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- PostSlew Rate Control Optimisation for Gate Driver Circuit of NPC Multilevel Inverter(2024) Srivastava, Harsh; Ganesh, Subramanian; Chalmers tekniska högskola / Institutionen för elektroteknik; Liu, Yujing; Orbay, Raik; Moabber, Kooros; Mademlis, GeorgiosAbstract Electric Vehicles (EVs) introduce unique challenges in managing Electromagnetic Interference (EMI) due to the coexistence of high and low voltages within confined spaces. At the same time, there is the need for increased efficiency of the propulsion system in order to increase the range of the EV, which means application of high-switching-speed power electronics and the introduction of wide-bandgap technologies. The overarching objective of this study is to attain optimal EMI levels within the EV’s electromagnetic environment by exploring the application of multilevel inverters (MLI) based on wide-bandgap switches and optimized gate driver design with a central focus on better EMI performance and energy efficiency. The proposed approach involves refining switching techniques of Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) to strike a balance between switching rates and EMI generation. Rapid switching, while reducing losses, can lead to increased switching transients and magnetic fields, which contribute to EMI. A pivotal element of this research is the design of a gate driver circuit with controlled slew rates, specifically tailored for The Neutral Point Clamped (NPC) converter. Each switch in the inverter has been prefixed with a custom gate driver as per its slew rate. The investigation commences with a meticulous analysis of a three-level inverter, encompassing diverse driver circuit simulations. Subsequently, the developed gate driver design is implemented in a 3-level inverter configuration. This choice aligns with multilevel inverter principles, enabling efficient operation at higher voltage levels compared to traditional two-level inverters. NPC converter topology, widely embraced in machine drive applications, forms the bedrock for these experiments. To assess the efficacy of the proposed solution, a rigorous evaluation of modulators, including Sinusoidal Pulse Width Modulation (SPWM) and Space Vector Modulation (SVM), is executed through comprehensive simulations. This examination hinges on their capability to curtail EMI across the electromagnetic spectrum. Following assessment of switching techniques, a system level loss distribution analysis is done to map which switches have more concentration of switching losses. Accordingly, a unique gate driver design is proposed for each switch, and improvements in EMI magnitude and switching losses are noted. In sum, this research endeavours to refine EV systems by orchestrating advanced switching techniques and tailored gate driver designs. By doing so, it aspires to bring down EMI to optimal levels and unlock a future of seamless electric mobility.
- PostOver the Air Phased Array Calibration at 100 GHz(2024) Tahan, Dani; Chalmers tekniska högskola / Institutionen för elektroteknik; Eriksson, Thomas; Tabeshnezhad, Azadeh; Wettergren, JohanAbstract This thesis presents a comprehensive analysis of building and calibrating a 100 GHz transceiver with a 10 GHz bandwidth, focusing on component selection based on performance characteristics and incorporating linear phased array antennas of various sizes. The study emphasizes the role of uncertainty sources such as impedance mismatches, temperature fluctuations, and structural errors in antenna performance, analyzing arrays of 4, 8, and 16 elements to understand size effects on antenna behavior and achieve a coverage range of ±60°. Key findings indicate that 4-bit phase shifters can closely replicate theoretical beam patterns with minimal deviation, while amplitude perturbations significantly impact 8-element arrays more than 16-element arrays, with 4-element arrays displaying greater perturbation tolerance. Temperature-induced phase shifts necessitate calibration for the 4-element array at extreme temperatures, whereas 8-element arrays show reduced sensitivity. The thesis further evaluates two calibration algorithms designed to address systematic phase errors caused by manufacturing error, such as bent slab distortion and irregular phase errors. The mREV algorithm required multiple iterations to align the radiation pattern with theoretical predictions, while the simpler ON/OFF method achieved similar results with a single iteration. Notably, the number of iterations needed for the mREV algorithm decreases as the number of array elements increases, enhancing calibration efficiency.
- PostDevelopment of HighWater Content Tissue Phantoms for Quality Assurance in Hyperthermia(2024) Huseyin, Cengizhan; Chalmers tekniska högskola / Institutionen för elektroteknik; Dobsicek Trefna, Hana; De Lazzari, MattiaAbstract As cancer persists as a notable health challenge worldwide, novel therapeutic approaches are required to complement current treatment modalities. Hyperthermia therapy is recognized to be an effective approach, which can be combined with either chemotherapy or radiation therapy in order to effectively treat tumors using electromagnetic radiation to generate heat. Depending on the size, depth and location of the tumor, various heating devices are used for treatment. Radiative microwave and radio-wave systems are commonly used for the treatment of deep-seated tumors in larger anatomical regions, operating within the lower frequency range of 70-120 MHz. To ensure that these devices can deliver adequate heat within the targeted area, adherence to quality assurance guidelines protocols are important. These guidelines are pivotal for maintaining the quality of heating devices as well as protecting the health of individuals receiving treatment. The evaluation of device performance is conducted through the utilization of physical materials known as phantoms. The purpose of using phantoms is to replicate the biological and dielectric properties of tissues in the human body. Depending on the specific tumor being treated, various phantom materials can be used and combined with each other in order to simulate the properties of the tissues where the tumor is located. It is essential for these phantoms to possess sufficient mechanical strength to be able to endure the experimental conditions, as they will be subjected to heat in clinical trials. In this thesis, hydroxyethylcellulose was used as a ground component in conjunction with agar, glycerol and salt to fabricate a mechanically stable phantom that mimics the dielectric properties of muscle tissue, with the aim of treating deep-seated tumors. To achieve a functioning phantom possessing the desired properties, an optimization of the process was performed by analyzing various parameters in regards to concentration, molecular weight and air bubble formation.
- PostEnhancing EV Battery Recycling Through Discharge Optimization(2024) Burman, Adam; Chalmers tekniska högskola / Institutionen för elektroteknik; Zou, Changfu; Yuan, MengAbstract The use of lithium-ion (Li-ion) batteries for electric vehicles (EVs) has increased exponentially and is expected to continue growing with the electrification of transportation. The increased usage of Li-ion batteries poses new challenges for reusing materials and improving the efficiency of battery recycling. Battery modules from electric vehicles that have reached their end of life (EOL) are fully discharged prior to recycling and minimizing discharge time is crucial for the industry. This study evaluates discharge current profiles generated by control strategies based on discharge time and the ability to maintain a safe internal battery temperature. The evaluation is performed using Simulink models of a table-based battery cell and a battery module representing a module in a 12s2p configuration based on the LG Chem E78 battery pouch cell. The controllers tested include constant current constant voltage (CC-CV), constant current constant temperature (CC-CT), dynamic programming (DP), and robust model predictive control (MPC). The results indicate that to avoid violating temperature constraints, controllers using model-based prediction and incorporating real-time measurement data with a Kalman filter, such as robust MPC, achieve the shortest discharge time without violating temperature constraints, showing promise for future applications.
- PostAdaptive Control of Thermal System in Electrified Heavy Vehicles - Investigation in how adaptive parameters used in predictive control can minimize model prediction errors(2024) Andersson, Mats; Chalmers tekniska högskola / Institutionen för elektroteknik; Wik, Torsten; Lindgärde, OlofAbstract The development of battery electrical heavy vehicles is an important factor in reaching climate change goals and increasing the standard of living by reducing emissions and noise pollution. The cooling system serves as a crucial component for keeping parts in their ideal operating window which reduces wear, as well as increases performance. Applying predictive control to these vehicles is another step in improving performance with reduced power consumption and increased life expectancy of components. This work investigates the possibility of applying adaptive parameters to be used in predictive controllers to improve predictive estimates and thus also the control. We use estimation techniques, such as recursive least squares (RLS) and extended Kalman filtering (EKF) to estimate the adaptive parameters that can be fed back to a supervising controller, such as a model predictive controller (MPC). Results show that using adaptive parameters improves predictions with reduced prediction errors. The results indicate the possibility of accuracy improvements that combined with improved control structure could lead to better performance.