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: Power Converter Topologies
| P4303 Investigation of Current Sharing and Heat Dissipation in Parallel-Connected Lithium-Ion Battery Packs [#1049]
Yichao Zhang, Ruxiu Zhao, Jacob Dubie, Larry Juang and Thomas Jahns, University of Wisconsin Madison, United States; Undisclosed, United States This paper adopts a circuit model with temperature-dependent parameter values to investigate the current unbalance risk in parallel-connected lithium-ion (Li-ion) battery cells and uses this circuit model to calculate heat dissipation. P4304 A Cooperative Charging Strategy for Onboard Supercapacitors of Catenary-Free Trams [#1165]
In this paper, a cooperative charging strategy is proposed for onboard supercapacitors of catenary-free trams. The multi-module charging system consists of n buck converters connected in parallel. The parallel-input parallel-output (PIPO) charging system is modeled mathematically using the averaging method. A cooperative constant-current charging control strategy is designed using the leader-follower consensus approach, where the virtual leader represents the desired charging current for each charging module with a warm-start mechanism. The cooperative charging approach provides dual benefits of both excellent dynamic performance and good reliability. Simulation and experiment results are provided to illustrate the effectiveness of the design P4305 A High Frequency Zero-Voltage-Transition (ZVT) Synchronous Buck Converter for Automotive Applications [#1123]
Automotive applications require a wide input voltage range (4.5 V to 42 V) and high frequency operation for point-of-load low power (5 W-25 W) converters. The conventional buck converter, currently being used for this application, is simple and cost effective but it is less efficient at high switching frequency (>MHz) and noisy due to its hard-switching operation. A zero-voltage-transition (ZVT) synchronous buck converter is proposed in this paper, which features ZVS for main switches, ZCS and low voltage rating for auxiliary switches. The operating principles including ZVS/ZCS mechanism, and detailed design considerations are presented. Experimental results from a 1 MHz prototype confirm its superior performance for low power automotive applications. P4306 The Dual-Channel Magnetically Integrated Chargers for Plug-in Electric Vehicles [#1292]
In this paper, a dual-channel isolated three-phase magnetically integrated chargers (MICs) are presented for plug-in electric vehicles. The key is to apply and operate two interleaved power charging circuits, each of which is composed of one dual-active-bridge (DAB) isolated converter and one three-phase grid inverter. The proposed configuration not only offers isolated charging but also provides modular design and operation for each channel, which are useful for high-power applications in fast charging. The interleaved operation and the phase-shifted carriers enable low current ripple on battery side and better harmonic performance on grid side. Furthermore, chaotic modulation has been applied to reduce the distinct switching harmonics in spectrum, which will facilitate improving the conducted electromagnetic compatibility (EMC). The detailed design of modulation strategy and control scheme are described in this paper. Experimental results have been presented for a 1-kW laboratory prototype to verify the validity of the proposed configuration and schemes. P4307 Power-Line Impedance Modeling of Tractor-Trailer System [#1660]
This paper focuses on the channel characterization and modeling for power line communication (PLC) inside a Tractor-Trailer system. Understanding the behavior of the power line in tractor-trailer system at PLC frequency bands is quintessential for designing the PLC system to achieve desired performance. In this paper, s-domain impedance signatures for the tractor, trailer, dolly, harness and electronic control unit (ECU) has been developed by making impedance measurements of the system under different loading scenarios. The transfer function model predicting the PLC channel impedance under the given frequency band, shows good agreement between the estimated and measured data on a tractor-trailer system test bed platform Poster Session: Power Converter Topologies Tuesday, September 20, 3:00PM-4:30PM, Room: Exhibit Hall, Chair: Pradeep S. Shenoy, Leon M Tolbert P4501 An Interleaved 1-to-6 Step-Up Resonant Switched-Capacitor Converter Utilizing Split-Phase Control [#1286] Andrew Stillwell, Derek Heeger, Christopher Meyer, Sarah Bedair and Robert Pilawa-Podgurski, University of Illinois at Urbana-Champaign, United States; Army Research Laboratory, United States Hybrid and resonant switched-capacitor (SC) converters have the potential to achieve higher power densities than conventional dc-dc converters. This work presents an interleaved, 20 V to 120 V, resonant SC converter which could be used in applications that benefit from high power density and efficiency. The resonant topology of this SC converter enables a compact and efficient design that minimizes losses. We use a new split-phase control scheme that incorporates precisely timed additional transition states to increase the converter efficiency. A two-phase interleaved design increases the output power and simultaneously decreases the output ripple through harmonic cancellation. In addition to experimental evaluation of a 95.7% efficient, GaN-based prototype of this interleaved converter, an analysis of current sharing between interleaved phases is performed. P4502 Boost Composite Converter Design Based On Drive Cycle Weighted Losses in Electric Vehicle Powertrain Applications [#1409]
A weighted design optimization is introduced to minimize total loss of electric vehicle drivetrain power electronics over EPA standard drive cycles. It is shown that the net loss of the conventional boost converter can be reduced by a factor of 1.5 with this approach, while computational effort is reduced by three orders of magnitude. Even larger efficiency improvements are achieved by optimized boost composite converters: losses are reduced by factors of 4.5, 2.9, and 4.3 for US06, UDDS, and HWFET driving cycles, respectively. These design optimization results are experimentally verified with a 30 kW laboratory prototype boost composite converter, which demonstrates 98.4% average efficiency over the US06 driving cycle. P4503 Design of a Four-Phase Interleaved Boost Circuit with Closed-Coupled Inductors [#1422]
In this paper, a novel magnetic structure suitable for boost converters is proposed. Multi-phase interleaved method using coupled-inductor has gained attention in electric powertrains for electric, hybrid and fuel cell vehicles in order to achieve high power density. In fact, a four-phase boost converter using coupled inductor is used in the drive system of the Honda CLARITY. In particular, magnetic coupling method is used in coupled inductors, Loosely-Coupled Inductors (LCI) and Closed-Coupled Inductors (CCI). This study is focused on these methods, especially using the CCI. This paper presents a design method of a closed-coupled inductors using generic cores for a four-phase interleaved boost converter. In addition a comparison between the proposed topology with other conventional non- coupled methods is carried out. Furthermore, the evaluation of miniaturization is studied. As a result, the proposed method can achieve a huge reduction in the core volume and mass. P4504 Hybrid DC-DC Buck Converter with Active Switched Capacitor Cell and Low Voltage Gain [#54]
This paper proposes a novel dc-dc buck converter that is composed by an active switched capacitor cell and a conventional buck converter. The proposed converter is named as hybrid buck converter and it presents static gain from 0 to 0.5, maintaining the typical linear characteristics of the buck converter and it reduces the voltage stress on the power components. A theoretical steady state analysis to obtain the steady values of all capacitor voltages and the inductor current are presented. A generalization of the switched capacitor cell is also proposed to show the extensive applicability of this structure to dc-dc high step-down voltage ranges. Simulation and experimental results are reported herein to corroborate the proposed structure and the theoretical analysis. An efficiency result is also reported in this paper for the rated power. The prototype specification designed was: 1 kW, 600 V in input voltage and 150 V in output voltage. P4505 High Gain Resonant Boost Converter For PV Micro- Converter System [#1582]
This paper presents an isolated high-gain topology which employs resonant boost converter with coupled inductor or boost transformer for the Photovoltaic (PV) micro-converter system. The given configuration has the features of resonant soft switching, galvanic isolation, high gain and low switching losses. The proposed system uses LC series resonant tank circuit and had resonant operation both during turn-ON and turn-OFF. Further, the system operates near resonant frequency which minimizes the circulating or reactive current requirement in the resonant circuit. The proposed system operates in DCM mode with small losses during turn-OFF for the boost switch. Also, the proposed system has a wide operating voltage range for the PV source compared to existing solutions. In total, the given configuration has the benefits of coupled inductor technique, voltage doubler technique, resonant switching and galvanic isolation. Details of working principle, modes of operation and analysis with simulation and hardware results are presented in the manuscript. P4506 Design of Two-Switch Flyback Power Supply Using 1.7 kV SiC Devices for Ultra-Wide Input-Voltage Range Applications [#1686]
This paper presents the design and evaluation of a two-switch flyback power supply with ultra-wide input voltage range, fed from the floating dc bus of power electronics building blocks in medium voltage modular multilevel converter applications. Rated at 80 W, 48 V output, and operating at 50 kHz, the proposed converter uses 1.7 kV SiC devices and a planar PCB-winding transformer to achieve a low-profile form factor. Experimental results are presented for verification and evaluation purposes. P4507 A Single-Stage Interleaved LLC PFC Converter [#1223]
This paper presents a novel single-stage AC/DC converter that can achieve high power factor with reduced switching losses for semiconductor devices. The topology is derived by integrating the interleaved boost-type PFC and full bridge LLC resonant converters. Due to interleaving at the input, the converter exhibits less input current ripple compared to the existing single stage topologies. Therefore, it is suitable for applications up to approximately 500 W. A detailed analysis of the operation modes is presented. Also, a 350-W prototype is designed at (120 V) input AC voltage to verify the effectiveness of the topology. Applications requiring DC voltages vary widely, from low power, such as LED lighting, to high power, as in industrial motor drives and battery chargers. Accordingly, a unified power architecture for all applications is not practical for efficiency, size and cost optimization. The use of LED lighting system became popular due to its many advantages. The new outdoor applications such as street and flood lighting require high power (i.e. >200 W) in contrast to the low power existing LED drivers. Generally, the conventional architecture of AC/DC converters consists of two main stages; the first is current-shaping stage to improve PF and the second is to provide isolation and tight regulation over the output voltage The proposed single-stage topology integrates the interleaved boost and resonant LLC converters. Consequently, it can operate at higher power due to the use of interleaving, which significantly reduces the current ripple. Moreover, all semiconductor devices have soft switching transitions: ZVS for MOSFETs and ZCS for diodes, improving the overall efficiency. The converter achieves a peak efficiency equal to 92.3%, and high PF (0.997) at full load and nominal input voltage. P4508 Medium Voltage AC-DC Rectifier for Solid State Transformer (SST) Based on an Improved Rectifier Topology [#1337]
The implementation of a novel bidirectional medium voltage AC-DC converter based on 10kV SiC MOSFET is presented in this paper. The improved topology allows the removal of the reverse blocking silicon diode in medium voltage SiC MOSFET module. Shoot-through problems and avalanche of the integrated silicon diode in traditional medium voltage bridge-type AC-DC converters are solved, allowing zero dead-time operation with no current flowing through the body diode. The number of parasitic capacitors at each swing point are reduced by half, greatly reducing the dominant turn on losses caused by these capacitors. A unique customized four-in-one 10kV SiC MOSFET/JBS diode power module with high voltage isolation capability is developed and tested, which reduces parasitic parameters and simplifies converter complexity. Section based winding method is further used to reduce the inductor parasitic capacitance by 40%, helping to reduce the dominant turn-on losses by 13%. Anti-windup and feed forward control are implemented to achieve better performance. Soft start combining with a high voltage relay and fuse are used to limit the inrush current and overshoot voltage during the start- up process. Delta-sigma based fiber optical high voltage sensor is designed and implemented to achieve higher than 10kV voltage sensing capability. P4509 Microcontroller-Based MHz Totem-Pole PFC with Critical Mode Control [#1429]
This paper focuses on how to implement critical conduction mode (CRM) control for GaN-based MHz totem-pole PFC with a commercial low-cost microcontroller (MCU), including basic CRM operation, programmed on-time control for achieving low current THD, off-time extension for achieving ZVS for whole line cycle operation, and two-phase interleaving control for input current ripple cancellation and EMI filter size reduction. A novel but simple improvement of zero-current-detection (ZCD) based CRM control method is proposed to solve signal processing de-lay issue to realize CRM operation for MHz totem-pole PFC. A simple but very accurate on-time calculation method is also pro-posed for implementing programmed on-time control at MHz high frequency. The result of aforementioned control function integration and implementation is demonstrated on a 1.2kW GaN-based MHz totem-pole PFC prototype. P4510 Three-Phase Isolated DCM SEPIC Converter for High Voltage Applications [#585]
The analysis of an isolated single-stage three-phase ac-dc converter with high power factor, based on the modularity of dc-dc SEPIC converters operating in discontinuous conduction mode is presented in this paper. The ac input is star- connected while the output of the modules are series connected. Doing so, the converter can provide a high step-up ratio and, consequently, besides high output voltage, a natural unity power factor is achieved. A review of the PFC three- phase SEPIC converters is performed, and discussion regarding to the advantages and drawbacks of the proposed connection when compared to previous solutions is made. Additionally, experimental results for a 4 kW, 380 V line-to-line input voltage and 1200 V output voltage laboratory prototype are presented in order to validate the analysis. P4511 Single Phase Precharge Control Method for Active Front End Rectifier [#1595]
Active front end rectifiers (AFE) are widely used in various industrial area applications. In these types of systems, AC pre-charge circuit, output LCL filter and power module switches are the three most critical power segments. AC pre-charge circuit design is often related to an overall high component volume and cost. Many manufacturers adopt mechanical contactors or breakers between the utility connection point and the rectifier in order to ensure a smooth pre-charge of the DC bus capacitors. Since these mechanical components are typically associated with lower reliability and increased size, the power density and lifetime of the whole system gets affected significantly. This paper proposes a simple solid state pre-charge circuit for AFE rectifiers. Solid state pre-charge circuit offers a fairly simple control while reducing the inrush current for both LCL filter and DC bus capacitors. This method also demonstrates the following advantages: 1) increased lifetime, 2) smaller foot print 3) lower cost. Basic operating theory and circuit analysis along with simulation and experimental results are presented in the paper to demonstrate the effectiveness of the proposed method P4512 Adaptive Controlled-type Zero-voltage-switching Inverters with Bandwidth Limitation [#927]
A high performance inverter requires high power density, high reliability, and low cost. An adaptive controlled-type soft-switching technique achieves high efficiency and requires no additional power devices or magnetic components but with inherent frequency variation. Based on the general full-bridge inverter topology, the change in frequency under various modulation modes and load properties are studied. In order to narrow the frequency variation range, a continuous current mode (CCM) with bandwidth limitation control scheme is proposed. An adaptive controlled-type zero-voltage switching inverter with analog- digital control platform is designed and built to verify the proposed control scheme. The experimental results show that the proposed current modulation scheme has fixed switching frequency. P4513 Half Bridge NPC Inverter and Its Three Phase Application with Constant Common Mode Voltage [#1291]
In the transformerless grid connected photovoltaic system, the inverter is the main component. In order to improve the efficiency of the inversion system, several topologies have been applied, among which three level NPC inverter is a kind of popular application. Because the three level NPC inverter has the advantages of low switching losses, good common mode behavior and the small output distortion. This paper proposed a kind of novel three level half bridge NPC inverter which only applies four switches with a constant common mode voltage. Compared to the traditional half bridge NPC inverter, the proposed topology consumes less devices and has a lower conducting losses. The common mode model of the novel topology is analyzed which has verified the good common mode behavior. The three phase extended topology of the proposed inverter is also introduced with a novel modulation strategy. With the proposed modulation strategy, the three phase inverter has a constant common mode voltage. Finally, the simulation and experimental results illustrated the theoretical findings. P4514 Interleaved Auxiliary Resonant Snubber for High-Power, High-Density Applications [#1460]
Power density has become increasingly important for applications where weight and space are limited. New wide-bandgap (WBG) devices, combined with softswitching, now allow inverters to shrink in size by pushing to higher switching frequencies while maintaining efficiency. This paper proposes a novel interleaved auxiliary resonant snubber for high-frequency soft-switching to reduce volume while maintaining efficiency. The design of an auxiliary resonant snubber is discussed; this allows the main GaN MOSFETs to achieve zero voltage switching (ZVS). The auxiliary switches and SiC diodes achieve zero current switching (ZCS). While soft-switching minimizes switching loss, conduction loss is simultaneously reduced for high-power applications by interleaving two high frequency legs. P4515 Three-Phase Four-Wire Inverters Based on Cascaded Three-Phase Converters with Four and Three Legs [#1027]
This paper presents three-phase converter topologies for four-wire systems. The converters are series connected by three-phase transformers with accessible neutral. They possess a common dc-link, which is the power supply of the system, and two or more converters, where one of them is connected directly to the ac system, and the others cascaded through three-phase transformers. The three-phase transformers have turn ratios that are calculated in order to maximize the number of levels produced by the inverters. The Level-Shifted Pulse Width Modulation technique is developed for two and three cascaded converters, and a control system is used to set the electrical grid currents on desired values. Simulation and experimental results are exposed for configurations with two cascaded converters, each one with either three or four legs. P4516 Optimal Switching Counts Modulation of H7 Current Source Inverter [#1270]
The current source inverter (CSI) has some application restrictions, especially for the power efficiency problem. The H7 current source inverter is a promising topology since it provides a shunt-connected switching path and significantly reduce the power dissipation. This paper reviews the already published H7 CSI configuration character with its modulation strategy in theory and proposes an optimal modulation scheme which has the minimized hard switching counts. In addition, the grid-tied operational principle has been discussed. The proposed modulation strategy could reduce the working power dissipation, simplify the configuration of the shunt-connected switch, and meanwhile guarantee the zero current switching ability for the rear-end CSI circuitry. The switching counts and hardware cost are compared between the different modulation schemes to prove the superiority of the proposed optimal switching counts modulation strategy. The simulation and experimental results verified the theoretical findings.
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