Low cost fast charge contactor for high voltage battery management systems
A battery management system (BMS) connected to a battery having a positive end and a negative end, the BMS also connected to a fast charger. The BMS includes: a battery management controller protection circuit board (PCB) configured to manage an operation of the battery; a charger controller PCB configure to control fast charging of the battery; and a fast charge contactor positioned between one of the positive and negative ends of the battery and the fast charger. No fast charge contactor is positioned between the other of the positive and negative ends of the battery and the fast charger. The BMS is configured to determine a location of an isolation fault by connecting and disconnecting one or more resistors.
1. A battery management system (BMS) of a vehicle, the BMS connected to a battery having a positive end and a negative end, the BMS also connected to a fast charger, the battery powers a main load, the vehicle having a lockable charge port door, the BMS comprising:
a battery management controller protection circuit board (PCB) configured to manage an operation of the battery;
a charger controller PCB configure to control fast charging of the battery;
a first contactor positioned between a positive end of the battery and the main load;
a second contactor positioned between a negative end of the battery and the main load; and
a fast charge (FC) contactor positioned between one of the first contactor and the second contactor and the fast charger;
wherein the fast charge contactor is configured to disconnect the fast charger from the battery when the first contactor and the second contactor are both in closed state; and
wherein the BMS is configured to determine a location of an isolation fault by connecting and disconnecting one or more resistors.
2. The BMS of claim 1 , wherein the fast charge contractor is positioned between the positive end of the battery and the fast charger.
3. The BMS of claim 1 , wherein the BMS is further configured to determine that the FC contactor is welded.
4. The BMS of claim 3 , wherein the BMS is further configured to allow the charge port door to open if the FC contactor is determined not to be welded and keep the lockable charge port door closed if the FC contactor is determined to be welded.
5. The BMS of claim 4 , wherein determining whether it is safe to open the lockable charge port door is based on the location of the isolation fault.
6. The BMS of claim 1 , further comprising high voltage loads that need to be active when the lockable charge port door is open, on one of battery contactor legs with the fast charge contactor positioned on an opposite leg of the battery between the fast charger.
7. A method of determining whether to allow drive of a vehicle powered by a battery that is managed by a battery management system (BMS), the vehicle including a charge port door, which, when closed, prevents the vehicle from being charged, the method comprising: the BMS
receiving user input to put the vehicle in a drive mode;
detecting the battery being disconnected;
when a fast charge contactor positioned between the battery and a fast charger is not welded, connect the battery and put the vehicle in drive mode;
when the fast charge contactor is welded but the charge port door is closed, connect the battery and put the vehicle in drive mode; and
when the fast charge contactor is welded and the charge port door is open, cause the charge port door to be closed, and connect the battery and put the vehicle in drive mode after the charge port door is closed.
8. The method of claim 7 , wherein causing the charge port door to be closed comprising the BMS automatically closing the charge port door.
9. The method of claim 7 , wherein causing the charge port door to be closed comprising prompting the user to close the door via an infotainment system of the vehicle.
10. The method of claim 7 , wherein the fast charge contactor is positioned between the positive end of the battery and the fast charger and there is no fast charge contactor between the negative end of the battery and the fast charger.
11. A method of managing direct current (DC) charging of a vehicle powered by a battery that is managed by a battery management system (BMS), the vehicle including a charge port door, which, when closed, prevents the vehicle from being charged, the method comprising: the BMS
receiving user input to DC charge the battery;
detecting the charge port door closed;
when a fast charge contactor positioned between the battery and a fast charger is not welded, connect the battery, open the charge port door and allow DC charging of the vehicle;
when the fast charge contactor is welded but there is no isolation fault on opposite of the welded fast charge contactor, open the charge port door and allow DC charging of the vehicle; and
when the fast charge contactor is welded and there is an isolation fault on opposite of the welded fast charge contactor, keep the charge port door closed to prohibit DC charging of the vehicle until the isolation fault is resolved or the fast charge contactor is no longer welded.
12. The method of claim 11 further comprising providing a warning to the user via an infotainment system of the vehicle that it is unsafe to charge the vehicle if the fast charge contactor is welded and there is an isolation fault on opposite of the welded fast charge contactor.