An Observer-Based Automated Averaging Technique for Power Electronic Circuits

Average-value models are commonly used in the design and analysis of power electronic-based systems as a method of portraying the overall system dynamics while neglecting discontinuities that arise from switching. Although numerous averaging methodologies have been developed to eliminate discontinuities, they are typically limited to specific circuits operating in specific modes. Therefore, substantial analytical effort is generally required to select an appropriate averaging technique and develop the corresponding average-value model that is valid for a given converter. To reduce this effort, an automated averaging technique is set forth in which an averaged model is established via coupling with a detailed simulation of the system. The structure of the averaged model is based upon state-space averaging with the detailed simulation used to calculate state models for each switching topology, the time spent per cycle in each topology, and the operating mode (continuous or discontinuous) of the circuit. However, since classical state-space averaging is not applicable to circuits with state-dependent switching logic and does not portray high-frequency dynamics associated with discontinuous states, a state feedback loop is introduced such that the high-frequency dynamics associated with state-dependent switching or discontinuous modes are accurately portrayed. To demonstrate the new technique, two example systems are examined, a PWM-controlled buck converter operating in both continuous and discontinuous modes and a buck converter with a hysteresis current controller. The new averaging technique is verified by comparison with established analytical and numerical methods.