Abstract
Accounting for the development of automation, PWM (pulse width modulation)-modeamplifiers have been used in many servo mechanisms. The merits of PWM-mode amplifiers are low cost because of the recent development of high power transistors and low loss of energy. But it is difficult to find the quantitative characteristics of the PWM-mode amplifier in the closed loop that includes the PWM-mode amplifier, because the PWM-mode amplifier has the nonlinear dynamic characteristics. In this study we find the equivalent linearized transfer function of the PWM-mode amplifiers according to analyzing the relation between the input and the output signals of the PWM-mode amplifiers in the frequency domain. As the results of this study, it is found that the dynamic characteristics of the equivalent linearized transfer function are well agreed with the dynamic characteristics of the PWM-mode amplifier on the step responses and the frequency characteristics of the PWM-mode amplifier by the analog simulation of the PWM-mode amplifier. And it is also shown that the carrier frequency of the PWM-mode amplifiers shows the dither effect for the solid friction.
