高精度数控直流电压源的双闭环控制系统设计

摘要

In order to improve the performance of DC voltage source control system and consider the price of the product,a double closed-loop control system of high precision NC DC voltage source with "digital outer loop + analog inner loop" is designed.The outer loop digital control loop is composed of micro-controller and AD / DA and other devices.The fuzzy control is used to realize the rapid adjustment and stabilization of the output voltage fluctuations caused by the external disturbances.To adjust the output voltage accuracy,proportional-integral controller is used by the analog inner loop circuit and the second order low-pass filter is added to the forward channel and feedback channel.Compared with the commonly used single closed-loop control system,its anti-dynamic interference ability has significantly improved.Test results show that the DC voltage source with double closed-loop control system has output voltage accuracy of ± 0.01％,stability of ± 0.003％,ripple of less than 3 mV,and output voltage range of 0 ～ 500 V,which is more cost-effective than similar products at home and abroad.%为了提高直流电压源控制系统的性能,同时考虑产品价格,设计了一套结构为“数字外环+模拟内环”的高精度数控直流电压源双闭环控制系统.其外环数字控制回路由微控制器与AD/DA等器件构成,利用模糊控制实现因外部扰动引起输出电压波动的快速调节稳定;内环模拟电路采用比例-积分控制器,前向通道与反馈通道上添加二阶低通滤波器,以调节输出电压精度.与常用单闭环控制系统相比,其抗动态干扰能力有明显的提升.测试表明:采用双闭环控制系统的直流电压源输出电压范围为0～500 V,稳定度为±0.003％,纹波小于3 mV,精度为±0.01％,与国内外同类产品相比性价比高.