Operating temperature and humidity are key factors affecting the performance and lifetime of proton exchange membrane fuel cell (PEMFC) stacks. Aiming at the shortcomings of low control accuracy and poor robustness in existing water and thermal management strategies, a water and thermal management strategy based on the twin-delayed deep deterministic policy gradient (TD3) is proposed. The strategy was based on a water and thermal management system model, which improved the traditional control framework of independent control of the water pump, the radiator, and the cathode humidifier, and achieved synchronous control of temperature and humidity. Taking the water and thermal management of a PEMFC stack with 375 cells as an example, the proposed strategy is compared with the water and thermal management strategy based on the deep deterministic policy gradient (DDPG) through simulation experiments under the mixed driving cycle condition. The maximum deviations of the inlet temperature of the stack and the temperature of the stack from the ideal temperature under the TD3-based strategy are reduced by 0.10 K and 0.07 K, respectively, compared with the maximum deviations under the DDPG-based strategy; the TD3-based strategy maintains the cathode inlet humidity between 25% and 62%, while the DDPG-based strategy maintains the cathode inlet humidity between 0 and 98%. The results show that, compared with the DDPG-based strategy, the proposed strategy performs better, effectively reducing the maximum temperature deviation and the range of humidity changes of the stack.

The receiving end of the hybrid cascaded DC transmission system adopts a series structure composed of a line commutated converter (LCC) and parallel-connected modular multilevel converter (MMC) modules. This special structure has been applied in practical engineering. However, due to the extremely unavoidable first phase change failure of LCCs and the complex electrical characteristic relationship between LCCs and MMCs at the receiving end, the control strategy for suppressing the subsequent phase change failure at the receiving end of the hybrid cascaded DC transmission system has become difficult. To this end, a joint control strategy for suppressing subsequent phase change failure in hybrid cascaded DC transmission systems is proposed, which is to convert the variation of the inverter-side LCC extinction angle into the reactive power issued by the MMC, and to carry out a reasonable reactive power allocation of the MMC, and at the same time, to add a nonlinear voltage dependent current order limiter (VDCOL) control strategy in the LCC to achieve effective suppression of subsequent phase change failures in the hybrid cascaded DC transmission system. A simulation model is constructed in PSCAD to analyze the proposed joint control strategy, and the correctness of the proposed method and its adaptability to multiple faults are verified.

To achieve lightweight and high-efficiency auxiliary power supply systems, a study was conducted on high-voltage and high-power DC-DC conversion power modules tailored for the application scenarios of new energy locomotive auxiliary power supplies. A quasi-two-stage topology was proposed, consisting of an input series output parallel (ISOP) three-level Boost (TL-Boost) and a full-bridge LLC resonant circuit, suitable for high-voltage and high-power applications. The working principle of this topology was detailed, and in response to the issues with traditional proportional integral (PI) control, an active disturbance rejection control (ADRC) method was proposed, addressing the instability of output voltage due to load fluctuations. This ultimately achieved high current sharing and high-stability operation of the auxiliary power supply. A prototype was constructed, comprising two 150 kW TL-Boost+LLC resonant converters, which was validated. The experimental results demonstrated the feasibility and effectiveness of the proposed DC-DC converter and control method, bearing significant engineering implications.

With the digital transformation and development of the petrochemical industry, power quality issues are becoming increasingly serious. Due to production needs, a large number of nonlinear, asymmetric, and impactful power loads are connected to the power grid, resulting in a series of power quality disturbances that affect the safe operation of the petrochemical industry. On this basis, a deep-learning-based method for identifying power quality disturbances in the petrochemical industry is proposed. A multi-scale temporal convolutional network (TCN) is used to extract global and local features of power quality time-series signals, and a multi-head self-attention mechanism is introduced to highlight important features and improve the recognition performance of the model. Based on simulation data and power grid data from a petrochemical industry in a certain region, the experimental results show that the proposed method can achieve high-precision identification of single and composite power quality disturbance signals, and has strong anti-noise and generalization capabilities.

In order to address the problems that sensitivity of traditional single-ended driven wireless power transfer (WPT) systems to positional misalignment and their reliance on detection and control mechanisms, a novel single-ended driven WPT system with misalignment tolerance is proposed. The system is based on a hybrid configuration of unipolar and bipolar coils, maintaining constant coupling magnetic flux under misalignment conditions. By utilizing orthogonal excitation from two sets of single-ended driving circuits and optimizing the parameters of the compensation circuit, the system achieves constant voltage output resistant to positional misalignment without relying on detection and control. Furthermore, the system maintains efficiency without degradation across the entire range of positional misalignment. Simulation and experimental results validate the effectiveness of the proposed anti-misalignment system, demonstrating a constant voltage output with less than 0.77% ripple under [-24.24%, 24.24%] misalignment, while achieving an efficiency of 85.14% with ripple less than 1.96%. This approach not only reduces the number of switching devices and associated driving circuits but also ensures robust offset resistance capabilities.

The single inverter single transmitter multi-frequency and multi-receiver inductive wireless power transfer (WPT) system can simultaneously support multiple loads of different frequencies, with a simple structure and good compatibility, and has great potential for application. Its compensation network requires a large number of passive components, forming a high-order system with complex constraints, and thus the parameter design of high-power and high-efficiency compensation network faces enormous challenges. The dual-frequency LCC-S structure is taken as an example, and the design variables are reduced from seven to only one through analysis. In order to achieve high-power and high-efficiency transmission of the system, a dual-frequency compensation network design method based on differential evolution algorithm and Lagrange multiplier method is proposed, taking into account the influence of inductance parasitic resistances. Finally, an experimental prototype was constructed based on the design scheme obtained by this method. Experimental results demonstrate that the prototype can achieve load independence and constant voltage characteristics without relying on control methods, with a system output power of 165.83 W and a total efficiency of 94.05%.

A single-stage power-controlled wireless power transfer (WPT) system for underwater environments is proposed, in which the output power can be kept constant when the mutual inductance, input frequency, and load change. Compared with the conventional underwater wireless power transfer (UWPT) system, this system can achieve input frequency adaptation and second-side power customization, and has a wider output regulation range, which can enable underwater devices including autonomous underwater vehicle (AUV) to better adapt to different charging conditions. This UWPT system uses an S-S compensation network, but the secondary side is connected in series with a switched-controlled capacitor (SCC). Secondary side frequency following is achieved by controlling the SCC, while the conduction angle of the semi-active rectifier (SAR) is adjusted to reconfigure the equivalent impedance, and then the SCC is further regulated to eliminate the excess capacitive reactance of the secondary side, which ensures the constant current characteristics of the system and thus achieves the output power regulation. The system is defined only by the single-stage power definition of the second-side, which effectively circumvents the underwater wireless communication. The feasibility of the UWPT system as well as the control strategy was finally verified by multi-environmental simulation experiments.

A novel architecture for battery balancing systems based on wireless power transfer (WPT) is proposed to address the challenges of complex external wiring, low integration and poor maintainability. In this system, wireless power transfer coils, batteries, and the balancing control unit are integrated into a single structure. By incorporating relay coils, energy exchange pathways between any two imbalanced units are established. An LCC resonant network is introduced to suppress interference from non-imbalanced units during energy transfer. To overcome efficiency degradation caused by variations in battery load during balancing, a maximum efficiency tracking (MET) control strategy is developed. This strategy employs a semi-active rectifier (SAR) to emulate the optimal load, ensuring the system consistently operates at its maximum efficiency. To verify the feasibility of the proposed system, a six-coil balancing experimental platform is constructed. Experimental results confirm the effectiveness of the proposed architecture and control strategy, demonstrating significantly enhanced energy transfer efficiency during balancing compared with existing WPT-based systems.

To address the lack of systematic performance evaluation methods for unmanned aerial vehicle wireless power transfer (WPT) systems, a comprehensive quantitative evaluation model based on the analytic hierarchy process (AHP) and fuzzy comprehensive evaluation is proposed. The model establishes a hierarchical evaluation framework from three criteria layers: charging energy efficiency, system economy and applicability, as well as reliability and environmental adaptability. These are further subdivided into 13 specific indicators, including transmission efficiency, rated power, unit power cost, maintenance convenience, and environmental adaptability. The weight of each indicator is determined through expert judgment matrices, and a multi-dimensional quantitative analysis of the system is achieved by integrating the fuzzy comprehensive evaluation method. A case study demonstrates that the model can effectively evaluate the performance of systems with different technical approaches, providing a scientific basis for the design optimization and selection decisions of unmanned aerial vehicle wireless power transfer systems.

The high-voltage power supply is a high-voltage and wide-range input power supply, which is used in flexible DC transmission systems to power the modular multilevel converter (MMC) submodule control circuit. In order to make the power supply work under a higher and wider input voltage range, a multi-channel input series structure is used to reduce the voltage stress of power and magnetic devices. In view of the problem of too many magnetic components in the series circuit and whether the input voltage at each level is balanced, a high-voltage power supply based on planar magnetic integrated transformer designed. First, the double-switch flyback topology and its important modes are introduced, and the principle of voltage self-balanced is analyzed. Subsequently, the planar magnetic integrated transformer is specifically designed. Then the planar magnetic integrated transformer is simulated by Maxwell software. The magnetic density distribution, loss and temperature rise characteristics of the transformer are analyzed. Finally, a prototype that can operate stably and effectively with an input voltage of 350.0 V~4 000.0 V and an output voltage of 400 V is built. The experimental results show the effectiveness of the design.