In this paper, we develop a variable-frequency pulse width modulation (VFPWM) circuit for input control of 6.78-MHz resonant wireless power transfer (WPT) systems. The zero-voltage switching relies on the adjustments both duty cycle and frequency class-E amplifier used in WPT as transmission unit. High-frequency wave integrated circuits exist, but some have insufficiently high or unfavorable re...

In this research, optimization of the pulsed gas tungsten arc welding including pulse current, background current, pulse frequency and on time were investigated in welding of non-similar materials of austenitic stainless steel AISI 316L and nickel-base super alloy of Monel 400 by using ERNiCr3 filler metal. In order to obtain optimum conditions of welding the Taguchi method with the L9 array wa...

This paper considers the theoretical and experimental approaches to performance improvement of pneumatic linear actuators. Two On/Off, 3/2 pneumatic valves were used to control the position of a pneumatic piston rod through the closed-loop application of a PWM (Pulse Width Modulation)-sliding mode algorithm. System parameters have been experimentally selected in order to reduce the tracking err...

An analysis is made of the deflected forms assumed by an elastic strip when it is bent and stretched around a rigid drum. A summary is first given of the method of analysis used and the results obtained in a previous study where the drum width is equal to or greater than that of the strip. This work is then extended to the case where the strip width exceeds that of the drum. Defiected forms and...

Because of the serious non-linearity and coupling among state variables caused by the complex energy conversion process in ultrasonic motor, the motion control strategy of ultrasonic motor still need to be studied in detail to obtain better performance. As a kind of special control method, the low-frequency PWM control strategy can make the on-line optimum control easier, and may be an effectiv...

This paper presents a novel control method to improve the efficiency of low-voltage DC-DC converters at light loads. Pulse Width Modulation (PWM) converters have poor efficiencies at light loads, while pulse frequency modulation (PFM) control is more efficient for the same cases. Switching losses constitute a major portion of the total power loss at light loads. To decrease the switching losses...

In this thesis, I present a novel, replicated multi-wavelength electro-optic measurement system. In the proposed system, multiple laser sources at different wavelengths go through an electro-optic modulator at the same time to measure a single electrical pulse. The primary aim is to increase the number of temporal measurement points beyond what can be achieved by conventional methods. Since the...