In order to verify the explored relationship between the
maximum did/dt and diode chip temperature Tj during the
recovery period, a high power device test bench in Fig.2 is
used. The experimental waveforms of diode reverse recovery
current id and collector voltage vce under different diode chip
temperatures at Vdc=1600V and IL=500A are shown in Fig.4.
dt
di Lv d
eE - eE ×=
Figure.3. P-i-N diode reverses recovery waveforms and IGBT voltage
waveforms.
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The bus capacitors are 1000µF, to maintain the bus voltage.
The load inductor is 400µH to ensure near constant current
during the tested switching period. The inspected P-i-N
diode DM temperature is defined as TD, and the chip
temperature is controlled by a heating plate and varied
between 25o
C to 125o
C by averaging successive regulation,
meanwhile the temperature of the enabling IGBT module is
maintained at 25o
C. In this way, influence on the reverse
recovery process caused by the IGBT characteristics is
eliminated. From Fig.4, the current waveforms before the
peak are the same because of the unchanged enabling IGBT
temperature and the fixed external circuit parameters. The
peak reverse recovery current increases from 400A