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Old 05-30-2013, 10:12 AM   #6141 (permalink)
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Power into the motor is approximately power out of the motor (except for losses), so...

1) BatteryCurrent * BatteryVoltage = MotorCurrent * MotorVoltage.

Now,
2) MotorVoltage = BatteryVoltage * PWM_DUTY

Let's substitute 2 into 1:

BatteryCurrent * BatteryVoltage = MotorCurrent * (BatteryVoltage * PWM_DUTY)

Now, cancel BatteryVoltage from both sides of the equation, to get....

BatteryCurrent = MotorCurrent * PWM_DUTY.

Or, said another way,
BatteryCurrent / MotorCurrent = PWM_DUTY

So, if you only know the PWM_DUTY, there are still 2 other variables. You can't know both the battery current and the motor current if you only know the pwm duty.

Hey! It has over 1 million views! I was hoping it would roll over to zero, and there'd be a y2k catastrophe. oh well.

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Old 05-30-2013, 10:36 AM   #6142 (permalink)
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Yes, it's just a single line of code to go up to maybe 900 amps. Well, or maybe 2 lines. I forgot...
Thanks! I tried to dig into code (being a beginner means it's like deep water diving) and I understand that these mentioned lines simply change translation of LEM signal onto current_fb; so for example current_fb=500 means ~600A real; to get rtd_explorer displaying proper values we'd need to modify either rtd_explorer or cougar's output datastream?
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Old 05-30-2013, 11:11 AM   #6143 (permalink)
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Oops. Yes! That's exactly right. 0 to MAX_CURRENT would be 0 to 500 (or 511 haha)

The code on the chip would have to do a multiply by 600/500 before displaying it.
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Old 05-30-2013, 11:48 AM   #6144 (permalink)
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Originally Posted by z_power View Post
Thanks! I tried to dig into code (being a beginner means it's like deep water diving) and I understand that these mentioned lines simply change translation of LEM signal onto current_fb; so for example current_fb=500 means ~600A real; to get rtd_explorer displaying proper values we'd need to modify either rtd_explorer or cougar's output datastream?
RTD Explorer filters incoming data with a REGEX. I would have to check it and make sure it can take a larger value, but I think it is just looking for format. Which means any current up to 999 would be ok.

-Adam
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Old 05-31-2013, 11:54 AM   #6145 (permalink)
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Re-moc progress. Getting to like those C4DE caps .........
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Now, Cole, when you shift the gear and that little needle on the ammeter goes into the red and reads 2000 Amps, that's bad.
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Old 05-31-2013, 12:15 PM   #6146 (permalink)
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re-moc progress. Getting to like those c4de caps .........
that is awesome!
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Old 06-02-2013, 11:35 AM   #6147 (permalink)
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Re-moc is alive! Video uploading .........
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Now, Cole, when you shift the gear and that little needle on the ammeter goes into the red and reads 2000 Amps, that's bad.
www.evbmw.com
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Old 06-02-2013, 12:32 PM   #6148 (permalink)
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Oh heck ya! Hurry up and upload, you stupid computer!!!!! I just about have to leave. dang it. I'll get that code changed too so that it shows the actual amps instead of the scale of 0-500.
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Old 06-02-2013, 02:22 PM   #6149 (permalink)
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Re-moc is alive! Video uploading .........
...where is this video , please? ( I have checked your youtub profile but is not there)

After my second set of mosfet failed, I have decided to put more of them in TO220 case
- I want to change IRFP4668PbF for irfb4115gpbf (150V 11mohm 70A ) 22 pieces

1. I want to ask is mic4451YN can manage those 22 mosfets? And do I need to change resistors gate parametrs ?

Data S:
mic4451YN http://www.micrel.com/_PDF/mic4451.pdf

MOSFET Ciss Input Capacitance ––– 5270 ––– pF x22=115940 pF
mic load drive is 62000 Pf looks it is not good
or I need to check just Gate-to-Source Forward Leakage it is 100nA and mic can work on 2A - I am not so sure is this is OK.

2. What about resistors, have they need to be amended?

3. Another important question I aware my fail could happened becouse of spikes from motor could produce over voltage - can I protect my controler with some kind diode or transil installed on motor? (Motor parametrs 80V 200A 13.5 KW DCseries)

For any help thank you in advance.

Last edited by SEBART PL; 06-02-2013 at 05:04 PM..
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Old 06-03-2013, 04:24 AM   #6150 (permalink)
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Me Again

Looking at the spec sheet for the IXYs mosfet, It appears to have a Diode integrated into the device between the drain and source, could this replace the freewheel diode? here is the spec sheet.

http://ixdev.ixys.com/DataSheet/DS10...FX230N20T).pdf

Thankyou again


Last edited by cyrusamory; 06-03-2013 at 04:25 AM.. Reason: Missing Link
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