Self-sensing active magnetic bearing using real-time duty cycle

作     者：Ming TANG Chang-sheng ZHU Jie YU 

作者机构：State Grid Sichuan Electric Power Research Institute College of Electrical EngineeringZhejiang University 

出 版 物：《Journal of Zhejiang University-Science C(Computers and Electronics)》 (浙江大学学报C辑（计算机与电子（英文版）)

年 卷 期：2013年第14卷第8期

页      面：600-611页

核心收录：

学科分类：080804[工学-电力电子与电力传动] 080805[工学-电工理论与新技术] 0808[工学-电气工程] 08[工学] 

基　　金：Project (No. LZ13E070001) supported by the Natural Science Foundation of Zhejiang Province  China 

主　　题：Self-sensing Active magnetic bearing (AMB) Frequency spectrum characteristic 

摘      要：In a self-sensing active magnetic bearing (AMB) system driven by pulse width modulation (PWM) switching power amplifiers, the rotor position information can be extracted from coil current and voltage signals by a specific signal demodulation process. In this study, to reduce the complexity of hardware, the coil voltage signal was not filtered but measured in the form of a duty cycle by the eCAP port of DSP (TMS320F28335). A mathematical model was established to provide the relationship between rotor position, current ripple, and duty cycle. Theoretical analysis of the amplitude-frequency characteristic of the coil current at the switching frequency was presented using Fourier series, Jacobi-Anger identity, and Bessel function. Experimental results showed that the time-varying duty cycle causes infinite side frequencies around the switching frequency. The side frequency interval depends on the varying frequency of the duty cycle. Rotor position can be calculated by measuring the duty cycle and demodulating the coil current ripple. With this self-sensing strategy, the rotor system supported by AMBs can steadily rotate at a speed of 3000 r/min.