Abstract:Output voltage low-frequency oscillation phenomenon in pulse skipping modulation (PSM) buck converter in continuous conduction mode (CCM) and its forming mechanism is revealed and analyzed, and a technique to restrain this phenomenon is proposed by applying inductor current ripple injection feedback (ICRIF) method. The results indicate that the output capacitor equivalent series resistance (ESR) is a key parameter to affect the control performance of PSM CCM buck converter. When smaller ESR output capacitor is used, the output voltage low-frequency oscillation is triggered; while when larger ESR output capacitor is used, this phenomenon can be suppressed, but the output voltage ripple is still large. By utilizing the ICRIF method, the low-frequency oscillation phenomenon at low ESR output capacitor can be suppressed and the output voltage ripple can be reduced effectively. The circuit experimental results verify the correctness of theoretical analysis and circuit simulation.
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