In this applet a buck (step-down) converter is used to investigate the influence that the input voltage, load current, switching frequency and duty cycle has on the inductor current ripple. For this circuit both the inductor and capacitor of the output filter are fixed values.
The amplitude of the current ripple is dependent only on the voltage waveform applied across the inductor. Therefore the current ripple amplitude is dependent on the input voltage level, the duty cycle and switching frequency. If the duty cycle is either 0 or 1 then there is no switching occurring and therefore is no current ripple. As the duty cycle changes from the 0 towards 1 the current ripple amplitude increases up to a maximum at a duty cycle of 0.5.

• Move the red time line to view the different current paths.
• Change the input voltage level to view how the load current and the current ripple magnitude varies.
• Vary the switching frequency and determine the influence that it has on the current ripple amplitude.
• Change the duty cycle and see how the current ripple changes. At what duty cycle is the current ripple the largest?
• Vary the load resistance or therefore the load current. Does this change the current ripple amplitude?