Search

This article exhibits an output voltage-derivative observer-based output voltage-tracking technique for dc/dc boost converters without current feedback, taking the model-plant mismatches (caused by parameter and load variations) and model nonlinearity into consideration. In contrast to extant passivity-based approaches, the proposed solution includes observers to estimate the output voltage derivative and does not require exact model information, which offers a few features: converter parameter information-free output voltage-derivative observers including the modified disturbance observation algorithm for improving the high-frequency disturbance rejection capability as a replacement of the estimation error integral actions, and the observer-based output voltage and its derivative error stabilizer with a damping adaptation mechanism assigning the desired energy function to the closed-loop system. Experimental verification is provided to demonstrate the practical advantages of the proposed solution using a 3-kW bidirectional converter. [ABSTRACT FROM AUTHOR]

Three-level neutral-point-clamped (3L-NPC) voltage source inverters are widely used in many low- and medium-power applications. However, the 3L-NPC inverter has an inheritance issue of the neutral-point (NP) voltage unbalancing due to the deviation of dc-link capacitor voltages causing distortions for the output waveform quality. Generally, discontinuous pulsewidth modulation (DPWM) is used to diminish the stress on power transistors and prolong their lifespan, however; it is not capable of solving the issue of NP voltage unbalancing. Therefore, this article proposes a simple voltage balancing control based on DPWM with a hysteresis NP voltage band. The balancing control method is only activated once the capacitance voltage error exceeds the hysteresis band by generating a momentary offset on the opposite direction of the DPWM offset. In this way, both top and bottom capacitance voltages will converge within a predefined error band. Various hysteresis error bands are investigated by analyzing the power losses, total harmonic distortions, and common mode voltage. The advantages of this proposed method are its simplicity and ease of control while maintaining the features of DPWM. The effectiveness of the proposed method is validated using simulation and experimental results. [ABSTRACT FROM AUTHOR]