Abstract: An apparatus for controlling an alternating current (A.C.) powered elevator includes a converter for converting A.C. power from A.C. power sources into direct current (D.C.) power and an inverter for converting the D.C. power into A.C. power of variable voltage and variable frequency. The converted A.C. power drives an induction motor to operate an elevator cage. The apparatus calculates a current command value from a speed command value and the speed of the motor and compares the current command value with the output current of the inverter. The apparatus further includes a conversion switch which produces an exciting current component switching command when operated and computing means for receiving the speed command value, a speed signal, and the exciting current component switching command and for calculating the current command value.

Abstract: An apparatus for controlling power conversion from alternating current (A.C.) to direct current (D.C.) by a converter has a D.C. voltage detector connected to receive a D.C. output of the converter for detecting the D.C. side voltage of the converter, a phase detector connected to an A.C. power source for detecting the phase of the A.C. power source, and calculating means for making a first calculation of a first current command value based on the output of the D.C. voltage detector, a second calculation of a phase angle of the A.C. power source voltage based on the first current command value, and a third calculation of second current command values based on the phase angle of the A.C. power source voltage and the output of the phase detector.

Abstract: A speed control apparatus for an A.C. elevator according to this invention comprises integration circuits which integrate outputs of current detectors for detecting primary currents of an induction motor and which are reset at fixed periods, and holding circuits which hold outputs of the integration circuits for a predetermined time. Thus, the influences of the ripples of the currents by pulse width modulation are eliminated, and the digital conversions of the three-phase currents can be performed by a single analog-to-digital converter.

Abstract: A control apparatus for an A.C. elevator comprises resistances connected between an A.C. power source and a converter, a detection device to detect the build-up rate of the charged voltage of a smoothing capacitor, and control means to generate a signal for closing a contact interposed between the A.C. power source and the converter, when the output of the detection device is not greater than a predetermined value. The detection and control devices are preferably provided by a microcomputer.

Abstract: A speed control apparatus for an elevator utilizing variable command values of the primary current of an induction motor for controlling the operation of the motor. When the cage is running at a rated speed, the terminal voltage of the induction motor is detected and supplied to a microcomputer to calculate an exact secondary resistance with respect to the temperature condition of the induction motor so as to determine the aforementioned command value of the primary current that is necessary for high speed precision control.

Abstract: A speed control apparatus for an elevator in which a temperature detector for detecting the ambient temperature of an induction motor is disposed, and an arithmetic unit employing a microcomputer is additionally furnished with the function of evaluating the component of temperature rise of a rotor and obtaining the resistance value of the rotor by the use of this component of temperature rise and the temperature detection signal of the temperature detector, to evaluate the optimum instantaneous current command by the use of the temperature-compensated resistance value, whereby the overvoltage and the insufficient torque of the induction motor can be obviated.

Abstract: In an elevator speed control apparatus wherein an output signal of a speed detector is sampled at a predetermined interval, and an output signal obtained by processing the sampling is applied to an inverter so as to perform a slip frequency control of an induction motor; correction means to receive the speed detector output signal sampled at the predetermined interval, to differentiate it to generate a differential signal and to deliver the differential signal as a correction signal is provided, so that a magnitude by which a rotational speed of the induction motor changes after the output signal of the speed detector has been fed into a microcomputer until the control signal is applied to the inverter is corrected, whereupon the signal for the speed control is delivered to the inverter, thereby to correct the lag of speed detection attributed to the sampling control.

Abstract: A speed control apparatus for an elevator is so constructed that an operating period of time is limited on the basis of a predetermined current command value or an output from a detector for detecting current to be supplied to an induction motor, thereby to render a load time factor of the induction motor a predetermined value or less and to maintain at or below a permissible value a temperature rise value based on a quantity of heat generated by a winding of the induction motor.Thus, the induction motor is prevented from burning even when the induction motor is operated at low speed in, for example, a manual operation mode for installation, maintenance and inspection, or the like.

Abstract: An inverter, which supplies A.C. power to a motor for driving the cage of an elevator, is feedback-controlled by detecting the A.C. power by means of a detector. The detector provides an output (offset voltage) even when the operation of the inverter is at a stop. The output value fluctuates in accordance with the changes of circumstances such as temperature changes, and the inverter is affected by the fluctuations, so that the inverter generates power with which the motor produces a torque ripple. In order to solve this problem and to perform an operation of reduced torque ripple, the offset voltage of the detector is sensed, and a drive control signal for the inverter is properly changed on the basis of the sensed offset voltage.

Abstract: The disclosed Leonard type elevator system comprises a reversible converter for controllably driving a DC motor, and an AC voltage detector and a DC voltage detector connected to the AC and DC sides of the converter respectively for detecting the voltages developed on the respective sides of the converter. When a difference in detected voltage between the two detectors exceeds a predetermined magnitude due to a decrease in the AC source voltage, a comparator produces an output serving to disconnect the DC motor from the converter. Also the comparator may produce such an output when the converter receives regenerative power from the DC motor.