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Alternating current input voltage detection circuit

A technology of AC input and voltage detection, which is applied in the direction of converting AC power input to DC power output, emergency protection circuit devices, electrical components, etc., and can solve the problem of not being able to know the magnitude of the input voltage in real time

Inactive Publication Date: 2021-08-31
MORNSUN GUANGZHOU SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In practical applications, input voltage detection is a very important application. Part of the circuit is through the transformer winding, and then compared with the primary side IC to achieve the function of input undervoltage protection. However, we cannot know the magnitude of the input voltage in real time. And the input voltage belongs to the primary side signal, and in our practical application, this primary side signal needs to be given to the customer's host computer

Method used

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  • Alternating current input voltage detection circuit

Examples

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no. 1 example

[0033] Such as figure 1 Shown is the specific schematic diagram of the first embodiment of the present invention, and its components include a triangular wave self-excited oscillation circuit, an input voltage sampling circuit, a self-pulse width generating circuit and a low-pass filter circuit, and its functions will be described in detail below.

[0034] Such as figure 2Shown is the triangular wave self-excited oscillation circuit of this embodiment, including a stabilized power supply, a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R21, a capacitor C3, a capacitor C4, and a switching tube Q3, switch tube Q4 and TL431 U2, the regulated power supply is connected in series with R11 and R15 to PGND, capacitor C3 is connected in parallel to both ends of resistor R15, one end of capacitor C3 is connected to the drain of switch tube Q4 and one end of resistor R14, The gate of the switching tube Q4 is con...

no. 2 example

[0048] Such as Figure 10 Shown is the specific schematic diagram of the second embodiment of the present invention, which consists of a triangular wave self-excited oscillation circuit, an input voltage sampling circuit and a self-pulse width generation circuit. The difference is that the pulse width fed back from the primary side is directly passed to the The single-chip microcomputer detects and uses the pulse width detection function of the single-chip microcomputer to find the one-to-one correspondence between the input voltage and the pulse width. +R20) It can be seen that Vac_PEAK=Vref*D*(R17+R18+R19+R20) / R20, and the effective value is equal to dividing this peak value by 1.414.

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Abstract

The invention discloses an alternating current input voltage detection circuit, which comprises a triangular wave self-oscillation circuit, an input voltage sampling circuit, a self-pulse width generation circuit and a low-pass filter circuit, wherein the triangular wave self-oscillation circuit generates a triangular wave voltage and outputs the triangular wave voltage to the self-pulse width generation circuit; alternating-current input voltage is converted into direct-current low voltage through the input voltage sampling circuit and output to the self-pulse width generation circuit, the direct-current low voltage is compared with triangular wave voltage to obtain a square wave signal, and the square wave signal is transmitted to a secondary side through an optocoupler and can be directly sent to a single chip microcomputer for pulse width sampling, or a stable low voltage is obtained through the low-pass filter circuit, the voltage and the input voltage form a linear relation, the voltage is input to the AD sampling of the single-chip microcomputer, then the input voltage can be sampled in real time through the linear relation, the input voltage can be transmitted to the upper computer through a serial port, and the upper computer can know the magnitude of the input voltage in real time.

Description

technical field [0001] The invention relates to the field of switching power supplies, in particular to a switching power supply AC input voltage detection circuit. Background technique [0002] In switching power supply applications, the detection of AC input current has always been a headache. Since the input is an AC signal, it is difficult to sample an accurate voltage. In our practical application, we need to know the magnitude of the input voltage. To realize some important functions, such as applied to the input high voltage circuit, when the input voltage is low, we don’t want the power supply to start working. At this time, we need to sample the size of the input voltage. When the threshold value we set is not reached, the power supply will not have Output, only when the threshold is reached, the power supply will have output. In addition, the input voltage cannot be infinitely high. At this time, we can set the upper limit of the input voltage. When the upper thres...

Claims

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Application Information

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IPC IPC(8): H02M1/00H02H7/125H02M7/219H02M1/14
CPCH02M1/00H02H7/125H02H7/1252H02M7/219H02M1/14
Inventor 不公告发明人
Owner MORNSUN GUANGZHOU SCI & TECH