Rectifier Current Control for an LLC Resonant Converter Based on a Simplified Linearized Model

Abstract

In this paper, a rectifier current control for an LLC resonant converter is proposed, based on a simplified, two-order, linearized model that adds a rectifier current feedback inner loop to improve dynamic performance. Compared to the traditional large-signal model with seven resonant states, this paper utilizes a rectifier current state to represent the characteristics of the resonant states, simplifying the LLC resonant model from seven orders to two orders. Then, the rectifier current feedback inner loop is proposed to increase the control system damping, improving dynamic performance. The modeling and design methodology for the LLC resonant converter are also presented in this paper. A frequency analysis is conducted to verify the accuracy of the simplified model. Finally, a 200 W LLC resonant converter prototype is built to verify the effectiveness of the proposed control strategy. Compared to a traditional single-loop controller, the settling time and voltage droop were reduced from 10.8 ms to 8.6 ms and from 6.8 V to 4.8 V, respectively, using the proposed control strategy.

Research on Digital Synchronous Rectification for a High-Efficiency DC-DC Converter in an Auxiliary Power Supply System of Magnetic Levitation

“…Energies 2020, 13, x; doi: FOR PEER REVIEW www.mdpi.com/journal/energies Figure 10 shows the control block diagram of the phase width modulation (PhWM) strategy. In respect to the traditional control method, the switching frequency is the control parameter according to the main circuit parameters [28]. However, the PhWM strategy used in the H-bridge DC-DC converter also applies to the LLC DC-DC converter.…”

“…Moreover, there are few studies on the DSR strategy in high-power applications. Therefore, it is necessary to further study the DSR strategy for the LLC DC-DC converter [26][27][28][29][30][31][32][33].…”

Flux-Balance Control for LLC Resonant Converters with Center-Tapped Transformers

“…Therefore, it is difficult to obtain its small-signal model through mathematical derivation. Previously, researchers had developed the mathematical methods for deriving the small-signal dynamic model of the LLC resonant converter [16][17][18][19]. However, these works focused only on the matching with circuit ac sweep simulation occurs only under specific operating conditions.…”

“…Moreover, for small-signal model, the mathematical methods for deriving the small-signal dynamic model of the LLC resonant converter were developed [16][17][18][19]. However, these works focused only on the switching frequency to output voltage transfer function.…”

Control of an Inductive Power Transfer System Using a Double Coil Structure

“…The large and small-signal models were derived from a T model of a simplified IPT system circuit, using harmonic approximation and fundamental harmonic analysis (FHA). The principle is similar to the control design of resonant power converters, such as LLC converters [8,9]. The development of a single-coil model was also proposed in [10][11][12][13][14] using the same methods.…”