in the same direction but decreases in amplitude exponentially while exiting from reactor 10 and irrespective of any small current changes reactor 10 as well as the armature of motor 1 represents a constant current source for a short interval this constant current source reverses its voltage polarity at its terminals and increases in amplitude until diode 8 conducts when diode 8 conducts the stored energy from both the reactor 10 and the motor 15 is returned to battery 2 which in turn accepts the charge in accordance to its condition of charge a considerable time prior to the depletion of the stored energy in reactor 10 and motor 1 transistor switch 3 is again closed and the recuperative energy cycle is repeated until the time mechanical braking energy has been depleted and the vehicle is near stand still since energy is recuperated as described above via the local loop of diode 8 and is independent of the battery voltage it follows that energy recovery is obtained over the entire speed range except when motor 1 is near stall recuperative energy braking is similarly obtained when the vehicle is propelled in the reverse direction in this mode the circuit functions are in the same manner as described above for the forward mode of recuperative braking operation except that contactor k4 and diode 9 are substituted for contactor k3 and diode 11 the magnitude of recuperated brake energy is a controlled variable and is a function of the conduction duty cycle of transistor switch 3 and the magnetic flux excitation of the shunt field the foregoing operation was described with contactor k3 forward mode or contactor k4 reverse mode connected to the common point of series 4 and the collector of transistor switch 3 connection 16 for a.