High voltage battery capacitor bank and mid-bus pre-charging using a lower voltage battery

A method comprising:

• receiving an indication to pre-charge a high-voltage DC bus;
• transferring power, using a DC-DC converter, from a low-voltage DC bus to the high-voltage DC bus while a high-voltage battery is not coupled across the high-voltage DC bus to pre-charge a capacitor connected across the high-voltage DC bus, wherein:
• the low-voltage DC bus is connected to a low-voltage battery;
• the DC-DC converter is configured to transfer power based on a control signal;
• the control signal causes a current draw of the low-voltage battery to increase up to a maximum current value;
• and
• the maximum current value corresponds to a predetermined drop in voltage of the low-voltage DC bus;
• and
• causing a contactor, arranged between the high-voltage DC bus and the high-voltage battery, to close to connect the high-voltage battery across the high-voltage DC bus after pre-charging the capacitor.

A method comprising:

• causing a first DC bus, while a high-voltage battery is decoupled from the first DC bus, to be pre-charged by a low-voltage battery using a first DC-DC converter coupled between the first DC bus and the low-voltage battery;
• causing a second DC bus to be pre-charged using a second DC-DC converter coupled between the first DC bus and the second DC bus;
• and
• causing an AC bus to be pre-charged, while an AC contactor coupled between the AC bus and an AC system is open, using a DC-AC converter coupled to the second DC bus and to the AC bus.

A system comprising:

• a high-voltage battery;
• a DC-DC converter connected between a low-voltage DC bus and a high-voltage DC bus;
• a low-voltage battery configured to be connected and disconnected from the low-voltage DC bus;
• a capacitor connected across the high-voltage DC bus;
• a contactor configured to connect and disconnect the high-voltage battery from the high-voltage DC bus;
• and
• control circuitry configured to:
• receive an indication to pre-charge the high-voltage DC bus;
• cause the DC-DC converter to transfer power from the low-voltage DC bus to the high-voltage DC bus while the high-voltage battery is disconnected from the high-voltage DC bus to pre-charge the capacitor in response to the indication;
• and
• close the contactor to connect the high-voltage battery across the high-voltage DC bus after the capacitor has been pre-charged.