An intelligent electronic device (IED) according to the present disclosure can estimate a full load rotor resistance value as a function of motor positive-sequence resistance. The IED may estimate the full load rotor resistance value by measuring zero-crossings of voltage after a motor disconnect. The IED may also acquire motor current and voltage measurements and calculate motor slip using the acquired motor current and voltage measurements and the estimated full load rotor resistance value.

A device and method for determining operating modes of an AC asynchronous three-phase motor in an escalator system and computer-readable storage medium on which a computer program for implementing the method is stored. The operating modes include a first operating mode and a second operating mode, the AC asynchronous three-phase motor adopts a triangular wiring mode and a star wiring mode in the first operating mode and the second operating mode, respectively, the device includes: a memory; a processor coupled with the memory; and a computer program stored on the memory and running on the processor, the running of the computer program causes: A. obtaining a slip rate of the AC asynchronous three-phase motor; and B. determining whether the AC asynchronous three-phase motor needs to be switched between the first operating mode and the second operating mode based on the slip rate.

A device and method for determining operating modes of an AC asynchronous three-phase motor in an escalator system and computer-readable storage medium on which a computer program for implementing the method is stored. The operating modes include a first operating mode and a second operating mode, the AC asynchronous three-phase motor adopts a triangular wiring mode and a star wiring mode in the first operating mode and the second operating mode, respectively, the device includes: a memory; a processor coupled with the memory; and a computer program stored on the memory and running on the processor, the running of the computer program causes: A. obtaining a slip rate of the AC asynchronous three-phase motor; and B. determining whether the AC asynchronous three-phase motor needs to be switched between the first operating mode and the second operating mode based on the slip rate.

A device and method for determining operating modes of an AC asynchronous three-phase motor in an escalator system and computer-readable storage medium on which a computer program for implementing the method is stored. The operating modes include a first operating mode and a second operating mode, the AC asynchronous three-phase motor adopts a triangular wiring mode and a star wiring mode in the first operating mode and the second operating mode, respectively, the device includes: a memory; a processor coupled with the memory; and a computer program stored on the memory and running on the processor, the running of the computer program causes: A. obtaining a slip rate of the AC asynchronous three-phase motor; and B. determining whether the AC asynchronous three-phase motor needs to be switched between the first operating mode and the second operating mode based on the slip rate.

A device and method for determining operating modes of an AC asynchronous three-phase motor in an escalator system and computer-readable storage medium on which a computer program for implementing the method is stored. The operating modes include a first operating mode and a second operating mode, the AC asynchronous three-phase motor adopts a triangular wiring mode and a star wiring mode in the first operating mode and the second operating mode, respectively, the device includes: a memory; a processor coupled with the memory; and a computer program stored on the memory and running on the processor, the running of the computer program causes: A. obtaining a slip rate of the AC asynchronous three-phase motor; and B. determining whether the AC asynchronous three-phase motor needs to be switched between the first operating mode and the second operating mode based on the slip rate.

The present disclosure provides an inverter control device for estimating the magnetic flux of a rotor, and calculating and compensating for a slip frequency on the basis of a torque current and a magnetic flux current, to control the speed of an electric motor. To this end, the present invention may comprise: a command voltage generation unit for outputting a three-phase PWM voltage with respect to a command frequency to an inverter on the basis of voltage/frequency operation; and a slip frequency determination unit for determining a slip frequency on the basis of the phase current and phase voltage of an electric motor driven by the inverter.

An estimation method for estimating a rotor frequency of a motor during freewheeling, includes: applying a fixed input voltage and one selected from a plurality of stator frequencies to the motor sequentially so as to perform frequency scanning; detecting a stator current value of the motor corresponding to the selected stator frequency; calculating a stator current slope of the stator current values sequentially; defining a target period from a start point where the stator current slope varies from positive to negative to an end point where the stator current slope varies from negative to positive; and determining that a difference between the scanned stator frequency and the rotor frequency is within a preset value, then designating any of the corresponding stator frequencies during the target period as an estimated value of the rotor frequency.

An estimation method for estimating a rotor frequency of a motor during freewheeling, includes: applying a fixed input voltage and one selected from a plurality of stator frequencies to the motor sequentially so as to perform frequency scanning; detecting a stator current value of the motor corresponding to the selected stator frequency; calculating a stator current slope of the stator current values sequentially; defining a target period from a start point where the stator current slope varies from positive to negative to an end point where the stator current slope varies from negative to positive; and determining that a difference between the scanned stator frequency and the rotor frequency is within a preset value, then designating any of the corresponding stator frequencies during the target period as an estimated value of the rotor frequency.

An intelligent electronic device (IED) according to the present disclosure can estimate a full load rotor resistance value as a function of motor positive-sequence resistance. The IED may estimate the full load rotor resistance value by measuring zero-crossings of voltage after a motor disconnect. The IED may also acquire motor current and voltage measurements and calculate motor slip using the acquired motor current and voltage measurements and the estimated full load rotor resistance value.

An intelligent electronic device (IED) according to the present disclosure can estimate a full load rotor resistance value as a function of motor positive-sequence resistance. The IED may estimate the full load rotor resistance value by measuring zero-crossings of voltage after a motor disconnect. The IED may also acquire motor current and voltage measurements and calculate motor slip using the acquired motor current and voltage measurements and the estimated full load rotor resistance value.