- The paper proposes an observer-based higher order sliding mode control to achieve unity power factor in three-phase AC/DC converters for hybrid electric vehicles.
- A super-twisting sliding mode observer estimates unmeasured parameters like input currents and load resistance from output voltage, reducing sensor needs.
- Simulation results show the proposed method outperforms PI control, demonstrating robustness to parameter variations and improved output voltage regulation.
Observer-Based Higher Order Sliding Mode Control in Three-Phase AC/DC Converters for Hybrid Electric Vehicles
In "Observer-Based Higher Order Sliding Mode Control of Unity Power Factor in Three-Phase AC/DC Converter for Hybrid Electric Vehicle Applications," Jianxing Liu, Salah Laghrouche, and Maxime Wack propose a control solution for improving power factor correction in three-phase AC/DC converters pertinent to hybrid electric vehicles (HEVs). The paper discusses a robust control method utilizing higher order sliding mode techniques combined with observer-based methods to estimate parameters from partially measured system variables.
The paper focuses on challenges in power conversion efficiency in HEVs, given the complex energy conversion cycles from electric utilities to mechanical power at the drive axle. The researchers present an observer-based controller specifically designed to work with AC/DC converters, which are essential in charging batteries and super-capacitors in HEVs, aiming for a unity power factor to optimize energy transfer from the electrical utility.
Technical Contributions and Methods
The researchers leverage a full-bridge boost power converter to enable power factor control through output higher order sliding mode control. A super-twisting sliding mode observer is integral to this approach, allowing the estimation of unmeasured parameters such as input currents and load resistance from the measurement of output voltage alone. This strategy reduces the dependency on numerous sensors that are potentially noise-prone and increase system complexity and cost.
The authors rigorously demonstrate the robustness and effectiveness of their controller using Lyapunov-based methods, ensuring asymptotic convergence of the closed-loop system to zero. The mathematical model of the system is presented in both phase coordinate and rotating (d,q) frame to derive control strategies that simplify the tracking of desired current profiles and regulation of output voltage levels.
Numerical Results and Evaluation
Simulation results are pivotal in validating the control approach compared to traditional methods like PI controllers. The proposed sliding mode control exhibits superior performance, maintaining a power factor close to unity and demonstrating resilience to parameter variability, such as load resistance and source frequency changes. The simulation indicates that the super-twisting sliding mode control offers reduced overshoot and ripple in output voltage regulation, a key consideration in power conversion applications.
Implications and Future Directions
The practical implications of this research are significant in the context of improving HEV charging systems. The reduced reliance on physical sensors enhances the reliability and cost-efficiency of power conversion systems, and the robust control strategy ensures optimal energy transfer which is critical for achieving desired driving ranges and efficiency in HEVs.
Theoretically, the findings contribute to the existing body of knowledge in nonlinear control methods for power electronics, specifically highlighting the applicability of sliding mode control (SMC) techniques in real-world engineering applications. Future research may extend to integrating such control strategies with adaptive systems that can dynamically respond to varying utility conditions and load demands, further advancing HEV power management technologies.
The research illuminates promising avenues for enhancing power conversion systems in electric vehicles, with application potential extending to broader industrial domains requiring efficient and robust energy conversion solutions.