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AssigneeHitachi, Ltd.
InventorsKeijiro Sakai, Tsunehiro Endo, Toshiaki Okuyama, Hiroshi Fujii
Estimating the term…
An inverter corrects an output voltage in accordance with the magnitude of output voltage error due to a dead time and an ON-state voltage drop in power elements so as to energize an AC motor in a manner of single phase alternating current excitation, by calculating an active component of current Iq and a reactive component of current Id from the phase .theta. of an excitation voltage vector and a detected instantaneous current value iu, and by measuring characteristic constants of the motor, including a combined resistance (r.sub.1 +r.sub.2) and a combined leakage inductance (l.sub.1 +l.sub.2), from an excitation voltage command value Vc.sub.1, Id and Iq. The measured values are used as the control constants for a speed sensorless vector control. Further, the resistances r.sub.1, r.sub.2, and a self-inductance L.sub.1, which are control constants, can be obtained based on the component in a primary voltage vector direction of a primary current vector Iq' and the component .pi./2 delayed from the primary voltage vector direction of the primary current vector Id'. In this way, the characteristic constants can be accurately measured without any inverter output voltage sensor.
A method of measuring characteristic constants of a three-phase alternating current motor controlled by an inverter apparatus including a three-phase inverter for converting a direct current voltage into a three-phase alternating current so as to supply the three-phase alternating current to said three-phase motor and a controller for controlling the magnitude and pulse-width of an output voltage of said three-phase inverter, the method comprising the steps of:
A controller for controlling a three-phase alternating current motor using an inverter apparatus comprising:
Dependencies are inferred from the claim text.