The Stability Analysis And Self-diagnosis For DSP Based Phase-Shifted Full-Bridge Converter

Stability is an important performance for control systems, it is also the most important condition for normal operation. The major consideration in design systems is the stability of its closed-loop control. With the development of digital control technology and the widely use of digital power systems, the stability of digital closed-loop control system is gaining more and more attention. Therefore, this thesis studies the stability of digital power system according to the digital control special characteristics.A phase-shifted full-bridge DC/DC converter based on DSP is taken as an example. The design of hardware and software is given in detail, and the selection of control parameters is introduced through Matlab design tools. Because of the zero-order holder and delay-time effect, the stability of digital control system is different compared to the traditional analog ones. The effect of control delay is discussed, and the proportional and integral parameters influence is studied in this thesis. Furthermore, the related experiment is presented to prove the correctness of theoretical analysis. Traditionally, stability testing needs the help of the network analyzer. In order to make good use of digital control resource, this thesis introduces a design scheme of stability self-diagnosis inspired from the idea of"Virtual Instrument", based on Freescale's DSP, an digital stability self-diagnosis solution are designed in detail .