Overcurrent turn-off test method based on H-bridge test platform

The invention relates to an over-current turn-off test method based on an H-bridge type operation test platform, a test system comprises four bridge arm branches, a bridge arm 1, a bridge arm 3, a bridge arm 2 and a bridge arm 4 form a phase unit 1 and a phase unit 2 respectively, the middle points of the two phases are connected through a load reactor, and each bridge arm is composed of an MMC valve and a bridge arm reactor. The two phase units have a common direct current end and are connected with a direct current power supply through a smoothing reactor, and the direct current power supply is used for pre-charging the sub-module and supplementing active loss in the test process. According to the method, a target value control method is applied, the control logic of four bridge arm test objects is changed in the test operation process, the overcurrent turn-off test of the first bridge arm and the second bridge arm and the overcurrent turn-off test of the third bridge arm and the fourth bridge arm are compl