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  • Author Author: Jan Cumps
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How I Enroll for a RoadTest - Part 4: Case for Programmable Electronic Load

Jan Cumps

The element14 roadtests are a great way to learn new things. Whenever I see a test that interests me, I enroll.

Success is not guaranteed. I've been selected for some, not for others. In this series I'll explain how I decide to enroll or not.

I'll also show how I build my case, including some examples from my applications.

 

This is the technical part of my application for the Programmable DC Electronic Loads with the BK8600 image

All technical content is here. I've removed the part where I'm doing blatant self promotion, because that's none of *your* business image .

I wasn't selected. image

 

My plan with the electronic load is to show how the instrument is used in a real lab situation.

I have technology preview GaN FETs in the lab, medium-voltage (80 V) and high-voltage (600 V) ones.

 

I want to deploy the  BK8600BK8600 as the configurable load to help validate the efficiency of the early production GaN FETs versus the specifications.

 

image

 

 

I have created  a precision test bed for the GaN devices,

I can have them in a buck configuration, driven by a industrial safety microcontroller.

I can program the switch frequency, duty cycle, and a dead-band as low as 10 ns.

This programmable driver together with the programmable  BK8600BK8600 can be used to drive the test configuration.
I can change both the input signal and the electronic load in an automated setup and record the efficiency of the devices.

 

 

I will put the instrument to real use, and will make sure that I fully understand it before giving the RoadTest verdict.

My blogs will cover:

  • The use cases for a programmable load in a lab, the precision of the  BK8600BK8600 in the low ranges and the capabilities in the upper ranges
  • How to program the instrument and a write-up of my first attempt to program a real world test in the blog
  • A series on how to check the GaN FETs performance versus Texas Instruments specification:
    how to use the load to validate cutting edge technology
  • An honest and tough review report of the  BK8600BK8600 after a full evaluation
    its possibilities, user interface, documentation, its programming capabilities and the things I like or don't like.

 

< the blatant tapping @self on the shoulder removed >

 

 

 

 

Related blog
How I Enroll for a RoadTest - Part 1: yes or no
How I Enroll for a RoadTest - Part 2: success and failure
How I Enroll for a RoadTest - Part 3: Help Me
How I Enroll for a RoadTest - Part 4: Case for Programmable Electronic Load
How I Enroll for a RoadTest - Part 5: Case for Educational Switch Mode Converter Lab

How I Enroll for a RoadTest - Part 6: Case for CAN Analysis Tool

How I Enroll for a RoadTest - Part 7: Case for Some Other Road Tests
How I Enroll for a RoadTest - Part 8: Case for Harting Mica Road Tests
How I Enroll for a RoadTest - Part 9: Case for Renesas RX65N, Trinamic TMC2300, Infineon Block Chain, STM32H7B3I DISCOVERY KIT
  • in reply to Jan Cumps

    Not being selected was the trigger for this project: Programmable Electronic Load.

    Loads of things learned along the way.

  • in reply to Jan Cumps

    Got a big box of 50W and even 75W GU10 bulbs. Interested ? image

  • in reply to jc2048

    I'm going to review the GaN devices, also without the electronic load.

     

    I'm aware of the cold/hot characteristics of the indescendant wire. When lit, it is close (enough) to its specs. The very low resistance when cold may also be useful in low voltage settings where I want to drain some current without going fancy.

     

    Coincidently, I had a brief tweet discussion with on using old lamps as a load decade. He removed 10s of lamps from his house (halogen spots I believe, so even stranger nonlinear load characteristics image )

  • in reply to Jan Cumps

    Sorry you didn't get selected. I was hoping I'd see those GaNs doing their stuff.

     

    Your measured cold resistance is 1.6ohms. That's 7.5A on a 12V supply (just showing off that I can use Ohm's law, there). When it's warm the current will, presumably, drop to 15W/12V = 1.25A, so it's a bit of a variable load, though it could be a nice aggressive test for a PSU - slug it at the start and see whether it can bring the power up cleanly.

     

    I can't see any reason why you shouldn't switch it with a MOSFET for doing transient tests. Tungsten lamps are largely resistive, apparently, so it should be fine until you get to the kind of currents/frequencies where the lead inductance becomes an issue. A way to elaborate it would be to add a current sense (resistor with an amplifier). A processor could then allow the bulb to heat up until it reached the desired test current (obviously limited to what was obtainable between the cold and hot resistances), momentarily take it out of circuit, reapply it and then you'd be doing a transient test at that current.

     

    Another thought I had, inspired by your picture, was of a digital load where you switch lots of smaller bulbs. Would look really cool and retro if you had a mahogany case, brass lamp holders, and large toggle switches with little escutcheon plates reading 'ON' and 'OFF'. A processor and a handful of MOSFETs would then make it IoT ready. [Bet the engineers at B&K are wondering why THEY don't have great ideas like this.]

     

    Anyway, enough of my musings; have fun with all the investigations.

  • Because I'm not selected for the road test, I'm improving my analog load image.

    I'ts a 12 V 15 W lamp. Precision, stability and programmability are not its strongest point. But it can dissipate good power at low voltages.

     

    image

     

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