D.C. Series excited traction motor capable of operating with a continuous current power supply

A direct current, series excited traction motor circuit, comprising:

• an armature coil;
• first and second field coils connected in series with said armature coil and with each other to generate additive magnetic flux;
• a smoothing coil connected in series with said armature and field coils;
• a diode connected in parallel with the series connection of said armature, field and smoothing coils;
• a current chopper for controlling the supply of direct current to said coils;
• and
• a current shunting device connected in parallel with said first field coil to regulate the total field flux, said shunting device operating to conduct current with the same operating frequency as said current chopper and to block shunt current when said current chopper is not conducting.

A direct current, series excited traction motor circuit, comprising:

• an armature coil;
• first and second field coils connected in series with said armature coil and with each other to generate additive magnetic flux;
• a smoothing coil connected in series with said armature and field coils;
• a diode connected in parallel with the series connection of said armature, field and smoothing coils;
• a current chopper connected in parallel with said first field coil;
• and
• a current chopper for controlling the supply of direct current to said coils.

A direct current, series excited traction motor circuit, comprising:

• an armature coil;
• first and second field coils connected in series with said armature coil and with each other to generate additive magnetic flux;
• a smoothing coil connected in series with said armature and field coils;
• a diode connected in parallel with the series connection of said armature, field and smoothing coils;
• a plurality of resistances connected in parallel with said first field coil and one another, each resistance being provided with a series connected switch;
• and
• a current chopper for controlling the supply of direct current to said coils.