LLC resonant converter would have light-load voltage regulation problems due to the effect of parasitic capacitances in high frequency range. In this paper, an energy feedback control method is proposed to improve the light-load regulation capacity by using synchronous rectifiers (SRs). The SR bridges are controlled ahead of the primary inverter bridges to deliver the energy from load to source, reducing the output voltage independent of the load. Then the desired voltage can be achieved even in no load conditions by regulating the operation time of the energy feedback mode. The gain, voltage ripple and efficiency performances of the proposed control method are discussed based on the precise analysis and accurate model of the converter. Moreover, the light-load operations of the LLC resonant converter are analyzed deriving the critical load condition. Finally, the proposed control method is verified by the experiments of a 12V/8A LLC resonant converter prototype.

The gain of a LLC resonant converter can vary with the loads that can be used to improve the efficiency and power density for some special applications, where the maximum gain does not apply at the heaviest loads. However, nonlinear gain characteristics can make the converters unstable during a major disturbance. In this paper, the stability of an LLC resonant converter during a major disturbance is studied and a trigger control scheme is proposed to improve the converter’s stability by extending the converter’s operational range. Through in-depth analysis of the gain curve of the LLC resonant converter, we find that the switching frequency range is one of the key factors determining the system’s stability performance. The same result is also obtained from a mathematical point of view by utilizing the mixed potential function method. Then a trigger control method is proposed to make the LLC resonant converter stable even during a major disturbance, which can be used to extend the converter’s operational range. Finally, experimental results are given to verify the analysis and proposed control scheme.

A loosely coupled inductive power transfer (IPT) system for industrial track applications has been researched in this paper. The IPT converter using primary Inductor-Capacitor-Inductor (LCL) network and secondary parallel-compensations is analyzed combined coil design for optimal operating efficiency. Accurate mathematical analytical model and expressions of self-inductance and mutual inductance are proposed to achieve coil parameters. Furthermore, the optimization process is performed combined with the proposed resonant compensations and coil parameters. The results are evaluated and discussed using finite element analysis (FEA). Finally, an experimental prototype is constructed to verify the proposed approach and the experimental results show that the optimization can be better applied to industrial track distributed IPT system.

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.

This paper addresses the issues of coupling and disturbances in a dual-tank water level control system within the context of process control in chemical water treatment at industrial facilities. In response to these challenges, a Layered Composite Decoupling Control system based on the Regional Dynamic Sparrow Search Algorithm (RDSSA-LCDC) is proposed. The utilization of an enhanced Regionally Dynamic Sparrow Search Algorithm (RDSSA) addresses the pitfalls of the Sparrow Search Algorithm (SSA), such as susceptibility to local optima and inadequate precision. RDSSA is employed for the parameter tuning of the system’s PID controller. Structurally, it incorporates a Hierarchical Composite Decoupling Control (LCDC) strategy, initially establishing a forward channel to construct an inner-layer decoupling model employing pre-feedback to rectify the lower-level system’s inputs, thereby mitigating inter-branch coupling. Subsequently, it develops an improved disturbance observer model based on pseudo-inverse compensation in the feedback channel, addressing conventional disturbance observer biases, and observing and suppressing system coupling and disturbances. Finally, within the dual-tank water level control system, various control schemes are simulated and compared, affirming the approach’s commendable decoupling, responsiveness, and disturbance rejection performance.