Design of a Compensation Network for an LLC Power Converter Applied to Motor Drive Control Systems under Rapid Load Variations

Pham Van Hiep, Nguyen The Truyen, Pham Vu Khiem, Dinh Van Linh, Hoang Thi Phuong Thao, Pham Duy Dat

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Published Jul 31, 2026
DOI: https://doi.org/10.25073/2588-1124/vnumap.5124

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VAN HIEP, Pham et al. Design of a Compensation Network for an LLC Power Converter Applied to Motor Drive Control Systems under Rapid Load Variations. VNU Journal of Science: Mathematics - Physics, [S.l.], july 2026. ISSN 2588-1124. Available at: <https://js.vnu.edu.vn/MaP/article/view/5124>. Date accessed: 12 aug. 2026. doi: https://doi.org/10.25073/2588-1124/vnumap.5124.
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Abstract

The paper focuses on the design of a Type II compensation network for a 500 W half-bridge LLC converter to stabilize a 60 VDC output voltage supplied to a motor under rapidly changing load conditions. By applying the K-factor method in combination with SIMPLIS-based simulation, the design parameters of the compensation network are selected and verified, enabling the system to achieve a crossover frequency in the range of 3.89 kHz - 4.6 kHz and a phase margin of 28.3°–37° across an input voltage range of 370-410 VDC. Experimental results show that when the load current changes abruptly from 0 A to 9 A, the output voltage undershoot is limited to 938 mV, while the overshoot during load removal is 705.5 mV. With the transient voltage deviation maintained below approximately 2% and the output voltage returning to steady state without sustained oscillation, the proposed compensation network improves the load-transient response and helps preserve the regulated DC output-voltage quality within the investigated operating range. These results support the feasibility of the compensated LLC converter for regulated drive-supply applications and provide a basis for further power-density improvement in future work.

Keywords: LLC resonant converter; Type II compensator; K-factor design; load transient response; BLDC motor drive; closed-loop control.

References

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