...

Power Stage

Function

Array configuration

Seems boost only MPPTs are sufficient for MS15, as even with the lowest battery pack voltage the boost ratio is at the minimum of 1.1. It is possible for Vmpp to be slightly higher if the irradiance is above 1000W/m2, but I don’t think that’s too much of a concern.

Since pack voltage can’t go any higher (limited by motors), a buck-boost topology will be needed for MS16 since array area is increasing to 6m2, or the array will need to be split into 3 strings.

Topology

Since we only need boost mode for now, we will stick with that as it is the simplest option. The same controller can be used in a SEPIC configuration if step-up/down is desired in the future.

Primary FETs

GSFN6982 Good-Ark Semiconductor | Discrete Semiconductor Products | DigiKey

...

Expand
title Gate Charge Loss

Other things we need:Spreadsheet with component specs: View filenameTPS4306x_BOOST_CALCTOOL_REVB.xls

• Inductor: AGP4233-473ME (100khz) or -683 (50khz), larger

  • Lower frequency → higher efficiency (less switching loss), more mass (larger coils)

• Other simpler components in spreadsheet, seem feasible.

• ~4 mOhm at 7.5V

Current Progress:

MPPT with output regulation:

updated preadsheet with boost converter specs:

To investigate: not using a multiplier

• Potentially via output current sensing?

  • Battery should keep (in a short timeframe) stable voltage, so sensing the output current would give us a proxy for power

Next steps:

Create schematic