Method and apparatus for controlling a turn-off power converter valve having the series connection number of two or greater

The invention relates to a method and device for controlling a power converter valve that can be turned off and has a number of series circuits amounting to two or more. Each non-engaging power semiconductor switch of the power converter valve has an active collector-emitter limiting circuit. According to the invention, when a rising edge of an available control signal (UASt) occurs, a predetermined value (UCEref1) of the reference limiting voltage (UCEref) of the active collector-emitter limiting circuit is brought down to a lower value (UCEref2) and increased to said predetermined value (UCEref1) during the turn-off process. As a result, voltage sharing between the two non-engaging power semiconductor switches (T1o, T2o, T3o; T1u, T2u, T3u) of a power converter valve that can be turned off and has a number of series circuits amounting to two or more can be balanced out by means of a turn-on command.