Gallium Nitride Converters for Spacecraft Applications

This work presents the development and evaluation of several Point-of-Load (PoL) Gallium Nitride (GaN) high electron mobility transistors (HEMTs) based synchronous buck converters for computational loads in small spacecraft applications. Design modifications to existing controllers and PCB layout is discussed to maximize the benefits of GaN for these converters. The radiation performance of these converters and in-situ measurements is presented. This work also presents the development of a modular power system architecture for 1U CubeSat compute boards including the electrical and grounding layout, mechanical interface, and size layout. The PoL converter is based on the synchronous buck topology utilizing the Linear Technologies LTC3833 and the Texas Instruments LM25141-Q1 controllers and the EPC 2014C, EPC 2015C, Teledyne TDG100E15B, and GaN Systems GS61004B GaN HEMTs. GaN devices are not only attractive to power electronics engineers in general due to their wide bandgap, low gate capacitance, and low on resistance they also show very promising performance in high radiation environments without the need for expensive radiation-hardened design. Several converters utilizing both commercial-off-the-shelf products and radiation hardened devices were developed and compared to the GaN converters to allow for a comparison between all devices to evaluate the performance of these new devices

A GaN-Based Four-Switch Buck-Boost Converter Using Ripple Correlation Control for Maximum Power Point Tracking in Dynamic Deep Space Environments

As the demand for high-performance power conversion in spacecraft continues to grow and spacecraft mass and volume budgets become increasingly tight, it is essential to design DC-DC converters with higher efficiency and power density. Although photovoltaic (PV) efficiency has increased over time, solar irradiance and temperatures can fluctuate dramatically in deep space. This causes significant variations in the maximum power point (MPP) of the PV array, which can decrease the overall system efficiency unless accounted for. Thus, it is imperative to track the MPP of the PV panels to maintain optimal efficiency. This paper presents the experimental development of a four-switch, GaN-based buck-boost converter with an implementation of the Ripple Correlation Control (RCC) MPPT algorithm for dynamic deep space environments. Due to the use of GaN HEMTs, the experimental system achieves better efficiency and power density compared to the previous state of the art implementations. A simulation of the prototype buck-boost converter was implemented in SaberRD (Synopsis), and a digital design of the RCC-based MPPT controller utilizing the StateAMS tool is presented. The simulation results show that this controller swiftly and precisely converged to the MPP of the source PV panels in a dynamic solar irradiance condition

GaN-Based, Ultra-Compact Power Conversion System for the PUFFER Autonomous Mobility Platform

In the pursuit for the development of small rovers for planetary science missions, there is a distinct need for the development of an advanced, autonomously controlled, power subsystem. Existing bus management systems used in large spacecraft missions are not suitable for small spacecraft missions, as they are massive, relatively inefficient, and expensive. For extremely compact rover mission concept, newly developed high-density, high-efficiency, lightweight, and low-cost electronics are required. This paper presents a radiation-hardened power subsystem for the Pop-Up Flat-Folding Explorer Robot (PUFFER) mission concept, utilizing GaN-based converters for solar array conversion, battery management, and point of load applications to provide an extremely compact power subsystem

Soft-Switching GaN-Based Isolated Power Conversion System for Small Satellites with Wide Input Voltage Range

As we pursue the advancement of small satellites for space missions with more capabilities, there is a significant need for cutting-edge, modularly configurable, high density power converters. This article proposes a fixed switching frequency, high efficiency, compact isolated converter for sensitive loads such as radar, communication systems, or other instruments on small satellites

Small Form Factor Hybrid CMOS/GaN Buck Converters for 10W Point of Load Applications

abstract: Point of Load (PoL) converters are important components to the power distribution system in computer power supplies as well as automotive, space, nuclear, and medical electronics. These converters often require high output current capability, low form factor, and high conversion ratios (step-down) without sacrificing converter efficiency. This work presents hybrid silicon/gallium nitride (CMOS/GaN) power converter architectures as a solution for high-current, small form-factor PoL converters. The presented topologies use discrete GaN power devices and CMOS integrated drivers and controller loop. The presented power converters operate in the tens of MHz range to reduce the form factor by reducing the size of the off-chip passive inductor and capacitor. Higher conversion ratio is achieved through a fast control loop and the use of GaN power devices that exhibit low parasitic gate capacitance and minimize pulse swallowing. This work compares three discrete buck power converter architectures: single-stage, multi-phase with 2 phases, and stacked-interleaved, using components-off-the-shelf (COTS). Each of the implemented power converters achieves over 80% peak efficiency with switching speeds up-to 10MHz for high conversion ratio from 24V input to 5V output and maximum load current of 10A. The performance of the three architectures is compared in open loop and closed loop configurations with respect to efficiency, output voltage ripple, and power stage form factor. Additionally, this work presents an integrated CMOS gate driver solution in CMOS 0.35um technology. The CMOS integrated circuit (IC) includes the gate driver and the closed loop controller for directly driving a single-stage GaN architecture. The designed IC efficiently drives the GaN devices up to 20MHz switching speeds. The presented controller technique uses voltage mode control with an innovative cascode driver architecture to allow a 3.3V CMOS devices to effectively drive GaN devices that require 5V gate signal swing. Furthermore, the designed power converter is expected to operate under 400MRad of total dose, thus enabling its use in high-radiation environments for the large hadron collider at CERN and nuclear facilities.Dissertation/ThesisMasters Thesis Electrical Engineering 201

Miniaturized Ultraviolet Imager High Voltage Power Supply

Sending satellites into orbit becomes exponentially more expensive with weight and size, so designing high-voltage DC-DC converters that can achieve kilovolt level outputs in a small form factor is crucial to reducing costs. The Miniaturized Ultraviolet Imager (MUVI) aims to monitor Earth’s ionosphere and report weather patterns to climate scientists within a 2U cube satellite footprint. The imaging equipment consists of a microchannel plate and phosphor screen that require 2.5kV and 5.5kV respectively at microamp level currents. This report explains the implementation of a high voltage boost cascaded flyback converter to meet all of the MUVI satellite output voltage requirements. The small mechanical footprint of a cube satellite severely limits board size and component heights. This design further expands the power electronics field and provides inspiration for future space-rated voltage converters in small form factors. The results from circuit simulations validated the design as a viable solution for MUVI’s imaging equipment. A boost-flyback converter can achieve the required high voltage DC output while remaining within the 7ppm ripple specification. This report summarizes all of the circuit simulation results for both the power stage and analog circuitry that monitor and control the output voltage. The analog circuitry was hardware tested and validated for the monitoring and control signals. The power stage testing is scheduled for the Summer of 2021 so those results are not included in this report

Radiation-Tolerant, GaN-based Point of Load Converters for Small Spacecraft Missions

As computational loads for spacecraft continue to grow, the requirements levied on power-conversion electronics have become increasingly demanding. Designing for compute-intensive processing capabilities in the CubeSat form-factor further encourages the use of lightweight, compact, and efficient power-conversion electronics. However, the radiation-tolerant and radiation-hardened point-of-load converters available from existing vendors are large, expensive, and inefficient relative to their commercial counterparts. To alleviate this disparity, this paper presents the design, development, and testing of three radiation-tolerant, point-of-load (PoL) converters using Gallium Nitride (GaN) High-Electron Mobility Transistors (HEMT) and commercial controllers to enable the success of future small-satellite missions

A Novel RF Architecture for Simultaneous Communication, Navigation, and Remote Sensing with Software-Defined Radio

The rapid growth of SmallSat and CubeSat missions at NASA has necessitated a re-evaluation of communication and remote-sensing architectures. Novel designs for CubeSat-sized single-board computers can now include larger Field-Programmable Gate Arrays (FPGAs) and faster System-on-Chip (SoCs) devices. These components substantially improve onboard processing capabilities so that varying subsystems no longer require an independent processor. By replacing individual Radio Frequency (RF) systems with a single software-defined radio (SDR) and processor, mission designers have greater control over reliability, performance, and efficiency. The presented architecture combines individual processing systems into a single design and establishes a modular SDR architecture capable of both remote-sensing and communication applications. This new approach based on a multi-input multi-output (MIMO) SDR features a scalable architecture optimized for Size, Weight, Power, and Cost (SWaP-C), with sufficient noise performance and phase-coherence to enable both remote-sensing and navigation applications, while providing a communication solution for simultaneous S-band and X-band transmission. This SDR design is developed around the NASA CubeSat Card Standard (CS2) that provides the required modularity through simplified backplane and interchangeable options for multiple radiation-hardened/tolerant processors. This architecture provides missions with a single platform for high-rate communication and a future platform to develop cognitive radio systems

Reliability enhanced electrical power system for nanosatellites

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Elétrica, Florianópolis, 2023.A baixa confiabilidade dos subsistemas elétricos de potência (EPS) é um dos principais fatores responsáveis pelo alto número de falhas em missões de nanossatélites. Embora diversas técnicas de melhoria de confiabilidade tenham sido propostas no passado, a maior parte destes estudos não considera sua aplicabilidade, ignorando o custo, a energia e a área da placa requerida para que estas técnicas sejam implementadas. Em vista disto, o presente trabalho propõe uma arquitetura de EPS que incorpora quatro técnicas de melhoria de confiabilidade em um projeto de baixo custo e tamanho reduzido, a saber: seleção metódica de componentes de prateleira, projeto sem processador, redundância passiva parcial, e monitoramento e controle de cargas. Cada uma destas técnicas foi cuidadosamente selecionada para aprimorar a confiabilidade do EPS sem que outras áreas do projeto fossem comprometidas. Para melhor assegurar a viabilidade da arquitetura, três estratégias de projeto para redução de consumo energia foram também colocadas em prática. A mais importante delas é o uso de conversores de carga customizados, de alta eficiência e baseados em transistores de nitreto de gálio (GaN). Além disto, a arquitetura utiliza majoritariamente componentes de baixo consumo de energia e disponibiliza suporte para modos de operação de baixa dissipação, o que pode reduzir significativamente o desperdício de energia durante períodos de eclipse ou de inatividade. Toda a proposta foi fundamentada por diagramas de blocos, análises teóricas, equações de projeto e pelo esquema elétrico da placa de circuito impresso (PCB). A eficiência dos conversores de ponto de carga, o mecanismo de ativação das redundâncias passivas e todas as outras principais funcionalidades do EPS foram verificadas e validadas através de simulações de circuito SPICE. Ademais, um sistema de três métricas para avaliar e comparar a confiabilidade de arquiteturas de EPS também foi proposto. Baseado neste modelo de avaliação, foi possível comparar a arquitetura aqui apresentada, com aquela utilizada na versão anterior da mesma plataforma e com a NanoPower P31U, que é projetada pela GomSpace. Resultados comparativos confirmaram a efetividade das técnicas que foram incorporadas ao EPS, indicando que ele apresenta a arquitetura mais confiável dentre as três que foram consideradas para esta análise.Abstract: The low reliability of the Electrical Power Systems (EPS) is one of the major factors responsible for the high number of nanosatellite mission failures. Although several reliability-enhancing techniques have been proposed in the past, most studies do not take into account their applicability, overlooking the cost, power, and board area required for them to be implemented. In light of this, the present work proposes an EPS architecture that incorporates four reliability-enhancing techniques into a low-cost, small-footprint design. Namely, methodical COTS selection, processor-less design, partial standby redundancy, and load monitoring and control. Each technique was thoughtfully chosen to enhance the EPS reliability without compromising other design areas. To further ensure the viability of the architecture, three power reduction design strategies were also put in place. The most important of which was the use of customized high-efficiency GaN-based point-of-load (PoL) converters. In addition, the architecture features mostly low-power components and provides support for low-power modes of operation, which can greatly reduce the power wasted during an eclipse or an idle period. The entire proposal was backed up by block diagrams, theoretical analysis, design equations, and a printed circuit board (PCB) schematic design. The efficiency of the PoL converters, the standby redundancy activation mechanism, and all other main EPS functionalities, were verified and validated through SPICE circuit simulations. Furthermore, this work also proposes a three-metric system for evaluating and comparing the reliability of different EPS architectures. Based on this evaluation method, it was possible to compare the EPS architecture presented herein with its previous version and with the NanoPower P31U, which is designed by GomSpace. Comparison results confirmed the effectiveness of the techniques that were incorporated into this EPS, indicating that it exhibits the highest architecture reliability among the three candidates that were considered for this analysis