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频率特性是描述控制系统性能的主要指标之一 ,在采样控制系统中 ,离散信号与连续信号并存 ,由于采样开关的存在 ,使得采样控制系统具有周期时变性 ,因而无法直接用传递函数来描述系统的频率特性 .基于采样控制系统直接设计理论 ,给出了采样控制系统幅频特性的计算方法 .首先应用提升技术 ,将周期时变系统转化为线性时不变系统 ,从而解决了采样控制系统周期时变、连续信号和离散信号共存的问题 ,并通过求解提升系统的幅频等效离散系统来求得采样控制系统的幅频特性 .最后用具体的计算实例验证了该方法的有效性 ,并对方法的准确性进行了分析
The frequency characteristic is one of the main indicators to describe the performance of the control system. In the sampling control system, the discrete signal and the continuous signal coexist. Due to the existence of the sampling switch, the sampling control system has the characteristics of periodic variation. Therefore, the transfer function can not be used directly to describe the system Based on the direct design theory of sampling control system, a method of calculating the amplitude-frequency characteristics of sampling control system is given.Firstly, using lifting technology, the periodic time-varying system is transformed into a linear time-invariant system to solve the problem of sampling control system period Time varying, coexistence of continuous signals and discrete signals, and obtain the amplitude-frequency characteristics of the sampling control system by solving the amplitude-frequency equivalent discrete system of the system.At last, the validity of this method is verified by a concrete example The accuracy of the method was analyzed