Publications

Given the unpredictable nature of renewable energy injection, a combination of second-life batteries and three-phase electric springs (ESs) is utilized to stabilize the bus voltage from the load side. Voltage stability for critical loads is achieved through the use of a voltage feedback-based reactive power regulation strategy, which makes effective use of the limited output current provided by the second-life batteries. In addition, a consensus algorithm is introduced to facilitate information sharing among multiple ESs, thereby ensuring voltage consensus and restoration. However, the consensus controller is exposed to the risk of false data injection (FDI) attacks, which could lead to voltage fluctuations in the converters. To address this issue, a distributed high-order differentiator (DHOD) is proposed, characterized by its fast response speed and high estimation accuracy, to detect and eliminate attack signals. Through both simulation and experimental validation, it is demonstrated that the proposed strategy enhances voltage stability and energy throughput, even when subjected to FDI attacks.

This article proposes a three-layer framework for autonomous driving systems with optimized trajectory generation and tracking, ensuring optimal energy efficiency during the whole process. The third-order minimize curvature method is built in the first layer, which generates the personalized reference path by smoothing the human driving path to reduce its curvature. The energy-efficient strategy in the second layer is mainly through adopting the motor efficiency map to achieve the best efficiency interval of the operation motor's speed and acceleration, resulting in an optimized trajectory with motor efficiency consideration (OTHDM). The third layer integrates the OTHDM with the model predictive control module built based on vehicle dynamics to generate the optimal steering angle and achieve accurate tracking. The performance is validated through detailed numerical analysis and real human driving data collected by Honda Research Institute, including dozens of different driving scenarios and 19 343 tracks. Various test environments have been established in CarMaker. The experimental results indicate that our method can ensure low energy cost without energy recovery and battery hardware control in various scenarios. The energy saving rate can reach about 5%, up to more than 7%.

In this article, an energy-efficient autonomous driving framework combining adaptive soft actor-critic (ASAC) evaluation reinforcement learning (RL), and model predictive control (MPC) strategies is proposed. It enables autonomous vehicles (AVs) to obstacle-freely track the desired path that the improved A ∗ -based path planner generated. As the core work is to maintain energy-efficient performance, the motor efficiency map is employed to help reduce energy consumption quickly and accurately in an MPC-based predictive path generator and the ASAC-based path-tracking modules. At the same time, the final control input is adapted to the vehicle kinematics, and the generalization performance of the frame is improved. In this work, the CarMaker tool trains and tests on a map of multiple scenarios. Experimental results show that the proposed method is superior to other control methods in path tracking performance, running time, and energy efficiency. Compared to human driving data, this ASAC method can reduce the energy consumption of AVs by 9.432% without any energy feedback mechanism. The method can also deal with various disturbances, such as complex road conditions and vehicle mass changes, and track the path accurately.

This article investigates a novel magnetic power distribution (MPD) system that utilizes conductive magnetic power transfer and wireless power transfer methods. The proposed system employs U- and I-type magnetic cores to form a single-input and multiple-output system, where the U-type magnetic core serves as the transmitter or receiver, and the I-type magnetic core acts as the flux conduction path. By inserting low relative permeability (LRP) I cores between two high relative permeability (HRP) I cores and placing additional U magnetic cores in parallel with the LRP I cores, multiple outputs with different power ratings can therefore be realized. Analysis of operating frequency and the effect of LRP I core on power distribution is presented in detail through theory and simulation. Finally, a prototype with a wide range output power of 200W-550W is tested to evaluate the performance of the proposed MPD system with one- and two-receiver modes, in which the system with a single receiver achieves 329W with a system efficiency of 82.77%, while the system with two receivers obtained a total output power of 422.73W with 86.98% system efficiency.

In this article, a current-source converter based on resonant switched-inductor (SI) unit is presented. By integrating multiple resonant SI units, the proposed SI power converter (SIPC) can realize multiple current conversion ratios. Therefore, the proposed converter is suitable for current conversion applications, especially in high-current and low-voltage applications such as the wireless charging of automated guided vehicles (AGVs). By forming a resonant SI unit, the proposed SIPC can operate with zero-voltage switching (ZVS) over the full range of load, which is beneficial for increasing switching frequency, leading to a more compact topology. The theoretical analysis, high conversion ratio SIPC extension, and design considerations are given in detail. Finally, the feasibility of the proposed SIPC including two- and three-times topologies are experimentally tested over a wide range of output power from 80 to 580 W, where two-times topology achieves a maximum efficiency of 95.72% and three-times topology obtains a maximum efficiency 92.91%.

A magnetohydrodynamic (MHD) engine is a propulsion system that converts electric energy into fluid flow by utilizing the Lorentz force. It has the potential to electrify the conventional rotational propellers on ships, which can have adverse effects on the underwater environment. However, the development of an MHD engine for maritime propulsion is sparse, from the motion theory to the prototype investigation. In this article, the advantage of high-frequency ac operation is depicted. The systematic introduction for the ac MHD engine is elucidated for the electromagnetic field generator configurations, engine drive topologies, and onboard compartment distributions. The propulsion mechanism will be interpreted in force analysis, regarding the Lorentz force and its interaction with the fluid by applying the Stokes law, by deriving the forces to a single ion to the liquid dragged by the engine. Moreover, it provides a case study of the practical development for the engine, showing the power circuit with the forward/reverse control, the analysis of the reluctance circuit and magnetic simulation for the magnetic field estimation, and the laboratory testing solution for mock seawater. A 250-W experiment combining the electric and fluid measurements was conducted to benchmark the ac operational MHD engine structure, validating the proposed topology with practical control and presenting 80% accuracy of the propulsion mechanism analysis.

Ultrasonic testing has emerged as a crucial non-invasive method for monitoring battery health, particularly for accurate State-of-Charge (SoC) estimation in Battery Management Systems (BMS). Unlike invasive methods relying on real-time collection of battery current and voltage, ultrasonic inspection offers timely feedback without interfering with battery properties. However, challenges remain in accurately estimating SoC during rechargeable battery discharging due to ultrasonic echo interference. This study presents an ultrasound-based in-situ rechargeable battery health monitoring system, incorporating advanced signal processing techniques. The proposed Ultrasonic Signal Empirical Mode Decomposition-Extended Kalman Filtering (USED-EKF) algorithm, based on Biot's theory, achieves real-time SoC estimation with exceptional accuracy (maximum error 0.63 %). Compared to conventional EKF, USED-EKF outperforms with significantly lower errors under constant current conditions. Additionally, our model enables the detection of overcharged batteries using ultrasound echo for the first time. This research demonstrates the potential of ultrasonic testing in cost-effective battery maintenance and explosion prevention, contributing to advancements in battery monitoring and safety measures. This research showcases the potential of ultrasonic testing as a cost-effective tool for battery maintenance and the prevention of battery explosions. The achieved results position our study as a pivotal driver in expediting these critical processes, highlighting the significance of our proposed model in advancing battery monitoring and safety measures

This article presents a novel approach that combines Kalman filtering and model predictive control (MPC) algorithms to achieve stable output in a multioutput wireless power transfer (WPT) system for automated guided vehicles (AGVs). Traditional WPT systems often struggle to maintain stable output under varying load conditions and environmental disturbances, impacting the efficiency and reliability of AGV operations. To address this issue, we introduce a Kalman filter for real-time state estimation, coupled with an MPC algorithm for system prediction and control, thereby enhancing the system's robustness and dynamic response performance. Simulation and experimental results validate the superior performance of the proposed method under various operating conditions, demonstrating significant anti-interference capability and stable output characteristics. The results indicate that this method can markedly improve the stability and reliability of the AGV WPT system, providing strong technical support for its practical application.

The new frontier maritime magnetohydrodynamic (MHD) engine drive generates the fields of magnetic and electric to accelerate seawater inside the engine duct. The dc system is overwhelmed by the ac for no explosive and poison gases emission. The proposed power circuit applies a transformer to provide a new drive design for the ac system, by reallocating the field generation currents for propulsion. The excitation current for magnetic field generation now is higher in the primary side of transformer and thus to decrease the current flowing the liquid that drew plenty of the conduction loss in previous ac MHD drive in series-resonant design. To conduct the high-frequency ac to mitigate the gas emission and the phase difference between the fields, three resonant tanks are deployed, constructing a resonant circuit for high circuitry efficiency operation. This article starts from introducing the concept of maritime MHD engine and the research fundamental. The comparison to the conventional ac MHD engine drive stresses its advantage. A steady-state analysis elaborates that the proposed topology and design consideration highlights the optimal design to the turn ratio and engine duct design. The electrical-fluid experiment and the concept verified converter will be demonstrated with the 82% converter efficiency at 470 W, maximum 92% efficiency to back the validity.

The Magnetohydrodynamic (MHD) thruster is an electrical propulsion system that utilizes Lorentz force to convert the electric power to mechanical, accelerating the conductive fluid without the need for conventional moving propellers. However, most propulsion analyses of MHD thrusters are based on fluid dynamics, which is not of the electrical engineering discipline. This article proposes a novel modeling approach that combines Lorentz force with Stokes law in fluid mechanics to figure out the operation mechanism of the MHD thruster. The study investigates the propulsion force towards charged particles in a vacuum and conductive solutions under DC and AC, displaying the resulting moving profiles. Furthermore, this article presents a 550 mm long MHD thruster prototype design that includes the testing liquid solution, electromagnetic field generation, and the power electronic circuit for the electric thruster propulsion, to provide convincing validation of the proposed modeling.