• 전기전자학회논문지
• /
• 제17권4호
• /
• pp.537-543
• /
• 2013

본 논문에서는 불연속 주파수 변조 기법을 사용하는 낮은 EMI 분산 스펙트럼 클록 발생기 (SSCG)를 제안한다. 제안된 SSCG는 높은 변조폭을 갖는 삼각 주파수 변조 기법을 사용한다. SSCG의 최대 시간 구간 오차 (MTIE)가 제한 기준을 넘어서면 SSCG의 출력 주파수가 분주기를 거쳐 시간 구간 오차 (TIE)의 값을 감소시킨다. 이러한 불연속 주파수 변조 기법은 주어진 MTIE 제한 기준 내에서 전자기 방사를 효과적으로 감소시킬 수 있다. 이 방법은 일반적인 SSCG보다 전자기 방사를 18.5dB 더 개선하였다.

• Journal of Power Electronics
• /
• 제15권5호
• /
• pp.1207-1216
• /
• 2015

In order to suppress the low frequency oscillation of the neutral-point voltage for three-level inverters, this paper proposes a new discontinuous pulse width modulation (DPWM) control method. The conventional sinusoidal pulse width modulation (SPWM) control has no effect on balancing the neutral-point voltage. Based on the basic control principle of DPWM, the relationship between the reference space voltage vector and the neutral-point current is analyzed. The proposed method suppresses the low frequency oscillation of the neutral-point voltage by keeping the switches of a certain phase no switching in one carrier cycle. So the operating time of the positive and negative small vectors is equal. Comparing with the conventional SPWM control method, the proposed DPWM control method suppresses the low frequency oscillation of the neutral-point voltage, decreases the output waveform harmonics, and increases both the output waveform quality and the system efficiency. An experiment has been realized by a neutral-point clamped (NPC) three-level inverter prototype based on STM32F407-CPLD. The experimental results verify the correctness of the theoretical analysis and the effectiveness of the proposed DPWM method.

• Journal of Power Electronics
• /
• 제18권5호
• /
• pp.1336-1346
• /
• 2018

Wide band gap semiconductor devices such as SiC MOSFETs are becoming the preferred devices for high frequency and high power density converters due to their excellent performances. However, the proportion of the switching loss that accounts for the whole inverter loss is growing along with an increase of the switching frequency. In view of the third quadrant working characteristics of a SiC MOSFET, synchronous rectification discontinuous pulse-width modulation is proposed (SRDPWM) to further reduce system losses. The SRDPWM has been analyzed in detail. Based on a frequency domain mathematical model, a quantitative mathematical analysis of the harmonic characteristic is conducted by double Fourier transform. Meanwhile, a switching loss model and a conduction loss model of inverter for SRDPWM have been built. Simulation and experimental results verify the result of the harmonic analysis of the double Fourier analysis and the accuracy of the loss models. The efficiencies of the SRDPWM and the SVPWM are compared. The result indicates that the SRDPWM has fewer losses and a higher efficiency than the SVPWM under high switching frequency and light load conditions as a result of the reduced number of switching transitions. In addition, the SRDPWM is more suitable for SiC MOSFET converters.

• 전력전자학회논문지
• /
• 제21권6호
• /
• pp.530-537
• /
• 2016

This work deals with a switching method for minimizing overcurrent in a three-phase interleaved bidirectional DC-DC converter with frequency modulation. Generally, a three-phase interleaved DC-DC converter is used to reduce a current ripple component. The combined operation of three-phase and two-phase converters can significantly reduce the ripple component. However, the conventional PWM method cannot solve severe overcurrent during phase transfer or frequency variation for power control. To overcome this problem, this work proposes a new PWM switching method. A 3 kW DC-DC power converter is designed and implemented, and the converter is operated in discontinuous current mode with varying switching frequencies for power control. Simulation and experimental results show the validity of the proposed switching method. The proposed switching method can be widely used in the field of current ripple reduction for three-phase interleaved bidirectional DC-DC converters.

• 한국철도학회논문집
• /
• 제20권4호
• /
• pp.448-457
• /
• 2017

본 논문에서는 불연속 변조 기법을 이용한 고속철도 추진제어장치용 단상 PWM 컨버터에 대해 연구하였다. 기존 PWM 컨버터는 대 전력 특성으로 인해 스위칭 손실을 줄이기 위해 주파수 변조지수를 10 이하로 낮게 사용함에 따라 제어의 대역폭이 감소하고, 안정적인 역률 제어를 위해 추가의 보상 기법을 필요로 하는 등의 문제점을 가지고 있다. 이를 해결하기 위해 3상 PWM 인버터에서 사용하는 불연속 변조 기법을 단상 PWM 컨버터에 적용하였다. 제안한 방식은 옵셋 전압 기법을 활용하여 간단히 구현될 수 있으며 동일 스위칭 손실 대비 주파수 변조 지수를 2배 증가시켜 제어 특성을 향상시키고 스위치 간의 동특성도 동일하게 가져갈 수 있다. 100 kW급 PWM 컨버터에 대한 시뮬레이션을 통해 제안한 불연속 변조 기법에 대한 타당성을 검증하였다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1992년도 하계학술대회 논문집 B
• /
• pp.1142-1146
• /
• 1992

This paper deals with the operation analysis of the half-bridge parallel-resonant converter with P.W.M. control. The converter operates at fixed frequency, in the continuous and discontinuous current mode. A simplified theorectical steady-state analysis is developed and the converter characteristics are presented.

• 조명전기설비학회논문지
• /
• 제22권7호
• /
• pp.28-36
• /
• 2008

This paper presents a novel prototype of zero current switching pulse frequency modulation (ZCS-PFM )high frequency series resonant inverter using IGBT power module for electromagnetic induction eddy current heated roller in copy and printing machines. The operating principle and unique features of this voltage-fed half bridge inverter with two additional soft commutation inductor snubber are presented including the transformer modeling of induction heated rolling drum. This soft switching inverter can achieve stable zero current soft commutation under a discontinuous and continuous resonant load current for a widely specified power regulation processing. The experimental results and computer-aided analysis of this inverter are discussed from a practical point of view.

• 조명전기설비학회논문지
• /
• 제22권7호
• /
• pp.7-15
• /
• 2008

A single active capacitor snubber-assisted soft-switching sinewave pulse modulation utility-interactive power conditioner with a three-winding flyback high frequency transformer link and a bidirectional active power switch in its secondary side has been proposed. With the aid of the switched-capacitor quasi-resonant snubber cell, the high frequency switching devices in the primary side of the proposed DC-to-AC sinewave power inverter can be turned-off with ZVS commutation. In addition to this, the proposed power conditioner in the DCM can effectively take the advantages of ZCS turn-on commutation. Its output port is connected directly to the utility AC power source grid. At the end, the prototype of the proposed HF-UPC is built and tested in experiment. Its power conversion conditioning and processing circuit with a high frequency flyback transformer link is verified and the output sinewave current is qualified in accordance with the power quality guidelines of the utility AC interactive power systems.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
• /
• pp.683-686
• /
• 2001

This paper presents a novel prototype of the utility­interactive voltage source type sinewave pulse modulated power inverter using a high-frequency flyback transformer link. The proposed power conditioner circuit for the solar photovoltaic generation and small scale fuel cell has an isolation function due to the safety of the power processing system, which is more cost effective and acceptable for the small-scale distributed renewal energy conditioning and processing systems. The discontinuous current mode(DCM) of this power processing conversion circuit is applied to implement a simple circuit topology and pulse modulated control scheme. Its operation principle is described on the basis of simulation evaluations and theoretical considerations. The simulation results obtained herein prove that the proposed inverter outputs with sinusoidal waveforms and unity power factor currents are synchronized to the main voltage in utility power source grid. In this paper, the soft switching topology of high­frequency linked sinewave pulse modulation inverter is proposed and discussed.

• 전기학회논문지P
• /
• 제51권3호
• /
• pp.120-125
• /
• 2002

The switching-mode power converter has been widely used because of its features of high efficiency and small weight and size. These features are brought by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI(Electromagnetic Interference) which deteriorate the reliability of the converter themselves and entire electronic systems. This problem on the surge and noise is one of the most serious difficulties in AC-to-DC converter. In the switching-mode power converter, the output voltage is generally controlled by varying the duty ratio of main switch. When a converter operates in steady state, duty ratio of the converter is kept constant. So the power of switching noise is concentrated in specific frequencies. Generally, to reduce the EMI and improve the immunity of converter system, the switching frequency of converter needs to be properly modulated during a rectified line period instead of being kept constant. Random Pulse Width Modulation (RPWM) is performed by adding a random perturbation to switching instant while output-voltage regulation of converter is performed. RPWM method for reducing conducted EMI in single switch three phase discontinuous conduction mode boost converter is presented. The more white noise is injected, the more conducted EMI is reduced. But output-voltage is not sufficiently regulated. This is the reason why carrier frequency selection topology is proposed. In the case of carrier frequency selection, output-voltage of steady state and transient state is fully regulated. A RPWM control method was proposed in order to smooth the switching noise spectrum and reduce it's level. Experimental results are verified by converter operating at 300V/1kW with 5%~30% white noise input. Spectrum analysis is performed on the Phase current and the CM noise voltage. The former is measured with Current Probe and the latter is achieved with LISN, which are connected to the spectrum analyzer respectively.