A DC motor includes a core, two bifurcated branching portions, an inner coil, and an outer coil. The core includes teeth. Each tooth includes a distal end and a basal end. The branching portions are located at the distal end. The inner coil is wound around the basal end. The outer coil is wound around each of the branching portions of the tooth and a branching portion of an adjacent one of the teeth. The inner coil and the outer coil each have a number of turns that is adjusted so that an inductance of the inner coil conforms to an inductance of the outer coil.

A DC motor includes a core, two bifurcated branching portions, an inner coil, and an outer coil. The core includes teeth. Each tooth includes a distal end and a basal end. The branching portions are located at the distal end. The inner coil is wound around the basal end. The outer coil is wound around each of the branching portions of the tooth and a branching portion of an adjacent one of the teeth. The inner coil and the outer coil each have a number of turns that is adjusted so that an inductance of the inner coil conforms to an inductance of the outer coil.

An electric motor includes a stator and a rotor. The stator has a plurality of low speed windings and a plurality of separate high speed windings. A first type of thermal overload protector is coupled with at least one of the low speed windings and a second type of thermal overload protector is coupled with at least one of the high speed windings.

An electric motor includes a stator and a rotor. The stator has a plurality of low speed windings and a plurality of separate high speed windings. A first type of thermal overload protector is coupled with at least one of the low speed windings and a second type of thermal overload protector is coupled with at least one of the high speed windings.

Systems and methods, for controlling an output torque of a permanent magnet direct current (PMDC) machine includes a PMDC motor that includes a plurality of winding sets and a controller. The PMDC motor is configured to generate the output torque. The controller is configured to: determine, for a first winding set of the PMDC motor, a first voltage command based on a first input torque command signal and a back-EMF drop voltage of the first winding set; determine, for a second winding set of the PMDC motor, a second voltage command based on a second input torque command signal; and selectively control the PMDC motor according to the first voltage command and the second voltage command.

Systems and methods, for controlling an output torque of a permanent magnet direct current (PMDC) machine includes a PMDC motor that includes a plurality of winding sets and a controller. The PMDC motor is configured to generate the output torque. The controller is configured to: determine, for a first winding set of the PMDC motor, a first voltage command based on a first input torque command signal and a back-EMF drop voltage of the first winding set; determine, for a second winding set of the PMDC motor, a second voltage command based on a second input torque command signal; and selectively control the PMDC motor according to the first voltage command and the second voltage command.

An electric drive apparatus includes a DC motor for driving the electric device; a DC power source for outputting constant-voltage DC power to the DC motor; and a chopper for converting the constant-voltage DC power into variable-voltage DC power according to a driving signal and providing the variable-voltage DC power to the DC motor. The DC motor has 2j armature winding branches, each of which consists of m windings, 2jm commutator segments connected to the windings, and two brush sets respectively connected to two power line sets of the DC motor and in contact with the commutator segments.

An electric drive apparatus includes a DC motor for driving the electric device; a DC power source for outputting constant-voltage DC power to the DC motor; and a chopper for converting the constant-voltage DC power into variable-voltage DC power according to a driving signal and providing the variable-voltage DC power to the DC motor. The DC motor has 2j armature winding branches, each of which consists of m windings, 2jm commutator segments connected to the windings, and two brush sets respectively connected to two power line sets of the DC motor and in contact with the commutator segments.

A double-stator rotating electric machine includes a rotor, an outer stator disposed radially outside the rotor with an outer gap formed therebetween, and an inner stator disposed radially inside the rotor with an inner gap formed therebetween. The outer stator has an outer multi-phase coil wound thereon, and the inner stator has an inner multi-phase coil wound thereon. Moreover, the inner gap formed between the inner stator and the rotor is set to be larger than the outer gap formed between the outer stator and the rotor.

A DC electric drive apparatus and an electric device. The DC electric drive apparatus (10) is provided in an electric device to drive the electric device, comprising: a DC motor (11), for driving the electric device; a DC power source, for outputting constant-voltage DC power to the DC motor; and a chopper (12), for converting constant-voltage DC power into variable-voltage DC power according to a driving signal and providing variable-voltage DC power for the DC motor, wherein, the DC motor has 2j armature winding branches (16) each composed of m windings (16a), 2jm commutator segments connected to the windings, and two brush sets (17) respectively connected to two power line sets of the DC motor and in contact with the commutator segments; each of the brush sets comprises j brushes (18); each of the power line sets comprises j power lines; the chopper has k bridge arm portions (19), and each of the bridge arm portions comprises j bridge arm units (20) connected to j power lines of one power line set in one-to-one correspondence; each of bridge arm units outputs a current for two armature winding branches through correspondingly connected power lines, and the armature winding branches generate output torques to drive the electric device. Both j and m are positive integers not less than 2, and k is 1 or 2.