumulated solar altitude and azimuth at a certain time interval (15 minutes), and divide this difference by the step angle of the stepping motor (1.8° ) The number of pulses required, and make the microcontroller send out the corresponding pulses. If the difference between the two times is within a certain range (defined as range), the motor will not rotate. The flow chart of calculating the solar altitude and azimuth is shown in Figure 14.

In summary, the solar automatic tracking device of the present utility model has the following characteristics:

(1) Using the MC9S12DG128B single-chip microcomputer produced by Freescale Company as the control unit, and using the 57BYG250-56 DC motor as the carrier, a set of DC motor drive device was produced. Freescale has a relatively large market share in the field of automotive single-chip control, and its product quality is relatively good, and it is easy to purchase and replace.

(2) Simple structure, strong practicability, small size, and easy installation.

(3) Advanced microprocessor technology, stable performance, high reliability, technology priority.

(4) The drive circuit can meet the needs of various types of small DC motors, and has the characteristics of fast, accurate, high efficiency, and low power consumption.

(5) Using PWM speed regulation drive control circuit, pulse width modulation (PWM) DC speed regulation has the characteristics of high speed regulation precision, fast response speed, wide speed regulation range and low power loss.

Claims (4)

1. one kind based on monolithic processor controlled solar automatic tracking device, comprise solar panel (1), it is characterized in that, be connected with direct current motor (2) on the described solar panel (1), direct current motor (2) is connected with driver (3), driver (3) also links to each other with control module (4), also is connected with photosensitive semiconductor (5), Photoelectric Detection tracing module (6) on the control module (4) respectively and looks daily motion trajectory track module.

2. solar automatic tracking device as claimed in claim 1 is characterized in that, described control module (4) is selected the MC9S12DG128B single-chip microcomputer for use.

3. solar automatic tracking device as claimed in claim 1 is characterized in that, described direct current motor (2) is selected 57BYG250-56 type dc stepper motor for use.

4. solar automatic tracking device as claimed in claim 1 is characterized in that, the model of described driver (3) is ZD-6560-V3.

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