PDU (Power Distribution Unit) Design

Aptera Community Aptera Discussions PDU (Power Distribution Unit) Design

Aptera Community Aptera Discussions PDU (Power Distribution Unit) Design

  • PDU (Power Distribution Unit) Design

  • Brad Renninger

    Member
    January 25, 2023 at 8:57 am

    This is the Block Diagram for the PDU (Power Distribution Unit)

    Looks like we have one low voltage connector and 10 high voltage connectors +1 DCFC connector. So that would mean they have 12v and a 400v (300v?) components.

    The 12v input seems to power the entire module. It also handles the HVIL (High voltage interlock) and would cut the contactors. It seems the HVIL detects disconnections of the connectors and a Lid detection. The HVIL loop goes out to the LV connector so there are likely external interlocks also considered by the system.

    Unlike all other connections the wheel motor inverters are unfused as is the DCFC connector. They may be fused with a non-user replaceable fuse. But at least the wheel inverters and the DCFC plug have their own contactors and there is a pyro fuse on the +side of the battery.

    The battery has independent/dual serial communications with the battery (MMB IsoSPI)

    What is missing from this diagram is where the AC rectifier is. You can see the DCFC (300-400v) connector is separate from the OBC/DCDC (A/C Rectifier). I am assuming the listed DCFC connector in the diagram is only the one on the PDU and not the actual Tesla plug at the back of the car. This may be what they need to work on now that they agreed to put DCFC on the LE. With only L1 and L2 charging you just need a rectifier and the wiring to get to the PDU. Now you need significantly heavier wiring and a way to switch over from AC to DC charging.

    One question I have is why do they have a bypass (Contactor P) and in inline contactor (5) on the high voltage negative side? Could it have to do with the solar charging?

  • Dennis Swaney

    Member
    January 25, 2023 at 9:14 am

    In addition I only see two connections for solar panels while there are a maximum of 4: Nose, Dash, Roof, & Hatch. I’m guessing that each connector will handle two panels in parallel. Possibly Solar 1 Connector will handle the basic Dash & Roof panels with Solar 2 left available for the optional Nose & Hatch panels. Though the basic two could also be split between Solar 1 & 2 with the optional two also being split between the Solar Connectors as electrically there isn’t any difference between the possible usage.

    Regarding the bypass circuit, any possibility it is to limit current when more that the basic two panels are used? With two panels the direct route is used; with more than two panels the direct route is severed and the resistor route is used.

    Oops, just noticed that connection T is part of a temperature circuit, so if the temps get too high, then maybe the current flow is shunted through the resistor?

    • This reply was modified 5 days, 17 hours ago by  Dennis Swaney.
    • This reply was modified 5 days, 17 hours ago by  Dennis Swaney. Reason: Added temperature circuit query
    • Brad Renninger

      Member
      January 25, 2023 at 9:28 am

      Hood has 30 cells, Dash has 20, Roof has 50, and Trunk has 93. Could they have Hood/Dash/Roof on 1 connector for a total of 100 @363w. And have the hatch/trunk on another for a total of 337w? I dunno.

      Could all the panels be on one connector and the second for an external spare? Maybe but I doubt it.

      Or… Going with what you said, but putting a different spin on it. Is one connector for the built in Panels (Roof/Dash) and one connector for the optional panels (Hood/Trunk)

  • Olivier Laroque

    Member
    January 26, 2023 at 1:32 pm

    Hi Guys,

    Where do you assume the V2x could go out ? Do we have any data about the possible output power ?

    • Brad Renninger

      Member
      January 26, 2023 at 2:33 pm

      From the DCFC it looks like they have 7, TE 2103124-1 connectors on the PDU. 4 larger TE 2141227-3, and the LV connector of unknown manufacture.

      I am going to guess the 4 larger connectors are for the 3 wheel motor inverters and 1 for the DCFC.

      The 7 smaller ones are for the HVAC, Cabin Heater, Batt heater, OBC/DCDC, Solar 1 and Solar 2…

      Just to note. In the video the mock up has two of the smaller ones missing and one larger as opposed to the CAD drawing they show.

      So…… Why are there 7? What is the last connector for? In the block diagram I don’t see any unaccounted for connector positions. Is the diagram older or newer than the CAD model? And that connector is a 40a connector, which at 300v is 12Kw. Could it be for V2L or V2G in the future? Dunno.

  • Brad Renninger

    Member
    January 27, 2023 at 7:54 am

    Looks like, from the AOC youtube channel interview with Chris Anthony a few minutes ago. There will be an option for an inverter option down the road. There is also no V2G yet, or planned.

  • Conor Vogt

    Member
    January 27, 2023 at 12:29 pm

    The “P” bypass loop is a pre-charge contactor. There’s a resistor in that loop to limit the in-rush current when the main contactors close. It allows the capacitors in the inverter and other modules on the HV line to charge up to the same voltage as the battery pack much slower.

    This prevents arcing on the main contactors which can weld them shut. The arcing, if it does not weld the contactors closed, will cause increased contact resistance on the contactor and thus increased losses and temps which are dangerous and could lead to fire if left unchecked.

    • Dennis Swaney

      Member
      January 27, 2023 at 1:09 pm

      So there is a switch or relay at #5?

  • Brad Renninger

    Member
    January 27, 2023 at 6:12 pm

    Awesome info Conor thanks! By main do you mean 4p and 4n?

    Also would you have any insight why they would gang 4 outputs onto one contactor (2) and the solar onto another (3)? Simplicity?

    And Denis 5 is a contactor. Like a relay but the coil power is isolate from the switched power. So they are probably 12v contactors switching on the 300v.

    • Dennis Swaney

      Member
      January 27, 2023 at 6:42 pm

      Brad, I’ve installed many small relays that fit your description of the contactor with the coil and switched contact(s) being separate circuits for example air horns in my cars. The coil was in the horn button circuit (12 vdc from fuse panel) while the NO contacts carried 12vdc directly from the battery (with an inline fuse. It looks like the term relay is only used for power circuits up to 250V while the term contactor is used above 250V to 1000V. BTW, my original job in the USAF was radio repair back in the vacuum tube era.

      Oh, any way you could post the legend for the block diagram showing what each number and letter stands for?

    • Conor Vogt

      Member
      January 29, 2023 at 8:58 am

      <div>When I say main I mean contactors number 1 and 5. Those are the main connection points to the power inverter modules from the battery.
      </div><div>

      4p and 4n are the positive and negative DCFC contactors. Those only close when DCFCing and are normally open otherwise.

      My educated guess for splitting solar and HV non-inverter loads between contactor 2 and 3 is to reduce idle consumption and energy waste from the solar inverters in low/no solar conditions.

      Solar inverters are not 100% efficient and the hardware still has idle consumption when turned on. If you’re driving at night or there’s very little sun outside, the idle consumption of the inverters can exceed the production from the panels and then you’re just wasting energy for nothing. The contactor gives Aptera the control to shut the inverters off in those low/no solar conditions to save battery energy.

      </div>

  • Brad Renninger

    Member
    January 27, 2023 at 7:13 pm

    Hmm Interesting.

    So you know a lot of this stuff too. I had always thought a contactor was deigned so you would never have a common between the load and the coil. Hence the coil is on a 9-36v circuit and the load is high voltage or something. On a relay you can use, say 12v neg for the coil and load whether that be in the relay or somewhere else.

    I do not have a legend. But there is some color/shape consistency. Contactors are all numbered blue circles. Im gonna have to look through more Aptera vids to see what else I can find.

    • GLENN ZAJIC

      Member
      January 27, 2023 at 9:15 pm

      I love that there are so many knowledgeable people on this forum!

    • Dennis Swaney

      Member
      January 28, 2023 at 7:12 pm

      I’m wondering if the numbered contactors are just arbitrarily numbered 1 through 5 or if there is more info describing each one. I suspect that #4 is at least a dual since there is a 4 positive and a 4 negative. The “T” & “V” are obviously temperature and voltage sensors since they lead back to blocks labeled as such on the Battery Management System

      • Brad Renninger

        Member
        January 29, 2023 at 9:04 am

        NACS uses the same pins for DC or A/C. So 4p and 4n allows for the bypass to the Rectifier. Look up Technical Specification TS-0023666 and go to section 4. 4p and 4n corresponds to K3 and K4 on that diagram. I don’t see the signal “Control Pilot” pins or the ground on the Aptera diagram.

        • Dennis Swaney

          Member
          January 29, 2023 at 12:43 pm

          Wouldn’t the Ground pin be attached to the grounding which is apparently the heavy black line?

          • Brad Renninger

            Member
            January 29, 2023 at 2:32 pm

            I combed through the Tech spec and it looks like the ground is an earth ground/chassis ground for another isolation module and vehic controller. It’s not connected to the Neg. It’s more like a reference common vs a return common.

            But then does the onboard Rectifier not need a ground? These pins being able to switch from A/C to D/C is nuts.

            • Dennis Swaney

              Member
              January 29, 2023 at 4:14 pm

              I’ve found that many times critical info is in the full circuit schematic but not shown in the more simple block diagram.

  • Robert Acevedo

    Member
    January 28, 2023 at 2:34 pm

    Where is this picture from?

    • Brad Renninger

      Member
      January 28, 2023 at 4:39 pm

      It’s from their official video on the DC fast charge announcement.

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