Author Topic: DIY genset controller.  (Read 11092 times)

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Offline rossw

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DIY genset controller.
« on: January 20, 2012, 03:20:34 pm »
When I moved in to my new place, I'd hoped to install a commercial CHP unit (Combined Heat and Power) - but suppliers and circumstances conspired against me and I ended up building my own instead. I also had to build something to handle the starting, stopping and monitoring of the engine etc.

Without having finished the genset itself, there was a lot of guessing what I might need. And without the inverter, or having lived in the place, I had no real idea what I needed, what timings might be etc. So it was all "seat of the pants" stuff. A few ideas I did have were that I wanted it to keep track of the run-hours so I'd know when to change the oil at least!

So I picked a suitable processor of the day and set about making a prototype. I intended to make a proper one once this had run for a while and I knew what else I really needed it to do. Well, that was 7 years ago, and the prototype is still running...

I  built it on veroboard - doesn't everyone do prototypes this way? I don't usually use sockets, but I figured that this thing might be easier if I could drop out a chip and replace it with one with a different version of the code. (As I built it, I added an in-circuit programming connector, so I never ended up popping the chip either)


The underside is a mess. But it worked.


When completed, the top of the board looked pretty messy too


I poked it into a box along with the display and a switch to select auto/manual(stop)/manual(run)


Bit of a squeeze.


It mounts on the genset frame, along with the fuse and relay panel, governor and AFR controller.


Typical displays (it cycles through several)


The cold sensor wasn't connected on this photo, but has been ever since.




The controller monitors engine temperature in several places, RPM and alternator frequency, oil pressure and inverter signals to request start/stop. It also controls the (electric) water pump, which runs whenever the engine is running, and continues to run while the system can extract useful heat from the engine and/or exhaust. It controls the governor for speed control, does all the cranking control, will attempt a start only (x) times. Will lock-out if there's a problem. Calls for help if the temperature is getting high for any reason, and shuts down if it gets over-temperature or low oil pressure, or the engine RPM is too high or low.

On shutdown it drops the load, then throttles down to idle and has a 30-second cool-down before turning off.

Does other things too that I can't remember now - it just sits there and does its job. If you've got any questions, just ask. I'm sure I'll know (or can check the code to remind me!)

Offline wdyasq

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Re: DIY genset controller.
« Reply #1 on: January 21, 2012, 07:23:05 am »
Does it come in blue? Or, only in black?


Ron

Offline tomw

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Re: DIY genset controller.
« Reply #2 on: January 21, 2012, 08:19:56 am »
Does it come in blue? Or, only in black?


Ron

I know Texas is a bit behind the times but they make this stuff called paint now and it comes in millions of colors. ;D 8)

Tom
Do NOT mistake me for any kind of "expert".

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Offline Watt

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Re: DIY genset controller.
« Reply #3 on: January 21, 2012, 01:09:30 pm »
Does it come in blue? Or, only in black?


Ron

I know Texas is a bit behind the times but they make this stuff called paint now and it comes in millions of colors. ;D 8)

Tom

Is that stuff called paint transparent? 
CEO of this Dis-Organization....

Offline Burnit0017

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Re: DIY genset controller.
« Reply #4 on: January 21, 2012, 06:17:18 pm »
Wow, very nice. Do you have photos of the sensors?

Offline rossw

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Re: DIY genset controller.
« Reply #5 on: January 21, 2012, 06:21:19 pm »
Wow, very nice. Do you have photos of the sensors?

Which sensors?

Lemme have a look at the pics and see... I probably don't actually.

Offline rossw

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Re: DIY genset controller.
« Reply #6 on: January 21, 2012, 06:43:32 pm »
The alternator is still attached to the engine here (it was removed before I finished, it never actually ran - there is no fan belt, no mechanical water pump - nothing off the front of the engine at all).

The oil pressure sensor is shown here in the centre of the screen. I removed the normal "idiot light" pressure switch and replaced with this analog sensor.


You can see one of the two hot water sensors here in the thermostat body, there is another on the other side (before the thermostat itself) but it is obscured by the 1.25" barb for the radiator hose.  (You can see the red wire going to it though)
You can also see the magnetic pickup for the speed sensor, the long all-thread looking thing at about 10 oclock on the flywheel.


I can't find a picture of the cold sensor. It is just a thermister strapped firmly to the copper pipe of the return water. The whole lot is then lagged (thermally insulated).

Since I built this, I've added another batch of logging, and plumbed in additional pumps and valves, so my wood fired boiler can contribute heat in the winter. I used DS18B20 sensors in stainless steel cans for an additional bunch of sensors. Will go take some extra pictures if you're keen on knowing more?  I now also monitor the exhaust (after heat-exchanger) temperature, cold water, warm water (after the exhaust heat exchanger), hot (flow to tanks), cold to and hot from the boiler, air temperature and a couple of other things. In time, I will probably re-build the genset controller using more modern sensors and hopefully eliminate some of the noise that seems to plague normal "automotive" grade sensors.

Offline ghurd

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Re: DIY genset controller.
« Reply #7 on: January 22, 2012, 07:09:49 am »
All of a sudden my design for a "battery voltage based, speed controller for a lawn mower engine powered battery charger" looks a little obsolete.

But it is going to have LEDs light up, and be chrome plated
Always works better if chrome plated with blinky lights. ;D
G-

Offline Wolvenar

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Re: DIY genset controller.
« Reply #8 on: December 06, 2013, 11:34:33 pm »
So ghurd, were you still planning that flashy lights small gen control ?
Trying to make power from alternative energy any which way I can.
Just to abuse what I make. (and run this site)