Method for measuring motor parameters of induction motor and control apparatus

A control apparatus for an induction motor, comprising:

• a driver having a variable output voltage and frequency;
• a motor parameter measurement system for measuring motor parameters of the induction motor driven by the driver;
• a slip frequency operator for deriving a slip frequency from a rotor resistance and inductance of the induction motor, an excitation current command, and a torque current command;
• an induction motor current command output means for deriving a current to flow in the induction motor, from the torque current command, the excitation current command, a detected or estimated rotational speed of the induction motor, and the slip frequency, so as to output a current command;
• and
• a current controller for comparing the induction motor current command and a detected current of the induction motor to output a voltage command according to a compared result;
• wherein the motor parameter measurement system outputs a current command having a frequency of a predetermined value or more and a current waveform of a triangular wave for setting the induction motor to be in a single-phase feed state, the current controller provides the driver with a voltage command to follow the current command, and the motor parameter measurement system solves two equations obtained from detected or commanded voltage values and detected motor current values at two different times and a current differential value to find a sum of a stator resistance value and a rotor resistance value of a T-I type equivalent circuit of the induction motor, and finds the rotor resistance value from a difference between the sum of the stator resistance value and the rotor resistance value and the known stator resistance value, the stator resistance value and the rotor resistance value being used for a slip frequency operation by the slip frequency operator and a speed estimation by a speed estimator.

A control apparatus for an induction motor, comprising:

• a driver having a variable output voltage and frequency;
• a motor parameter measurement system for measuring motor parameters of the induction motor driven by the driver;
• a slip frequency operator for deriving a slip frequency from a rotor resistance and inductance of the induction motor, an excitation current command, and a torque current command;
• an induction motor current command output means for deriving a current to flow in the induction motor, from the torque current command, the excitation current command, a detected or estimated rotational speed of the induction motor, and the slip frequency, so as to output a current command;
• and
• a current controller for comparing the induction motor current command and a detected current of the induction motor to output a voltage command according to a compared result;
• wherein the motor parameter measurement system outputs a current command having a frequency of a predetermined value or more and a current waveform of a triangular wave for setting the induction motor to be in a single-phase feed state, the current controller provides the driver with a voltage command to follow the current command, and the motor parameter measurement system solves two equations obtained from detected or commanded voltage values and detected motor current values at two different times and a current differential value to find a leakage inductance value of a T-I type equivalent circuit of the induction motor, the leakage inductance value being used for a slip frequency operation by the slip frequency operator and a speed estimation by a speed estimator.

A control apparatus for an induction motor, comprising:

• a driver having a variable output voltage and frequency;
• a motor parameter measurement system for measuring motor parameters of the induction motor driven by the driver;
• a slip frequency operator for deriving a slip frequency from a rotor resistance and inductance of the induction motor, an excitation current command, and a torque current command;
• an induction motor current command output means for deriving a current to flow in the induction motor, from the torque current command, the excitation current command, a detected or estimated rotational speed of the induction motor, and the slip frequency, so as to output a current command;
• and
• a current controller for comparing the induction motor current command and a detected current of the induction motor to output a voltage command according to a compared result;
• wherein the motor parameter measurement system outputs a sine wave current command having a predetermined angular frequency .omega..sub.1 for setting the induction motor to be in a single-phase feed state, the current controller provides the driver with a voltage command to follow the current command, and the motor parameter measurement system solves the following equation to find a mutual inductance value M', a leakage inductance value being used for a slip frequency operation by the slip frequency operator and a speed estimation by a speed estimator, ##EQU24## where V.sub.1 represents a detected or commanded voltage value, I.sub.1 represents a detected motor current value, Z represents a ratio of the voltage to the motor current .vertline.V.sub.1 .vertline./.vertline.I.sub.1 .vertline., R.sub.1, R.sub.2 ', and L.sigma. represent a known stator resistance value, a rotor resistance value, and a leakage inductance value of a T-I type equivalent circuit of an induction motor, respectively.

A control apparatus for an induction motor, comprising:

• a driver having a variable output voltage and frequency;
• a motor parameter measurement system for measuring motor parameters of the induction motor driven by the driver;
• a slip frequency operator for deriving a slip frequency from a rotor resistance and inductance of the induction motor, an excitation current command, and a torque current command;
• an induction motor current command output means for deriving a current to flow in the induction motor, from the torque current command, the excitation current command, a detected or estimated rotational speed of the induction motor, and the slip frequency, so as to output a current command;
• and
• a current controller for comparing the induction motor current command and a detected current of the induction motor to output a voltage command according to a compared result;
• wherein the motor parameter measurement system outputs a sine wave current command having a predetermined angular frequency .omega..sub.1 for setting the induction motor to be in a single-phase feed state, the current controller provides the driver with a voltage command to follow the current command, and the motor parameter measurement system solves the following equation to find a mutual inductance value M', a leakage inductance value being used for a slip frequency operation by the slip frequency operator and a speed estimation by a speed estimator, ##EQU26## where V.sub.1 represents a detected or commanded voltage value, I.sub.1 represents a detected motor current value, Z represents a ratio of the voltage to the motor current .vertline.V.sub.1 .vertline./.vertline.I.sub.1 .vertline., and R.sub.1, R.sub.2 ', and L.sigma. represent a known stator resistance value, a rotor resistance value, and a leakage inductance value of a T-I type equivalent circuit of an induction motor, respectively.