Parameter Estimation of Permanent-Split Capacitor-Run Single-Phase Induction Motor Using Computed Complex Voltage Ratio

Equivalent circuit parameters and performance variables of permanent-split capacitor-run single-phase induction motor can be obtained from dc test, no-load test, locked-rotor test, and using turns ratio as derived from the winding ratio test (the last one is carried out if the design data are not available). In this paper, turns ratio has been replaced by a computed complex voltage ratio, based on an assumption that single-phase motor for parameter transformation can be represented as an ideal transformer. The equations for this complex quantity have been derived that provide an alternative to winding ratio test, which otherwise requires the tedium of a physical test on the motor. The performance variables like input current, power factor, and power consumed by the motor, obtained by the proposed technique, have been compared with those obtained using the conventional techniques as well as with the experimental observations obtained on three fan motors of different ratings. It is observed that the proposed method gives performance variable values closer to the experimental observations in comparison to those obtained using the conventional methods.

I. Nomenclature

, ,

Locked-rotor power, current, and voltage.

, ,

Locked-rotor resistance, reactance, and impedance.

,

DC resistance of main and auxiliary winding.

,

Stator resistance and reactance.

,

Rotor resistance and reactance.

, ,

No-load power, current, and voltage.

,

Voltage across magnetizing reactance at no-load, assuming main and auxiliary winding (each separately) as running winding.

,

Main winding reactance and magnetizing reactance.

,

Number of poles and frequency (in hertz).

,

Synchronous and actual speed.

,

Forward and backward slip.

,

Effective impedance of forward and backward branch of main winding.

,

Effective impedance of forward and backward branch of auxiliary winding.

,

Stator main and auxiliary winding impedance.

,

Total input impedance of stator main and auxiliary winding.

,

Auxiliary winding reactance and magnetizing reactance.

, , ,

Resistance, capacitance, reactance, and impedance of nonideal capacitor.

,

Line voltage applied to main and auxiliary winding.

Voltage measured across the auxiliary winding when only main winding is energized with applied voltage .

Voltage measured across the main winding when only auxiliary winding is energized with applied voltage .

Main winding self-induced electromotive force (EMF), computed at rated voltage.

Auxiliary winding self-induced EMF, computed at rated voltage.

Turns ratio.

Computed complex voltage ratio (CCVR).

,

Computed phasor current of main and auxiliary winding at rated voltage (considering each separately).

,

Induced EMF in main winding by its forward and backward revolving magnetic field.

,

Induced EMF in auxiliary winding by its forward and backward revolving magnetic field.

,

Induced EMF in main winding by forward and backward revolving field of auxiliary winding.

,

Induced EMF in auxiliary winding by forward and backward revolving field of main winding.

,

Current in main and auxiliary winding, when both windings are in operation.

, , ,

Rated voltage, line current, input power, and power factor.