Table of contents monday, September 9, 1: 30pm-4: 00pm modular Multi-Level Converters, hvdc, and dc grids I 3
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- Bu səhifədəki naviqasiya:
- Wide Bandgap Applications: Comparative Studies
- Gate Drive Techniques I
- Wireless Power Transfer II
| 9:20AM Fault Tolerant Capability of Deadbeat - Direct Torque and Flux Control for Three-Phase PMSM Drives [#335]
Mario Pulvirenti, Giuseppe Scarcella, Giacomo Scelba and Robert D. Lorenz, University of Catania, Italy; University of Wisconsin-Madison, United States This paper investigates the performance of a three phase permanent magnet synchronous machine (PMSM) drive operating under a single fault, adopting a fault tolerant (FT) control, based on deadbeat - direct torque and flux control (DB-DTFC). DB-DTFC offers an independent regulation of the electromagnetic torque and the stator flux linkage by using a control law based on an inverse discrete time physical model. During fault conditions, the PMSM drive requires very limited hardware and software reconfigurations. The drive model equations result very similarly to those adopted for the healthy electric drive just by using a different matrix transformation set when the drive operates under a faulty condition. The proposed fault tolerant DB-DTFC ensures satisfactory faulty operations and drive stability, without increasing the computational efforts. 9:45AM Online MTPA Control for Salient-Pole PMSMs Using Square-Wave Current Injection [#569]
The maximum torque per ampere (MTPA) control has been widely employed to improve the efficiency of the permanent-magnet synchronous machine (PMSM) drive systems. To achieve accurate online MTPA tracking, in this work, a high- frequency current injection based method is proposed. Compared to the lookup- table based MTPA control, the proposed method can significantly reduce the pre-tuning effort. Since a high-frequency square-wave signal is injected, compared to the existing sinusoidal signal injection based MTPA control, the proposed method can eliminate the bandpass filter, which is usually used to extract the derivative of torque with respect to the current control angle, such that the bandwidth of the MTPA controller can be increased. In this work, the proposed MTPA tracking can be implemented by using either virtual or real signal injection. In addition, the effect brought by magnetic saturation is analyzed in this work and the corresponding solutions are presented to mitigate this effect. The feasibility and effectiveness of proposed methods are verified by both simulation and experimental studies. 10:10AM Automatic MTPA Tracking in IPMSM Drives: Loop Dynamics, Design and Auto-Tuning [#1529]
In the control of Interior Permanent Magnet Synchronous Machines (IPMSMs), Maximum Torque Per Ampere (MTPA) based on motor parameters is a common approach to achieve high efficiency and torque density. Parametric uncertainty (e.g. due to identification errors, magnetic saturation or temperature variation) results in undesired deviation from the optimal operating trajectory. To solve this problem, MTPA tracking methods have been proposed, which exploit signal injection to search the minimum current point for a certain load torque, in a closed loop fashion. For one of these methods, [13], stability of the non linear dynamics was analyzed, and an upper bound for the convergence time was found, but no explicit method was proposed for the design of the tracking regulator. In this paper this last topic is addressed. By introducing some approximations, the linearized system is calculated and a loop transfer function obtained, which is invariant with the operating point. Thus, by means of a very simple design rule (i.e. suitable for auto tuning), the MTPA tracking regulator gains can be designed in order to obtain the desired bandwidth. The method has been studied analytically and in simulation, also considering the influence of noise and parametric uncertainties. Finally the technique has been implemented on the hardware of a commercial industrial drive, proving the effectiveness of the proposal. 10:35AM Reduction of Unbalanced Axial Magnetic Force in Post-fault Operation of a Novel Six-phase Double-stator Axial Flux PM Machine Using Model Predictive Control [#943]
This paper investigated the post-fault operation of a novel six-phase double-stator axial flux permanent magnet machine with detached winding configuration, which was found to be superior to existing winding configuration in previous study. However, the unbalanced magnetic force problem still remains unsolved. In this paper, the axial force balancing control principle is proposed and a group of specific current waveforms are deduced. When applying these currents under post-fault condition, magnetic torque, axial magnetic force and rotor losses of the machine are calculated in finite element analysis. The results are compared with normal condition and commonly-used post-fault current waveforms. It is verified that this method reduced the unbalanced axial magnetic force immensely and the torque ripple was also kept at a low level. In order to achieve the proposed current waveform, finite control set model predictive control (FCS-MPC) is adopted. This paper proposed the post-fault model of dual three-phase permanent magnet machines and designed a cost function to track the desired current waveforms. The model of the machine is used to predict the future behavior of the controlled variables and the cost function decides the next step of the inverter by evaluating all the predictions. At last, it is verified by simulation results that the control strategy performs well in both dynamic and steady-state situations. Wide Bandgap Applications: Comparative Studies Tuesday, September 20, 8:30AM-11:00AM, Room: 202C, Chair: David Reusch, Robert Pilawa-Podgurski 8:30AM Comparative Evaluation of 15 kV SiC IGBT and 15 kV SiC MOSFET for 3- Phase Medium Voltage High Power Grid Connected Converter Applications [#1605] Sachin Madhusoodhanan, Krishna Mainali, Awneesh Tripathi, Arun Kadavelugu, Kasunaidu Vechalapu, Dhaval Patel and Subhashish Bhattacharya, North Carolina State University, United States The advent of high voltage (HV) wide band-gap power semiconductor devices has enabled the medium voltage (MV) grid tied operation of non-cascaded neutral point clamped (NPC) converters. This results in increased power density, efficiency as well as lesser control complexity. The multi-chip 15 kV/40 A SiC IGBT and 15 kV/20 A SiC MOSFET are two such devices which have gained attention for MV grid interface applications. Such converters based on these devices find application in active power filters, STATCOM or as active front end converters for solid state transformers. This paper presents an experimental comparative evaluation of these two SiC devices for 3-phase grid connected applications using a 3-level NPC converter as reference. The IGBTs are generally used for high power applications due to their lower conduction loss while MOSFETs are used for high frequency applications due to their lower switching loss. The thermal performance of these devices are compared based on device loss characteristics, device heat-run tests, 3-level pole heat-run tests, PLECS thermal simulation based loss comparison and MV experiments on developed hardware prototypes. The impact of switching frequency on the harmonic control of the grid connected converter is also discussed and suitable device is selected for better grid current THD. 8:55AM Comparison between SiC and GaN devices in 6.78 MHz 2.2 kW resonant inverters for wireless power transfer [#807]
This paper presents a performance comparison of two wide band gap (WBG) devices, a silicon carbide (SiC) MOSFET and an enhancement mode gallium nitride (eGaN) FET in a resonant inverter operating at 6.78 MHz for wireless power transfer (WPT) applications. While SiC MOSFETs provide high breakdown voltage and good thermal characteristics, eGaN FETs can reduce gate losses due to small gate resistance and input capacitance. In this work, we compare a 1200 V SiC MOSFET in a single-ended class Phi2 inverter to two 650 V eGaN FETs in a push-pull class Phi2 inverter. We designed and implemented a 6.78 MHz 2.2 kW single-ended class Phi2 inverter using a 1200 V customized SiC MOSFET with low-inductance package. In our experiments, the inverter has a 93% efficiency and 2.2 kW output power with input voltage of 440 V. We also implemented a push-pull class Phi2 inverter using a 650 V eGaN FET at 6.78 MHz. The push-pull class Phi2 inverter reduces the input current ripple because of interleaving operation. At 200 V input voltage, the push-pull inverter with two eGaN FETs provides output power of 2 kW with 96% efficiency. In order to reduce a volume and weight of the inverter, we implemented a class Phi2 inverter with 3D printed inductors. 9:20AM Comparison of GaN FET and Si MOSFET Based Vienna Rectifiers [#1390]
As the technology on wide bandgap materials such as gallium-nitride (GaN) has advanced rapidly, commercial GaN power devices with satisfying performance are available now. It is widely-known that GaN-based switching devices have several advantages over traditional Si-based switching devices, such as lower ON-resistance, faster switching speed, better thermal conductivity, and smaller size. However, researchers have not yet fully explored and applied GaN devices in some of the important power conversion applications. In this paper, a popular three-phase three- level three-switch Vienna rectifier is designed with GaN FETs. The advantages and challenges of utilizing GaN FETs in Vienna rectifiers are discussed. The topology, control and simulation are carried out as well. To provide a comparative analysis of the GaN FET and Si MOSFET based Vienna rectifiers, two prototypes are built with each type of the power devices on a similar scale. Detailed comparative analysis discussions based on the experimental results, including size, power circuit efficiency and THD, are provided. It is concluded in this paper that GaN FETs and their drivers have smaller size and higher power density compared with Si MOSFETs and their drivers. The overall performance of the GaN FET and Si MOSFET based Vienna rectifiers are at the same level, although driving techniques of the GaN FET devices are not mature. 9:45AM Comparison of GaN and SiC Power Devices in Application to MW-scale Quasi-Z-Source Cascaded Multilevel Inverters [#835]
Wide bandgap (WBG)semiconductors including gallium nitride (GaN) and silicon carbide (SiC)offer significant performance improvement compared with conventional silicon power devices. The quasi-Z-source cascaded multilevel inverter (qZS-CMI)provides many advantages over the conventional CMI while applied in photovoltaic (PV) systems. In this paper, two solutions are proposed and compared for the design goal of a high efficiency and low cost qZS-CMI based 1 MW/11 kV PV system. The first solution is based on 650 V GaN enhancement mode high-electron-mobility transistors (E-HEMT) and 650 V SiC Schottky diodes. The second solution uses 1200 V SiC power modules and 1200 V SiC Schottky diodes. The power losses and costs of the two candidate designs are compared in details. It is concluded that the first solution shows lower power losses and costs per quasi-Z-source inverter (qZSI) module. However, due to low voltage rating of GaN E-HEMTs, more qZSI modules are needed to achieve the overall 11kV inverter rating. Therefore, the second solution shows lower total power loss and cost in the medium-voltage, MW-scale qZS-CMI PV system. 10:10AM Comparison of deadtime effects on the performance of dc-dc converters with GaN FETs and Silicon MOSFETs [#231]
Switching loss is an important and often the dominant source of converter losses. While soft-switching can greatly reduce the impact of switching loss, hard-switching is often preferred due to the simplicity of design, control, and implementation. Wide bandgap (WBG) semiconductors such as gallium nitride (GaN) and silicon carbide (SiC) have greatly reduced switching losses due to faster transition speeds, reduced output capacitance and reduction or elimination of reverse recovery. However, the high reverse voltage drop during deadtime and resulting conduction loss of WBG devices has led to the belief that deadtime management is more important than for silicon MOSFETs. This paper quantifies the effects of output capacitance, reverse recovery, and deadtime. It highlights the relationship between deadtime and reverse recovery, and provides experimental results showing that silicon MOSFETs can show far greater losses than GaN as a result of poor deadtime management. 10:35AM Characterization and Comparison of Latest Generation 900-V and 1.2-kV SiC MOSFETs [#1581]
This paper performs static and dynamic performance characterization of latest generation 900-V and 1.2-kV discrete Silicon Carbide (SiC) MOSFETs from four well-known manufacturers: CREE, ROHM, General Electric (GE) and Sumitomo Electric Industries (SEI). The static characterization performed includes acquisition of output characteristics, transfer characteristics, specific on- state resistances, threshold voltages and junction capacitances of the devices under test (DUTs). The static characterizations are done from 25C up to 150C to investigate variation of parameters versus temperature. At the other hand and for dynamic characterization, following a double-pulse tester design the tests are done at four different temperatures on all devices: 25C, 100C, 150C and 200C. In dynamic test, recommended gate voltages are applied to all devices and the switching speeds are matched. The switching losses are computed from double-pulse test (DPT) results. Gate Drive Techniques I Tuesday, September 20, 8:30AM-11:00AM, Room: 102A, Chair: Prasad Enjeti, Daniel Costinett 8:30AM High Speed Optical Gate Driver for Wide Band Gap Power Transistors [#435] Davy Colin and Nicolas Rouger, Grenoble Electrical Engineering Laboratory, France This paper presents the design of a CMOS gate driver fabricated in 0.18 um technology. Optical receivers are integrated to provide the highest dV/dt immunity. A configurable buffer with 7A current capability is also integrated. Two solutions of optical receivers and gate signal transfer are introduced. In both cases a particular attention is addressed to the delays and delay mismatches for high frequency converter applications. The effects of temperature, supply voltage and input photocurrent amplitude are investigated. Delay mismatches <5ns are expected. This CMOS gate driver has shown by experiments high switching frequency operation (typically 1.5 MHz) with low overall propagation delays (<25ns). 8:55AM Reduction of oscillations in a GaN bridge leg using active gate driving with sub-ns resolution, arbitrary gate-impedance patterns [#667]
Active gate driving provides an opportunity to reduce EMI in power electronic circuits. Whilst it has been demonstrated for MOS-gated silicon power semiconductor devices, reported advanced gate driving in wide-bandgap devices has been limited to a single impedance change during the device switching transitions. For the first time, this paper shows multi-point gate signal profiling at the sub-ns resolution required for GaN devices. A high-speed, programmable active gate driver is implemented with an integrated high-speed memory and output stage to realise arbitrary gate pull-up and pulldown resistance profiles. The nominal resistance range is 120 mO to 64 O, and the timing resolution of impedance changes is 150 ps. This driver is used in a 1 MHz GaN bridge leg that represents a synchronous buck converter. It is demonstrated that the gate voltage profile can be manipulated aggressively in nanosecond scale. It is observed that by profiling the first 5 ns of the control device’s gate voltage transient, a reduction in switch-node voltage oscillations is observed, resulting in an 8-16 dB reduction in spectral power between 400 MHz and 1.8 GHz. This occurs without an increase in switching loss. A small increase in spectral power is seen below 320 MHz. As a baseline for comparison, the GaN bridge leg is operated with a fixed gate drive strength. It is concluded that p-type gate GaN HFETs are actively controllable, and that EMI can be reduced without increasing switching loss. 9:20AM Design Considerations and Comparison of High-speed Gate Drivers for Si IGBT and SiC MOSFET Modules [#1220]
The high switching frequency (> 20 kHz) of SiC MOSFET module makes it as an attractive alternative of Si IGBT module for high power density applications. Since SiC MOSFET and Si IGBT have the similar MOS-gated structure, it is normally regarded that the gate driver of SiC MOSFET can directly inherit from that of Si IGBT. However, considering the different device physics properties, some special design considerations need to be taken. In addition, the higher dv=dt and di=dt in SiC MOSFET module leads to more serious EMI issues, which will comprise the switching speed in return. In this work, the high-speed gate drivers for Si IGBT and SiC MOSFET modules with similar ratings are designed and optimized. Based on the experiment of switching characterization, the considerations of gate driver design to migrate from Si IGBT module to SiC MOSFET module are presented. And the EMI issue is the major challenge in the gate driver design for SiC MOSFET module. 9:45AM Active Gate Driving Technique for a 1200 V SiC MOSFET to Minimize Detrimental Effects of Parasitic Inductance in the Converter Layout [#1432]
A 1200 V SiC MOSFET switches at much faster rate compared to a Si IGBT. As a consequence, SiC MOSFET experiences comparatively more ringing in device voltage and current due to the presence of parasitic inductance in the converter layout. Therefore, it is not straightforward to retrofit SiC MOSFETs in the converter layout of IGBTs where parasitic inductance appears in the range of 100 nH to 300 nH. This paper proposes an active gate driving technique for SiC MOSFET to improve overall switching performance in the presence of parasitic inductance. The proposed driver allows SiC MOSFET to switch almost at its normal speed with relatively large amount of parasitic inductance in the layout (100 nH to 300 nH). The device voltage and current stresses are also controlled. The developed active gate driver is tested in a double pulse test bed. The performance of the active gate driver is also tested in a 10 kVA two level inverter driving an induction motor load. 10:10AM Comprehensive Evaluation of Gate Boost Driver for SiC-MOSFETs [#122]
This paper presents fast, low loss, and low noise gate driver for Silicon- Carbide (SiC) MOSFETs. We proposed gate boost circuit to reduce switching losses and switching delay time without increasing switching noise. The proposed gate driver makes it possible to improve converters efficiency or enhance power density of converters. SiC power devices have attracted huge interest as next generation power devices. Normally, switching performances of power devices have trade-off between switching losses and switching noise. SiC- MOSFETs are expected to be able to switch faster than Silicon IGBTs, but faster switching might cause switching noise problem such as electromagnetic interferences (EMI). We proposed the gate boost circuit to improve switching performances of SiC-MOSFETs, and also confirmed that the proposed gate driver reduce switching losses and delay time with experimental results. 10:35AM Gate Driver for the Active Thermal Control of a DCDC GaN based Converter [#1028]
Wide-Band-Gap power semiconductors based on SiC and GaN offer some significant advantages compared to Si-devices, in particular higher switching speed and higher operating temperature. These features offer potentially increased power density, which makes the temperature management critical especially for the PCB and components to which the GaN is connected. In this paper, an active gate driver with active thermal control is implemented and can be used to alter the losses of a DC/DC buck converter based on GaN transistors, with the aim of reducing the thermal cycling thus improving the converter's lifetime. Wireless Power Transfer II Tuesday, September 20, 8:30AM-11:00AM, Room: 202B, Chair: Khurram Afridi, Huai Wang 8:30AM A Mistuning-Tolerant and Controllable Power Supply for Roadway Wireless Power Systems [#593] Abhilash Kamineni, Grant A. Covic and John T. Boys, The University of Auckland, New Zealand Inductive Power Transfer power supplies for electric vehicles (EV) charging in dynamic applications need to tolerate large variations in coupling and tuning with varying loads. This paper investigates the use of a buck converter to regulate the input voltage to a fixed frequency unidirectional switch push-pull converter to meet the requirements of dynamic charging. The presented circuit is optimised to remove some of the additional components introduced. A mathematical model is presented which shows the circuit is capable of operating while extremely mistuned in both the inductive and capacitive regions while maintaining low THD. A controller design is also presented allowing constant primary current operation, safe start up and operation under no load conditions. The results from a 1 kW prototype tolerating a 34% change in primary inductance is also presented. 8:55AM Power Converter with Novel Transformer Structure for Wireless Power Transfer Using a DD2Q Power Receiver Coil Set [#878]
In an Inductive Power Transfer (IPT) system, the magnetic design of the primary and secondary pads is an important factor that determines the power transfer capability. This paper proposes a DD2Q power receiver coil set, a novel three coil magnetic pad that comprises a classical DD winding and two additional quadrature windings placed at the secondary side (referred to as 2Q). The DD2Q coil set achieves tolerance to larger lateral displacements and rotational displacements than conventional DD pads. A 100 W contactless energy transmission system using the proposed transformer is tested.
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