This paper proposes a resonant current reduction method by the Triangular Current Mode (TCM) for an active clamp AC-DC flyback converter. An active-clamp flyback converter has been widely considered because of Zero Voltage Switching (ZVS) by the active-clamp circuit. However, the resonant current increases the conduction loss of the flyback converter. The proposed method reduces the resonant current by adjusting the switching pattern of the active clamp circuit. Moreover, TCM is applied to achieve ZVS for the switching loss minimization. Experimental results show that the fly-back converter achieved ZVS by TCM control. Finally, the conduction loss of the active-clamp AC-DC flyback converter was reduced by 5.6%.

We developed a leg extender exoskeleton that extends the leg length by approximately 40cm. We investigated link length configurations to minimize physical fatigue, which is expected to contribute to safer exoskeleton operation.

In this paper, we selected a kite shape configuration that minimizes lower-limb joint torque based on simulation results, and a parallelogram shape configuration that provides high foot-positioning accuracy according to the linearity index. Furthermore, to evaluate the effects of these two configurations on stepping, experiments were conducted using an actual device. The results suggest that the kite shape configuration may contribute to reduced physical fatigue.

Our laboratory conducts research on power conversion circuits and their control. Our research covers converter and system control as well as the behavior of power semiconductor devices during individual switching events. We also develop automated measurement environments to support efficient and safe experiments under various conditions.