Affiliations: [a] School of Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan 430070, Hubei, China | [b] Institute of Advanced Material Manufacturing Equipment and Technology, Wuhan University of Technology, Wuhan, Hubei 430070, China | [c] Hubei Maglev Engineering Technology Research Center, Wuhan University of Technology, Wuhan, Hubei 430070, China | [d] China Ship Development and Design Center, Wuhan 430070, Hubei, China
Correspondence:
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Corresponding author: Xin Cheng, School of Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan 430070, Hubei, China. Tel.: +86 027 87651793; E-mail: chengx@whut.edu.cn.
Abstract: Power amplifier is a crucial part of the active magnetic bearing system, and its precision characteristic is decisive to the overall systematic performance. The bi-state and tri-state modulations are both widely used in the design of DSPA, and generally there are many approaches to realize the design. DSPA will have different output performance under different modulations. In this paper, we propose a unified design of digital switching power amplifier (DSPA), which can be compatible with different modulations by configuration of hardware only. As many factors will influence the current ripple characteristic of DSPA, an approach based on Fourier series has been proposed to establish the equivalent mathematical model of DSPA under both bi-state and the tri-state modulations. We analyze the approximated theoretical ripple characteristic of DSPA with the unified architecture design discussed, and provide the simulation based on the equivalent mathematical model, then establish the experimental platform to verify the analysis of current ripple characteristic under different conditions. Experimental results show that the ripple characteristic has been influenced mainly by bus voltage, modulation frequency and time constant of load, and the approach proposed in this paper can effectively describe the ripple characteristic of DSPA under different modulations.
Keywords: Current ripple characteristic, unified design, digital switching power amplifier, active magnetic-levitated bearings
