Compression ratio methods and systems for particulate filter regeneration

Methods and systems for enabling regeneration of a particulate filter of an engine system are provided. In one embodiment, a method includes: receiving, by a processor, a request for particulate filter regeneration; in response to the request, determining, by the processor, at least one of a compression ratio and an expansion ratio; generating, by the processor, control signals to actuators of the engine system to adjust the at least one of the compression ratio and the expansion ratio to achieve a desired exhaust temperature; generating, by the processor, control signals to actuators of the engine system to optimize torque output based on the desired exhaust temperature, engine speed, and a desired engine load; and initiating, by the processor, regeneration of the particulate filter based on the command signals.