OBC/CCS System block diagram

[sirpewe]

Hi.
Need some feedback/comments for my design.
I have a foccci board that shall handle CCS charging and CP-signal.
FOCCCI will communicate via CAN to a raspberry PI which handles communication to OBC.
The RPI will also communicate to FOCCCI and send battery voltage and allowed charge current (based on battery temperature and voltage).
The RPI will also generate PWM signal (via a custom PCB) to the OBC based on can info from FOCCCI.
The CAN will most likely not be as pictured but instead CAN0 will be connected to FOCCCI and OBC and CAN1 will be connected from RPI to CAR-CAN (vehicle can).
My main concern/question is regarding "high voltage" connections (but other comments is also welcome).
1. Is it ok to only have one contactor for "Battery -" that is enabled when charging (and when operating)?
2. Do I need a separate contactor for the OBC to battery, or can the positive be connected directly to battery and only disconnected via "Battery -" contactor? -this will make is connected during CCS charging also, is this ok?
3. Do I need relays/contactors for AC side to OBC or is this included in the charger itself? (I will use a mitsubishi OBC).

Thank you.

BMW_HV_SYSTEM.pdf

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[tom91]

1. You need 2x contactors for your CCs port, dedicated ones.
2. You need to control your HV bus somehow, currently you have drawn an Inverter doing two contactors. This wont work for charging.
3.AC is direct to charger as shown.

What are the other components planned in your system?

Which inverter and motor?
which DCDC?
Which Charger?
Which BMS?

[sirpewe]

Thank you for quick response.
1. Today the inverter controls the positive contactor (and precharge) and the negative is controlled from ignition button.
(Maybe need to clarify in diagram).
2. I have tesla LDU as motor and Tesla M3 LR battery. Car has been operating with tesla's PCS but I have issues with charging not working every time and also DC/DC intermittent operation. So I will change to the Mitsubishi OBC (and DC/DC) for this.
3. BMS I plan to use the existing in the Tesla and I hope to be able to read out the cell voltage and temperature via CAN (need to verify this).

BR
// Per