To solve the problem of system output voltage fluctuation caused by interferences such as load fluctuation and internal inductor parameter perturbation in a flyback converter, a second-order linear active disturbance rejection control (LADRC) strategy based on output voltage is proposed in this paper. A small-signal model of a CCM flyback converter is established, and the equivalent transfer function of voltage control based on second-order LADRC is derived. A second-order LADRC is constructed, and a parameter design method for the controller is proposed. The response characteristics of the output voltage of the converter under five internal and external disturbances of different control strategies are compared and studied using MATLAB R2022b/Simulink simulation software, and a CCM flyback converter experimental platform based on dSPACE is built to verify the corresponding comparative experiments. The simulation and experimental results jointly verify the superiority of the control strategy for the anti-interference and robustness of the output voltage of the CCM flyback converter.

To address the difficulty of simultaneously achieving fast response, high stability, and strong disturbance rejection in gimbal systems operating under complex conditions, an adaptive control strategy based on offline–online cooperative optimization is proposed. The method is built upon the conventional proportional–integral–derivative (PID) control framework. First, a particle swarm optimization (PSO) algorithm is employed offline to obtain an optimized set of initial control parameters, thereby improving the transient response during the startup phase. Subsequently, a single-neuron adaptive (SNA) mechanism is introduced to adjust the control parameters online according to real-time error information, enhancing the system’s adaptability to environmental variations and external disturbances. Stability analysis demonstrates the convergence of the proposed control scheme. Finally, an experimental gimbal platform is constructed to validate the effectiveness of the method. Experimental results show that, under various disturbance conditions, the proposed strategy effectively reduces angular fluctuation amplitude, shortens the settling time, and maintains smooth control performance. These results indicate that the proposed control strategy exhibits strong robustness and significant engineering applicability.

To address the slow dynamic response of LLC resonant converters under load fluctuations and input voltage jumps in server power supply applications, this paper proposes a novel composite control strategy, namely the model-assisted linear extended state observer based super-twisting sliding mode control (MLESO-STSMC). First, an extended describing function (EDF) method is used to establish a second-order simplified model incorporating the system's beat frequency dynamics to reduce the complexity of controller design. Second, this model information is introduced into the active disturbance rejection control framework to construct the observation loop, i.e., the model-assisted linear extended state observer (MLESO), which alleviates the observer's estimation burden by separating known dynamics and reduces the system's reliance on high observation bandwidth. Meanwhile, the super-twisting sliding mode control (ST-SMC) algorithm is introduced as the feedback loop to replace the linear error feedback control law, which improves the error convergence speed of the system while suppressing the sliding mode chattering phenomenon. Experimental results on a 400V/21V GaN-based half-bridge LLC prototype and the dSPACE control platform show that under load step and input voltage jump conditions, the proposed MLESO-STSMC strategy reduces the overshoot and undershoot amplitudes of the output voltage, achieves a transient settling time of 10ms, and outperforms PI control and linear active disturbance rejection control(LADRC) in dynamic response performance. In addition, under the conditions of a 33.3% reduction in observer bandwidth and system capacitance parameter perturbations, the system can still maintain stable control performance, verifying the parameter robustness and engineering application potential of this strategy.

This paper proposes an output-voltage control method for a half-bridge LLC resonant converter that combines nonsingular fast terminal sliding mode control (NFTSMC) with a linear extended state observer (LESO) to improve dynamic regulation under input-voltage disturbances and load transients. Based on a second-order equivalent model with a lumped disturbance, the LESO provides state and disturbance estimates, while an NFTSMC law replaces the linear state error feedback law in conventional linear active disturbance rejection control (LADRC) to generate the frequency control input with disturbance compensation. Under the assumed disturbance and operating conditions, including boundedness of the lumped disturbance and its derivative and the absence of sustained control-input saturation, theoretical analysis shows bounded observation errors and ultimate convergence of the sliding variable and output-voltage tracking error to small neighborhoods of zero. Simulations of a 240 W system and semi-physical experiments using a dSPACE MicroLabBox and a physical prototype are conducted to compare the proposed method with proportional-integral control and LADRC. In the semi-physical experiments, compared with LADRC, the recovery time and output-voltage fluctuation percentage are reduced by 63.9% and 8.3%, respectively, when the input voltage decreases from 400 to 380 V. When the load current increases from 5.71 to 11.42 A, the corresponding reductions are 29.4% and 20.2%. The results indicate improved dynamic output-voltage regulation and disturbance suppression under the tested operating conditions.

In this study, GaN devices are implemented in low-power three-phase inverters to achieve high-frequency operation and a compact design. A 500 W power-rated prototype operating at a switching frequency of 200 kHz was designed. A linear active disturbance rejection control (LADRC) strategy was introduced to solve the issue of high-frequency inverter oscillation. Additionally, the driving circuit was optimized to address the issue of voltage spikes in the drive voltage. Subsequently, the feasibility and effectiveness of the control strategy were validated through a system simulation model built in Simulink. Lastly, a digital control algorithm was developed by leveraging the capabilities of DSP28034. During testing at an operating frequency of 200 kHz, it was found that the drive voltage waveform was excellent and that the three-phase inverter output remained stable, with no signs of oscillation. The implemented design effectively suppresses peak drive voltage levels, demonstrating optimized gate drive circuitry performance. The output waveform of three-phase inverter proves the effectiveness of the control strategy.

Gallium nitride (GaN) power devices often exhibit output voltage ringing during high-frequency switching due to parasitic parameters. Traditional forward-biased drive schemes not only struggle to effectively suppress this issue but also carry a high risk of false turn-on. Therefore, this study proposes three optimization measures based on the EZDrive architecture: (1) Optimizing passive RC network parameters to reliably generate a negative turn-off voltage at MHz-level frequencies; (2) Matching gate resistors with ferrite beads to synergistically suppress resonance; (3) Addressing variations in gate voltage tolerance across different GaN devices and compatibility with existing controllers by employing a diode clamping network to achieve adjustable clamping threshold gate voltage protection and level adaptation. To validate this approach, an LTspice simulation model was established based on the measured characteristics and datasheet parameters of the Infineon GS61008P enhancement-mode GaN HEMT, and tested at a frequency of 1 MHz. Results demonstrate that compared to traditional approaches, the proposed design actively generates a turn-off negative voltage, effectively suppressing false turn-on. It stably regulates V _gs within the −5 V to +7 V range, aligning with the device’s safe operating area of −10 V to +7 V. Voltage ringing duration decreased from >180 ns to <70 ns (approximately 61% reduction), while rise time shortened from 15 ns to 10 ns (approximately 33.3% improvement). This approach eliminates the need for complex additional active circuits, providing an efficient and practical engineering solution for voltage ringing suppression in high-frequency GaN converters such as automotive chargers and renewable energy inverters.