The applet shows simple square wave operation of an H-bridge. In the current path there are always two power semiconductors. If, for example, transistors s11 & s22 are on, and transistors s12 & s21 are off, the load voltage u2 will always be positive. Load voltage u2 is not dependent on the current flow direction. In case of positive current i2 > 0, the current will flow through the two transistors, and in case of negative current (i2 < 0), the anti-parallel diodes will be conducting. The H-bridge in square wave operation is an essential and basic building block of power converter systems. The current iDC is important for the life time of the DC capacitor and/or battery which can be typically found in such configurations. The i2/u2 - iDC/uDC diagram shows the operating points during operation.

• Change resistor and inductor values to influence the load current. The load voltage u2 is not dependent on the load.
• Drag the red time slider to investigate different current flow states. Note how the current path switches from transistors into anti-parallel diodes when load current i2 changes direction (makes a zero crossing).