Python script to measure DC-DC converters

[tszaboo]

I've made a python script to measure DC-DC converters.
It measures the efficiency across input voltage and load current
And shows the load dependency of the output voltage.
I've included an example output of a very simple 7812 based power supply.
Code is below. Uses python, finds the VISA connected instruments.
Uses a Rigol DP832 Power supply and a Siglent SDL1020 in my case.
Warning: The code will totally blow up your DUT if you don't configure it correctly.
I suggest manually setting up the Overvoltage and Overcurrent conditions on both your instruments before starting.

[tszaboo]

It was running using jupyter notebook, but there is no reason why it wouldn't work from regular python console.

Code: [Select]

import pyvisa
import numpy as np
import itertools
import time
import csv
import pandas as pd
import matplotlib.pyplot as plt
import datetime
rm = pyvisa.ResourceManager()
[print(x) for x in rm.list_resources()];

#use instrument names OR serial numbers
#Power supply settings
PSU_NAME = "DP832"
VIN_NUMBER_OF_SAMPLES = 20
VIN_MIN = 15
VIN_MAX = 22
IIN_MAX = 1
#DC load settings
DC_LOAD_NAME = "SDL1020"
IOUT_NUMBER_OF_SAMPLES = 20
IOUT_MIN = 0.01
IOUT_MAX = 0.3
DELAY = 0.5

CSV_FILE = 'measurements.csv'
EFFICIENCY_IMAGE = 'Efficiency.png'
VOLTAGE_IMAGE = 'Output.png'
#Creating measurement parameters
VIN = np.linspace (VIN_MIN,VIN_MAX,VIN_NUMBER_OF_SAMPLES)
IOUT = np.linspace (IOUT_MIN,IOUT_MAX,IOUT_NUMBER_OF_SAMPLES)
N= len(list(itertools.product(VIN,IOUT)))
print (f"Taking {N} measurements")
print (f"Expected time: {N*(DELAY+2)} seconds")

#Connecting to instruments
# Example usage:
#instrument_identifier = "DP832"  # Or any other identifier
def find_instrument(instrument_identifier,rm):
  instruments = rm.list_resources()
  for instrument_name in instruments:
    try:
      instrument = rm.open_resource(instrument_name)
      idn = instrument.query("*IDN?")
      if instrument_identifier in idn:
        print("Instrument found:")
        print(idn)
        return instrument
      else:
        instrument.close()
    except:
      pass
  return None
PSU = find_instrument(PSU_NAME,rm)
DCL = find_instrument(DC_LOAD_NAME,rm)

def measure_point(vin, iin, iout):
    PSU.write(f"APPL CH1,{vin},{iin}")
    #if PSU.query(":OUTPut:STATe? CH1").find("ON") == -1:
    #    PSU.write(":OUTPut:STATe CH1,ON")
    DCL.write(f":SOURce:CURRent:LEVel:IMMediate {iout}")
    #if DCL.query(":SOURce:INPut?").find("ON") == -1:
    #   DCL.write(":SOURce:INPut ON")
    time.sleep(DELAY)
    a= PSU.query(":MEASure:CURRent:DC? CH1", 0.1)
    b= PSU.query(":MEASure:VOLTage:DC? CH1", 0.1)
    c= DCL.query(":MEASure:CURRent:DC?", 0.1)
    d= DCL.query(":MEASure:VOLTage:DC?", 0.1) 
    a = float(a.strip())
    b = float(b.strip())
    c = float(c.strip())
    d = float(d.strip())
    #print ((a,b,c,d))
    print(".", end="")
    try:
        eff = (c*d)/(a*b)*100
    except ZeroDivisionError:
        eff = 0
    return vin,iout,eff,a,b,c,d

vin,iout = next(itertools.product(VIN, IOUT))
measure_point(vin,IIN_MAX,iout)
PSU.write(":OUTPut:STATe CH1,ON")
DCL.write(":SOURce:INPut ON")
with open(CSV_FILE,'w', newline='') as csvfile:
    print (datetime.datetime.now())
    headerList = ['VIN','IOUT','EFF', 'CIN', 'VIN_A', 'IOUT_A','VOUT']
    writer = csv.writer(csvfile, delimiter=',')
    writer.writerow(headerList)
    for vin,iout in itertools.product(VIN,IOUT):
        #print (vin,iout)
        m = measure_point(vin,IIN_MAX,iout)
        writer.writerow(m)
#Turn off output
PSU.write("OUTP CH1,OFF")
DCL.write(":SOURce:INPut OFF")
#Beep
PSU.write(":SYSTem:BEEPer:IMMediate")
time.sleep(0.5)
PSU.write(":SYSTem:BEEPer:IMMediate")
time.sleep(0.5)
PSU.write(":SYSTem:BEEPer:IMMediate")
print (datetime.datetime.now())
print ("Measurements done")

df = pd.read_csv(CSV_FILE)
df

plt.tricontourf(df['VIN'], df['IOUT'], df['EFF'], cmap='seismic',levels=30)
plt.xlabel('Input voltage')
plt.ylabel('Output current')
plt.colorbar(label='Efficiency')
plt.savefig(EFFICIENCY_IMAGE)  # Save the plot
plt.show()

plt.tricontourf(df['VIN'], df['IOUT'], df['VOUT'], cmap='viridis',levels=30)
plt.xlabel('Input voltage')
plt.ylabel('Output current')
plt.colorbar(label='Output voltage')
plt.savefig(VOLTAGE_IMAGE)  # Save the plot
plt.show()