Self-detection circuit for implementing digital input circuit based on pulse injection method

Abstract

The invention provides a self-detection circuit for implementing a digital input circuit based on a pulse injection method. A peak self-detection pulse is controlled and generated through an IO pin of a CPU and is injected into the digital input circuit through a high voltage capacitor. After optical coupling, the peak self-detection pulse is collected by an ADC pin of the CPU and judged. A pulse injection circuit is mainly formed by a high speed optical coupler, an optical MOS tube, a resistor, and a high voltage safety capacitor. The IO pin of the CPU is connected to an input end of the high speed optical coupler. An output end of the high speed optical coupler is connected to the input end of the optical MOS tube. A source electrode of the optical MOS tube is connected to a common anode of a power supply. A drain electrode of the optical MOS tube is connected to one end of the high voltage safety capacitor. The other end of the high voltage safety capacitor is connected to the digital input circuit. After the IO pin of the CPU drives and generates a peak self-detection pulse signal and injects the signal into the digital input circuit, the ADC pin of the CPU collects optical coupler secondary waveform, and carries out processing, analysis and comparison. Thus the self-detection judgment of the digital input circuit integrity is achieved. The self-detection mode can be applied when a digital input signal is in any state, and the self-detection circuit has the super-high isolation capacity and reliability.

Description

Technical field [0001] The invention relates to the technical field of power system self-inspection protection control, in particular to a method for realizing a self-inspection circuit of a digital input loop based on a pulse injection method and a device using the method. Background technique [0002] In power system substation automation and industrial control automation devices, a switch input (hereinafter also referred to as switch input) acquisition loop is usually set to obtain the status of some important digital signal quantities, and provide the necessary basis for subsequent protection and control operations. For the realization of the digital input circuit, the electric energy of the input signal is usually used to drive the primary side of the input circuit optocoupler, and the state change of the input signal is converted into a voltage signal through a pull-up resistor on the secondary side of the optocoupler. The relevant interface carries out the discrimination o...

AI Technical Summary

Problems solved by technology

[0005] 1. There is no effective electrical isolation between the self-inspection input circuit and the open-in acquisition circuit, and the interference signal introduced by the switch input circuit can easily cause damage to the self-inspection circuit, which in turn leads to the failure to realize the self-inspection function normally

[0006] 2. The self-test signal output by the CPUIO port is a square wave signal, which is easy to be confused with the normal switch-in signal, resulting in misjudgment of self-test or switch-in malfunction

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