Hesam Mirzaee

Design comparison of 6.5 kV Si-IGBT, 6.5kV SiC JBS diode, and 10 kV SiC MOSFETs in megawatt converters for shipboard power system

In this paper a comparative design study has been shown with 6.5kV Si-IGBT/Si-P IN diode, 6.5kV Si-IGBT/SiC-JBS diode, and 10kV SiC-M OSFET/SiC-JBS diode in an act ive front-end (AFE) converter for medium-voltage shipboard application. Megawatt converters based on the aforementioned technologies are being designed and compared at tw o different switching frequencies. In this regard, accurate circuit models for 5-10A die for each (a) silicon 6.5kV IGBT, (b) 6.5kV Si-IGBT incorporating a 6.5kV SiC-JB S Diode, and (c) 10kV SiC MOSFET with 10kV SiC JBS Diode, are paralleled to ma ke a 100A switch and used as conv erter switching devices in SPICE circuit simulation to perform the comparative analysis. Switching waveforms, characteristics, switching power and energy loss measurements are follo wed by an efficiency comparison of a 1MW converter with 7.5kVdc at 1kH z and 5kH z switching frequencies. It is shown that 6.5kV Si-IGBT/SiC-JBS diode, with its high efficiency performance up to 5kHz, is a strong candidate for MW ran ge converters. The 10kV SiC-MOSFET/SiC-JBS diode is an option for h igher switching frequency MW converters.

Design Comparison of High-Power Medium-Voltage Converters Based on a 6.5-kV Si-IGBT/Si-PiN Diode, a 6.5-kV Si-IGBT/SiC-JBS Diode, and a 10-kV SiC-MOSFET/SiC-JBS Diode

In this paper, a comparative design study of high-power medium-voltage three-level neutral-point-clamped converters with a 6.5-kV Si-IGBT/Si-PiN diode, a 6.5-kV Si-IGBT/SiC-JBS diode, and a 10-kV SiC-MOSFET/SiC-JBS diode is presented. A circuit model of a 100-A power module, including packaging parasitic inductances, is developed based on device die SPICE-based circuit models for each power device. Switching waveforms, characteristics, and switching power and energy loss measurements of the power modules, including symmetric/asymmetric parasitic inductances, are presented. High-power converter designs and SPICE circuit simulations are carried out, and power loss and efficiencies are compared for a pulsewidth-modulated (PMW) 1-MW power converter at 1-, 5-, and 10-kHz switching frequencies for application in shipboard power system and a PWM vector-controlled and a line-frequency angle-controlled 20- to 40-MVA power converter at 60-Hz, 540-Hz, and 1-kHz switching frequencies for active mobile substation application. It is shown that the 6.5-kV Si-IGBT incorporating an antiparallel SiC-JBS diode, with its high efficiency performance up to 5-kHz switching frequency, is a strong candidate for megawatt-range power converters. The 10-kV SiC-MOSFET/SiC-JBS diode remains an option for higher switching frequency (5-10 kHz) high-power converters.

A three-phase three winding topology for Dual Active Bridge and its D-Q mode control

A new Dual Active Bridge (DAB) topology is proposed with a 15-kV SiC-IGBT based three-level inverter at the high-voltage side and 1200-V SiC-MOSFET based paralleled two-level inverter at the low-voltage side. The proposed DAB is an integral part of a solid state transformer which connects a 13.8-kV distribution grid and a 480-V utility grid. The three-level inverter connected at the high-voltage side and a pair of two-level inverters connected at the low-voltage sides (in Y/Δ) of the high frequency link transformer help to reduce dominant harmonic currents. Thus harmonic-free currents in the high frequency link transformer are achieved without pulse-width modulation. A simple control is proposed and validated with simulation results.

A medium-voltage DC (MVDC) with series active injection for shipboard power system applications

Modern electric ships utilize a medium-voltage zonal dc distribution system to meet the ever increasing power demand while keeping the power density as low as possible. Power electronics building blocks (PEBBs) composed of different DC/AC and DC/DC converters are used to convert the main DC bus voltage to appropriate dc and ac voltage levels suited for the loads in such a system. Due to the fact that most of these power electronic converters present a constant power load (CPL) with negative incremental impedance at the input terminal, the interaction of these converters under different system configurations with the main AC-DC rectifier of the MVDC system might induce voltage oscillations on the main DC-bus. In this paper, a novel method of series active injection on the dc-side is proposed to smooth out disturbances on the main DC-bus. This has resulted in much smoother DC-bus voltage enabling the system to use less amount of passive storage elements on dc-side which is very beneficial to ships limited onboard space. The simulation results presented verify the operation and functionality of the proposed system.

A high power medium-voltage dc amplifier system

In this paper the concept of a medium-voltage dc amplifier system is proposed. The dc amplifier system must provide a medium-voltage dc bus with the possibility of superposing a high bandwidth time-varying signal and should be capable of producing voltage excursions at a high slew-rate. This is intended to facilitate the development of new technologies, i.e. new high power non-linear loads based on power electronics, in all electric ships as part of the newly proposed MVDC ship power system. This paper sets forth the set of parameters and specifications of the medium-voltage dc amplifier system and proposes a specific circuit topology to achieve the required characteristics. Simulation results verify the feasibility and demonstrate highly dynamic performance of the proposed system configuration.

Supplementary Energy Storage and Hybrid Front-End Converters for High-Power Mobile Mining Equipment

To supply the high-power ac-drive systems of the mining equipment, several active front ends with dc choppers are used to ensure reliable operation and an acceptable harmonic current spectrum. Recently, the integration of the energy storage system with the mining equipment has received industry attention, particularly for peak load shaving and smarter energy management of the mines. Currently, the regenerative energy is often burned into the choppers and is not fed back to the grid. The industry is motivated to capture this regenerative energy since it can be as high as 60% of the motoring power, as high as 3 MJ in every operation cycle, and as high as 24-MW peak power. Therefore, there is a possibility of large cost reductions and component rating reduction. In this paper, we investigate the operation of the current state-of-the-art front-end converter systems for multimotor applications. In particular, we propose power conversion configurations and methodology to determine the suitable energy storage technology for the development of the multimotor mobile mining equipment that has encouraging incentives for both the manufacturers and the mine operators.

Development of solid-state fault isolation devices for future power electronics-based distribution systems

This paper addresses the timely issues of modeling, and defining selection criteria for, a solidstate fault isolation device (FID) intended for use in power electronics-based distribution systems (PEDS). The paper subsequently derives the FID parameters in the PEDS envisioned under a new multi-university Engineering Research Center funded by the US National Science Foundation. When conventional circuit breakers are used in distribution systems, they have relatively long clearing times, causing feeder voltages to be reduced for a significant amount of time. Although acceptable in convention systems, this relatively long clearing time would cause significantly long, complete voltage collapses in a PEDS. Sensitive loads such as computers would fail even if the voltage returns within a few seconds. However, if a semiconductor circuit breaker were to be used instead of the conventional system, it would be able to switch fast enough to keep the time of voltage disturbances within acceptable limits. This paper discusses the management of the overvoltage resulting from very fast circuit breaker operation through the use of passive clamping devices and di/dt control during turn-off. The paper includes experimental results at medium voltage from a developed hardware prototype. In addition, a validated simulation model of a medium voltage FID was developed for future studies. Simulation results are presented.

Design and control of Series DC Active Filter (SDAF) for shipboard Medium-Voltage DC power system

Shipboard power system (SPS) can have either ac or dc distribution systems, or a combination of both ac and dc distribution systems. However, the Navy has identified Medium-Voltage DC (MVDC) as a long-term solution for electric power distribution to meet the high power density requirements in future shipboard power systems. Thyristor bridges are a viable front-end converter topology due to its mature technology, high efficiency, and high current capacity. In such medium-voltage dc systems providing a highly stabilized low-ripple dc-bus is crucial for the reliable operation of entire system. In this paper, a 7.5kV Medium-Voltage DC (MVDC) system based on a twelve-pulse thyristor-bridge configuration is proposed. The system incorporates a Series DC Active Filter (SDAF) to smooth out DC link ripples and improves overall system damping. Detailed design, system components and control, and simulation results for the series DC active filter system are presented in the paper.

Design issues in a medium-voltage DC amplifier with a multi-pulse thyristor bridge front-end

In this paper the design issues of a medium-voltage DC amplifier with a multi-pulse thyristor bridge front-end are presented. A medium voltage dc amplifier is needed in de-risking new technologies coming onboard future electric ships. Based on the required system dynamic specifications, an initial design reveals the problems with a multi-pulse thyristor front-end, and then provides a novel solution to meet the requirements, are presented. The proposed system solution is validated through both simulation and experimental results.

Performance investigation of hybrid converter systems for mobile mining applications

To supply the AC high power drive systems, several Active Front-Ends (AFEs) with DC choppers are currently used to ensure reliable operation and an acceptable harmonic current spectrum. Recently, integration of the energy storage system with the mining equipment as an example of large mobile multimotor applications has received industry attention, especially for peak load shaving and energy management of the mines. Currently, the regenerative energy is often burnt into the choppers. The industry is motivated to capture this regenerative energy since it can be as high as 60% of the motoring power, as high as 3MJ in every operation cycle and 24 MW peak power. Hybrid approach for the front-end converter system has shown a technology path to deploy on-board energy storage without sacrificing the efficiency and reliability of the entire system. This paper addresses the dynamic performance analysis of such systems through detailed simulation and laboratory scale experiments.