A voltage source converter includes a converter limb having limb portions separated by an AC terminal and extending between DC terminals, each limb portion including a primary switching element to switch the limb portion into and out of circuit. The converter further includes an auxiliary limb. The primary switching element of each limb portion is switchable to switch the auxiliary limb into and out of circuit with the corresponding limb portion. The converter further includes a control unit to, in one mode, inject a circulation current that flows in one direction in one of the limb portions and minimize a current flowing in the opposite direction in that limb portion. Each primary switching element switches the respective limb portion into or out of circuit following the minimization of the limb portion current by the circulation current.