Seven-level single-leg flying capacitor converter voltage balancing dynamics analysis

Time domain approach based on stitching analytical solutions for consecutive switching subintervals is applied to analysis of seven-level single-leg flying capacitor converter natural voltage balancing dynamics for Phase Shifted PWM. Expressions for voltage balancing dynamics frequencies and time constants reveal dependences on load parameters, carrier frequency, and voltage command. The root cause of poor (zero) natural voltage balancing damping phenomenon in odd-level single converters with Phase Shifted PWM is explained by analyzing specific switching topologies. The remedy may be modulation strategies that use different from classic Phase Shifted PWM switching states and provide faster natural balancing dynamics without compromising optimal voltage quality of nearest level switching, minimal integral switching loss and uniform switching loss sharing between converter switches. In particular, the amount of employed zero voltage switching states must be increased.