Design of a three-level inverter with several modules
11.4.3Current source inverter (CSI)
Whilst the DC-bus voltage is kept constant by the DC-bus capacitor in voltage source
inverters, current source inverters (CSI) have a different principle in the fore. InCSI, the
DC-bus current is kept more or less constant. For this purpose, an appropriately sized
choke is inserted in theDC-bus.
Each IGBT of the current source inverter part bridge requires a series diode. This diode
is necessary, because a negative voltage can appear across a switch during some time
of the PWM control
As long as reverse blocking IGBTs are not commercially available,
a discrete solution is required.
An example of theCSI was already presented i
The series diode in a CSI topology with thyristors, however, serves the commutation along with a commutation