Systems and methods for particulate filter load estimation

A hybrid vehicle system, comprising:

• an engine including one or more engine cylinders;
• an electric machine coupled to a battery;
• one or more fuel injectors coupled to the one or more engine cylinders;
• an engine intake manifold;
• an engine exhaust manifold including an exhaust passage;
• a particulate filter (PF) coupled to the exhaust passage, an exhaust pressure sensor coupled to the exhaust passage, and an exhaust temperature sensor coupled to the exhaust passage;
• and
• a controller with computer readable instructions stored on non-transitory memory for:
• estimating a PF temperature immediately prior to an engine shutdown via the exhaust temperature sensor;
• estimating an amount of soot accumulated on the PF immediately prior to the engine shutdown via the exhaust pressure sensor;
• in response to the estimated PF temperature being higher than a threshold temperature, estimating an amount of soot burned during an engine non-combusting condition based on a change in PF temperature;
• and
• regenerating the PF during an immediately subsequent engine combusting condition based on the amount of soot accumulated on the PF during engine operation which is offset by the amount of soot burned during the non-combusting condition.