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一种基于红蓝光亮可调的LED植物光源系统,由直流稳压电路、PIC6F505单片机、基于BCR321U单片机的红蓝LED的驱动电路组成;其特征在于:所述PIC16F505单片机产生的两个PWM矩形脉冲信号去控制BCR321U芯片;再由此去改变红蓝LED的驱动电流以及功率,以此来改变红蓝LED的光亮度;设PIC16F505输出的PWM矩形脉冲为<img file="dest_path_image001.GIF" wi="31" he="23" />,即BCR321U的输入脉冲为<img file="96447dest_path_image001.GIF" wi="31" he="23" />,经过BCR321U内部的RC充放电路后的电压为<img file="dest_path_image002.GIF" wi="34" he="23" />:由<img file="dest_path_image003.GIF" wi="126" he="81" />引入符号<img file="dest_path_image004.GIF" wi="57" he="42" />,得到矩形脉冲<img file="702003dest_path_image001.GIF" wi="31" he="23" />的傅里叶变换式为:<img file="dest_path_image005.GIF" wi="380" he="124" />由<img file="dest_path_image006.GIF" wi="161" he="23" />所以得到<img file="419423dest_path_image003.GIF" wi="126" he="81" /><img file="dest_path_image007.GIF" wi="452" he="124" />其中<img file="dest_path_image008.GIF" wi="232" he="103" /><img file="dest_path_image009.GIF" wi="173" he="47" /><img file="dest_path_image010.GIF" wi="152" he="42" /><img file="dest_path_image011.GIF" wi="211" he="49" /><img file="dest_path_image012.GIF" wi="193" he="42" />为了进行逆变换以求得<img file="630612dest_path_image002.GIF" wi="34" he="23" />,把<img file="dest_path_image013.GIF" wi="49" he="23" />表达式写作<img file="dest_path_image014.GIF" wi="202" he="44" /><img file="dest_path_image015.GIF" wi="187" he="49" /><img file="dest_path_image016.GIF" wi="222" he="44" />则得到:<img file="dest_path_image017.GIF" wi="460" he="34" /><img file="dest_path_image018.GIF" wi="394" he="40" />红光LED和蓝光LED得到的电流分别为<img file="dest_path_image019.GIF" wi="46" he="49" />和<img file="dest_path_image020.GIF" wi="51" he="48" />,红光LED和蓝光LED的输入功率分别为<img file="dest_path_image021.GIF" wi="28" he="24" />和<img file="dest_path_image022.GIF" wi="30" he="24" />,则:<img file="dest_path_image023.GIF" wi="165" he="51" /><img file="dest_path_image024.GIF" wi="170" he="51" /><img file="dest_path_image025.GIF" wi="228" he="60" /><img file="dest_path_image026.GIF" wi="240" he="63" />式中<img file="dest_path_image027.GIF" wi="17" he="19" />为增益电路的增益系数,<img file="dest_path_image028.GIF" wi="17" he="23" />、<img file="dest_path_image029.GIF" wi="19" he="23" />分别为控制红光LED驱动和蓝光LED驱动的BCR321U集成芯片中双向可控硅的导通角,T为RC的时间系数,R为等效电阻,<img file="dest_path_image030.GIF" wi="36" he="24" />是<img file="258033dest_path_image002.GIF" wi="34" he="23" />的峰值。 |