Constraints Based Design of DC side LC Filter for Single-Phase Voltage Source Converter

Single-phase Voltage Source Converters (VSC) are required to handle significant second harmonic ripple current caused by the mismatch between instantaneous input and output power. Different passive and active filters are employed for protecting sensitive loads and sources, e.g., battery, photovoltaic (PV) cell, etc. from large ripple current. Tuned LC filter is one of the well-accepted filtering solutions for single-phase VSCs as it significantly reduces the capacitance requirement compared to a capacitive filter. The better filter performance and enhanced reliability without addition of any active component make it suitable for low-cost applications. However, the choice of inductance ( L) and capacitance ( C) in LC tuned filter is not unique and often decided by the desired Q factor, which, in turn, shapes the filter characteristics in the passband region. This paper proposes a cost minimized selection procedure of L and C for the tuned filter in single-phase VSC. The cost study has been carried out considering the film capacitor and laminated steel inductor. The objective function for optimization is generalized to include volume and impedance characteristics of the filter. The cost optimized design of the LC filter is compared with the capacitive filter with respect to steady-state and transient performances.