Wednesday, February 13, 2013

Source V0.0.6 posted

Tonight I posted version 0.0.6 of the source code (See tabs above).  This version has actually controlled the Kubota DC Generator   I have about 30 start/stop cycles on it, about 10x 'short' run (where the batteries were already mostly fully charged) and one medium size run where the batteries were about 150Ah down.

Combined with the latest hardware modifications (specifically the Stator sensing) , this release is perhaps the 1st complete one, in that it actually has made a run.  Some key features include:

  • Corrected major issue in Throttle Control where Watts were not always being recalculated, making the throttle control unstable.
  • Improved the start-up routine, making the Amps draw self optimizing for the starter and start-detected.
  • Refined all throttle timing values to better match my Kubota DC generator.  (These will need to be adjusted for each insulation using a different engine and/or throttle control module)

Two small features were also added:
  • Ability to re-purpose the Watermaker Clutch control line into a Co-Gen (heat extraction) pump line.  If this option is selected, a pump an be controlled for excessive heat extraction.  (and if an additional hardware expansion board is installed, both the Watermaker and Co-gen features can be supported).
  • Alternator PWM field drive can not back down based on Alternator and/or engine temperature   If one, or the other, gets too warm - system will reduce charging load.
  • Support for an optional NTC temp sensor on the FET heat-sink.    System will fault if FETs get too warm.
Over the next days / weeks I will be looking at the debug output files, and still thinking the PWM and perhaps the Throttle control logic is hunting a bit too much.

And here is a chart showing the longer run results.

Two things to notice:
  1. See how flat the Watts line is during Bulk phase?
  2. Likewise, notice how the Amps line drops during the Bulk Phase?

This is the result of the key goal for the project - maintaining a constant load on the driving engine.  As the battery voltage increases we need to lower the Amps delivered in order to maintain a constant Watts load delivered (and pulled)  from the Kubota engine.

One can also see the engine RPMs being managed - as the battery approached full charge, the amps dropped off quickly and the resulting load on the engine was reduce.  So we slowed the engine down.

Of concern to me is the large amount of hunting in the Field Drive during the Acceptance Phase.  I will be working on the algorithms to smooth this out.

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