Bidirectional DC/DC Converters

Brief description of bidirectionality in DC Converters and common applications

Unidirectional DC/DC converters have traditionally been used to adapt voltage levels and supply low power devices (PLC, control boards, relays, peripherals...) from different voltage sources. As their name implies, the energy flow is unidirectional allowing the energy to flow from the power source to the load and not from the load to the power source.

When the power source and the load can supply and absorb energy the energy flow can happen in both directions and a bidirectional DC/DC converter should be found in between.

With the development in the battery and energy storage field in the last decades and their use in an increasing amount of applications, such converters have been gaining more interest.

There are two main groups of DC/DC converters, isolated and non-isolated. The non-isolated, traditional main topologies such as buck or boost (and their derivatives) do not have bidirectional power flow capability. This limitation is caused by the presence of diodes in the topology that prevent reverse current flow, but in general these diodes can be replaced by switching devices to transform them into bidirectional converters.