Control of alternating current battery heating using in-situ measurements

A method of thermally controlling a battery system of a vehicle, comprising:

• controlling a heating control module to generate an alternating current (AC) heating current;
• heating the battery system to a desired temperature by applying the AC heating current to the battery system over a selected heating time duration;
• monitoring a rate of increase of a temperature of the battery system during the applying;
• during the heating time duration, performing 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
• adjusting the AC heating current during the applying based on the temperature and the impedance measurement.

A vehicle system comprising:

• a memory having computer readable instructions;
• and
• a processing device for executing the computer readable instructions, the computer readable instructions controlling the processing device to perform a method including:
• controlling a heating control module to generate an alternating current (AC) heating current;
• heating a battery system to a desired temperature by applying the AC heating current to the battery system over a selected heating time duration;
• monitoring a rate of increase of a temperature of the battery system during the applying;
• during the heating time duration, performing 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
• adjusting the AC heating current during the applying based on the temperature and the impedance measurement.