FSAE Electric: Precharge | Intro & voltage-feedback design

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  • @MichaelRuppe
    @MichaelRuppe  4 ปีที่แล้ว +7

    Warning! I drew the discharge circuit incorrectly. Of course, the negative side should remain on the TS side of the AIR-

    • @gizmodobaggins7040
      @gizmodobaggins7040 4 ปีที่แล้ว

      Why can't the discharge circcuit go to the accumulator side of the AIR-? Also, how does the discharge circuit discharge if not connected to the accumulator? If it just discharges into ground, i'm just used to ground being connected to the negative side of a battery.

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว

      @@gizmodobaggins7040 the discharge circuit is for the capacitance in the Tractive System - not the accumulator. Isolating it from the TS would defeat the purpose which is to make the TS safe quickly after the AIRs open. If it's connected to the accumulator-side of the AIR- it can't do this.

    • @gizmodobaggins7040
      @gizmodobaggins7040 4 ปีที่แล้ว

      @@MichaelRuppe What size resistance did you use for the voltage dividers for measurement? I would imagine you don't want a lot of power used by it so they would be quite large?

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว

      @@gizmodobaggins7040 they are pretty large. Check the schematic in the repo

  • @mathbrook
    @mathbrook 2 ปีที่แล้ว +3

    Hey Michael! just wanted to leave another comment since i've now successfully implemented my own modified version of your design. i removed the resistor overtemp circuitry, moved the resistor off-board, and swapped various parts like the optos, HV relay, and so on. cheers!

    • @MichaelRuppe
      @MichaelRuppe  2 ปีที่แล้ว +2

      Hey great! I'm glad open-sourcing the design was helpful for someone

  • @jakesprenger1378
    @jakesprenger1378 3 ปีที่แล้ว +1

    Hi Michael, would this approach work as well? Instead of using a V-F converter, why not have a microcontroller on the HV side which measures the voltage at the divider. Then it can communicate over Serial through the optocouplers to the mcu on the low voltage side. Thoughts? And thank you for the advice!

    • @MichaelRuppe
      @MichaelRuppe  3 ปีที่แล้ว +2

      Totally, you could use a micro. It would simplify nicely. I briefly mention that in the 'recommendations & to do' section.

  • @milan2931
    @milan2931 2 ปีที่แล้ว

    Thank you for the video, I need this for my HV storage.
    Just a question - wouldn't it be enough to simply connect the optocouplers to both sides of the charging resistor via the divider and compare the voltage differential? Either it's within the allowed range and it turns on the relay, or it's not within the allowed range and nothing turns on. Absolute voltage values are irrelevant I think.
    Sorry, I'm not an expert :)
    One more question, can this board be bought?

  • @choncosaurus7331
    @choncosaurus7331 11 หลายเดือนก่อน

    Hey Michael i want to implement your design, but im having a difficult time understanding function of all the components. could you assist me with right documentation and information?

  • @shubhamkarekar7695
    @shubhamkarekar7695 4 ปีที่แล้ว +2

    Really good explanation of the precharge circuit! It really cleared my concepts and now have a very clear understanding of precharge.
    I had some doubts regarding precharge in general
    1) is resistor divider a good measure of the voltages? Because a small error in the resistor value will cause a very big change in the corresponding high voltage measurement... especially if its around 500V
    2) can we use an isolated adc directly instead of converting to voltage and then frequency?
    3) are there any other possible approaches for precharge?

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว +1

      1) you're right about small errors being magnified. Resistors should be 1% and you can be conservative with parameters in the program to guarantee adequate precharge.

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว +1

      As for your other two questions, there are *certainly* other ways to do this. AND there are certainly better ways. This is the way I chose given the resources and knowledge I had at the time.
      An isolated ADC sounds great! You would remove the v-f complexity and the calibration requirements

    • @shubhamkarekar7695
      @shubhamkarekar7695 4 ปีที่แล้ว

      @@MichaelRuppe thanks alot!
      One more small doubt...i read the datasheet of the voltage to frequency converter...it says that it can handle input voltages upto 40V max....so will scaling high voltage to 0-40V have a significant improvement in accuracy?

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว +1

      @@shubhamkarekar7695 higher input voltages will help with error tolerance, but be careful. That 40V sounds like it could be the *absolute* maximum, which should be well avoided.
      Remember that you can also characterise the response and calibrate out any errors

  • @noahlape8187
    @noahlape8187 2 ปีที่แล้ว +1

    Really awesome video! Thank you

  • @liziye1982
    @liziye1982 ปีที่แล้ว +1

    thanks for the info! really helpful mate!

  • @mmrakshith1715
    @mmrakshith1715 4 ปีที่แล้ว +1

    Thanks a lot Michael!! I understood this very well

  • @blackterminal
    @blackterminal 2 ปีที่แล้ว

    You are very clever. thank you for you for making this video. Parts were over my head but it was still interesting. :)

  • @shubhamkarekar7695
    @shubhamkarekar7695 4 ปีที่แล้ว

    Im refering to the schematic that you have uploaded on github....i saw that that there are two high voltage grounds, Gnds and TS- ....Both these grounds have been connected using a 0 ohm resistor...is there and specific reason to do this? Also do they refer to the same ground?

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว

      They are the same ground, I did this to create a specific path for the analogue ground. If you refer to the pcb project you will see how it is routed independent of the ground plane. This isn't strictly necessary because there are no large currents flowing in the ground plane anyway - I was just playing with the idea

  • @mathbrook
    @mathbrook 2 ปีที่แล้ว +1

    sweet vid dude, and iirc the rules(at least for american comp) now require actual monitoring of the precharge voltage rather than just charging for a conservative amount of time

    • @satiric_
      @satiric_ ปีที่แล้ว

      I know this is an old comment, but the FSAE rules do actually still allow time-delay precharge. They probably shouldn't though haha

  • @craiguk62
    @craiguk62 4 ปีที่แล้ว

    Yes, if you infer the Inverter voltage from signals inside the accumulator housing then there are open-circuit failure modes that can trip you up. Therefore detecting a pre-charge that is too fast takes care of those. Good idea. The messier solution is to wire the actual inverter voltage back into the accumulator housing, to the pre-charge controller, and perform a direct comparison between accumulator and inverter voltages. Thanks for sharing.

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว

      Thanks for taking the time to have a watch, Craig

  • @thiruvarulselvank1695
    @thiruvarulselvank1695 3 ปีที่แล้ว

    What if I use two accumulators with two pairs of main contactors, do I need two precharge circuits. If so how to sync them.

  • @sajjukarapparambilthomas2049
    @sajjukarapparambilthomas2049 2 ปีที่แล้ว

    How do you power That voltage frequency converter, Do connect it to GLV Battery? if that's the case, does it break the galvanic isolation rules??

    • @MichaelRuppe
      @MichaelRuppe  2 ปีที่แล้ว

      See my other reply about the SPAN02 DC-DC converter

  • @mobiemoto
    @mobiemoto 4 ปีที่แล้ว

    Hey Michael, Fantastic explanation for me to look at and understand very easily with year 11 knowledge. I just have a few questions?
    1 - What does it take to get into FSAE?
    2 - What kind of hours and training is put into building and creating the Formula Students Cars?
    3 - What kind of knowledge do I need to understand the basics of FSAE
    I have been practising on Assetto Corsa (Im pretty serious about join, as its what I have been working towards to drive and make a Formula Car)
    Thanks

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว +2

      Hey, thanks for watching - apologies I must have missed the notification. Fsae represented about 1000 hours over 12 months for me and many others on my team. The time commitment is nontrivial, and financially its no joke either - in general fsae teams are funded by their universities and obtain sponsorships for funding/parts.
      It was seriously the best way for me to finish my studies though

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว +2

      As for knowledge - it's a practical project so a lot of knowledge is built *during* the project. For my role, a background in hobby embedded electronics and circuit design certainly didn't hurt. For others, being racing enthusiasts and having experience with mechanical hardware was critical. It seems that your prior experience will help you fall into a role neatly. if you have limited experience, leading a project on the car will fast make you a subject matter expert in that area

  • @jakesprenger1378
    @jakesprenger1378 4 ปีที่แล้ว +1

    Hey Michael, thanks for the video - fantastic explanation of the system. Quick question that I'm hoping you could answer. What's the advantage of measuring the voltage across the precharge resistor? Would it not make more sense to measure the voltage across the capacitor, since you can then detect a few more failure methods? I was thinking that the TSAL and precharge circuits could make use of the same voltage divider to perform their respective duties.

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว

      Hey Jake. This circuit does measure the voltage across the capacitor: the Tractive System voltage. That is the measurement downstream of the resistor. It's not the voltage *across* the resistor being measured, but rather the upstream and downstream voltage are being compared. The point here is to have a voltage-sensitive precharge strategy that works regardless of accumulator voltage or state-of-charge

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว

      You could absolutely combine the TSAL circuitry into this. On our car the precharge unit is in the accumulator, and the TSAL controller elsewhere

    • @jakesprenger1378
      @jakesprenger1378 4 ปีที่แล้ว

      @@MichaelRuppe That makes sense - thanks for the clarification! Thanks a ton!

    • @jakesprenger1378
      @jakesprenger1378 4 ปีที่แล้ว

      @@MichaelRuppe Hi Michael, follow up question - hope you don't mind. Do you ground all the tractive system components to the HV- line? Just wanting to know if there's any reason why that wouldn't be the case. Seems intuitive, but thought I'd ask to be sure.

  • @sparshsinghg
    @sparshsinghg 4 ปีที่แล้ว

    Is programmable logic allowed for precharge circuit as per FSAE rules ?

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว +1

      As far as I know there is only a stipulation that elements of the shutdown circuit must be non-programmable. The shutdown circuit handles the safety of the EV, and the precharge is powered directly by the shutdown circuit. I believe that means a programmable precharge is acceptable.

  • @mehullad7511
    @mehullad7511 4 ปีที่แล้ว +2

    What about the provisions of Galvanic isolation between the the potential divider u used and voltage to frequency converter ,I believe According to fsae rules we do need to provide galvanic isolation between high voltage system and low voltage component ,even though if we drop down the voltage of the accumulator still it is from high voltage side .
    If the v tof conevertor is galvanically isolated ,can u share the ic number

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว +2

      Good question! The VF converter is powered by a SPAN02A-12 isolated DC-DC converter. Together, the SPAN and the optocouplers galvanically isolate the VF converters from the GLV.
      Take a look at the schematic for the finer details

    • @mehullad7511
      @mehullad7511 4 ปีที่แล้ว

      Okay ,so the ground which will be used for powering this v to f convertor ,will be a high voltage ground / acc-
      Correct me if I am wrong ?
      Also I tried access the schematic from your drop down GitHub link ,I couldn't I guess it has been removed can u plz re-upload it .
      Or even u can mail it ,it will work ( ps - if u don't mind )
      Mail id - mehul.lad8390@gmail.com
      Thank u very much !

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว +2

      @@mehullad7511 try this one github.com/michaelruppe/FSAE/tree/master/Precharge

    • @mehullad7511
      @mehullad7511 4 ปีที่แล้ว

      Thanks a lot @michael

  • @theormsta
    @theormsta 4 ปีที่แล้ว

    Hi Michael I need some help to build a pre-charger and a dis-charger how do I get in contact with you

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว

      Perhaps open an issue in the repository

    • @theormsta
      @theormsta 4 ปีที่แล้ว

      @@MichaelRuppe Send a issue on Git. Thanks for the answer

  • @hayagriva9571
    @hayagriva9571 10 หลายเดือนก่อน

    hey michael, i am trying to access the github files, but none of them seem to open, nor could i download the raw files. Could you help.
    Great video, helped alot.

    • @MichaelRuppe
      @MichaelRuppe  10 หลายเดือนก่อน

      They are kicad files - are you using kicad?
      Glad you enjoyed the video!

    • @hayagriva9571
      @hayagriva9571 10 หลายเดือนก่อน

      @@MichaelRuppe but i can still download them right, i am not able to download the pdf's or even view the images

    • @MichaelRuppe
      @MichaelRuppe  10 หลายเดือนก่อน

      @@hayagriva9571 you can download the whole repo as a zip file and extract it. Have you done that?

  • @sivashankarim2134
    @sivashankarim2134 ปีที่แล้ว

    can share the schematic digram of the precharge circuit which u have designed

    • @MichaelRuppe
      @MichaelRuppe  ปีที่แล้ว

      Its linked in the description

  • @oliverwijesooriya2067
    @oliverwijesooriya2067 3 ปีที่แล้ว

    Excellent explanation 👌

  • @timmothyburke
    @timmothyburke 4 ปีที่แล้ว

    Can I get some help designing a precharge circuit for
    My off grid system?

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว

      Hi Tim. Do you have some place where you can share your work so far? A link to a stack exchange post would be great - and you can get input from the rest of the community too

  • @GauravSuman-p1z
    @GauravSuman-p1z ปีที่แล้ว

    can we charge Capacitor using constant current ?

    • @MichaelRuppe
      @MichaelRuppe  ปีที่แล้ว

      Sure, you'll just have to figure that part out separately.

  • @tolga3115
    @tolga3115 4 ปีที่แล้ว

    Hey! Can u also add schematic files for precharge and AIL in pdf format? I couldn't see them through your GitHub account :c

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว

      The precharge schematic is in the repo: docs/schematic-v1.1.pdf

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว +1

      The AIL was part of the early TSAL design. This schematic includes the AIL functionality
      github.com/michaelruppe/FSAE/blob/master/TSAL/TSAL-HVM/schematic-tsal-hvm-v2.1.pdf

    • @tolga3115
      @tolga3115 4 ปีที่แล้ว +1

      Oh, thank you so much!

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว +2

      @@tolga3115 You're welcome. As far as accumulator indicator goes you might be better off with an analogue voltmeter. Also, be careful with that design - check the maximum voltage rating of the regulator. It isn't that high

  • @bubster2a
    @bubster2a 4 ปีที่แล้ว +1

    Very nice video! Could you do another about cell stackup methods?

  • @craiguk62
    @craiguk62 4 ปีที่แล้ว

    Which team are you with Michael?

    • @MichaelRuppe
      @MichaelRuppe  4 ปีที่แล้ว +3

      NU Racing - the University of Newcastle. We made our debut in FSAE Electric last year

  • @sivashankarim2134
    @sivashankarim2134 ปีที่แล้ว

    can share the schematic digram of the precharge circuit which u have designed

    • @dylankaira8019
      @dylankaira8019 3 หลายเดือนก่อน

      do you have the schematic diagram ?