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:
- WBG in Traction Application
- Single Phase Rectifiers
- Multilevel Converters
- DC-DC Converters II
Tingting He, Li Li, Jianguo Zhu and Zheng Linfeng, FEIT, University of Technology, Sydney, Australia This paper presents a novel model predictive sliding mode control (MPSMC) strategy for a three-phase grid connected AC/DC converter. The grid current is predicted for controlling the active and reactive power flows for the next sampling time instead of predicting them directly. This MPSMC scheme employs a sliding mode control (SMC) algorithm to calculate the reference values of active and reactive powers in the cost function. The reaching, existing and tracking conditions are analyzed to ensure that the designed sliding surface and control law are effective to control the system. The simulation results by Matlab/Simulink show that the MPSMC strategy is able to meet the system requirements of active and reactive powers, as well as the DC output voltage. Compared with the results obtained from the conventional model predictive PI control (MPPIC) scheme, the proposed strategy can improve the dynamic performance dramatically in terms of the response speed under system disturbances, such as varying output voltage and load demand. 2:20PM A Novel Virtual Synchronous Generator Control Strategy Based on Improved Swing Equation Emulating and Power Decoupling Method [#756]
A novel practical virtual synchronous generator control strategy considering the differences between inverters and real synchronous generators is proposed in this paper. The proposed control strategy improves the emulation method of damping power in swing equation, which does not need a PLL and in the meanwhile eliminates the effect on the droop coefficient caused by the traditional constant damping factor. Avoiding a differential term, a virtual synchronous impedance is implemented in synchronous rotating reference frame in order to tackle the issue of power coupling caused by the high line impedance ratio R/X. Furthermore, a novel power decoupling method by introducing current compensation into the current loop is proposed to eliminate the power coupling caused by the large power angle, which can noticeably eliminate the power dynamic oscillation and steady-state error. Finally, both the simulation and experimental results validate the effectiveness of the proposed method. 2:45PM Virtual Impedance-Based Active Damping for LCL Resonance in Grid-Connected Voltage Source Inverters with Grid Current Feedback [#757]
Grid-connected Voltage Source Inverter (VSI) with LCL filters, controlled by proportional-resonant compensator in stationary reference frame, is very popular in utility application for its better power quality feature, while the inherent LCL resonance characteristic limits the control loop bandwidth and threatens the system stability. The active damping is essential to dampen the LCL resonance. This paper investigates the active damping method with only grid current feedback. Compared with the most widely used capacitor current feedback active damping, this novel method avoids the use of extra sensors to detect the capacitor current, which possesses the merits of lower cost and higher reliability. By performing the equivalent control block diagram transformation, it is revealed that a virtual impedance in series or parallel with the grid-side inductor can ideally be implemented with specific active damping controllers, which also comprehensively reflects the physical circuit property of grid current feedback active damping. However, the second-order derivative terms are needed in the ideal forms of the active damping controllers which can hardly be realized in practice. To deal with this issue, a second-order transfer function is proposed to approximate the second- order derivative term in the required frequency range for realizing the similar LCL resonance damping performance. Further, a straightforward design method to determine the parameters of the active damping controller is introduced. Finally, the effectiveness of the proposed control method and relevant design strategies are verified both in time and frequency domain. WBG in Traction Application Wednesday, September 21, 1:30PM-3:10PM, Room: 102D, Chair: Burak Ozpineci, Anand Sathyan 1:30PM Component Design and Implementation of a 60 kW Full SiC Traction Inverter with Boost Converter [#668] Arvid Merkert, Jan-Kaspar Mueller and Axel Mertens, Leibniz Universitaet Hannover, Germany In electric vehicular (EV) traction drives, Silicon Carbide (SiC) devices promise large savings in volume and weight of the converter system, especially when an inverter is combined with a boost DC/DC converter. Such a system has been designed, implemented and tested as a laboratory prototype. Detailed information on the component design is given and the prototypes characteristics are compared with a conventional Silicon IGBT based industrial system. 1:55PM Design Methodology for a Planarized High Power Density EV/HEV Traction Drive using SiC Power Modules [#1654]
This paper provides a methodology for overall system level design of a high-power density inverter to be used for EV/HEV traction drive applications. The system design is guided to accommodate off-the-shelf SiC power modules in a planar architecture that ensures proper electrical, thermal, and mechanical performances. Bi- directional interleaved DC-DC boost structure and a three-phase voltage source inverter (VSI) have been utilized with the primary focus on the size, weight and loss reduction of passive components. A stacked layer approach has been used for a unique PCB-based busbar, ultra-low profile gate driver, and controller board. This holistic design approach results in a highly compact traction drive inverter with power density of 12.1 kW/L that has lower volume and weight compared to the commercially available state-of-the-art power converter systems. 2:20PM A SiC-Based High-Performance Medium-Voltage Fast Charger for Plug-in Electric Vehicles [#711]
This paper presents an isolated medium-voltage, high-power-quality and high efficiency (over 96%), fast charger for plug-in electric vehicles. The proposed fully modular fast charger uses off-the-shelf Silicon Carbide (SiC) power devices to convert the rectified single-phase 2.4 kV medium-voltage input to variable dc output. The adopted input-series-output-parallel unidirectional topology enables converter scalability in both the input voltage and the output power. Using wide bandgap (WBG) power devices enables 9 times reduction in volume and 6 times reduction in weight, compared to the state-of-the-art fast chargers, while exceeding the efficiency of the state-of-the-art fast chargers by more than 1.5%. Based on the system requirements, the appropriate converter topology was selected, its operation was simulated and validated by experiments on the developed fast charger prototype. 2:45PM An Integrated Onboard Charger and Accessory Power Converter for Traction Drive Systems with a Boost Converter [#1551]
Integrating the functionality of battery charging into the propulsion and accessory power system in a plug-in electric vehicle (PEV) can significantly reduce the component count, and thus the cost, weight, and volume for the onboard charger (OBC). Replacing silicon (Si) based power devices with wide-band-gap (WBG) devices can further increase the power density and efficiency and lower the cost as WBG device technology matures and production volume increases. In this paper an isolated, bidirectional integrated OBC and accessory power converter is presented for PEVs employing a boost converter in the traction drive systems and is based on an active front converter (AFC) and a phase shifted dual-active H-bridge converter (PHDAHBC). The AFC utilizes the traction drive inverter, motor, and boost converter and the PHDAHBC is comprised of the transformer and high voltage converter of the 14 V accessory dc-dc converter and an additional H-bridge converter. Experimental results are included for a 6.9 kW OBC integrated into a 60 kW traction inverter with a boost converter using silicon carbide (SiC) MOSFETs and Schottky Barrier Diodes (SBDs). Single Phase Rectifiers Wednesday, September 21, 1:30PM-3:10PM, Room: 202E, Chair: Adam Skorek, Euzeli Santos Jr. 1:30PM Current-stress Reduction of the Neutral Inductor in a Rectifier with Two Outputs [#246] Wen-Long Ming and Qing-Chang Zhong, The University of Sheffield, United Kingdom; Illinois Institute of Technology, United States In this paper, a recently-reported single-phase rectifier with two outputs (RECTO) is further improved to reduce the current stress of the neutral inductor in the rectifier. The reduction is achieved by moving the neutral inductor away from the path of the grid current. As a result, the inductor only carries the differential current of the dual loads. Since the maximum value of the differential current is much smaller than that of the grid current, the current stress of the neutral inductor can be significantly reduced, and the size of the inductor becomes much smaller, which helps improve the power density of the RECTO. In theory, the current stress can be reduced by at least three times and the inductor size by at least nine times. It is worth noting that the current stress of the switches and the other features of the RECTO, e.g., operation principles, independent DC outputs and unity power factor, are not affected. Comparative experimental results are presented to demonstrate the reduction. 1:55PM Single-stage AC/DC Dual Inductor BCM Current-Fed Push-Pull for HB-LED lighting applications [#447]
A single-stage, AC/DC driver for High Brightness Light-Emitting Diodes (HB-LED) with galvanic isolation is presented in this paper. The driver is based on a Dual Inductor Current-fed Push-Pull (DICPP) converter with each inductor operating in Boundary Conduction Mode (BCM). The interleaving between the two inductors makes possible for the converter to reduce the high input current ripple of a BCM. Moreover, it is fully compliant with IEC 1000-3-2 Class C, and it is also able to achieve high Power Factor (PF). Moreover, the low component count, simplicity and overall outstanding characteristics make this topology suitable for medium power range HB-LED drivers in low cost applications. Finally, the proposed topology has been tested on a 90W prototype for the full range of the US single-phase line voltage, feeding several strings of HB-LED, with an output voltage of 48V at full load. The prototype achieves a maximum efficiency of 92% with 0.99 power factor, 8% THD at full load and guarantees good quality light. 2:20PM Asymmetric Single-Phase Current Source Rectifiers [#1535]
In this work it is presented a family of six single-phase Current Source Rectifiers (CSR) topologies with asymmetric structures. The topologies present reduced number of active switches and high power factor with low harmonic distortion. Three of the shown structures represent a simplification of full-bridge CSR, replacing two switches from the original topology by two diodes. The other three structures are composed by only one switch, based on single-switch CSR and buck-type CSRs. Details of control strategy and modulation are presented. Experimental results are provided for the full-bridge derived topologies, while simulation results are presented for the other topologies to validate the effective operation of the structures. 2:45PM A Bridgeless Controlled Rectifier for Single Split-Phase Systems [#1001]
An unidirectional single-phase three-wire rectifier is proposed in this paper. Such a proposed topology is composed of a non-controlled leg, two controlled legs and a capacitor bank. A suitable model and control strategy of the system, including a synchronization method, are proposed as well. The synchronization method, associated with the PWM strategy, imposes the grid currents to have the same phase angle of the generated voltages by rectifier. This method ensures sinusoidal grid currents and mitigate the zero-crossover distortions normally caused by the use of diodes. A comprehensive comparison with two conventional configurations is also presented in this paper. Simulation and experimental results are also presented for validation purposes. Multilevel Converters Wednesday, September 21, 1:30PM-3:10PM, Room: 202B, Chair: NingYi Dai, Marcello Pucci 1:30PM Modulation Method for Single-Phase Six-Switch Five-Level ANPC Inverter [#141] Lei Kou, Hongliang Wang, Yan-fei Liu, Paresh C. Sen and Yan Zhang, Queen's University, Canada The Five-Level Active-Neutral-Point-Clamped (5L-ANPC) inverter is one of the most popular topologies among five-level inverters since it combines the features of Flying-Capacitor (FC) type and Neutral-Point-Clamped (NPC) type inverters and was commercially used for industrial applications. This paper proposes a novel modulation strategy for a Six-Switch 5L-ANPC (6S-5L-ANPC) topology to keep voltages of DC-link capacitors and FC balanced. The equations to calculate the FC capacitance in active and reactive power conditions are also provided. Simulation and experiment have been carried out to demonstrate the effectiveness of the proposed modulation technique. 1:55PM Modified SVPWM to Eliminate Common-Mode Voltages for Five-Level ANPC Inverters [#461]
In this paper, a novel common-mode voltage (CMV) elimination scheme is proposed for five-level active neutral-point clamped (5L-ANPC) inverters, which is based on the space vector PWM (SVPWM). The proposed SVPWM scheme utilizes only 19 voltage vectors producing a zero value of CMV among the whole 125 voltage vectors of the 5L-ANPC inverter. This scheme is also able to control all capacitor voltages by selecting redundant switching states of the inverter appropriately. Therefore, the inverter can be supplied by a single DC source such as a simple diode rectifier. The validity of the proposed SVPWM scheme is verified by simulation results. 2:20PM THD and Efficiency improvement in Multi-Level Inverters through an Open End Winding Configuration [#966]
A new approach, based on a current controlled Asymmetrical Hybrid Multilevel Inverter (AHMLI), is proposed to reduce power losses and output current distortion on Multi-Level Inverters (MLI) used in AC motor drives, STATCOM devices, Photovoltaic and Wind generators. A key feature of the proposed approach is that the AC machine (motor or transformer) is operated in an open- end winding configuration, being supplied on one end by a main Multi-Level Inverter and, on the other side, by an auxiliary Two-Level Inverter (TLI). The MLI controls the main active power stream; it operates at a low switching frequency and can be equipped with very low on-state voltage drop IGBT devices. The auxiliary TLI is instead operated according to a conventional high frequency two-level PWM technique and acts as an active power filter providing only a null-average power to the AC machine. As the DC bus voltage of the TLI is remarkably lower that that of the main MLI, the auxiliary inverter can be equipped with low switching losses IGBTs, or even Power MOS devices. Simulations and experimental results confirm that using the proposed approach, the phase current harmonic content is remarkably reduced, the efficiency is increased and in motor drive applications, the torque ripple is mitigated. 2:45PM A Source-Type Harmonic Energy Unbalance Suppression Method Based on Carrier Frequency Optimization for Cascaded Multilevel APF [#292]
Cascaded H-bridge multilevel converter based active power filter can compensate high-order harmonics (17th-50th) in middle-high voltage system with relatively lower switching frequency, but at the same time, a special DC capacitor energy unbalance problem is caused. When the compensation current frequency is close to the witching frequency of the H-bridge cell, harmonic power coupling will lead to the divergence of DC voltages, which is called source-type harmonic energy unbalance in this paper. A carrier frequency optimization method is proposed to suppress the unbalance. This method decouples the harmonic voltage with the output current and minimizes the DC voltage ripple only by appropriately adjusting the carrier frequency. The method is verified by the presented simulation results. DC-DC Converters II Wednesday, September 21, 1:30PM-3:10PM, Room: 102C, Chair: Yan-Fei Liu, Lixiang Wei 1:30PM Small-Signal Model and Control of the Interleaved Two-Phase Coupled-Inductor Boost Converter [#483] Brendan C. Barry, John G. Hayes, Marek S. Rylko, Robert Stala, Adam Penczek, Andrzej Mondzik and Robert T. Ryan, University College Cork, Ireland; dtw Sp. z o.o., Poland Coupled-inductor boost converters are under development for high-current, high-power applications ranging from automotive fuel cells to photovoltaics. This paper presents the small-signal analysis of a coupled-inductor boost converter operating in both CCM and DCM. Due to the complexity of operation of a coupled-inductor boost converter operating in DCM, several small-signal models must be derived. Controllers for the converter are developed using the resulting small-signal models. Experimental validation of these controllers is presented from a 1 kW coupled-inductor boost converter laboratory prototype. 1:55PM A Robust Design Framework for Stable Digital Peak Current-Mode Control Under Uniform Sampling [#930]
Fully digital current-mode control (DCMC) has become popular in high frequency applications, primarily because of using the uniform sampling rate for both the voltage and current loops. This requires a lower sampling analog-to-digital converter (ADC), in which the inductor current is sampled once in every switching cycle and the ripple current is emulated in the digital domain. Thus, this remains an important concern about the selection of the emulated current slope. Earlier approaches attempt to extract the actual slopes of the inductor current either using model predictive algorithms or using online computation by considering a few extra current samples. These methods are highly sensitive to system parameters and increase computational complexity. Moreover, this paper reports that even if accurate slope information is available, the uniform voltage-loop sampling often leads to sub-harmonic instability, even with the duty ratio less than 0.5. Using discrete-time models, design methods show that the required stabilizing slope is different from the actual current slope, and the slope magnitude needs to be increased for a higher controller gain. This provides a robust design framework to devise a stable DCMC technique for fast recovery, without attempting to find the actual slope information. A buck converter prototype is made and the proposed controller is implemented using an FPGA device. 2:20PM Modeling and Decoupled Control of a Non-isolated High Step-up/down Bidirectional DC-DC Converter [#434]
Bidirectional DC-DC converters play a very important role in energy storage systems. High voltage conversion ratio, high efficiency and economy are challenging issues for the research and development of advanced bidirectional DC-DC converters. In this paper, the modeling and control of a new non-isolated high step-up/down bidirectional DC-DC converter is studied. This converter is a combination of buck-boost and dual-active-half-bridge converter. It features wide-range high voltage conversion ratio and high efficiency due to full soft switching. However, the circuit coupling causes troubles in control stability. For instance, in island boost mode, oscillation easily occurs if output voltage of high-pressure is still directly regulated by shifted phase. Hence A dynamically accurate enough model is required for analysis and more stable control method is needed. For the modeling, scholars have made some research on calculating power delivered by the transformer with its series inductor current, but they have not taken the series inductor current as a state variable in full frequency domain. Such methods achieve good outcomes in steady-state, but are at a cost of dynamic inaccuracy more or less. In this paper, an average modeling technique which considers transformer series inductor current as a state variable in full frequency domain for dynamic accuracy is proposed. A decoupled control is also proposed to achieve a leap in stability. Simulation and experiment results are also presented to verify the proposed average model and the decoupled control. 2:45PM Non-Isolated High-Gain Three-Port Converter for Hybrid Storage Systems [#1140]
This work proposes a non-isolated power electronic topology to interface two distinct electrical energy storage units to a DC link, resulting in a Hybrid Storage System. The proposed solution, called Series-Parallel Connection, allows for interfacing these three ports in a simple, compact and reliable approach, based on the standard configuration of the H-bridge converter. The main advantage is that one of the storage units can be of much smaller voltage ratings than the other two, avoiding the use of multilevel or galvanic-isolated power stages. The resulting structure is compared against the most significant transformerless alternatives based on the H-bridge converter, stating their advantages and drawbacks. An analysis of the switching and conduction losses in the power switches of the proposed solution is carried out in order to state the design constraints at which this solution presents improved efficiency versus the alternatives. A final set of experiments in a 10 kW built prototype demonstrates the feasibility and states the benefits as well as the main limitations of the proposed scheme. Yüklə 2,78 Mb. Dostları ilə paylaş:
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