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A new DC converter in DC micro-grid applications is studied and proposed in this paper. The studied converter is based on the series connection of full-bridge resonant circuits to achieve the main advantages of low voltage rating of power devices, wide zero-voltage switching losses on active devices, possible no reverse recovery current loss on rectifier diodes and low current rating on secondary...
UV-lamp driver especially for radiation at 253.7nm plays an important role in sewage treatment. In this paper, characteristics of the excitation of mercury atoms in the lamp are investigated deeply based on both theoretical knowledge on collision and experimental results on relationship between the irradiance at 253.7nm with the lamp power. An optimization design scheme is proposed to prolong the...
The series resonant DC/DC converter with an isolation transformer and bridge mode inverter input junction, at its operation in the Buck case, is investigated, at that input DC supply circuit comprises the qZ (quasi-Z) link as impedance source. Operation at such Buck case can be provided under different inverter bridge control methods. Recommended by the literature sources, is the method of control...
This paper proposes the novel generation method of gate signals to control output voltage in a wide range and to achieve synchronous rectification operating in half-bridge LLC resonant converters. The switching frequency modulation is used in half-bridge LLC resonant converters for control strategy of output voltage. The switching timing of secondary MOSFETs is compensated using the gate signal of...
This paper presents the design and implementation of a Very-High-Frequency (VHF) multi-resonant gate drive circuit. The design procedure is greatly simplified compared with some VHF self-oscillating multi-resonant gate drivers presented in previous works. The proposed circuit has the potential to reduce long start-up time required in a self-oscillating resonant gate drive circuit and to better utilize...
Direct phase or indirect frequency control methods are used in series-resonant bridge power inverters for induction heating to maintain maximum power transfer as the load equivalent electrical parameters change during the heating process. In these applications, to control the power level it is common to use the above resonance operating frequency, where only measurement of the deviation of the phase...
A new vary mode control strategy for LLC resonant converter is proposed, via which the converter circuit works in three different modes selected based on different input voltages, so that under different working conditions, circuit works in a mode that suit the specific condition best, which is conducive to operations in wider input voltage range and to improve operation efficiency amongst the full...
This paper presents a comparison study of three isolated DC/DC circuit topologies, LLC resonant circuit, phase shift bridge circuit and phase shift quasi switched capacitor (QSC) circuit. The device stress of three circuits is compared using total switching device power (SDP) which can be used as an indicator of circuit efficiency, device cooling requirement, device packaging requirement and cost...
The current spike in full-bridge LLC resonant converter during start-up may destroy the circuit. Usually, the frequency modulation is used to solve this problem. However the waveform at the start-up is still not good enough. In this paper, a hybrid modulation method of phase-shift and frequency control is employed for the start-up process of LLC converter. By using the phase-shift modulation, the...
A battery charger applying an inductive power transfer (IPT) for electric vehicles has various advantages. Then, there is a case that the secondary-side converter is connected to the receiving side of the IPT system in order to regulate the charging power for the battery of electric vehicles. In the previous studies about this converter, it was investigated that the type of the secondary-side converter...
The contactless power transfer of dc plug and outlet is proposed in this paper for domestic home appliances dc power system. The medium size dc to dc converter is chosen for transferring 300 V input voltage and generated a 5-level with 600 kHz output voltage by using diode clamped multilevel converter. The output power is set at 300W 48V and the solenoid transformer is functioned as an inductive power...
This paper introduces a robust, hardware efficient, mixed-signal control loop that governs the switching actions of the secondary-side synchronous rectifier (SR) switches of LLC resonant converters. The new SR control method minimizes switching and conduction losses of the SR switches through online optimization of their on-off timing using an auto-tuning process that takes into account the effect...
In order to support different types of rechargeable batteries (e.g. Li-Ion, Lead-Acid, NiMh), the design of universal battery chargers must focus on wide conversion efficiency instead of traditional peak efficiency design. Wide efficiency is the ability to maintain high performance within the nominal output power while supporting the charging cycle voltage of different battery technologies. The objective...
In this paper, a nanosecond level response digital pulse width modulation (PFM) control circuit for the current resonant converter such as LLC has been proposed. The proposed circuit is composed of a unique analog to digital converter and logic based digital controller. With the experimental results, it was confirmed that the switching frequency can be varied from 0.8 to 1.2MHz in regard to 20% variation...
The purpose of this paper is to propose a new control method of wireless power transfer system that can maintain stable power supply even when the positions of the primary and secondary coil or distance between the two coils largely change. The new method will be done by adjusting the switching frequency to a frequency that can obtain the desired output. We confirmed the effectiveness of new wireless...
In this paper, the effect of phase shift modulation on the LLC resonant converter for an interleaved LLC resonant converter with phase shift modulation is investigated. The LLC resonant converters can achieve zero voltage switching (ZVS) of the primary switches and the zero current switching of secondary switches. Due to the sinusoidal shapes and discontinuous conduction of secondary current, the...
This paper proposes a dual-loop voltage control for optocoupler feedback in capacitive output filter converter to mitigate the detrimental effect of the optocoupler on regulation performance. The dual-loop consists of primary-side regulation (PSR) loop and reference voltage correction loop. PSR loop performs output voltage regulation with indirectly sensed output voltage across tertiary winding of...
This paper presents a new switched-capacitor (SC) based partial power architecture which enhances the performance of resonant dc-dc converters operating at high frequency (HF, 3 MHz–30 MHz) and very high frequency (VHF, above 30 MHz). A wider input and output range, larger voltage conversion ratio, smaller size and excellent transient performance are expected. The prototype comprises of a 20MHz resonant...
This paper presents a wireless power transfer system for mobile devices. To achieve high efficiency in the receiver circuit, an optimal switching frequency is required. Through experimental analysis, we suggest the optimal efficiency of a receiver circuit. The switching frequency of this receiver circuit can vary from 500 kHz to 13.56 MHz. The received power has a range of 0 to 5 W, and it has a maximum...
This paper will present the optimization design for medium size converter with high switching frequency for household appliances. The series resonant LLC half-bridge converter, 1 kW, 48V and 600 kHz with coreless transformer has been chosen for the power transferring. System verification has been done by MATLAB/Simulink program, which used to find the optimized parameters and converter output under...
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