数控直流电流源设计 毕业设计.doc

摘 要 随着单片机技术的不断发展和D/A，A/D技术的不断成熟使得数控电源成为可能，数控电流源不论是在控制精度还是在可操作性上都有传统电源无法比拟的优势。本文在参考传统电流源以及普通数控电流源的基础上，在充分考虑性价比的同时极大地提高了数控电流源的准确性，通过软件修正以后在使用普通元件的情况下数控电流源的性能也达到了比较高的水平。系统以直流电流源为核心，AT89C52单片机为主控制器，通过键盘来设置直流电源的输出电流，设置步进等级可达1mA，并可由数码管显示电流设定值。本系统由单片机程控输出数字信号，经过D/A转换器（DA0832）输出模拟量，再经过运算放大器隔离放大，控制输出功率管的基极，随着功率管基极电压的变化而输出不同的电流。实际测试结果表明，本系统输出电流稳定，不随负载和环境温度变化，并具有很高的精度，输出电流误差范围±5mA，输出电流可在1mA~2000mA范围内任意设定，因而可实际应用于需要高稳定度小功率恒流源的领域。 关键词：高精度； DAC0832；D/A转换；恒流源； 软件修正 Abstract Along with single slice machine technical of develop continuously with the D/A, the A/D is technical continuously the maturity make the number control power supply to make possible, count to control the electric current source and is control accuracy in spite of still on the maneuverability all there is traditional power supply cant compare to of advantage. This text in making reference to the foundation that the traditional electric current source and common number control the electric current source, at the full consideration price compare of in the meantime raised a number to control the accuracy of the electric current source biggest, pass the software correction hereafter while use the circumstance of the common component the number controls the electric current source of the function also comes to a higher level. For the system that DC source is center and 89C52 version single chip microcomputer (SCM) is main controller, output current of DC power can be set by a keyboard which step level of 1mA can be available, set value can be displayed by LED. In the system, the digital programmable signal from SCM is converted to analog value by DAC (DA0832), then the analog value that is isolated and amplified by operational amplifiers, is sent to the base electrode of power transistor, so an adjustable output current can be available with the base electrode voltage of power transistor. The test results have showed that the system can output a stable current, which has no influence with load and