Multi-channel　transient　electromagnetic　(MTEM)　is　an　artificial　source　electromagnetic　detection　method,　the　transmitter　injects　the　high-power　pseudo-random　binary　sequence　(PRBS)　signals　with　different　coding　frequencies　into　the　earth　to　obtain　the　geological　structure　and　the　mineral　resources.　However,　the　current　transmitters　have　many　problems,　such　as　small　power-density,　low　efficiency,　and　poor　quality　output　signals.　A　novel　dual-active　soft-switching　converter　can　significantly　reduce　the　circuit　loss　and　achieve　stable　output　from　nearly　zero　to　full　load.　Because　of　the　proposed　converter　containing　18　operating　modes　in　a　duty　cycle,　it　cannot　be　directly　modeled.　Based　on　the　model　of　the　full-bridge　hard-switching　converter,　the　steady-state　and　low　frequency　small-signal　model　of　the　proposed　converter　is　established　by　analyzing　the　influences　of　resonant　inductance,　input　voltage　and　output　current　fluctuations　on　the　effective　duty　cycle.　Finally,　the　simulation　and　experimental　results　verify　the　validity　of　the　model,　and　a　50kW　principle　prototype　is　implemented.