• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.8
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• pp.430-435
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• 2006

This paper presents a method about the efficiency analysis and the harmonic reduction of single phase NPC multi-level inverter with LC-trap filter and LCR output filter. The proposed LC-trap filter is comprised of a conventional LC output filter, by using LC-trap filter the need for high damping resistor and low LC cut-off frequency is eliminated. Also, low damping resistor is increased the efficiency of the output filter. Experimental verification of the proposed circuit is provided with single phase NPC multilevel inverter system and DSP controller.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.2
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• pp.117-123
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• 2005

The cutoff frequency of a LC output filter for Dynamic Voltage Restorers (DVR) limits the control bandwidth of a DVR system while it attenuates the inverter switching ripples. For a selected cutoff frequency of a LC output filter, infinite number of L-C combinations is possible. Although different L-C combination has different filter characteristics, the filter design on L-C combination has been depended on field experiences without clear analysis. This paper proposes a design criterion and design examples for the L-C filter combination considering the control characteristics and the size of DVRs. An experimental DVR system based on the proposed LC output filter design methodology is built and tested.

• Journal of Power Electronics
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• v.11 no.1
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• pp.74-81
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• 2011

The cutoff frequency of the output LC filters of PWM inverters limits the control bandwidth of the converter system while it attenuates voltage ripples that are caused by inverter switching activities. For a selected cutoff frequency of an output LC filter, an infinite number of L-C combinations is possible. This paper analyses the characteristics of output LC filters for PWM inverters terms of the L-C combinations. Practical circuit conditions such as no-loads, full resistive-loads, and inductive-load conditions are considered in the analysis. This paper proposes a LC filter design method for PWM inverters considering both the voltage ynamics and he inverter stack size. An experimental PWM inverter system based on the proposed output LC lter design uideline is built and tested.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.5
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• pp.892-897
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• 2007

This paper presents the output filter design and the output characteristic analysis by cut-off frequency set up of the LCR filter on NPC multi-level inverter with trap-filter. The single-phase NPC three-level inverter operates at low switching frequency. The proposed LC trap filter is comprised of a conventional LCR output filter, by using LC trap filter the need for high damping resistor and low LC cut-off frequency is eliminated. Also. low damping resistor is increased the output filter system. The multilevel inverter system used NPC type inverter in proper system for high power application and controller is used DSP(TMS320C31). The effectiveness of proposed system confirmed the validity through SPICE simulation and experimental results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.7
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• pp.347-355
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• 2001

The conventional output filter design methods of a voltage source inverter includes two main problems: the performance is not sure to satisfy the specification under the nonlinear load; the designed filter must be occasionally modified when the controller is designed. In this paper, we analyze the relation between both linear and nonlinear loads, the output voltage magnitude, LC lowpass filter parameters, and the control response time. Upon the basis, both filter and controller are simultaneously designed for the performance to satisfy the specification under the nonlinear load as well as linear load. The proposed method sharply enhances the reliability of the performance. P.U is used for the method to be applied to all the quantities of the system. The simulation and the experiment of the proposed method carried out respectively to verify the validity.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.4
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• pp.313-320
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• 2006

In this paper, a design approach of LC trap filter for output side harmonic reduction of single phase NPC multilevel inverter is proposed, and THD of the output voltage and harmonic FFT of the output current are analyzed. The proposed filter consists of a conventional LCR filter cascaded with an LC trap filter and it is tuned to inverter switching frequency. A NPC multilevel inverter inverter is used an inverter system for high power application and DSP(TMS320C31) is used for the controller. The effectiveness of the proposed system confirmed through simulation and experimental results.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.106-108
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• 2005

High accuracy and stability digital controlled power supply for magnet is developed at PLS. This power supply has three sections. The first section is digital controller including DSP&FPGA and precision ADC, the second section consists of IGBT driver and four quad IGBT switch, and the third section is LC output filter section. AC input voltage of power supply is 3-phase 21V, output current is 0 ${\sim}$ 150 A dc. Switching frequency of four quad IGBT switch is 25 kHz. The output current of power supply has very high accuracy of 100 A step resolution at full range and the stability of +/- 1.5 ppm for short term and +/- 5 ppm for long term. This paper describes characteristics of filter and output current performance improvement after LC output filter at four quad digital power supplies.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.127-132
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• 2000

This paper describes a 3-phase Line-Interactive APF system and analyzes its operating characteristics considering LC Filter output characteristics. Topology of APF is similar to that of Off-Line UPS in the point of parallelly operating inverter system. So it is possible to be multi-functioned active compensating system according to power condition. Likewise this actively operating system from APF to UPS and vice versa is often to be called Line-Interactive system. And more than that Line-Interactive system needs precise design of LC filter on converter output side to make this system fully operate in both APF and UPS modes. The problem in this point is how to design LC Filter to be contented with two different system characteristics so this paper analyzes this problem and proposes its design procedures. Then suggested filter design is verified to be contented by the simulations and experimental results

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.56 no.2
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• pp.83-89
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• 2007

The LC filter design procedure of the inverter output filter is described. The transfer function of the filter output voltage to the load current is described with the capacitor value and the system time constant considering the system controller. By using the closed form of the relation between the filter capacitor value and the system time constant, the capacitor value can be calculated with the given system time constant and vice versa. It is more practical for the implementation of power and control circuit of inverter. And as the effect of the load current to the voltage distortion can be calculated from the closed form, it is possible to analyze the system how much the voltage waveform is distorted in case of the nonlinear load. All the proposed design procedure is verified with the simulation and experimental results.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.118-121
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• 2004

The cutoff frequency of a LC output filter for Dynamic Voltage Restorers (DVR) limits the control bandwidth of a DVR system and the attenuation factor against the inverter switching ripples. For a selected cutoff frequency of a LC output filter, infinite number of L-C combinations is possible. Although different L-C combination has different filter characteristics, the filter design on L-C combination has been depended on field experiences without clear analysis. This paper proposes a design criterion and design examples for the L-C filter combination considering the control characteristics and the size of DVRs. An experimental DVR system based on the proposed LC output filter design methodology is built and tested.