Solar LED road lamp brightness control design

At present, in the field of high brightness LED street lamp driver, widely used at home and abroad mainly include power supply chip dedicated 'USES' and 'using discrete component of switch power supply,' the two main technical solutions, and to the need of 'intelligent', usually on the basis of the two plans to join the single chip microcomputer as main control chip of system management, so the two solutions can be summed up in 'management + power supply control system' 'more than traditional chip technology scheme', shortcomings using chip, the hardware structure more complicated, especially when the need in an LED street lamp driver driving multi-channel high brightness LED series, especially this kind of defect. Principle introduction

new Piccolo TMS320F2802x / 3 x MCU using the latest architectural technology and enhanced peripherals, its packaging size for at least 38 pin, can bring the 32-bit in low-cost applications the advantage of the real-time control function. Real-time control through such as solar micro inverter, LED lighting, large household appliances as well as the hybrid car batteries and other industrial, consumer and automotive applications implement advanced algorithms, which can achieve higher efficiency and precision of the system.

type Buck switching power supply is one of the widely used power supply solutions, by choosing suitable output inductor and switch frequency, can make the system work in the inductor current continuous mode; Based on TMS320F28027 LED Lighting Demo is based on the principle of the Buck type switching power supply, make full use of TMS320F28027 on PWM ( Up to eight road PWM output) And the ADC ( As many as 16 channel ADC) Peripherals such as resources and combined with the corresponding control algorithm to realize the current closed-loop control.

as shown, the system includes a main control chip TMS320F28027, drive circuit, switch components, information feedback network, storage system configuration of external storage, data acquisition interface and system extension interface and so on seven modules. Main control chip electric reset from off chip storage after loading destroy the LED brightness, light time, light out the way of parameters, such as set value as a control parameter, by means of these control parameters and feedback ( Including of grid voltage, collected data acquisition interface environment brightness, system parameters such as temperature) Algorithm processing, frequency and duty ratio of PWM signal, and then output PWM signals, after driving circuit amplifier is used to drive PWM signal in the switching power supply switch element, make the system to power supply, high brightness LED lights and LED street lamp voltage at the ends of the size and the size of the current through the LED lights are fed back to the main control chip, through feedback network in order to realize the calibration of the control effect. The expansion of the system to provide the interface to interact with other peripherals module for data, to facilitate the practical application of the function of the drive to expand, such as by extending the interface mount Zigbee and GPRS module, in order to realize the network management and remote maintenance of drive.

scheme characteristics based on TMS320F28027 high brightness LED drive single chip solution, the system of management and power control, reduced the complexity of hardware design, at the same time, both the output drive route design flexibility, can be controlled by changing the chip on the outskirts of the contents of the memory, the destroy of the LED current size, light brightness, bright out mode, environment and system temperature control parameters, such as custom, but also through the MCU data interface for network management and remote maintenance system. High brightness LED driver based on TMS320F28027 single chip solution has the following characteristics:

low cost -- — Single chip solution to multi-channel constant current control, save for constant current chips, effectively reduce the system cost

efficient - — The isolating switch power supply, there is no loss in the transformer magnetic flux leakage, high conversion efficiency, the system load when the overall efficiency is as high as 95%

drive ability - — 8-way unfenced constant current driver output, can drive the 8 series ( Each string of not less than 14) Not less than 100 w leds, the total output power control flexible

-- — Using high performance DSC as control core, can give full play to the advantages of 32-bit real-time control function, each way of destroy road LED the current size, light can be independently controlled

good scalability - — Reserved, such as temperature, brightness, color temperature detecting interface, support data such as serial interface, I2C interface, has laid a good groundwork for system integration ( Such as LED street light for Zigbee network, extend GPRS module, etc. )

in addition, the scheme supports 12 ADC resolution, support 256 step gray-scale control; Wide input voltage, the additional system power source, the input voltage up to 100 v; When sharing all the DC power supply control system and LED string, up to 60 v; Supports under-voltage lockout and over voltage protection, over temperature protection extension, no-load test, over-current protection, brightness automatically save power, four-channel packet delay noise reduction.