Direct current motor

A direct current motor connected to at least one direct current power supply, comprising:

• a casing;
• m pairs of brushes fixed within the casing, wherein m is a positive integer greater than 1;
• a stator provided within the casing and including m pairs of main poles, each pair of main poles corresponding to one of the m pairs of brushes, and m first field winding units each corresponding to one of the pairs of main poles and to the pair of brushes to which the corresponding pair of main poles corresponds;
• and
• a rotor provided within the stator and including a plurality of armature windings, wherein each pair of main poles includes an S-polarity main pole and an N-polarity main pole neighboring each other in a circumferential direction of the stator,
• each of the main poles has a different polarity from neighboring main poles in the circumferential direction of the stator,
• each of the pairs of brushes comprises two brushes disposed at neighboring positions in the circumferential direction of the stator,
• each pair of brushes includes an S-pole corresponding brush corresponding to the S-polarity main pole of the corresponding pair of main poles and an N-pole corresponding brush corresponding to the N-polarity main pole of the corresponding pair of main poles,
• each first field winding unit comprises a first field coil wound around one of the main poles and a second field coil wrapped around the other of the main poles in the corresponding pair of main poles,
• the direct current motor is connected to m pairs of power output terminals of the at least one direct current power supply,
• each first field winding unit has a first end connected to one of the brushes of the corresponding pair of brushes and a second end which forms a first wiring terminal,
• the first end of each first field winding unit is connected to the S-pole corresponding brush of the corresponding pair of brushes, or the first end of each first field winding unit is connected to the N-pole corresponding brush of the corresponding pair of brushes,
• the other brush of each pair of brushes which is not connected to the first end of the corresponding first field winding unit is connected to a second wiring terminal,
• for each of the pairs of brushes, the first wiring terminal of the corresponding first field winding unit and the second wiring terminal connected to the other brush of the pair of brushes form a pair of external wiring terminals corresponding to the pair of brushes and to the pair of main poles corresponding to the pair of brushes, the motor having m pairs of external wiring terminals, and
• each pair of external wiring terminals is for connection to one of the pairs of power output terminals of the at least one direct current power supply in one-to-one correspondence.