In this applet the influence the 3-phase bridge rectifier has on the level of voltage distortion for a real mains supply is examined. Since the mains voltage source has finite impedance there will be distortion in the voltage at the point at which the rectifier connects to the mains. For more of an explanation of how this distortion is caused, please see the single-phase mains voltage distortion applet. 

When the AC inductance is very small the distortion is influenced mainly by the voltage of the capacitor. This is because when the diodes are conducting the voltage appearing at the input to the bridge rectifier is the capacitor voltage. Since the inductors are small then a significant amount of this voltage appears at the point of common coupling. By increasing the size of the AC inductors, this now provides greater impedance between the rectifier input and the mains coupling point, thus reducing the level of voltage distortion.

• Shift the operating point of the 3-phase rectifier by dragging the red line on the waveforms. As the line moves notice how the current commutates between the different diodes connected to each of the phases.
• The value of the 3 AC side inductors can be simultaneously adjusted by dragging the red bar on the top inductor. Notice how the inductor value changes the current waveform shape from a peaky shape to a more continuous waveform shape, and how the voltage waveform at the point that the other load connects also changes.
• The load resistance can also be changed. The level of output current also has an effect on the level of voltage distortion on the main supply. Does the voltage distortion increase or decrease with load current?