The flow field plays a significant role in the performance of proton exchange membrane (PEM) fuel cells. However, its complex structure leads to unacceptable development costs and time commonly using the trial-and-error method based on many experiments. Herein, we propose a digitally-assisted method to accelerate the development process and reduce costs. Comprehensive experiments and tests are conducted using the commercial-size PEM fuel cell with an active area of 332 cm², including the investigation of polarization curves, five sensitivity parameters under seven different current densities, and spatial distributions. A high-resolution printed circuit board with 408 segments of 0.8 cm² is employed to explore the current density distribution. The commercial-size PEM fuel cell is further digitalized with a self-developed fuel cell numerical model, which is strictly verified in terms of all experimental data. The digital multi-physics information inside PEM fuel cells is obtained and evaluated via this efficient numerical model in order to search for the structure defects quickly and accurately. Afterwards, targeted structure optimization is effectively carried out to achieve a better performance, with the maximum deviation of oxygen concentration in the channels decreasing from 26.33% to 3.78%. This digital method is very valuable for the forward design of flow field structures to considerably reduce the development cost and time.

With the development of high-frequency, miniaturized, and lightweight power electronic devices, third-generation semiconductor devices are more and more used in the main circuits of power electronic converters. The electromagnetic interference (EMI) generated by their fast switching can affect the performance of power electronic converters. Therefore, it is necessary to investigate the modeling and suppression methods of conducted noise in power electronic converters of third-generation semiconductor devices. This paper describes the EMI sources and coupling paths of EMI in third-generation semiconductor devices used in power electronic converters. The modeling methods of EMI are summarized from the perspectives of power devices and coupling paths. The suppression methods of conducted noise are summarized by suppressing EMI sources and improving coupling path characteristics. This paper provides a reference for the electromagnetic compatibility design of power electronic converters for third-generation semiconductor devices.

The friction and wear response of hard coatings is complex, which largely depends on a good combination of hardness and toughness, and their service life is difficult to predict. Hence, in this work, hard yet tough TiN coatings were deposited using high-power impulse magnetron sputtering at 5–10 kW. With increasing sputtering power, the coatings showed a transition in crystal texture from (200) to (111), along with a refinement in microstructure, leading to an improvement in hardness (H) of 29.8–31.2 GPa and an effective Young’s modulus (E*) of 310–365 GPa. The hard yet tough TiN coatings deposited at 6.5 kW exhibited the highest H/E* and H³/E*² ratios of 0.097 and 0.29, respectively, as well as the highest fracture toughness of 2.1 MPa·m^1/2 and elastic recovery of 42.5%. Accordingly, the coatings possessed an enhanced adhesion and cohesion, in terms of micro-scratch critical load (L_C3 = 19.67 N) and HF Rockwell HF1 level. The friction and wear response of hard yet tough TiN coatings under the normal load of 1–10 N were investigated to explore their durability and predict their critical load up to failure. Wear mechanisms changed from oxidative to severe abrasive wear, with load increasing from 1 to 10 N. At 2–5 N, a combination of oxidative and abrasive wear was observed. The coatings maintained their integrity up to the critical load of 9.4 N before failure event, with a maximum wear track depth of 1.8 μm, indicating their durability under the loading conditions.

Functional safety is an emerging trend for safety design in the automobile industry. This study is an innovative exploration of a hazard analysis and quantitative risk assessment (QRA) methodology based on the functional safety of vehicular fuel cell systems. In this study, the potential hazards that fuel cell vehicles may encounter during operation were identified using the automobile generic hazard list. The failure modes and influences of the main components of the fuel cell system were determined via hazard and operability studies. Furthermore, the risks and consequences of the fuel cell system were explored using the QRA method. The failure frequency and unavailability of the fuel-cell system were calculated, and the architecture was optimized using a redundant design with a focus on hydrogen safety. The results showed that the optimized system architecture could effectively reduce the hazard of hydrogen leakage, and the unavailability and failure frequency of hydrogen leakage risk were reduced by 94.4 % and 36.8 %, respectively. Thus, this study provides powerful insights for future research and improvement of vehicular fuel cell systems.

Fuel cell air supply system has a delay due to compressor during load-changing process, and cannot supply air to the stack quickly, which may lead to oxygen starvation. Oxygen starvation not only affects the output power of the fuel cell, but also leads to a decrease in catalyst performance and fuel cell durability. This paper proposes an adaptive PID controller strategy based on fuzzy logic control for fuel cell air supply system. The control objective is to adjust the oxygen excess ratio to a suitable value to prevent oxygen starvation. The simulation results show that the proposed controller can quickly and stably adjust the oxygen excess ratio to the suitable value.