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:
- Fault Prognosis for Power Devices
- Thermal Analyses of Electric Machines
- Transverse Flux Machines
- Control of Electric Drives II
- Power Packaging
| 9:45AM An online measurement method for common-mode impedance in three-phase grid-connected converters [#557]
Tuomas Messo, Tomi Roinila, Jukka Viinamaki and Teuvo Suntio, Tampere University of Technology, Finland A typical three-phase two-level converter produces high frequency common-mode voltage when sinusoidal PWM is used. Common-mode currents are produced which depend on the magnitude of common-mode impedance seen by the inverter. This paper proposes a method to measure the common-mode impedance seen by the inverter online by utilizing a SiC-inverter. Fault Prognosis for Power Devices Thursday, September 22, 8:30AM-10:10AM, Room: 102E, Chair: Marco Liserre, Juan Rivas-Davila 8:30AM Remaining Useful Lifetime Estimation For Thermally Aged Power Mosfets With Ransac Denoising Algorithm [#1442] Serkan Dusmez, Mehrdad Heydarzadeh, Mehrdad Nourani and Bilal Akin, University of Texas at Dallas, United States This paper focuses on the remaining useful lifetime (RUL) estimation of power MOSFETs, which are stressed by thermal cycling. The relative change in on-state resistance is identified as the aging precursor for die attach solder degradation after exhaustive experiments. A data-driven RUL estimation algorithm based on a linear approximation model is proposed. The empirical coefficients are estimated by the classical least squares method. However, the initial part of the data contains a significant number of outliers, which decreases the estimation accuracy. In order to remove the outlier effect and make the estimation robust, least-squares method is applied to only inliers that are determined by random sample consensus (RANSAC) algorithm. With the exclusion of outliers, the RUL estimation is improved for the ones that contain outliers. The accuracy of the proposed RUL estimation tool is verified on a number of thermally aged discrete power MOSFET data 8:55AM An Analytical Model for False Turn-On Evaluation of GaN Transistor in Bridge-Leg Configuration [#566]
Gallium Nitride (GaN) transistors are especially attractive in their capability of switching at high frequencies, and enable power conversion systems with reduced size and higher efficiency. However, owing to the low threshold voltage of the commercially available enhancement-mode (E-mode) GaN devices, the devices are more prone to false turn-on phenomenon, leading to larger switching losses, circuit oscillation and even shoot-through in bridge-leg configuration. In order to enlarge the gate terminal's safe operating margin without increasing the reverse conduction loss during dead-time, a negative gate voltage bias for turn- off and an anti-parallel diode can be applied to GaN transistor. In this work, to accurately evaluate the detailed turn-on characteristics of GaN transistors in bridge-leg configuration,analytical device models that count for the strong nonlinearities of device's I-V and C-V characteristics are firstly developed. Then an analytical circuit model taking into account the circuit parameters as well as the intrinsic behaviors of GaN transistor and anti-parallel diode is established. Thus, the critical transient waveforms, such as displacement currents and false triggering voltage pulse on gate terminal can be simulated. The proposed models are then verified on a testing board with GaN-based bridge- leg circuit. To provide design guidelines for suppressing false turn-on, impacts of circuit parameters are investigated based on the proposed model. 9:20AM Advanced Condition Monitoring System Based on On-Line Semiconductor Loss Measurements [#1105]
This paper presents an FPGA-based on-line condition monitoring system integrated at gate-driver voltage level. The system uses the change of on-state voltage and thermal resistance as ageing indicators. The monitoring is realized by implementing an on-line semiconductor power loss measurement system for switching and on-state losses and a thermal model of the module. Apart from the concept, its practical implementation is described, and the experimental results are given. 9:45AM A Comprehensive Study on Variations of Discrete IGBT Characteristics Due to Package Degradation Triggered by Thermal Stress [#620]
Identification of power device failure precursors is essential for condition monitoring, fault severity assessment and lifetime estimation. These tools constitute the fundamental elements to achieve highly reliable power converters with self-diagnosis capability, which can report incipient faults at very early stage. In this paper, several discrete IGBTs are thermally aged on a custom-built modular test-bed. I-V characteristics are monitored periodically using an automated curve tracer throughout the aging, and the fault/aging related patterns are comprehensively analyzed. The variations in saturation voltage, gate threshold voltage, transfer capacitances, and gate charge, which are the potential candidates for aging precursors, are analyzed in detail. The experimental and failure analysis results suggest that on-state voltage drop and gate threshold voltage are the two essential aging precursors for monitoring die- attach solder and gate oxide degradations. Thermal Analyses of Electric Machines Thursday, September 22, 8:30AM-10:10AM, Room: 102B, Chair: Bulent Sarlioglu, Patel Bhageerath Reddy 8:30AM Experimental Calibration in Thermal Analysis of PM Electrical Machines [#644] Sabrina Ayat, Rafal Wrobel, James Goss and David Drury, University of Bristol, Motor Design Ltd, United Kingdom; Motor Design Ltd, United Kingdom; University of Bristol, United Kingdom Thermal design of electric machines frequently involves tests on a fully constructed prototype to calibrate various build factors associated with the manufacture, assembly and materials used in the hardware construction. The prototype machine is usually instrumented with multiple temperature sensors providing a detailed insight into the temperature distribution. The resolution of the experimentally gathered data is usually limited by the number of temperature sensors, and therefore the quality of model calibration is highly affected by the input data. This paper investigates the issue of thermal model calibration in the context of available machine hardware and measured data resolution. Also, the research evaluates the most suitable thermocouple location with reference to the model complexity, from reduced-order lumped-parameters circuit to high-fidelity finite element method (FEM). The investigation is focused on the stator-winding assembly, which is frequently associated with the main source of power loss within a PM machine body. A prototype of a PM generator has been selected to illustrate the effects associated with the model calibration. Tests on a representative stator-winding sub-assembly (motorette) have been used in the analysis. The results suggest that the measured data from alternative sensor locations for a given machine region has a significant impact on the quality of the model calibration and consequently temperature predictions. 8:55AM Thermal Conductivity Evaluation of Fractional-Slot Concentrated-Winding Machines [#11]
The use of Fractional-Slot Concentrated Windings (FSCW) in electrical machines allows more compact, efficient and reliable design with respect to machines equipped with distributed windings. However, an electromagnetic design linked to a thermal analysis of the electrical machine is mandatory to achieve the desired performance and to fulfill the requirements of efficiency and reliability. One of the most critical issues in thermal design of electrical machines is to assign fair values for the input parameters of the thermal simulation models, particularly those related to the stator winding insulation system. This paper deals with the assessment of the equivalent thermal conductivity of the insulation system of FSCW machines. For this purpose, three FSCW electrical machines for different applications were evaluated via an experimental method based on a dc thermal transient test. Whereas the investigated machines present different characteristics among themselves, different approaches were required to properly estimate the thermal conductivity. 9:20AM Thermal Performance Modeling of Foil Wound Concentrated Coils in Electric Machines [#1449]
While the use of foil windings in transformers and air core inductors is not uncommon, their use in electric machines is just emerging. Although prototype realizations have been reported in the literature, a definitive analysis of their thermal performance is necessary to evaluate their potential for broad applications. This paper is devoted to presenting a comprehensive model for evaluating their thermal performance including loss modeling and temperature rise prediction in realistic designs. An overview of foil windings in electric machines and their advantages in improved fill factor is presented, along with experimental results that compare the AC losses and temperature distribution under identical steady-state operating conditions with a prototype round conductor coil and foil conductor coil. A lumped parameter thermal model that predicts the heat transfer behavior of the foil conductor coil is presented along with supporting experimental results. 9:45AM Experimental Validation in Operative Conditions of Winding Thermal Model for Short-Time Transient [#17]
This paper presents the validation of a first-order winding thermal model in machine operative conditions. The proposed model can be used in motor control strategies for the winding temperature prediction during transient overload or vice versa, for the prediction of the maximum time duration of the overload maintaining the winding temperature within the limit imposed by the class of insulation. The thermal model has been validated using two different electrical machines. The first one is a 10 kW automotive starter- generator prototype for mini-hybrid powertrain equipped with distributed bar windings, while the second one is a 2.2 kW total enclosed fan cooled industrial induction motor equipped with conventional stranded wire windings. To both machines it is mainly required a short-duty transient operation in overload conditions. In particular, the automotive starter-generator must accomplish the engine cranking and torque assistance during the vehicle acceleration and braking, while the considered industrial induction machine has to operate in intermittent service in overload conditions for machine tool applications. As a consequence, an accurate stator winding temperature prediction is mandatory to fully exploit the machine performance. For both motors, the thermal model parameters have been evaluated by fast experimental approach and subsequently, the model has been validated during operative overload conditions. Transverse Flux Machines Thursday, September 22, 8:30AM-10:10AM, Room: 101A, Chair: Keith Corzine, Daniel Ludois 8:30AM A Hybrid-Excited Axial Transverse Flux Permanent Magnet Machine [#1311] Emrullah Aydin, Ju Hyung Kim, Emin Yildiriz, Mehmet Timur Aydemir and Bulent Sarlioglu, Electrical-Electronic Engineering, Gazi Univ., Turkey; Electrical and Computer Engineering, UW-Madison, United States; Electrical-Electronic Engineering, Duzce Univ., Turkey This paper proposes a modular hybrid-excited axial transverse flux permanent magnet machine. The operational principles and performance characterization are presented. The toroidal excitation windings are placed on both teeth of the U-type core and are excited by a field current. The field current can either buck or boost the magnetic flux produced by the circular permanent magnets on the rotor disk. The finite element analysis is performed to quantify the change in flux linkage, back-EMF, and output power as a function of field current. This research contributes to the field weakening or intensifying feature of the axial transverse flux PM machine. 8:55AM Reduction of Cogging Torque in Transverse Flux Machines by Stator and Rotor Pole Shaping [#396]
This paper presents a method of reducing the cogging torque of transverse flux machines by shaping the poles of the rotor. A number of different techniques are presented and simulated. These simulations are verified by the construction of a number of rotors from which measured results have been obtained. Further to this, the rotors are applied to machines with different cogging torque reduction techniques applied to the stator. Measurements of cogging torque have been taken in order to assess the overall effectiveness of each technique. 9:20AM Design Considerations of a Transverse Flux Machine for Direct Drive Wind Turbine Applications [#1288]
This paper presents the design considerations of a double-sided transverse flux machine (TFM) for direct-drive wind turbine applications. The TFM has a modular structure with quasi-U stator cores and ring windings. The rotor is constructed with ferrite magnets in a flux-concentrating arrangement to achieve high air gap flux density. The design considerations for this TFM with respect to initial sizing, pole number selection, key design ratios, and pole shaping are presented in this paper. Pole number selection is critical in the design process of a TFM because it affects both the torque density and power factor under fixed magnetic and changing electrical loading. Several key design ratios are introduced to facilitate the design procedure. The effect of pole shaping on back-emf and inductance is also analyzed. These investigations provide guidance toward the required design of a TFM for direct-drive applications. The analyses are carried out using analytical and three-dimensional finite element analysis. A prototype is under construction for experimental verification. 9:45AM Analytical Model Based Design Optimization of a Transverse Flux Machine [#1299]
This paper proposes an analytical machine design tool using magnetic equivalent circuit (MEC)-based particle swarm optimization (PSO) for a double-sided, flux- concentrating transverse flux machine (TFM). The magnetic equivalent circuit method is applied to analytically establish the relationship between the design objective and the input variables of prospective TFM designs. This is computationally less intensive and more time efficient than finite element solvers. A PSO algorithm is then used to design a machine with the highest torque density within the specified power range along with some geometric design constraints. The stator pole length, magnet length, and rotor thickness are the variables that define the optimization search space. Finite element analysis (FEA) was carried out to verify the performance of the MEC-PSO optimized machine. The proposed analytical design tool helps save computation time by at least 50% when compared to commercial FEA-based optimization programs, with results found to be in agreement with less than 5% error. Control of Electric Drives II Thursday, September 22, 8:30AM-10:10AM, Room: 101CD, Chair: Marko Hinkkanen, Pinjia Zhang 8:30AM A Novel Six-Phase Inverter System for High-Power Synchronous Motor Drives [#494] Yumei Song, Xiaojie You, Xizheng Guo and Jian Wang, Beijing Jiaotong University, China Load commutated inverters with multiple three-phase configurations are widely used in high-power synchronous motor drives due to its robustness and reliability. However, harmonic problems, poor starting performance and the limited upper frequency are the issues to be addressed. In this paper, a novel six-phase inverter system, consisting of two main three-phase inverters and an additional five-level reinjection circuit, is proposed. The reinjection circuit which generates five current steps is introduced in this study. To note, the lowest current level is zero to ensure the zero current switching of the main inverters. Therefore, the starting performance and torque quality of the synchronous motor are greatly improved. Moreover, the limit of upper frequency is raised since the mutual interaction between stator windings is eliminated during commutation. 8:55AM State-Space Flux-Linkage Control of Bearingless Synchronous Reluctance Motors [#388]
This paper deals with a model-based state-space flux-linkage control of a dual three-phase-winding bearingless synchronous reluctance motor. Analytical tuning rules for the state feedback, integral action, and reference feedforward gains are derived in the continuous-time domain. The proposed method is easy to apply: the desired closed-loop bandwidth together with the estimated magnetic-model of the motor are required. Furthermore, the proposed method automatically takes into account the mutual coupling between the two windings. A simple digital implementation is provided and the robustness of the proposed control method against the system parameter inaccuracies and eccentric rotor positions is analyzed. The proposed controller design is evaluated by means of simulations by keeping in mind the most important aspects related to an experimental evaluation. 9:20AM Current Harmonic Compensation for n-Phase Machines With Asymmetrical Winding Arrangement [#639]
Multiphase machines (MPMs) have become serious contenders in several applications, such as offshore wind energy and electric vehicles. Low-order current harmonics arise in actual drives due to converter and machine nonlinearities, thus producing losses and torque ripple. In comparison to threephase machines, in MPMs this effect is aggravated because of the existence of low-impedance subspaces. To cancel these harmonics, a multiple resonant controller (RC) (MRC) structure has recently been proposed for MPMs, which combines RCs and synchronous frames (SFs). The MRC scheme allows a significant computational saving in comparison to the multiple SF (MSF) strategy, which includes a proportional-integral controller in an SF per each harmonic. However, such MRC method is only suitable for MPMs with symmetrical winding arrangement (SWA), while asymmetrical winding arrangement (AWA) is also a common choice. In this paper, the MRC strategy is extended to MPMs with AWA. Different neutral configurations, whose effect on the harmonic mapping is more complicated than for SWAs and has hardly been studied so far, are considered. The optimum combinations of frequencies at which the RCs and the SFs should be tuned for AWAs are assessed. Simulation results are provided. 9:45AM Post-fault operation strategy for single switch open circuit faults in electric drives [#1316]
Single switch open circuit faults in three-phase AC drives lead to undesired effects and potentially to a total failure of the drive. This paper proposes a post-fault operation strategy for such faults with the focus on the limitation of losses after the reconfiguration and thereby an extension of the possible range of operation. The performance of the strategy is shown both via simulations and experiments. Power Packaging Thursday, September 22, 8:30AM-10:10AM, Room: 202C, Chair: Douglas C Hopkins, Giuseppe Chimento 8:30AM A Quasi-online Method of Thermal Network Parameter Identification of IGBT Module [#385] Tengfet Li, Xiong Du, Cheng Zeng, Pengju Sun and Heng-Ming Tai, Chongqing University, China; University of Tulsa, United States The previous proposed method for thermal network parameter identification of IGBT module in [1] is based on the pre-knowledge of heat sink's thermal parameter, which neglected the aging effect of heat sink. This paper improved the identification method in [1]and make the improved method be applicable to systems without acknowledge of heat sink's thermal parameter. The theoretical analysis got the relationship between the thermal network parameter and the time constants of junction temperature when cooling down. We show that the thermal network parameters can be identified in three different cooling conditions. Furthermore, some experiments on an IGBT module were tested and discussed. The obtained RC parameters are in good agreement with the results by JESD51-14 method. The proposed method is based on the information of junction temperature when cooling off. Moreover, the cooling curve of junction temperature can be obtained when the IGBT is out of working, which real exists in some converters. Therefore, the proposed method can be applied in quasi-online. 8:55AM Direct-cooled power module with a thick Cu heat spreader featuring a stress-suppressed structure for EV/HEV inverters [#350]
This paper presents direct-cooled power module technologies that satisfy the requirements for lower thermal resistance and stress relaxation, especially for small die size semiconductors (e.g. Silicon Carbide (SiC)). The power module structure features a thick Copper (Cu) heat spreader located under the semiconductor chip for lower thermal resistance and a thin closed Aluminum (Al) water jacket for stress relaxation. And a prototype power module was fabricated using a thick Cu heat spreader that reduces thermal resistance by 34% compared with conventional direct-cooled power modules. It was also shown that using a thin closed Al water jacket (multi-port tube) achieves the same level of stress as conventional power modules, thereby mitigating the stress-strain and solder cracking induced by the metal junctions with a thick Cu structure.
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