IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 23, NO. 6, NOVEMBER 2008 2665 A Systematic Topology Evaluation Methodology for High-Density Three-Phase PWM AC-AC Converters Rixin Lai, Student Member, IEEE, Fei (Fred) Wang, Senior Member, IEEE, Rolando Burgos, Member, IEEE, Yunqing Pei, Member, IEEE, Dushan Boroyevich, Fellow, IEEE, Bingsen Wang, Senior Member, IEEE, Thomas A. Lipo, Life Fellow, IEEE, Vikram D. Immanuel, Member, IEEE, and Kamiar J. Karimi, Member, IEEE Abstract—This paper presents a systematic evaluation approach of three-phase pulsewidth-modulated (PWM) ac–ac converter topologies for high-density applications. All major components and subsystems in a converter are considered and the interdependence of all the constraints and design parameters is systematically stud- ied. The key design parameters, including switching frequency, modulation scheme, and passive values, are selected by consider- ing their impacts on loss, harmonics, electromagnetic interference (EMI), control dynamics and stability, and protection. The com- ponent selection criteria as well as the physical design procedures are developed from the high-density standpoint. The concept of using the same inductor for harmonic suppression and EMI filter- ing is introduced in the design. With the proposed methodology, four converter topologies, a back-to-back voltage source converter (BTB-VSC), a nonregenerative three-level boost (Vienna-type) rec- tifier plus voltage source inverter (NTR-VSI), a back-to-back cur- rent source converter (BTB-CSC), and a 12-switch matrix con- verter, are analyzed and compared for high specific power using SiC devices. The evaluation results show that with the conditions specified in this paper, BTB-VSC and NTR-VSI have considerably lower loss, resulting in higher specific power than BTB-CSC and the matrix converter. The proposed methodology can be applied to other topologies with different comparison metrics and can be a useful tool for high-density topology selection. Index Terms—High density, SiC devices, switching frequency, three-phase ac–ac converter. I. INTRODUCTION I T IS OFTEN desirable to reduce the size and weight of a converter, while meeting performance and cost require- ments. In some cases, such as in aircraft applications, small Manuscript received December 1, 2007; revised May 3, 2008. First published November 25, 2008; current version published December 9, 2008. This work was supported in part by The Boeing Company and in part by the National Sci- ence Foundation—Engineering Research Center under Award EEC-9731677. Recommended for publication by Associate Editor B. Wu. R. Lai, F. Wang, R. Burgos, and D. Boroyevich are with the Center for Power Electronics Systems, Virginia Polytechnic Institute and State Univer- sity, Blacksburg, VA 24061 USA (e-mail: lairixin@vt.edu; rolando@vt.edu; wangfred@vt.edu; dushan@vt.edu). Y. Pei is with the School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, China (e-mail: peiyq@mail.xjtu.edu.cn). B. Wang is with the Department of Electrical Engineering, Arizona State University, Tempe, AZ 85287-9309 USA (e-mail: bingsen@asu.edu). T. A. Lipo is with the Department of Electrical and Computer Engi- neering, University of Wisconsin, Madison, WI 53715 USA (e-mail: lipo@ engr.wisc.edu). V. D. Immanuel and K. J. Karimi are with The Boeing Com- pany, Seattle, WA 98124 USA (e-mail: Vikram.D.Immanuel@boeing.com; kamiar.j.karimi@boeing.com). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TPEL.2008.2005381 size and lightweight is a must. The power stage is the main size and weight contributor in a converter, including power semicon- ductor device packages, cooling systems, energy storage, and filter passive components [1]. The power stage design clearly depends on the converter circuit topology. Therefore, to achieve a high-density design, it is a logical and necessary step to carry out the systematic design and evaluation for the topologies that meet the application requirements, and select among them the most suitable candidate. For three-phase ac–ac converters, such as industrial mo- tor drives, the two-level pulsewidth-modulated (PWM) voltage source inverter (VSI) with six-pulse diode front-end rectifier has become the topology of choice, due to its simplicity and rela- tively low cost. One drawback of the diode front-end topology is the low-order, low-frequency harmonics on the dc link and ac in- put line, which, consequently, requires a bulky dc-link capacitor and inductor (ac or dc) filters. In order to improve converter per- formance and achieve higher power density, many topologies for three-phase ac–ac converters or motor drives with active front-end rectifiers have been proposed and studied [2]–[11]. These topologies can generally operate with reduced passive components and an improved input current waveform. On the other hand, they may have increased loss and electromagnetic interference (EMI) noise, requiring additional cooling and fil- tering [12]. Different active front-end topologies have different loss, harmonics, and EMI characteristics, which often have con- tradictory impact on the size and performance of the converter. To achieve a high power density design for a specific application, comprehensive analysis and evaluation are needed to obtain an optimal converter topology selection. There has been considerable work on ac converter topolo- gies evaluation and high-density design [13]–[20]. The previ- ous work generally focused on specific aspects of the converter design. For instance, the steady-state current and voltage wave- forms as well as the harmonics injected to the grid for two inverter topologies were compared in [13]; device losses, input filter, and cost for three-level voltage source converters (VSCs) were discussed in [14]; different converter systems were evalu- ated in terms of the grid-side power quality and loss distribution in [15]–[17]; the efficiency of the current source and the volt- age source drive systems was compared in [18], the minimum energy storage requirement on the dc link was studied in [19] and [20]. However, when developing a new converter for high- density applications, all aspects contributing to the converter size and weight must be examined in the design, which requires that the correlation between all major design parameters be 0885-8993/$25.00 © 2008 IEEE