A　novel　rotor　position　angle　estimator　is　proposed　to　achieve　zero　and　very　low　operating　speed　for　a　sensorless　direct　torque　controlled　electrically　excited　synchronous　motor　(ESM)　drive.　Firstly,　high-frequency　ripple　currents　are　injected　into　the　rotor　circuit,　and　secondly,　using　the　torque　close-loop,　the　high-frequency　component　is　injected　into　torque　to　produce　high-frequency　stator　currents　only　in　the　d-axis　direction.　At　last,　the　rotor　position　angle　is　estimated　with　the　phase-locked　loop　principle.　The　stator　flux　and　torque　are　calculated　with　the　stator　flux　current　model　and　the　estimated　rotor　position　angle,　and　then　the　sensorless　direct　torque　controlled　ESM　drive　is　constructed　with　estimated　flux　and　torque.　The　results　of　experiments　show　that　the　proposed　sensorless　drive　system　can　operate　at　the　zero　and　very　low　speed　under　any　load.　©　2015　Chin.　Soc.　for　Elec.　Eng..