Small-signal analysis of the Buck circuit with active ripple compensation for LED
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Abstract:
Considering that the lifespan of electrolytic capacitor in power supply doesn’t match the LED’s, the authors propose a Buck converter which employs active ripple compensation circuit to drive LED. The circuit structure and working principle of the new topology is introduced and an equivalent small-signal model is established. The formula of output current and the transfer functions of output current with input voltage and duty cycle are obtained through the small-signal model. According to the magnitude and phase Bode plot of the transfer functions’ first-order factor, the input disturbance can be completely filtered, and the output current is a DC theoretically, provided the appropriate parameters are selected. Finally, the correctness of the new topology and its small-signal model are confirmed by carrying out the simulations and experiments.
