A Current-Dependent Switching Strategy for Si/SiC Hybrid Switch-Based Power Converters

Abstract: Hybrid switches configured by paralleling Silicon (Si) Insulated Gate Bipolar Transistors (IGBT) and Silicon Carbide (SiC) Metal-Oxide Semiconductor Field-Effect Transistors (MOSFET) have been verified to be a high-efficiency cost-effective device concept. In this paper, a current-dependent switching strategy is introduced and implemented to further improve the performance of Si/SiC hybrid switches. This proposed switching strategy is based on a comprehensive consideration of reducing device losses, reliable operation, and overload capability. Based on the utilization of such Si/SiC hybrid switches and the proposed switching strategy, a 15-kW single-phase H-bridge inverter prototype was implemented and tested in the laboratory. Simulation and experimental results are given to verify the performance of the hybrid switches and the new switching strategy

An Advanced Three-Level Active Neutral-Point-Clamped Converter With Improved Fault-Tolerant Capabilities

A resilient fault-tolerant silicon carbide (SiC) three-level power converter topology is introduced based on the traditional active neutral-point-clamped converter. This novel converter topology incorporates a redundant leg to provide fault tolerance during switch open-circuit faults and short-circuit faults. Additionally, the topology is capable of maintaining full output voltage and maximum modulation index in the presence of switch open and short-circuit faults. Moreover, the redundant leg can be employed to share load current with other phase legs to balance thermal stress among semiconductor switches during normal operation. A 25-kW prototype of the novel topology was designed and constructed utilizing 1.2-kV SiC metal-oxide-semiconductor field-effect transistors. Experimental results confirm the anticipated theoretical capabilities of this new three-level converter topology

Investigation of Fault-Tolerant Capabilities in an Advanced Three-Level Active T-Type Converter

A novel fault-tolerant three-level power converter topology, named advanced three-level active T-Type (A3L-ATT) converter, is introduced to increase the reliability of multilevel power converters used in safety-critical applications. This new fault-tolerant multilevel power converter is derived from the conventional T-Type converter topology. The topology has significantly improved the fault-tolerant capability under any open circuit or certain short-circuit faults in the semiconductor devices. In addition, under healthy condition, the redundant phase leg can be utilized to share overload current with other main legs, which enhances the overload capability of the converter. The conduction losses in the original outer devices can be reduced by sharing the load current with the redundant leg. Moreover, unlike other existing fault-tolerant power converters in the literature, full output voltages can be always obtained in this proposed A3L-ATT converter during fault-tolerant operation. A 13.5-kW ATT-A3L converter prototype was developed and constructed using silicon carbide MOSFETs. Simulation and experimental results were obtained to substantiate the theoretical claims of this new fault-tolerant power converter

Efficiency Improvement of Fault-Tolerant Three-Level Power Converters

Fault-tolerant power converters play a critical role in the transportation electrification. However, fault-tolerant operation, high efficiency, and low cost usually result in design criteria that have conflicting constraints and goals. The majority of the fault-tolerant power converter topologies presented in the literature confirm these conflicts. In this paper, three types of fault-tolerant neutral-point clamped (NPC) converters are investigated. Various modulation strategies are explored to reduce the losses of the redundant phase leg. The simulation and experimental results show that the Switching Frequency Optimal Phase opposition Disposition modulation strategy is the most effective approach in minimizing the losses in the redundant phase leg

A Fault-Tolerant T-Type Multilevel Inverter Topology With Increased Overload Capability and Soft-Switching Characteristics

he performance of a novel three-phase four-leg fault-tolerant T-type inverter topology is introduced in this paper. This inverter topology provides a fault-tolerant solution to any open-circuit and certain short-circuit switching faults in the power devices. During any of the fault-tolerant operation modes for these device faults, there is no derating required in the inverter output voltage or output power. In addition, overload capability is increased in this new T-type inverter compared to that in the conventional three-level T-type inverter. Such increase in inverter overload capability is due to the utilization of the redundant leg for overload current sharing with other main phase legs under healthy condition. Moreover, if the redundant phase leg is composed of silicon carbide metal-oxide-semiconductor field-effect transistors, quasi-zero-voltage switching, and zero-current switching of the silicon insulated-gate bipolar transistors (IGBTs) in the conventional main phase legs can be achieved at certain switching states, which can significantly relieve the thermal stress on the outer IGBTs and improve the whole inverter efficiency. Simulation and experimental results are given to verify the efficacy and merits of this high-performance fault-tolerant T-type inverter topology

A Bidirectional Soft-Switched DAB-Based Single-Stage Three-Phase AC–DC Converter for V2G Application

In vehicle-to-grid applications, the battery charger of the electric vehicle (EV) needs to have a bidirectional power flow capability. Galvanic isolation is necessary for safety. An ac-dc bidirectional power converter with high-frequency isolation results in high power density, a key requirement for an on-board charger of an EV. Dual-active-bridge (DAB) converters are preferred in medium power and high voltage isolated dc-dc converters due to high power density and better efficiency. This paper presents a DAB-based three-phase ac-dc isolated converter with a novel modulation strategy that results in: 1) single-stage power conversion with no electrolytic capacitor, improving the reliability and power density; 2) open-loop power factor correction; 3) soft-switching of all semiconductor devices; and 4) a simple linear relationship between the control variable and the transferred active power. This paper presents a detailed analysis of the proposed operation, along with simulation results and experimental verification

A Fault-Tolerant T-Type Multilevel Inverter Topology with Soft-Switching Capability Based on Si and SiC Hybrid Phase Legs

The performance of a novel three-phase four-leg fault-tolerant T-Type inverter topology is presented in this paper, which significantly improves the inverter\u27s fault-tolerant capability regarding device switch faults. In this new modular inverter topology, only the redundant leg is composed of Silicon Carbide (SiC) power devices and all other phase legs are constituted by Silicon (Si) devices. The addition of the redundant leg, not only provides fault-tolerant solution to switch faults that could occur in the T-Type inverter, but also can share load current with other phase legs. Moreover, quasi zero-voltage switching (ZVS) and zero-current switching (ZCS) in the Si Insulated-Gate Bipolar Transistors (IGBTs) of the main phase legs can be achieved with the assistance of SiC Metal-Oxide Semiconductor Field-Effect Transistors (MOSFETs) in the redundant leg. Simulation and experimental results are given to verify the efficacy and merits of this high-performance fault-tolerant inverter topology

Electrothermal Design of a GaN-Based Axially Stator Iron-Mounted Fully Integrated Modular Motor Drive

The concept of More Electric Aircraft (MEA) has gained a lot of attention from researchers recently. For such an application, two of the pivotal requirements are having a power dense and energy efficient propulsion system. To that end, in the design procedure of the electric motor and its drive system, high power density and efficiency over the entire operating range is the ultimate goal. Thus, the integration of the electric motor and drive system into a single unit has been introduced as an effective method to meet the design objectives. Therefore, this paper presents the design procedure of a module of an Integrated Modular Motor Drive (IMMD). Electrothermal design of the GaN single phase full bridge inverter module has been conducted and the results are discussed. The analysis includes the thermal investigation of the WBG semiconductors by sweeping the number of parallel devices in each switch position at different switching frequencies. Furthermore, a single drive PCB module is designed and evaluated in ANSYS Q3D for parasitic extraction. Finally, double pulse test (DPT) is performed to verify the optimal design of PCB busbar

Reliability and Performance Improvement of PUC Converter Using a New Single-Carrier Sensor-Less PWM Method with Pseudo Reference Functions

A new single-carrier sensor-less pulsewidth modulation (PWM) method using suggested pseudo reference functions is proposed for packed U-cell (PUC) converter to improve performance and reliability of the PUC converter. It is composed of one PWM carrier signal and two suggested pseudo reference functions. By employing the proposed modulation method, the PUC dc capacitor voltage ripple is substantially decreased, and faster sensor-less capacitor voltage balancing is obtained. Moreover, the power losses are evenly distributed among all power switches. Consequently, notable reduction of the PUC dc capacitor voltage ripple and even distribution of the power loss among switches enhance the PUC converter\u27s reliability and lifetime. In addition, odd multiples of the switching harmonic clusters are eliminated from the output voltage; thus, the values of output passive filter components are halved. Hence, applying the proposed single-carrier sensor-less PWM method remarkably improves the performance, power density, reliability, and lifetime of the PUC converter and notably simplifies implementation of the switching pattern. Provided experimental results and comparisons as well as reliability analysis verify the viability and effectiveness of the proposed PWM method