python pyqt matplotlib计算GUI应用程序绘制错误

Jiabin Shen 发表于 Dev

Jiabin Shen

每个人！我正在使用python pyqt4设计用于计算PV面板的VI曲线的GUI的项目。我想输入所需的参数并计算PV面板的输出电流，并使用matplotlib绘制VI曲线。我的代码运行良好。但是，我发现从应用程序获得的曲线是错误的，而直接计算它是正确的。计算方法完全相同。但是当我把计算放在GUI上时是不同的。代码在这里：

import sys
from PyQt4 import QtGui
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.backends.backend_qt4agg import NavigationToolbar2QT as NavigationToolbar
import matplotlib.pyplot as plt
import numpy as np
from scipy.optimize import fsolve
q = 1.6 * (10 ** -19)
k = 1.38 * (10 ** -23)
Tref = 25
Eg = 1.1

def calReverseSaturationCurrent(Isc,Voc,Ns,A,Tc):
    a = np.exp(q*Voc/(Ns*k*A*Tc))-1
    return Isc/a
def calSaturationCurrent(Irs,Tc,A):
    return Irs*((Tc/Tref)**3)*np.exp(q*Eg*(1/Tref - 1/Tc)/(k*A))
def calPhotocurrent(Isc,Ki,Tc,insolation):
    return (Isc + Ki*(Tc-Tref))*insolation
def calOutputCurrent(Isc,Voc,Ns,A,Tc,Ki,insolation,Np,Rs,Rsh,V):
    Irs = calReverseSaturationCurrent(Isc,Voc,Ns,A,Tc)
    Is = calSaturationCurrent(Irs,Tc,A)
    Iph = calPhotocurrent(Isc,Ki,Tc,insolation)
    I0 = 0
    I = np.array([])
    def f(ii,*arg):
        temp_v = arg[0]
        return ii - Np*Iph+Np*Is*(np.exp(q*(temp_v/Ns+ii*Rs/Np)/(k*Tc*A))-1)
    for vv in V:
        ii=fsolve(f,I0,args=vv)
        I = np.append(I,ii)
    return I
class Example(QtGui.QWidget):

    def __init__(self):
        super(Example, self).__init__()

        self.initUI()
    def initUI(self):

        self.figure = plt.figure()
        self.canvas = FigureCanvas(self.figure)

        self.toolbar = NavigationToolbar(self.canvas, self)
        self.toolbar.hide()

        self.idealFactor = QtGui.QLabel('Ideal Factor A')
        self.shortCircuitCurrent = QtGui.QLabel('Short Circuit Current')
        self.openCircuitVoltage = QtGui.QLabel('Open Circuit Voltage')
        self.temperatureCoefficient = QtGui.QLabel('Temperature Coefficient')
        self.seriesCells = QtGui.QLabel('Series Cells')
        self.parallelCells = QtGui.QLabel('Parallel Cells')
        self.seriesResistance = QtGui.QLabel('Series Resistance')
        self.shuntResistance = QtGui.QLabel('Shunt Resistance')
        self.outputVoltageMin = QtGui.QLabel('Min Output Voltage')
        self.outputVoltageMax = QtGui.QLabel('Max Output Voltage')
        self.workingTemperature = QtGui.QLabel('Working Temperature')
        self.isolation = QtGui.QLabel('Isolation')

        self.idealFactorEdit = QtGui.QDoubleSpinBox()
        self.idealFactorEdit.setValue(1.0)
        self.shortCircuitCurrentEdit = QtGui.QDoubleSpinBox()
        self.shortCircuitCurrentEdit.setValue(3.17)
        self.openCircuitVoltageEdit = QtGui.QDoubleSpinBox()
        self.openCircuitVoltageEdit.setValue(21.8)
        self.temperatureCoefficientEdit = QtGui.QDoubleSpinBox()
        self.temperatureCoefficientEdit.setValue(0.065)
        self.seriesCellsEdit = QtGui.QDoubleSpinBox()
        self.seriesCellsEdit.setValue(36.0)
        self.parallelCellsEdit = QtGui.QDoubleSpinBox()
        self.parallelCellsEdit.setValue(1.0)
        self.seriesResistanceEdit = QtGui.QDoubleSpinBox()
        self.seriesResistanceEdit.setValue(0.1)
        self.shuntResistanceEdit = QtGui.QDoubleSpinBox()
        self.shuntResistanceEdit.setValue(float("inf"))
        self.outputVoltageMinEdit = QtGui.QDoubleSpinBox()
        self.outputVoltageMinEdit.setValue(8)
        self.outputVoltageMaxEdit = QtGui.QDoubleSpinBox()
        self.outputVoltageMaxEdit.setValue(11)
        self.workingTemperatureEdit = QtGui.QDoubleSpinBox()
        self.workingTemperatureEdit.setValue(25)
        self.isolationEdit = QtGui.QDoubleSpinBox()
        self.isolationEdit.setValue(1)

        self.calBtn = QtGui.QPushButton('Get V-I',self)
        self.calBtn.clicked.connect(self.getVI)

        grid = QtGui.QGridLayout()
        self.setLayout(grid)

        grid.addWidget(self.idealFactor, 1, 0)
        grid.addWidget(self.idealFactorEdit, 1, 1)

        grid.addWidget(self.shortCircuitCurrent, 1, 2)
        grid.addWidget(self.shortCircuitCurrentEdit, 1, 3)

        grid.addWidget(self.openCircuitVoltage, 2, 0)
        grid.addWidget(self.openCircuitVoltageEdit, 2, 1)

        grid.addWidget(self.temperatureCoefficient, 2, 2)
        grid.addWidget(self.temperatureCoefficientEdit, 2, 3)

        grid.addWidget(self.seriesCells, 3, 0)
        grid.addWidget(self.seriesCellsEdit, 3, 1)

        grid.addWidget(self.parallelCells, 3, 2)
        grid.addWidget(self.parallelCellsEdit, 3, 3)

        grid.addWidget(self.seriesResistance, 4, 0)
        grid.addWidget(self.seriesResistanceEdit, 4, 1)

        grid.addWidget(self.shuntResistance, 4, 2)
        grid.addWidget(self.shuntResistanceEdit, 4, 3)

        grid.addWidget(self.outputVoltageMax, 5, 0)
        grid.addWidget(self.outputVoltageMaxEdit, 5, 1)

        grid.addWidget(self.outputVoltageMin, 5, 2)
        grid.addWidget(self.outputVoltageMinEdit, 5, 3)

        grid.addWidget(self.workingTemperature, 6, 0)
        grid.addWidget(self.workingTemperatureEdit, 6, 1)

        grid.addWidget(self.isolation, 6, 2)
        grid.addWidget(self.isolationEdit, 6, 3)

        grid.addWidget(self.calBtn, 7,0)
        grid.addWidget(self.canvas, 8, 0, 6, 0)


        self.setGeometry(300, 300, 1000, 800)
        self.setWindowTitle('PYPV')
        self.setWindowIcon(QtGui.QIcon('pvPanel.png'))        

        self.show()

    def getVI(self):
        A = self.idealFactorEdit.value()
        Isc = self.shortCircuitCurrentEdit.value()
        Voc = self.openCircuitVoltageEdit.value()
        Ki = self.temperatureCoefficientEdit.value()
        Ns = self.seriesCellsEdit.value()
        Np = self.parallelCellsEdit.value()
        Rs = self.seriesResistanceEdit.value()
        Rsh = self.shuntResistanceEdit.value()
        Vmin = self.outputVoltageMinEdit.value()
        Vmax = self.outputVoltageMaxEdit.value()
        V = np.linspace(Vmin,Vmax,1000)
        Tc = self.workingTemperatureEdit.value()
        insolation = self.isolationEdit.value()
        I = calOutputCurrent(Isc,Voc,Ns,A,Tc,Ki,insolation,Np,Rs,Rsh,V)
        plt.cla()
        ax = self.figure.add_subplot(111)
        ax.plot(V,I)
        self.canvas.draw()


def main():

    app = QtGui.QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

我确定计算方法是正确的。我没有使用GUI进行测试。结果很好。代码如下：

import numpy as np
from scipy.optimize import fsolve
from matplotlib import pyplot as plt

q = 1.6 * (10 ** -19)
k = 1.38 * (10 ** -23)
Tref = 25
Eg = 1.1
A = 1.0
V = np.linspace(8,11,1000)
Isc = 3.17
Ki = 0.07
Ns = 36.0
Np = 1.0
Voc = 21.8
Rs = 0.1
#Rsh = float("inf")
Tc = 25
insolation = 1

def calReverseSaturationCurrent(Isc,Voc,Ns,A,Tc):
    a = np.exp(q*Voc/(Ns*k*A*Tc))-1
    return Isc/a

def calSaturationCurrent(Irs,Tc,A):
    return Irs*((Tc/Tref)**3)*np.exp(q*Eg*(1/Tref - 1/Tc)/(k*A))

def calPhotocurrent(Isc,Ki,Tc,insolation):
    return (Isc + Ki*(Tc-Tref))*insolation

def calOutputCurrent(Isc,Voc,Ns,A,Tc,Ki,insolation,Np,Rs,Rsh,V):
    Irs = calReverseSaturationCurrent(Isc,Voc,Ns,A,Tc)
    Is = calSaturationCurrent(Irs,Tc,A)
    Iph = calPhotocurrent(Isc,Ki,Tc,insolation)
    I0 = 0
    I = np.array([])
    def f(ii,*arg):
        temp_v = arg[0]
        return ii - Np*Iph+Np*Is*(np.exp(q*(temp_v/Ns+ii*Rs/Np)/(k*Tc*A))-1)
    for vv in V:
        ii=fsolve(f,I0,args=vv)
        I = np.append(I,ii)
    return I

def makePlots(I,V):
    plt.plot(V,I)
    plt.show()

def test():
    I = calOutputCurrent(Isc,Voc,Ns,A,Tc,Ki,insolation,Np,Rs,Rsh,V)
    makePlots(I,V)

if __name__ == "__main__":
    test()

下面是两个图：不使用GUI 和GUI

英语不是我的母语。我希望我能很好地描述问题。提前致谢！

titusjan

我的猜测是您使用的是Python-2，该/运算符对整数的行为不同于对浮点数的行为。在第一种情况下，它是整数除法：结果是整数，其余部分被舍弃。在第二种情况下，这通常是您期望除法的结果。这是许多错误的根源，因此在Python-3中，/运算符始终是常规除法（返回浮点数），并且可以使用进行整数除法//。有关更多详细信息，请参阅PEP-238。请注意，您的calSaturationCurrent函数包含这样的整数除法：1/Tc在Python-2中产生0。

为了使Python-2的行为像Python 3一样，您可以使用“未来导入”。如果在程序的顶部（在其他导入语句之前）添加以下行，则无论有没有GUI，都将得到相同的结果。

from __future__ import division

现在，您可能还为非GUI版本使用了Python-2，那么为什么首先要获得不同的结果？我最好的猜测是，在程序的gui版本中，从Qt获得的值略有不同（远远落后于小数点）。您的程序容易受此影响的事实表明它可能存在错误。

例如，如果打印该calSaturationCurrent函数的结果，则不带GUI时为3.42723507299e-122，带GUI时为0.0。这意味着f您要求解其根的函数始终非常接近0或正好为0。我不相信结果，而是从对f自身进行绘制开始。

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编辑于2021-03-1

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