Variable Switching Frequency Techniques for Power Converters: Review and Future Trends

Variable-frequency (VF) techniques have been widely applied in the fields of power electronics and motor drives. Based on the categories of frequency variables, the VF techniques can be typically classified into three perspectives: variable drive speed frequency, variable switching frequency (VSF), and variable sampling frequency. The speed frequency is related to the motor speed/torque control and has already been well summarized. VSF techniques for power converters can also be leveraged in isolated/nonisolated topologies to improve the performances in the aspects of switching loss reduction, power transfer optimization, optimal voltage/current control, and electromagnetic interference noise reduction. The corresponding works on VSF techniques lack systematic study and review. This article studies the VSF techniques based on the methodologies and application purposes. The detailed classification and analysis for VSF techniques are derived according to the existing publications. The typical analyzed techniques have been compared and validated experimentally in this article to show the effectiveness. Also, the inspirations and future trends are studied and summarized.