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: Electric Drives
| P2902 Six-Leg Dc-Link Rectifier/Inverter for Two-Phase Machines [#1082]
Nayara Brandao de Freitas, Cursino Brandao Jacobina and Alexandre Cunha Oliveira, Federal University of Campina Grande, Brazil This paper proposes two different configurations of two-phase induction motor drives. These topologies utilize a single-phase supply to feed a two-phase machine/load and are more suitable when the amplitude of the load voltage is half the amplitude of the grid voltage. One of the topologies is transformerless and the other is transformer-based. The drive systems provide power factor control and DC-link voltage control. Pulsewidth modulation techniques for the converter control are discussed. Simulation and experimental results are provided to illustrate and compare the operation of the systems. P2903 RSM-DE-ANN Method for Sensitivity Analysis of Active Material Cost in PM Motors [#1275]
In this paper, a numerical technique is developed for sensitivity analysis of active material cost (AMC) in PM motors with distributed and fractional slot concentrated windings. A comprehensive analysis is carried out to identify how the optimal design rules and proportions of IPM motors with sintered NdFeB magnets vary with respect to the changes in the commodity prices of permanent magnet material, copper, and steel. The sensitivities of the correlations between the design parameters and the AMC with respect to the commodity price ranges are investigated based on response surface methodology (RSM) and large-scale design optimization practice using differential evolution (DE) optimizer. An innovative application of artificial neural network (ANN)-based design optimization is introduced. Multi-objective minimization of cost and losses is pursued for an overall of 200,000 design candidates in 30 different optimization instances subjected to different cost scenarios according to a systematic design of experiments (DOE) procedure. An interesting finding is that, despite common expectations, the average mass of steel in the optimized designs is more sensitive to changes in the commodity prices than the masses of copper and rotor PMs. P2904 Modeling, simulation and performance evaluation of caged permanent magnet motors fed by variable speed drives (VSDs) [#507]
With increasing demand for higher efficiency, engineers are looking for an alternative solution to replace induction motors (IMs) in many applications. One of the very promising topologies is the permanent magnet (PM) motor with a squirrel cage on the rotor, which is referred to as the cage rotor PM motor in this paper. Based on the literature survey, the cage rotor PM motors have been studied and compared to IMs for direct on-line applications. Some studies also investigated the performance of line start PM motors (LSPMs) using a conventional VSD by comparing it to an IM using the same VSD. The comparative evaluation shows that, in most operating conditions, the LSPM drive provides better performance (usually higher efficiency) than the IM drive. In this paper, a d-q dynamic analytical model of the cage rotor PM motor is derived. The model is intended to be used in place of finite element analysis (FEA) and for purposes of control development. The model is implemented in Matlab/Simulink and used to study the behavior of different types of the cage rotor PM motor; line-start PM and light cage PM motors, when fed by a standard, scalar controlled drive. The analytical results are verified against the FEA, which shows excellent agreement. P2905 An Improved Conformal Mapping Aided Field Reconstruction Method for Modeling of Interior Permanent Magnet Synchronous Machines [#611]
An improved field reconstruction method (IFRM) to model interior permanent magnet synchronous machine (IPMSM) is proposed to reduce computation time. In modeling IPMSM with conventional FRM, in order to include slotting effect, the basis function at various rotor positions has to be obtained and stored which increases the workload. The saturation and slotting effect can be avoided by employing conformal mapping (CM) method which maps the slotted stator into a slotless structure. As a result, only one set of basis functions at one rotor position would be necessary. The slotting effect is modeled as equivalent permeability which includes the information of rotor position. Hence, the field density distribution in the slotted structure is the product of the flux density distribution of slotless structure and the equivalent permeability. FEA simulation is conducted to evaluate the results from improved FRM and to validate the effectiveness of the IFRM. P2906 Hybrid Excited Vernier PM Machines with Novel DC-Biased Sinusoidal Armature Current [#730]
In this paper, a novel class of hybrid excitation, stator vernier permanent magnet (VPM) machines (HE-VPM) are proposed. The proposed machines are with salient rotor structure, stator located PMs, and concentrated armature windings. Therefore, the superiority of the proposed machine is robust rotor structure, short and non- overlapping end-winding, and easy heat dissipation. Besides, a novel DC-biased sinusoidal current, which contains an alternating current (AC) component and a direct current (DC) component, is applied, with this novel current, a novel hybrid excited VPM machines without additional field windings are obtained. The simulation results shows that the proposed machines exhibit higher torque density, power factor, and efficiency, Also, the constant power operation range is broadened, as the injected DC biased current can weaken or enhance the exciting fields at high/low speed. Finally, a prototype has been designed and under built, and the corresponding experiments will be added later. P2907 Calculating the Electromagnetic Field and Losses in the End Region of Large Synchronous Generators under Different Operating Conditions with Three-Dimensional Transient Finite Element Analysis [#851]
The significant losses in the end components due to the leakage magnetic field excited by the armature and field end windings can result in partial overheating and is an important consideration in the design of large synchronous generators. This paper describes an approach based on the three-dimensional (3D) transient finite element analysis (FEA) to determine the fields and losses in the generator end region. Taking the nonlinear anisotropic properties of the stator core, as well as the slitting and stepping shape of core-end packets into consideration, the electromagnetic field and loss distribution in the end region is calculated. The method is validated by the agreement found between the temperatures predicted by the 3D stationary thermal FEA and the temperatures obtained from a physical measurement at various points in the generator. Then, the field and loss distributions in the end region under the open- circuit test condition, power factor lagging condition and leading condition are analyzed and compared using the proposed transient 3D FEA method. P2908 Electrical Propulsion System Design of Chevrolet Bolt Battery Electric Vehicle [#1210]
A permanent magnet synchronous motor (PMSM) motor is used to design the propulsion system of GMs Chevrolet Bolt battery electric vehicle (BEV). Magnets are buried inside the rotor in two layer V arrangement. The Chevrolet Bolt BEV electric machine rotor design optimizes the magnet placement between the adjacent poles asymmetrically to lower torque ripple and radial force. Similar to Chevrolet Spark BEV electric motor, a pair of small slots are stamped in each rotor pole near the rotor outer surface to lower torque ripple and radial force. Rotor design optimizes the placement of these slots at different locations in adjacent poles providing further reduction in torque ripple and radial force. P2909 Optimizing PM Coverage Ratio in Flux Concentrating Axial Flux Machine [#1583]
A two-stator, one-rotor axial motor is considered for bike applications. It has a 24 slot 20 pole structure, and concentrated pole windings. Two stator cores are made with the laminated sheets instead of the soft magnetic composite (SMC). PMs are magnetized to the circumferential direction for concentrating the PM flux. The air-gap field is analyzed based on a simplified 2D model, and is solved for optimal permanent magnet (PM) ratio. The optimum PM coverage ratio is determined based on 3D FEM results. A prototype motor was built, and back EMF was tested. P2910 Detailed Analytical Modelling of Fractional-Slot Concentrated-Wound Interior Permanent Magnet Machines for Prediction of Torque Ripple [#193]
The standard dq model of interior permanent magnet machines is based on the assumption of sinusoidal machine parameters. This assumption is flawed especially when a fractional-slot concentrated-wound stator is utilized. In order to address this deficiency, in this paper the non-sinusoidal machine parameters are modelled in the abc-system. An extended dq-model is then proposed based on the derived non-sinusoidal machine parameters. New parameters are introduced in the proposed model and experimental tests are described for their determination. Based on the proposed extended dq-model, detailed equations for the average torque and torque ripple are proposed that specify the parameters involved in the production of different torque components. The proposed extended dq-model is used to predict the performance of a prototype fractional-slot concentrated-wound interior permanent magnet machine. P2911 A compact and light-weight generator for backpack energy harvesting [#1138]
The reciprocating linear motion of a heavy backpack during walking has proved to be a viable source from which significant amount of electricity can be harvested. The energy harvesting systems proposed so far either use a mechanical rack and pinion to convert the linear motion to rotation or use a direct drive permanent magnet linear generator. This paper makes the case for the use of a magnetic gear to convert the linear motion to rotation. Compared to the mechanical rack and pinion, the proposed system is expected to have less noise, friction, and maintenance requirement and to facilitate the packaging. Compared to a direct drive linear generator, the proposed system would be multiple times lighter and compacter. The principles of backpack energy harvesting are outlined and design specifications of the proposed system are derived. An initial design is presented along with some simulation results. P2912 Suspension Loss Measurement and its Reduction in Single-Drive Bearingless Motor [#1380]
This paper presents a new estimation method of magnetic suspension loss in one degree- of-freedom (1DOF) actively positioned single-drive bearingless motors. In the 1DOF bearingless motors, only axial z-axis direction is actively positioned. The other axes, radial movements and tilting movements, are passively stabilized. Single-drive bearingless motors can generate both torque and active axial force in q- and d-axis currents, respectively, by only one three-phase inverter. In this paper, the magnetic suspension loss is estimated in experimental results. In addition, it is confirmed that the magnetic suspension loss is decreased with an adaptation of a zero power control. P2913 A Compact Single-Phase Adjustable-Voltage-Ratio Magnetoelectric Transformer [#1683]
Adjustable-voltage-ratio (AVR) magnetoelectric transformer is a new type of power transformer whose voltage ratio between the output and input can be adjusted continuously from the minimum value (e.g., zero) to the maximum value designed. Therefore, given an input voltage with fixed amplitude, the AVR transformer can output one or multiple AC voltages with continuously adjustable amplitudes from zero volts to the maximum value. In this paper, a new structure- compact single-phase AVR transformer is proposed. The configuration and working principle of the proposed AVR transformer are presented. Finite element analysis (FEA)-based simulation analysis and preliminary experimental results are provided to demonstrate the proposed novel transformer concept. P2914 Analysis of Common Mode Circuit of BDFG-Based Ship Shaft Power Generation System [#843]
In brushless doubly-fed generator (BDFG)-based ship shaft power generation system, the two back-to-back converters bring two common mode voltage sources and BDFG's two sets of stator wingdings provide several common mode current branches, which make the common mode circuit complicated. This paper have listed the common mode current loops and proposed an equivalent common mode circuit model based on lumped parameters for the system. The common mode impedances of the system have been acquired by measuring and calculating. The common mode current loop consists of two sets of stator wingdings and two back-to-back converters has been discussed with emphases. Simulation and experimental results agree with each other well and they verify the validity of the proposed model and the analysis about common mode circuit. P2915 Replacing SPM by PMARel machines in low-speed high-torque applications [#580]
The aim of this paper is to evaluate alternatives to Surface-mounted Permanent Magnet (SPM) machines in low-speed high-torque applications, such as elevator systems, grindstones and positioning systems, where the electrical motor is directly connected to the load. In particular, the potentiality of PM-Assisted Reluctance (PMAREL) machines is deeply investigated. The capability of an SPM motor (adopting either NdFeB or Ferrite magnets) is compared with those of PMAREL motors employing Ferrite magnets. Different solutions are considered, varying the number of slots and poles, taking into account both distributed and fractional-slot winding. The analysis highlights the satisfactory performance of the PMAREL motors with distributed winding. On the contrary, the configurations with fractional-slot winding exhibit worse torque quality, even though different results are found according to the machine periodicity. P2916 Rotor Eddy-Current Loss Minimization in High-Speed PMSMs [#839]
In high-speed permanent-magnet synchronous machines (PMSMs), the permanent magnets (PMs) are usually retained by high strength sleeves. Metallic sleeves are preferred in some cases where a high rotor stiffness is required. However, high frequency time and spatial harmonics of the air-gap field would induce considerable eddy-current losses in the conductive sleeve, and thus exposing the PMs to risk of overheating and demagnetization. In this paper an 80 kW, 80,000 rpm PMSM is designed for air blowers. The initial design and analysis show that the rotor is overheated due to the high rotor losses when a titanium sleeve is used. Some existing methods for rotor loss reduction, namely copper shield and grooving the sleeve, are investigated for the design. Furthermore, a hybrid sleeve, which contains an inner titanium cylinder and an outer cylinder made of carbon fiber composite (CFC), is also proposed for this machine. The performances of various sleeves are studied in detail, considering the rotor eddy-current losses, the mechanical stress, and the temperature rise. The conclusions may provide some references for the design of high-speed PMSMs. P2917 Design and Analysis of Rotating Diode Rectifier for Wound-Rotor Synchronous Starter/Generator [#1328]
The structure of rotating diode rectifier were proposed in this paper to solve the excitation problem of brushless wound-rotor synchronous starter/generator. Rotating diode rectifier plays an important part of excitation system of main generator. Triple Rectifier was adopted to take the place of three-phase rectifier. The three phase armature windings connect to a full-bridge rectifier each other. Every full-bridge rectifier connects together in a series to provide field current for the Main Generator. Compared with three-phase rectifier, this new Rectifier can take advantage of all phase winding voltage at any moment, then the exaction fielding winding current of Main Generator will be increased. An experimental platform was built and experimental results verified the feasibility and advantages of the triple rectifier. P2918 Stator Tooth and Rotor Pole Shaping for Low Pole Flux Switching Permanent Magnet Machines to Reduce Even Order Harmonics in Flux linkage [#1407]
High-speed machines require structurally robust rotor to withstand high centrifugal forces. Flux switching permanent magnet (FSPM) machines are ideal for high speeds since they have a simple and robust rotor structure. They also utilize permanent magnet (PM) in the stator enabling them to achieve high power density. It is desirable to keep the operating frequency minimized to reduce core losses and cost of power electronics. A 6-stator slot, 4-rotor pole (6/4) FSPM machine has the lowest operating frequency for a three phase FSPM configuration but suffers from heavy harmonic distortion in flux linkage. This paper aims to identify structural modifications that can minimize the dominant 2nd order harmonic component to make the 6/4 configuration amiable for high-speed applications. The analysis and methods proposed in this paper will be useful P2919 Optimization of PM Volume in a PM-assisted Claw-Pole Motor for ISG Applications [#1559]
Claw-pole motor has naturally 3D structure, because of the structural complexity. However, it was simplified as a 2D model by linear approximation. The rotor model of PMassisted claw-pole motor has permanent magnets, as well as a field winding. Then an electric equivalent circuit is developed with a current source and a voltage source. Further, the rotor core saturation problem is treated with a nonlinear resistance (reluctance) which depends on the field current. The resistances are obtained from 3D FEM results, and used for computing an optimal PM volume. A real machine was constructed based on the computation results, and tested in a dynamo with an inverter. Poster Session: Electric Drives Tuesday, September 20, 11:00AM-12:30PM, Room: Exhibit Hall, Chair: Uday Deshpande, Gianmario Pellegrino P3101 Improved Model Predictive Current Control of Permanent Magnet Synchronous Machines with Fuzzy Based Duty Cycle Control [#1239] Amir Masoud Bozorgi, Mehdi Farasat and Seyyedmahdi Jafarishiadeh, Louisiana State University, United States Model predictive current control uses a model of the machine and an appropriate cost function to indirectly control electromagnetic torque and reactive power. However, due to sensitivity of model predictive control (MPC) to system parameters, need for high sampling frequency, and high torque and flux ripples, this method is not employed in a wide variety of commercial drives. Incorporating the concept of duty cycle and applying two voltage vectors during a sampling period can reduce the torque and stator current ripples of a model predicative current controlled synchronous machine. In this paper, duty cycles of the voltage vectors are determined effectively using a fuzzy logic modulator. In addition, a full order Luenberger observer is designed for accurate estimation of motor variables in presence of parameter uncertainties. Matlab and real-time simulation results confirm the effectiveness of the proposed MPC. P3102 A Universal Restart Strategy for Induction Machines [#245]
This paper presents an approach to implement the universal flying restart for an induction machine using a frequency search algorithm that determines the rotor speed so that the correct frequency and voltage can be applied to minimize the inrush current during the restart. This method only uses the measured phase current and the motor nameplate parameters, thus making it ideal for use with scalar-controlled motor drives. An additional benefit of the proposed approach is that the time to estimate the rotor speed is independent of the motor parameters, and is defined by the restart algorithm itself. Beyond the development of the algorithm, implementation issues will be considered to provide general guideline for the application of the developed algorithm. P3103 Active Disturbance Rejection Control of Linear Induction Motor [#348]
This paper proposes the theoretical framework and the experimental application of the active disturbance rejection control to linear induction motors. Such a non-linear control technique can be viewed as a particular kind of input-output linearization control technique, where the non-linear transformation of the state is not a priori given by a model, while it is estimated on-line. Such an approach permits to cope with modelling errors as well as any uncertainty in the knowledge of the model parameters. The effectiveness of the proposed active disturbance rejection control law has been verified experimentally on a suitably developed test set-up. P3104 Super-Twisting Algorithm Based Sliding-Mode Observer with Online Parameter Estimation for Sensorless Control of Permanent Magnet Synchronous Machine [#276]
Online parameter estimation could improve the performance of sensorless control. In this paper, a super-twisting algorithm (STA) based second-order sliding-mode observer (SMO) sensorless con-trol with online stator resistance estimation is proposed. The chattering problem and time delay, which could not be avoided in conventional SMO, are eliminated in this STA based second-order SMO. At the same time, a parallel online stator resistance estimation algorithm is proposed based on a first-order SMO. With the help of the online stator resistance estimator, the per-formance of the sensorless control is improved in terms of system stability and position accuracy. The stability of the online stator resistance estimator is proved by Lyapunov function. Finally, the STA based sensorless control method with online stator re-sistance estimation is verified and compared with conventional methods by simulation and experiments.
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