Any dummies guides for this ? Parts to use ?
ie whether to PWM fuel pumps, fans, water pumps etc.
Are solid state relays ok ?
If so, any brands or types favoured ? Any wiring considerations ?
H Bridge ( I know little of ). I see various high current ones on egay, but most seem aimed at Arduino use ? Does it matter ?
PWM motor control ?
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pat
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Re: PWM motor control ?
Stevie,
I don't think there are any dummies guides as such, and there are many options so it is probably best if you could describe what you want to control.
You can of course PWM fuel pumps, fans etc. The ECU will generate the PWM signal on whichever pin you ask it to. That choice will depend what you indend to drive and how you intend to drive it. If you want to drive it directly from the ECU then a spare FUEL or PWM/AUX output would be used. If you want to control more current than the ECU outputs are rated to then you could look at external drivers in which case you may prefer to use an IGN output for the control signal.
SSRs can be OK if they're up to the task and if they can handle the switching frequency. Switching losses happen whilst switching so the faster you switch, the greater the losses for a given amount of current being switched.
You'll need a DC controlled DC SSR, and one that can be switched quickly.... some will be specced for on/off type operation, eg normal fan type stuff where it turns on and then stays on for a few seconds. I have no specific recommendations, just look around and see if the datasheet looks favourable. Wiring wise it is important to remember things like parasitic / stray inductance which can cause ground bounce and thereby cause unexpected triggering of the device. It is probably best to load up the input a little if you can't avoid runs - then at least the interference has to have enough grunt to drive some current through the input impedance of the SSR.... place the pull-down resistor close to the SSR if using only one, or one at the ECU and one at the SSR if you're worried about EMI travelling back into the ECU output stage.
Half and full bridges are good if you need to control the speed and direction of a brushed DC motor. Our unit just takes a 3.8kHz command signal and converts that into forward or reverse drive, chopping at 32kHz if memory serves. 50% is no drive, lower is back, more is forward. Note that the PWM outputs on the ECU are not guaranteed phase coherent so you cannot use a pair to drive a pair of half-bridges and expect that it will behave properly as a full bridge. You can either use a full bridge with a single input, which will then give complementary drive, or you can use the approach we do where we sample the signal and then turn it into a pair of phase coherent signals which are not operating in full antiphase.
Hope this helps a little,
Pat.
I don't think there are any dummies guides as such, and there are many options so it is probably best if you could describe what you want to control.
You can of course PWM fuel pumps, fans etc. The ECU will generate the PWM signal on whichever pin you ask it to. That choice will depend what you indend to drive and how you intend to drive it. If you want to drive it directly from the ECU then a spare FUEL or PWM/AUX output would be used. If you want to control more current than the ECU outputs are rated to then you could look at external drivers in which case you may prefer to use an IGN output for the control signal.
SSRs can be OK if they're up to the task and if they can handle the switching frequency. Switching losses happen whilst switching so the faster you switch, the greater the losses for a given amount of current being switched.
You'll need a DC controlled DC SSR, and one that can be switched quickly.... some will be specced for on/off type operation, eg normal fan type stuff where it turns on and then stays on for a few seconds. I have no specific recommendations, just look around and see if the datasheet looks favourable. Wiring wise it is important to remember things like parasitic / stray inductance which can cause ground bounce and thereby cause unexpected triggering of the device. It is probably best to load up the input a little if you can't avoid runs - then at least the interference has to have enough grunt to drive some current through the input impedance of the SSR.... place the pull-down resistor close to the SSR if using only one, or one at the ECU and one at the SSR if you're worried about EMI travelling back into the ECU output stage.
Half and full bridges are good if you need to control the speed and direction of a brushed DC motor. Our unit just takes a 3.8kHz command signal and converts that into forward or reverse drive, chopping at 32kHz if memory serves. 50% is no drive, lower is back, more is forward. Note that the PWM outputs on the ECU are not guaranteed phase coherent so you cannot use a pair to drive a pair of half-bridges and expect that it will behave properly as a full bridge. You can either use a full bridge with a single input, which will then give complementary drive, or you can use the approach we do where we sample the signal and then turn it into a pair of phase coherent signals which are not operating in full antiphase.
Hope this helps a little,
Pat.
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stevieturbo
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Re: PWM motor control ?
Primarily to control some 044's
Not fussed on staging them, would be quite happy to run 2 or 3 in parallel and ramp speed with load. 2 at present see around a max of 26A
So any drivers/boards/relays unless using 1 per pump would need to handle say 40A continuous when at max load.
Not fussed on staging them, would be quite happy to run 2 or 3 in parallel and ramp speed with load. 2 at present see around a max of 26A
So any drivers/boards/relays unless using 1 per pump would need to handle say 40A continuous when at max load.
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pat
- Syvecs Staff - Cleaner
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Re: PWM motor control ?
Stevie,
If you want to control a pair of 044s from a PWM output on the ECU then you'll need to use the Fuel Pump 1 output (which has PWM option) and then you'll need to buffer it externally since the outputs on the ECU won't like you drawing 40 odd amps. In essence you're driving a one way load and you can use a normal brushed DC driver for that, it doesn't need to be a half or full bridge. You should be able to find plenty of low side high current brushed DC drivers in the robotics and RC world.
That said, it may be simpler to just go with a bidirectional brushed DC motor ESC - you can get a 30A brushed motor ESC from HobbyKing for the outrageous price of five pounds and twenty one pence. I do not know how good they are, so I cannot vouch for whether they will work properly or not, but at a fiver to try it..... note that I did use an 80A brushless ESC from Turnigy that, after some period of running an EDF at half thrust, decided to start smoking.... we then swapped over to a spare Kontronic Jive I had, which predictably ran the EDF just fine, but then it did cost ten times as much, LOL. I guess you'de do fine with a Kontronic, Castle or Scorpion controller (assuming those guys do brushed controllers). They will all take a normal RC servo signal which is easy enougn to generate with an S6
"Neutral" is 1500uS (or 1540uS for you Futaba guys) so we set the PWM frequency to 333Hz and then run from 33% to 66% duty to get a 1ms to 2ms pulse every 3ms, easy Some controllers prefer a bit of a breather between pulses so you may need to slow it down to 200Hz and run 20% to 40% duty for a 1 to 2 ms every 5ms.
Hope this helps,
Pat.
If you want to control a pair of 044s from a PWM output on the ECU then you'll need to use the Fuel Pump 1 output (which has PWM option) and then you'll need to buffer it externally since the outputs on the ECU won't like you drawing 40 odd amps. In essence you're driving a one way load and you can use a normal brushed DC driver for that, it doesn't need to be a half or full bridge. You should be able to find plenty of low side high current brushed DC drivers in the robotics and RC world.
That said, it may be simpler to just go with a bidirectional brushed DC motor ESC - you can get a 30A brushed motor ESC from HobbyKing for the outrageous price of five pounds and twenty one pence. I do not know how good they are, so I cannot vouch for whether they will work properly or not, but at a fiver to try it..... note that I did use an 80A brushless ESC from Turnigy that, after some period of running an EDF at half thrust, decided to start smoking.... we then swapped over to a spare Kontronic Jive I had, which predictably ran the EDF just fine, but then it did cost ten times as much, LOL. I guess you'de do fine with a Kontronic, Castle or Scorpion controller (assuming those guys do brushed controllers). They will all take a normal RC servo signal which is easy enougn to generate with an S6
"Neutral" is 1500uS (or 1540uS for you Futaba guys) so we set the PWM frequency to 333Hz and then run from 33% to 66% duty to get a 1ms to 2ms pulse every 3ms, easy Some controllers prefer a bit of a breather between pulses so you may need to slow it down to 200Hz and run 20% to 40% duty for a 1 to 2 ms every 5ms.Hope this helps,
Pat.