Link to Previous Proposed Changes for Pre-Charge:
Link:
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
Depletion mode FET
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) [227.27V]
0.5A
Ratings at 60C
Controllable
Can close on-demand or
Closes when car close
Part Search
Implementation routes
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)
Types of relay
Solid-state relay
https://www.digikey.ca/en/products/detail/panasonic-electric-works/AQZ404/646386
AQZ404
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
Form B (Normally closed)
https://www.digikey.ca/en/products/detail/panasonic-electric-works/AQZ104/646370
AQZ104
400V and 0.6A (~0.4A at 60C)
https://www.mouser.ca/ProductDetail/Panasonic-Industrial-Devices/AQZ104?qs=wKtUvITRiakdB78b%2F5Uijg%3D%3D (Need to wait till August for parts to ship)
Form A (Normally opened)
https://www.digikey.ca/en/products/detail/panasonic-electric-works/AQZ206G2/9597209
AQZ206G2
600V and 1A (~0.6A at 60C)
Datasheet below
https://www.mouser.ca/ProductDetail/Panasonic-Industrial-Devices/AQZ206G2?qs=w%2Fv1CP2dgqpfmR1EUJ61AQ%3D%3D (Need to wait till September for parts to ship)
Form A (Normally opened)
Implementation plans
Existing parts
Remove
Charge pump and corresponding capacitors (C11, C12, C13, U4)
Series Resistor (R19)
Depends on parts
Pull-down resistor (R21)
Zener diode (D8)
Keep
LED and resistor (LED5 + R43)
Schematic
Q1 and Q2, replace with single relay
Cheaper ($12-16)
In stock
Current rating may not be enough at 60C
More Expensive ($30)
Have to wait
Enough current rating
Note: May not implement if not enough space
Q3, use relay (AQZ404) with series resistor
Needs to be done
If approved, should buy early
Pre-charge timing
Using 270 uF Cap MC
300 ohm
500 ohm
Out of stock IC
IC Load Switch
OOS
Alternative
CAN Controller
OOS
Alternative
CAN Reciever
OOS
Alternative
Optoisolator
Smaller changes (Check with)
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
Part List
AQZ404 (Solid State Relay)
Replaces Q3
Needs to be with series resistor
IC Load Switch
CAN Controller
MCP2515-I/P
HI-3111PSIF
MCP2515-I/SO
CAN Reciever
Optoisolator