采用双环控制的多电平D类功率放大器

介绍了一种新颖的基于级联型多电平拓扑结构的开关式功率放大器,采用相移PWM技术,其开关频率是单个单元开关频率的2N倍,通过电压电流双闭环控制保证输出信号的跟随品质,本文着重研究了双闭环控制的设计方法.试验结果表明,采用电流电压双闭环控制的D类功率放大器,系统带宽较宽,具有较好的瞬时响应和输出品质.

Design of a Cascade Multilevel Class-D Amplifier Based on Dual Feedback Loop Control

A novel switch-mode power amplifier based on a cascade multicell multilevel circuit topology is introduced in the paper. By application of the concept of multicell topologies being operated in a phase-shifted PWM control to switch-mode amplifier systems, the effective switching frequeney of output results is in 2N times of the switching frequency of each full-bridge. Based on the single-phase inverter topology, or H-bridge, the amplifier is more easily accomplished by the direct series, or parallel connection of multiple H-bridge power-stages. The principle of the phase-shifted PWM control is described, operating these with which gives higher output power and produces an improved output voltage spectrum and significantly lowers output current-ripple. Furthermore, comparing the conventional switch-mode amplifiers, a significantly improved EMI behavior can be expected because only voltage transitions of amplitude. The design method of velocity and current dual feedback loops control of class-D amplifier is developed, which improves the output voltage quality. The results of measurements taken from a laboratory setup are presented.