This paper analyzes the runaway phenomenon and its causes of the single-phase half-controlled-bridge commutated circuit, describes the functions of the fly-wheel diode, and puts forward some corresponding measures according to the features of the trigger circuit of double-base diode and the peculiarities of thyristor.

For one kind of high current diodes composed of a ceramic-metal welding water-vacuum interface,a cover sealing structure was proposed and evaluated.

The electrical parameter of the rectifier diode should be reflected with its absolute maximum ratings and electrical characteristics , while the absolute maximum ratings should be reflected with results of electrical characteristics parameter after testing.