Abstract: A polyphase induction motor propels an elevator car. The motor is powered by a multiphase inverter which receives power from a battery. The inverter is controlled in such a way as to control the frequency and amplitude of the power supplied to the motor in order to control the motor's speed, acceleration, and slip. That inverter control is accomplished by sensing the motor's speed and in response providing predetermined slip and torque signals. The slip can be controlled over a range which can provide negative slip, by which power is regenerated into the battery, which is thereby charged, and positive slip for motoring torque. A charger also charges the battery. The motor and its controls are thereby ostensibly isolated from the power system that supplies power to the charger, the battery handling the peak power requirements. Thus, little noise is injected into the power system. This motor control system is thus efficient to operate, economical to build and very quiet.

Abstract: The current in the windings of a polyphase motor are individually sensed, and individual signals that indicate that current are provided. Using these signals, the difference between positive and negative current flow through the motor is determined, and if that difference exceeds a first level, for a preset duration of time, the motor is permitted to operate for a limited time. But, if it exceeds a second level, for a preset duration of time, the motor is slowed down in a programmed manner. Total current flow through the motor is determined from these signals as well, and if it exceeds a maximum for a preset duration of time, the motor is stopped in a programmed manner.

Abstract: A polyphase induction motor propels an elevator car. The motor is powered by a multiphase inverter which receives power from a battery. The inverter is controlled in such a way as to control the frequency and amplitude of the power supplied to the motor in order to control the motor's speed, acceleration, and slip. That inverter control is accomplished by sensing the motor's speed and in response providing predetermined slip and torque signals. The slip can be controlled over a range which can provide negative slip, by which power is regenerated into the battery, which is thereby charged, and positive slip for motoring torque. A charger also charges the battery. The motor and its controls are thereby ostensibly isolated from the power system that supplies power to the charger, the battery handling the peak power requirements.

Abstract: An elevator system is powered by a multiphased motor to which power is supplied from an inverter, which is powered by a battery. The collector-emitter voltage across the output transistors in the inverter is sensed as the transistors are turned on, and if the voltage does not drop to the saturation voltage within a certain time, the drive to the inverter is discontinued. If at any time while the transistors are in saturation saturation voltage rises, the drive is turned off. To start the drive, the transistors are permitted to turn on for a short interval of time. If, following that interval of time, the saturation voltage is not correct, the drive is turned off. The inverter has separate sections for driving each winding of the motor, and each of these sections has a separate power supply and fault detection circuit, which operates to measure the saturation voltage across the transistor and provide a fault signal which indicates that the drive should be terminated.

Abstract: A polyphase induction motor propels an elevator car. The motor is powered by a multiphase inverter which receives power from a battery. The inverter is controlled in such a way as to control the frequency and amplitude of the power supplied to the motor in order to control the motor's speed, acceleration, and slip. That inverter control is accomplished by sensing the motor's speed and in response providing predetermined slip and torque signals. The slip can be controlled over a range which can provide negative slip, by which power is regenerated into the battery, which is thereby charged, and positive slip for motoring torque. A charger also charges the battery. The motor and its controls are thereby ostensibly isolated from the power system that supplies power to the charger, the battery handling the peak power requirements. Thus, little noise is injected into the power system. Speed loop gain is adjusted depending upon whether the motor is motoring or regenerating.

Abstract: An elevator system is battery powered. The battery is charged by a battery charger and also regenerated by a polyphase motor which drives the car and which is inverter operated. The charge on the battery is controlled by sensing the battery voltage and, if the voltage is excessive for an interval of time, applying a load to the battery for an interval of time. The battery voltage may also be sensed by controlling the battery discharge in proportion to the excess voltage.