Setting up thedouble pulse test
As shown i
the components required to set up the test are:
DC power supply
Device under test (DUT)
Voltage and current measurements are also required. Depending on whether the upper
) or the bottom IGBT/diode (T
) is being dealt with, the load is
switched to DC- (section B) or DC+ (section A) of the DC-bus and either the upper or
the bottom IGBT selected. The other IGBT is clamped with a negative voltage. It is not
advisable to set the gate of this IGBT to 0V, as otherwise stray effects as described in
The capacitors of theDC-bus are chargedwith aDChigh-voltage source to the required
voltage via an adjustable, limited current. After the capacitors are charged, the power
supply should be separated from the capacitor bank and/or the charging current limited.
In case of a fault, then no or only a very low level of energy is replenished in the DC-
bus. It is recommended to use a power supply with integrated current control
. It is also necessary to ensure that the capacitor bank has been discharged after
the test. As a rule, this is achievedwith a discharge resistor betweenDC+ andDC-. The
for example, can be an IGBT.
The design of the DC-bus with its inductive behaviour is critical to the switching
behaviour of the IGBTs and diodes. This should always have the lowest inductance
possible, but should also correspond to the intended application.