Analysis of a Hybrid Variable-Frequency-Duty-Cycle-Modulated Low-$Q$ $LLC$ Resonant Converter for Improving the Light-Load Efficiency for a Wide Input Voltage Range

Awasthi, Abhishek; Bagawade, Snehal; Jain, Praveen

doi:10.1109/tpel.2020.3046560

Cited by 36 publications

(8 citation statements)

References 33 publications

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“…Although the proposed control method has a fast reaction speed, the programmer is too complex to finish hard (Li et al, 2020). The reference is lower than the output voltage when the light load condition, the hybrid-adjustable switching-frequency-duty-cycle modulation, is proposed for adjusting the output and improving efficiency (Awasthi et al, 2021). A two-stage voltage modular for LLC converters is discussed by Fei et al (2017), which can reduce the loss of switches, but add extra circuit loss.…”

Section: Introductionmentioning

confidence: 99%

A switching control method based on a new model considering parasitic capacitance for LLC

Han

An³

2023

Front. Energy Res.

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LLC converters are used for linking renewable energy and smart grids. However, the output is higher than the reference caused by its own characteristics, especially in the light load, and the output is limited. A new control method is proposed in this paper based on a new model considering parasitic capacitance, which plays a vital role in keeping the output constant in the light load conditions and widening the output range. In addition, the definition of the light load is given in this paper, which ensures an accurate control. In the switching process, a transition period is set to avoid the components from being damaged due to sudden switching and ensures a smooth output and the stability of the control. Finally, this control method based on the new model is proved valid on a 400 V-36 V-1 kw prototype.

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Section: Introductionmentioning

confidence: 99%

A switching control method based on a new model considering parasitic capacitance for LLC

Han

An³

2023

Front. Energy Res.

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“…However, topologies like [22], [23], [49] are only suitable for low voltage applications. Also, the achievable output voltages by [5], [11], [14]- [17], [24], [50]- [52], which are roughly twice the abovementioned LLC based resonant converters due to their half or full bridge output rectifiers, are still low for lots of applications. On the other hand, although using voltage quadrupler rectifier configuration [2], [6], [20], [53], [54] increases the converter voltage gain and output voltage values, but these values are still low for some applications and we need more improvements.…”

Section: Introductionmentioning

confidence: 99%

A High Step-Up Interleaved Current-Fed Resonant Converter for High-Voltage Applications

et al. 2022

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A current-fed LLC resonant converter is proposed for high-voltage and high-power applications. Here, a two-phase interleaved structure is used in the input stage under the continuous conduction mode (CCM) to effectively reduce the input current and output voltage ripple values and the input filter and the output capacitors volumes. Due to the expandable structure and high voltage gain, the proposed configuration is suitable for high voltage applications since low voltage stresses are applied across its components. In fact, voltage stresses across the power semiconductors, i.e., MOSFETs and output diodes, along with the output capacitors, are almost one-third of the output voltage in the implemented three-stage configuration of the proposed converter. Here, the switching frequency is chosen close to, but less than, the converter series resonant frequency to reduce its different components' current stresses and perform softswitching operation for all power devices under wide input voltage and output power variations. Therefore, conduction and switching losses, and EMI noises are effectively reduced. Consequently, efficiency is improved and high-frequency operation is possible, which reduces the volume of passive components to achieve high-power density. The given topology is thoroughly analyzed mathematically. Also, a 1 kW prototype converter has been implemented to validate the given simulations and analyses. Here, wide input voltage (100 V-200 V) and output power (100 W-1000 W) variations are applied, and an asymmetric pulse width modulation (APWM) technique is used at 143 kHz switching frequency to regulate the output voltage at 1 kV. The obtained maximum efficiency value is 95.3%.INDEX TERMS Asymmetric pulse width modulation (APWM), current-fed converter, interleaved technique, LLC resonant converter, multi-winding transformer.

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“…Other researchers have suggested a feedback control method for wide range regulation. For instance, very light-load regulation can be achieved by phase-shift [21,22] or duty-cycle control [23] of the inverter side legs. From the DCX point of view, they increase system complexity with an extra closedloop control.…”

Section: Introductionmentioning

confidence: 99%

“…Meanwhile, in [22] and [23], they are able to improve light-load regulation using phase-shift and duty-cycle control, which increase their switching losses and consequently, add extra damping to the system. Nevertheless, a hybrid control scheme is also implemented in [23], using an additional frequency modulation (FM) to achieve wide output voltage range. Based on a hysteresis on/off control type, burst mode methods have been also studied [24,25].…”

Section: Introductionmentioning

confidence: 99%

“…In addition, as shown in [21], it is only focused on improving the low‐load efficiency by means of decreasing the transformer losses, rather than improving the output voltage controllability. Meanwhile, in [22] and [23], they are able to improve light‐load regulation using phase‐shift and duty‐cycle control, which increase their switching losses and consequently, add extra damping to the system. Nevertheless, a hybrid control scheme is also implemented in [23], using an additional frequency modulation (FM) to achieve wide output voltage range.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Analysis of light and no‐load operation of a 300 kW resonant single active bridge based on 3.3 kV SiC‐devices

Fortes

Ladoux

Fabre

et al. 2022

IET Power Electronics

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The resonant single active bridge topology (R‐SAB) operated in the half‐cycle discontinuous current mode (HC‐DCM) is a very attractive solution due to its high efficiency, low complexity and fixed voltage transfer ratio (DCX). However, as expected for a series‐resonant converter (SRC), its DCX operation depends on the resonant tank circuit‐parameters, parasitic capacitive elements and output load. Specially, at light and no‐load operation, when the system is extremely underdamped, it may present a large output overvoltage due to resonance interactions. This is of prime importance for converters using medium voltage (MV) SiC‐MOSFETs, which feature significant output capacitances that can lead to voltage breakdown of the rectifier semiconductors. Therefore, the supposed fixed‐voltage transfer ratio is not entirely valid and deserves a proper understanding due its criticality. This paper reviews the subject, clarifying its root cause and its multifactorial dependencies. Moreover, it provides a simple solution based on a variable dead‐time with fixed magnetizing current experimentally verified with a 300kW/1.8kV R‐SAB prototype implemented with MV SiC‐devices.

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Analysis of a Hybrid Variable-Frequency-Duty-Cycle-Modulated Low-$Q$ $LLC$ Resonant Converter for Improving the Light-Load Efficiency for a Wide Input Voltage Range

Cited by 36 publications

References 33 publications

A switching control method based on a new model considering parasitic capacitance for LLC

A switching control method based on a new model considering parasitic capacitance for LLC

A High Step-Up Interleaved Current-Fed Resonant Converter for High-Voltage Applications

Analysis of light and no‐load operation of a 300 kW resonant single active bridge based on 3.3 kV SiC‐devices

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