基于逆全极点滤波器的高频PWM噪声整形方法  

Noise Shaping Method for High Frequency PWM Based on Inverse All Pole Filter

作　　者：陈福祥 刘凯 胡傲奇 张昊 赵烁 曾理湛[1] Chen Fuxiang;Liu Kai;Hu Aoqi;Zhang Hao;Zhao Shuo;Zeng Lizhan(School of Mechanical Science&Engineering Huazhong University of Science and Technology,Wuhan 430074 China)

机构地区：[1]华中科技大学机械科学与工程学院,武汉430074

出　　处：《电工技术学报》2024年第10期3129-3140,共12页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金资助项目(52275112,52075193)。

摘　　要：高频开关功率放大器具有高功率、低纹波、高响应的优点,是高加速、高精度定位系统的核心部件。为了解决高频PWM中开关频率与占空比分辨率的矛盾,该文分析调制中噪声整形的基本原理,采用误差反馈结构提取PWM量化噪声进行数字整形,阐述噪声整形滤波器设计约束条件。提出通过逆全极点无限脉冲响应(IIR)滤波器获得有限脉冲响应(FIR)噪声整形滤波器的简明设计方法,仿真及实验表明,该文提出的方法可利用低阶FIR整形滤波器获得平坦的通带和高整形衰减。在不足9位的PWM中,4阶的FIR噪声整形滤波器能够恢复调制信号在10 kHz频段内约40 dB的信噪比损失。To keep track of the requirements of driving the high-precision electromechanical system in semiconductor manufacturing,the SNR of the amplifier output current needs to increase by 20 dB every five years.Compared to linear power amplifiers,switching power amplifiers have superior potential in power and efficiency.High-frequency switching power amplifiers can reduce voltage and current distortion.However,the limited digital computation causes a conflict between high switch frequency and high-duty cycle resolution.Therefore,this paper analyzes the noise shaping principles in the pulse-width modulation process and proposes a simple design method for low-order FIR noise shaping filters,which provides sufficient noise attenuation and passband flatness with the least computational cost.Firstly,the signal processing in switch power amplifiers is demonstrated.Quantization noise in digital PWM modulation causes a trade-off between high SNR and high frequency,assumed to be uniformly distributed white noise and independent of the input.The improvement of the SNR via noise shaping is analyzed accordingly.Secondly,an error feedback structure is used to obtain the quantization noise as high-bit digital signals,separating the transmission of target signals and quantization noise shaping processing.Furthermore,the minimum phase and stability constraints of noise-shaping filters are derived.Thirdly,four different types of all-pole IIR filters are derived by the Gegenbauer polynomial.Their inverse forms are FIR filters with the origin cutoff frequency and shaping attenuation as well as the minimum phase and coefficient characteristics.Finally,the noise attenuation requirements are met by selecting the filter order reasonably.The inverse all-pole filter method reduces the complexity of the noise-shaping filter design and enhances the ability to control the ripple in the noise-shaping band.Simulation and experiment have shown that the proposed method achieves a large noise attenuation in the same order as the LMI method and has bett

关 键 词：开关功率放大器 高频 PWM 噪声整形 全极点滤波器 信噪比 

分 类 号：TM46[电气工程—电器]