30w solar street light
Solar street lights are mainly composed of solar cell components, component brackets, electric control boxes (built-in controllers, batteries), light poles (including lamps and lanterns) and other parts. The system diagram is as follows:

Design Flow The design process of this system mainly includes: the selection of light poles, the selection of lamps, the configuration of solar modules, the configuration of batteries and controllers, and the setting of system protection measures. Selection of light poles The lamp pole is the supporting part of the whole street lamp, and has high requirements for its hardness, height, wind resistance, anti-corrosion, etc. The commonly used material is Q235, which is processed through a series of processes, and the surface is sprayed with an anti-corrosion layer of 80 μm. The system is installed on the main road, with a width of 30 meters, and is arranged symmetrically on both sides. According to the street lamp construction design specification (see Table 1), the system adopts light-cutting lamps, and the installation height is 10 meters (according to the standard, the installation height should be 15M, but considering that the higher the height, the higher the power of the lamps is required, and the design of the lamp poles The more complicated it is, after comprehensive consideration, the light pole is 12 meters, the installation height of the lamps is 10 meters), and the spacing is 30 meters. The diameter of the upper and lower openings of the lamp pole is Ф70/Ф250, the material thickness is 3.75mm, the taper is 11‰, the foundation size is 500500, the flange size and hole spacing are 40040018-300, and the base frame size is 300300 -Ф18. Table 1 The relationship between the light distribution type and arrangement of lamps and lanterns and the installation height and spacing of lamps

The choice of street light power

According to the requirements of road lighting standards for motor vehicle traffic (see Table 2) in the street lamp construction design specification, this system belongs to class I, and the average road surface illumination is 20 lux (lx). Then it can be concluded that the total luminous flux of the lamps is: total luminous flux = (average illuminance * maintenance factor * irradiation area) / (number of lamps * lamp utilization factor) = (200.915*30)/0.95=8526lm . Table 2 Standard values of road lighting for motor vehicle traffic

At present, there are many kinds of lamps used as road lighting, including high-pressure/low-pressure sodium lamps, energy-saving lamps, LED lamps, etc. Among them, LED has obvious advantages and is the trend of future road lighting. Its advantages are as follows:

  1. The LED has high lighting efficiency, long service life, and can be used for more than 50,000 hours; easy installation: no need to bury cables, no rectifiers, etc.; with a unique secondary optical design, the light of the LED street light is irradiated to the required lighting area, The lighting efficiency is further improved to achieve the purpose of energy saving;
  1. The high light source efficiency of LED has reached 90-110lm/W at present, and the light decay is small, the light decay in one year is less than 3%, and the illuminance requirements for road use are still met after 10 years of use.
  1. Low maintenance cost: Compared with traditional street lights, the maintenance cost of LED street lights is extremely low. After comparison, all investment costs can be recovered in less than 6 years. Based on the above principles, high-power LED street lamps have a significant energy-saving effect. Replacing high-pressure sodium lamps can save 60% of electricity. According to the power and luminous flux data of LED lamps on the market, it is more appropriate to choose 120W (DC 24V). There are two types of LED lights: AC and DC. In order to reduce cost and power loss, this system chooses DC LED lights, the model is D24/120. Note: The luminaire utilization factor refers to the ratio of the luminous flux projected onto a straight road of infinite length and a certain width to the output luminous flux of the LED luminaire. Battery and panel selection Selection process: (1) The daily power consumption of the load Q=WH/U=1208/24=40Ah. where U is the nominal voltage of the system battery (2) The charging current I1=Q1.05/h/0.85/0.9=401.05/4.46/0.85/0.9A=12.3A of the solar cell module that meets the load daily electricity consumption, where 1.05 is the solar charging comprehensive loss coefficient, 0.85 is the battery charging efficiency, 0.9 is the controller efficiency, and h is the standard peak hours, which is 4.46 hours. (3) The battery capacity is determined to satisfy the battery capacity that can work normally in 5 consecutive cloudy and rainy days CC=Q*(d+1)/0.81.1=406/0.81.1=330Ah where 0.8 is the depth of discharge of the battery, 1.1 For the safety factor of the battery, select 2 12V180Ah batteries in series to form a battery pack. (4) The charging current of the solar cell module that needs to restore the battery capacity after continuous cloudy and rainy days I2I2=C0.8/h/D=330*0.8/4.46/20=2.96A where 0.8 is the depth of discharge of the battery, and D is the two consecutive The number of days between cloudy and rainy days. (5) The power of the solar cell module is (I1+I2)*30=(12.3+2.96)*30=457Wp where 30 is the working voltage of the solar cell module, and two solar cell modules with a peak power of 230W are selected. Controller selection The controller is a key component that acts as a manager in the entire street light system. Its biggest function is to comprehensively manage the battery. A good controller should set various key parameter points according to the characteristics of the battery, such as the overcharge point of the battery, Over-discharge points, restore connection points, etc. The configuration and selection of the photovoltaic controller should be determined according to the technical indicators of the entire system and with reference to the product sample manual provided by the manufacturer. Generally, the following technical indicators should be considered:
  1. System working voltage Refers to the working voltage of the battery pack in the solar power generation system. This voltage should be determined according to the working voltage of the DC load or the configuration of the AC inverter. Generally, there are 12V, 24V, 48V, 110V and 220V.
  1. The rated input current and the number of input channels of the photovoltaic controller The rated input current of the photovoltaic controller depends on the input current of the solar cell module or square array. When selecting the model, the rated input current of the photovoltaic controller should be equal to or greater than the input current of the solar cell. The number of input channels of the photovoltaic controller should be more than or equal to the designed number of input channels of the solar cell array. Low-power controllers generally have only one solar cell array input, while high-power photovoltaic controllers usually use multiple inputs. The maximum current of each input = rated input current/number of input channels. Therefore, the output current of each battery array should be Less than or equal to the maximum current value allowed for each input of the PV controller.
  1. The rated load current of the photovoltaic controller That is, the DC output current output by the photovoltaic controller to the DC load or inverter, and this data must meet the input requirements of the load or inverter. In addition to the above-mentioned main technical data to meet the design requirements, parameters such as ambient temperature, altitude, protection level and external dimensions, as well as the manufacturer and brand are also factors to be considered when configuring the controller. This system selects a controller with a rated voltage of 24V and a rated current of 20A. 30w solar street light design scheme (2) Time-sharing and partial-voltage control of solar lights is to control the input power of solar lights according to people's different requirements for illuminance at different time periods at night, and the amount of energy absorbed by solar cells during the day, so as to achieve the lowest cost design that can meet the worst weather conditions. The purpose of the following people's most basic requirements for solar lights. The control circuit is suitable for lawn lamps with 12 LEDs as light sources. U includes circuits such as drive, light-controlled detection, pulse width modulation, and battery voltage detection. Pin 1 is the enable terminal, pin 2 is the power supply voltage terminal, pin 4 is the load current adjustment port, pin 5 is the switch port, pin 8 is the ground terminal, and pins 3, 6, and 7 are all floating. Changing the resistance value of R4 can change the working current of the LED, the maximum allowable current is 500mA, and the current is the smallest when M is grounded. J1 is a solar cell, J2 is a power switch, and J3 is a 2-cell NiMH battery. In order to reduce the tube voltage drop, VD1, VD2 can use Schottky diodes. Changing R5 and R6 can adjust the voltage division protection value of the battery, and changing R1 and R2 can adjust the time division value. The circuit can ensure the lighting time on the basis of reducing the cost of solar cells as much as possible, and has a high cost performance.

30w solar street light design scheme (3)

Solar street light controller made with PIC12F675 microcontroller

PIC 12F675 controls the overcharge and overdischarge of the battery, the function of turning on and off street lights, timing lighting, automatic lighting at dark, delayed lighting, automatic tracking lighting and other functions, street lamp lighting test control function, LED indication function, etc. . The power supply system is composed of battery BT1, battery overcharge control execution FET 01, and three-terminal voltage stabilizer U1; Q2, Q4. It is composed of discharge control; K1 manual, R_GM1 light-controlled automatic light-on system, battery voltage divider resistor, light-emitting indicator diode and other parts. The solar panel voltage is input by interface J3. After the anti-reverse charging diode D1, it is divided into two channels. One channel is regulated by U1 LM 78L 05 to provide working power for the PIC 12F675 microcontroller, and the other channel is used to charge the battery through the FB fuse. After the microcontroller is powered on, the hardware circuit composed of Rf and Cf is first reset. Then, the software controls U2 ③ pin GP4 to output high level, so that Q4 is turned on, Q2 is turned off, the control system stops discharging, and then the divided voltage value on U2 ⑦ pin GP0 is detected, and indirectly detected and judged through internal A/D conversion and software operation. Whether the battery is under-voltage or over-voltage. If the battery is overcharged, the software controls the pin GP5 of U2 to output a high level to make Q1 turn on. Short-circuit the solar panel, stop charging the battery, and turn on the "overcharge" indicator LED2 at the same time; if no overcharge occurs, the pin GP5 of U2 ② will output a low level to allow the battery to charge. By detecting the voltage division value of the photoresistor R_GM1 connected to U2 ⑥pin GP1, it is judged whether it has been "dark, it's time to turn on the lights", if it reaches the preset turn-on point, the software will control the output of u2 ③pin GP4 is low level, so that Q4 is turned off, 02 is turned on, and the street lamp is lit. If the light is not turned on, the program returns, and the above parameters are checked in a loop. K1 is the manual light-on button. Press K1 to turn on the street light. The single-chip microcomputer judges whether it is "dark" by detecting the partial pressure value on the photoresistor R_GM1, if it is dark. Then light up the street lights according to the design requirements, if not, the microcontroller enters the "test" function of the street light controller: the street lights will automatically go out after 2 minutes.

30w solar street light design scheme (4)

The circuit principle is shown in Fig. The circuit consists of a battery overcharge control circuit with U5 as the core, a battery voltage indication circuit with U4A ~ U4D as the core and a button switch KS1 circuit for displaying voltage, a battery overdischarge control circuit with U1B, and U1A. It is composed of a light-on detection control circuit, a light-on and delayed light-off and secondary light-on timing control circuit composed of U2, and an output control circuit composed of a control transistor Q2 to drive a relay. They are introduced as follows.

(1) Overcharge and overdischarge detection protection part The solar cell panel or array is input from the ① pin of the socket CZ1 and added to the positive pole of the anti-reverse charging diode D2. The negative pole of D2 is connected to the positive pole of the 12V battery, that is, the ③ pin of CZ1. When the controller is initially powered on, due to the action of C4, the pin ② of U5 is low level, the pin ③ outputs a high level, and Q7 is turned on; Q8 is turned off, allowing the solar cell to charge the battery. When the charged voltage of the battery is less than 14 . At 4V, the series voltage divider circuit composed of R13, (R38 + R39) is sent to U5 ②, ⑥ When the voltage is lower than 2 / 3 of the power supply voltage of U5, that is, less than 6V, the circuit maintains the charging state; with the extension of the charging time , the battery voltage gradually increases, when the voltage of U5 ②, ⑥ is higher than 2 / 3 of the U5 supply voltage, U5 ③ pin outputs a low level, Q7 is turned off, Q8 is turned on, discharge current to the solar panel, stop charging the battery . In the state of U5 ③ pin outputting low level, its ⑦ pin is turned on, which is equivalent to incorporating 1140 into the circuit. At this time, the voltage divider ratio of the circuit is: R38+ R39/R40/IRl3+ (R38+R39)/R40, it is not difficult to calculate, when the battery voltage is lower than the set value of 13V. The state of the circuit is reversed again, and the U5 ③ pin outputs a high level, allowing the battery to be charged. (2) Light-on detection method and control The solar panel is a very good photosensitive element, and its output current and voltage can change with the intensity and illuminance of the received light. This controller uses this principle to realize the control of lights on and off. The PVin input voltage of the solar panel is divided by R5 and R6 in series; it is added to the second pin of the operational amplifier U1A, and its ③ pin is connected to the voltage dividing point of R9 and R8+VR1. In the daytime, the output voltage of the solar panel is very high under the sunlight, and it is divided by R5 and R6 to make the voltage of pin U 1A ② higher than pin ③, pin U 1A ① outputs a low level, Q1 is turned off, and U2 has no power supply The voltage does not work, Q2 is cut off, the relay does not pull in, the system has no output voltage, and the street light does not work. As it gets darker, the output voltage of the solar panel decreases. The voltage of pin ② of UlA also decreases synchronously. When the voltage of pin ② of U1A is lower than pin ③, the comparator turns over, pin U 1A ① outputs a high level, Q1 is turned on, the timing circuit U2 is energized, Q2 is turned on, and JDQ1 is pulled in Light up the street lights. In the figure, VR1 is the adjustment potentiometer for the time when the street lamp is turned on. Adjusting VR1 can set the street lamp to light up at different times. DW1 is a clamping diode, its function is to prevent the input voltage of U 1A ② pin from being too high and damaged due to the high voltage received by the solar panel during the day. C1 is an energy storage capacitor, and its function is to prevent the instantaneous sudden change of the voltage at pin U1A ② from ignoring the street lamp by mistake. R14 is the feedback resistor. Its function is to make U1A a hysteresis comparator. Prevent and avoid U1A oscillating near the light-on point and turn on and off the street light repeatedly. (3) Street lamp delay circuit lighting, extinguishing control circuit The delay control circuit adopts CD4541BE programmable timing control chip, which has low power consumption, built-in programmable frequency divider circuit, and the maximum frequency division level is 65536. The controller is designed to turn on the lights and turn off the lights regularly. The adjustment range is: 2. 093 hours -11 . 93 hours. Regulated by V: R2 and VR3 controls respectively. (4) Battery stop discharge priority control circuit If the battery voltage is lower than its allowable termination discharge value when the street lamp is about to be lit or has been lit, Q4 is turned on. At this time, regardless of whether U1A outputs a high level or not, Q1 will be turned off, thereby protecting the battery from over-discharge damage. (5) Battery voltage indication circuit In order to let the on-site care and maintenance personnel know and grasp the status of the battery in time, the controller is equipped with an LED battery voltage indicating device, which indicates the battery voltage through the number of LLEDs lit.

30w solar street light design scheme (5)

Description The TPS61165 operates with an input supply voltage between 3V and 18V and can provide output voltages up to 38V. The device features an integrated switching FET rated for 40V and can drive up to 10 LEDs in series. It operates at a fixed switching frequency of 1.2MHz, which not only significantly reduces output ripple and improves conversion efficiency, but also allows the use of small external components. By default, the white LED (WLED) current is set by an external sense resistor, RSET, and the feedback voltage is regulated at 200mV. Regardless of the digital or PWM dimming method, the output ripple of the TPS61165 on the output capacitor is very small, and it does not generate the audio noise produced by ordinary on/off control dimming. To provide protection during open LED conditions, the TPS61165 disables the switch to prevent the output from exceeding the absolute maximum ratings. The PMP3598 uses the TPS61165 for a non-synchronous boost design. Additional circuitry built around the op amp not only implements the battery undervoltage/charge indication function, but also provides ORing between the solar panel and the battery input. In addition, the circuit also integrates the necessary overheating and overcurrent protection functions, and has a load disconnection feature.

The important advantage of this design is that it has very high efficiency and good LED current regulation performance. The TPS61165 operates in constant current mode capable of stabilizing the LED current. The CTRL pin can be used as a control input for both digital and PWM dimming. The dimming mode of the TPS61165 can be selected each time the device is enabled. Analog dimming can also be implemented by changing the feedback reference voltage. A 20k ohm variable resistor can be used to change the LED current for dimming purposes. The converter can boost the voltage from 6V to 10.5V at 350mA with a conversion efficiency of not less than 85%. This circuit can be used to drive three 1W LEDs or multiple 50mA LEDs with a total input power not exceeding 3W.

30w solar street light design scheme (6)

The solar lamp circuit shown in Figure 1 is a low-loss circuit that uses a 7W four-pin CFL (compact fluorescent lamp) and a 12V, 7-Ahr sealed maintenance-free battery. The efficiency of the inverter is greater than 85% and the quiescent current is less than 2mA. It has a parallel charge controller with battery overdischarge protection and overcharge protection. Low quiescent current, overdischarge protection and overcharge protection ensure long battery life. The preheating function of the inverter can avoid blackening of both ends of the CFL, thereby prolonging its service life. This circuit can be used as a reliable and compact portable light source in rural areas and as an emergency light system in cities. The parallel charge controller circuit includes IC1 (low current 2.5V voltage reference LM385) and IC2 (LM324 comparator). IC2A with resistors R1 ~ R8 and transistor Q1 prevents over discharge of the battery.

figure 1 This solar powered light driver can be used as an emergency light system. When the battery voltage is lower than 10.8V, this circuit cuts off the load (inverter and lamps), thus preventing the battery from over-discharging. Under no-load conditions, the voltage of the battery after discharge is about 12.2V, so to prevent oscillation, the circuit provides an over-discharge reset voltage of 12.3V. The red light-emitting diode LED1 indicates a low voltage state. IC2B with resistors R9~R14 and transistor Q2 prevents the battery from overcharging. When the battery voltage exceeds 14.8V, Q2 turns on and bypasses the solar array, preventing the battery from overcharging. When the battery voltage is lower than 12.5V, Q2 is turned off, and the solar panel array charges the battery. D2 is a reverse blocking diode. It prevents the battery from discharging the solar cell when the solar cell is not producing electricity. The yellow light-emitting diode LED2 indicates that the battery is fully charged. The green light-emitting diode LED3, together with IC2c and resistors R15~R20, provides charging indication.