The　actuator　drivers　are　rarely　transplanted　among　different　contactors　because　the　self-tuning　of　excitation　control　parameters　either　takes　a　long　time　or　is　relevant　to　many　contactor　structural　parameters.　An　adaptive　actuator　driver　for　ac　contactors　is　proposed　based　on　the　coil　impedance　estimation　and　mathematical　equations　between　the　coil　impedance　and　excitation　control　parameters.　The　coil　impedance　estimation　and　its　error　correction　are　established　through　the　voltage　balance　equation　when　the　contactor　is　in　the　open　position.　The　coil　inductance　estimation　is　established　through　the　zero-state　response　equation　when　the　contactor　is　in　the　closed　position.　The　mathematical　equations　are　established　based　on　the　equivalence　of　the　electromagnetic　force　under　different　excitation　methods,　the　power　consumption　model,　and　the　control　system＇s　transfer　function.　A　geometric　feature　of　the　flux　linkage　waveform　is　established　to　identify　whether　a　contactor　is　in　the　closed　position　and　realize　the　self-transition　of　the　driver＇s　working　state.　Then,　self-tuning　regulators　for　the　excitation　control　parameters　are　realized.　This　driver　has　a　plug-and-play　function　for　ac　contactors　and　can　reduce　the　contactor＇s　power　consumption.　This　driver　may　be　prospectively　reduced　to　a　chip.　©　1982-2012　IEEE.