Switching Type Power Amplifier Using Multilevel Inverter

Abstract

This paper presents a 10kW, 200kHz power amplifier using the technology of multilevel inverters. Recently, the amplifier is required to have both high power and high efficiency to replace the class A transistor amplifiers. Its amplifier is composed of two pairs of 5-level inverters with interphase reactors. Different 81 switching patterns are used to output 9-level voltage. So that it is able to give better allowance of control degree. The proposed multilevel inverter has two switching control patterns. At one switching pattern, the sequential control of the switching devices can decrease the switching frequency. At the other switching pattern, the circulating current can be limited without changing the output voltage level. The former switching pattern is activated when the circulating current within the threshold value and the latter switching pattern is activated when the circulating current is out of threshold value. By employing these two control methods, the switching frequency can be reduced by about 1/8 times and the circulating current can be limited by ±1A for 10kW system. This paper also presents the effectiveness of characteristics, THD of output waveforms and the experimental results of output waveforms.