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The instantaneous output power of the two-stage single inverter pulsates at twice the output voltage frequency, generating second harmonic current (SHC) in the input dc voltage source and the front-end dc-dc converter. To eliminate the SHC, a second harmonic current compensator (SHCC), whose input current is controlled by the improved one-cycle-control (OCC) proposed in this paper, is applied to compensate...
To achieve high power-density isolated dc-dc converter, gallium nitride high electron mobility transistors (GaN-HEMTs) and planar transformer have been used. Also, for the high power-density design, these components are placed close to each other. GaN-HEMTs are significantly affected by the leakage flux of the planar transformer, because of their lateral structure. Therefore, the mutual effects of...
One of the main challenges of a Solid-State transformer (SST) lies in the dc-dc conversion stage. In this work, a Quadruple-Active-Bridge (QAB) dc-dc converter is investigated to be used as the basic module for the whole dc-dc stage. Besides the feature of high power density and soft-switching operation, the QAB converter provides a solution with a reduced number of high frequency transformers, since...
This paper introduces a new single-switch nonisolated dc-dc converter with very high voltage transfer ratio and reduced semiconductor voltage stress. The converter utilizes an integrated autotransformer and a coupled inductor on the same core to achieve a high step-up voltage gain without extreme duty cycle. Further, an integrated passive regenerative circuit recycles the leakage energy of the coupled...
This paper clarifies the relationship between the current ripple and the power density in bidirectional DC-DC converters. In the conventional power density design method, in order to obtain the pareto-front curve of the power density and the efficiency, the current ripple is designed as constant value, whereas the switching frequency is varied. As a result, the possibilities of higher power density...
This paper presents a DC-DC power converter control scheme and system architecture for batteries which are connected in parallel in order to maintain State-Of-Charge (SOC) balancing between batteries without the need for additional circuitries and their associated controllers. When the battery cells or battery packs are connected in parallel, it is desired to maintain SOC balancing during both charging...
A novel power decoupling circuit using a flying capacitor topology is proposed in this paper. The inverters, which are connected to a single-phase grid, have single-phase power fluctuation at the twice the grid frequency. Thus, bulky electrolytic capacitor is generally used as DC link capacitor. In the proposed circuit, the power fluctuation is compensated by the flying capacitor in the flying capacitor...
With a stringent input-to-output conversion ratio (CR) of 20 (24V input and 1.2V output) for a DC-DC converter, two stage cascaded architectures are easy to implement, but suffer from poor efficiency and doubled number of power components. This paper presents a single-stage solution with a proposed Adaptive ON-OFF Time (AO2T) control. In steady state, the control works as an adaptive ON-time valley...
Concerning cost, volume, and efficiency, Adjustable Speed Drive (ASD) systems are commonly employed with diode rectifiers or Silicon Controlled Rectifiers (SCR) as the front-ends (i.e., ac-dc converters). Apart from low cost, small volume, and high reliability, harmonic currents are significantly produced at the grid side by the rectification apparatus (i.e., diode rectifiers or SCR). As a simple...
Pulse skipping modulation (PSM) helps to improve the light-load efficiency in a DC-DC converter with a stable periodic behaviour and predictable ripple parameters. A periodic steady-state operation under PSM consists of a charge pulse followed by a pre-defined count of skipped pulses, where individual pulses are referred to a fixed-frequency clock with a time period T. Thus the overall time period...
Inductor-less, high gain DC-DC converter with high efficiency and high power density is a much desired circuit in Electric Vehicle (EV) powertrain and Solar photovoltaic (SPV) power converters. Modular Multi-level capacitor clamped DC-DC converter circuits (MLCCC) provide a viable solution for this case. But, their application is limited owing to their limitations in terms of fixed output voltage...
This paper introduces a hybrid step-down dc-dc converter, targeted for battery powered portable applications where low-volume implementation is the key priority. The introduced architecture, combining switched-capacitor (SC) and inductor based circuits, requires low-volume for implementation by reducing the size of the filer inductor by 4 times and the output capacitor by 2 times. In addition to supporting...
The Dual Active Bridge (DAB) DC-DC converter is one of the most popular circuits for bi-directional applications because of simple structure. However, DAB DC-DC converter has few problems such as the surge voltage and hard switching in specific conditions. These problems are caused by the relationship between the output power and phase difference, which causes device breakdown and deterioration of...
This paper proposes a method to achieve maximum power point tracking (MPPT) function by “tricking” inexpensive commercial-off-the-shelf (COTS) current mode control regulators. In the commercial market, there are many such inexpensive regulators, but they are designed for the output voltage control. The proposed method utilizes a voltage signal from an additional external microcontroller to regulate...
One of the undesirable power quality phenomenon in the distribution systems is voltage sag which risks the operation of sensitive loads. Dynamic voltage restorer (DVR) is well-known and reliable solution to mitigate this phenomenon and protect the sensitive loads. This paper proposes new configuration of DVR for medium-voltage applications. The proposed configuration contains diode rectifier to converter...
A quasi-Z-source modular cascaded converter (qZS-MCC) is proposed for high-voltage (HV) dc integration of photovoltaic (PV) power. The qZS-MCC comprises front-end isolated qZS half-bridge (HB) dc-dc converter submodules (SMs) in series. By the qZS-HB handling PV voltage and power variations, a unified duty cycle is applicable for the front-end isolation converter of all SMs. Resultantly, the proposed...
This paper presents a new bidirectional multilevel modular switched-capacitor dc-dc converter for high voltage and high conversion ratio application with low capacitor voltage rating. For the high voltage and high conversion ratio application, high voltage capacitor with good performance will not be available either, like the switching devices. For the traditional multilevel modular switched-capacitor...
A new integrated transformer with variable turns ratio is proposed to enable dc-dc converters operating over a wide input voltage range. The integrated transformer employs a new geometry of magnetic core with “four legs”, two primary windings with orthogonal arrangement, and “8” shape connection of diagonal secondary windings, in order to make the transformer turns ratio adjustable by controlling...
This paper proposes a new symmetrical bidirectional L3C resonant converter with wide voltage range. Due to the proposed symmetrical resonant tank with notch resonant characteristic, the proposed converter is capable of not only achieving soft switching of all switches in forward and backward modes but also operating in a narrow switching frequency range even under wide voltage range. Also, due to...
The paper presents the design and development of an ultra-high efficiency bidirectional isolated full bridge dc-dc converter using Gallium Nitride (GaN) devices. To achieve ultrahigh efficiency, GaN devices, synchronous rectification and high efficiency magnetics are used. The proposed bidirectional converter allows a power flow in both directions using the same power components; this increases power...
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