Electric leakage protection current measurement method via mutual inductor

Abstract

The invention discloses an electric leakage protection current measurement method via a mutual inductor. An R0, an R1 and a comparator form a hysteresis comparison circuit to adjust a threshold voltage of the comparator; if the present output voltage of the comparator is +VCC, the threshold of the comparison equals +VCC*R0 / (R0 + R1); if the present output voltage of the comparator is -VCC, the threshold of the comparison equals -VCC*R0 / (R0 + R1); the anti-phase end of the comparator is connected in series with an LC to form a resonance circuit with a hysteresis comparator, an inductor L in theresonance circuit is formed by secondary winding of the mutual inductor, when the primary current is opposite to the secondary current, an inductance value is increased, the charging / discharging speed of a capacitor is decreased, and the current magnitude and direction in the primary side can be determined. Compared with a traditional mutual inductor detection current manner, not only pure alternating current is detected, and various types of leakage currents such as pure alternating current, pulsating direct current, pure direct current and direct current superimposed alternating current canbe effectively detected.

Description

technical field [0001] The invention relates to the technical field of leakage protection, in particular to a current measurement method for applying a transformer to leakage protection. Background technique [0002] In the prior art, only the analog-to-digital conversion circuit (ADC) can be used to measure the current in the current measurement of the transformer. If the current has a negative direction and the voltage generated by the transformer coil terminal is lower than the reference ground of the ADC The voltage cannot be measured by the ADC, and when using the ADC to measure the linear voltage, it is necessary to ensure its efficiency and low distortion data, and a high-speed ADC must be used to ensure low distortion, but the circuit structure of the high-speed ADC is complex and the power consumption is generally relatively high. Big, contrary to the "green environmental protection" concept pursued by the industry today. And it is relatively troublesome to calcula...

AI Technical Summary

Problems solved by technology

[0002] In the prior art, only the analog-to-digital conversion circuit (ADC) can be used to measure the current in the current measurement of the transformer. If the current has a negative direction and the voltage generated by the transformer coil terminal is lower than the reference ground of the ADC The voltage cannot be measured by the ADC, and when using the ADC to measure the linear voltage, it is necessary to ensure its efficiency and low distortion data, and a high-speed ADC must be used to ensure low distortion, but the circuit structure of the high-speed ADC is complex and the power consumption is generally relatively high. Big, contrary to the "green environmental protection" concept pursued by the industry today

And it is relatively troublesome to calculate the effective value of the measured current

The existing technology can only detect alternating current, but the direct current pulse cannot detect direct current, ignoring the safety problem of direct current application in real life

The existing technology used in such as B-type leakage detection circuit is too expensive in the medium term, and it is necessary to use different types of circuits to detect different types of leakage forms, which makes the entire leakage detection circuit cumbersome and complicated. Not fully utilized, resulting in a great waste of resources

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