System and method to determine electric motor efficiency using an equivalent circuit
AssigneeEaton Corporation
InventorsBin Lu, Thomas G. Habetler
Life of this patent
Estimating the term…
Abstract
A system and method for determining electric motor efficiency includes a monitoring system having a processor programmed to determine efficiency of an electric motor under load while the electric motor is online. The determination of motor efficiency is independent of a rotor speed measurement. Further, the efficiency is based on a determination of stator winding resistance, an input voltage, and an input current. The determination of the stator winding resistance occurs while the electric motor under load is online.
Claims19
A non-transitory computer readable storage medium having stored thereon a computer program comprising instructions, which when executed by a computer, cause the computer to:
- determine an input voltage and current at a first operating point of an online induction motor;
- determine an input voltage and current at a second operating point of the online induction motor;
- determine at least one modified equivalent circuit based on voltage and current phasors corresponding to the input voltages and currents at the first and second load points;
- calculate a plurality of motor parameters from the at least one modified equivalent circuit;
- and
- determine a motor efficiency of the online induction motor based on the plurality of calculated motor parameters.
A method for determining efficiency of an induction motor, the method comprising:
- determining a voltage and current input into a stator of an induction motor during operation thereof at each of at least two motor operating points, wherein each motor operating point comprises a distinct percentage of a maximum rated operating load;
- determining voltage and current phasors associated with the voltage and current inputs;
- determining an equivalent circuit based on the voltage and current phasors;
- determining a plurality of independent equations based upon the equivalent circuit, the plurality of independent equations having a set of motor parameters associated therewith;
- and
- solving the plurality of independent equations for the set of motor parameters to determine a motor efficiency of the induction motor.
A non-transitory computer readable storage medium having stored thereon a computer program comprising instructions, which when executed by a computer, cause the computer to:
- determine an input voltage and current at each of a first operating point and a second operating point of an online induction motor, wherein each of the first and second operating points comprises a distinct percentage of a maximum rated operating load;
- determine voltage and current phasors associated with the voltage and current inputs;
- determine an equivalent circuit based on the voltage and current phasors;
- determine four independent equations from the one equivalent circuit, the independent equations having a set of motor parameters associated therewith;
- calculate a plurality of motor parameters from the at least one modified equivalent circuit;
- and
- determine a motor efficiency of the online induction motor based on the plurality of calculated motor parameters.
Dependencies are inferred from the claim text.