Table of contents monday, September 9, 1: 30pm-4: 00pm modular Multi-Level Converters, hvdc, and dc grids I 3
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- Poster Session: Electrical Machines
| P911 Error-Voltage Based Open-Switch Fault Diagnosis Strategy for Matrix Converters with Model Predictive Control Method [#323]
Hui Deng, Tao Peng, Hanbing Dan, Mei Su and Jingrong Yu, Central South University, Jiangxi Kangcheng Co., China This paper proposes an error-voltage based open-switch fault diagnosis strategy for matrix converter (MC). First, finite control set-model predictive control (FCS-MPC) method is used to operate the MC. Meanwhile, based on the analysis of the operating state under fault condition, the fault model of MC is established. Second, the fault diagnosis strategy is implemented in three steps: to begin with, the occurrence of fault is detected by monitoring the measured load currents. Then, the faulty phase is identified considering the output line-to-line voltage error. After that, by using the switching state of the faulty phase, the faulty switch is located. The fault diagnosis method can accurately and quickly locate the faulty switch without additional voltage sensors. Finally, simulation results are presented to demonstrate the feasibility and effectiveness of the proposed strategy. P912 Instrumented Diode Dedicated to Semiconductor Temperature Measurement in Power Electronic Converters [#496]
Temperature measurement of semiconductor components is essential, in particular to evaluate performances and to propose health monitoring of power modules. ThermoSensitive Electrical Parameters (TSEPs) are widely used to estimate a representative temperature of these components, mainly in non-operating conditions, different from the real environment of the latter (offline measurements). Nevertheless, some TSEPs may be adapted to online temperature measurements, in operating conditions of power converters. It is however difficult to evaluate the accuracy of those TSEPs. This paper presents an instrumented chip dedicated to estimate the temperature in power electronic modules under functional constraints. Thus, it offers a reliable and robust tool for temperature measurements in power electronic converters. Preliminary results presented in this paper concern the technological process of realization and demonstrate the good functioning of this instrumented chip under power dissipation and switching conditions. P913 Reliability Odometer of Power Semiconductor Device Used for high performance high power amplifiers [#1240]
This paper presents a real-time evaluation of power semiconductor devices in a high performance high power amplifier. The proposed method can represent the life status of the semiconductor modules in odometer format. A special challenging case are pulsating load applications like an MRI gradient driver system. The general concepts presented have been evaluated in detail for the MRI case. A detailed Cauer thermal network is proposed to estimate the temperature from junction to ambient with the combination of non-ideal heatsink. Rainflow counting method and Palmgren-Miner linear damage accumulation rule are introduced and designed for the on-line cycle counting and real-time lifetime consumption estimation. The paper explains the design of the method considerations to minimize the computing time and memory requirements different from standard off line or post analysis approaches. Simulation models and hardware prototype are built to validate the design and analysis. P914 Energy and Computational Efficient Estimation of Battery Intrinsic Parameters [#1366]
This paper presents an efficient battery parameter extraction technique with energy recycling feature. Based on transferring the testing energy to and from a supercapacitor (storage device) through a bidirectional DC-DC converter, the charging and discharging current profile of a battery can be obtained for analyzing the battery characteristics and parameters extraction. With the testing energy stored in a supercapacitor, the concern of thermal management is eliminated. By applying a newly modified efficient particle swarm optimization algorithm, the voltage and current data are used to estimate the intrinsic parameters of a high-order electrical battery model. A prototype has been implemented for extracting the intrinsic parameters of four different types of 12V lead-acid battery, and with evaluation current evaluated up to 150A. The estimated parameters have been verified against the theoretical predictions as well as the test results obtained from the NHR battery testing system. P915 Snubber Capacitors Optimization for Super-Junction MOSFET in the ZVS Full-Bridge Inverter [#530]
A zero voltage switching full-bridge inverter and its modulation schemes have been investigated in previous literatures. Parallel snubber capacitors are utilized to reduce the turn off loss of super unction MOSFETs in the ZVS full bridge inverter. However due to the MOSFET's nonlinear output capacitance the ZVS commutation is unable to be realized and high voltage spike occurs on switching devices under light load condition. The problem is solved by changing the position of the snubber capacitors. Poster Session: Electrical Machines Monday, September 19, 5:30PM-7:00PM, Room: Exhibit Hall, Chair: Bruno Lequesne, Mohammad Islam P1101 A Computational Technique for Iron Losses in Electrical Machines [#450] Omar Bottesi, Luigi Alberti, Ruth V. Sabariego and Johan Gyselinck, Free University of Bozen-Bolzano, Italy; Katholieke Universiteit Leuven (KU Leuven), Belgium; Universite Libre de Bruxelles (ULB), Belgium This paper aims to compare different methods for the computation of the iron losses. First of all, a brief recall on iron losses models is considered. In particular, Bertotti's formula, a homogenization technique and a vectorized Jiles-Atherton model are implemented. Afterwards, the adopted methods are validated considering an iron ring and an inset PM synchronous machine. A comparison between experimental measurements on the iron ring and the adopted methods is presented. The inset PM synchronous machine is simulated in different operating conditions: both at standstill and no load. Good agreement has been found between the results. P1102 Saliency Harmonic Induction Motor Speed Estimation Using Artificial Neural Networks [#34]
Several methods have been proposed to measure the speed of an induction machine without the need for external speed transducers. These sensorless methods typically use observers, require injected signals, or are dependent on the detecting a specific harmonic. This paper investigates using neural networks to identify the speed of a machine using a range of harmonics without specific knowledge of machine parameters. As a proof of concept currents measured from various machines are analyzed with the proposed method. This analysis showed that such a system has the potential for relatively accurate speed determination. P1103 Reclosing Transients in Standard and Premium Efficiency Induction Machines in the Presence of Voltage Unbalance [#241]
The impact of restarting an induction machine, while coasting, is investigated in this paper. When restarting a motor, high peaking currents and torque transients appear. As a result, possible damage to the rotor shaft could occur together with destabilising the power system which could lead to a fluctuating supply voltage levels. This paper investigates the restarting of two different efficiency class induction machines and analyses how a shift in phase between the supply and residual voltage affects the restarting transients. Previous studies have been carried out on standard efficiency induction machines (SEIM), however this paper aims to compare the impact of restarting on the standard and premium efficiency induction machines (PPEIM). A further contribution is made by studying the impact of restarting these machines in the presence of voltage unbalance. P1104 Parameter sensitivity of large electric machines [#22]
Machine simulation models allow the use of embedded numerical computation techniques. The numerical model and computational accuracy is usually gauged by comparison with experimental measurements. In this paper a large hydro generator is modeled and the sensitivity of various model parameters is investigated by comparing the simulated results with experimental measurements from four units of the same design. The machine open circuit voltage was found to be very sensitive to the airgap and stator B-H curve. Moreover, for 2D simulations the effective length is also important because it should account for differences in the stator and rotor lengths, in addition to the presence of radial air ducts. A 20% variation in operation airgap between two machines of the same design induced over 18% difference in open circuit voltage. Reduction in permeability of the soft magnetic materials resulted in agreement between the numerical and measured results at saturation. Consequently for large machines, the B-H curves from the Epstein measurements are insufficient and should be adjusted accordingly. P1105 Optimal Winding Arrangement of a Surface-Mounted Permanent Magnet Motor for Torque Ripple Reduction [#84]
We are aiming to develop a high precision micro-milling machine with a high speed spindle which is driven by a permanent magnet motor and supported by active magnetic bearings. The torque ripple, however, may have influence on the positioning accuracy. As a first step of this study, we investigate torque ripple reduction of a permanent magnet motor. This paper considers optimal winding arrangement of a 2-pole/12-slot surface permanent magnet motor with double-layer distributed winding to minimize magnet torque ripple. The magnet torque with double-layer winding is theoretically derived by considering the spatial harmonics of the MMF distribution. The torque ripple with 6wt variation is theoretically zero when the ratio of the secondary winding with respect to the primary one is about 0.37. In addition, the PM step skew is investigated to reduce the cogging torque, based on three-dimensional finite element method analysis. The experimental results demonstrate that the optimal double-layer winding configuration with the winding ratio of 0.37 is effective to reduce the magnet torque ripple. P1106 Numerical Study of Convective Heat Transfer in the End Region of A Totally Enclosed Permanent Magnet Synchronous Machine [#126]
This paper proposes a numerical approach for the determination of convective heat transfer coefficients in the end region of a totally enclosed permanent magnet synchronous machine used as an integrated starter generator in a hybrid vehicle. A simplified numerical model based on CFD methods is developed to understand the mechanism of convective heat transfer over a large operation range. The effect of the rotation speed on the variation of the convective heat transfer coefficients inside the end region is thoroughly investigated. Heat flux paths are also identified for the entire operating range. P1107 Torque Improvement of Wound Field Synchronous Motor for Electric Vehicle by PM-assist [#279]
In order to improve the performance of the wound field synchronous motor (WFSM), the permanent magnet assist (PM-assist) is investigated in this paper. The effect of the permanent magnet assist is dependent on the inserted position of the permanent magnets. Thus, four models whose permanent magnets are inserted at each different positions are suggested. Then, the most effective position of the permanent magnet is decided by the mean torque per employed amount of the permanent magnet. By inserting the permanent magnets into the decided position of a WFSM designed for a small electric vehicle traction, the PM-assisted WFSM is designed. By comparing the torque and the efficiency of the original WFSM and the PMassisted WFSM, the effectiveness of the PM-assist is figured out. Finally, the validity of this research is verified by the experiment using the manufactured WFSM. P1108 Torque Ripple Reduction of a Variable Flux Motor [#32]
This paper examines torque ripple in a new topology of variable flux machine with AlNiCo magnet. To reduce the torque ripple, the design and finite element modeling of this machine are reviewed and the finite element model results are verified with the prototyped motor. The effects of various electrical, magnetic and geometrical parameters such as load, magnetization level of the magnet, tooth and yoke width and magnet dimensions, on both torque mean value and torque ripple are discussed using the verified finite element model. Finally, modified rotor structure is presented that reduces the torque ripple by 35% with the same torque mean value and magnetization current for the motor. The torque ripple of the modified design is analyzed for a wide range of load and speed. P1109 An Analytical Model for a Spoke Type Variable Flux Permanent Magnet Motor on No-load Condition [#33]
This paper presents an analytical model, for a new spoke type variable flux machine, with AlNiCo magnets, in the no-load condition. This method is based on the solution of a simple magnetic equivalent circuit of spoke type machines. The effect of stator slots on the air gap magnetic flux density is studied and uneven air gap length is modeled. Based on the no-load air gap magnetic flux density, the mean value of torque is calculated. The analytical and finite element design procedure of spoke type variable flux motor are reviewed briefly. Both analytical and finite element models are verified using test results of the prototyped motor and the effect of magnet length on the torque mean value is discussed, as well. P1110 Sensitivity of Manufacturing Tolerances on Cogging Torque in Interior Permanent Magnet Machines with Different Slot/Pole Number [#63]
The cogging torque is usually very sensitive to the manufacturing tolerances during machine mass production, and this paper investigates the different sensitivities between interior permanent magnet (IPM) machines with different slot/pole number combinations. Exemplified by two typical combinations, i.e. 12-slot/8 sl slot/8 sl slot/8 slot/8-pole and 12-slot/10-pole designs, the fundamental performance is firstly analyzed under ideal conditions. Then, with the tolerances of PM diversity and tooth-bulges considered, the most sensitive cases are identified for the two machines respectively, based on which the ultimate values of additional cogging torques are obtained and compared. In order to verify the different sensitivities, the field spatial harmonics in the two machines with and without considering the tolerances are further analyzed, from which the different origins of additional cogging torque components can be obtained respectively. Finally, the IPM prototypes with and without amplified tolerances are fabricated and tested to verify the analyses. P1111 Cogging Torque Minimization in Flux-Switching Permanent Magnet Machines by Tooth Chamfering [#278]
Due to the nature of doubly salient structure and high air-gap flux density, flux-switching permanent magnet (FSPM) machines typically suffer from large cogging torque, causing undesired acoustic noise and vibration, especially at low speeds. In this paper, various tooth chamfering methods for a 12/10 FSPM machine are proposed to reduce cogging torque. The influences of both circular bead and right angle as well as their possible combinations on cogging torque are investigated by 2D finite element analysis (FEA), and it turns out that employing right angles in both stator and rotor teeth is the most effective solution. Further, in order to explain this phenomena, the air-gap flux density is analyzed. Besides, the impacts on phase back electro-motive-force and electromagnetic torque are also evaluated. The predicted results indicate that the proposed technique can significantly reduce the peak value of cogging torque from 2.6Nm to 0.4Nm, while the reduction of average torque is only about 1.6%, which turns out to be an improvement when compared with the approach employed in previous literatures. P1112 Experimental research on the oil cooling of the end winding of the motor [#304]
for gaining an effective cooling performance for motor, water cooling is commonly utilized. But as the requirement for power density increasing, solely the water cooling is not sufficient. This is duo to the thermal resistance of the end winding to the water is large. To obtain lower temperature of the end winding, a new cooling method is studied. The stator and the rotor are separated by an ultrathin sleeve made of glass fiber, and the end winding is directly cooled by the oil in the space formed by the sleeve. Four different cooling schemes are evaluated through experiments. It is proved that the temperature of the end winding is reduced significantly, and the overall heat dissipation of the stator is improved. P1113 A Computationally Efficient Method for Calculation of Strand Eddy Current Losses in Electric Machines [#1293]
In this paper, a fast finite element (FE)-based method for the calculation of eddy current losses in the stator windings of randomly wound electric machines with a focus on fractional slot concentrated winding (FSCW) permanent magnet (PM) machines will be presented. The method is particularly suitable for implementation in large-scale design optimization algorithms where a qualitative characterization of such losses at higher speeds is most beneficial for identification of the design solutions which exhibit the lowest overall losses including the ac losses in the stator windings. Unlike the common practice of assuming a constant slot fill factor, sf , for all the design variations, the maximum sf in the developed method is determined based on the individual slot structure/dimensions and strand wire specifications. Furthermore, in lieu of detailed modeling of the conductor strands in the initial FE model, which significantly adds to the complexity of the problem, an alternative rectangular coil modeling subject to a subsequent flux mapping technique for determination of the impinging flux on each individual strand is pursued. The research focus of the paper is placed on development of a computationally efficient technique for the ac winding loss derivation applicable in design-optimization, where both the electromagnetic and thermal machine behavior are accounted for. The analysis is supplemented with an investigation on the influence of the electrical loading on ac winging loss effects for a particular machine design, a subject which has received less attention in the literature. Experimental ac loss measurements on a 12-slot 10-pole stator assembly will be discussed to verify the existing trends in the simulation results P1114 Core Loss Estimation in Electric Machines with Flux Controlled Core Loss Tester [#1516]
The complexity of core loss estimation is an essential limitation for electric machine design engineers. It is critical to estimate the core losses and reduce them in the design stage to improve the machine efficiency. Current estimation methods based on the Steinmetz equation and loss separation are not accurate enough even at the rated conditions. This work describes a loss estimation technique combining finite element analysis (FEA) and actual core loss measurements. First, flux waveforms from various parts of the electric machine are determined using finite element analysis (FEA), then identical flux density waveforms are generated in a toroidal wound core made out of the same material as is used in the machine. The loss is measured per unit mass, and then the total motor core loss is calculated by combining the measured W/kg loss values for predefined sections of the motor. Estimation results are provided and compared with the Bertotti iron loss and loss surface methods. The proposed method is shown to improve the accuracy of loss estimation. P1115 Thermal Analysis of a Three-Phase 24/16 Switched Reluctance Machine Used in HEVs [#1588]
This paper presents the thermal analysis of a 60 kW switched reluctance motor (SRM) under peak operating conditions for traction application in a hybrid electric vehicle (HEV). The SRM has 24 stator poles and 16 rotor poles, and three-phases. Heat generation losses are determined using finite element analysis (FEA) electromagnetic simulations and these losses are input into a lumped parameter thermal network (LPTN) simulation representing the thermal circuit of the electric machine. A range of coolant inlet temperatures are input and the testing of various priority operating speed points leads to the analysis of the rise in temperature of different components within the machine. By applying temperature limiting constraints of the copper windings and the rotor lamination surface, the operating times with varying coolant inlet temperatures and operating speeds can be determined. P1116 Pre-Drive Test of an Implemented Novel Radial-Gap Helical ROTLIN Machine [#307]
The future trend of mechanical systems is to substitute most of them by Permanent Magnet (PM) and/or Electromagnetic based ones. This paper presents an extension research on Design, Modeling, Simulation and Implementation Based Control of a novel ROTLIN (Rotary-Linear) Radial Gap Helical Machine. This is an hybrid of Magnetic Screw with a Synchronous Motor by modifying the design concept. The implemented machine is comprised of Stator, Mid-Layer Rotor and Inner Layer Translator, and tested as a high thrust force actuator. In the pre- drive tests, the back-EMF was measured and a relative rotational speed derived; Encoder signals and Position tracking were confirmed as well. The PD controller combined with DOB was designed but could not alleviate all vibrations in position response. The Pre-Drive Tests were conducted and Open Loop V/f control was used for preliminary experiments, consequently the Rotary and and relative Linear motions were confirmed.
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