In　this　study,　a　new　dual-active　soft-switching　converter　is　proposed　to　improve　conversion　efficiency　and　extend　the　load　range　for　an　MTEM　electromagnetic　transmitter　in　geological　exploration.　Unlike　a　conventional　DC/　DC　converter,　the　proposed　converter　can　operate　in　passive　soft-switching,　single-active　soft-switching,　or　dual-active　soft-switching　modes　depending　on　the　change　in　load　power.　The　main　switches　and　lagging　auxiliary　switches　of　the　converter　can　attain　soft-switching　over　the　entire　load　range.　The　conduction　and　switching　losses　are　greatly　reduced　compared　with　those　of　ordinary　converters　under　the　action　of　the　cut-off　diodes　and　auxiliary　windings　coupled　to　the　main　transformer　in　the　auxiliary　circuits.　The　conversion　efficiency　of　the　proposed　converter　is　significantly　improved,　especially　under　light-load　conditions.　First,　the　working　principle　of　the　proposed　converter　is　analyzed　in　detail.　Second,　the　relationship　between　the　different　operating　modes　and　the　load　power　is　given　and　the　design　principle　of　the　auxiliary　circuit　is　presented.　Finally,　the　Saber　simulation　and　experimental　results　verify　the　feasibility　and　validity　of　the　converter　and　a　50　kW　prototype　is　implemented.