Improve the power to weight ratio, efficiency and increase the life of motor and alternator is of paramount importance in design. In order to do that; I have successfully developed a new concept electric machine that provides up to 50% improvement in power to weight ratio and efficiency, after spending several years to research. Flexidrive (Electric motor) that will give torque on demand while accelerating and power on demand while cruising and Electric load on demand while regenerative breaking.

In this concept one armature is inside the stator as in normal motor but another armature is on outside the stator. Stator winding is common for both armature windings. Inside armature act as alternator and outside armature act as motor for normal operation. Flux path is continuous from inside armature to stator to outside armature. Shafts of both armatures are concentric. Details of concept are given in the figure below.

Assume middle rotor has permanent magnet, inner rotor has magnetizing coil and outer rotor too has magnetizing coil.

When we pass current through inner rotor, it rotates in counter clockwise at about 1000 rpm and middle rotor rotates in clock wise direction at 1000 rpm due to action and reaction. When we pass current through outer rotor, it rotates clock wise at 3000 rpm. Since outer rotors torque is same compared to middle rotor and inner rotor; and outer rotor’s speed is higher than inner ones’ power of outer rotor will be higher (about three times). This high power is useful for higher top speed.

Modes of operation
1) Electric current is applied on only one armature for normal cruising or highway mode. Since no load is applied on second armature there will not be any loss in electricity; even though current is generated in second armature.
2) Electric current is applied on coils of both armatures for acceleration and climbing
3) Electric load (Battery Charging) is applied on only one armature and current is applied on stator coil for normal regenerative braking. Since no load is put on second armature there will not be any loss in electricity; even though current is generated in second armature.
4) Electric load (Battery Charging) is applied on coils of both armatures coils and current is applied on stator for heavy braking or sudden braking.

Advantages
Since two different copper volumes are used for two different torques copper losses and iron losses will be minimum.

Different types of FlexiDrive can made using principle of DC motors, AC induction motors, Synchronous machines, reluctance motors and hysteresis motors and even as hybrid of these technologies.

1. In car electrical system is natively DC so it is economical to use DC motors to avoid expensive power electronics.
2. Failure of power electronics can cost even life for e.g. during regenerative braking failure of control unit can cost life
3. In AC induction motor speed has to increase beyond synchronous speed to generate electricity during braking.