Lithium-ion battery refers to a complex nonlinear system. Real-time diagnosis and accurate prediction of battery state of charge(SOC) parameters are hotspots and critical issues in battery research. To reduce the dependence of state of charge prediction on battery model accuracy and speed, and achieve real-time online estimation, a SOC prediction model of lithium-ion battery system is developed based on the model of support vector machine (SVM). SVM parameter is optimized using an algorithm of particle swarm optimization, and the performance of prediction model is assessed using cross-validation. The obtained experimental data is simulated, involving the comparison with the support vector machine model, and the prediction simulation of the battery in the state of fault. The results reveal that this model with a better performance than that of the support vector machine exhibits high accuracy and generalization ability.

With the rapid development of the electric vehicle (EV) industry, charging facilities for electric vehicles are gradually improving, thus meeting the demand for fast and safe charging. This paper comprehensively describes the current development status and future development trend of EVs and their charging infrastructure and analyzes in detail the EV fast-charging system architecture according to the AC/DC coupling configuration. The topologies and control techniques of the front AC/DC converter and rear DC/DC converter for the charging system are discussed, providing a reference for the future design of hundred-kilowatt level and above fast-charging systems for EVs. In addition, this paper summarizes the EV charging interface and the charging specifications applicable to the hundred-kilowatt power fast-charging system, as well as the impact of fast charging on power batteries, and emphasizes that high-power fast-charging technology is an inevitable trend for the future development of electric vehicles.

Based on current research into the mathematical model of the permanent magnet synchronous motor (PMSM) and the feedback linearization theory, a control strategy established upon feedback linearization is proposed. The Lie differential operation is performed on the output variable to obtain the state feedback of the nonlinear system, and the dynamic characteristics of the original system are transformed into linear dynamic characteristics. A current controller based on the input–output feedback linearization algorithm is designed to realize the input–output linearization control of the PMSM. The current controller decouples the d–q axis current from the flux linkage information of the motor and outputs a control voltage. When the motor speed reaches above the base speed, the field-forward and straight-axis current components are newly distributed to achieve field weakening control, which can realize the smooth transition between the constant torque region and weak magnetic region. Simulation and experimental results show the feasibility and viability of the strategy.

Based on current research into the vector control principles of the permanent magnet synchronous motor (PMSM), a control strategy founded upon an Active Disturbances Rejection Controller (ADRC) is proposed. This control strategy consists of an ADRC speed loop and current controller. By studying the factors affecting the running state of a PMSM, a mathematical model is established, and the design principle of the active disturbances rejection controller is analyzed in order to design the ADRC speed loop. The speed loop considers errors caused by uncertain factors, such as external disturbances, to be the disturbance amount, which is observed and then compensated for by the ADRC, thereby improving the dynamic and static performance as well as the anti-disturbance capability of the system. In order to achieve the strong coupling of the PMSM, the current controller was also designed to decouple the d–q axis current. Our simulation and experimental results demonstrate the feasibility and practicability of this control strategy.

During the power transmission of doubly-fed induction generator (DFIG), due to the influence of series compensating capacitance and long-distance transmission, DFIG is prone to sub-synchronous oscillation, which damages the stability of the system. By establishing the mathematical model of DFIG system, the cause of sub-synchronous oscillation and its influence on the control strategy of DFIG system are discussed. In order to solve the problem of performance degradation of traditional phase-locked loop (PLL) under sub-synchronous oscillation, an improved PLL is proposed to replace the traditional PLL. Aiming at the problem that the control of rotor side converter(RSC) and grid side converter(GSC) in doubly-fed wind power generation system under sub-synchronous oscillation is disturbed by harmonic signals, a control method of adding a quasi resonant controller in the control link of RSC and GSC to suppress sub-synchronous oscillation is proposed, and the feasibility of the method is verified by simulation and experiment. Finally, based on the research process of RSC direct resonance control, the sub-synchronous oscillation suppression strategy based on harmonic current extraction is proposed for the frequency adaptability of the quasi resonant controller. The actual performance of the sub-synchronous oscillation suppression strategy is verified through simulation and experiment. The experimental results show that the strategy is effective.

This paper presents a wide input voltage vehicle DC/DC converter based on an LLC resonant converter for a 48 V light hybrid power system. According to the design requirements of on-board DC/DC converters and an analysis of their system characteristics, a full-bridge LLC resonant converter is employed with a zero-voltage activation of the switching transistors through resonant elements. In terms of the control strategy, the unsatisfactory high-frequency regulation gain of an LLC resonant converter is analyzed under the frequency modulation (FM) control strategy. In addition, to accommodate wide input voltage operating conditions, a composite control strategy is proposed by combining the advantages of the frequency modulation control strategy and phase shift control strategy, analyzing their control principles, and discussing the selection of the control mode switching point. By modeling LLC resonant converters with simulation software, the obtained results verify the effectiveness of the composite control strategy for LLC resonant converters. An experimental platform based on the TMS320F28335 controller, which can achieve stable operation with an input voltage in the range of 300 V–600 V and an output voltage of 48 V, is then built. The experimental results verify the feasibility of the design.