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Author: Harald Schilly
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Compute Environment: Ubuntu 20.04 (Experimental)
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import numpy as np import matplotlib.pyplot as plt import PySpice.Logging.Logging as Logging logger = Logging.setup_logging() from PySpice.Probe.Plot import plot from PySpice.Spice.Netlist import Circuit from PySpice.Unit import * from scipy.optimize import curve_fit
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figure, (ax1, ax2) = plt.subplots(2, figsize=(20, 10)) element_types = ('capacitor', 'inductor') for element_type in ('capacitor', 'inductor'): circuit = Circuit(element_type.title()) # Fixme: compute value source = circuit.PulseVoltageSource('input', 'in', circuit.gnd, initial_value=0 @ u_V, pulsed_value=10 @ u_V, pulse_width=10 @ u_ms, period=20 @ u_ms) circuit.R(1, 'in', 'out', 1 @ u_kΩ) if element_type == 'capacitor': element = circuit.C value = 1 @ u_uF # tau = RC = 1 ms else: element = circuit.L # Fixme: force component value to an Unit instance ? value = 1 @ u_H # tau = L/R = 1 ms element(1, 'out', circuit.gnd, value) # circuit.R(2, 'out', circuit.gnd, kilo(1)) # for debug if element_type == 'capacitor': tau = circuit['R1'].resistance * circuit['C1'].capacitance else: tau = circuit['L1'].inductance / circuit['R1'].resistance simulator = circuit.simulator(temperature=25, nominal_temperature=25) step_time = 10 @ u_us analysis = simulator.transient(step_time=step_time, end_time=source.period * 3) # Let define the theoretical output voltage. if element_type == 'capacitor': def out_voltage(t, tau): # Fixme: TypeError: only length-1 arrays can be converted to Python scalars return float(source.pulsed_value) * (1 - np.exp(-t / tau)) else: def out_voltage(t, tau): return float(source.pulsed_value) * np.exp(-t / tau) # Fixme: get step_time from analysis # At t = 5 tau, each circuit has nearly reached it steady state. i_max = int(5 * tau / float(step_time)) popt, pcov = curve_fit(out_voltage, analysis.out.abscissa[:i_max], analysis.out[:i_max]) tau_measured = popt[0] # Fixme: use Unit().canonise() print('tau {0} = {1}'.format(element_type, tau.canonise().str_space())) print('tau measured {0} = {1:.1f} ms'.format(element_type, tau_measured * 1000)) if element_type == 'capacitor': ax = ax1 title = "Capacitor: voltage is constant" else: ax = ax2 title = "Inductor: current is constant" ax.set_title(title) ax.grid() current_scale = 1000 ax.plot(analysis['in']) ax.plot(analysis['out']) # Fixme: resistor current, scale ax.plot(((analysis['in'] - analysis.out) / circuit['R1'].resistance) * current_scale) ax.axvline(x=float(tau), color='red') ax.set_ylim(-11, 11) ax.set_xlabel('t [s]') ax.set_ylabel('[V]') ax.legend(('Vin [V]', 'Vout [V]', 'I'), loc=(.8, .8)) plt.tight_layout() plt.show()
2020-10-10 08:36:44,029 - PySpice.Spice.Netlist.Node.__init__ - WARNING - Node name 'in' is a Python keyword tau capacitor = 1.0 ms tau measured capacitor = 1.0 ms 2020-10-10 08:36:44,195 - PySpice.Spice.Netlist.Node.__init__ - WARNING - Node name 'in' is a Python keyword tau inductor = 1.0 ms tau measured inductor = 1.0 ms
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