METHOD FOR DETERMINING PARAMETER VALUES OF AN INDUCTION MACHINE BY MEANS OF POLYNOMINAL CALCULATIONS

• US 20170075861A1
• Filed: 12/01/2015
• Published: 03/16/2017
• Est. Priority Date: 09/14/2015
• Status: Active Grant

• Current Assignee: I-Shou University
• Original Assignee: I-Shou University
• Inventors: WU, Rong-Ching
• Granted Patent: US 9,740,664 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 17/11 for solving equations , e.g. nonlinear equations, general mathematical optimization problems optimization specially adapted for a specific administrative, business or logistic context G06Q10/04
• CPC Class Codes: G06F 17/156 using a domain transform, e.g. Fourier transform, polynomial transform, number theoretic transform
• CPC Class Codes: G06F 30/36 Circuit design at the analogue level

Abstract

A method for determining parameter values of an induction machine. The method may be executed by a dedicated computer system. The method includes sampling a voltage signal, a current signal and a rotational speed signal of the induction machine at the time the induction machine is started, calculating a resistance and a reactance of the induction machine at each of a plurality of slip rates according to the voltage signal and the current signal, calculating a plurality of coefficients of a polynomial fraction based on the resistances and the reactances, calculating the parameter values of an equivalent circuit according to the plurality of coefficients of the polynomial fraction, calculating a moment of inertia and a friction coefficient of the induction machine according to the calculated parameter values and the rotational speed signal of the equivalent circuit, and outputting the moment of inertia and the friction coefficient of the induction machine.

Claims

1. A method for determining parameter values of an induction machine by means of polynomial calculations, as performed by a dedicated computer system, comprising:

sampling a voltage signal, a current signal and a rotational speed signal of the induction machine at the time the induction machine is started;

calculating a resistance and a reactance of the induction machine at each of a plurality of slip rates according to the voltage signal and the current signal;

calculating a plurality of coefficients of a polynomial fraction based on the resistances and the reactances;

calculating parameter values of an equivalent circuit according to the plurality of coefficients of the polynomial fraction;

calculating a moment of inertia and a friction coefficient of the induction machine according to the calculated parameter values and the rotational speed signal of the equivalent circuit; and

outputting the moment of inertia and the friction coefficient of the induction machine.

2. The method for determining the parameter values of the induction machine by means of polynomial calculations as claimed in claim 1, wherein the equivalent circuit comprises a stator resistance, a stator reactance and a magnetizing reactance that are connected in series to form an open loop, and wherein the equivalent circuit further comprises a rotor reactance and a rotor resistance that are connected to two ends of the magnetizing reactance to form a closed loop.

3. The method for determining the parameter values of the induction machine by means of polynomial calculations as claimed in claim 2, wherein the polynomial fraction is expressed as:

4. The method for determining the parameter values of the induction machine by means of polynomial calculations as claimed in claim 3, wherein the magnetizing reactance, the rotor reactance and the stator reactance have a predetermined ratio η

below;

5. The method for determining the parameter values of the induction machine by means of polynomial calculations as claimed in claim 4, wherein the predetermined ratio is between 0.95 and 1.05.

6. The method for determining the parameter values of the induction machine by means of polynomial calculations as claimed in claim 4, wherein the magnetizing reactance is expressed as:

7. The method for determining the parameter values of the induction machine by means of polynomial calculations as claimed in claim 4, wherein the stator reactance is expressed as:

X_S=β

₃−

X_m.

8. The method for determining the parameter values of the induction machine by means of polynomial calculations as claimed in claim 4, wherein the rotor reactance is expressed as:

X_r=η

(X_m+X_S)−

X_m=η

β

₃−

X_m.

9. The method for determining the parameter values of the induction machine by means of polynomial calculations as claimed in claim 4, wherein the rotor resistance is expressed as:

R_r=X_m²/β

₁.

10. The method for determining the parameter values of the induction machine by means of polynomial calculations as claimed in claim 4, wherein the stator resistance is expressed as:

11. The method for determining the parameter values of the induction machine by means of polynomial calculations as claimed in claim 1, wherein the moment of inertia and the friction coefficient are expressed as: