Abstract: In a thermal overload protection system three system variables are sensed and provide the inputs required for a calculation conducted in real time at one second intervals. The system variables include ambient inlet air temperature to the alternator, alternator stator winding embedded sensor temperature, and traction motor armature current. A traction motor current limit is calculated using the inlet air temperature and the sensor temperature. The thermal overload is then controlled in response to the traction motor current.

Abstract: Method and apparatus for optimizing power delivered by a prime mover-driven electric power alternator to an adjustable speed electric traction motor during high speed operation. The alternator is suitably controlled to deliver constant power if its output voltage does not exceed a first predetermined magnitude corresponding to a "corner point" speed of the motor and to limit the voltage magnitude when motor speed exceeds this corner point, thereby preventing excitation current from exceeding the maximum continuous field current rating of the alternator. As motor speed increases above corner point speed, less power is delivered to the motor, but the power reduction is minimized by increasing the voltage limit above the first predetermined magnitude. The amount of voltage limit increases, up to a predetermined maximum amount, is proportional to the amount load current in the motor decreases below its magnitude when motor speed equals corner point speed.

Abstract: An improved power supply and drive system for an elevator is disclosed. An electric motor is connected to an electrical power source for a building. The electric motor is mechanically connected through a start-up clutch and an override clutch to a bevel gear assembly. A flywheel is also mechanically connected to the bevel gear assembly. The bevel gear assembly is connected through a disconnectig clutch to a conventional Ward Leonard elevator drive system, which includes a generator and a hoist motor. The electric motor is sized to generate a power output representing the integrated or average requirement of the elevator system over its prolonged duty, typically one-fourth of the size required in conventional systems. The bevel gear assembly, the flywheel, and the various clutches are provided to store energy used to operate the elevator during the relatively brief power surge requirements of the elevator system.

Abstract: The present invention concerns a method for improving the dynamic converter drive for a direct current elevator motor, in which the said motor is controlled by adjusting the magnetization of the generator linked to the lifting motor, such adjustment being achieved by means of a power electronics stage controlled by the elevator speed control system, using at least elevator speed and motor current consumption (or other current information proportional thereto) as feedback parameters.

Abstract: A variable frequency drive for a motor-generator/alternator set which is used to supply electrical power to computer or data processing equipment. Power failures in commercially supplied power results in aberrations and erroneous computations in computers and data processing equipment. An induction motor is used to drive a generator/alternator. The induction motor is driven below the synchronous speed of the generator/alternator and a variable speed drive increases the velocity supplied to the generator/alternator, preferably to a point above its synchronous speed. Therefore, when there is a commercial power failure, the generator/alternator remains within a desired frequency range for a longer period of time than a comparable generator/alternator driven at synchronous speed.

Abstract: A control method and circuit providing smooth transition between two regulating modes involving two regulating parameters, one active and one inactive. The method comprises the steps of providing a reference signal and developing a signal representing the inactive parameter. The two signals are then compared to provide an inactive output signal that is indicative of any difference existing between them. Another signal is developed that represents the active parameter, and this signal is compared to the inactive output signal. The inactive output signal is then forced continuously to the value of the signal representing the active parameter when the values of the two signals are different. Change from the one parameter and mode to the other parameter and mode can now be made without a disturbing effect.

Abstract: In a speed feedback control system wherein a speed command signal and a speed feedback signal are compared and wherein the deviation between these signals is entered into a speed control unit, the speed signal is differentiated to apply speed damping in order to suppress the oscillations of the control system. In this case, while the speed command and the actual speed make a great difference transiently, the speed command is approximate to the sum between the speed feedback signal and the damping signal even transiently. Therefore, the speed command signal is compared with the sum between the speed feedback signal and the damping signal, and the fault of the speed control system is detected upon the fact that the deviation has exceeded a predetermined value.