Abstract: An electrical drive vehicle with an onboard battery and a D.C. propulsion motor having means for automatically switching the D.C. motor from a series field operation to shunt field operation upon the operator actuating the braking means to convert the kinetic braking energy to electrically energy for charging, via an intermediate storage means, the onboard battery. The switching means is a variable duty cycle transistor switching means controlling the excitation of the D.C. motor in the shunt field mode.

Abstract: An on-board quick charge circuit for an electric vehicle battery is incorporated in an electric vehicle having a solid state dc chopper motor speed controller which may be connected in either a propulsion mode or in a battery charge mode. With the aid of an external donor battery at the charge station, load leveling at the utility grid is maintained irrespective of the instantaneous current demands in the battery charging process. Energy transfer from the donor battery to the on-board propulsion battery is controlled by solid state switching apparatus. Each time the switching apparatus conducts, energy as transferred from the donor battery to the on-board propulsion battery, and energy is additionally transferred and stored in the dc reactor associated with the dc chopper circuit of the vehicle propulsion system. The energy stored in the dc reactor is expended into the on-board propulsion battery when the switching apparatus is turned off.

Abstract: A typical "stand alone" precision power DC to AC solid state converter reres a higher DC supply voltage than is usually available from its utility power sources. The disclosed invention is a voltage boost circuit that provides the DC-bus voltage amplitude for precision power DC to AC solid state converters by transforming only the difference between the available raw power DC voltage bus and the required precision DC voltage amplitude. This DC voltage difference obtained by the circuitry of this invention is boot-strapped to the available DC bus to obtain the required precision DC voltage.