Design And Analysis Of Intelligent LED Solar Street Lamp Controller

- Jul 11, 2019-

1.The solar LED street lamp lighting system adopts the complementary mode of municipal electricity, which has practical and economic significance to promote the application of solar LED street lamp. In order to realize the complementary control of solar LED street lamp, a kind of controller of solar street lamp with complementary LED is designed. The controller takes ARM processor as the core, by sampling battery voltage, solar cell voltage, environmental temperature and other parameters, enter ARM operation decision, can realize high accurate control of temperature compensation and correction, and has battery selection function and automatic switching function of municipal power supply. The controller is applied in street lamp reconstruction, which can not only reduce the one-time investment, but also achieve significant energy saving and emission reduction effect.

  Solar energy as a "inexhaustible, inexhaustible" green, clean energy, is rapidly being widely used. LED has the characteristics of small size, rugged, low power consumption, long service, environmental protection and good light and color performance. Solar cell output is direct current, and LED is also dc drive light source, the two are easy to match, can obtain a high utilization rate, and reduce the cost, so LED solar street lamp more and more attention.

  Because the solar energy is restricted by weather factors relatively large, the distribution density of sunlight irradiation is small, the light time, intensity size has random intermittency, to ensure the stability of the output voltage of solar cells, it is necessary to use the battery to store electric energy, in the daytime when there is sunlight to charge the battery, the battery to the load discharge at night. If continuous rainy weather is taken into account, the battery capacity requirement is larger, and the solar battery pack capacity is larger and the cost is higher. The solar LED street lamp lighting system can solve this contradiction by adopting the complementary mode of municipal electricity, which has practical and economic significance for promoting the application of solar LED street lamp.

2.(1). Composition of mains complementary LED solar street lamp system

The so-called complementary LED solar street light system, electric is given priority to with the solar cell power generation, supplemented by ordinary 220 v ac power auxiliary LED street lamp lighting system, adopt the system, photovoltaic battery and battery capacity can be designed to be smaller, basically is the sunshine during the day, the day the day use solar power to the battery charging at the same time, the battery discharge load LED light in the dark. In most areas in China, the year basically more than two-thirds of good weather, so the system for more than two-thirds of time using solar energy light lamps, add energy to rest with the utility, both reduced the one-time investment of solar pv lighting system, and has obvious effect of energy conservation and emissions reduction, is a solar LED street lamp lighting at this stage of the effective methods to promote and popularize.

  As shown in figure 1, LED solar street lamp system is composed of five parts: solar cell, street lamp controller, battery, municipal power supply, switching power supply and LED street lamp. Among them, the street lamp controller is the control core of the whole system, which is used for battery charge and discharge control, LED street lamp on and off control, automatic switching control of municipal power supply and related protection control, etc. Solar cells are used to convert solar energy into electricity, and the street lamp controller determines whether it is day or night by collecting the voltage of the solar cell. The battery is the whole system In the daytime, the solar cell will charge the battery. In the evening or rainy day, the LED street lamp will be powered by the battery, and the street lamp controller can collect the battery voltage, and switch to the municipal power supply when the battery power supply is insufficient.

2.1 power input part

The power input part includes the reverse connection protection circuit and charge-discharge and power supply switching circuit, which play a protective role in the input of mains electricity, storage battery and solar cell. The switching circuit of charge, discharge and power supply realizes the switching between municipal power supply and battery power supply, and realizes the charging control of solar cell on battery and battery discharge control. Meanwhile, power supply is provided to MOSFET voltage stabilizing and short-circuit protection circuit of output part.

2.2 data acquisition and display control section

The data acquisition and display control part includes control key, LED display circuit, voltage and current acquisition, temperature acquisition, photosensitive acquisition and equalization circuit. The control keys include test keys, menu selection keys and parameter selection keys. The test key can make the controller enter the test state; The menu selection key is used to select the working mode. When the menu selection key is pressed, the mode value will be changed once and the corresponding parameters in this mode will be displayed. At this time, the operation parameters in this mode can be set by pressing the parameter selection key. Important data such as system operation mode and parameters are stored inside the chip, which will not be lost after power loss, making the adjustment more convenient and the system more reliable. LED display circuit including five leds status display and the operational parameters of two digital tube display, five LED light-emitting diodes (leds) used to display the solar cells, batteries, mains, the working state of the load, load 1, 2, 2 digital tube display mode respectively when the parameters setting and the parameters of this mode, when not to set parameters according to temperature. Voltage collection, current collection, temperature collection and photosensitive collection respectively complete the collection of battery and solar cell voltage, discharge current, temperature state and illumination, and provide these signals for the ARM processor operation processing, the voltage and current collection circuit is controlled by the ARM processor, so as to control whether the equalization circuit works.

2.3 ARM processor part

The ARM processor adopts philips ARM chip LPC2134, which is a high-end 32-bit real-time processor and is at the core of the whole system. Analyze and process the data collected by the collection module, make corresponding decisions, control charge-discharge and power supply switching circuit, voltage and current collection circuit, MOSFET voltage stabilizing and short-circuit protection circuit and soft switch, and realize charge and discharge control of battery, protection control of controller, and on-off control of output load. When solar battery supply power to load properly, mains by means of the charge and discharge controller and switching power supply circuit, voltage stability and short circuit protection circuit and the soft switch, can automatically separate the load power supply rather than directly to the battery of the above method, can reduce the damage of the accumulator and mains power, electric power configuration can effectively reduce the mains supply. The whole switching process to achieve soft switching, will not impact the load and battery, load work is not affected.

2.4 output part

The output part includes MOSFET voltage regulator and short circuit protection circuit and soft switch. Under the control of ARM processor, MOSFET voltage stabilizing and short-circuit protection circuit realizes short-circuit protection and voltage stabilizing output, and soft switch realizes independent on-off control of double-circuit output.

3. Street lamp controller software design

After completing the self-check and initialization program, the controller reads various set parameters, such as working mode, battery type, etc., and then enters the day and night judging program, which respectively enters the day processing program or night processing program according to the judged conditions. Judgment can be read by a solar cell, day and night at the ends of the voltage to judge, but can be by acquisition controller interface signals to judge reserved photosensitive sensor, controller in the software program design also can increase the two road load double session control function, double time control is to point to two road load of night lights and lighting time can be set up in the morning, is set to double time, load night lights closed after a period of time, the lights again before dawn, and wait until the day when closed, and the lighting time is adjustable.

Figure 7 test function software flow

After the controller is powered on, the operating mode and related parameters can be set by pressing the button. Controller software program designed to increase the battery selection procedures, support opening sealed battery, battery, gel battery, lithium battery, such as the use of the battery, before using, need to choose the right type battery, through the pressure setting on the control circuit board menu button to enter battery type selection model, and then by press the Settings in the control circuit parameters on the select button battery type selected, set 30 s, after waiting for parameters will be automatically saved, and the controller at run time based on the set of storage battery parameters under the action of ARM processor program automatically choose match the parameters of the operation. When the battery is set as lithium battery, the ARM processor will send out control signals to make the equalization circuit effective, so that the capacity of each battery cell of lithium battery remains equal, extending the service life of lithium battery.

4, endnotes

The LED street lamp controller designed in this paper has the function of battery selection, supports a variety of different batteries, and has the function of temperature compensation, which can effectively extend the service life of the battery, and has the function of complementary automatic switching between mains and mains. The controller is applied to the street lamp transformation, which can keep the original main-electric power supply line and lamp pole still, and replace the LED light source, thus forming the main-electric complementary LED solar street lamp. The investment will be greatly reduced, and the energy saving effect is significant.