Stability Analysis for On-Off Voltage-Mode Controlled VHF Converter Combining Short-Period and Long-Period Discrete Map Models

Authors：Chen, Shikai; Chen, Yanfeng^*; Zhang, Bo; Qiu, Dongyuan

Source：IEEE Transactions on Circuits and Systems I: Regular Papers , 2023.

DOI：10.1109/TCSI.2023.3343382

• Very high frequency (VHF)
• stability analysis
• discrete map model
• bifurcation
• ON-OFF voltage-mode control

Benefited from harmonics well-defined and easy design of filter, the ON-OFF voltage-mode control strategy suitable for the very-high-frequency (VHF, 30 similar to 300MHz) dc-dc converter has been developed in recent year. However, the potential risk of this control strategy is that unreasonable parameter design will lead to system instability. Moreover, the conventional stability methods are also difficult to adopt in VHF converters due to its feature of high circuit order and many operating modes as well as extremely high switching frequency. Hence, this article proposes a new stability analysis method suitable for VHF converter employing the ON-OFF voltage-mode control strategy. Firstly, the combined characteristic of short-period switching signal and long-period modulation signal is considered, which dividing the VHF converter into short-period open-loop system and long-period closed-loop system. Then, by establishing both system discrete iterative map models, the effect of converter and controller parameters on stability are revealed by using bifurcation diagram and eigenvalue locus as well as Jacobian matrix. As a result, the established system models and stability analysis can obtain the stability boundary and predict the nonlinear behavior, which helps to guide the parameters design to ensure system stability. Finally, experimental results evaluated the correctness of the theoretical analysis.