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In this paper, a frequency-doubling LLC resonant converter with high step-down voltage gain for high input voltage applications is proposed. The three-level structure consisting two series half bridges is adopted in the converter to reduce the voltage stresses of the primary-side switches to only half of the input voltage. Thus the low-voltage rated power devices could be used to improve the converter...
An adaptive secondary-side digital control is proposed for the series resonant converter to solve the loss of ZVS under certain input and load conditions, making it a good candidate for MHz 48V voltage regulators (VRs). By means of varying AC equivalent resistance, the output voltage regulation is achieved by controlling the duty cycle of the synchronous MOSFET. An additional control variable has...
This paper introduces a dual-mode hybrid zero-voltage/zero-current switching (ZVS/ZCS) circuit and a complementary controller for flyback converters operating in discontinuous conduction mode (DCM). The new ZVS/ZCS solution provides soft switching feature and high efficiency throughout the whole operating range. It also requires smaller components than other soft switching solutions [1]–[6]. To achieve...
This paper presents a high efficiency, continuous conduction mode (CCM), zero voltage switching (ZVS) bridgeless AC-DC power-factor-correction (PFC) converter for neighborhood electric vehicle (NEV) battery charging. The converter operates in both pulse-width-modulation (PWM) mode and resonant mode each switching cycle and utilizes standard average-current-mode control. This new modulation technique...
This paper presents a general method to measure the output capacitance (Coss) related energy loss per switching cycle in power MOSFETs used in zero-voltage-switched (ZVS) applications. It is shown that a simple model using Coss in series with a resistance Ross is inadequate for describing the observed energy loss and a different model is needed. This work also shows that the traditional hard-switched...
A new method to selectively control the amount of dc-link voltage ripple by processing the desired reactive power by a DC/DC converter in an isolated AC/DC or AC/DC/AC system is proposed. The concept can reduce the dc-link capacitors used for balancing the input and output power and thereby limiting the voltage ripple. It allows the use of a smaller dc-link capacitor and hence a longer lifetime and...
A traditional Voltage Source Inverter (VSI) has higher efficiency than a Current Voltage Source (CSI) due to the less conduction power loss. However, the reverse recovery of the free-wheeling diode limits the efficiency improvement for the silicon devices based hard-switching VSI. The traditional quasi-soft-switching inverter can alternate between VSI and CSI by using a proper control scheme and thereby...
The emergence of gallium nitride (GaN) based power devices offers the potential to achieve higher efficiencies and higher switching frequencies than possible with aging silicon (Si) power MOSFETs. In this paper, we will evaluate the ability of gallium nitride transistors to improve efficiency and output power density in high frequency resonant and soft-switching applications. To experimentally verify...
A PWM or quasi-square-wave (QSW) zero-voltage-switching (ZVS) non-isolated boost converter using enhancement-mode GaN (eGaN) FETs is reported in this paper. The new converter topology requires small number of passive components, minimizes the converter switching loss under high-voltage high-frequency operations, and offers low-voltage stress across power transistors. A transformer-based floating gate...
This paper proposes a novel high voltage-gain LLC micro-converter for PV applications. The converter has simple structure and minimum components with low cost. It can realize high voltage gain based on the voltage doubler rectifier with the optimal turns ratio. The main power switches can achieve ZVS and the output diodes can realize ZCS in wide input and load range. By utilizing the voltage doubler...
A traditional half-bridge three-phase inverter topology can achieve zero voltage switching by implementing BCM operation which requires no additional power devices or magnetic components. In this paper a variable boundary dualmode current modulation method that combines ZVS and ZCS is proposed in order to improve the efficiency of the BCM current controlled micro-inverter. Decreasing output current...
In this paper, a current-fed asymmetric full-bridge LLCC resonant converter is proposed for the dielectric barrier discharge (DBD) applied to the surface treatment. Compared with a previous design, the asymmetric structure with no front-end buck circuit and only two reverse-voltage blocking diodes is adopted to reduce the component count and circuit complexity. Moreover, the phase-shift control of...
A new low-cost, three-phase, four-switch, three-level, zero-voltage-switching (ZVS), discontinuous-current-mode (DCM), power-factor-correction (PFC) boost rectifier, for short named the three-level TAIPEI rectifier, that achieves a low input-current total-harmonic-distortion (THD) and features ZVS of all the switches is introduced. In the proposed rectifier, the voltage stress of the four switches...
A hybrid phase shifted full bridge (PSFB) and LLC half bridge (HB) dc-dc converter for low-voltage and high-current output applications is proposed in this paper. The PSFB shares its lagging leg with the LLC-HB and their outputs are parallel connected. When the output current is small, the energy of LLC circuit in combination with the energy stored in the leakage inductance of PSFB's transformer can...
The Dual Active Bridge (DAB) converter with the Conventional Phase-shift Modulation (CPM) and Triangular Current Modulation (TCM) are compared in terms of the power transfer and total loss. It is noted that there exists an optimal design trade off among the switching loss, conduction loss and drive loss according to different load current and switching frequency. Therefore, the optimal switching frequency...
A novel phase shift controlled modular DC/DC converter is proposed in this paper by integrating the full-bridge converters and three-level flying-capacitor circuit. Due to the series connection of the full-bridge modules, the high switch voltage stress in the primary side is effectively reduced. Therefore, the low-voltage rated power devices can be employed to obtain the benefits of low conduction...
This paper proposes a single switch soft switching isolated converter. The proposed converter is able to offer low cost and high power density in high step up application due to the following features: ZCS turn on and ZVS turn off of switch and ZCS turn off of diodes regardless of voltage and load variation; simple gate driver circuit and low rated lossless snubeer; reduced transformer volume compared...
A soft-switching full-bridge converter (FBC) with dual-phase-shift control strategy is proposed for high efficiency conversion in wide voltage range applications. The proposed FBC can be operated either in step-up mode or step-down mode. Secondary-side phase-shift control is employed for the step-up mode, while primary-side phase-shift control is adopted for the step-down mode. Zero-voltage-switching...
The small-signal modeling of dual active bridge (DAB) converter dynamics in discrete time is a useful analysis tool due to the ability to incorporate behavior during zero-voltage switching (ZVS) intervals explicitly, and is advantageous for the direct design of digital compensators. While the control-to-output transfer function has been modeled previously, accurate models of the output impedance of...
Motivated by the recent commercialization of gallium-nitride (GaN) switches, an effort was initiated to determine whether it was feasible to switch the flyback converter at 5 MHz in order to improve the power density of this versatile isolated topology. Leakage inductance, harmonic losses in the coupled windings, core loss, layout impedances, gate drivers, and other issues problematic at high frequency...
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