电压—频率转换电路的动态特性分析及求解  

Analysis on Dynamic Characteristics of Voltage-Frequency Converter Circuit

作　　者：叶林[1] 李昌禧[1] 张杰[1] 张洪[1] 向廷元[1] 

机构地区：[1]华中科技大学控制科学与工程系,武汉430074

出　　处：《仪表技术与传感器》2002年第6期41-42,48,共3页Instrument Technique and Sensor

摘　　要：在测量与仪表技术领域 ,V/F转换器作为一种信号变换和处理技术 ,应用日益广泛。从V/F转换器内部工作原理出发 ,分析了V/F转换电路的动态特性 ,提出了能说明V/F转换过程快慢程度的一个动态参数概念 ,即转换时间 ,并求解出普遍有效的一般表达式。V/F转换器的动态转换过程主要由两步组成 ,一是恒定脉宽的单脉冲输出 ,二是单稳态复位状态 ,这两种状态交替工作控制输入积分比较器的积分工作状态 ,得到频率大小与输入直流电压成比例的脉冲输出信号从而实现V/F。转换当设在任意时刻输入电压发生突变时 ,可用阶跃函数来描述此变化 ,定义转换时间Tc为跳变时刻至达到稳定脉冲输出的时间 ,则此时间成为描述V/F动态转换过程的一个具体的动态参数。求解出的Tc具有普遍有效性 ,并从中能清楚地看出V/F的动态响应特性不仅与输入电压新的数值有关 ,而且还与输入原初始状态、跳变时刻有关 。V/F converters are increasingly applied in measurement and instrumentation field as a method of signal conversion and processing.However,the dynamic transient characteristics of V/F converters is rarely concerned.Based on discussion of working principle of typical V/F converter circuit,analyzes the dynamic transient characteristics of the V/F converters,obtains a formula of general validity for describing transient conversion process.The dynamic transient conversion proceeds basically in two phases,one is constant-width narrow pulse output of a single-stable-state filp-flop,the other one is reset state.The flip-flop alternates in these two phases and controls an input comparison integrator working in the two corresponding states,so that a frequency signal is produced.The frequency of the output signal is proportional to the value of the direct-current input signal V I. Suppose input V I have a transient change to a new value,which can be considered as a step input,define conversion time Tc the time needed for the complete conversion from the reference time point of initial state to the time the pulse output of new frequency starts.The Tc can be regarded as a describing parameter for the V/F transient conversion process.The formula of Tc is of general validity and explicates that the transient conversion time Tc has relation not only with the value of the input V,but also initial state value,change time,which shows that the transient conversion characteristics of V/F converter isdifferent from that of analog input-output systems.

关 键 词：转换时间 电压一频率转换电路 动态特性 

分 类 号：TM93[电气工程—电力电子与电力传动]