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Old 05-05-2017, 11:24 PM   #7161 (permalink)
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Quote:
Originally Posted by duncan2 View Post
I'm direct drive to the diff so I am going to use the old ABS sensors on each wheel as my data for the traction control and also the speed/rpm limiter
Sounds like a good plan.

Quote:
I was thinking about adding the two rear wheel speeds together and comparing to the sum of the two front wheels

I was thinking of a separate module interfacing with the throttle input on the main controller

So it would drop down the throttle input when the tires start to spin - as opposed to just now when the first thing I know is that the tires scream and the back overtakes the front
I would think that Left + right / 2 / rear-end gear ratio should give you motor rpm.

A separate module sounds like a good plan. ABS modules are a part of all of the cars that I know about ... precious little that I do actually KNOW ..

Others have posted silly little messages to get to the fifth post, where you can begin to include links

Is this the link you wanted to post?

Duncan's Dubious Device - DIY Electric Car Forums

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Old 05-05-2017, 11:34 PM   #7162 (permalink)
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Yep that's my thread!
The Device is great fun

I suppose this is number post three - only two to go!

I'm happy about mechanical stuff - I need to learn the electronic stuff
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Old 05-05-2017, 11:38 PM   #7163 (permalink)
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Post Four

I need to decide what speed I actually need

The road speed limit here is 100Kph
The grass events I have been doing are relatively low speed and even the tarmac ones have a limitation on the allowable length of the straights

The only place where I hit my max speeds is at the drags - I hit 140kph at the 1/8th mile
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Old 05-05-2017, 11:39 PM   #7164 (permalink)
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Do I want to increase my maximum speed so that I can dare try a 1/4 mile drag race?

Or am I best with a speed limiter?
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Old 05-05-2017, 11:41 PM   #7165 (permalink)
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Originally Posted by duncan2 View Post
I suppose this is number post three - only two to go!

I'm happy about mechanical stuff - I need to learn the electronic stuff
I'm the opposite, I'm afraid. If it has wires, I can get it to work.

But aligning mechanical stuff ... or getting a bearing pressed on .. purging the air from a clutch ... like magic!
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Old 07-11-2017, 07:04 PM   #7166 (permalink)
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Is the hardware overcurrent, set by VR1, an actual TRIP/Shutdown, or does it simply cut back the PWM signal?
I'm having an issue with a modified, overpowered, PS board. When I hit full amps, 511 as seen on the RTD explorer, it seems to cut way back on power, even through the PWM still says full voltage?
I was running about 1250 amps (seen as 511) at only 50% PWM, for about one second, then power fell off, PWM showed 100%, but it felt like about 25% power.
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Old 07-13-2017, 12:37 AM   #7167 (permalink)
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Quote:
Originally Posted by badfishracing View Post
Is the hardware overcurrent, set by VR1, an actual TRIP/Shutdown, or does it simply cut back the PWM signal?
As far as I know, it is a hardware detection circuit that disables the MOSFET driver, and it latches the over-current, and it displays a fault code, and you need to cycle power to get the Cougar to turn on the MOSFETs again.

Since it is hardware it is *FAST* ... the output from the current sensor is compared to a reference voltage with a comparator. When the voltage from the current sensor is above the reference voltage, the output of the comparator changes and the MOSFET driver is disabled.

I believe that there is a latch in there, but the micro may do the latching.
I'm a bit fuzzy on the details.

Paul will have to answer whether, under some weird set of circumstances, the High Current Fault would NOT latch, and if it didn't latch, how fast the circuit would enable after the current falls off (since the MOSFETs are turned off) before the MOSFETs are turned on again.

But this would not be normal operation!

Quote:
I'm having an issue with a modified, overpowered, PS board. When I hit full amps, 511 as seen on the RTD explorer, it seems to cut way back on power, even through the PWM still says full voltage?
Modified and over-powered? How are you getting rid of the heat? You need a *LOT* of air moving across the heat sinks to get rid of that much heat.

Heat is proportional to the square of the current. I think that's one of the reasons that electric cars use such high voltages - the power electronics are easier to cool. And the copper wires don't need to be as big. And the contactors don't have to be as big

Is it possible that the modifications messed up the latch on the overcurrent somehow?

Quote:
I was running about 1250 amps (seen as 511) at only 50% PWM, for about one second, then power fell off, PWM showed 100%, but it felt like about 25% power.
The PWM does not need to be very high at low revolutions to draw high amps. If the back EMF from the motor is low, lots of current can flow. But I guess that's why you built that DC Monster Controller!

What you describe sounds more like a heat issue to me. As the MOSFETs pump the amps, the temperature sensor gets hot, the PWM is limited to reduce the heat .. that sort of thing. I don't know where in the code (before or after the display section) the PWM is backed off.

*BUT*... there are others on this board who have hands-on experience with the Cougar and will give you a better idea on what to chase.

These are only my opinions, after all. I don't have an operational original Cougar 500A (although I did KILL one)
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Old 07-16-2017, 07:07 PM   #7168 (permalink)
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Hi Paul
Are you selling the high voltage DC controller? - and where can it be bought from?
With the Soliton going away there are people looking for replacements

Mine is still going great but If there is any more advanced software - especially around the ramp up time I would be interested in updating mine before the spring

Thanks
Duncan

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