CN103904987A - Two-degree of freedom solar tracker - Google Patents

Abstract

The invention provides a two-degree-of-freedom solar tracking device. The utility model comprises a solar panel installation groove installed with a solar panel, a pitch rotating shaft, a bracket, a horizontal rotating shaft, a pitch motor, a platform, and a horizontal motor. On one side of the placement groove of the solar panel, there is a sun direction detection device installation groove fixed. The sunlight direction detection device includes a control box with a control circuit installed. The lower part of the control box is fixed with a mounting pin. The exact same photocell and two light-tight baffles, the two light-tight baffles are installed vertically to each other, four photocells are symmetrically arranged on both sides of the two light-tight baffles, and the sunlight direction detection device is installed through the installation pin In the installation groove of the sunlight direction detection device, the signal of the photocell is input to the control circuit, and the control circuit controls the pitch motor and the horizontal motor. The invention is a follow-up device which can timely and correctly align the sun on the two degrees of freedom of the horizontal and the pitch.

Description

A two-degree-of-freedom solar tracking device

technical field

The invention relates to a solar tracking device, in particular to a follow-up device that aligns the sun in time and correctly in two degrees of freedom, horizontal and pitch.

Background technique

Among the new energy sources, photovoltaic power generation is the renewable energy technology with the most ideal characteristics of sustainable development, and it has received widespread attention from all over the world. Now my country's solar photovoltaic power generation technology has become mature and has been popularized and applied. It has become a key technology for photovoltaic power generation to collect solar energy efficiently and improve the utilization rate of solar energy. Professors KPcheung and scMHui from the Department of Architecture of the University of Hong Kong studied the relationship between the sun’s illumination angle and the solar energy reception rate. Theoretical analysis shows that the energy reception rate differs by 37.7% between the sun’s tracking and non-tracking. Therefore, the use of solar servo tracking devices can fully improve the solar energy utilization rate. The device can make the solar panel always perpendicular to the sunlight and move with the movement of the sun, so as to achieve the purpose of automatic tracking.

There are many ways to automatically track the sun at this stage. One is to use the clock circuit control or the pulse generation circuit control method alone. Implement spacing adjustments. The other is a control method based on a single-chip microcomputer combined with related circuits. The basic principle is to use a control program to drive the motor to move. There is also a control method based on GPS and GIS, which is complex but can achieve high control accuracy. There are also methods that use photosensitive devices alone. The above methods can effectively utilize solar energy resources and provide better solutions for improving the utilization rate of solar energy. However, some of these solar tracking devices have complex structures and high cost, and some have low cost but poor system adaptability. Realize high control precision and low price cost.

The patent document with application number 201020569659.6 and titled A Tracking Control System provides a low-cost, high-precision sun tracking system, which consists of photoelectric sensors, controllers, limit switches and DC motors. However, this technical solution takes out the difference current of the sensors on both sides of the visor as a detection circuit. In the case of clouds and other conditions that lead to weak sunlight, the signal generated by the detection circuit may be biased compared with the sunlight on a sunny day, thus affecting to the accuracy of the results. The patent document with the application number 201010260613.0 and titled Sun Automatic Tracking Method and Device provides a method of using the shadow of the pointer on the disk surface to cause the voltage difference of the photocell placed in the opposite direction to detect its deviation from sunlight, but this The technical solution also does not take into account that different deviation values detected by the voltage detector under different light intensities affect the accuracy of the result.

Contents of the invention

The object of the present invention is to provide a two-degree-of-freedom solar tracking device with high control precision, simple structure, low cost and wide adaptability.

The purpose of the present invention is achieved like this:

The solar panel placement slot with the solar panel installed is fixed on the pitching shaft, the pitching shaft is supported by a bracket, the bracket is fixed on the horizontal shaft, the pitching motor that drives the pitching shaft to rotate is installed on the bracket, and the horizontal shaft is installed on the platform, The horizontal motor that drives the horizontal shaft to rotate is installed on the platform, and a sunlight direction detection device installation groove is fixed on one side of the solar panel placement groove. The sunlight direction detection device includes a control box installed with a control circuit, and the lower part of the control box is fixed. The upper part of the control box is equipped with four photocells of the same size and the same area and two light-proof baffles. The two light-proof baffles are installed perpendicular to each other. On both sides of the board, the sunlight direction detection device is installed in the installation groove of the sunlight direction detection device through the installation pin, the signal of the photocell is input into the control circuit, and the control circuit controls the pitch motor and the horizontal motor.

The present invention may also include:

1. There is a certain distance between the two opaque baffles.

2. The two opaque baffles form a cross.

3. Set up a protective cover outside the light-proof baffle and photocell.

The invention provides a device that can automatically adjust the orientation of a solar battery panel according to the direction of sunlight, so that the solar battery panel is perpendicular to the sunlight, thereby effectively improving the utilization rate of solar energy. The device works during the day and stops at night, which can overcome the interference of control accuracy caused by different sunlight intensities in different weather conditions, and can overcome the interference of lightning light to it. The overall structure of the device is simple and practical, and the price and cost are low. At the same time, it realizes high control precision, and does not require manual intervention. It has wide adaptability, is especially suitable for unattended situations, and has good promotion and application value.

The invention includes an overall structural device for placing solar panels that can be rotated in the horizontal and pitch directions, a sunlight direction detection device, a control circuit to drive a stepping motor, and through detection, amplification, comparison, and detection of sunlight signals, Judgment, give the motor a signal to rotate or not, and the motor drives the solar panel to make it perpendicular to the sunlight. The control circuit is mainly composed of a signal amplifier, a signal comparator, a judgment circuit and a drive circuit. The sunlight direction detection device mainly uses photocells, without additional power supply, to obtain the deviation signals between the normal line of the solar panel and the sunlight in the pitch direction and horizontal direction, respectively, and then generate driving signals through the control circuit to drive the stepping motor, so that the whole The structural device rotates in the pitch direction and the horizontal direction until the normal line of the solar panel points to the sun accurately.

The beneficial effect of the present invention is that: for the sunlight direction detection device, most of the traditional inventions are implemented by using photoelectric sensors, photoresistors, etc. Although these elements can convert optical signals into electrical signals, the obtained electrical signals will vary with the light intensity . However, in different environments and different seasons, the intensity of sunlight is also different, which will directly lead to different signals obtained by the sun tracking device under the same detection deviation, thereby affecting the accuracy of the results. However, the present invention adopts a photocell, which effectively avoids the problem of light intensity, and the photocell can provide electric energy, so that the detection device does not need an additional power supply. Furthermore, the control method of the device of the present invention uses a division operation circuit for the comparison of voltage deviations, further avoiding the problem of light intensity.

Description of drawings

Figure 1 is an overall structural diagram of a two-degree-of-freedom solar tracking device.

Figure 2-a and Figure 2-b are sunlight direction detection devices.

Figure 3 is a block diagram of the control circuit.

Figure 4 is a control circuit diagram.

Detailed ways

The present invention will be described in more detail below with examples in conjunction with the accompanying drawings.

Referring to FIG. 1 , the solar panel placement groove 9 is fixed on the pitch shaft 6 so that it can rotate synchronously with the pitch shaft 6 . The pitch rotating shaft 6 is supported by a bracket 5, and the bracket 5 is fixed on the horizontal rotating shaft 7. Both the pitching motor 3 and the horizontal motor 4 are stepping motors, which respectively drive the pitching shaft 6 and the horizontal shaft 7 to rotate on two degrees of freedom. Arrange a circular slot 1 for placing the sunlight direction detection device outside the frame of the groove 9, for the placement position, any place of the four frames of the groove 9 can be selected, but try to avoid being affected by the shadow of other devices. When installing the sunlight direction detection device, the cylindrical pin 13 in Figs. 2 and 3 must be installed in the placement groove 1 of the sunlight direction detection device in Fig. 1 . The solar photovoltaic panel is then fixed on the groove 9 and the control circuit board is placed in the control box 12 . In FIG. 1 , the connection between the photocell 11 and the control circuit board and the motor, and the linkage between the motor and the rotating shaft are not shown.

The sunlight direction detection device includes a control box with a control circuit installed, the lower part of the control box is fixed with a mounting pin, and the upper part of the control box is equipped with four photocells of exactly the same size and area and two light-proof baffles. One of the following two ways can be selected for the installation of the photocell and the two light-tight baffles:

Option 1: In combination with Fig. 2-a, two photocells 11 of exactly the same size and area are placed next to each other on both sides of a light-tight baffle 10 to form a detection device in one degree of freedom. Another two photocells with exactly the same size and area are arranged adjacent to the two sides of another light-tight baffle to form a detection device in a degree of freedom. Two detection devices are respectively placed in the east-west direction and one in the north-south direction, and the two light-tight baffles are separated by a certain distance, so that the two-degree-of-freedom control can be realized.

Option 2: Combining with Figure 2-b, place two opaque baffles crossed in a "cross" shape, and place a piece of photoelectric cells of the same size and area at each of the four corners of the intersection, numbered 11-1 respectively , 11-2, 11-3, 11-4.

Compared with Option 1, Option 2 is more compact in installation and more sensitive in response. Because in the device shown in Scheme 2, only one photovoltaic cell receives light to generate electric energy, it can cause the device to act in two different directions (the two directions are not opposite) at the same time, thereby increasing the sensitivity of the device's response.

The control principle implemented by the control circuit is shown in Figure 3, the electric signal generated by the photocell 11 is relatively weak, so a signal amplifier is required, and the signal amplifier can also function as a filter. The comparator is mainly used to compare the detected signal with the signal in the direction of sunlight vertically irradiating the solar panel to obtain a deviation signal, and the judgment circuit can judge whether the motor should be "forward" or "reverse" according to the obtained deviation , to get the driving signal. The drive circuit mainly plays the role of power amplification and is used to drive the stepper motor to rotate.

The device of the present invention requires the control accuracy to be less than ±3°. For the sunlight direction detection device shown in Fig. 2-a and Fig. 2-b, assuming that the width of a single photovoltaic cell is 1 cm, and the photovoltaic cells 11 in the present invention are connected in parallel in two rows, then Its width is a=2cm, and α=3° is taken, and the height of the opaque baffle 10 can be calculated as b≈38.17cm. Calculated as follows:

$\mathrm{<span\; class="notranslate">\; the\; tan</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; a</span>}}{\mathrm{<span\; class="notranslate">\; b</span>}}$

The device of the present invention can choose an opaque baffle with a height of 40 cm, which can not only meet the control accuracy, but also reduce mechanical wear and achieve the best effect. In order to protect the photocell from external environment such as wind or rain, a protective glass cover 14 is installed.

For the two schemes shown in Fig. 2-a and Fig. 2-b, in Fig. 2-a, the photovoltaic cells 11 placed on the two degrees of freedom can be respectively connected to the corresponding control circuits. For the scheme shown in Figure 2-b, when the device measures the deviation in the east-west direction, the photocells 11-1 and 11-2 must be connected in series, and the photocells 11-3 and 11-4 must be connected in series, and then connected to the control circuit correspondingly; when the device When measuring the deviation in the north-south direction, the photocells 11-1 and 11-4 must be connected in series, and the photocells 11-2 and 11-3 must be connected in series respectively, and then connected to the control circuit correspondingly.

As shown in Figure 4, the specific control idea implemented by the control circuit is:

The photocells 11 on both sides of the opaque baffle 10 generate voltage signals, respectively marked as u ₁ and u ₁ ′, and the signal amplifier adopts a first-order low-pass filter LPF, wherein R ₄ and R ₅ and the integrated operational amplifier form a proportional circuit of the same phase , not only can filter out the high-frequency waves to eliminate the interference of lightning in the air, but also can scale up the detected electric signal generated by the photocell 11. The voltage obtained after the signal amplifier is recorded as u ₂ and u ₂ '.

The comparator adopts a division circuit, which has the advantage of overcoming the different voltage deviations generated by the photocells 11 on both sides of the opaque baffle 10 due to the different intensity of sunlight caused by cloudy days and other conditions when the device is in the same position. The voltage signal passed through the comparator is recorded as u ₃ , then u ₃ is proportional to the quotient of the two input terminal voltages u ₂ and u ₂ ' and is inversely phased, so an inverter needs to be connected after the division circuit, then u ₄ and u ₃ are equal in size and opposite in direction.

The judging circuit is composed of two hysteresis comparators and some resistors to form a voltage comparator with Schmitt characteristics. The reverse connection of the two hysteresis comparators is to give two different driving signals, one is used to drive the motor to rotate forward or not, and the other is to drive the motor to reverse or not to rotate. The reference voltage _UR can be adjusted by the However, it may cause the problem of abnormal flow of current. The solution to this problem is to use a voltage regulator tube to connect a potentiometer in parallel and then connect a voltage follower in series. The voltage follower has high input impedance and low output impedance. The characteristics, so as to play the role of buffering, isolation, and improving the load capacity. The +VCC of the judging circuit in Figure 4 generally uses a voltage of +15V. The function of connecting the resistor _R1 is to allow the solar tracking device to have a no-action dead zone, that is, the resistor _R1 provides a dead zone voltage to prevent this The "frequent movement" of the mechanical device causes mechanical wear. Whether it is in the hysteresis comparator or at the reference voltage terminal, all voltage regulator tubes are 2CW14 voltage regulator tubes, and their stable voltage value is about 6V ~ 7.5V. When selecting the resistance value, it is necessary to make r ₂ /r ₁ ≥ 100, generally if r ₁ is selected as 100Ω, r ₂ is 10KΩ, and R ₁ < R ₂ is required at the same time, and the threshold voltage of a hysteresis comparator circuit is guaranteed to be the same regardless of the value of the potentiometer within the allowable range Positive or negative, and their hysteresis is similar in size. The voltage reference value u ₅ ' of the judging circuit needs to be realized by adjusting the potentiometer: when the sunlight irradiates the solar photovoltaic panel 2 vertically, u ₁ =u ₁ ', u ₂ =u ₂ ', then adjust the potentiometer to make the judgment The voltage value of the middle point 5 of the circuit u ₅ '=u ₄ . When sunlight intersects the normal line of the solar photovoltaic panel 2, the electricity generated by the photovoltaic cells 11 on both sides of the opaque baffle 10 is different. If u ₅ > u ₅ ′ and gradually increases, the judging circuit follows the forward rotation The voltage transmission characteristic is used to give the motor signal; if u ₅ >u ₅ ', and gradually decreases, the judging circuit gives the motor signal according to the reversed voltage transmission characteristic.

The drive circuit is implemented by a solid state relay, which amplifies the power of the control signal generated by the judgment circuit, and then realizes the function of driving the stepper motor.

Claims (4)

1. a two degrees of freedom solar energy tracking device, the solar panel resettlement groove that solar panel is installed is fixed in pitching rotating shaft, pitching rotating shaft is by stent support, support is fixed on horizontal rotating shaft, the pitching motor that drives pitching rotating shaft to rotate, rack-mount, horizontal rotating shaft is arranged on platform, the horizontal motor that drives horizontal rotating shaft to rotate is arranged on platform, it is characterized in that: on a limit of solar panel resettlement groove, be fixed with sunlight direction detection device mounting groove, sunlight direction detection device comprises the control box that control circuit is installed, control box bottom is fixed with mount pin, control box top is provided with four sizes, the identical photocell of area and two light tight baffle plates, two mutual at right angle settings of light tight baffle plate, four photocells are symmetrically arranged in two light tight baffle plate both sides between two, sunlight direction detection device is arranged in sunlight direction detection device mounting groove by mount pin, photronic signal input control circuit, control circuit control pitching motor and horizontal motor.

2. a kind of two degrees of freedom solar energy tracking device according to claim 1, is characterized in that: certain spacing of being separated by between two light tight baffle plates.

3. a kind of two degrees of freedom solar energy tracking device according to claim 1, is characterized in that: two light tight baffle plates are right-angled intersection.

4. according to a kind of two degrees of freedom solar energy tracking device described in claim 1,2 or 3, it is characterized in that: at light tight baffle plate and photocell, protective cover is set outward.

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