A High-Efficiency Bipolar Pulse Generator Based on a Push–Pull Inverter for Tissue Welding

The push–pull inverter topology inherently incorporates a transformer, making it suitable for electrosurgical generators without requiring an additional transformer. However, conventional push–pull topologies exhibit limitations, including high switch stress and the absence of a dedicated path for releasing transformer leakage-inductance energy, which may increase switching losses at high frequencies. This paper presents a bipolar pulse generator based on a push–pull inverter topology, offering a new engineering approach for electrosurgical applications. The prototype achieves soft-switching operation over a load range of 30–1000 Ω, reducing design complexity, extending load adaptability, and improving system reliability while meeting the stringent pulse-width control requirements of bipolar electrosurgical applications. In addition, based on an equivalent-impedance model of tissue welding, the operating modes and soft-switching mechanisms of the push–pull inverter under different dynamic load conditions are analyzed, and strict constraints relating to dead time, load resistance, and circuit parameters are derived. A bipolar pulse-generator prototype operating at 400 kHz was developed to validate the theoretical analysis. Experimental results show a conversion efficiency of 86–94% over a dynamic load range of 25–250 Ω. At a moderate nominal load, the system maintains an efficiency above 93% over an output-power range of 4.92–183.69 W, achieving high-efficiency operation across a power range relevant to electrosurgical applications. While maintaining tissue-welding quality, the proposed system improves overall efficiency, demonstrating the feasibility and engineering value of the topology and control strategy for bipolar electrosurgical generators.