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:
- Electromagnetic Interference (EMI) in Power Converters
- Modeling and Control of DC-AC converters I
- Induction Machines
- Prof. Subhasis Nandi Memorial Session: Diagnostics of Electric Machines
| 3:10PM Asymmetrical Duty-Cycle Control of Three-Phase Dual-Active Bridge Converter for Soft-Switching Range Extension [#1063]
Jingxin Hu, Nils Soltau and Rik W. De Doncker, RWTH Aachen University, Germany The three-phase dual-active bridge (DAB3) converter is a promising topology for high-power conversion in future dc grids due to bidirectional power flow, inherent soft-switching capability and reduced filter size. However, the conventional single phase-shift control (SPS) does not allow the soft- switching operation with large voltage variations in light load conditions. This paper proposes an asymmetrical duty-cycle control (ADCC) method for the DAB3 to extend the soft-switching range by realizing zero-current switching (ZCS). Three triangular and trapezoidal current modes are introduced, analyzed and seamlessly combined. It is established through loss analysis that the proposed modulation schemes reduce both the semiconductor and transformer losses substantially in light load conditions. By employing ADCC, the DAB3 can achieve high efficiency even under low load conditions. The proposed method has been validated by experimental results. 3:35PM Proposal of Dual Active Bridge Converter with Auxiliary Circuit for Multiple Pulse Width Modulation [#253]
A novel multiple pulse generation of DAB (dual active bridge) converter is proposed based on the auxiliary circuit for realization of complete soft-switching. The proposed auxiliary circuit enables multiple pulse width modulation (MPWM) with soft- switching. MPWM can transfer more power to the secondary side with the less peak inductor current when the output voltage ratio is very different from the transformer turn ratio, compared with the one pulse operation. It is verified through the experiments that DAB with the proposed auxiliary circuit was operated in the two-pulse soft-switching mode. Electromagnetic Interference (EMI) in Power Converters Monday, September 19, 1:30PM-4:00PM, Room: 102A, Chair: Shuo Wang, Sung Yeul Park 1:30PM A Simple Low-Cost Common Mode Active EMI Filter Using a push-pull Amplifier [#884] Dongil Shin, Changwoo Son, Seonho Jeon, Bongjin Cho, Jinwook Han and Jingook Kim, Ulsan National Institute of Science and Tech, Korea (South); Home Appliance Control Research Division LGE, Korea (South) A simple low-cost active EMI filter (AEF) without transformers is proposed. The equivalent circuit model of the proposed AEF is built, and a block diagram is extracted for efficient feedback analysis. The feedback loop gain and the performance of the AEF are calculated and validated by comparison with SPICE simulations. The proposed AEF enlarges the effective value of Y-capacitors. The AEF is manufactured for the application of a 2.2kW resonant inverter, and the performance is demonstrated by measurements of the conducted emissions. 1:55PM Two-capacitor Transformer Winding Capacitance Models for Common-Mode EMI Noise Analysis in Isolated DC-DC Converters [#1715]
For isolated DC-DC power converters, the inter-winding parasitic capacitance of the transformer is usually one of the main paths for common-mode (CM) noise. In order to simplify the CM noise analysis, this paper proposes a two-capacitor transformer winding capacitance model. The model is derived based on general conditions so it can be applied to different isolated converter topologies. A measurement technique is also proposed to obtain the lumped capacitance for the model. The CM noise models of several isolated converter topologies are analyzed with the proposed two-capacitor transformer winding capacitance model to achieve simplicity. Finally, the proposed transformer winding capacitance model and measurement technique are verified by simulations and experiments. 2:20PM Performance of Common-Mode-Voltage-Cancellation PWM Strategies with Consideration of Commutation Residues due to Double-Switching Waveforms [#985]
This paper focuses on pulse-width modulation (PWM) strategies that aim at cancelling common-mode (CM) voltage generated by power converters. In the typical use case of frequency converters, such strategies perform simultaneous switching between different inverter legs, so that their effects on CM voltage cancel each other. Doing so, the resulting CM voltage is reduced to mere commutation residues because simultaneous switching voltage waveforms may not be identical nor perfectly synchronous. Based on a PWM strategy that theoretically cancels the CM voltage generated by a variable-speed drive, this paper highlights the influence of desynchronization effects, commutation speeds, and different waveforms due to instantaneous currents, on the resulting CM voltage spectrum. Practical rules are derived in order to optimize the electromagnetic compatibility (EMC) performance of such PWM strategies. 2:45PM Identification of the Temporal Source of Frequency Domain Characteristics of SiC MOSFET Based Power Converter Waveforms [#762]
Certain Electromagnetic Interference (EMI) performance characteristics that occur in data taken from practical systems are often difficult to attribute to time domain features as waveforms will tend to deviate from the idealized analytical case. This paper shows that by taking multiple derivatives of experimental data and comparing this with the expected characteristics of a typical switching waveform it is possible to understand exactly which features of a given temporal waveform lead to certain spectral characteristics. It is also shown through analysis of analytical methods and experimental data that the smoother the transitions of a waveform the faster the roll off of the spectral content and hence the better the EMI performance. 3:10PM Resonance Phenomenon Influencing the Conducted-Mode Emission Test [#1048]
When measuring conducted-mode emission noise on power electronics equipment in order to check for compliance with the CISPR 14-1 emission standard, the measurement results often contain surprisingly high levels of conducted emission at frequencies between 10 MHz and 30 MHz. The high level of conducted emission is present even if the attenuation of the EMI filter in this frequency range should be more than adequate when checked. In the present paper it will be shown that the reason for exceeding the limits can be a resonant phenomenon involving the mains cable, the device under test and the shielded test chamber. This resonant problem cannot be solved by increasing the EMI filter attenuation. The paper explains how the resonance is excited, why increasing the filter attenuation cannot solve the problem and how the problem can be avoided. 3:35PM Modeling, Analysis and Design of Differential Mode Active EMI Filters with Feedforward and Feedback Configurations for AC-DC Converters [#1533]
This paper developed models for DM electromagnetic interference (EMI) input filters in AC-DC converters. The models are developed based on the circuit structures and control configurations. The models are developed for feedback, feedforward, feedforward-feedback and feedback-feedforward configurations. The closed loop gains are derived respectively. Based on the closed loop gain models, the open loop characteristics required for high performance active filters are determined. A passive filter topology which enhances the performance of the active filter is identified. The stability of active filters is analyzed and compared based on the developed models. The analysis is validated with both simulations and experiments. It is shown that the developed models can predict stability and help compensation design for active filters. Modeling and Control of DC-AC converters I Monday, September 19, 1:30PM-4:00PM, Room: 202D, Chair: Wim van der Merwe, Yi Deng 1:30PM Compensation for Inverter Nonlinearity Considering Voltage Drops and Switching Delays of Each Leg's Switches [#1499] Myeong-Chan Kang, Sang-Hoon Lee and Young-Doo Yoon, Myongji University, Korea (South) This paper proposes a compensation method for inverter nonlinearity for an accurate voltage synthesis. The inverter nonlinearity is caused by dead-times, voltage drops and switching delays and parasitic output capacitance of semiconductor switches, and propagation delays in the gate drive circuits. This paper regards dead-times, voltage drops and switching delays of semiconductor switches as dominant voltage distortion factors. Analyzing those factors of each leg, the proposed method compensates nonlinearity of each leg of inverters. As a result, accurate voltages can be synthesized. Experimental results verify the effectiveness of the proposed method. 1:55PM Small-signal Terminal-Characteristics Modeling of Three-Phase Droop-Controlled Inverters [#1628]
Droop-controlled inverters are widely employed as power sources in three-phase AC power electronics system, such as distributed generation, while the interaction between the source and the load may lead overall system to be unstable. Terminal-characteristics based stability criteria are very attractive for analyzing the stability of three-phase AC power electronics system. However, the systems, composed by droop-controlled inverters, exhibit the dynamical variation of fundamental angular frequency, and existing stability analysis approaches are just suitable for systems with constant fundamental angular frequency. To overcome this problem, this paper proposes small-signal terminal-characteristics model of the three-phase droop-controlled inverter covering the dynamic of fundamental angular frequency, and both current mode operation and voltage mode operation are taken into account. Finally, the proposed model is verified in frequency domain. 2:20PM Enhancement of Current and Voltage Controllers Performance by Means of Lead Compensation and Anti-Windup for Islanded Microgrids [#766]
The decoupling of the capacitor voltage and inductor current has been shown to improve significantly the dynamics performance of voltage source inverters in isolated microgrids. However, still the computation and PWM delays limit the achievable bandwidth. A technique based on a lead compensator structure is proposed to overcome this limitation. It is shown how a widen bandwidth for the current loop with still well damped characteristics allows to enlarge the outer voltage loop bandwidth. These features are demanding requirements in high performance islanded applications. Discrete-time domain implementation issues of an anti-wind up scheme are discussed as well. In fact, algebraic loops can arise if the wrong discretization method is used making unfeasible the real-time implementation of digital controllers. Experimental tests in accordance with the standards for UPS systems verify the theoretical analysis. 2:45PM DC-Link Current Ripple Component RMS Value Estimation Considering Anti-Parallel Diode Reverse Recovery in Voltage Source Inverters [#144]
To estimate the RMS value of the DC-link ripple current more accurately, a method is developed considering the reverse recovery of the anti-parallel diode in voltage source inverters (VSIs). In this paper, using the analysis of the inverter DC-link current and anti-parallel diode reverse recovery, calculations are implemented based on the SPWM technique. According to the calculations and simulation and experimental results, it is shown that the calculated ripple current RMS values are higher and closer to the actual values when the diode reverse recovery is considered. In addition, inverter switching frequency also influences this value. Comparing with the experimental results, the error of the DC-link ripple current RMS value estimated by the proposed method vary under different inverter operating conditions and are between 0.1% and 10.5%. 3:10PM Digital Dead-Beat and Repetitive Combined Control for Stand-Alone Four-Leg VSI [#727]
This paper deals with a newly conceived combine control topology. Dead-Beat and Repetitive controllers are proposed to operate jointly in 4-leg VSI for stand-alone applications. In such mode of operation, dedicated controller has to regulate the inverter output voltages, which are measured at the output of the power filter. Each control topology exhibits some specific features. Dead-Beat can rapidly compensate output voltage variations due to load changes; on the contrary, Repetitive Control can provide the required harmonic compensation capabilities that are mandatory to comply with the Standards, when balanced and unbalanced non-linear loads have to be fed. 3:35PM Modeling, Analysis, and Impedance Design of Battery Energy Stored Single-Phase Quasi-Z-Source Photovotaic Inverter System [#1080]
The battery energy stored quasi-Z-source (BES-qZS) based photovoltaic (PV) power generation system combines advantages of the qZS inverter and the battery energy storage system. However, the second harmonic (2W) power ripple will degrade the system's performance and affect the system's design. An accurate model to analyze the 2W ripple is very important. The existing models did not consider the battery, and with the assumption L1=L2 and C1=C2, which causes the non-optimized design for the impedance parameters of qZS network. This paper proposes a comprehensive model for single-phase BES-qZS-PV inverter system, where the battery is considered and without any restriction of L1, L2, C1, and C2. A BES- qZS impedance design method based on the built model is proposed to mitigate the 2W ripple. Simulation and experimental results verify the proposed 2W ripple model and design method. Induction Machines Monday, September 19, 1:30PM-4:00PM, Room: 101A, Chair: Andy Knight, Andrea Cavagnino 1:30PM High Torque Density Induction Motor with Integrated Magnetic Gear [#849] Dalia Abdelhamid and Andrew Knight, University of Calgary, Canada This paper presents a design process to integrate a magnetic gear with an induction machines. The resulting integrated machine has the potential to offer a high torque density with asynchronous speed characteristics. Such characteristics may be desirable for applications that require sensorless operation or may be subject to severe backlash or jamming. The paper presents some of the difficulties in the design process as compared to the design process for PM machines. A prototype design at small scale is developed, and simulation results demonstrate the potential for high torque density low-speed high-torque induction motor. 1:55PM Accurate Determination of Induction Machine Torque and Current versus Speed Characteristics [#776]
The determination of induction machine torque and current speed characteristics relies on methods based on either direct testing or calculation, using machine equivalent circuit. Both methods may lead to significant errors. The paper discusses the challenges encountered using these methods and an approach is presented in the paper to overcome the inherent challenges. The proposed approach considers saturation and compensates for skin effect and machine temperature to improve accuracy. Five induction motors of different pole pairs were analyzed and tested to provide understanding of the underlying issues of predicting torque and current characteristics of induction machines. The findings indicate that, for direct testing, multiple data points closer to nominal voltage are required. In the case of equivalent circuit modeling, proper correction of the model for temperature and saturation leads to improved prediction of the torque characteristics of general purpose induction machines. 2:20PM The Novel SLIM Method for the Determination of the Iron Core Saturation Level in Induction Motors [#1556]
Lately, a new diagnostic mean has been introduced for reliable fault diagnosis in delta-connected induction motors. This diagnostic mean is the zero-sequence current frequency spectrum. It will be shown in this paper that, the zero- sequence current waveform can be reliably used for identifying the induction motor's iron core saturation level. So in this work, simulations with the Finite Element Method and experimental testing are carried out, with the healthy induction motor operating under different load levels. The paper proposes a novel method called SLIM for reliable induction motor saturation level determination. 2:45PM Rotor Design to Reduce Secondary Winding Harmonic Loss for Induction Motor in Hybrid Electric Vehicle Application [#438]
Induction motor rotor designs are investigated in this paper to reduce secondary winding harmonic losses in hybrid electric vehicle (HEV) application. The induction motor is more and more popular to use for the traction drive, but its' secondary winding harmonic losses are significantly higher than the usual when having high frequency and high power density in the HEV application. Thus, the major cause of the high secondary winding losses is analyzed and evaluated in the paper. The losses of rotor bars due to harmonic field are calculated and analyzed for a typical eight pole induction motor by using the finite element method (FEM). Several rotor structures are proposed to decrease the harmonic losses and improve efficiency. Finally, the rotor design methods of the induction motor are compared to achieve a high efficiency and high power density based on the reduced harmonic losses, increased efficiency and output torque. The results show the secondary winding losses of the induction motor can be reduced by up to 43% when using the new rotor structure design. 3:10PM A Novel In Situ Efficiency Estimation Algorithm for Three-Phase Induction Motors Operating with Distorted Unbalanced Voltages [#9]
This paper presents a novel algorithm for in situ efficiency estimation for induction motors operating with distorted unbalanced voltages. The proposed technique utilizes the genetic algorithm, IEEE Form F2-Method F1 calculations, large motor test database and a new stray-load loss formula. The technique is evaluated by testing 3 small- and medium-sized induction motors with 11 different combinations of voltage unbalance and total harmonic distortion. The results showed acceptable accuracy. The technique may be used as a potential industrial tool that can help derate induction motors in the presence of voltage unbalance and harmonics distortion. 3:35PM Development and Efficiency estimation of a Regenerative Test Rig for Induction Motor Testing [#670]
This paper presents the development and error analysis of a flexible test rig which is intended for emulating the static and dynamic characteristics of some mechanical loads found in industry. The test rig will provide a laboratory- based platform for assessing the efficiency of inverter-fed induction motors (IM) within a wide range as well that of variable speed drives (VSDs). The use of an Active Front End (AFE) with regenerative capabilities allows the power generated by the motor drive to be recycled within the system. An in-depth error analysis is conducted on the complete system. This is done by analyzing raw data obtained by means of 2 commercial instruments. Detailed comparisons of the error bands were done for the results obtained. Prof. Subhasis Nandi Memorial Session: Diagnostics of Electric Machines Monday, September 19, 1:30PM-4:00PM, Room: 102B, Chair: Hamid Toliyat, Sang Bin Lee 1:30PM A Voltage Based Approach for Fault Detection and Separation in Permanent Magnet Synchronous Machines [#248] Reemon Haddad, Cristian A. Lopez, Shanelle Foster and Elias Strangas, Michigan State University, United States Different faults in Permanent Magnet Synchronous Machines will cause various and independent changes to the machine magnetic flux distribution, which will cause different changes to the machine parameters and performance. These changes will be reflected in the machine flux linkages, which can be determined from the machine voltages. In this paper, a method is proposed to detect and separate three types of faults in Permanent Magnet Synchronous Machines: static eccentricity, demagnetization, and turn-to-turn short circuit. The proposed method is based on using the direction of the shift in the commanded d and q axis voltages while the machine is operating at steady state. Simulation tests using Finite Element Analysis software (MAGSOFT- Flux2D) were performed under healthy and faulted conditions on a 3 phase 10- pole fractional slot concentrated winding Permanent Magnet Synchronous Machine. Experimental tests were carried out and compared with Finite Element Analysis for the same machine under demagnetization and turn-to-turn short circuit faults. The effects of the speed and temperature variations were simulated to validate the detection method under different operating conditions. 1:55PM Permanent Magnet Generator Turn Fault detection Using Kalman Filter Technique [#1081]
In this paper, a stator turn fault detection strategy is developed for a permanent magnet (PM) generator system. Unlike conventional power generation systems, the output of the PM generator is directly rectified by an uncontrolled diode bridge. The only accessible signal is the DC link current/voltage. As a result, most existing detection techniques based on the phase current/voltage signals are not applicable. Instead, the 2nd and 6th harmonics of the DC link current are exploited for turn fault detection and they are extracted by a Kalman filter. It is shown that the phase unbalance caused by a turn fault gives rise to significant increase in the 2nd harmonic DC link current. Consequently, the dominant harmonic under healthy and fault conditions are of the 6th and 2nd orders, respectively. Hence, the turn fault can be detected by comparing the magnitudes of the two harmonics. The detection method is assessed by extensive simulation under various fault scenarios. It is shown that the developed Kalman filter method exhibits significant advantages in response time and computation effort than online fast Fourier transform (FFT) based techniques.
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