| Abstract |
An experimental converter (3-phase, 220 V, about 6-8 kVA) was used to demonstrate the characteristics of FET technology in its high voltage region. When utilizing the inverse diode specific to FETs, a configuration without protection circuits can be realized using FRED FETs. The dynamic properties obtained are such that the switching and insertion losses are equal between 80 and 120 kHz, depending upon the driving speed, and minimum turn-on times of around 0.5 us with a resulting linear distortion of only 10%. A low-inductance design reduces overshoots so far as to allow approximately 90% utilization of the transistor blocking capability. This also applies in the case of short-circuiting. An inductance of 2uH is sufficient to maintain the short-circuit currents in the permissible region for the transistors. Guidelines can be derived from this example for converters of other types also, such as DC/DC converters and sine-wave generators. |
