Minimize controller brake down - Fuses inline with phase?

Morning all .

After my Adaptto stopped functioning for the second time, I believe it's time to try to tackle an issue that could prevent controllers braking the world over .

To avoid immediate confusion this is not about battery->controller it's controller<->motor .

First, why aren't we all putting phase current rated fuses inline with each phase in the motor? Either rate the current to your max phase/regen current, whichever is higher. I've spotted a few fuses online some inexpensive others more pricey.

Is anyone using this idea already or implemented something similar? I'd like to hear real world experience ... whilst I'm waiting for parts to be delivered.

Just think a wet motor, phase wires cut, perished insulation, motor overcurrent can all likely damage your controller and by simply having a fuse/protection device on our phases we could save so much extra time, hasstle and hard earned cash! We do it in industry so why the dickens not the EV environment?

Second, more for the Adaptto user base, 2x4 stackable female. These Adaptto units are generally great, however they've packed everything in close together, so getting to some of the FETs means removing the 'phase drivers'. If your out of warrenty and opened the unit up these 2x4 unit's for a few quid will save you time in the future when you inevitably have to go back inside.

At a guess, the fuses will blow slower than the FETs, but it's worth a shot if you use fast-blow fuses.

Some old audio amps used fuses on each speaker output, cuz when they came out FET amps were incredibly expensive (and sometimes finicky, especially compared to tubes). the fuses did not always save the FETs.

WHile there might be solutions to fusing a high-power (over 5A) fet driver, I'm not really aware of any that offer 100% protection.
The issues of fusing to protect solid-state devices is discussed in this tech tip by Crydon; a solid-state relay manufacturer so it's mainly about protecting thyristers.
-But the general info is applicable to all solid-state devices.
http://www.crydom.com/en/tech/tips/how%20to%20select%20the%20right%20fuse.pdf

Since I retired from engineering almost a decade ago I'll say this: things change
...where my interest in new circuitry is at an all-time low. Basically non-existent.

Cheers guys,

Had a bit more of a read through some pdfs on FET protection and with ref you've given ddk although not completely the same product as you say, the form of manufacture is similar. Due to the fast response times of solid state components in general, any fusing or protection has to be faster again, just as you say amberwolf .

It would seem a simple 'plug and play' type solution isn't entirely feasible for quick and easy roadside repairs.

amberwolf said:

At a guess, the fuses will blow slower than the FETs, but it's worth a shot if you use fast-blow fuses.

Some old audio amps used fuses on each speaker output, cuz when they came out FET amps were incredibly expensive (and sometimes finicky, especially compared to tubes). the fuses did not always save the FETs.

Click to expand...

Remember I had a NAD amp that would go cold if pushed to hard. I never opened up that amp, as it would work after a few minutes of cooling.
I wonder how NAD did this? I mean it couldn't be blown fuses, for that would mean I would have to replace those fuses. Later on I have thought of that behavior of the NAD amp, but never figured out how they did it.

Could it be some weird bi-metal fuse thingy? Like on automobiles, where Bi metal is used to open/close coolant circulation?

So that if heated too much, connection/switch off. Cool down and switch on?

Self-resetting thermal circuit breakers aren't unknown.

But it would be more likely to have simply been a standard setup with thermal shutdown, simply monitoring a thermistor on the heat-sensitive parts, and then turning off the amp (or it's power supply) to protect it.

I've had plastic fuses catch fire when thrown by lipo.
Plasma arc inside burns so hot the plastic case starts to smoulder.

I made the point in another thread. Luke LFP rightly pointed out this is a known phenomena and that for high amps via Lipo a proper circuit breaker with a ceramic arc quench tunnel is needed to avoid.

Stuff is maybe gonna get interesting in audio stereo land when they start using high amp lithium batts.