Current non-linear compensation method of residual current protection circuit breaker

Abstract

The present invention relates to a current non-linear compensation method of a residual current protection circuit breaker, pertaining to the field of the residual current protection circuit breaker.The method comprises the following steps: a current transformer converting a large alternating current at a primary side into a small current at a secondary side; outputting a direct current via rectification; inputting the direct current into an ADC to perform digital sampling via current and voltage conversion and signal conditioning; and finally performing piecewise linear fitting processing ondata digitally sampled by the ADC via a microprocessor. By modifying the ratio coefficient K value of each interval, the linear compensation of the non-linear interval of the current transformer is realized, and the current detection accuracy requirement(s) in a full current input range are met. The method does not need circuit component establishment, the cost is low, debugging, verification andproduction are more convenient, and higher precision is easier to reach; and because of the software segmentation by adopting the microprocessor, the segmentation can be finer, and the implementationis more convenient and flexible.

Description

technical field [0001] The invention belongs to the field of residual current protection circuit breakers, in particular to a current non-linear compensation method for residual current protection circuit breakers. [0002] technical background [0003] The current transformer converts a large current on the primary side into a small current on the secondary side based on the principle of electromagnetic induction. The residual current protection circuit breaker detects the load current through the current transformer, and performs corresponding overload long-time delay, short-circuit short-time delay, and short-circuit instantaneous protection. Due to the existence of current transformer iron core saturation, eddy current, hysteresis and excitation current, the input and output transmission characteristics of current transformer are nonlinear, which greatly affects the current measurement accuracy. [0004] For the problem of nonlinear transformation, the main idea is to pr...

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Problems solved by technology

[0005] Due to the solution through hardware circuits, it is necessary to increase the corresponding circuits and components, resulting in a corresponding increase in cost; to improve the linear accuracy requirements, it is necessary to gate more operational amplifiers with different gains, and the hardware complexity will be greatly increased. At the same time, the circuit The temperature drift of components has uncertain factors, which will prolong the R & D design and debugging test cycle; the increase of circuit components will occupy the PCB wiring area, resulting in an increase in the cost of the PCB circuit board, and also increases the production risk

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