This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination. IEEE TRANSACTIONS ON PLASMA SCIENCE 1 A Fast and Series-Stacked IGBT Switch With Balanced Voltage Sharing for Pulsed Power Applications Mostafa Zarghani, Sadegh Mohsenzade, and Shahriyar Kaboli Abstract— The series configuration of fast semiconductor switches seems to be the key component in the high-voltage and fast rising time pulse generation. In this approach, two important issues must be considered. The first is to provide a safe operating condition for the switches in transient intervals. The second is to design a gate drive system with the capability of driving a large number of discrete devices simultaneously. The aim of this paper is to obviate these two requirements. First, different factors affecting the unbalanced voltage sharing between the series switches are discussed. In this investigation, the switch-to-ground parasitic capacitance effect has been recognized as the major effect on the unbalanced voltage sharing in the transient interval. Two schemes for abating this effect are proposed. To solve the unbalanced voltage distribution, the structure with a snubber circuit in the clamp mode operation is suggested. This scheme can be used for any number of switches without destructively affecting their behavior. In addition, the output pulse with a fast rising time could be obtained by the proposed gate drive system. In order to evaluate the operation of the proposed structure, a stacked switch with the voltage capability of 36 kV is tested experimentally. The characteristics of the obtained pulse are the fast rising time (69.5 ns) with the dV/dt of 460 kv/μs and the wide range of the pulsewidth adjusting to 0.5–15 μs. In addition, the voltage variance of the switches level in the series structure is about 10%. Index Terms— Pulsed power supplies, semiconductor devices, solid-state switch, snubber circuit. I. I NTRODUCTION P ULSED power supplies are widespread in industrial applications. Some of their applications are food processing [1], water treatment [2], medical linear accelera- tor [3], and plasma [4]. Common structures reported in the literature for the pulsed power supplies include the Marx pulse generator, structures that combine a high power switch and a boost transformer, and Pulse Forming Network (PFN)- based structures with a discharge switch. Modern structures for Marx-type pulsed power supplies are reported in [5]–[8]. Marx structures similar to those in [6] usually lead to high-quality output pulse, but their main problem is the use of twice the number of switches. The modular types of Marx pulse genera- tor similar to the structure reported in [7] need several isolated Manuscript received December 13, 2015; revised March 6, 2016 and April 30, 2016; accepted May 14, 2016. (Corresponding author: Shahriyar Kaboli.) The authors are with the Sharif University of Technology, Tehran 11365-11155, Iran (e-mail: mostafa.zarghani@gmail.com; sa.mohsenzade@yahoo.com; kaboli@sharif.edu). 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/TPS.2016.2574126 power supplies for capacitor charging. Multiple primary cur- rents and the parasitic inductance and capacitance are the main hindrances in the pulsed power supplies with a boost trans- former. In order to reduce the effect of the boost transformer parasitic elements, solutions such as the matrix transformer [9] are reported in the literature. However, output pulse with a high quality and fast rising time could not be achieved easily. The PFN-based pulsed power supplies have many disadvantages such as poor output pulse quality and fixed pulsewidth. In addi- tion, twice switching capacity is necessary in the matched load supply [10]. Utilizing semiconductor switches in the pulsed power supplies has greatly enhanced their specifications. The most important characteristics of the pulsed power supply such as lifetime, output power, repetition rate, and the output pulse shape depend on the switching element [11]. In addition, semiconductor switches provide compactness and mobility of the pulsed power supplies. The main problem of the semiconductor switches is the limited nominal voltage and current. Moreover, the nominal power increment in the semi- conductor switches often abates their unique properties [12]. Advantages achieved by the semiconductor switches persuaded the researchers to devise the series or parallel structure of the semiconductor devices to gain higher ratings in addition to save the merits of a single device. Almost all types of semicon- ductor switches are overcurrent tolerant in the transient interval but are not overvoltage tolerant. Furthermore, paralleling most of the semiconductor devices is easy because of the positive thermal coefficient [13]. Inversely, the overvoltage situation is fatal for such devices. On the other hand, in high-voltage pulse generation with a fast rising time and a highly flattened top, using a direct switch type without any boost transformer and PFN seems to be the unique approach. Therefore, different structures for increasing the voltage capability and equal voltage distribution of the semiconductor devices are reported in the literature. In this paper, the proposed clamp mode snubber circuits applied to each switch are recognized as an effective solution for switch voltage balancing. The power loss of the proposed snubber circuits is acceptable. They are decoupled from the switch in the ON-state interval. Hence, no destructive effect on the switching speed is expected. Moreover, in this paper, switch-to-ground parasitic capacitance effect causing unbal- anced voltage sharing is discussed and solutions to reduce this effect are proposed. In addition, fast rising time is obtained by the proposed gate drive system. Through this proposal, acceptable synchronized operation of the devices is provided 0093-3813 © 2016 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.