BUS LEAKAGE RESISTANCE ESTIMATION FOR ELECTRICAL ISOLATION TESTING AND DIAGNOSTICS

摘要

Electrical bus isolation is detected for an electrified vehicle having a DC power source connected to positive and negative buses. The positive bus is connected to chassis ground, and a resulting first current is sensed that flows through a negative bus leakage resistance and a balanced leakage resistance. The negative bus is connected to chassis ground, and a resulting second current is sensed that flows through a negative bus leakage resistance and a balanced leakage resistance. The positive and negative bus leakage resistances are estimated in response to respective ratios of the first and second currents. An isolation value is compared to a threshold, wherein the isolation value is responsive to a voltage of the DC power source and a smaller one of the positive and negative bus leakage resistances. An atypical isolation is signaled when the isolation value is less than the threshold.

主权项

1. An electrified vehicle comprising:
a positive bus connectable to a positive output of a DC power source; a negative bus connectable to a negative output of the DC power source; a chassis ground distributed within the vehicle; a first detector circuit selectably activated to i) connect a first fixed resistance between the positive bus and chassis ground and ii) sense a resulting first current flowing through a negative bus leakage resistance and a balanced leakage resistance; a second detector circuit selectably activated to i) connect a second fixed resistance between the negative bus and chassis ground and ii) sense a resulting second current flowing through a positive bus leakage resistance and the balanced leakage resistance; and a control circuit identifying the positive and negative bus leakage resistances in response to respective ratios of the first and second currents.