Numerical control rheostat device

Abstract

The present invention provides a digitally controlled rheostat device, comprising a first port A, a second port B, and a voltage regulation circuit connected between the first port A and the second port B. The voltage regulation circuit includes: a standard resistor R, a compensation voltage source US and a digitally controlled voltage source U with a variable output voltage. The compensation voltage source US uses an anti-phase follower circuit 2 to offset the voltage drop at both ends of the standard resistance R; wherein, one end C of the standard resistance R is connected to the first port A, and the other end D is connected to the first port A. The output terminal US- of the compensation voltage source is connected; the reference ground terminal US+ of the compensation voltage source US is connected to the reference ground terminal U+ of the digital control voltage source U; the output terminal U- of the digital control voltage source is connected to the The second port B is connected; the output terminal US_ of the compensation voltage source US is connected to the reference input terminal of the digital-to-analog conversion circuit 3 in the digital-control voltage source to provide a reference terminal voltage for the digital-control voltage source. The above device has the advantages of stable analog output resistance, adjustable resolution and wide range of analog resistance.

Description

technical field [0001] The invention relates to the technical field of industrial control, in particular to a numerically controlled rheostat device. Background technique [0002] With the development of electronic technology, in the field of industrial process control calibration, more and more instruments use numerical control rheostat design to facilitate the application. However, there is a common problem in the current rheostat devices on the instrument: the existing rheostat devices generally need to add a current (voltage) source in the circuit to simulate the resistance characteristics. When simulating near zero resistance, the numerical control current (voltage) ) source output is close to its upper limit value, affected by the stability characteristics of its internal electronic devices, the absolute value of the output signal fluctuation is larger than when it outputs a small signal, resulting in poor stability when simulating a small resistance value. In additio...

AI Technical Summary

Problems solved by technology

However, there is a common problem in the rheostat devices on the instruments at present: the existing rheostat devices generally need to add a current (voltage) source in the circuit to simulate the resistance characteristics. When simulating near zero resistance, the numerical control current (voltage) ) The source output is close to its upper limit value, affected by the stability characteristics of its internal electronic devices, the absolute value of the output signal fluctuation is larger than when it outputs a small signal, resulting in poor stability when simulating a small resistance value

In addition, when the output of the digital-to-analog conversion circuit of the existing rheostat is zero, the analog resistance output is not zero resistance, resulting in fixed resolution, and it is impossible to simulate higher resolution in the range of small resistance values.

In addition, the existing varistor has weak anti-interference ability of high-frequency current noise on the external excitation current, and when it cooperates with the field equipment powered by switching power supply, the reading jumps greatly

The existing rheostat simulation range is limited, and the resistance value simulation from 0 to infinity cannot be realized

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