Patent ID: 11970072
Assignee: GM GLOBAL TECHNOLOGY OPERATIONS LLC
Field: Transport (Mechanical engineering)
Classification: CPC B  H | IPC B  H

Claim 0:
1. A vehicle electrical system, comprising:
a rechargeable energy storage system (RESS) having a first voltage;
a power inverter electrically connected to the RESS;
an electric motor having a plurality of machine windings with each of the machine windings including a polyphase terminal electrically connected to the power inverter, and the electric motor further having a neutral terminal separate from the polyphase terminals; and
an accessory load selectively connected to one of the RESS and the neutral terminal of the electric motor, with the accessory load requiring a second voltage;
a first accessory load switch disposed between the neutral terminal of the electric motor and the accessory load;
a second accessory load switch disposed between the RESS and the accessory load;
wherein the power inverter includes semiconductor switches S1, S3, and S5 each disposed between the RESS and a corresponding one of the polyphase terminals, and includes semiconductor switches S2, S4, and S6 each connected between the accessory load and a corresponding one of the polyphase terminals, wherein the semiconductor switches S1-S6 cooperatively convert direct current (DC) power from the RESS to alternating current (AC) power for powering the electric motor via high-frequency switching;
wherein the power inverter is configured to cycle between:
a first operational state where the power inverter connects the RESS to the plurality of machine windings of the electric motor such that current flows from the RESS through the polyphase terminals to the accessory load via closing the first accessory load switch, opening the second accessory load switch, closing one of the semiconductor switches S1, S3, and S5 and opening the remaining semiconductor switches S1-S6;
a second operational state where the power inverter disconnects the RESS from the plurality of machine windings of the electric motor and interrupts current to the machine windings, such that the power inverter steps down the first voltage of the RESS to the second voltage of the accessory load, via closing the first accessory load switch, opening the second accessory load switch, opening the semiconductor switches S1, S3, and S5 to disconnect the RESS from the polyphase terminals, and closing one or more of the remaining semiconductor switches S2, S4, and S6 to allow current to flow from one or more of the polyphase terminals to the accessory load; and
a third operational state where the RESS directly charges the accessory load without stepping down the voltage via opening the first accessory load switch and closing the second accessory load switch.