This article investigates the influence of external disturbances and load switching on the quality of power supply voltage when employing parallel-type active power filters (APF). The study is driven by the increasing requirements of modern precision electronic equipment for power sources with extremely high stability and low ripple levels, typically ranging from 0.001% to 0.01% of the nominal value. The core objective of the research is to assess the dynamic accuracy and stability of APF output parameters under various operational conditions to guarantee the functionality of high-precision systems.
The methodology utilizes imitation modeling within the MATLAB/Simulink environment to analyze the system's reaction to abrupt changes in input signals, specifically employing a "unit step function" to evaluate transient responses. The research established a significant correlation where the amplitude and duration of transient processes are directly determined by the system's loop gain coefficient. Findings indicate that during startup, amplitude surges can exceed the input signal by up to twofold, with post-transient low-frequency oscillations lasting up to 1 second at amplitudes reaching 5V.
The analysis further examines the inclusion of an uncontrolled rectifier, which was found to accelerate the startup process to within 150 ms, although oscillations at the passive filter's natural frequency remain present. Crucially, the study reveals that adjustments to passive filter components, such as inductance (L1) and capacitance (C2), do not substantially change the transient characteristics or surge magnitudes, highlighting the active component's primary role in forming system dynamics.
Additionally, the system's response to load switching was analyzed, revealing decaying oscillatory processes where the initial voltage deviation is proportional to the magnitude of the switched load. To optimize performance and reduce these surges, a combined control strategy involving PID regulators and Pulse Width Modulation (PWM) was implemented. This approach proves effective in compensating for dynamic disturbances and maintaining high-precision voltage stabilization. The results confirm that optimized parallel active filters are vital for meeting the stringent power quality requirements of high-precision electronic power supplies.
