Initial commit

README.md

@@ -0,0 +1,11 @@
+Moto: Induction motor parameter estimation tool
+===============================================
+Current version: 0.1 Beta
+
+Minimum requirements
+- Python 2.7
+- PyQt
+- Numpy
+- Matplotlib
+	- Dateutil
+	- Pyparsing

common_calcs.py

@@ -0,0 +1,110 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+"""
+Moto: Induction motor parameter estimation tool
+
+Common Calculations Module
+
+Author: Julius Susanto
+Last edited: January 2014
+"""
+import numpy as np
+
+"""
+GET_TORQUE - Calculate double cage motor torque and stator current (without core loss component)
+ 
+Usage: get_torque (slip,type,x)
+
+Where slip is the motor slip (pu)
+       x is a vector of motor equivalent parameters:
+           x = [Rs Xs Xm Rr1 Xr1 Rr2 Xr2]
+            Rs = stator resistance
+            Rs = stator reactance
+            Xm = magnetising reactance
+            Rr1 = rotor / inner cage resistance
+            Xr1 = rotor / inner cage reactance
+            Rr2 = outer cage resistance
+            Xr2 = outer cage reactance       
+             
+Returns: motor torque (pu) as a real number and stator current (as a
+complex number and without core loss component)
+"""    
+def get_torque(slip, x):
+
+    # Calculate admittances
+    Ys = 1 / np.complex(x[0], x[1])
+    Ym = 1 / np.complex(0, x[2])
+    Yr1 = 1 / np.complex(x[3] / slip, x[4])
+    Yr2 = 1 / np.complex(x[5] / slip, x[6])
+
+    # Calculate voltage and currents
+    u1 = Ys / (Ys + Ym + Yr1 + Yr2)
+    ir1 = np.abs (u1 * Yr1)
+    ir2 = np.abs (u1 * Yr2)
+
+    # Calculate torque and stator current
+    torque = x[3] / slip * (ir1 ** 2) + x[5] / slip * (ir2 ** 2);
+    ist = (1 - u1) * Ys
+
+    return torque, ist
+
+"""
+CALC_PQT - Calculates motor mechanical power, reactive power, breakdown
+torque and efficiency from equivalent circuit parameters (used for double
+cage model with core losses)
+
+Usage: calc_pqt (sf,x)
+
+Where sf is the full load slip (pu)
+       x is a 8 x 1 vector of motor equivalent parameters:
+           x = [Rs Xs Xm Rr1 Xr1 Rr2 Xr2 Rc]
+            x(0) = Rs = stator resistance
+            x(1) = Xs = stator reactance
+            x(2) = Xm = magnetising reactance
+            x(3) = Rr1 = rotor / inner cage resistance
+            x(4) = Xr1 = rotor / inner cage reactance
+            x(5) = Rr2 = outer cage resistance
+            x(6) = Xr2 = outer cage reactance
+            x(7) = Rc = core resistance
+              
+Returns: y is a vector [Pm Q Tb I_nl]
+"""
+def calc_pqt(sf, x):
+
+    x = np.abs(x)
+
+    # Calculate full-load torque and current
+    [T_fl, i_s] = get_torque(sf,x)
+
+    # Calculate mechanical power (at FL)
+    Pm = T_fl * (1 - sf)                               
+    Sn = np.complex(1,0) * np.conj(i_s)
+
+    # Calculate reactive power input (at FL)
+    Q_fl = np.abs(np.imag(Sn)) 
+
+    # Calculate core loss currents (at FL)
+    i_c = 1 / np.complex (x[7],0)
+
+    # Calculate total input current (at FL)    
+    i_in = i_s + i_c
+
+    # Calculate input power (at FL)
+    p_in = np.real(np.complex(1,0) * np.conj(i_in))
+
+    # Calculate efficiency (at FL)
+    eff_fl = Pm / p_in                                 
+
+    # Calculate breakdown torque with an interval search
+    T_b = 0
+    for n in range(1,101):
+        i = float(n) / 100
+        [T_i, I_i] = get_torque(i,x)                                
+        if T_i > T_b:
+            T_b = T_i           # Calculated breakdown torque
+
+    [T_lr, i_lr] = get_torque(1,x);
+    y = [Pm, Q_fl, T_b, T_lr, np.abs(i_lr + i_c), eff_fl]
+
+    return y