• Journal of Power Electronics
• /
• v.15 no.6
• /
• pp.1429-1437
• /
• 2015

A new parallel hybrid soft switching converter with low circulating current losses during the freewheeling state and a low output current ripple is presented in this paper. Two circuit modules are connected in parallel using the interleaved pulse-width modulation scheme to provide more power to the output load and to reduce the output current ripple. Each circuit module includes a three-level converter and a half-bridge converter sharing the same lagging-leg switches. A resonant capacitor is adopted on the primary side of the three-level converter to reduce the circulating current to zero in the freewheeling state. Thus, the high circulating current loss in conventional three-level converters is alleviated. A half-bridge converter is adopted to extend the ZVS range. Therefore, the lagging-leg switches can be turned on under zero voltage switching from light load to full load conditions. The secondary windings of the two converters are connected in series so that the rectified voltage is positive instead of zero during the freewheeling interval. Hence, the output inductance of the three-level converter can be reduced. The circuit configuration, operation principles and circuit characteristics are presented in detail. Experiments based on a 1920W prototype are provided to verify the effectiveness of the proposed converter.

• Journal of Power Electronics
• /
• v.13 no.6
• /
• pp.1058-1069
• /
• 2013

This paper proposes and designs a new output filter called an LCFL filter for application to three phase three wire shunt active power filters (SAPF). This LCFL filter is derived from a traditional LCL filter by replacing its capacitor with a C-type filter, and then constructing an L-C-type Filter-L (LCFL) topology. The LCFL filter can provide better switching ripple attenuation capability than traditional passive damped LCL filters. The LC branch series resonant frequency of the LCFL filter is set at the switching frequency, which can bypass most of the switching harmonic current generated by a SAPF converter. As a result, the power losses in the damping resistor of the LCFL filter can be reduced when compared to traditional passive damped LCL filters. The principle and parameter design of the LCFL filter are presented in this paper, as well as a comparison to traditional passive damped LCL filters. Simulation and experimental results are presented to validate the theoretical analyses and effectiveness of the LCFL filter.

• Proceedings of the KIEE Conference
• /
• 2002.11d
• /
• pp.204-206
• /
• 2002

For small capacity rectifier circuits such as these for consumer electronics and appliances. capacitor input type rectifier circuits are generally used Consequently. various harmonics generated within the power system become a serious Problem. Various studies of this effect have been presented previously. However. most of these employ switching devices, such as FETs and the like. The absence of switching devices makes systems more tolerant to over -load, and brings low radio noise benefits. We propose a power factor correction scheme using a LC resonant in commercial frequency without switching devices. In this method. It makes a sinusoidal wave by widening conduction period using the current resonance in commercial frequency. Hence, the harmonic characteristics can be significantly improved. where the lower order harmonics. such as the fifth and seventh orders are much reduced. The result are confirmed by the theoretical and expermental implementations.

• Journal of the Korean Society of Industry Convergence
• /
• v.23 no.2_1
• /
• pp.115-124
• /
• 2020

In wireless power transfer (WPT) system, the conventional compensation topologies only can provide a constant current (CC) or constant voltage (CV) output under their resonant conditions. It is difficult to meet the CC and CV hybrid charging requirements without any other schemes. In this study, a switching hybrid topology (SHT) is proposed for CC and CV electric vehicle (EV) battery charging. By utilizing an additional capacitor and two AC switches (ACSs), a double-side LCC (DS-LCC) and an inductor and double capacitors-series (LCC-S) topologies are combined. According to the specified CC and CV charging profile, the CC and CV charging modes can be flexibly converted by the two additional ACSs. In addition, zero phase angle (ZPA) also can be achieved in both charging modes. In this method, because the operating frequency is fixed, without using PWM control, and only a small number of devices are added, it has the benefits of low-cost, easy-controllability and high efficiency. A 3.3-kW experimental prototype is configured to verify the proposed switching hybrid charger. The maximum DC efficiencies (at 3.3-kW) of the proposed SHT is 92.58%.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.16 no.4
• /
• pp.22-29
• /
• 2002

Usually, much harmonics are included and cause harmonic loss of motor, torque pulsation, electro-magnetic noise and shock etc. by switching function of inverter when drive induction motor variableness inside. It applied partial resonant Buck converter and three phase voltage type SPWM inverter circuit to induction motor driving system in this paper that see to solve such problem. Changed operation condition variously to do input current of circuit that propose sine-wave by unit power factor almost and capacitor supplied bringing back to life voltage by power supply arranging properly assistance diode and electric power switching. Power factor and efficiency improved as that minimize variation of input at power supply voltage polarity reverse by that add voltage reversal function. Also, by using output filter, reduced harmonic of output line to line voltage components, and introduce state space analysis and forecast operation of rectifier. Such all items confirmed validity through simulation and an experiment.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.19 no.1
• /
• pp.64-70
• /
• 2014

In this paper, the new LLCL filter is proposed for grid connected three-phase PWM inverter for passive damping. LLCL filter inserts a small inductor in the branch of the capacitor of the traditional LCL filter to compose a series resonant circuit to reduce the switching-frequency component on grid current. Using LLCL filter, the switching-frequency current ripple components can be attenuated much better than the LCL filter, leading to a decrease in the total inductance. However, the resonance phenomena caused by zero impedance from the addition of LC branch in LLCL filter can be a big problem. Resonance phenomena of LLCL filter can be a source of grid system instability, so proper damping methods are required. However, it is difficult to apply a passive damping method in the conventional LLCL filter, because the damping resistor increase impedance of the LC branch. Therefore, switching frequency component of grid current can not much attenuated by low Q of LC series resonance effect. In this paper, a new LLCL filter is proposed to overcome the conventional LLCL filter with passive damping. The validity of the proposed method is proven by simulation and experimental result.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.3 no.2
• /
• pp.39-45
• /
• 2010

In this paper, an equally spaced $3{\times}2$ microstrip patch array antenna based on the fundamental infinite wavelength supported by the composite right/left-handed (CRLH) transmission line (TL) is proposed. The proposed CRLH TL unit cell consists of an inter-digit capacitor to realize left-handed (LH) series capacitance and non-symmetric shunt meander line with a shorted via to realize LH shunt inductance. At the infinite wavelength frequency of 2.09 GHz a 6-port series power divider consisting of a 19 unit cells shows a maximum magnitude difference of 0.73 dB and a $0.52^{\circ}$ maximum phase difference between output ports. The measured resonant frequency and maximum gain of the fabricated array antenna is 2.09 GHz and 10.98 dBi, respectively.