The electro surgical generator (ESG) is a high-frequency-voltage inverter that utilizes the current thermal effect to achieve the surgical therapeutic effect. Determined by the circuit topologies, sinusoidal and square waves are commonly utilized as the output voltage waveforms, which show certain disadvantages on wide-range voltage regulation. This paper studies the ESG with the trapezoidal voltage waveform, which has more control freedom degrees for voltage regulation, including the voltage amplitude as well as the rising and falling edge time. Therefore, it can reach a good balance between the total harmonic distortion (THD) and the voltage amplitude. This paper studies a multi-phase interleaved reconfigurable high-frequency-voltage inverter with the trapezoidal voltage waveform. To optimize the converter parameters and operation modes within the entire load range, a multi-obj ective optimization design method is proposed, which can optimize THD, current ripple and efficiency comprehensively. A 200V input and 200W output prototype was built in the laboratory, and the experimental results verify the feasibility of the proposed design method.

The electrosurgical generator (ESG) is a medical power supply device that utilizes the thermal effect of high-frequency current flowing through the body tissues. It needs to maintain constant output power when the tissue load varies over a wide range during treatment, which means that wide-output high-frequency voltage should be provided by ESGs. Moreover, the frequency of the output voltage had better be stable to ensure a good therapeutic effect. However, most ESGs control the power by adjusting the frequency or the shape of the output voltage. This paper proposes a two-stage structure with a resonant DC/DC converter as the first stage and a class DE resonant inverter as the second stage. Due to the resonant structure, not only do all the semiconductors achieve ZVS operation, but also the converter is suitable for wide-range voltage regulation. The simulation results and the experimental waveforms verify the theoretical analysis and effectiveness.

Flyback converter is widely used for low-power DC/DC conversion with the simple circuit structure. However, it suffers high switching loss caused by its hard switching operation when the switching frequency is enhanced. This paper proposes a high-frequency resonant DC/DC converter based on the traditional flyback converter. The converter employs a resonant inductor and two resonant capacitors, which achieves soft switching of the switch and the diode. It can also absorb the parasitic parameters of the circuit. Therefore, the converter can enhance the switching frequency to improve the power density without increasing the loss obviously. Furthermore, the circuit performance gets further improved by reversing the connection of the dotted terminals of the transformer. The operation principles are presented in detail. And the ON-OFF hysteresis control is applied to adjust the output voltage. Finally, a 10MHz prototype with 12V input and 5V/10W output was built to verify the theoretical analysis.

This paper proposes a nine-bridge single-stage isolated three-phase bidirectional AC/DC converter, which realizes buck-boost voltage regulation, high-frequency electrical isolation, and bidirectional power transmission. The converter adopts three transformers to distribute the total power equally, and the number of switches is significantly reduced by optimizing the topology. The Y-Δ connection of the transformer can provide an additional step-down conversion ratio. The improved Space Vector Pulse Width Modulation (SVPWM) algorithm is proposed to guarantee the voltage-second balance of the transformers and unity power factor control of the AC side. The proper selection of the switching states of the zero voltage vector contributes to an increase in the operating frequency of the transformers, which is 1.5 times that of the switches connected with them. The operating principles of the converter are presented in detail as well as its SVPWM algorithm. The simulation results under the rectifier mode and the inverter mode in MATLAB/Simulink validate the theoretical analysis well.