CN218512522U

CN218512522U - Simple AC voltage monitoring circuit based on triode drive

Info

Publication number: CN218512522U
Application number: CN202222479414.XU
Authority: CN
Inventors: 薛天威; 张小群; 凌立本
Original assignee: Leibo Electric Changzhou Co ltd
Current assignee: Leibo Electric Changzhou Co ltd
Priority date: 2022-09-20
Filing date: 2022-09-20
Publication date: 2023-02-21
Anticipated expiration: 2032-09-20

Abstract

The utility model relates to a voltage monitoring technical field especially relates to a simple and easy AC voltage monitoring circuit based on triode drive, including AC voltage, RC filter circuit, triode Q3, MCU circuit and AC sensor, AC voltage's output is connected on RC filter circuit's the input, RC filter circuit's output is connected on triode Q3's the input, triode Q3's output is connected on the input of MCU circuit. Through dividing the AC voltage, drive switching transistor Q3 through this voltage afterwards again, can produce the PWM waveform afterwards, handle through the software program, can 1ms be detection period, through the judgement to the high-low level, thereby discern the PWM waveform, it has high level and low level to appear to monitor to have or not within 20ms, thereby judge whether have AC alternating voltage's existence, reached and just can monitor the effect whether the AC power is opened a way with only using a circuit, make the speed of detecting faster, the degree of accuracy is higher.

Description

Simple AC voltage monitoring circuit based on triode drive

Technical Field

The utility model relates to a voltage monitoring technical field especially relates to a simple and easy AC voltage monitoring circuit based on triode drive.

Background

In a traditional rectifying and filtering circuit, because a large capacitor is contained in the circuit, when the circuit is electrified for the first time, the capacitor is equivalent to a short circuit, so that a large charging current can be caused, in order to limit the charging current, a PTC resistor is added, after the capacitor charging of 2s and the like is completed after the electrification, the PTC resistor is completed, and then a relay K1 is closed through software to short circuit the PTC resistor, so that the electrifying process of the whole circuit is realized, however, when an AC voltage is cut off, the LN input end in the circuit does not have voltage, but because of the existence of the large capacitor, the rectified and filtered DC voltage is not immediately 0 but slowly drops, at this time, a problem exists, when the DC voltage drops to 100V, a rear MCU still has electricity, at this time, the relay K1 is not cut off, when the AC voltage is switched on again, the rectified and filtered DC voltage is 310V, so that a voltage difference between the large capacitor and a rectifying bridge has 210V, and the internal resistance of the section of a conducting wire is very small, and the impact current on a bus is very large, so that the relay is adhered;

a solution is then needed to detect whether the AC voltage is disconnected and to open the relay K1 in time when the AC voltage is disconnected, protecting the relay and the following circuits from damage due to excessive inrush current.

SUMMERY OF THE UTILITY MODEL

The utility model aims at solving the shortcoming that exists among the prior art, and the simple and easy AC voltage monitoring circuit based on triode drive that proposes.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a simple AC voltage monitoring circuit based on triode driving comprises an AC voltage, an RC filter circuit, a triode Q3, an MCU circuit and an AC sensor, wherein the output end of the AC voltage is connected to the input end of the RC filter circuit, the output end of the RC filter circuit is connected to the input end of the triode Q3, the output end of the triode Q3 is connected to the input end of the MCU circuit, and in addition, the output end of the triode Q3 is also connected to the input end of the AC sensor;

the output end of the AC voltage is connected with a resistor R137, the output end of the resistor R137 is connected with a test point TP54, the output end of the test point TP54 is connected with a resistor R138, the output end of the resistor R138 is connected with a test point TP55, the output end of the test point TP55 is connected with a resistor R139, and the output end of the resistor R139 is connected with the input end of the RC filter circuit.

Preferably, the resistor R137, the resistor R138 and the resistor R139 are R-1206-330K-F patch resistors.

Preferably, the RC filter circuit includes a resistor R140, an input end of the resistor R140 is connected to an output end of the resistor R139, two ends of the resistor R140 are connected in parallel to a capacitor C95, an input end of the capacitor C95 is connected to a test point TP86, the resistor R140 and the resistor C95 form a parallel circuit, one end of the parallel circuit is connected to a ground terminal GND, and the other end is connected to the base stage of the transistor Q3.

Preferably, the resistor R140 is an R-0603-5.1K-F patch resistor, the capacitor C95 is a C-0603-1nF-50V patch capacitor, and the triode Q3 is an NPN MMBT3904 switching transistor.

Preferably, a collector of the triode Q3 is connected with a resistor R141, the resistor R141 is connected to an output end of the MCU circuit, an ADC input of the MCU circuit is 3.3V, the collector of the triode Q3 is further connected with a test point TP83, an output end of the test point TP83 is connected with a capacitor C96, the other end of the capacitor C96 is connected to an emitter of the triode Q3, the capacitor C96 and the triode Q3 form a parallel circuit, one end of the parallel circuit is connected to a ground terminal GND, the other end is connected with a resistor R142, an output end of the resistor R142 is connected with a test point TP84, and an output end of the test point TP84 is connected to an input end of the AC sensor.

Preferably, the type of the resistor R141 is R-0603-5.1K-F patch resistor, the type of the resistor R142 is R-0603-100K-F patch resistor, and the type of the capacitor C96 is C-0603-1nF-50V patch capacitor.

The utility model has the advantages that: the AC voltage is divided by a hardware circuit, then the voltage drives a switch transistor Q3, a PWM waveform can be generated, the PWM waveform can be identified by judging high and low levels in 1ms as a detection period through software program processing, the existence of the AC voltage is monitored, if the high and low levels are monitored within 20ms, the AC alternating voltage is represented, and if the high and low levels are not detected within 20ms, the AC alternating voltage is judged to be absent, so that the effect of monitoring whether the AC power supply is open or not by using one circuit is achieved, the detection speed is higher, and the accuracy is higher.

Drawings

Fig. 1 is the utility model provides a simple and easy AC voltage monitoring circuit's based on triode drive circuit principle schematic diagram.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments.

Those not described in detail in this specification are within the skill of the art.

The first embodiment is as follows: referring to fig. 1, a simple AC voltage monitoring circuit based on triode drive includes an AC voltage, an RC filter circuit, a triode Q3, an MCU circuit, and an AC sensor, wherein an output end of the AC voltage is connected to an input end of the RC filter circuit, an output end of the RC filter circuit is connected to an input end of the triode Q3, an output end of the triode Q3 is connected to an input end of the MCU circuit, and an output end of the triode Q3 is also connected to an input end of the AC sensor;

wherein, the output end of the AC voltage is connected with a resistor R137, the output end of the resistor R137 is connected with a test point TP54, the output end of the test point TP54 is connected with a resistor R138, the output end of the resistor R138 is connected with a test point TP55, the output end of the test point TP55 is connected with a resistor R139, the output end of the resistor R139 is connected with the input end of the RC filter circuit, the types of the resistor R137, the resistor R138 and the resistor R139 are R-1206-330K-F chip resistors, the RC filter circuit comprises a resistor R140, the input end of the resistor R140 is connected with the output end of the resistor R139, two ends of the resistor R140 are connected with a capacitor C95 in parallel, the input end of the capacitor C95 is connected with a test point TP86, the resistor R140 and the resistor C95 form a parallel circuit, and one end of the parallel circuit is connected with a grounding end GND, the other end of the resistor R140 is connected with a base level of the triode Q3, the model of the resistor R140 is R-0603-5.1K-F patch resistor, the model of the capacitor C95 is C-0603-1nF-50V patch capacitor, the model of the triode Q3 is an NPN type MMBT3904 switch transistor, the collector of the triode Q3 is connected with a resistor R141, the resistor R141 is connected with the output end of the MCU circuit, the ADC input of the MCU circuit is 3.3V, the collector of the triode Q3 is also connected with a test point TP83, the output end of the test point TP83 is connected with a capacitor C96, the other end of the capacitor C96 is connected with the emitter of the triode Q3, the capacitor C96 and the triode Q3 form a parallel circuit, one end of the parallel circuit is connected with a grounding terminal TP, the other end of the parallel circuit is connected with a resistor R142, the output end of the resistor R142 is connected with a test point 84, the output end of the test point TP84 is connected to the input end of the AC sensor, the type of the resistor R141 is R-0603-5.1K-F patch resistor, the type of the resistor R142 is R-0603-100K-F patch resistor, and the type of the capacitor C96 is C-0603-1nF-50V patch capacitor. The AC voltage is transmitted to the RC filter circuit through a plurality of resistors, the AC voltage is divided by the plurality of resistors, then the switching transistor Q3 is driven through the AC voltage, then a PWM waveform can be generated, then software processing is carried out, 1ms is used as a detection period, and the PWM waveform is identified through judgment of high and low levels, so that whether the AC voltage exists is monitored, if the high level and the low level appear within 20ms (the period set value is adjustable), the AC alternating voltage is represented, if the high level and the low level do not appear within 20ms (the period set value is adjustable), the AC alternating voltage is judged to be not existed, and therefore the effect that whether the AC power supply is open-circuited or not can be monitored by only one circuit is achieved, the detection speed is higher, and the accuracy is higher.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and for simplicity of description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically limited otherwise.

The above, only be the embodiment of the preferred of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art is in the technical scope of the present invention, according to the technical solution of the present invention and the utility model, which are designed to be replaced or changed equally, all should be covered within the protection scope of the present invention.

Claims

1. A simple AC voltage monitoring circuit based on triode driving comprises an AC voltage, an RC filter circuit, a triode Q3, an MCU circuit and an AC sensor, and is characterized in that the output end of the AC voltage is connected to the input end of the RC filter circuit, the output end of the RC filter circuit is connected to the input end of the triode Q3, the output end of the triode Q3 is connected to the input end of the MCU circuit, and in addition, the output end of the triode Q3 is also connected to the input end of the AC sensor;

2. The simple AC voltage monitoring circuit based on triode drive as claimed in claim 1, wherein the types of the resistor R137, the resistor R138 and the resistor R139 are all R-1206-330K-F chip resistors.

3. The simple AC voltage monitoring circuit based on the triode drive as claimed in claim 1, wherein the RC filter circuit comprises a resistor R140, the input end of the resistor R140 is connected to the output end of the resistor R139, a capacitor C95 is connected in parallel to two ends of the resistor R140, the input end of the capacitor C95 is connected to the test point TP86, the resistor R140 and the capacitor C95 form a parallel circuit, one end of the parallel circuit is connected to the ground terminal GND, and the other end of the parallel circuit is connected to the base stage of the triode Q3.

4. The simple AC voltage monitoring circuit based on the triode drive as claimed in claim 3, wherein the resistor R140 is a R-0603-5.1K-F patch resistor, the capacitor C95 is a C-0603-1nF-50V patch capacitor, and the triode Q3 is an NPN MMBT3904 switching transistor.

5. The simple AC voltage monitoring circuit based on the triode drive as claimed in claim 1, wherein a resistor R141 is connected to a collector of the triode Q3, the resistor R141 is connected to an output end of the MCU circuit, an ADC input of the MCU circuit is 3.3V, the collector of the triode Q3 is further connected to a test point TP83, an output end of the test point TP83 is connected to a capacitor C96, the other end of the capacitor C96 is connected to an emitter of the triode Q3, the capacitor C96 and the triode Q3 form a parallel circuit, one end of the parallel circuit is connected to a ground end GND, the other end of the parallel circuit is connected to a resistor R142, an output end of the resistor R142 is connected to a test point TP84, and an output end of the test point TP84 is connected to an input end of the AC sensor.

6. The simple AC voltage monitoring circuit based on triode drive as claimed in claim 5, wherein the resistor R141 is R-0603-5.1K-F chip resistor, the resistor R142 is R-0603-100K-F chip resistor, and the capacitor C96 is C-0603-1nF-50V chip capacitor.