A voltage source converter of the controlled transition bridge type, having three phase limbs, each phase limb having a high &de director switch (Sw1 Sw3, Sw5) and a low side director switch (Sw4, Sw6, Sw2) connecting a respective DC terminal (DC+, DC−) to an AC node for that phase limb. Chain-link circuits for each phase limb comprise a plurality of series connect cells, each cell having an energy storage element that can be selectively connected in series or bypassed. The chain-link circuits are operated in a voltage mode to provide a defined voltage transition at the AC node during a transition between one director switch being turned off and the other director switch being turned on. Chain-link circuits are connected to a common node such that, in use, a current can flow from one phase limb to another via the respective chain-link circuits.