Single chip high power solar LED street light circuit design and simulation analysis

　　1 Introduction

　　As the fourth generation of lighting sources, LED is being used more and more widely in urban beautification, road lighting, garden lighting, indoor lighting and other fields with its unique advantages. Especially in remote areas without electricity, solar lighting fixtures are rapidly promoted and applied with their irresistible advantages. An author discussed the installation of solar panels in LED lamps, the functions of controllers, the placement of lead-acid batteries and constant current drive circuits, but did not give the design and simulation of key circuits such as controllers. Other authors explained the principles that should be followed in the design of LED street lights from three aspects: light source design, drive circuit design and heat dissipation design, but the circuits used were not intelligent and could not be controlled by programs.

　　This paper designs and simulates a solar LED street light with a power of about 40W based on AT89C52 single-chip microcomputer intelligent control. It adopts dual power supply mode, has light control and time control functions, and has strong anti-interference ability. This paper mainly introduces the design of the solar LED street light light panel, the selection of solar cells and batteries, and analyzes and discusses the circuit design and working principle of each part of the street light in detail. Protues and keil software are used to simulate the charging circuit, boost circuit and control circuit of the LED street light. The simulation results are consistent with the design indicators.

　　2. Solar LED Street Light Hardware Circuit Design

　　2.1 System Hardware Composition

　　The solar LED street light system is mainly composed of solar cell components, LED lamps, lamp poles and control boxes (with chargers, controllers, batteries, etc.). The total power of the solar LED street light designed in this paper is about 40W. The structural schematic diagram of the circuit is shown in Figure 1. It can be seen that the system uses dual power supply. The system circuit is mainly composed of solar cells, batteries, charging circuits, boost circuits, control circuits, LED drive circuits and LED arrays.

　　Figure 1 Solar LED street light system structure

　　2.2 LED working principle and circuit design

　　LED is sensitive to voltage. This design uses 30 white light LEDs of model HKP2D1W1 manufactured by Hangke Electronics. From the LED characteristic curve shown in Figure 2 (A), it can be seen that when the forward voltage reaches 314V, the forward current will change greatly as long as the forward voltage is slightly changed. In order to obtain the expected brightness and avoid the forward current exceeding the maximum rated current of the LED, the LED driving method used in this article is current driving.

　　The LED array is in the form of 5 rows and 6 columns, and the circuit is shown in Figure 2 (B). The LEDs are from the same company and the same batch, so it can be assumed that the characteristics of each LED are basically the same. Therefore, the current flowing through each column of LEDs is 350mA, which is the typical operating current of this model of LED. The lighting power of the system is about 40W, and the luminous flux is about 1200lm.

　　Figure 2 LED characteristic curve and full array diagram