CONTROL OF ALTERNATING CURRENT BATTERY HEATING USING IN-SITU MEASUREMENTS

A device for thermal control of a battery system includes a heating control module configured to generate an alternating current (AC) heating current and heat the battery system to a desired temperature by applying the AC heating current to the battery system over a selected heating time duration. The heating control module is configured to monitor a rate of increase of a temperature of the battery system during the applying, during the heating time duration, perform a periodic impedance measurement, the periodic impedance measurement including application of a measurement signal having a selected frequency range to the battery system for a measurement period, a length of the measurement period select to minimize a difference between a desired rate of increase and the monitored rate of increase, and adjust the AC heating current during the applying based on the temperature and the impedance measurement.