Abstract: A separately excited DC motor system is arranged to provide operation in a smooth, continuous electrical retarding mode. A series contactor connects the motor armature to a DC power source and is controlled so as to immediately open upon sensing of a need for electrical braking. Concurrently, power to the motor field is reversed so that no additional changes are required to brake to zero speed. Field current is modulated to control armature current so as to control braking effort. When speed falls below a value necessary to maintain armature voltage above battery voltage, the armature is cyclically short-circuited to boost armature current so that when the short-circuit is removed, the armature reactance forces current to continue for regeneration.

Abstract: A method for measuring and storing the state of charge of batteries, such as used in electric vehicles. The stored charge value is initially derived from the value of battery terminal voltage measured prior to connection of the battery to the load, e.g. the traction motor. While the battery is connected to the load, approximated state of charge values are periodically derived by adding a correction voltage, comprising the product of measured load current and of a predetermined value of internal resistance, to the measured terminal voltage of the battery. The stored and approximated state of charge values are periodically compared and the stored state of charge value is decremented by a predetermined increment in response to the stored charge value having exceeded the approximated state of charge value during each of a predetermined plurality consecutive comparisons.

Abstract: A method for operating an electronic control system for an operator controlled, electrically driven vehicle. The vehicle being powered by a direct current electric traction motor. The electronic control system includes a power source, a variable mark-space ratio power regulator responsive to a motor current command signal developed in response to the position of an accelerator, a direction selection means for providing signals indicative of the direction of motion of the vehicle, and a braking signal responsive to brake position. The electronic control system implements operation of the motor automatically in a propulsion mode, a regenerative mode, and a plug mode. The propulsion mode is either a series connected mode or a separately excited mode. The regenerative mode simulates the retarding effects of an internal combustion engine driven vehicle, while recover the kinetic energy of the vehicle by the generation of current to recharge the power source.

Abstract: An electrical braking control circuit for use in a control system for a direct current traction motor which may be employed, for example, to propel an electrically driven vehicle. The electrical braking controller of the invention initiates electrical braking in a plug mode of braking and then, when conditions are suitable for regenerative braking, causes a transition to regenerative braking, followed by return to a plug mode of braking whenever regenerative braking can no longer be efficiently achieved, all of which is carried out smoothly and efficiently without unduly wasting regenerative power.

Abstract: An electrical braking circuit provides smooth transitioning between regenerative and plug braking of a DC electric motor by use of a low ohmic value resistance path to maintain motor torque during transitioning. During initiation of electrical braking, a similar low ohmic resistance path momentarily connects the motor to a power source in order to establish proper magnetic flux in the motor to enable regenerative braking. Both resistance paths are disabled during motoring and braking modes of operation in order to minimize power loss in the resistance paths.

Abstract: A speed regulating circuit which regulates motor speed without the use of a speed feedback signal by adjusting the magnitude of motor current so as to maintain a predetermined relationship between motor voltage and current. A function generator generates a current reference signal as a function of motor terminal voltage. The relationship between terminal voltage and motor current is established by curve fitting of the motor volt-amp family of curves for constant motor speeds. The current reference signal controls a motor current control circuit, preferably a time ratio or chopper circuit in order to adjust motor current and to regulate motor speed. A closed loop current control loop is associated with the chopper circuit for adjusting motor current to the current reference value.