Because of the different working principles between conventional flyback and active-clamped flyback (ACF), the existing primary-side regulation (PSR) technology cannot be applied to ACF. And in order to achieve PSR of ACF, a low-cost digital sampling method based on the auxiliary winding of the transformer is proposed. In the conventional peak current mode (PCM) controlled ACF, the sampling resistor of primary current may introduce additional power loss, and high-frequency oscillations during sampling may reduce system’s stability. Therefore, a digital feedback-feedforward control (FFC) method is proposed to eliminate the sampling resistor. The stability of the proposed control method and its influence on the dynamic response are studied. In addition, since GaN device has higher power loss during reverse conduction than its Si counterpart, design considerations of reverse conduction time of power switches are also discussed in this paper. All control methods and design considerations are verified on a GaN-based 12V-3A ACF, and the proposed control strategy is implemented by FPGA.

A Novel Digital Control Method of Primary-Side Regulated Flyback With Active Clamping Technique

There has always been a high expectation that wind generation systems would capture maximum power and integrate properly with the grid. Utilizing a wind generation system with increased management to meet the growing electricity demand is a clever way of accomplishing this. However, wind power generation systems require a sophisticated, unique, and dependable control mechanism in order to achieve stability and efficiency. To improve the operation of the wind energy conversion method, researchers are continually addressing the obstacles that presently exist. Therefore, it is necessary to know which control can improve the whole system’s performance and ensure its successful integration into the network, despite the variable conductions. This article examines wind turbine control system techniques and controller trends related to the permanent magnet synchronous generator. It presents an overview of the most popular control strategies that have been used to control the PMSG wind power conversion system. Among others, we mention nonlinear sliding mode, direct power, backstepping and predictive currents control. First, a description of each control is presented, followed by a simulation performed in the Matlab/Simulink environment to evaluate the performance of each control in terms of reference tracking, response time, stability and the quality of the signal delivered to the network under variable wind conditions. Finally, to get a clear idea of the effect of each control, this work was concluded with a comparative study of the four controls.

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A Review on Popular Control Applications in Wind Energy Conversion System Based on Permanent Magnet Generator PMSG

Active clamp flyback (ACF) is a good candidate to be used in high frequency power adapter applications. For high performance, dual-loop dual-variable (DLDV) control strategy consists of voltage, current and period regulation loops is very suitable to be used in ACF converter. However, the complexed control framework makes the controller is hard to design, and which can affect the dynamic response of the system. Therefore, a cascade controller consists of a decoupling controller and digital controller is proposed for good stability and dynamic characteristic. The decoupling controller is used to eliminate the coupling effect between the output voltage and period regulation loop, and the digital controller is adopted to stabilize the system. To verify the effectiveness of the designed controller, simulation and experimental results based on a 65W 19.5V output ACF prototype are tested. By comparing with the non-decoupling controller, the designed controller has a faster dynamic and smaller voltage overshoot and undershoot in DLDV controlled ACF converter.

System Performance Optimization for Dual-Loop Dual-Variable Controlled Active Clamp Flyback Converter Using Decoupling Compensation Technique

Investigation of active-clamped flyback (ACF) dc-dc converter 57W used as the auxiliary power-supply (APS) of an inductive-charging system (ICS) is presented. The ACF was supplied from variable-dc-link 800V which was challenge for its design. Anyway, some findings are applicable to any ACF. An overview of ACF control ICs is presented revealing that only two vendors have appropriate devices for ICS. The key-parts’ choice and suggestion of new features targeting ACF in this emerging-application are given. Striving for high switching-frequency in ICS is not needed due to large safety-distances of transformer. Measured “maximum-efficiency vs. magnetizing-inductance” graph showed that extremes are reached for 400 $\mu \text{H}$ . It was based on four transformers with manually-optimized resonant-tanks. Measurements of “circulating-power losses vs. input-voltage” are compared for several transformers. Those losses are in the range of few watts and increase with input-voltage. Measurements of “bandwidth, phase-margin and gain-margin vs. input-power”, for different input-voltages, are discussed. Those quantities were changeable with load and input-voltage as expected. The short-circuit behavior is analyzed showing that usage of the hybrid-clamp with multi-mode control-ICs is mandatory. Finally, comparison with conventional flyback and quasi-resonant flyback converters showed that both are ≈23% cheaper, occupy ≈11% less board-space, and have similar or higher efficiencies. The reason for such efficiency is that ACF circulating-power losses were high as well as dc-voltage-conversion-ratio. Although this is a drawback, for an APS the efficiency is not the key-parameter as long as there are no thermal problems. Moreover, as ACF converter is known for having less EMI-problems that could be the key-advantage for this application. But problem is not-enough electronic components on the market that are suitable for ICS.

Active-Clamp Flyback Converter as Auxiliary Power-Supply of an 800 V Inductive-Charging System for Electric Vehicles

Investigation of active-clamped flyback (ACF) dc-dc converter 57W used as the auxiliary power-supply (APS) of an inductive-charging system (ICS) is presented. The ACF was supplied from variable-dc-link 800V which was challenge for its design. Anyway, some findings are applicable to any ACF. An overview of ACF control ICs is presented revealing that only two vendors have appropriate devices for ICS. The key-parts’ choice and suggestion of new features targeting ACF in this emerging-application are given. Striving for high switching-frequency in ICS is not needed due to large safety-distances of transformer. Measured “ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">maximum-efficiency vs. magnetizing-inductance</i> ” graph showed that extremes are reached for 400 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{H}$ </tex-math></inline-formula> . It was based on four transformers with manually-optimized resonant-tanks. Measurements of “ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">circulating-power losses vs. input-voltage</i> ” are compared for several transformers. Those losses are in the range of few watts and increase with input-voltage. Measurements of “bandwidth, phase-margin and gain-margin vs. input-power”, for different input-voltages, are discussed. Those quantities were changeable with load and input-voltage as expected. The short-circuit behavior is analyzed showing that usage of the hybrid-clamp with multi-mode control-ICs is mandatory. Finally, comparison with conventional flyback and quasi-resonant flyback converters showed that both are ≈23% cheaper, occupy ≈11% less board-space, and have similar or higher efficiencies. The reason for such efficiency is that ACF circulating-power losses were high as well as dc-voltage-conversion-ratio. Although this is a drawback, for an APS the efficiency is not the key-parameter as long as there are no thermal problems. Moreover, as ACF converter is known for having less EMI-problems that could be the key-advantage for this application. But problem is not-enough electronic components on the market that are suitable for ICS. 

Critical conduction mode (CrCM) active clamp flyback (ACF) converter is regarded as a good candidate for low power adaptor applications. However, the most adopted control strategy of variable-frequency peak current mode (VF-PCM) and discrete zero voltage switch (ZVS) control makes it difficult to get the accurate small signal model. Therefore, by using sampled-data modeling method, this paper proposes an exact small signal model of CrCM ACF converter for the first time. In the modeling process, the influence of discrete-ZVS control is firstly considered. The conduction time of power switch is regarded as the control signal, which is different from constant-frequency converter. The total current close-loop transfer function is simplified by the linear combination of single VF-PCM and discrete-ZVS control model. After considering the sampling effect and the modulator gain from the derived sampled-data model respectively, the control-to-output transfer function of CrCM ACF converter is developed. The analytical results are analyzed by comparing with single VF-PCM and the widely used average model. Finally, to validate the accuracy of the proposed model, a 65W 20V output CrCM ACF converter is simulated and measured. The verification shown that the proposed sampled-data model is basically agreement with the simulation and experimental results.

Sampled-Data Modeling for PCM and ZVS Controlled Critical Conduction Mode (CrCM) Active Clamp Flyback (ACF) Converter at Variable Switching Frequency

Aiming at the problem of low tracking accuracy of the manipulator in the presence of model parameter errors and external disturbance, this paper proposes an adaptive fractional-order non-singular fast terminal sliding mode (AFONFTSM) controller based on a fixed-time disturbance observer (FTDO). The controller is split into three portions. First, a fractional-order non-singular fast terminal sliding mode (FONFTSM) surface is designed to improve the tracking accuracy and convergence speed of the error state. Second, to enhance the performance of the system state in the approaching mode, an adaptive variable exponential power reaching law (AVEPRL) is designed, which changes the coefficient of the exponential term through the size of the system state. Meanwhile, adaptive control is used to modulate one item of the reaching law, which improves the anti-interference of the system. In the end, the real-time estimation of the external disturbance is carried out by the FTDO, which solves the problem that the magnitude of the external disturbance is difficult to be determined in the actual engineering. And the stability is verified by the Lyapunov theory. The simulation results display that the controller raised in this paper has better tracking precision, faster convergence speed, and stronger robustness.

Adaptive Fractional-order Non-singular Fast Terminal Sliding Mode Control Based on Fixed Time Observer

This paper studies the issue of high-precision trajectory tracking control for manipulator systems with uncertainty disturbances and develops a fast fixed-time control scheme. First, a new type of (FTSM) surface is constructed by combining inverse trigonometric functions, regardless of the size of the system state, which can obtain a faster convergence velocity and high accuracy. The stabilization time of this sliding mode (SM) surface is independent of the initial state. Subsequently, on this basis, an adaptive fixed-time control method is constructed by combining adaptive techniques through the new fixed-time stability lemma proposed in this paper, under which the system's SM variables and tracking errors are guaranteed to reach the region near the equilibrium point at a fixed time while the adaptive law estimates the upper bound of the disturbance and effectively weakens the chattering phenomenon. Finally, the simulation comparison is carried out under different conditions, and the simulation results show the superiority of the control scheme with high precision, fast velocity, and good robustness. 

Novel fast fixed-time sliding mode trajectory tracking control for manipulator

Adaptive faster fixed-time trajectory tracking control for manipulator

The invention relates to a self-adaptive synchronous rectification control system and method for an LLC resonant converter, and the system comprises: a sampling circuit which has an input end connected with the drain electrode of a synchronous rectification tube and is used for collecting the drain electrode voltage of the synchronous rectification tube; a comparator, wherein the input end of thecomparator is connected with the output end of the sampling circuit, and the comparator is used for comparing the input drain voltage with a preset voltage threshold value and outputting a comparisonresult; and a control unit whch is connected with the comparator and the grid electrode of the synchronous rectifier tube and is used for controlling the conduction duration of the synchronous rectifier tube in one working period. According to the invention, the voltage of the drain end of the synchronous rectifier tube can be directly judged, so that whether the synchronous rectifier tube is in an optimal turn-off state or not is obtained, and turn-off control is carried out on the synchronous rectifier tube according to the optimal turn-off state, and the synchronous rectifier tube is adjusted to a proper turn-off point. According to the method, a self-adaptive synchronous rectification algorithm is adopted, and self-adaptive control over the conduction time of a synchronous rectification tube can be achieved according to the change trend of the switching frequency of a primary side switching tube.

Ran Shi

Papers

Sampled-Data Modeling for PCM and ZVS Controlled Critical Conduction Mode (CrCM) Active Clamp Flyback (ACF) Converter at Variable Switching Frequency

Adaptive Fractional-order Non-singular Fast Terminal Sliding Mode Control Based on Fixed Time Observer

Novel fast fixed-time sliding mode trajectory tracking control for manipulator

Adaptive faster fixed-time trajectory tracking control for manipulator

Self-adaptive synchronous rectification control system and method of LLC resonant converter