对称PWM减小H半桥型开关功放电流纹波的新方法

摘要

As the two-level H-half bridge switching power amplifier has significant current tipple,resulting in heavier load loss,a three-level H-half bridge switching power amplifier with two symmetrical PWM signals is proposed,one of which has fixed duty ratio and the other verified. The analytical computation of current ripple is presented and the numerical simulation is carried out with Matlab. An experimental switching power amplifier controlled by DSP is constructed and the comparative test is performed between two-level and three-level H-half bridge switching power amplifiers. All show that the amplifier with two symmetrical PWM signals has much lower output current ripple.%针对H半桥两电平开关功率放大器输出电流纹波较大导致负载损耗增加的缺点,提出采用2路中心对称但占空比不同的PWM实现三电平工作方式的新方法,称为对称PWM法.该方法采用一路PWM占空比固定,另一路PWM占空比受控可变的原理实现了三电平工作方式.给出了输出电流纹波计算公式,利用Matlab对开关功率放大器进行了仿真,构建了以DSP为控制核心的数字式开关功率放大器试验平台,进行了两电平和三电平开关功率放大器对比试验.理论分析、数字仿真和试验结果的一致性表明,采用对称PWM法能够有效地减小H半桥开关功率放大器输出电流纹波.