The LightCube mission is a CubeSat whose goal is to allow users to manually flash a light that is observable by the naked eye. LightCube required the design of custom electronics because of its small size and unique mission. The majority of the volume of LightCube was taken up by the payload electronics, precluding any use of most off the shelf CubeSat components. A custom EPS system was designed and developed by students at ASU to meet all the power requirements of LightCube. The satellite’s solar panels were constrained to a 1U size and the batteries were given a limited volume. The EPS was architected with these constraints in mind to optimize for the space given. It consists of a charging circuit, two converters, voltage and current measuring circuits, and a separate battery board which includes a battery fuel gauge, current sensor, inhibit circuitry, temperature sensor, heater, and optional linear battery charger. One of the underlying goals of this design was to make the EPS and battery board as simple as possible. The design was intentionally simple and left out other features such as a microcontroller for ease and speed of development as well as minimize complexity to lower the risk of catastrophic failure due to radiation or other space events.

Switch-mode power converters operate at frequencies ranging from tens to hundreds of kilohertz and tend to generate significant conducted EMI within the regulated frequency band of 0.15-30 MHz. Converters typically require an input filter to comply with electromagnetic compatibility standards to prevent high-frequency currents from traveling through the power source conductors. The traditional EMI filters are usually made of passive components, which are substantial in size, sometimes occupying as much as one-third to one-fourth of the total volume, limiting the power density of the power converters. An alternative to bulky passive EMI filters is the utilization of active electronics, which inject voltages or currents to counteract the interference signal. This work introduces a boost converter in conjunction with a synchronized switch mode Active Electromagnetic Interference Filter (AEF), which reduces energy storage requirements compared to passive EMI filters. The proposed AEF operating at a frequency of 30 MHz effectively mitigates additional EMI into the system as its operational frequency lies beyond the typical range of conducted EMI. The AEF is realized using a synchronous buck converter with a series resonant tank and the current configuration is designed to counteract the ripple component of the boost converter. Firstly, this work presents the comprehensive analytical modeling of the AEF circuit consisting of a series resonant tank to determine the variation of AEF current magnitude to circuit parameters, and duty-controlled switching in the proposed AEF is implemented using high-speed analog circuits to generate pulse width modulated (PWM) signals for the filter. The proposed methodology controls the magnitude of AEF current to a desired value in an open loop to reduce the complexity of the circuit. Further, the AEF is employed in a (6-12)V-to-24V boost converter switching at 150 kHz and has been found to attenuate the fundamental ripple component. From the experimental results, an attenuation of 23dB is achieved using the proposed AEF and a reduction of LC product by a factor of 16 in the AEF and the effective volume of the AEF by 47% compared to that of a single-stage fully passive LC filter.

Power amplifiers and tuneable matching networks for plasma generation systems arebeing continuously advanced, and recent innovations have shown tremendous improvements in their size, efficiency, and capability. These improvements must ultimately be validated on a live plasma chamber, but this is costly and time-consuming, and debugging errors or failures is a challenge owing to the highly dynamic nature of the plasma and the experimental prototype nature of the advancements. This work addresses this challenge by developing a reactive load emulation system that can mimic the inductive reactance of a live plasma chamber. This includes a study of the saturation characteristics of low-permeability, high-frequency materials, demonstration of the suitability of this method for plasma emulation, and the design of an inductor array platform which verifies the approach.

With the emergence of electric transportation and the infrastructure for electric vehicles (EVs), numerous viable approaches and topologies have emerged. In order to improve the power quality of the grid, it is essential for Onboard Battery Chargers (OBC) for electric vehicles to maintain a power factor closer to unity. This study mainly focuses on two prominent PFC topologies, Totem-pole PFC (TPFC) and H-Bridge PFC (HPFC), which are simple to implement and capable enough of providing high operating efficiency. This study elucidates the comprehensive comparison of the TPFC and HPFC converters using the comprehensive mathematical modeling approach, simulation models, and the hardware experiments. Also, the comparison of the EMI filter requirement and design of DM EMI filter for both the topologies is also extensively illustrated in this study. Firstly, focusing the comprehensive mathematical models of TPFC and HPFC converters, which includes the mathematical formation of the duty cycle for both the converters incorporating the discretized input current controller into the mathematical model which gives more closer comparison when it is compared to simulation models and the hardware experiment model operations. The input current FFT analysis and the THD modeling are also covered in the mathematical modeling of TPFC and HPFC converters. Moreover, the EMI noise is modeled, and the corresponding EMI filter is also designed for both the PFC topologies. Further, the simulation models of TPFC and HPFC converters are also developed and the outputs of the simulation models show an input AC current is precisely following the input AC voltage and also the output voltage of constant 400V is attained for both the PFC converters. Similarly, for the experimental results, the constant 400V regulated DC output voltage is obtained and the input AC current is following the input AC voltage with the power factor of 0.983 for TPFC and 0.99 for HPFC converter. Moreover, the implementation of the EMI filter at the front end of the converter succinctly attenuates the EMI noise and complied within the FCC Class A limit for both TPFC and HPFC converters.

DC-DC converters are widely employed to interface one voltage level with another through step-up or step-down operation. In recent years, step-up DC-DC converters have been a key component in harnessing energy through renewable sources by providing an interface to integrate low voltage systems to DC-AC converters or microgrids. They find increasing applications in battery and fuel cell electric vehicles which can benefit from high and variable DC link voltage. It is important to optimize these converters for higher efficiency while achieving high gain and high power density. Non-isolated DC-DC converters are an attractive option due to the reduced complexity of magnetic design, smaller size, and lower cost. However, in these topologies, achieving a very high gain along with high efficiency has been a challenge. This work encompasses different non-isolated high gain DC-DC converters for electric vehicle and renewable energy applications. The converter topologies proposed in this work can easily achieve a conversion ratio above 20 with lower voltage and current stress across devices. For applications requiring wide input or output voltage range, different control schemes, as well as modified converter configurations, are proposed. Moreover, the converter performance is optimized by employing wide band-gap devices-based hardware prototypes. It enables higher switching frequency operation with lower switching losses. In recent times, multiple soft-switching techniques have been introduced which enable higher switching frequency operation by minimizing the switching loss. This work also discusses different soft-switching mechanisms for the high conversion ratio converter and the proposed mechanism improves the converter efficiency significantly while reducing the inductor size. Further, a novel electric vehicle traction architecture with low voltage battery and multi-input high gain DC-DC converter is introduced in this work. The proposed architecture with multiple 48 V battery packs and integrated, multi-input, high conversion ratio DC-DC converters, can reduce the maximum voltage in the vehicle during emergencies to 48 V, mitigate cell balancing issues in battery, and provide a wide variable DC link voltage. The implementation of high conversion ratio converter in multiple configurations for the proposed architecture has been discussed in detail and the proposed converter operation is validated experimentally through a scaled hardware prototype.

Wide-BandGap (WBG) material-based switching devices such as gallium nitride (GaN) High Electron Mobility Transistors (HEMTs) and Silicon Carbide (SiC) Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) are considered very promising and valuable candidates for replacing conventional Silicon (Si) MOSFETs in various industrial high-frequency high-power applications, mainly because of their capabilities of higher switching frequencies with less switching and conduction losses. However, to make the most of their advantages, it is crucial to understand the intrinsic differences between WBG-based and Si-based switching devices and investigate effective means to safely, efficiently, and reliably utilize the WBG devices. Firstly, a comprehensive understanding of traditional Modular Multilevel Converter (MMC) topology is presented. Different novel SubModule (SM) topologies are described in detail. The low frequency SM voltage fluctuation problem is also discussed. Based on the analysis, some novel topologies which manage to damp or eliminate the voltage ripple are illustrated in detail. As demonstrated, simulation results of these proposed topologies verify the theory. Moreover, the hardware design considerations of traditional MMC platform are discussed. Based on these, a 6 kW smart Modular Isolated Multilevel Converter (MIMC) with symmetrical resonant converter based Ripple current elimination channels is delivered and related experimental results further verify the effectiveness of proposed topology. Secondly, the evolution of GaN transistor structure, from classical normally-on device to normally-off GaN, is well-described. As the benefits, channel current capability and drain-source voltage are significantly boosted. However, accompanying the evolution of GaN devices, the dynamic on-resistance issue is one of the urgent problems to be solved since it strongly affects the GaN device current and voltage limit. Unlike traditional methods from the perspective of transistor structure, this report proposes a novel Multi-Level-Voltage-Output gate drive circuit (MVO-GD) aimed at alleviating the dynamic on-resistance issue from engineering point of view. The comparative tests of proposed MVO-GD and the standard 2-level gate driver (STD-GD) are conducted under variable test conditions which may affect dynamic on-resistance, such as drain-source voltage, gate current width, device package temperature and so on. The experimental waveforms and data have been demonstrated and analyzed.