Optimal Design of a High Efficiency LLC Resonant Converter with a Narrow Frequency Range for Voltage Regulation

Abstract

As a key factor in the design of a voltage-adjustable LLC resonant converter, frequency regulation range is very important to the optimization of magnetic components and efficiency improvement. This paper presents a novel optimal design method for LLC resonant converters, which can narrow the frequency variation range and ensure high efficiency under the premise of a required gain achievement. A simplified gain model was utilized to simplify the calculation and the expected efficiency was initially set as 96.5%. The restricted area of parameter optimization design can be obtained by taking the intersection of the gain requirement, the efficiency requirement, and three restrictions of ZVS (Zero Voltage Switch). The proposed method was verified by simulation and experiments of a 150 W prototype. The results show that the proposed method can achieve ZVS from full-load to no-load conditions and can reach 1.6 times the normalized voltage gain in the frequency variation range of 18 kHz with a peak efficiency of up to 96.3%. Moreover, the expected efficiency is adjustable, which means a converter with a higher efficiency can be designed. The proposed method can also be used for the design of large-power LLC resonant converters to obtain a wide output voltage range and higher efficiency.

Optimal Design of Multi-Output LLC Resonant Converter with Independently Regulated Synchronous Single-Switched Power-Regulator

“…In contrast, the resonant current i pri(t) decreases more when M 3 is turned on later. The output voltage Vo1 can be controlled by determining the switching frequencies of M1 and M2, as in a conventional LLC resonant converter [15][16][17][18]. However, io2 is controlled by the turn-on point of M3 when M2 is turned on.…”

Speed and Pressure Controls of Pumps-as-Turbines Installed in Branch of Water-Distribution Network Subjected to Highly Variable Flow Rates

“…Moreover, it reports the amount of energy that could not be recovered by the PaTs for the operational constraints and that was dissipated by the PRV; finally, the same table shows the percentage of recovered energy in each case with respect to the wasted energy in the PRVs. Economic savings were evaluated considering an electricity price of 0.22 €/kWh [40] and efficiency of frequency converters equal to 96% [41].…”

Circuit Topology and Small Signal Modeling of Variable Duty Cycle Controlled Three-Level LLC Converter

“…In small signal modeling, the modulation frequency is lower than the switching frequency and thus can be considered to operate in steady state condition. Substituting the Equations (10)- (12) in 3and equating the coefficients of dc, sine and cosine terms the following harmonic balance is established…”

“…From the DC link voltage supplied by the Power Factor Corrector (PFC), the DC-DC converter charges the battery through the transformer [7,8]. LLC converters have been a widespread choice for the DC-DC converter stage in EV chargers [9][10][11][12]. This type of converter is capable of achieving Zero Voltage Switching (ZVS) at the switches and Zero Current Switching (ZCS) at the rectifier diodes at almost all load conditions.…”