Matrix Converters achieve three-phase AC/AC conversion without any intermediate energy storage element. This has the potential to increase power density (output power per converter volume) significantly. Furthermore, omitting the electrolytic capacitor in the DC-link will improve the system reliability. The main idea of the Conventional Direct Matrix Converter is to be able to connect each input phase directly to each output phase at any time in order to put together a three-phase output voltage system as needed for the variable-speed drive. 

A disadvantage is the complicated multi-step current commutation scheme where the current control always has to make sure that free-wheeling can occur. A large number of states must be considered, and signs of currents and voltages have to be taken into account when defining the switching pattern. A current control error will result in the immediate destruction of power switches. You can experiment with the switching sequence for a multi-step commutation in this applet.

• Find the correct switching sequence for a current commutation without the destruction of the power semiconductors.
• Click onto the red gate-symbols of the 4 transistors to switch them on or off. On-state is marked with a green circle.
• The applet will keep you informed if you made a mistake.
• 'Reset' anytime and try again!