1. A method of controlling operation of a hybrid vehicle having an engine and a secondary power source, the method comprising: determining an engine torque command based on a request for vehicle acceleration or deceleration, a target power level of the secondary power source, and a current engine power command; determining an engine speed command based on the target power level of the secondary power source, a total engine power command, and vehicle speed; and operating the engine based on the engine torque and engine speed commands.