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A New Diode Rectifier Type Utility Interface with Clean Power Characteristics
Sewan Choi,Prasad N. Enjeti 한국정보과학회 1996 Journal of Electrical Engineering and Information Vol.1 No.4
In this paper, a new active inrerphase reactor for twelve-pulse diode rectifiers is proposed. In this scheme, a low kVA (0.02 P。 (PU)) active current source injects a triangular current into an interphase reactor of a twelve-pulse diode rectifier. The proposed system draws near sinusoidal input currents from the utility with less than 1% THD is suitable for powering larger kVA ac motor drive systems. Detailed analysis of the proposed scheme along with design equations is illustrated. Simulation results verify the concept. Experimental results are provided from a 208V, 10kVA diode rectifier system.
A Wide Input Range Active Multi-pulse Rectifier For Utility Interface Of Power Electronic Converters
Jaehong Hahn,Prasad N.Enjeti,In-Gyu Park 전력전자학회 2001 ICPE(ISPE)논문집 Vol.2001 No.10
In this paper, a wide input range active multi-pulse rectifier for utility interface of power electronic converters is proposed. The scheme combines multi-pulse method using a Y-A transformer and boost rectifier modules. A current control scheme for the rectifier modules is proposed to achieve sinusoidal line currents in the utility input over a wide input range of input voltage and output load conditions. A design example is included for a 208V to 460V input, 700Vdc, 10kW output rectifier system. Simulation results are shown.<br/>
Sewan Choi,Prasad N.Enjeti,Honghee Lee 전력전자학회 1995 ICPE(ISPE)논문집 Vol.1995 No.10
In this paper, a new multi-pulse diode rectifier system is proposed for high power motor drives The proposed approach draws near sinusoidal currents from the utility line with 5th, 7th, 11th, 13th, 17th and 19th harmonics eliminated. A method to extend the conventional 12-pulse rectifier to a 24-pulse system is proposed.. With the addition of two controlled switches such as IGBT's, the pulse number is extended beyond 24 pulses. A generalized PWM technique is presented and an example 48-pulse system is demonstrated Simulation results verify the proposed concept and experimental results are provided from a 208V, 10kVA rectifier system.
Reduced Active Switch Front-End Multipulse Rectifier With Medium-Frequency Transformer Isolation
Sandoval, Jose Juan,Krishnamoorthy, Harish Sarma,Enjeti, Prasad N.,Choi, Sewan IEEE 2017 IEEE TRANSACTIONS ON POWER ELECTRONICS - Vol.32 No.10
<P>This paper presents a reduced switch count multipulse rectifier with medium-frequency (MF) transformer isolation. The proposed topology consists of a three-phase push-pull based ac to dc rectifier with a MF ac link employing two active switches. A three-phase, five-limb, multiwinding MF transformer is employed for isolation. The secondary side of the transformer is connected in a zig-zag configuration and is fed to two six-pulse diode rectifiers, achieving 12-pulse rectifier operation. The primary advantage of the proposed system is reduction in size/weight/volume compared to the conventional 60 Hz magnetic transformer isolation rectifier system. Operating the transformer at 600 Hz is shown to result in three times reduction in size. Furthermore, the proposed system employs only two active semiconductor switching devices operating under a simple pulse width modulation scheme. Also, the zig-zag transformer connection helps to balance leakage inductance on the secondary side. Detailed analysis, simulation, and experimental results on a 208V(l-l), 3.15 kW laboratory prototype are presented to validate the performance of the proposed approach.</P>
Kim, Jang-Hwan,Sul, Seung-Ki,Enjeti, Prasad N. IEEE 2008 IEEE transactions on industry applications Vol.44 No.4
<P> In a three-phase four-wire utility system, three-phase unbalanced loads and many single-phase nonlinear loads result in a neutral line current that is zero-sequence current. To deal with unbalanced and nonlinear loads in a high power system, this paper suggests a multilevel four-leg pulsewidth modulation (PWM) voltage-source inverter (VSI) as a topology for the high power applications where a function is required to control the zero-sequence component as well as <TEX>$dq$</TEX> components. This paper proposes a carrier-based PWM method for a multilevel four-leg PWM VSI along with introducing a novel offset voltage. The proposed offset voltage makes it possible for the switching sequence of all the legs to be optimized for minimizing the harmonic distortion of the output voltage irrespective of the number of inverter levels. The proposed PWM method based on digital signal processors is implemented and tested by using a prototype three-level four-leg VSI. The feasibility of the proposed PWM method is verified by the spectral analysis, simulation, and experimental results. </P>
PEM Fuel Cell Stack Model Development for Real-Time Simulation Applications
Jee-Hoon Jung,Ahmed, S.,Enjeti, P. IEEE 2011 IEEE transactions on industrial electronics Vol.58 No.9
<P>The increased integration of fuel cells with power electronics, critical loads, and control systems has prompted recent interest in accurate electrical terminal models of the polymer electrolyte membrane fuel cell. Advancement in computing technologies, particularly parallel computation techniques and various real-time simulation tools, has allowed the prototyping of novel apparatus to be investigated in a virtual system under a wide range of realistic conditions repeatedly, safely, and economically. This paper builds upon both advancements and provides a means of optimized model construction boosting the computation speeds for a fuel cell terminal model on a real-time simulator which can be used in a power hardware-in-the-loop application. An elaborate simulation model of the fuel cell stack system has been developed, and a significant improvement in the computation time has been achieved. The effectiveness of the proposed model developed on Opal RT's RT-LAB MATLAB/Simulink-based real-time engineering simulator is verified using the experimental results with a Ballard Nexa fuel cell stack system.</P>
Series Voltage Regulator for a Distribution Transformer to Compensate Voltage Sag/Swell
Kang, Taeyong,Choi, Sewan,Morsy, Ahmed S.,Enjeti, Prasad N. IEEE 2017 IEEE transactions on industrial electronics Vol.64 No.6
<P>This paper presents a series voltage regulator for a distribution transformer which addresses power quality issues in the electrical power distribution system. The proposed system is comprised of a line frequency transformer connected to a power electronic converter which is autoconnected on the secondary side. This autoconnection is facilitated by use of a high-frequency or medium-frequency transformer. A simplified strategy to compensate for voltage sags and swells on the grid side, by providing continuous ac voltage regulation, is discussed. When a voltage sags or swells occur, the power electronic converter generates a compensating voltage, which is vector-added to the grid voltage in order to regulate the output voltage supplied to the load. The proposed system satisfies needs of smart distribution grids in terms of improved availability, equipment protection, and resilience. Detailed analysis is provided with experimental results in order to validate the effectiveness of the proposed system.</P>
Towards a Smart Distribution Transformer for Smart Grid
Taeyong Kang,Somasundaram Essakiappan,Prasad Enjeti,Sewan Choi 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
In this paper, a smart distribution transformer which addresses power quality issues in the electrical power distribution system is presented. The proposed system is comprised of a line frequency transformer connected to a power electronic converter that is ‘auto-connected’ on the secondary side. The auto-connection is facilitated by the use of a high-frequency (HF) / medium frequency (MF) transformer. A simplified strategy to compensate for voltage sags, swells, and distortions on the grid side, by providing continuous ac voltage regulation, is discussed. When a voltage disturbance event occurs, the power electronic converter generates a compensating voltage, which is vector-added to the grid voltage in order to regulate the output voltage supplied to the load. The smart distribution transformer will satisfy the various needs of the present and future distribution smart grid such as improved availability, equipment protection, and resilience. This paper provides detailed analysis, simulation results and experimental results from a scaled down laboratory prototype rated 200 W are also presented to validate the operation of the proposed smart distribution transformer.