Joselyn Stephane Menye

This paper provides a comprehensive analysis of the lithium battery degradation mechanisms and failure modes. It discusses these issues in a general context and then focuses on various families or material types used in the batteries, particularly in anodes and cathodes. The paper begins with a general overview of lithium batteries and their operations. It explains the fundamental principles of the electrochemical reaction that occurs in a battery, as well as the key components such as the anode, cathode, and electrolyte. The paper explores also the degradation processes and failure modes of lithium batteries. It examines the main factors contributing to these issues, including the operating temperature and current. It highlights the specific degradation mechanisms associated with each type of material, whether it is graphite, silicon, metallic lithium, cobalt, nickel, or manganese oxides used in the electrodes. Some degradations are due to the temperature and the current waveforms. Then, the importance of thermal management and current management is emphasized throughout the paper. It highlights the negative effects of overheating, excessive current, or inappropriate voltage on the stability and lifespan of lithium batteries. It also underscores the significance of battery management systems (BMS) in monitoring and controlling these parameters to minimize the degradation and the risk of failure. This work provides a summary of valuable insight into the development of BMS. It emphasizes the importance of understanding the degradation mechanisms and failure modes specific to different families of lithium batteries, as well as the critical influence of temperature and current quality. Rational management or efficient controlling of these parameters can enhance the performance, reliability, and lifespan of lithium batteries.

Heat pumps (HPs) have become pivotal for heating and cooling applications, serving as sustainable energy solutions. Coupled with renewable energy sources (RES) to run the compressor, which is the major energy-consuming component, they contribute to eco-conscious practices. Notably, their adaptability to be supplied by either alternating (AC) or direct (DC) currents, facilitated through converters, makes them more flexible for versatile renewable energy (RE) applications. This paper presents a comprehensive review of converter topologies employed in various HP applications. The review begins by exploring previous applied photovoltaic (PV)-HP projects, focusing on the gaps in the literature concerning the employed converter topologies. Additionally, the review extends to include a broader examination of the converter topologies that could be employed on the source and load sides of a system powered by a mix of renewable energy sources, such as photovoltaics (PV), wind turbines (WTs), and energy storage systems (ESS), and analyzes their strengths and weaknesses. Special emphasis is given to understanding the various topologies of the power electronics converters in the context of HP applications. Finally, the paper concludes with a summary of the literature gaps, challenges, and directions for future research.

This paper proposes a general design principle of a single-carrier-based pulse width modulation (SC-PWM) technique for a uniform step, asymmetrical multilevel converter with k series-connected H-bridge inverters under unequal DC-link voltages within each phase. The proposed modulation approach is a straightforward implementation of the conventional phase-disposition PWM. It may produce many output voltage levels (any odd number between 2k+1 and 3 ^k ) using only one carrier signal without complicating its implementation scheme. This makes it suitable for real-time implementation in available low-cost microcontrollers and microprocessors. The topological structure of the investigated asymmetrical multilevel converter is presented, and analytical relationships are established to define a general design principle of a uniform step configuration. Then, the proposed method's working principle and its generalized implementation scheme are presented and discussed. The effectiveness of the suggested PWM technique is finally demonstrated by simulation and experimental results for a single-phase, three-cell asymmetric converter operating under unequal DC-link voltages with 7, 11, 13, and 15 voltage levels.

Due to their enhanced performance and absence of carbon emission, electric vehicles (EVs) are attracting much interest worldwide. Properly interfacing energy storage with power converters is crucial for the overall EV drivetrain performance and efficiency. Power converters convert electrical energy between different voltage levels and waveforms from the battery to the motor and vice versa. Variations in control schemes based on pulse width modulation (PWM) techniques directly impact losses and temperature profiles on converter power semiconductors, which are directly related to the reliability of power converters. This paper presents a simplified modeling approach to show how PWM-based control strategies impact power converter losses in EV drivetrains. The investigated drivetrain system consists of a two-level inverter interfacing with a bidirectional current boost chopper and supplying power to a permanent magnet synchronous machine. Based on electrothermal models, the influence of sinusoidal PWM method and space vector PWM method on the power converter losses and thermal stresses in power semiconductors are evaluated and analyzed. A performance comparison of different PWM methods is performed through PLECS software-based numerical simulation results.