Single-phase AC voltage detection protection circuit based on mutual inductor

Abstract

The invention discloses a single-phase AC voltage detection protection circuit based on a mutual inductor. The protection circuit comprises a microcontroller, a reference voltage circuit, a current limiting circuit, a current-voltage conversion circuit, a filter circuit, a voltage amplification circuit and a waveform conversion circuit, wherein the microcontroller collects and samples the single-phase alternating-current voltage which is subjected to current limiting through the current limiting circuit, conversion through the current-voltage conversion circuit, filtering through the filter circuit and amplification through the voltage amplification circuit to obtain sampling data of the single-phase alternating-current voltage, calculates real-time single-phase alternating-current voltage, compares the real-time single-phase alternating-current voltage with a preset overvoltage value and a preset undervoltage value, and when the voltage value is higher than the overvoltage value or lower than the undervoltage value, controls the external relay driving circuit to turn off the power supply; the waveform conversion circuit converts square wave output, the microcontroller collects square waves to detect real-time frequency and a zero crossing point, and when the zero crossing point is detected, the external relay drive circuit is controlled to turn off a power supply. The protection circuit is advantaged in that an effective value of the single-phase AC voltage is detected in a real-time, high-precision and wide-range manner, and the protection circuit is controlled based on the effective value.

Description

technical field [0001] The invention relates to the technical field of control circuits, in particular to a transformer-based single-phase AC voltage detection and protection circuit. Background technique [0002] At present, with the acceleration of urbanization, the application of intelligent control of street lamps is becoming more and more extensive. At present, there are two main types of single-phase AC voltage detection schemes commonly used in street lamp single-lamp controllers: one is based on single-phase voltage transformers and diode bridge rectifier filter circuits, which convert single-phase AC voltage into approximate DC voltage Signal output; the other is a solution based on a Hall voltage sensor. [0003] However, these two solutions currently have the following problems: [0004] One is the scheme based on single-phase voltage transformer and diode bridge rectifier filter circuit. Although simple and reliable, due to the voltage drop loss of diode bridge...

AI Technical Summary

Problems solved by technology

[0004] One is the scheme based on single-phase voltage transformer and diode bridge rectifier filter circuit. Although simple and reliable, due to the voltage drop loss of diode bridge rectifier circuit, it not only has non-linearity of detection but also affects detection accuracy, and also limits voltage detection. range, there is also a large signal delay;

[0005] Second, the solution based on the Hall voltage sensor is expensive and limits its application range

[0006] The above two schemes do not do relevant protection and control based on the collected data; therefore, how to design a cost-effective AC voltage effective value detection and protection circuit scheme based on the single-phase AC voltage detection and protection circuit of the transformer will undoubtedly make the street lamp smart Single lamp controller further miniaturized

Images