1.电机T型等效电路模型
1.1 Python代码 - 考虑转差率为负
import numpy as np
import matplotlib.pyplot as plt
# 设置已知参数值
rm = 11.421
lm = 553.9e-3
r2 = 7.553
l2 = 42.90e-3
freq_in = 50
# 设置频率值范围和步长
s = np.linspace(-0.05, 0.05, 1000)
im = 380/(rm+(lm+l2)*2*np.pi*freq_in*1j)/np.sqrt(3);
# 计算并绘制曲线
curr_in = (im + im*(rm+(lm+l2)*2*np.pi*freq_in*1j)/(r2 + l2*2*np.pi*freq_in*1j + (1-s)/s*r2))
plt.plot(np.abs(curr_in), s)
plt.xlabel('Absolute value of curr_in')
plt.ylabel('Power out')
plt.title('s of rated power is 2A, the max Y-axis = 5%(but engine''s rated s = 2%, I think it is wrong.)')
# 绘制横线
horiz_line = plt.axhline(y=0.05, color='r', linestyle='--', label='"s" == rated power of engine')
horiz_line = plt.axhline(y=0, color='r', linestyle='--', label='"s" == 0')
# 添加图例
plt.legend()
plt.show()
1.2 I-s曲线
注意在s = 0附近:
你会发现输出电流最小的位置,并不在转差率 = 0是,而是在转差率达到某个负值的时候——转差率为负,意味着此时电机的负载等效电阻是个负值,在中和掉整个电路的视在等效电阻后,此时的电路转为纯感性电路,此时,电流才会出现极小值,越过这条线,转差率继续向负半周偏移——此时,电机并不是在做功,而是作为一台发电机在工作。就是此时电机正转,但是反拉,提供的力矩与旋转方向相反,克服掉重物的力矩,匀速下滑。
2.不同负载,上下行时的线电流差异
2.1 Python代码
import numpy as np
import matplotlib.pyplot as plt
# 设置已知参数值
rm = 11.421
lm = 553.9e-3
r2 = 7.553
l2 = 42.90e-3
freq_in = 50
im = 380/(rm+(lm+l2)*2*np.pi*freq_in*1j)/np.sqrt(3);
s = np.linspace(0, -0.05, 1000)
curr_in_download = (im + im*(rm+(lm+l2)*2*np.pi*freq_in*1j)/(r2 + l2*2*np.pi*freq_in*1j + (1-s)/s*r2))
# 设置频率值范围和步长
s = np.linspace(0, 0.05, 1000)
# 计算并绘制曲线
curr_in_upword = (im + im*(rm+(lm+l2)*2*np.pi*freq_in*1j)/(r2 + l2*2*np.pi*freq_in*1j + (1-s)/s*r2))
curr_diff_of_updown = curr_in_upword - curr_in_download
plt.plot(np.abs(curr_in_upword), s)
plt.plot(np.abs(curr_diff_of_updown), s)
plt.xlabel('Absolute value of curr_in')
plt.ylabel('Power out')
plt.title('s of rated power is 2A, the max Y-axis = 5%(but engine''s rated s = 2%, I think it is wrong.)')
# 绘制横线
horiz_line = plt.axhline(y=0.05, color='r', linestyle='--', label='"s" == rated power of engine')
horiz_line = plt.axhline(y=0, color='r', linestyle='--', label='"s" == 0')
# 添加图例
plt.legend()
plt.show()
2.2 dI_of(up2down)-s曲线
一个奇迹出现了——转差率和上下行电流差之间呈现出线性关系:(当然,它要考虑到电机的运行方向),此时电流的值是有正负号的。