Modified Voltage Controller to Reduce Harmonics in Three-Level Boost PFC Converters

The three-level boost (TLB) PFC converter offers advantages such as lower voltage stress on switches and diodes, reduced size and volume of passive components, and minimized EMI and core losses. Multiloop control is widely used for TLB PFC converters because of its simplicity, computational efficiency, and ease of implementation. However, multiloop control strategy introduces a second-order harmonic in voltage controller output, leading to third-order harmonic distortion in input current and degrading THD performance. Existing solutions either add complexity by using filters or provide only partial attenuation without complete elimination of second-order harmonic. To address this, a modified voltage controller incorporating a zero-order hold $(\mathbf{Z O H})$ and a switching mechanism is proposed. The $\mathbf{Z O H}$ removes the second-order harmonic from the voltage controller output, while the switch ensures fast transient response. The proposed control method is validated through simulation and experimental results.