The invention discloses a
driving circuit of a bidirectional
thyristor in a composite switch, a three-phase intelligent commutation
system and a commutation method. The
driving circuit comprises parallel capacitors at two ends of the bidirectional
thyristor, wherein the bidirectional
thyristor is connected in series with a
resistor and a parallel
branch of a normally-open
relay and then is accessed to a A-phase, B-phase or C-phase circuit, and a piezoresistor is connected in series between the A-, B and C-phase circuit and a null line and among the A-phase circuit, the B-phase circuit and theC-phase circuit. By the
driving circuit, the working reliability of the circuit is ensured, and false triggering of a main circuit of the thyristor is prevented; the
resistor is connected in series with the main circuit,
interphase large current
short circuit probably occurring in two phases is prevented, the
resistor is circuit-shorted during the commutation process, the large-current commutationprocess cannot be affected, the reliability of the commutation circuit is improved, and meanwhile, the probability of a fault occurring in a power distribution network
system is prevented; and with the adoption of a low-
voltage and low-power trigger driving circuit, driving triggering is reliable, the output
voltage waveform distortion is small during the commutation process, and the influence ona user is small.