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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.
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.
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/>
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>
A Ripple Current Reduction Method with Fast Dynamic Response for Fuel Cell Application
G. B. Joung,H. J. Yun,PRASAD N. ENJETI 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
A new ripple current reduction method of fuel cell output for boost converter, which has no additional active filter, is proposed. In proposed method, the converter controls the ripple current as well as output voltage of the converter. A current ripple reduction pass of the control loop, which has little affection of controller, has added for fast output voltage dynamics. The dynamics of the output voltage designed very fast with only about 16 ms, which is as low as two periods of 120 Hz current ripple of inverter load. The above<br/> characteristics are verified by PSIM simulation.
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>
Chunyang Gu,Harish S. Krishnamoorthy,Prasad N. Enjeti,Zedong Zheng,Yongdong Li 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6
A new type of topology with medium-frequency-transformer (MFT) isolation for medium voltage wind power generation systems is proposed in this paper. This type of converter is a high density power conversion system, with high performance features suitable for next generation wind power systems in either on-shore or off-shore applications. The proposed topology employs single-phase cascaded multi-level AC-AC converters on the grid side and three phase matrix converters on the generator side, which are interfaced by medium frequency transformers. This avoids DC-Link electrolytic capacitors and/or resonant L-C components in the power flow path thereby improving the power density and system reliability. Several configurations are given to fit different applications. The modulation and control strategy has been detailed. As two important part of the whole system, a novel single phase AC-AC converter topology with its reliable six-step switching technique and a novel symmetrical 11-segment modulation strategy for two stage matrix converter (TSMC) is proposed at the special situation of medium frequency chopping. The validity of the proposed concept has been verified by simulation results and experiment waveforms from a scaled down laboratory prototype.
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>
Gu, Chunyang,Krishnamoorthy, Harish S.,Enjeti, Prasad N.,Zheng, Zedong,Li, Yongdong The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6
A new type of topology with medium-frequency-transformer (MFT) isolation for medium voltage wind power generation systems is proposed in this paper. This type of converter is a high density power conversion system, with high performance features suitable for next generation wind power systems in either on-shore or off-shore applications. The proposed topology employs single-phase cascaded multi-level AC-AC converters on the grid side and three phase matrix converters on the generator side, which are interfaced by medium frequency transformers. This avoids DC-Link electrolytic capacitors and/or resonant L-C components in the power flow path thereby improving the power density and system reliability. Several configurations are given to fit different applications. The modulation and control strategy has been detailed. As two important part of the whole system, a novel single phase AC-AC converter topology with its reliable six-step switching technique and a novel symmetrical 11-segment modulation strategy for two stage matrix converter (TSMC) is proposed at the special situation of medium frequency chopping. The validity of the proposed concept has been verified by simulation results and experiment waveforms from a scaled down laboratory prototype.