Implementation of highprecision current sampling for highperformance permanent magnet AC servo system

HU Dongxuan, SHI Weimin, LU Wenqi, LIU Hu, WANG Wei

(School of Mechanical and Automatic Control, Zhejiang SciTech University, Hangzhou 310018, China)

Abstract: Precision of the whole system is affected by the precision of current sampling which is the important feedback link of AC servo system. In order to improve the precision of current sampling, the high precision current sampling hardware circuit was designed and debugged,then software which used VHDL language to control AD7655 based on complex programmable logic device(CPLD) was designed,software simulation in Lattice Diamond software environment was established. Finally, current sampling experiment was tested. The data wave of current sampling was displayed to observe current sampling result directly. Comparing the accuracy of the sampled data and convert data, the experimental results show that current sampling error is less than 0.7%. The results indicate that this method can implement high precision AC servo system current sampling.

Key words: premanent magnet AC servo system; current sampling; AD7655; complex programmable logic device(CPLD); VHDL language