Paul & Sabrina's cheap DIY 144v motor controller

[MPaulHolmes]

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.

[z_power]

Originally Posted by MPaulHolmes

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?

[MPaulHolmes]

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.

[adamj12b]

Originally Posted by z_power

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

[jackbauer]

Re-moc progress. Getting to like those C4DE caps .........

[adamj12b]

Originally Posted by jackbauer

re-moc progress. Getting to like those c4de caps .........

that is awesome!

[jackbauer]

Re-moc is alive! Video uploading .........

[MPaulHolmes]

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.

[SEBART PL]

Originally Posted by jackbauer

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.

[cyrusamory]

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