In this study, a power converter topology and control schemes for the power converter stages are proposed for a DC extreme fast charger. The proposed system is composed of a cascaded H-bridge (CHB) converter as the active front end (AFE), and an input series output parallel (ISOP), which includes three parallel connected dual active bridge (DAB) cells. A modified Lyapunov Function (LF) based control strategy is applied to obtain high current control response for the AFE. An additional controller to remove the voltage unbalances among the H-bridges is also presented. Additionally, the triple phase-shift (TPS) control method is applied for the ISOP DAB converter. A Lagrange Multiplier (LM) based optimization study is performed to minimize the RMS current of the transformer. The performance of the proposed converter topology and control strategies is validated with MATLAB/Simulink simulations.
A Control Scheme Based on Lyapunov Function for Cascaded H-Bridge Multilevel Active Rectifiers
The cascaded H-bridge multilevel active rectifier is a prominent converter configuration. It presents compelling advantages, including high adjustability for a number of applications, such as in solid-state transformers, traction applications, medium and high power motor drives and battery chargers. However, when the H-bridge is operating under an unbalanced load and asymmetrical voltage conditions, it becomes important to design advanced control strategies to maintain the stability of the system. In this study, a Lyapunov-function based control method is proposed for controlling the single-phase cascaded H-bridge active rectifier to achieve global asymptotic stability. A capacitor voltage feedback is added to the conventional Lyapunov-function based stabilizing control method to minimize the resonance of the LCL filter. Additionally, a Proportional-Resonant (PR) control approach is adopted to obtain the reference current signal. This increases the robustness of the current control scheme. A DC voltage balancing control procedure is also employed to prevent the unbalanced DC voltage conditions among the H-bridges. The DC voltage is controlled via a PI controller. The capability of the control approach is verified with simulation and experimental studies.
- Award ID(s):
- 1939124
- Publication Date:
- NSF-PAR ID:
- 10221389
- Journal Name:
- 2020 IEEE Applied Power Electronics Conference and Exposition (APEC)
- Page Range or eLocation-ID:
- 2021 to 2026
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Publisher's Version of Record
- https://doi.org/10.1109/APEC39645.2020.9124234
