【摘要】 基于斩波技术原理,采用Buck降压变换方案,设计一种强非线性负载的恒流电源.系统由Buck主电路,辅助电源电路,输出电流信号采集电路和控制电路四部分组成.整个系统由一路交流电源经降压后供电.辅助电源采用宽范围输入的LM2576芯片和三个WRB1215芯片组成;控制电路控制器采用增强型51芯片STC15W4K56S4;电流信号采集电路由0.2欧姆功率电阻取样,经TL082两级运放后以电压信号输入到单片机.针对LED的非线性特性,采用参数自调整PID进行恒流控制.经实际测试,系统输入交流电压可在32~40V范围内变化,输出电流可在150~350mA步进调整,稳态电流误差小于1%,最大动态偏差小于10%.更多还原

【Abstract】 One constant current source used for strong nonlinear load was designed;it′s based on the Buck Chopper.The system mainly consists of four parts:buck circuit,auxiliary power circuit,output current sampling and amplifying circuit and control circuit.LM2575 and WRB1215 chip are used in auxiliary power circuit.LM2575chip′s input voltage can change in large range.Control circuit was designed using STC15W4K56S4 chip.Current source is sampling by 0.2ohm resistance and then it is amplified by two stage amplifier circuit.One parameter self-adjust PID control algorithm is used in control circuit.Testing results shows:input voltage′s change range is form 32 volts to 40volts;output current can be adjusted from150 mA to 350 mA,constant error is under one percent,the largest dynamic error is under ten percent.更多还原