The invention discloses a test circuit and method for testing the on-off characteristics of a converter valve. In the test circuit, the positive
electrode of a DC power supply in an energy supplementloop is connected to the
anode of a first
thyristor; one end of a
recovery valve in a
recovery loop is connected to one end of an
inductor and the
cathode of the first
thyristor, and the other end ofthe
recovery valve is connected to the negative
electrode of the DC power supply; one end of an H-
bridge circuit in an output loop is connected to the other end of the
inductor, the other end of the H-
bridge circuit is connected to the negative
electrode of the DC power supply, the H-
bridge circuit comprises a first sub-module comprising a first
capacitor and a first switch
assembly and a second sub-module comprising a second
capacitor and a second switch
assembly, and the
capacitance of the first
capacitor is different from that of the second capacitor; a load loop comprises a to-be-tested valve
test object, which is connected to two ends of the H-bridge circuit. By implementing the invention, a
test platform which can be periodically operated and of which the turn-on
voltage is differentfrom the turn-off
voltage is built, and the on-off characteristics of the valve and the
electrical performance of internal parts can be tested in a targeted manner.