Standardize power path current draw conventions

[ducky64]

Standardize conventions defined in the Buck/BoostConverterPowerPath: switch on buck is an VoltageSink that draws the average inductor current, and switch on the boost is a VoltageSource that provides the max average output current. Refactors the BuckBoostConverterPowerPath to use this convention. This isn't the cleanest, but this allows these parameters to propagate to the connected device (eg, buck converter controller IC's power-in pin) through the connection instead of needing to be plumbed explicitly. This makes the custom discrete converter a bit tougher, but probably a good trade-off.

Additional fixes:

• current limit on the boost power path, accounts for the boost ratio properly.
• account for efficiency factor on current draw for buck and boost converters
  • updates examples to tolerate this
• plumb rds_on through the custom converters
• model switch current limits in custom converters (generally not the limiting factor, but still good practice)
  • add ForcedVoltageCurrentLimit as a library block
• unit tests that run the buck and boost converter power path and check generated parameters

Adds the actual inductor current peak for all converter power paths. Makes the discrete custom buck converter use this, instead of calculating it independently.

Resolves #406 and #307

TODO

• account for switch limits in custom power converter output current limit
• end to end block unit testing

[Copilot]

Pull Request Overview

Standardizes current draw conventions for buck/boost converter power paths, adds inductor current peak tracking, fixes boost current limits and efficiency factors, and ensures rds_on is passed to FET blocks.

• Adopt buck switch as a VoltageSink drawing average inductor current and boost switch as a VoltageSource providing max average output current
• Introduce actual_inductor_current_peak everywhere and refactor chains to use it for FET sizing
• Correct boost limit calculation (ratio and efficiency) and propagate fet_rds through custom converters

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
edg/parts/FanConnector.py	Updated comment to reflect correct startup duration and steady-state current draw
edg/parts/BuckConverter_Custom.py	Plumbed rds_on into FetHalfBridge, renamed force ports, switched to peak current
edg/parts/BuckBoostConverter_Custom.py	Added VoltageSourceConnector, removed voltage_drop, refactored chain logic
edg/abstract_parts/AbstractPowerConverters.py	Updated port types/comments, added actual_inductor_current_peak, adjusted connects

Comments suppressed due to low confidence (3)

edg/parts/BuckConverter_Custom.py:41

• [nitpick] The forced-chain variables mix pwr_in_force with sw_out_force. Consider using a consistent prefix/suffix (e.g., sw_in_force/sw_out_force or pwr_in_force/pwr_out_force) to improve clarity.

(self.pwr_in_force, ), _ = self.chain(  # use average current draw for boundary ports

edg/abstract_parts/AbstractPowerConverters.py:396

• The new actual_inductor_current_peak parameter isn’t covered by existing tests. Add unit tests to verify it’s computed correctly and propagated to downstream blocks.

self.assign(self.actual_inductor_current_peak,

edg/parts/BuckBoostConverter_Custom.py:22

• [nitpick] This docstring is ambiguous: the connector uses VoltageSink ports on both sides. Clarify that it links a source port to a sink port and update parameter descriptions accordingly.

"""Connects two voltage sources together (inductor output to FET center 'source')."""

[Copilot]

[nitpick] Passing Range.all() as a placeholder argument is confusing. Consider overloading VoltageSinkConnector/VoltageSourceConnector or providing a named constant to make intent explicit.

Suggested change

	Range.all(), # unused, port actually in reverse
	UNUSED_CURRENT_LIMIT, # explicit placeholder for unused current limit