Pre-Charge [MSXV]

Link to Previous Proposed Changes for Pre-Charge:

Link:

Changes for MCI Rev 2.0

New Suggestions

• Motor controller capacitors are currently charged with a constant voltage source and series resistor. This is always 50% efficient. For a challenger vehicle, it might be better to have a switching circuit (buck topology) to charge with constant current (which would also be faster).

• Keep to 12V by removing DC DC inversion

• Add hall effect sensor

• Make simpler by removing irrelevant portions (e.g. fan control and thermistor may have been exclusive to MOV since shorts less of an issue?)

Research Summary

• Simplify Charge Pump and Depletion Mode FET (U4)

  • Original parts

    • Charge pump switch regulator

      • https://www.digikey.ca/en/products/detail/microchip-technology/tc7662beoa713/418710

    • Depletion mode FET

      • https://www.digikey.ca/en/products/detail/ixys/ixth6n50d2/2183273

  • New Change

    • Find closed switch to replace the two components

    • Part requirement

      • Normally closed relay

        • Form B (Form C can work)

        • https://forum.digikey.com/t/understanding-form-a-form-b-form-c-contact-configuration/811

      • Support

        • 151.5V + safety factor (x1.5)

        • 0.5A

        • Ratings at 60C

      • Controllable

        • Can close on-demand or

        • Closes when car close

  • Implementation

    • Existing parts

      • Remove

        • Charge pump and corresponding capacitors

        • Pull-down resistor

      • Keep

        • LED and resistor

        • Current limiting resistor

    • Relay

      • For lower current parts

        • Add a series resistor to discharge path for lower current

        • Drawback

          • Slower to discharge (0.25s)

      • For lower voltage parts

        • Use relay in parallel

        • Less preferrable

        • Drawback

          • Expensive

          • May not share load equally (reduce one relay lifespan quicker)

    • Schematic

      • Q1 and Q2, use relay (AQZ204) with series resistor

      • Q3, use relay (AQZ404) with series resistor

  • Part Search

    • Types of relay

      • http://www.electricalterminology.com/types-of-relays/

      • https://www.electronicshub.org/classification-of-relays/

    • Solid-state relay

      • https://www.digikey.ca/en/products/detail/panasonic-electric-works/AQZ404/646386

        • 400V and 0.5A (0.3A at 60C)

        • Datasheet below

        • https://www.mouser.ca/ProductDetail/Panasonic-Industrial-Devices/AQZ404?qs=Wn4D5qJAqBJmKpb9gy8Awg%3D%3D (mouser link)

        • Need lower current part implementation

      • https://www.digikey.ca/en/products/detail/ixys-integrated-circuits-division/CPC1705Y/7776155

        • 60V and 3.25A (2.5A at 60C)

        • Need lower voltage parts

        • Current amount a little overkill

• Smaller changes

  • Removing:

    • Fan control

      • Remove fan connector

      • Remove entire fan control sheet

    • Thermistor

      • Remove thermistor connector

      • Remove entire thermistor sheet

  • Add jumpers near AND gate to skip it