Lighting
Street lighting |
The suggested power MOSFETs for PFC and HB-LLC are the same |
Energy efficiency , a long lifetime , remote control , small form |
proposed before for the related stages of single string case , while |
factor , and extended temperature range ( -40 ° C ) are the main |
for the buck and reverse buck , the 60-100V low-voltage STripFET |
requirements for the LED street lighting market , and usually |
F7 power MOSFETs series can be adopted . As for the output |
require more than 75W . |
diodes , we propose the STPS schottky diodes , the FERD field |
For single string architectures , we often implement the primary |
effect rectifier and the Ultrafast diodes series ( STTH with ≥ |
side regulation costant current ( PSR-CC ) control technique using a |
200V ) in the HB-LLC , buck and reverse buck circuits . For the PFC |
digital approach with a PFC regulator followed by a HB-LC |
stage the same ones reported in the single string case can be |
resonant stage ( fig . 8 ). |
used . |
For both stages ( power and LED control ), ST offers analog and |
digital driving solutions . |
Fig . 8 – Digital single string PSR-CC LED driver
In this case , the LED driver architecture is based on two stages — PFC and HB-LC circuits ( fig . 8 ) and a single digital IC can manage both . For the single digital IC , ST offers the STLUX , a new series of dedicated digital lighting controllers , as well as several STM32 high-performance microcontrollers .
Different power MOSFETs are suggested for each of the two stages :
Ÿ PFC ( boost ): the 600-650Vbr MDmesh M2 series or the 600V MDmesh M2-EP series . Both families have an extremely low Qg and are optimized for light load conditions . The M2- EP is tailored for high fsw .
Ÿ HB-LC : the 500-600Vbr MDmesh DM2 series , the 600Vbr MDmesh M2 series , or the 600V MDmesh M2-EP series . The DM2 series has an improved trr of intrinsic diode and high dV / dt capability .
Concerning output rectification , the 600V ultrafast series STTH 06 is suggested for PFC ( both TM and CCM ), while the STPSC silicon carbide diodes are suggested only for the PFC-CCM . For the HB- LC , the suggested output diodes are the same as the ones reported previously in the commercial single string approach .
The multiple strings power supply architecture consists of a main power supply providing a constant bus voltage and a subsequent multiple strings ( fig . 9 ). Usually the main power stage , consisting of a high power factor correction ( PFC ) stage combined with an LLC resonant converter , provides the constant voltage bus . The subsequent LED strings control is implemented by multiple buck or reverse buck converters .
Fig . 9 – Analog multiple strings architecture based on Combo controller
Fig . 10 – Digital solution
ST ’ s offerings for these two digital ICs are the same ones reported in the single string case , and the STM8 family microcontroller can also be used for the reverse buck of the secondary side .
STEVAL-ILL066V1 100W , digital single-string PSR-CC LED driver
STEVAL-ILL078V1 60V-1A , buck LED driver converter
STEVAL-ILL053V1 130W , analog power supply for LED Driving
Fig . 11 – Main system evaluation boards for street lighting
STEVAL-ILL056V1 48V-3A , buck LED driver converter
The gate drivers suggested for PFC and HB-LLC are the same mentioned in the single string case ; in the reverse buck scenario , the gate drivers mentioned in the commercial digital LED multiple strings management case are appropriate .
A wide array of system evaluation boards for street lighting single and multiple strings are available . Some of these are shown in fig . 11 . Also , the STEVAL-ILL074V1 / V2 ( 60W analog power supply for LED driving ) and STEVAL-ILL077V1 ( 60W digital multiple-string LED driver ) shown in fig . 7 are appropriate for street lighting applications .
The eDesignSuite software tool The eDesignSuite is an easy-to-use , comprehensive software suite ready to help customers define their needs by transforming their application requirements into satisfactory solutions based on the wide range of ST products . The suite includes
ELE Times | 55 | March , 2017