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A new three-phase harmonic-free rectification scheme based on zero-sequence current injection
Choi, Sewan,Won, Chung-Yuen,Kim, Gyu-Sik IEEE 2005 IEEE transactions on industry applications Vol.41 No.2
This paper proposes a new three-phase harmonic-free rectification scheme based on a zero-sequence injection technique. The proposed scheme incorporates two half-bridge inverters and two single-phase transformers to actively and individually shape the positive and negative dc rail currents of the rectifier. The shaped zero-sequence harmonic currents are then circulated through the ac side of the rectifier via a zigzag transformer, resulting in pure sinusoidal input currents in the three-phase diode rectifier. A design example along with component ratings calculation are detailed. Experimental results on a 1.5-kVA prototype are provided to validate the proposed technique.
Sewan Choi,Minsoo Jang Institute of Electrical and Electronics Engineers 2007 IEEE transactions on industrial electronics Vol.54 No.4
<P>This paper presents analysis and control of a hybrid filter that can suppress neutral harmonic currents in three-phase four-wire systems not only with harmonic voltage-source loads but also with harmonic current-source loads. The filter voltampere rating is significantly reduced compared to the conventional neutral-current-suppressing methods. The rectifier part of the neutral harmonic suppressor has been removed by controlling the dc capacitor voltage. The experimental results on a 50-kVA prototype validate the proposed control approach.</P>
Sewan Choi,Minsoo Jang 전력전자학회 2001 ICPE(ISPE)논문집 Vol.2001 No.10
Three-phase four-wire electrical distribution systems are widely employed in manufacturing plants, commercial and residential buildings Due to the nonlinear loads connected to the distribution system, the neutral conductor carries excessive harmonic currents even under balanced loading since the triplen harmonics in phase currents do not cancel each other. This may result in wiring failure of the neutral conductor and overloading of the distribution transformer In response to these concerns, a cost-effective neutral current harmonic suppressor system has been proposed [6].<br/> This paper proposes an improved control method for the harmonic suppressor system under unbalanced load conditions The proposed control method compensates for only the harmonic components in the neutral conductor, and the zero-sequence fundamental component due to unbalanced loading is prevented from flowing through the harmonic suppressor system This remedies overloading and power loss of the system The experimental results on a prototype validate the proposed control approach.
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.
Sewan Choi,Minsoo Jang 전력전자학회 2003 JOURNAL OF POWER ELECTRONICS Vol.3 No.3
Three-phase four-wire electrical distribution systems are widely employed in manufacturing plants, commercial and residential buildings Due to the nonlinear loads connected to the distribution system, the neutral conductor carries excessive harmonic currents even under balanced loading since the triplen harmonics in phase currents do not cancel each other This may result in wiring failure of the neutral conductor and overloading of the distribution transformer In response to these concerns, a cost-effective neutral current harmonic suppressor system has been proposed[6] This paper proposes an improved control method for the harmonic suppressor system under unbalanced load conditions The proposed control method compensates for only the harmonic components in the neutral conductor, and the zero-sequence fundamental component due to unbalanced loading is prevented from flowing through the harmonic suppressor system This remedies overloading and power loss of the system The experimental results on a prototype validate the proposed control approach
Choi, Sewan,Jang, M. IEEE 2004 IEEE transactions on industrial electronics Vol.51 No.4
This letter proposes a reduced-rating hybrid filter to suppress neutral current harmonics in three-phase four-wire systems. Under unbalanced loading, the proposed filter eliminates only harmonics in the neutral current while it does not affect the fundamental. The VA rating of the inverter is significantly reduced compared to the conventional one since only fundamental current due to unbalanced loading could flow through the inverter switch.