4Q Motor control paradox

Sure, if you used the same 0 all the way through.

DNA

Like perlease go and read my posts on the origin of the universe.

Ignorofuck...

DNA

Bwahahahaha!

...Jim Thompson

I don't think so, because if Speff was picking on this sentence, he would have pointed out that a preposition is the wrong thing to end a sentence up with.

If you have a low resistance motor, which limits its current by generating back EMF, then when you short it (perhaps by switching on both your fat low-side MOSFETs), you get very rapid braking and your MOSFETs, wiring or motor go pop.

If you want to regenerate into the power supply, you short the motor until the current builds (based on L/R) to a predetermined level, then you quickly switch, steering that current into the supply until it drops again. Rinse and repeat for amount of the braking you want.

In a similar vein, if you are driving along at full speed, and slam the car into reverse, something will go bang.

Cheers Terry

If you apply a whole lot of current backwards the motor will stop and reverse pronto. Or it may not. I saw something like it, due to a mix-up between signed and unsigned words in a drive controller. Shiny new rewinder being tested, two 3 kW motors drive it. Hit the ramp-up button and see it go faster. Nobody stops to wonder why at supposedly half-speed it's already going hell-for-leather, just ramp it up a bit more. That's when the sign bit flips. Blue and yellow flames shoot out of the motors and everybody clears the area while it winds down on its own.

In the end the damage wasn't too overwhelming, new brushes, a new coupling and new fuses for the drive set it right again.

- YD.

Any new pairs of pants?

For some reason I try to be _really_ careful to avoid integer overflow. It can be exciting, but not in a career-advancing sort of way.

At least not for me.

It was a contract job so this time around it wasn't me doing the programming. I do try to hook up simulators and meters to the I/Os and sweep them around before connecting to the field.

- YD.

For very large values of 0?

- YD.

overflow.

Ah dont know:

A former colleague insisted that a director in Siemens, which he knew from university, became a manager because he on his first assignment blew up a 1 MW generator he was supposed to commision and was moved to the management career track to contain the risk.

Some years later the promotion board goes through the list, they recognise a name (but do not remember *why* ... ) and the guy gets the interview & the job ;-)