Charge Pump
This project has been discussed here: https://www.openinverter.org/forum/viewtopic.php?f=7&t=82
The goal is a device with 2 functions:
- Boost the voltage from a LV battery into the cars HV battery
- Buck the voltage from rectified AC into the LV battery
The hardware basis is a regular bi-directional DC/DC converter. So one half bridge module with an inductor connected to its output and filtering caps on input and output.
The output bridge would be connected to PWM channel 1. The il1, il2, tmphs input will be used as is. The main input pins are remapped:
| Pin | Name |
| 1 | - |
| 2 | - |
| 3 | - |
| 4 | - |
| 5 | - |
| 6 | LV battery voltage via isolator module |
| 7 | Enable input (12V) |
| 8 | HV battery voltage via isolator module |
| 9 | - |
| 10 | - |
| 11 | Tie to 12V |
| 12 | LV contactor output (open collector 1A) |
| 13 | Mode select boost (12V) |
| 14 | AC contactor output (open collector 0.5A) |
| 15 | Mode select buck (12V) |
| 16 | HV contactor output (open collector 0.5A) |
| 17 | Emergency Stop (12V, PWM inhibit when low) |
| 18 | Temperature PWM output (open collector 0.5A) |
| 19 | BMS Over/Under Voltage input (12V) |
| 20 | LV/HV Output (open collector 0.5A) |
| 21 | - |
| 22 | - |
| 23 | GND |
| 24 | Vcc (7-26V) |
| 25 | CANL |
| 26 | CANH |
Mode of operation
Any operation is inhibited until the enable input on pin 7 goes high. The mode of operation is then selected using pin 13 or 15.
Boost mode
Boost mode is started by enabling pin 13. The LV side is precharged to a given voltage. When done, both LV and HV contactors are closed.
Boosting starts BELOW a specified minimum voltage on the HV side. The boost current is ramped up the lower the voltage on the HV side becomes until it reaches a configurable maximum. Boosting stops ABOVE a specified hysteresis voltage.
Boosting also stops when the LV side voltage drops below a given minimum. If the floating voltage of the LV side remains below a given hysteresis value boosting will not start.
Boosting also stops when pin 13 or pin 7 go low. Also BMS input, or does BMS just cut the enable signal?
Buck mode
Buck mode is started by enabling pin 15. The HV side is precharged to a given voltage. When done, the LV and AC contactors are closed.
Current is ramped up to a given maximum until a threshold voltage is reached, then buck mode switches to voltage regulation (like a lab power supply). At a given cutoff current buck mode is stopped (like a charger).