Principle of energy-saving street lamp and its design analysis
来源: | 作者:ugatlighting | TIME :2020-05-23 | 46 次浏览 | 分享到:
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 string,This weakness is particularly acute.

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 string,This weakness is particularly acute.

Introduction of the principle

The new Piccolo TMS320F2802x/3x MCU USES the latest architecture technology and enhanced peripherals, with a minimum package size of 38 pins, to bring the advantage of 32-bit real-time control in low-cost applications.Real-time control enables higher system efficiency and precision by implementing advanced algorithms in industrial, consumer and vehicle-mounted applications such as solar microinverters, LED lighting, large household appliances, and hybrid on-board batteries.

Buck switching power supply is one of the most widely used power supply solutions. By selecting the appropriate output inductor and switching frequency, the system can be operated in the mode of continuous inductive current.LED Lighting Demo based on TMS320F28027 is based on the Buck switching power supply principle, which makes full use of peripheral resources such as PWM(up to 8 channels PWM output) and ADC(up to 16 channels ADC) on TMS320F28027 and realizes current closed-loop control by combining the corresponding control algorithm.

As shown in the figure, the system includes seven modules, including master control chip TMS320F28027, drive circuit, switching element, feedback network, off-chip memory for storing system configuration information, data acquisition interface and system extension interface.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 the amount of power grid voltage collected (including data acquisition interface, environmental brightness, system parameters such as temperature) algorithm processing, frequency and duty ratio of PWM signal, then the output PWM signal, the PWM signal after driving circuit amplifier is used to drive the switch element of switch power supply, the system of high brightness LED street lamp power supply,The voltage at both ends of the LED street lamp and the current flowing through the LED street lamp are fed back to the master control chip through the feedback network to correct the control effect.The extended interface provided by the system is used for data interaction with other peripheral modules, so as to facilitate the expansion of the functions of the driver in practical applications. For example, the Zigbee or GPRS modules are mounted through the extended interface to realize the networking management and remote maintenance of the driver.

Program features

High brightness LED driver based on TMS320F28027 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.The high brightness LED driver single-chip solution based on TMS320F28027 has the following characteristics:

Low cost - the single chip solves the multi-channel constant current control, eliminates the special constant current chip, effectively reduces the system cost

High efficiency -- non-isolated switching power supply, no magnetic leakage loss of transformer, high conversion efficiency, the overall efficiency of the system when full load is up to 95%

Strong driving ability -- 8-way non-isolated constant current drive output, can drive 8 strings (no less than 14 leds per string), the total output power is no less than 100W

Flexible control -- high performance DSC is adopted as the control core, which can give full play to the advantages of 32-bit real-time control function. The current size and on-off mode of each LED can be independently controlled

Good expansibility -- reserve temperature, brightness, color temperature and other detection interfaces, support serial port, I2C and other data interfaces, and pave the way for system integration (such as Zigbee networking for LED street lamps, extending GPRS module, etc.)

In addition, the scheme supports 12-bit ADC resolution and 256 step grey scale control.Wide voltage input range, when using additional system power supply, the input voltage can be up to 100V;When the control system and LED series share a DC power supply, it is up to 60V;It supports under-voltage locking and over-voltage protection, over-temperature protection expansion, no-load detection, over-current protection, brightness power off automatic saving, and four-channel group delay noise reduction.


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