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DescriptionPower Distribution
Target releaseMSXIV
Epic

HW-234 - Getting issue details... STATUS

Document owner

Josh Rong

Project leadsJosh Rong
Team membersAashmika Mali Arshan Khanifar Micah BlackJosh Rong

Goals

  • Distribute power to all components with maximum efficiency
  • Reliable operation

Background and strategic fit

A power distribution board is necessary to supply power to the various subsystems in the vehicle. This board performs distribution, startup, shutdown and emergency shutdown as required in regulations. In addition to supporting powering the boards, it also powers components directly, such as the horn, camera and others. 

Requirements

#TitleUser StoryImportanceNote
1DC-DC
  • Convert ~150V to 12VDC at up to 30 A
Must have
2Thermal Control
  • Control temperature of the DC-DC for reliable operations
Must have
3Rear Power Distribution
  • Distribute power to system located closer to battery box
  • Power Path IC will protect the system from under and over voltage
Must have
4Front Power Distribution
  • An extension to Rear Power distribution to distribute power in front enclosure
Must have
5Aux Charger
  • When DC-DC is used as power source it will also charge the AUX battery
Not urgent
6Protection
  • Fuses are implemented for all power channel
  • Over-current protection compactor is there for AUX
Must have

Power State

It is best to imagine there are two state the power distribution boards can be in, one for car start up/emergency stop, and one for drive.

During start up or emergency stop the car's LV(low voltage) systems is powered off of an auxiliary battery, in this state only some system are allowed to be powered ie: BMS, rear light, and driver control. Only a limited system are allowed to be powered is to reduce power loss on the aux battery. Note that in this state the main battery relay are open, meaning that no HV(high voltage) devices are operating. 

During drive the car's LV systems is powered off of DC-DC, in this state all system are powered.


Power Path Select

[Under construction]

Firmware

Power distribution is divided into two parts: Front Power Distribution and Rear Power Distribution,

Modules that are shared between Front and Rear:

  • Lights

Modules only needed by Front:

Modules only needed by Rear:

  • BMS Carrier
  • Motor-Controller Interface / Pre-Charge
  • DC-DC 

Notes:

  • The modules that are shared between front and rear will still be implemented as separate modules in the Front and Rear projects, however there will be a shared module that will take input from Front/Rear that will control which switches are used
  • Each module will create an event when they are ready to turn a switch that will be read by MCP 23008's driver that has a lookup for the switches and will write to the corresponding address to flip the switch
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