Patent ID: 6184638
Filing Date: 2001-02-06
Classification: H02P

Abstract:
A control system for an induction motor comprising:current detecting means for detecting a primary current of an induction motor;excitation-current command computing means for receiving a secondary magnetic flux command to be output by the induction motor, and processing an AC signal and a DC signal proportional to said secondary magnetic flux command, to thereby produce an excitation current command of the induction motor;torque control means for receiving a torque command to be output by the induction motor and said excitation current command, and processing said estimated rotation angular velocity, said estimated secondary resistance and said primary current, and said torque control means controlling a primary voltage of the induction motor so that an output torque of the induction motor follows said torque command;first parameter estimating means for processing estimated primary resistance, said primary voltage and said primary current of the induction motor, to thereby produce said estimated rotation angular velocity and said estimated secondary resistance; andsecond parameter estimating means for processing said estimated rotation angular velocity, said estimated secondary resistance, said primary voltage and said primary current, to thereby produce said estimated primary resistance,whereinsaid first parameter estimating means includesa) a first measuring unit for processing said estimated primary resistance, said estimated secondary resistance, said estimated rotation angular velocity, a first feedback gain, said primary voltage and said primary current, to thereby produce estimated secondary current, estimated secondary magnetic flux and first state deviation,b) a rotational-speed estimating unit for processing said first state deviation and said estimated secondary magnetic flux, which are derived from said first measuring unit, to thereby produce said estimated rotation angular velocity,c) a secondary-resistance estimating unit for processing said first state deviation and said estimated secondary current, which are derived from said first measuring unit, to thereby produce said estimated secondary resistance, andd) a first gain computing unit for processing said estimated rotation angular velocity derived from said rotational-speed estimating unit, to thereby produce said first feedback gain so that said first state deviation contains a component orthogonal to said estimated secondary magnetic flux, andsaid second parameter estimating unit includesa) a second measuring unit for processing said estimated primary resistance, said secondary resistance, said estimated rotation angular velocity, a second feedback gain, said primary voltage, and said primary current, to thereby produce an estimated primary current and a second state deviation,b) a primary-resistance estimating unit for processing said second state deviation and said estimated primary current, thereby produce said estimated primary resistance, andc) a second gain computing unit for processing said rotation angular velocity derived from said rotational-speed estimating unit, to thereby produce said second state deviation so that said first state deviation contains a component being in phase with said estimated primary current.