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:
- Batteries and Battery Management for Transportation Electrification II
- Multi-Phase Inverter
- AC-AC Converters I
- Modular Multilevel Converters (MMC) II
- DC-DC Isolated: Resonant
| 11:45AM Distributed Voltage Control and Load Sharing for Inverter-Interfaced Microdrid with Resistive Lines [#804]
Mohammad S. Golsorkhi, Qobad Shafiee, Dylan D.C. Lu and Josep M. Guerrero, School of Electrical and Information Engineering, Australia; Department of Electrical and Computer Engineerin, Iran; The Institute of Energy Technology, Aalborg Univ, Denmark This paper proposes a new distributed control method for coordination of distributed energy resources (DERs) in low-voltage resistive microgrids. The proposed framework consists of two level structure; primary and secondary control. Unlike the existing distributed control methods, the proposed method is based upon the practical assumption of resistive network impedance. In this context, a V-I droop mechanism is adopted in the primary control level, where GPS timing is used to synchronize the control agents. A new distributed secondary control method based on consensus protocol is introduced to improve the voltage regulation and load sharing accuracy of the V-I droop method. In this method, the d-axis components of the voltage is altered so as to regulate the average microgrid voltage to the rated value while guarantying proper sharing of active power among the DERs. Additionally, the q-axis component of voltage is adjusted to perform proper current and, accordingly reactive power sharing. The proposed control methodology accounts for the distribution line impedances. It features a plug-and-play environment; prior system knowledge is not required, and an arbitrary DER can enter the microgrid without any need for additional synchronization mechanisms. An AC microgrid is prototyped to experimentally demonstrate the efficacy of the proposed method. Batteries and Battery Management for Transportation Electrification II Thursday, September 22, 10:30AM-12:10PM, Room: 102D, Chair: Oliver Gross, Omer Onar 10:30AM Accurate Battery Parameter Estimation with Improved Continuous Time System Identification Methods [#699] Bing Xia, Xin Zhao, Raymond de Callafon, Hugues Garnier, Truong Nguyen and Chris Mi, San Diego State University, United States; University of California San Diego, United States; University of Lorraine, France The modeling of Lithium-ion batteries usually utilizes discrete-time system identification methods to estimate parameters of discrete models. However, in real applications, there is a fundamental limitation of the discrete-time methods in dealing with sensitivity when the system is stiff and the storage resolutions are limited. To overcome this problem, this paper adopts direct continuous-time system identification methods to estimate the parameters of equivalent circuit models for Lithium-ion batteries. Compared with discrete- time system identification methods, the continuous-time system identification methods provide more accurate estimates to both fast and slow dynamics in battery systems and are less sensitive to disturbances. A case of a second order equivalent circuit model is studied which shows that the continuous-time estimates are more robust to high sampling rates, measurement noises and rounding errors. In addition, the estimation by the conventional continuous-time least squares method is further improved in the case of noisy output measurement by introducing the instrumental variable method. Simulation and experiment results validate the analysis and demonstrate the advantages of the continuous-time system identification methods in battery applications. 10:55AM A Real World Technology Testbed for Electric Vehicle Smart Charging Systems and PEV-EVSE Interoperability Evaluation [#1461]
Global sales of electric vehicles passed the 1 million unit mark in 2015. These grid-sourced electric vehicles operators require reliable access to seamless delivery of electricity to their vehicles for dependable transportation. Electrical utilities and other electrical distribution infrastructure owner/operators require the electrical vehicles using their services to be non- disruptive with reasonable return on investment revenues. Standards Defining Organization (SDO) committees are composed of subject matter experts that formalize requirements for the respective standards topic, based on needs of the stakeholders. Validation of standards, component-system compliance to standards, and interoperability of systems between standards requires testing. This testing can be simulation or model based as well as component and system level evaluation. This paper describes requirements and challenges to build a real-world testbed for EV-smartgrid interoperability assessment. AC, DC, and Wireless charging methods are addressed as well of balance of system topic such as grid impacts, metrology, dispatch of resources, and vehicle-infrastructure communication. 11:20AM Modeling of Low-Temperature Operation of a Hybrid Energy Storage System with a Butler-Volmer Equation Based Battery Model [#1472]
Lithium-ion battery performance is significantly reduced at low temperatures, where substantially increased resistance reduces power capability and lithium plating causes charging limitations. To reduce the low-temperature limitations of an electric vehicle battery pack, a hybrid energy storage system consisting of a battery pack, an ultracapacitor pack, and a dc/dc converter is investigated. A low-temperature battery model that includes a nonlinear resistance based on the Butler-Volmer equation and an ultracapacitor model are developed, and the model parameters are experimentally measured for temperatures from -20 to 25 degrees Celsius. The models are then appropriately scaled for a full-size electric vehicle and paired with a dc/dc converter loss model. The optimal power split is determined for various drive cycles using a dynamic programming optimization algorithm. It is shown, using both analytical and experimental results, that the hybrid energy storage system is an excellent approach for substantially reducing the total energy storage system losses at low temperatures, as well as increasing regenerative braking energy capture, reducing output power limiting, and increasing vehicle range. 11:45AM Voltage and Current Signals De-noising with Wavelet Transform Matrix for Improved SOC Estimation of Lithium-ion Battery [#958]
The electromagnetic environment of the lithium-ion battery in the Electric Vehicles (EVs) is severe. Moreover, the load current of the battery in the EVs changes drastically and randomly depending on the EV driving condition. As a result, the voltage and current signals measured by the Battery Management System (BMS) normally contain the noise such as the white noise. This results in the estimation error of the State of Charge (SOC). A new voltage and current de-noising approach based on Wavelet Transform Matrix (WTM) is proposed in this paper to improve the accuracy of the SOC estimation using Extended Kalman Filter (EKF) algorithm. This approach reduces the computation complexity and the measuring noise is de-noised effectively. It was validated by the experimental results on a 1665132 model laminated Li(NiCoMn)O2 battery with the rated capacity of 200 Ah and rated voltage of 3.6 V. The voltage of the battery ranges from 3.2 V to 4.2 V. The accuracy of the SOC estimation is improved significantly and the error is limited within 1.5% less than the error of 6% by EKF without de-noising. Multi-Phase Inverter Thursday, September 22, 10:30AM-12:10PM, Room: 202A, Chair: Babak Parkhideh, Raja Ayyanar 10:30AM Improved r-Z-Source Inverter [#354] Zeeshan Aleem and Moin Hanif, University of Cape town, South Africa; University of Cape Town, South Africa This paper proposes a new improved gamma Z-source inverter (rZSI) that overcomes the drawbacks faced by the conventional rZSI. The improved rZSI provides continuous input current and higher voltage gain compared to the conventional inverter. Moreover, an extra diode provides a path for the energy in the leakage inductance to flow to the load in a non oscillatory manner and reduces the voltage spikes across the switches. The improved rZSI compared to the conventional rZSI can use a higher modulation index and consequently a lower shoot through duty for the same input voltage, output voltage and transformer turn ratio, thus, having lower stress across the inverter bridge. It has an improved power factor and better output waveform quality. To validate the advantages of the proposed inverter, analytical, simulated and experimental results are presented. 10:55AM High-Frequency Six Pulse DC Link Based Bidirectional Three-Phase Inverter without Intermediate Decoupling Capacitor [#1577]
Cascaded bidirectional dc-ac converters are commonly used in UPS application and battery chargers for electric vehicles (EV). A bidirectional dual active bridge cascaded three phase converter (DABCC) with six pulse dc link, high reliability and low cost is proposed for applications like line interactive UPS and EV. Power conversion units for such applications use large electrolytic capacitor at high voltage DC bus. Through a novel modulation technique Six Pulse Modulation (SPM), this electrolytic capacitor is eliminated that results in increased reliability, compactness and reduced cost. It needs only single H-bridge and one single-phase transformer at front-end for the required three-phase conversion. SPM technique also increases DC bus utilization and decreases the inverter average switching frequency to 33% when compared to traditional sine PWM. To effectively implement the SPM modulation, a fast dynamic control of dc link voltage is required. For that a coordinated control is implemented. And also the effect of dead time on the inverter terminal voltage for a SPM modulated converter is analyzed and its effect on terminal voltage is presented. To mitigate this effect, a compensation technique based on resonant control is proposed. RMS current stress for high voltage dc link capacitor is studied and it is shown that the capacitor requirement for SPM modulation is lower than the conventional Sine Pulse Width Modulation (SPWM). To validate the proposed control scheme, a 800 W prototype is fabricated. Hardware results are presented to show the effectiveness of the implemented control scheme. 11:20AM Closed-Form Equations for Analytical Exploration and Comparison of Switching Power Losses in Flying Capacitor Multicell and Active Neutral-Point-Clamped Multilevel Converters [#1104]
This study presents closed-form formulas in order to analytically calculate, evaluate, and compare the switching power losses in flying capacitor multicell (FCM) and active neutral-point-clamped (ANPC) converters. The equations are derived on the basis of computing the switching instants of the PWM modulator exploiting the Kapteyn (Fourier-Bessel) series. In this regard, the switching power loss investigation is carried out analytically through the derived closed-form equations, and numerically through simulation results. In order to simulate the switching power losses the numeric approach using curve- fitting method is adopted. Comparative analysis and evaluation of the switching power losses are presented for both of the multilevel converters. 11:45AM Advanced Three Level Active Neutral Point Converter with Fault Tolerant Capabilities [#858]
A novel fault-tolerant power converter topology is developed based on conventional active neutral point clamped (ANPC) converter. The effect on converter performance due to open/short circuit faults of power devices is investigated. By leveraging the redundant leg in the proposed topology, the lost voltage vectors in the space vector diagram can be restored. This new fault-tolerant topology is capable of maintaining the full output voltage and maximum modulation index during postfault operation stage. A 25-kW converter prototype based on using 1.2kV SiC MOSFETs has been built in the laboratory, and the experimental results verified the efficacy of the proposed fault- tolerant ANPC converter. AC-AC Converters I Thursday, September 22, 10:30AM-12:10PM, Room: 202E, Chair: Pat Wheeler, Mattia Ricco 10:30AM A Novel Highly Reliable Three Phase Buck-Boost AC-AC Converter [#75] Ashraf Ali Khan and Honnyong Cha, Kyungpook National University, Korea (South) In this paper, a novel three-phase buck-boost ac-ac converter is proposed. It requires only three inductors and six switches. The proposed converter has no current shoot-through related problems and eliminates the PWM dead times, which results in greatly enhanced system reliability. The proposed converter allow the use of MOSFET without conducting body diode, therefore the reverse recovery issues and related loss of MOSFET body diode can be eliminated. The use of MOSFET in conjunction with external diode reduces the power loss, and the converter can be designed at higher switching frequency to reduce the volume of passive components. A 1 kW hardware prototype of the proposed three-phase buck-boost ac- ac converter is fabricated and tested. The detailed analysis followed by experimental results are provided to prove the novelty of the proposed converter. 10:55AM Hybrid Bidirectional AC/AC Multilevel Converter [#1463]
A new bidirectional multilevel converter topology called Hybrid Multilevel Converter (HMC) suitable for high power AC/AC applications is presented. It is based on cascaded connection of multiple half-bridge submodules in addition to nine thyristor-based low-frequency and soft-switched unfolders in a three-phase version. Compared with a conventional modular multilevel converter (MMC), HMC requires less number of capacitors and IGBTs and also does not inherit the internal unwanted circulating current which obviates the necessity of arm inductors. A control strategy is developed which guarantees the capacitor voltage balancing in different operating conditions. The practicality of the modified SMMC, as well as the effectiveness of the voltage balancing control, is confirmed by simulation. 11:20AM A Reliable Cascaded AC-AC Converter [#356]
This paper presents a new type of cascaded PWM ac-ac converter with phase-shift PWM control. It can reach high output voltage by cascading single-phase units of low voltage rating devices. The proposed converter does not sense current/voltage polarity, and does not require current/voltage sensors and lossy snubbers for commutation, thereby the control complexity can be decreased. It has no shoot- through problem and eliminates the PWM dead times, which leads to greatly enhanced system reliability. The phase shift PWM control is also proposed for the proposed converter to reduce the volume of passive components, and current and voltage ripples. In order to verify the robustness of the proposed converter, a 1 kW hardware prototype converter having two-unit cell structure is fabricated and tested 11:45AM Parallel AC-AC Three-Phase with Shared-Leg Converters [#773]
Two parallel ac-ac three-phase to three-phase with shared-leg converters are proposed in this paper. They are composed of two parallel three-phase rectifiers, two parallel three-phase inverters, where each group of rectifier and inverter sharing one or two legs, and one or two dc-links. Suitable modelling and control strategy of the system are developed. Compared to the conventional three-phase to three-phase dc-link converter, the proposed topologies permit to reduce: the current and power ratings of the power switches, total harmonic distortion (THD) of grid current and, the semiconductor and dc-link capacitor losses. Simulated and experimental results are also presented in order to validate the analyses. Modular Multilevel Converters (MMC) II Thursday, September 22, 10:30AM-12:10PM, Room: 202B, Chair: Juergen Biela, Grain Adam 10:30AM A Series HVDC Power Tapping Using Modular Multilevel Converters [#251] Binbin Li, Mingxu Guan, Dianguo Xu, Rui Li, Grain Philip Adam and Barry Williams, Harbin Institute of Technology, China; University of Strathclyde, United Kingdom The concept of HVDC taps drawing small amount of power from HVDC lines to the rural places has been considered for several decades. Most of the earlier tap converters were limited by its loss, cost, reliability, and control difficulties. However, in this paper, the emerging modular multilevel converter (MMC) is adopted as the series HVDC tap, which reveals significantly improved performance and feasibility. Circuit structure and operating principle of this tap are presented, and the control considerations are also discussed. Simulations are given to demonstrate effectiveness of the MMC tap and the proposed control strategies. This tap topology is very promising to find practical use in future HVDC tapping applications. 10:55AM A Zero-sequence Voltage Injection Control Scheme for Modular Multilevel Converter Under Submodule Failure [#234]
In this paper, a modulation strategy based on zero-sequence voltage injection is proposed for module multilevel converter (MMC). By the proposed method, the remaining capacitor voltages not vary and the line-to-line voltages are balanced. This method is easy to be implemented by adjusting the voltage injection coefficient when SM fault occurs. The coefficient of injected zero-sequence voltage is designed by the number and position of the fault submodules (SMs) and the fault tolerant capability of this method are also discussed. The effectiveness and advantages of proposed method are confirmed with simulation and experiment. 11:20AM An Interconnected Observer for Modular Multilevel Converter [#891]
Modular multilevel converter is an attractive topology for transformer less high voltage applications due to its capability to reach high voltage levels by the use of power semiconductors. Each submodule can be considered as a controlled voltage source where capacitors voltages should be maintained at a certain level for proper operation of the MMC and for fault detection and protection purposes. Besides, the minimization of the circulating current, which does not flow to the load, is crucial to achieve stable and efficient operation of the MMC. Thus, this paper presents a novel Interconnected Observer based Model Predictive Control for a single phase MMC. The newly designed observer is used to estimate the capacitors voltages using the circulating and load currents. This approach introduces the capacitance value of the cell capacitors as a parameter uncertainty toward making the system performance robust with anonymous constant parameters. The estimated capacitors voltages are then used by the proposed MPC algorithm to achieve stable and balanced voltage and for current control with reduced circulating current in various operating conditions. Simulation studies are performed in Matlab Simulink environment to verify the proposed design. 11:45AM DC Bus Balancing Control Techniques for the Cascaded Neutral Point Clamped Modular Converter [#920]
This paper investigates different compensation methods for neutral point potential deviation based on modular multilevel single star neutral point clamped-bridge converter. Theoretical analysis indicates injecting an offset for a cell can effectively decrease this deviation, so this research presents different offset-compensation techniques, and evaluates their output performance. Besides, this research also presents a hierarchical voltage balancing control to efficiently process the power flow among cells. Laboratory test results are provided to verify their effectiveness. DC-DC Isolated: Resonant Thursday, September 22, 10:30AM-12:10PM, Room: 102C, Chair: Dragan Maksimovic, Yan-Fei Liu 10:30AM Step-Down Impedance Control Network Resonant DC-DC Converter Utilizing an Enhanced Phase-Shift Control for Wide-Input-Range Operation [#1447] Jie Lu, Ashish Kumar and Khurram Afridi, University of Colorado Boulder, United States This paper introduces an isolated step-down impedance control network (ICN) resonant dc-dc converter that utilizes enhanced inverter and rectifier phase-shifts to achieve both soft-switching and output voltage regulation. Compared to previously presented ICN converters, which utilize burst-mode control to achieve output voltage regulation, this ICN converter with the proposed enhanced phase-shift control has dramatically reduced output capacitance requirement, simplified the input EMI filter design, and improves converter efficiency. A prototype 1-MHz, 120-W step-down ICN resonant converter designed for an input voltage range of 18 V to 75 V, an output voltage of 12 V, and a 10:1 output power range has been designed, built and tested with both burst-mode control and the proposed enhanced phase-shift control. When operated with the enhanced phase-shift control, the prototype ICN converter achieves a peak efficiency of 95.7% and maintains full-power efficiency above 91.7% across its 4:1 input voltage range. Compared to when operated under burst-mode control, the ICN converter with enhanced phase-shift control reduces converter losses by up to 30% and reduces the output capacitance requirement by two orders of magnitude. 10:55AM Soft-Switching Push-Pull Converter with Parallel Resonant Link and Buck-Boost Capability [#1017]
A partial resonant push-pull converter with buck-boost capability is proposed. Magnetizing inductance of the three-winding transformer and three capacitors are used to form a parallel LC resonant link. The capacitors create a Zero Voltage Switching (ZVS) condition at turn-on and reduce the turn-off loss for all switches. Although the converter is not current-fed, there is no dc offset in the input current, thereby eliminating the saturation problem that is common to conventional push-pull converters. An analytical approach is developed to establish a relationship between link parameters, input and output voltages, and link frequency. Experimental results are included to corroborate the design and operation.
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