Design and Switching Performance Evaluation of a 10 kV SiC MOSFET Based Phase Leg for Medium Voltage Applications

10 kV SiC MOSFETs are promising to substantially boost the performance of future medium voltage (MV) converters, ranging from MV motor drives to fast charging stations for electric vehicles (EVs). Numerous factors influence the switching performance of 10 kV SiC MOSFETs with much faster switching speed than their Si counterparts. Thorough evaluation of their switching performance is necessary before applying them in MV converters. Particularly, the impact of parasitic capacitors in the MV converter and the freewheeling diode is investigated to understand the switching performance more comprehensively and guide the converter design based on 10 kV SiC MOSFETs.A 6.5 kV half bridge phase leg based on discrete 10 kV/20 A SiC MOSFETs is designed and fully validated to operate continuously at rated voltage with dv/dt up to 80 V/ns. Based on the phase leg, the impact of parasitic capacitors brought by the load inductor and the heatsink on the switching transients and performance of 10 kV SiC MOSFETs is investigated. Larger parasitic capacitors result in more oscillations, longer switching transients, as well as higher switching energy loss especially at low load current. As for the freewheeling diode, the body diode of 10 kV SiC MOSFETs is suitable to serve as the freewheeling diode, with negligible reverse recovery charge at various temperatures. The switching performance with and without the anti-parallel SiC junction barrier Schottky (JBS) diode is compared quantitatively. It is not recommended to add an anti-parallel diode for the 10 kV SiC MOSFET in the converter because it increases the switching loss

Converter- and Module-level Packaging for High Power Density and High Efficiency Power Conversion

Advancements in the converter- and module-level packaging will be the key for the development of the emerging high-power, high power-density, high-eciency power conversion applications, such as traction, shipboards, more-electric-aircraft, and locomotive. Wide bandgap (WBG) devices such as silicon carbide (SiC) MOSFET attract much attention in these applications for their fast switching speeds, resulting in low loss and a consequent possibility for high switching frequency to increase the power density. However, for high-current, high power implementations, WBG devices are still available in small die sizes. Multiple SiC devices need to be connected in parallel to replace a large IGBT die. It is challenging to realize high-switching-frequency and low loss with a lot of parallel devices due to the inherent parameter dierences, which lead to unbalanced dynamic current sharing resulting in unequal temperature distribution and overstress. Apart from the technical challenges, the price of SiC modules is another roadblock for its widespread application. The paralleling of a large number of SiC chips in the module to handle high current increases the module cost. Hence, this work proposes a Si-IGBT and SiC-MOSFET-based hybrid switch solution. For a converter-level packaging, the device technology, available device package, and orientation of the pins are the essential governing factors. This work addresses the converter-level packaging, which is referred to as a power electronics building block, of the proposed hybrid switch, combining discrete packages and frame-based modules for the devices and a singlephase three-level T-type topology. The primary optimization objective for converter-level packaging includes low inductance busbar design, high eciency, and high specic and volumetric power density. Overall implementation is not trivial; however, this work achieves an optimum design compared to the state-of-the-art. The module-level packaging challenges are dependent on the type of device technology and topology. Reducing the parasitic inductances, capacitances, and the junction to case thermal resistance are the optimization objectives in module packaging. Given the intended application of the module, achieving a high-reliability module is also essential. This work includes a hybrid switch-based power module addressing the challenges of WBG module-level packaging and challenges specic to the hybrid switch. The availability of engineering samples of SiC MOSFETs with voltage ratings above 10 kV and commercialization in the future drive the module-level packaging of high voltage devices. High voltage power modules will support the development of future solid-state circuit breakers, transformers, and power conversion applications in shipboards and rolling stocks. The availability of these modules can eliminate the necessity of multilevel topologies. This work investigates and demonstrates the module-level packaging of HV (10-15 kV) SiC MOSFETs

Multiple Output Power Supply using Toroidal Transformers for Medium Voltage Active Gate Drivers

When operating in high power applications, power devices dissipate tens or hundreds of watts of power in the form of heat. The ability of the power devices to withstand power and dissipation of heat across the power devices becomes a prominent requirement in designing the power converter. This challenge demands a power converter design to be more effective and consistent which factors in size, cost, weight, power density and reliability. This study aims to propose a gate driver isolated power supply design that can be used in medium voltage applications (e.g., up to 10 kV) while respecting the principle of scalability. A versatile design that facilitates addition of another power switch to the converter if needed, without having to alter too many power supply components while retaining the main structure, thus reducing system complexity and size. The proposed topology is a full-bridge converter with a single-turn primary side transformer, realized using a high voltage insulated hook-up wire as primary winding, while the secondary winding is wound around a toroidal core. This structure can supply several gate drivers simultaneously without replicating the primary side converter, but by simply adding a toroidal core with the secondary side converter which effectively reduces the size of the power supply. To satisfy magnetic and electric constraints, the proposed toroidal transformer needs to exhibit a very low primary to secondary coupling capacitance to avoid high common mode current, which leads to control signal distortion. For this, a multi-objective optimization design has been performed for the magnetic components of the topology. In this paper, a single input and three output power supply design is proposed for a 10 kV active gate driver

Multiple Output Power Supply using Toroidal Transformers for Medium Voltage Active Gate Drivers

When operating in high power applications, power devices dissipate tens or hundreds of watts of power in the form of heat. The ability of the power devices to withstand power and dissipation of heat across the power devices becomes a prominent requirement in designing the power converter. This challenge demands a power converter design to be more effective and consistent which factors in size, cost, weight, power density and reliability. This study aims to propose a gate driver isolated power supply design that can be used in medium voltage applications (e.g., up to 10 kV) while respecting the principle of scalability. A versatile design that facilitates addition of another power switch to the converter if needed, without having to alter too many power supply components while retaining the main structure, thus reducing system complexity and size. The proposed topology is a full-bridge converter with a single-turn primary side transformer, realized using a high voltage insulated hook-up wire as primary winding, while the secondary winding is wound around a toroidal core. This structure can supply several gate drivers simultaneously without replicating the primary side converter, but by simply adding a toroidal core with the secondary side converter which effectively reduces the size of the power supply. To satisfy magnetic and electric constraints, the proposed toroidal transformer needs to exhibit a very low primary to secondary coupling capacitance to avoid high common mode current, which leads to control signal distortion. For this, a multi-objective optimization design has been performed for the magnetic components of the topology. In this paper, a single input and three output power supply design is proposed for a 10 kV active gate driver

Design and Control of Power Converters 2020

In this book, nine papers focusing on different fields of power electronics are gathered, all of which are in line with the present trends in research and industry. Given the generality of the Special Issue, the covered topics range from electrothermal models and losses models in semiconductors and magnetics to converters used in high-power applications. In this last case, the papers address specific problems such as the distortion due to zero-current detection or fault investigation using the fast Fourier transform, all being focused on analyzing the topologies of high-power high-density applications, such as the dual active bridge or the H-bridge multilevel inverter. All the papers provide enough insight in the analyzed issues to be used as the starting point of any research. Experimental or simulation results are presented to validate and help with the understanding of the proposed ideas. To summarize, this book will help the reader to solve specific problems in industrial equipment or to increase their knowledge in specific fields

Power Interface Design and System Stability Analysis for 400 V DC-Powered Data Centers

The demands of high performance cloud computation and internet services have increased in recent decades. These demands have driven the expansion of existing data centers and the construction of new data centers. The high costs of data center downtime are pushing designers to provide high reliability power supplies. Thus, there are significant research questions and challenges to design efficient and environmentally friendly data centers with address increasing energy prices and distributed energy developments. This dissertation work aims to study and investigate the suitable technologies of power interface and system level configuration for high efficiency and reliable data centers. A 400 V DC-powered data center integrated with solar power and hybrid energy storage is proposed to reduce the power loss and cable cost in data centers. A cascaded totem-pole bridgeless PFC converter to convert grid ac voltage to the 400 V dc voltage is proposed in this work. Three main control strategies are developed for the power converters. First, a model predictive control is developed for the cascaded totem-pole bridgeless PFC converter. This control provides stable transient performance and high power efficiency. Second, a power loss model based dual-phase-shift control is applied for the efficiency improvement of dual-active bridge converter. Third, an optimized maximum power point tracking (MPPT) control for solar power and a hybrid energy storage unit (HESU) control are given in this research work. The HESU consists of battery and ultracapacitor packs. The ultracapacitor can improve the battery lifetime and reduce any transients affecting grid side operation. The large signal model of a typical solar power integrated datacenter is built to analyze the system stability with various conditions. The MATLAB/Simulink™-based simulations are used to identify the stable region of the data center power supply. This can help to analyze the sensitivity of the circuit parameters, which include the cable inductance, resistance, and dc bus capacitance. This work analyzes the system dynamic response under different operating conditions to determine the stability of the dc bus voltage. The system stability under different percentages of solar power and hybrid energy storage integrated in the data center are also investigated

Power Interface Design and System Stability Analysis for 400 V DC-Powered Data Centers

The demands of high performance cloud computation and internet services have increased in recent decades. These demands have driven the expansion of existing data centers and the construction of new data centers. The high costs of data center downtime are pushing designers to provide high reliability power supplies. Thus, there are significant research questions and challenges to design efficient and environmentally friendly data centers with address increasing energy prices and distributed energy developments. This dissertation work aims to study and investigate the suitable technologies of power interface and system level configuration for high efficiency and reliable data centers. A 400 V DC-powered data center integrated with solar power and hybrid energy storage is proposed to reduce the power loss and cable cost in data centers. A cascaded totem-pole bridgeless PFC converter to convert grid ac voltage to the 400 V dc voltage is proposed in this work. Three main control strategies are developed for the power converters. First, a model predictive control is developed for the cascaded totem-pole bridgeless PFC converter. This control provides stable transient performance and high power efficiency. Second, a power loss model based dual-phase-shift control is applied for the efficiency improvement of dual-active bridge converter. Third, an optimized maximum power point tracking (MPPT) control for solar power and a hybrid energy storage unit (HESU) control are given in this research work. The HESU consists of battery and ultracapacitor packs. The ultracapacitor can improve the battery lifetime and reduce any transients affecting grid side operation. The large signal model of a typical solar power integrated datacenter is built to analyze the system stability with various conditions. The MATLAB/Simulink™-based simulations are used to identify the stable region of the data center power supply. This can help to analyze the sensitivity of the circuit parameters, which include the cable inductance, resistance, and dc bus capacitance. This work analyzes the system dynamic response under different operating conditions to determine the stability of the dc bus voltage. The system stability under different percentages of solar power and hybrid energy storage integrated in the data center are also investigated