101 lines
2.8 KiB
Python
Executable File
101 lines
2.8 KiB
Python
Executable File
#!/bin/python
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import numpy as np
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import eseries as es
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def calc_fsw_from_r_fset(r_fset):
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fsw = 67600 / (r_fset / 1e3 + 6.4)
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fsw = fsw * 1e3
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return fsw
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def calc_r_fset_from_fsw(fsw):
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fsw = fsw / 1e3
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r = 67600 / (fsw) - 6.4
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r = r * 1e3
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return r
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def calc_r_iset_from_i(i):
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i = i * 1e3
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r = 2000 * 1.2 / i
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r = r * 1e3
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return r
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def calc_i_from_r_iset(r):
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r = r * 1e-3
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i = 2000 * 1.2 / r
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i = i * 1e-3
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return i
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def calc_vout(r1, r2, k):
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r1 = r1 / 1000
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r2 = r2 / 1000
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v = (1.2 / r2 + k * 0.0387) * r1 + 1.2
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return v
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switching_freq = 1.1e6
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output_voltage_nom = 24 + 0.9
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inductor_value = 22e-6
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input_voltage = 12
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output_current_per_lane = 110e-3
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desired_e_series = es.E12
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r1 = 560e3
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r2 = 100e3
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# Calculate the parameters
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print('Calculating for the given parameters:')
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print(f'{switching_freq = }')
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print(f'{output_voltage_nom = } and {input_voltage = }')
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print(f'{inductor_value =}')
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print(f'{desired_e_series = }')
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print('')
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rfset = calc_r_fset_from_fsw(switching_freq)
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print(f'{rfset = }')
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# Find the nearest value in the e series
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rfset = es.find_nearest(desired_e_series, rfset)
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f_sw = calc_fsw_from_r_fset(rfset)
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print(f'The nearest value from the E series is: {rfset = }')
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freq_error = (f_sw - switching_freq) / switching_freq * 100
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print(f'Resulting switching frequency is {f_sw} (Error: {freq_error:.1f} %)')
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print(f"Desired output current per lane is {output_current_per_lane} A")
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r_iset = calc_r_iset_from_i(output_current_per_lane)
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print(f'Resulting in {r_iset = }')
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r_iset = es.find_nearest(desired_e_series, r_iset)
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output_current_per_lane = calc_i_from_r_iset(r_iset)
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print(f'Nearest e series value {r_iset = } resulting in an LED current of {output_current_per_lane} A')
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d = (output_voltage_nom - input_voltage) / output_voltage_nom
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d_inv = 1-d
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print(f"Expected duty cycle: {d}")
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i_ripple = (output_voltage_nom- input_voltage) / (2 * inductor_value * f_sw) * (input_voltage / output_voltage_nom)
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print(f'Ripple current: {i_ripple} A')
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i_sat_min = output_current_per_lane * 4 / d_inv + i_ripple
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print(f'Minimum saturation current of inductor: {i_sat_min:.3f} A')
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print(f'Voltage divider {r1 = } | {r2 = }')
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print(f'Output voltage initial: {calc_vout(r1, r2, 0.88)} V')
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print(f'Output voltage maximum: {calc_vout(r1, r2, 1)} V')
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print(f'Output voltage minimum: {calc_vout(r1, r2, 0)} V')
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ovp = output_voltage_nom + (r1/r2 + 1)*(2.3 - 1.2)
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print(f'Over voltage protection: {ovp} V')
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ratio = r1/r2
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print(f'Resistance ratio is {ratio}')
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if f_sw <= 1150e3:
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ratio_range = (5, 10)
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else:
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ratio_range = (10, 20)
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if ratio < ratio_range[0] or ratio > ratio_range[1]:
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print('Ratio is outside recommended limits!')
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else:
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print('Resistance ratio is inside recommended limits')
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# Loop stability
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cfb = 1 / (2 * np.pi * 20e3 * r1 )
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print(f'Loop stability capacitor value: {cfb} F')
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