Sampling control circuit based on zero crossing point detection

Abstract

The utility model discloses a sampling control circuit based on zero crossing point detection, which comprises an optocoupler U3, a resistor R33, a resistor R29, a resistor R11, a resistor R21 and a capacitor C9, a first port of the optocoupler U3 is connected with an alternating current N end, a second port of the optocoupler U3 is connected with an alternating current L end through the resistor R33 and the resistor R29, a fourth port of the optocoupler U3 is respectively connected with one end of the resistor R11 and one end of the resistor R21, and the other end of the resistor R21 is connected with the capacitor C9. The other end of the resistor R11 is connected with a VDD end, one end of the capacitor C9 is respectively connected with the other end of the resistor R21 and a chip IO port Zero, and the other end of the capacitor C9 is connected with a third port of the optocoupler U3 and is grounded, and through a zero-cross detection mechanism, accurate sampling time is ensured, so that the influence of instability of an alternating current waveform on a sampling result is avoided, and the sampling precision is greatly improved; the optical coupler and other components are used for zero-cross detection, so that interference of external electrical noise on signal acquisition can be effectively avoided, and the reliability of zero-cross detection is ensured.

Description

Technical Field

[0001] This utility model relates to the field of electrical detection technology, and in particular to a sampling control circuit based on zero-crossing detection. Background Technology

[0002] In modern electrical and automation systems, accurate measurement of AC voltage is crucial for power grid condition monitoring, load control, and power analysis. Microcontrollers (MCUs) are widely used for AC voltage sampling due to their low power consumption and high integration. However, the periodic variations in AC waveforms and the fluctuations in voltage amplitude pose challenges to ADC sampling. Specifically: 1) Direct sampling is inaccurate: When using a traditional ADC to directly sample AC voltage, the periodic variations in AC waveforms, voltage amplitude fluctuations, and voltage fluctuations caused by circuit loads may lead to sampling in areas of significant voltage variation, resulting in inaccurate measurement results. This is particularly problematic when the sampling point is misaligned with a high-variable section of the voltage waveform, potentially causing substantial errors. 2) Noise interference: AC power itself contains noise, and the operation of load equipment also contributes to noise interference during sampling. Especially when the sampling window is mismatched with the phase of the AC waveform, the measurement results may be severely affected by errors. Summary of the Invention

[0003] To address the problems existing in the prior art, the purpose of this utility model is to provide a sampling control circuit based on zero-crossing detection. By sampling near the zero-crossing point of the AC waveform, sampling is avoided when the voltage fluctuates significantly, thereby ensuring more stable and accurate sampling results.

[0004] To solve the above problems, the present invention adopts the following technical solution.

[0005] A sampling control circuit based on zero-crossing detection includes an optocoupler U3, resistors R33, R29, R11, R21, and a capacitor C9. The first port of the optocoupler U3 is connected to the AC N terminal, and the second port of the optocoupler U3 is connected to the AC L terminal through resistors R33 and R29. The fourth port of the optocoupler U3 is connected to one end of resistors R11 and R21, and the other end of resistor R11 is connected to the VDD terminal. One end of the capacitor C9 is connected to the other end of resistor R21 and the chip I / O port Zero, and the other end is connected to the third port of the optocoupler U3 and grounded.

[0006] As a further improvement of this utility model, it also includes a sampling circuit, which includes resistors R9, R16, R27, R26, and capacitor C10. Resistors R9, R16, and R27 are connected in sequence, with one end of resistor R9 connected to the sampling voltage and one end of resistor R27 grounded. Resistors R27, R26, and capacitor C10 form a loop, and the end of resistor R26 and capacitor C10 connected is connected to the Vbus port of the chip.

[0007] Beneficial effects of this utility model

[0008] Compared with existing technologies, the advantages of this utility model are:

[0009] 1. Improve sampling accuracy: By using a zero-crossing detection mechanism, the sampling timing is ensured to be accurate, thereby avoiding the influence of AC waveform instability on the sampling results and greatly improving sampling accuracy.

[0010] 2. Strong anti-interference capability: The use of components such as optocouplers for zero-crossing detection can effectively avoid interference from external electrical noise on signal acquisition and ensure the reliability of zero-crossing detection.

[0011] 3. Improve system stability: Through precise sampling control, instability caused by improper sampling window selection is avoided, thus improving the overall stability of the system. Attached Figure Description

[0012] Figure 1 This is the zero-crossing detection circuit diagram of this utility model.

[0013] Figure 2 This is a voltage sampling circuit diagram of the present invention. Detailed Implementation

[0014] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the protection scope of the present utility model.

[0015] Please see Figure 1A sampling control circuit based on zero-crossing detection includes an optocoupler U3, resistors R33, R29, R11, R21, and capacitor C9. The first port of optocoupler U3 is connected to the AC N terminal, and the second port is connected to the AC L terminal through resistors R33 and R29. The fourth port of optocoupler U3 is connected to one end of resistors R11 and R21, and the other end of resistor R11 is connected to the VDD terminal. One end of capacitor C9 is connected to the other end of resistor R21 and the chip's I / O port Zero, and the other end is connected to the third port of optocoupler U3 and grounded. The zero-crossing detection in this technical solution involves acquiring the zero-crossing signal of the AC waveform through a zero-crossing detection circuit with optocoupler U3, accurately detecting the zero-crossing point of the AC current. When the AC current passes through zero, the Zero port is inverted to a low level, thus determining the zero-crossing.

[0016] Please see Figure 2 When the microcontroller detects a zero-crossing signal, it performs ADC sampling after a certain time interval. During this period, the AC waveform tends to stabilize, providing a more accurate voltage value. The sampling circuit includes resistors R9, R16, R27, and R26, and capacitor C10. Resistors R9, R16, and R27 are connected sequentially, with one end of resistor R9 connected to the sampling voltage and one end of resistor R27 grounded. Resistors R27, R26, and capacitor C10 form a loop, and the end connected to resistor R26 and capacitor C10 is connected to the chip's Vbus port. After passing the zero-crossing point, the microcontroller's ADC module samples in the stable region, ensuring accurate sampling results. The voltage value obtained by dividing the bus voltage through resistors is input to the Vbus pin and supplied to the chip's ADC sampling port for sampling.

[0017] The above description is merely a preferred embodiment of this utility model; however, the protection scope of this utility model is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in this utility model, based on the technical solution and its improved concept, should be included within the protection scope of this utility model.

Claims

1. A zero-crossing detection based sampling control circuit, characterized by, The sampling circuit comprises a resistor R9, a resistor R16, a resistor R27, a resistor R26 and a capacitor C10, the resistor R9, the resistor R16 and the resistor R27 are connected in sequence, one end of the resistor R9 is connected to a sampling voltage, one end of the resistor R27 is grounded, the resistor R27, the resistor R26 and the capacitor C10 form a loop, and one end of the resistor R26 and the capacitor C10 is connected to a Vbus port of the chip.

2. The sampling control circuit based on zero-crossing detection according to claim 1, characterized in that: The sampling circuit comprises a resistor R9, a resistor R16, a resistor R27, a resistor R26 and a capacitor C10, the resistor R9, the resistor R16 and the resistor R27 are connected in sequence, one end of the resistor R9 is connected to a sampling voltage, one end of the resistor R27 is grounded, the resistor R27, the resistor R26 and the capacitor C10 form a loop, and one end of the resistor R26 and the capacitor C10 is connected to a Vbus port of the chip.

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