Inverter control device
AssigneeLs Electric Co., Ltd.
InventorsSeung-Cheol Choi, Hak-Jun Lee
Life of this patent
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Abstract
The present disclosure provides an inverter control device which estimates back electromotive force of an induction motor, and which uses a torque current and a flux current so as to calculate a slip frequency and compensate for same, thereby enabling the motor to operate at a constant speed. To this end, the present invention may comprise: a command voltage generating unit for outputting, to an inverter, a three phase PWM voltage with respect to a command frequency on the basis of a voltage/frequency operation; and a slip frequency determining unit for determining a slip frequency on the basis of a phase current and a phase voltage of a motor driven by the inverter.
Claims8
An inverter control device comprising:
- a command voltage generating unit configured to receive a command frequency and output 3-phases PWM voltage to an inverter, based on voltage/frequency operation;
- and
- a slip frequency determining unit configured to determine a slip frequency based on phase current and phase voltage of a motor driven by the inverter,
- wherein the slip frequency determining unit includes:
- a coordinate converting unit configured to:
- convert the phase current and the phase voltage of the motor to dq-axis phase currents and phase voltages of a stationary coordinate system;
- a disturbance measurement unit configured to:
- estimate a back electromotive force of the motor from the dq-axis currents and voltages;
- and
- estimate a phase angle of the rotor magnetic flux from the back electromotive force of the motor;
- a current estimating unit configured to apply the phase angle of the rotor magnetic flux to the dq-axis phase currents to convert the dq-axis phase currents to a torque-based current and a magnetic flux-based current of the rotation coordinate system;
- and
- a frequency estimating unit configured to output an estimated slip frequency based on the torque-based current, the magnetic flux-based current and a rotor time constant.
Dependencies are inferred from the claim text.