A　novel　rotor　position　angle　estimator　is　proposed　to　achieve　zero　and　very　low　operation　speed　for　sensorless　direct　torque-controlled　electrically　excited　synchronous　motor　(EESM)　drive.　First,　high-frequency　ripple　current　is　injected　into　rotor　winding,　and　second,　using　closed-loop　torque　control,　high-frequency　component　is　injected　into　electromagnetic　torque　to　produce　high-frequency　stator　current　only　in　d-axis　direction.　At　last,　the　rotor　position　angle　is　estimated　with　phase-locked　loop　principle.　The　stator　flux　and　electromagnetic　torque　are　calculated　with　stator　flux　current　model　and　estimated　rotor　position　angle,　and　then　a　sensorless　direct　torque-controlled　EESM　drive　is　constructed　with　estimated　flux　and　torque.　The　experimental　results　show　that　the　proposed　sensorless　EESM　drive　system　can　operate　at　zero　and　very　low　speed.　©　1986-2012　IEEE.