电磁轴承功放由偏置漂移引起调制失效的问题研究  

Research on Modulation Failure Due to Bias Voltage Drift of PWM in Switching Amplifier of Active Magnetic Bearing System

作　　者：周元[1] 蒋科坚[1] 

机构地区：[1]浙江理工大学信息学院,杭州310018

出　　处：《浙江理工大学学报（自然科学版）》2017年第5期662-668,共7页Journal of Zhejiang Sci-Tech University(Natural Sciences)

基　　金：国家自然科学基金项目(11272288);浙江省公益技术应用研究项目(2015C31063);浙江理工大学研究生创新项目(XX-CX16006)

摘　　要：分析了三角波比较法三电平PWM开关功放由于偏置电压的漂移引起的调制失效机理。为避免调制失效,在三电平PWM开关功率放大器的基础上,提出一种结合三角波比较法和采样保持法的混合调制方法。该方法中功率主电路的两个桥臂由三角波比较电路和采样保持电路分别控制,根据三角波载波幅值和静态电流误差均值分别确定偏置电压值,满足了在理论偏置电压值漂移情况下的脉宽调制要求。分析了混合调制开关功放避免失效的工作原理并实现电路。仿真和实验均表明:该方法设计的功率放大器不仅可以解决由于偏置电压漂移带来的PWM调制失效,并且具有电流纹波小、响应速度快、受负载参数影响小等优点。Modulation failure mechanism caused by bias voltage drift in three-level PWM of the switching power amplifier in AMB system was analyzed in this paper.Based on the three-level PWM switching power amplifier,a novel hybrid modulation method was proposed,which consists of the triangular wave modulation and the sample-and-hold（S/H）circuit with a D flip-flop.The two bridge arms of the main circuit were respectively controlled by the triangular wave comparison circuit and the S/H circuit,and the bias voltage value was respectively determined by the triangular wave amplitude value and the mean value of the static current error.This meets the pulse modulation requirements under the situation of theoretical bias voltage drift.The principle of the proposed hybrid modulation was illuminated in detail and its circuit implementation was given.The simulation and experimental results show that the proposed modulation method can not only get rid of the failure due to the bias voltage drift in PWM,but also has the advantages of low current ripple,fast response speed and little influence of load parameters.

关 键 词：电磁轴承 开关功率放大器 三电平PWM 混合调制 

分 类 号：TH133[机械工程—机械制造及自动化]