Elevator control device

An elevator control device for reducing abrupt state variations in a car of an elevator, comprising:

• a current detecting circuitry to detect a drive current of a motor configured to drive a sheave to rotate, the sheave having a rope looped therearound, the rope suspending, on one side and the other side thereof, the car and a counterweight, respectively, through intermediation of the sheave;
• a velocity computing circuitry to compute a velocity signal of the motor based on output of a rotation amount detecting circuitry to detect a rotation amount of the motor, the rotation amount detecting circuitry including an encoder connected to the motor;
• a velocity command generating circuitry to generate a velocity command signal for the motor;
• a velocity controlling circuitry to output, based on the velocity command signal and the velocity signal, a velocity control signal so that the velocity signal follows the velocity command signal, to thereby control a velocity of the motor;
• a current controlling circuitry to drive the motor so that the drive current follows a torque current command signal input thereto;
• a brake controlling circuitry to control switching between a releasing state and a braking state of a brake configured to brake a rotation of the motor;
• a brake state command generating circuitry to output, to the brake controlling circuitry, a brake state command signal for switching between the releasing state and the braking state of the brake;
• and
• an unbalance torque estimating circuitry to estimate an unbalance torque in the motor caused by a weight difference between the car and the counterweight based on a first time period from an output change of the brake state command signal for switching an operation state of the brake from the braking state to the releasing state to a time when the motor starts a rotating operation along with release of the brake, and a positive or negative sign of the velocity signal obtained when the motor starts the rotating operation, and to output an unbalance torque estimation signal being an estimation result,
• wherein the unbalance torque estimating circuitry
• receives the brake state command signal and the speed signal as inputs,
• measures the first time period based on the brake state command signal and the speed signal,
• determines whether the sign of the unbalance torque is positive or negative based on a positive or negative sign of the velocity signal obtained when the motor starts the rotating operation, and
• estimates the unbalance torque from the first time period and a positive or negative sign of the unbalance torque, and outputs the unbalance torque estimation signal.