| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve efficiency of a converter by forming a snubber circuit of self-arc-extinguishing type element out of a DC circuit consisting of a diode and a capacitor, and forming a voltage clamp circuit consisting of a snubber capacitor 3 out of a resistor, a switching element and a control circuit. SOLUTION: An overvoltage control circuit is constituted of a snubber circuit consisting of a series circuit having a snubber diode 2 and a snubber capacitor 3 parallel-connected to a self-arc-extinguishing type element 1, a series circuit having a resistor 9 and a switching element 11 parallel-connected to the snubber capacitor 3, and a voltage clamp type snubber circuit which clamps the voltage of the snubber capacitor 3 to a fixed value or lower by on-off-controlling the switching element 11 according to the voltage of the snubber capacitor 3 and spending the energy of the snubber capacitor 3 with the resistor 9. It is thus possible to improve efficiency of a small converter suitable for forming a power converter by serial-connecting a plurality of self-arc-extinguishing type elements such as IGBT.</p> |
