Engineering topics

Hopkins, Douglas C.

Publications and source records attributed to Hopkins, Douglas C..

10 records

DOE OSTI2023

PV Inverter Systems Enabled by Monolithically Integrated SiC based Four Quadrant Power Switch (4-QPS) [BiDFET]

The purpose of this project was to develop a new breed of Power Conversion Systems (PCS) for PV integration that is enabled by the newly developed 4-Quadrant Single Die SiC Power Semiconductor Switches (4-QPS) or also referred to as “Bidirectional FET (BIDFET)”. This work includes semiconductor die development, advanced packaging, converter design, development, and testing of 4-QPS enabled hardware prototypes at 1 kW (for single phase residential application) and 10 kW (for three phase commercial application). The BiDirectional Field-Effect Transistor (BiDFET) can enable circuit topologies requiring four-quadrant switches, that were earlier designed using discrete combinations of MOSFETs, IGBTs, GaN HEMTs, and PiN diodes. The monolithic nature of the BiDFET allows lower device count, smaller switch volume, lower inductance, and simpler packaging, and hence more reliable and commercially viable implementation in power electronics converters. The matrix converter topologies, now feasible using BiDFETs, can eliminate the bulky and unreliable dc link capacitors or inductors required for conventional voltage-source or current-source converters in ac–ac and ac–dc applications. The 1.2 kV BiDFET has the potential to disrupt all the applications utilizing 1.2 kV switches, including electric vehicle (EV) drivetrain, bidirectional EV chargers, industrial motor drives, solid-state transformers, datacenter power supplies, elevator drives, dc microgrids, energy storage grid integration, solid-state breakers, etc.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2023

Isolated Single-stage Three-phase AC/DC Converter using Bidirectional Switches

The advent of the SiC Bidirectional FET (BiDFET), a monolithic 1.2 kV bidirectional switch, has rendered the single-stage three-phase AC/DC converter topology a promising approach for implementing AC/DC converters. This topology, which integrates a full-bridge converter with a single-phase to three-phase matrix converter via a high-frequency transformer, is particularly suitable for applications requiring galvanic isolation, buck-boost functionality, and bidirectional power flow. The single-stage design eliminates the need for bulky and unreliable electrolytic capacitors, and utilizes a single magnetic component for power transfer. In the matrix converter, bidirectional switches, which were traditionally implemented using combinations of multiple semiconductor devices such as MOSFETs, IGBTs, and diodes, can now be realized using the single-chip solution, BiDFET. This advancement leads to a lower switch count, compact converter implementation, with lower inductance commutation cells, thereby enhancing the overall efficiency and compactness of the system. The paper presents a unified model of the converter, considering all control parameters, including the duty cycles and phase shift of transformer voltages. Detailed expressions for power transfer, transformer currents, and currents at AC and DC ports are provided. Additionally, the paper outlines the conditions necessary for soft-switching of all switches and the commutation schemes required for the practical implementation of the matrix converter modulation scheme. A hardware prototype of a 10 kW, 480 VRMS, LL/ 800 V AC/DC system has been developed, and experimental results are presented to demonstrate its performance.

BiDFET↗

DOE OSTI2023

Design and Optimization of High-frequency Transformer for Isolated Single-Stage Three-Phase AC/DC Converter using Bidirectional Switches

This paper presents the design and optimization of the high-frequency transformer for an isolated single-stage threephase AC/DC converter enabled by the 4H-SiC BiDirectional Field Effect Transistor (BiDFET). Non-dominated Sorting Genetic Algorithm II (NSGA-II) is used to perform a multiobjective optimization to minimize loss, weight, and volume. A 20 kW, 50 kHz hardware prototype based on the selected optimal point is characterized by a power amplifier. The finite element analysis simulation results are also presented to validate the core magnetic flux density and winding electric field strength. The experimental prototype was tested at 800 Vdc/480 Vrms at 10 kW rated power.

BiDFET, High-frequency transformer, Multiobjective↗

DOE OSTI2023

Bidirectional Three-phase Current Source Converter based Buck-boost AC/DC System using Bidirectional Switches

The 1.2 kV 4H-SiC BiDirectional Field Effect Transistor (BiDFET) is the first monolithic SiC bidirectional switch, which offers a lower voltage drop and semiconductor devices count alternative to the reverse-voltage-blocking (RB) switch used in the current-source converters (CSC). The bidirectional switch based CSC also allows DC-link current reversal for bidirectional power flow and provides multiple system-level benefits in a buck-boost AC/DC system consisting of buck-type DC/DC converter and CSC. This paper discusses the selection of buck converter duty cycle and CSC modulation index for the system’s buck-boost operation with a wide variation in DC voltage. CSC modulation schemes categorized based on the number of hard-turn-on transitions per switching cycle are also analyzed along with the three-step and four-step commutation schemes that are essential for the CSC commutation cells. Finally, the different schemes are evaluated and compared through the experimental results of a 10 kW, 480 VRMS, LL/ (400 − 800) V AC/DC system.

Bidirectional switches, four-quadrant switches, cu↗

DOE OSTI2023

Analysis and Characterization of Four-quadrant Switches based Commutation Cell

A four-quadrant switch (FQS) blocks either polarity voltage and controls current flow in both directions. Unlike voltage-source converters, in which two-quadrant switches operate over a narrow voltage range, four-quadrant switches are required to operate over a wide range of both voltage and current in applications such as matrix converters and current-source converters. Furthermore, matrix converters require multi-step commutation schemes compared to two-step schemes for current-bidirectional switch based voltage-source converters and voltage-bidirectional switch based current-source converters. This paper provides a generalized overview of commutation schemes used for two and four quadrant switches based two-level commutation cells, identifies comparison indices for FQS commutation schemes, and discusses the need for adaptive commutation-step times for wide voltage and current variation applications. Also, the static and dynamic characteristics of 1.2 kV rated FQS implementations utilizing commercial SiC MOSFETs from four different manufacturers and novel monolithic SiC BiDirectional Field Effect Transistor (BiDFET) have been reported.

Commutation cell, four quadrant switch, SiC Bidire↗

DOE OSTI2023

Power Conversion Systems Enabled by SiC BiDFET Device

The BiDirectional Field-Effect Transistor (BiDFET) can enable circuit topologies requiring four quadrant switches, that were earlier designed using discrete combinations of MOSFETs, IGBTs, GaN HEMTs and PiN diodes. The monolithic nature of the BiDFET allows lower device count, smaller switch volume, lower inductance, and simpler packaging, and hence more reliable and commercially viable implementation in power electronics converters. Furthermore, the matrix converter topologies, now feasible using BiDFETs, can eliminate the bulky and unreliable dc link capacitors or inductors required for conventional voltage-source or current-source converters in ac-ac and ac dc applications. The 1.2 kV BiDFET has the potential to disrupt all the applications utilizing 1.2 kV switches, including electric vehicle (EV) drivetrain, bidirectional EV chargers, industrial motor drives, solid-state transformers, datacenter power supplies, elevator drives, dc microgrids, energy storage grid integration, solid-state breakers, etc.

42 ENGINEERING↗

DOE OSTI2022

Design Considerations for Developing 1.2 kV 4H-SiC BiDFET-enabled Power Conversion Systems

Bidirectional switches are essential for cycloconverter and matrix converter applications to facilitate single-stage AC-AC conversion without intermediate energy storage elements. The 1.2 kV 4H-SiC BiDFET was developed as the first monolithic bidirectional SiC power transistor. This paper describes the design considerations taken into account while creating the BiDFET device and developing custom packages for housing the switch in discrete form for low power applications and in module form for high-power applications. The realized switches are characterized for their on-state and switching performance. The versatility of the BiDFET device is demonstrated by operating a single BiDFET H-bridge in voltage-source-inverter and current-source-inverter topologies only by varying the gate bias on the individual BiDFETs and reversing the input-output connections.

Bidirectional, Silicon Carbide, Half-Bridge Module↗

DOE OSTI2021

Thermal and Reliability Characterization of an Epoxy Resin-Based Double-Side Cooled Power Module

Wide-Band Gap (WBG) power devices have become a promising option for high-power applications due to the superior material properties over traditional Silicon. To not limit WBG devices’ mother nature, a rugged and high-performance power device packaging solution is necessary. This study proposes a Double-Side Cooled (DSC) 1.2 kV half-bridge power module having dual epoxy resin insulated metal substrate (eIMS) for solving convectional power module challenges and providing a cost-effective solution. The thermal performance outperforms traditional Alumina (Al2O3) Direct Bonded Copper (DBC) DSC power module due to moderate thermal conductivity (10 W/mK) and thin (120 mm) epoxy resin composite dielectric working as the IMS insulation layer. This novel organic dielectric can withstand high voltage (5 kVAC @ 120 μm) and has a Glass Transition Temperature (Tg) of 300°C, which is suitable for high-power applications. In the thermal-mechanical modeling, the organic DSC power module can pass the thermal cycling test over 1,000 cycles by optimizing the mechanical properties of the encapsulant material. In conclusion, this article not only proposes a competitive organic-based power module but also a methodology of evaluation for thermal and mechanical performance.

42 ENGINEERING↗

DOE OSTI2021

Characterization of Highly Thermally Conductive Organic Substrates for a Double-Sided Cooled Power Module

Abstract Silicon-Carbide (SiC) power devices have become a promising option for traditional Silicon (Si) due to the superior material properties. To fully take advantage of the SiC devices, a high-performance power device packaging solution is necessary. This study proposes a cost-effective double-sided cooled (DSC) 1.2 kV SiC half-bridge power module using organic epoxy-resin composite dielectric (ERCD) substrates. The high mechanical and thermal performance of the power module is achieved by the low-modulus, moderate thermal conductivity, and relatively thin (120 μm) layer of ERCD material compared with traditional metal-clad ceramic approaches. This novel organic dielectric can withstand high voltage (5 kV @ 120 μm) and operate up to 250°C continuously, which is indispensable for high power applications. The thermal modeling results show that the equivalent thermal resistance junction-to-case (Rjc_eq) of the DSC power module using dual direct bonded copper (DBC) is 17% higher than the dual ERCD configuration. Furthermore, a non-insulated DSC power module concept is proposed for maximizing thermal performance by considering thermal vias in the ERCD substrate and direct-soldered heat sink. A thought process for optimization of thermal via design is demonstrated and it shows up to 24% of improvement on thermal performance compared with the insulated DSC power module.

Double-sided cooling, epoxy-resin composite dielec↗

NASA NTRS1990

Current limiting remote power control module

The power source for the Space Station Freedom will be fully utilized nearly all of the time. As such, any loads on the system will need to operate within expected limits. Should any load draw an inordinate amount of power, the bus voltage for the system may sag and disrupt the operation of other loads. To protect the bus and loads some type of power interface between the bus and each load must be provided. This interface is most crucial when load faults occur. A possible system configuration is presented. The proposed interface is the Current Limiting Remote Power Controller (CL-RPC). Such an interface should provide the following power functions: limit overloading and resulting undervoltage; prevent catastrophic failure and still provide for redundancy management within the load; minimize cable heating; and provide accurate current measurement. A functional block diagram of the power processing stage of a CL-RPC is included. There are four functions that drive the circuit design: rate control of current; current sensing; the variable conductance switch (VCS) technology; and the algorithm used for current limiting. Each function is discussed separately.

Hopkins, Douglas C.↗