Power unit testing circuit for IGCT (integrated gate commutated thyristor) three-level medium voltage frequency converter

The invention relates to a power unit testing circuit for an IGCT (integrated gate commutated thyristor) three-level medium voltage frequency converter. The frequency converter is technically characterized in that an input switch Q1 is connected with a voltage regulator T1 and then is respectively connected with a transformer T11 and a transformer T12 by virtue of a branch switch Q11 and a branch switch Q12, the transformer T11 and the transformer T12 are respectively connected with a rectifier A and a rectifier B, the rectifier A and the rectifier B are respectively connected with a filter capacitor CA and a filter capacitor CB in parallel, a discharge circuit is respectively connected with the two ends of the filter capacitor CA and the filter capacitor CB in parallel, the discharge circuits are connected with a grounded circuit, the two filter capacitors are connected with a tested power unit by virtue of a di/dt buffer circuit, the tested power unit is connected with a test load, and a controller for test is connected with the discharge circuits and the tested power unit. By adopting the power unit testing circuit provided by the invention, a temperature rise test of the tested power unit and an on-off test of a single-IGCT device and a bridge arm are realized, and the power unit testing circuit provided by the invention has the characteristics of simple test circuit, low total capacity, low energy consumption, no pollution to a power grid, convenience in operation and the like.