High Power and Medium Voltage SiC based Power Converters and Applications Opportunities and Challenges offered by HV SiC Power Devices

Subhashish Bhattacharya 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Medium Voltage Asynchronous Micro-grid Power Conditioning System enabled by HV SiC Devices

Sanket Parashar,Subhashish Bhattacharya 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This research paper addresses a Medium-Voltage Asynchronous Micro-grid Power Conditioning system enabled by HV SiC devices to Asynchronously flow power from microgrids to the larger grid. The Asynchronous Microgrid Power Conditioning System is a modular MVAC (13.8kV AC) to MVAC (4,160 V AC and 13.8 kV AC) power conditioning systems blocks (PCSB) that can be used for grid interconnection of Megawatt-scale flow control microgrids (Asynchronous MVAC Microgrids), bidirectional power flow capablity and scalablity so that they can be used for a broad range of flow control microgrids of different scale (100 kW to multi MW) including microgrids which have net generation or net load flow at point of connection of larger grids. This modular approach is intended to result in highervolume, lower-cost power electronics building blocks that service many applications at standard voltages: 4,160 V AC and 13.8 kV AC. This Microgrid PCS solution should enable multi-port integration of renewable energy sources to the main grid. The Microgrid PCS solution can be implemented with 3.3 kV to 10 kV SiC MOSFET modules. The modular converters will utilize highvoltage, high frequency (10 kHz) power electronics to reduce cost, size , footprint, volume and weight and to provide the bandwidth (voltage control BW = 300 Hz and current control BW = 1 kHz) needed for both the grid-facing and microgrid facing functions required by interconnection standards plus functions required for a wide range of generator, storage and load applications.

Evaluation of Extra High Voltage (XHV) Power Module for Gen3 10 kV SiC MOSFETs in a Mobile Utility Support Equipment based Solid State Transformer (MUSE-SST)

Anup Anurag,Sayan Acharya,Subhashish Bhattacharya 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

MV solid state transformers enabled by SiC semiconductor devices is a promising replacement to conventional low frequency transformers. However, when MV SiC devices are used in converter applications, they are exposed to a high peak stress (5 kV to 10 kV) and a very high dv / dt (10 kV/μs to 100 kV/μs). Operating these semiconductor devices at these high peak stresses require careful designing from the packaging point of view, as well as designing the auxiliary systems such as the gate drivers and busbars, to handle the peak stress conditions. Recently, an extra high voltage (XHV) power module has been developed by Wolfspeed to package the 10 kV SiC MOSFETs for continuous and reliable operation. This paper aims at testing these modules in continuous operation for qualifying their operation in a MV solid state transformer. Reliable operation of these modules require the development of reliable auxiliary parts including gate drivers, bus bars and inductors. Design and development of the auxiliary system is also carried out. Successful tests demonstrating operation at MV levels are also shown. These tests serve as a qualification method for using these devices in a MV solid state transformer. It is envisaged that successful operation of these devices would accelerate the growth and deployment of MV SiC devices for field operation.

Improved EEMF-Based Position Sensorless Control for Non-sinusoidal Back-EMF PMSMs

Kim Heonyoung,Lee Kibok,Bhattacharya Subhashish 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.2

A restricted number of the stator and rotor slots in PMSMs distorts the air-gap fl ux distribution and eff ective air-gap length. Such distortions result in varying machine parameters with rotor position. In particular, the rotor fl ux linkage harmonics cause a non-sinusoidal back-EMF, which introduces machine harmonic currents if PI current controllers are employed. As a result, it deteriorates the rotor position estimation performance in extended EMF (EEMF)-based sensorless control. This is because both sinusoidal machine current and back-EMF are assumed for the rotor position estimation. Such degradation of the angle estimation performance can result in controller trips due to overcurrent, especially in the case of step load changes. This paper presents a detailed modeling of the harmonic rotor fl ux linkage and voltage, and introduces virtual rotor fl ux linkage terms in the synchronous reference frame to simplify the harmonic voltage terms. From the harmonic voltage model, a harmonic voltage injection method is proposed in addition to conventional EEMF-based sensorless control. The proposed scheme can provide sinusoidal motor current control for entire operating conditions. Additionally, experimental results confi rm that the proposed control method can achieve the improved performance of the EEMF-based sensorless control

The Influence of the LC with Clamping Diodes dv/dt Filter on Current Control of PMSM Drives in Case of Inverter Output Current Sensing and Its Compensation

Heonyoung Kim,Byeong-Heon Kim,Subhashish Bhattacharya 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper presents effect of LC with clamping diodes dv/dt filter on current-controlled PMSM drives in case where 3-phase inverter output currents are measured and used in the digital control loop. In particular, this case can be reported in some cases. Firstly, power devices are equipped with integrated pilot current sensors. Secondly, PCB technology based Rogowski coils are installed in inverter leg with analog circuit to feed a signal to microcontroller. Thirdly, hall type current sensors are packaged in inverter output terminal through a bus bar. In those cases, it is inevitable to measure inverter currents because it is hard to move the location of current sensor. In this manner, the effect of filter resonance should be considered properly to control the motor current accurately because the measured inverter output current includes both motor and filter resonant current. If the resonant current of the filter is not compensated properly, it causes the DC offset of motor current which bring about the torque ripples. In order to compensate the offset, inserting a two stage Discrete Fourier Transform (DFT) is used and the calculated offset is subtracted from the sampled current. Judging by simulation and experimental results, it is confirmed that the compensation method eliminates the offset of the motor current effectively, and thereby reducing the torque ripple as well.

Modeling and Stability Assessment of Single-Phase Droop Controlled Solid State Transformer

Yos Prabowo,Vishnu Mahadeva Iyer,Byeongheon Kim,Subhashish Bhattacharya 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper addresses the modeling aspects and small-signal stability considerations for a single-phase droop controlled Solid State Transformer (SST). A state-space based modeling approach is utilized to assess the stability of the SST. It is demonstrated that physical parameter (e.g. grid impedance) variations, the choice of control parameters (e.g. droop control parameters) and the steady state operating point play a crucial role in determining the stability of the SST system that needs to handle wide load variations. Simulation results from a 1kVA droop-controlled SST system are presented to validate the analytical models.

Design and Performance Evaluation of 1.2 kV, 325 A SiC-MOSFET High Performance Module based 100 kVA Three-phase Two-level Power Block

Sayan Acharya,Anup Anurag,Nithin Kolli,Subhashish Bhattacharya 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

To ramp up the adaptation of the highly optimized high current 1.2 kV Sillicon Carbide (SiC) based Metal Oxide Semiconductor Field Effect Transistor (MOSFET) power modules, a high power three-phase two-level power block is designed which is rated at 100 kVA and operates with 800 V DC bus. The power modules combined with low inductance busbar and optimized loop thermo-syphon based heatsink extracts the full performance of the power electronic switches. In this paper, the design details of the power block is presented. Furthermore, the performance of the power block is qualified by a back-to-back pump back test set up where two power blocks are interconnected via inductors. Furthermore, closed loop voltage and current control are implemented to circulate the desired amount of AC current between the power blocks. Moreover, heat run tests are carried out to quantify the thermal performance of the thermal management system. The experimental results demonstrate the performance benefits of the power block.

Grid Connected CM Noise Considerations of a Three-Phase Multi-Stage SST

Awneesh Tripathi,Sachin Madhusoodhanan,Krishna Mainali,Arun Kadavelugu,Dhaval Patel,Subhashish Bhattacharya,Kamalesh Hatua 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

Solid State Transformer (SST) is an alternative to the conventional distribution transformer for smart grid applications. By employing a compact Medium-Frequency (MF) transformer for isolation, the SST has merits on size and weight. It also provides flexible utilization as a FACTS component. The switching converters are a potential source of Common-Mode (CM) and HF EMI noises. These noises are more nuisance in a SiC device based SST which switches at a high dV/dT at the Medium-Voltage (MV) level resulting in high CM voltages. The SST floating metalic surfaces such as heatsink and the output must be grounded for safety and smooth operation. However there are various significant low impedance paths present, including the parasitics of the compact transformer, which may conduct CM noise to the grid. The generated CM noise may affect the controls. This paper presents the CM and grounding challenges in the multistage integration of a three-phase SST system based on 15kV SiC IGBTs termed as Transformerless Intelligent Power Substation (TIPS). The TIPS interfaces MV 13.8kV and LV 480V grids using MV ac-dc, MV to LV dc-dc dual active bridge and LV dc-ac inverter stages. A study on the CM noise in the TIPS and a passive filter solution for its attenuation is presented in this paper. A time domain simulation considering the passive filter specification is also presented. The experimental results for line to line 3.64kV MV grid integration are presented. A LV prototype is used to verify the complete grounding and the CM choke design at a scaled-down condition.