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A control algorithm for an integrated power factor correction (PFC) and series resonant converter (SRC) using only two switches is presented, allowing to open loop control the AC input current and the DC output current independently. The theory for this approach is analyzed in time domain and a novel approach for open loop regulation is presented and verified. The software defined power (SDF) control...
This paper analyzes the design and construction of a SiC-based Dual Active Bridge (DAB) converter for its use in a three-stage Power Electronic Transformer (PET) based on a Modular Multilevel Converter (MMC). The galvanic isolation between primary and secondary of the PET provided by the DAB High Frequency Transformer (HFT) is 24 kV. Challenges for the HFT design are discussed. A 5 kW DAB prototype...
A dual active bridge (DAB) dc-dc converter has a limited soft-switching range and high circulating current with the conventional phase shift modulation (PSM) when a voltage variation occurs in the input/output voltage. To overcome these issues, single pulse-width modulation (SPWM) and dual pulse-width modulation (DPWM) were proposed and combined into one modulation strategy called combined pulse-width...
The AC/AC single-phase/single-phase Modular Multilevel Converter (MMC) presents very interesting features for the realization of a Medium Frequency Power Electronic Transformer for traction applications, in AC-fed or multisystem railway rolling stock, like locomotives, Electric Multiple Units (EMU), high-speed units, and so on. Aiming to maximize the output frequency of the converter, i.e. the operating...
The paper presents a single stage soft-switching tri-port converter for integrating renewable sources like PV, and battery storage with grid through high-frequency isolation. The proposed tri-port converter can be easily configured to connect to single or three-phase ac grids and is capable of realizing soft-switching across the entire range of operating load levels. The single stage approach reduces...
This paper presents a design and construction of an integrated magnetic element IME to achieve high efficiency and high power density in 1250 W LLC resonant converter. Superposition of two magnetic inductions oriented antiparallelly in the chosen areas of IME allows reduction of the volume required for inductive elements, increased coefficient of transferred power to volume [W/dm3] and reduction of...
Current Solar Electric Vehicles have flat roofs, in an attempt to reduce irradiance mismatches within the strings of PV cells. As a result the aerodynamic performance and design freedom of such vehicles are limited. This paper presents a distributed maximum power point tracking methodology specifically aimed at Solar Electric Vehicles to overcome this problem. As a starting point, the PV-to-isolated...
A novel configuration of the dual active bridge (DAB) DC/DC converter is presented, enabling more efficient wide voltage range conversion at light loads. A third phase leg as well as a center-tapped transformer are introduced to one side of the converter. This concept provides two different turn ratios, thus extending the zero voltage switching operation resulting in higher efficiency. A laboratory...
Focus is on the design and development of an auxiliary power supply converter for HVDC and FACTS applications, utilising integrated gate-commutated thyristors. Due to relatively high requirements for gate drive power and operating voltage of 2.8 kV, special measures have to be considered when designing such systems. The tapped-inductor buck converter topology was chosen as the first non-isolated conversion...
A circuit topology and its control for a bi-directional isolated series resonant converter (SRC) are proposed. In general SRCs, when the output voltage is decreased, the turn-off current and the switching frequency are increased and efficiency is decreased due to the increase of switching loss. MOSFETs are therefore mainly used, as MOSFETs have a lower turn-off loss than IGBTs. In the present study,...
The traditional phase shift modulation for the dual active bridge DC/DC-converter has the disadvantage of losing zero voltage switching (ZVS) at low load operations. This paper proposes a novel modulation scheme which enables the use of ZVS at low load conditions with a constant starting current and other advantages such as completely linear behavior at low loads and higher robustness against parameter...
Coss nonlinear behavior of modern power FETs challenges large-signal model development used for DC-DC converter efficiency optimization. Small-signal data available in vendor's specifications could mislead and cause errors. Paper reviews existing modeling approaches and suggests accurate practical large signal Coss models for popular wide bandgap (WBG) FETs based on experimental test setup.
Resonant converters find widespread application in the industries for Radio Frequency (RF) heating. Various topologies using vacuum tubes are currently used for such application. Realizing class D topologies with solid state devices could provide more reliability. This work explores possibility of developing a 1kW Class D resonant converter for heating applications using Si/SiC MOSFETs which can replace...
The loss contribution of a 2.3 kW synchronous GaN-HEMT boost converter for an input voltage of 250 V and an output voltage of 500 V was analyzed. A simulation model which consists of two parts is introduced. First, a physics-based model is used to determine the switching losses. Then, a system simulation is applied to calculate the losses of the specific elements. This approach allows a fast and accurate...
This paper analyzes a three-phase Dual Active Bridge (DAB) dc-dc converter with three-level phase-legs, showing a significant increase in the soft-switching region compared to two-level operation. A strategy is presented that results in a Zero Voltage Switching (ZVS) modulation scheme that relies on analytical equations, uses a small amount of switching modes, and obtains close-to-minimal rms currents.
In this work a demonstrator with a switching frequency up to 2.5 MHz is shown. These comparatively high frequencies reduce the weight and the system costs of the resonant 3-kW-DC-DC-converter. The electrical properties of the implemented Gallium Nitride (GaN) power transistors enable high switching frequencies while maintaining high efficiency. The presented converter has a power density of approximately...
A three-phase dual active bridge (DAB) converter with three-level phase-legs is analyzed, showing an increased soft-switching region and a reduction in rms current in the ac-link for unequal input and output voltages compared to the conventional two-level circuit. Furthermore, a comparison of the semiconductor losses is carried out for different three-level inverter implementations using commercially...
This paper presents a novel control concept for the bidirectional non-inverting buck-boost converter to achieve extreme high-efficiency power conversion. The duty cycle, duty ratios and time delays of the PWM control signals for the switches are modulated depending on operating points to minimize the power losses in the converter. A 3kW prototype of the converter using SiC MOSFETs has been designed...
Resonant converters represent a suitable family of topologies that can handle the loose inductive coupling encountered in applications for contactless energy transfer while still providing high efficient operation. However, the analysis of resonant converters is in general cumbersome. On circuit level, a design procedure based on the extended first harmonic approximation of the multi-resonant LLCC...
This paper presents the concept of a high-power DC/DC class of converters with a Q-factor limiter based on a serial LLC type resonant circuit. The Q-factor limiter allows highly accurate determination of the voltage/current limit values in the resonant circuit's passive elements thus significantly increasing immunity to transient states. Properties of the proposed topology are confirmed by the results...
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