Patent ID: 9046559
Filing Date: 2015-06-02
Classification: B60L,G01R,Y02T

Abstract:
1. An isolation monitor for an electric vehicle having a battery pack, comprising: a controller monitoring an isolation voltage between a power circuit in a high voltage circuit portion powered by the battery pack and a chassis of the electric vehicle; a switchable bias voltage module applying a switchable DC bias voltage between at least one DC battery voltage sense line of the power circuit and a chassis during one or more isolation monitoring periods wherein the switchable bias voltage module comprises a switchable voltage divider that includes a first switchable path having a first switch with a first series resistor to couple the chassis ground to a first DC sense voltage line of the power circuit in a first portion of a monitoring cycle and a second switchable path having a second switch with a second series resistor to couple the chassis ground to a second DC sense voltage line of the power circuit in a second portion of a monitoring cycle; and the isolation monitor configured to monitor an isolation voltage having a first known value in a first portion of a monitoring cycle when there is no electrical fault and a second known value in a second portion of the monitoring cycle when there is no electrical fault and determine whether there is a fault and a fault location based on monitoring changes in the isolation voltage in the first portion of the monitoring cycle and the second portion of the monitoring cycle.