Patent ID: 6439347
Filing Date: 2002-08-27
Classification: B66B

Abstract:
An elevator control apparatus comprising:a converter for rectifying AC power to produce DC power; an inverter for converting DC power into AC power having a variable voltage and a variable frequency; DC buses connecting the converter to the inverter; a power storage unit connected across the DC buses for storing DC power and for supplying DC power to the buses; a controller for controlling a motor operating an elevator, the motor being driven by the AC power having variable voltage and variable frequency, during a powered operation of the elevator and generating power during a regenerative operation of the elevator; a required power computing circuit for computing required power as power required by the elevator based on a speed command for controlling speed of the elevator and supplied to the controller and, through the controller, to the required power computing circuit; a charge/discharge control circuit maintaining a bus voltage across the buses, at a preset voltage, not less than a voltage obtained by rectifying the AC power, receiving the bus voltage as a feedback input and receiving the required power computed as another input, and issuing a drive signal for charging the power storage unit with regenerative electric power if the power required by the elevator is negative, meaning regenerative electric power is being generated by the motor; and a charge/discharge circuit for charging the power storage unit with the regenerative electric power in accordance with the drive signal.