Yajie Qiu

Title: Yajie Qiu: Innovator in Power Supply Technology

Introduction

Yajie Qiu is a notable inventor based in Kanata, Canada, recognized for his contributions to power supply technology. With a total of five patents to his name, he has made significant advancements in the field of AC/DC switching mode power supplies.

Latest Patents

One of his latest patents is focused on a PFC optimization architecture for AC input AC/DC switching mode power supplies. This invention includes a boost follower circuit (BFC), a hybrid bulk capacitance circuit (HBCC), and driver and control circuitry. The BFC is designed to sense the peak AC input voltage and adjust the PFC output voltage Vdc based on the AC input voltage, thereby improving low line efficiency and reducing losses. The BFC can operate in either a stepless or step regulation mode to follow the AC input line voltage. The driver and control circuitry coordinates the operation of the BFC and HBCC, utilizing comparator circuitry to selectively connect bulk capacitors of varying voltage ratings. This innovation results in a reduction in capacitor height and volume, enhancing the power density of isolated AC/DC power supplies.

Another significant patent by Yajie Qiu involves an architecture for AC/DC SMPS with PFC and a multimode LLC DC/DC converter. This invention comprises a PFC stage, an isolated LLC DC/DC converter stage, and a control circuit that provides feedback and control signals to the PFC and LLC controllers. The system enables multiple operating modes based on the sensed peak AC input voltage and required output voltage Vo. The PFC generates a first DC bus voltage Vdc for low line AC input and a second DC bus voltage for high line or universal AC input. The multi-mode LLC converter can operate in either half-bridge or full-bridge mode, depending on the input conditions.

Career Highlights

Yajie Qiu has worked with prominent companies in the industry, including Gan Systems Inc. and Infineon Technologies Canada Inc. His experience in these organizations has contributed to his expertise in power supply technologies.

Collaborations

Throughout his career, Yajie has collaborated with talented individuals such as Xuechao Liu and Larry Spaziani. These collaborations have further enriched his work and innovations in the field.

Conclusion

Yajie Qiu is a distinguished inventor whose work in power supply technology has