Non-isolated voltage detection circuit

Abstract

The utility model relates to the technical field of direct current power supply and distribution, and particularly provides a non-isolated voltage detection circuit, which comprises a sampling module, a voltage clamping module, a first voltage sampling point A and a second voltage sampling point B. The sampling module comprises a resistor R1, a resistor R2 and a resistor R3. The voltage clamping module comprises a rectifier diode D1, a switching diode D2 and a switching diode D3, and a first voltage sampling point A is arranged between the output end of the rectifier diode D1 and the ground; a resistor R4 is connected in parallel between the switching diode D3 and the switching diode D2, and a second voltage sampling point B is arranged at the other end of the resistor R4; the device is reasonable in design, simple in structure, passive in overall design, free of extra power supply in operation, capable of reducing the aging problem of devices, high in reliability and suitable for long-term stable work; the circuit structure does not need complex devices, is low in manufacturing cost, and is suitable for large-scale popularization and application in the market.

Description

Technical Field

[0001] This utility model relates to the field of DC power supply and distribution technology, specifically to a non-isolated voltage detection circuit. Background Technology

[0002] For areas with insufficient power grid stability, top-loading washing machines will be equipped with AC voltage detection functionality.

[0003] Currently, voltage detection is commonly achieved using optocouplers. Alternating current is stepped down by a voltage divider circuit, converting it into a low-voltage signal suitable for the optocoupler's operation. This signal drives an LED inside the optocoupler, which emits light that is received by a photosensitive element. The optical signal is then converted into an electrical signal. The current signal generated by the photosensitive element is processed by operational amplifiers and other circuits to recover a voltage signal proportional to the input voltage.

[0004] A published Chinese patent, publication number CN216718534U, discloses a voltage sampling circuit, including an optocoupler and a voltage divider circuit. The first end of the optocoupler's emitter is connected to the positive terminal of a battery; the second end of the optocoupler's emitter is connected to the negative terminal of the battery; the first end of the optocoupler's receiver is connected to a power supply; the second end of the optocoupler's receiver is connected to the first end of the first resistor in the voltage divider circuit; the second end of the second resistor in the voltage divider circuit is grounded; and the second end of the first resistor and the first end of the second resistor are connected and used as the sampling terminal for the voltage. This optocoupler-isolated voltage sampling scheme suffers from the problem that the optocoupler's current transfer ratio (CTR) changes with temperature and aging, leading to errors and poor linearity, thus affecting the sampling accuracy of the voltage signal. Utility Model Content

[0005] In view of the shortcomings of the prior art described above, the purpose of this utility model is to provide a non-isolated voltage detection circuit. By setting a resistive voltage divider module, the resistive structure can divide the AC input voltage. Pure resistive voltage division has no nonlinear distortion, ensuring that the sampled voltage is strictly proportional to the input voltage, reducing measurement errors, improving the sampling accuracy of the voltage signal, and thus improving the accuracy of voltage detection. This solves the problem of poor linearity in the existing optocoupler-isolated voltage sampling scheme.

[0006] To achieve the above and other related objectives, this utility model provides a non-isolated voltage detection circuit, including a sampling module, a voltage clamping module, a first voltage sampling point A, and a second voltage sampling point B;

[0007] The sampling module includes resistors R1, R2, and R3 connected in series, with the other end of resistor R1 connected to AC-N.

[0008] The voltage clamping module includes a rectifier diode D1, a switching diode D2, and a switching diode D3. The input terminal of the rectifier diode D1 is connected to a resistor R3, and the output terminal is grounded. The first voltage sampling point A is located between the output terminal of the rectifier diode D1 and ground.

[0009] The output terminal of the switching diode D3 is connected to the input terminal of the switching diode D2. The input terminal of the switching diode D3 is grounded, and the output terminal of the switching diode D2 is connected to a +5V high level. The first voltage sampling point A is connected to both the input terminals of the switching diode D3 and the input terminal of the switching diode D2. The voltage range is limited by the clamping effect of the switching diodes D2 and D3.

[0010] A resistor R4 is connected in parallel between the output terminal of the switching diode D3 and the input terminal of the switching diode D2, and the second voltage sampling point B is located at the other end of the resistor R4.

[0011] In one embodiment of this utility model, an aluminum electrolytic capacitor C2 is connected between the first voltage sampling point A and the second voltage sampling point B.

[0012] In one embodiment of this utility model, a patch capacitor C1 is connected in parallel to the second voltage sampling point B, and the other end of the patch capacitor C1 is grounded.

[0013] In one embodiment of this utility model, a resistor R5 is provided between the first voltage sampling point A and the ground.

[0014] As described above, the non-isolated voltage detection circuit of this utility model has the following beneficial effects:

[0015] 1. By setting up a resistive voltage divider module, the resistive structure can divide the AC input voltage. The pure resistive voltage divider has no nonlinear distortion, ensuring that the sampled voltage is strictly proportional to the input voltage, reducing measurement errors, improving the sampling accuracy of the voltage signal, and thus improving the accuracy of voltage detection.

[0016] 2. By setting multiple diodes to rectify and clamp the input voltage, the voltage passing through the sampling circuit is limited to a safe range, which can prevent the sampling voltage fluctuation from exceeding the normal operating range, thereby protecting the electronic components in the sampling circuit from damage by high voltage surges and improving the service life of the detection circuit.

[0017] 3. This invention features a reasonable overall design and simple structure. The resistive voltage divider module has minimal bandwidth limitation during voltage detection, achieving an overall response speed at the MHz level, resulting in fast response and excellent detection performance. The resistive voltage divider module eliminates nonlinear distortion, improving voltage sampling accuracy. The voltage clamping module design prevents sampling voltage fluctuations from exceeding the normal operating range. This circuit adopts a passive design, requiring no additional power supply, reducing component aging issues, and ensuring high reliability, making it suitable for long-term stable operation. The circuit structure requires no complex components, resulting in low manufacturing costs and making it suitable for large-scale market application. Attached Figure Description

[0018] Figure 1 The diagram shown is a schematic diagram of the circuit principle of this utility model.

[0019] Figure 2 The diagram shows the implementation principle of this utility model applied to a pulsator washing machine. Detailed Implementation

[0020] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification.

[0021] Please see Figures 1-2 This utility model provides a non-isolated voltage detection circuit, including a sampling module, a voltage clamping module, a first voltage sampling point A, and a second voltage sampling point B;

[0022] The sampling module includes resistors R1, R2, and R3 connected in series. All resistors R1, R2, and R3 are surface-mount resistors with a resistance of 220KΩ. The other end of resistor R1 is connected to AC-N. By setting up a resistive voltage divider module, the resistor structure can divide the AC input voltage. Pure resistive voltage division has no nonlinear distortion, ensuring that the sampled voltage is strictly proportional to the input voltage, reducing measurement errors, improving the sampling accuracy of the voltage signal, and thus improving the accuracy of voltage detection.

[0023] The voltage clamping module includes a rectifier diode D1, a switching diode D2, and a switching diode D3. The input terminal of the rectifier diode D1 is connected to a resistor R3, and the output terminal is grounded. The first voltage sampling point A is located between the output terminal of the rectifier diode D1 and ground, and a resistor R5 is provided between the first voltage sampling point A and ground.

[0024] The output terminal of switching diode D3 is connected to the input terminal of switching diode D2. The input terminal of switching diode D3 is grounded, and the output terminal of switching diode D2 is connected to a +5V high level. The first voltage sampling point A is connected to both the input terminals of switching diode D3 and switching diode D2, and the voltage is clamped by switching diodes D2 and D3 to limit the voltage range. A resistor R4 is connected in parallel between the output terminal of switching diode D3 and the input terminal of switching diode D2, and the second voltage sampling point B is located at the other end of resistor R4. An aluminum electrolytic capacitor C2 is connected between the first voltage sampling point A and the second voltage sampling point B. By using multiple diodes to rectify and clamp the input voltage, the voltage passing through the sampling circuit is limited to a safe range, preventing the sampling voltage fluctuation from exceeding the normal operating range. This protects the electronic components in the sampling circuit from high voltage surges and extends the service life of the detection circuit.

[0025] In practical implementation, this application divides the AC voltage by setting the resistance values ​​of resistors R1, R2, and R3. When the pulsator washing machine's control board is turned on, the AC-N voltage is between 0.7VAC and AC-N.

[0026] At 5.7VAC, the AC current will flow sequentially through resistor R1, resistor R2, resistor R3, rectifier diode D1, first voltage sampling point A, circuit R5, and finally return to ground GND.

[0027] When the AC-N voltage is greater than 5.7VAC, the AC current will flow through resistor R1, resistor R2, resistor R3, rectifier diode D1, first voltage sampling point A, switching diode D2 and finally return to the +5V high level.

[0028] When the AC-N voltage is less than 0.7VAC, the AC current will flow through resistors R1, R2, and R3 in sequence until it is cut off at rectifier diode D1. The voltage at the first voltage sampling point A is regulated and filtered by aluminum electrolytic capacitor C2 to obtain the voltage at the second voltage sampling point B. The MCU can calculate the magnitude of the input AC voltage by acquiring the second voltage sampling point B.

[0029] This invention designs different voltage flow paths for different voltage ranges, and with the help of two sampling points, it can obtain sampling values ​​for different voltage ranges, thereby detecting the magnitude of the input AC voltage and ensuring the working stability of the pulsator washing machine.

[0030] A surface-mount capacitor C1 is connected in parallel at the second voltage sampling point B, with the other end of C1 grounded. In a non-isolated voltage detection circuit, C1 stores charge in the form of electric field energy, which is used to absorb interference pulse signals, smooth surge current, and store electrical energy. When the voltage across C1 is lower than the external circuit voltage or power supply voltage, the external circuit or power supply voltage will charge it until it is fully charged, even if the voltage across C1 is equal to the external circuit voltage. When the voltage across C1 is higher than the external circuit voltage or power supply voltage, C1 discharges to the external circuit until its voltage is equal to the external circuit voltage. If the external circuit voltage is zero, C1 will completely discharge its stored energy, i.e., the voltage across C1 will be zero. By charging and discharging C1, it can be used for voltage delay, absorption, filtering, reset, and switching in the circuit, improving the stability of the voltage passing through the circuit.

[0031] In summary, this invention features a reasonable overall design and simple structure. The resistive voltage divider module has minimal bandwidth limitations during voltage detection, achieving an overall response speed at the MHz level, resulting in fast response and excellent detection performance. The resistive voltage divider module eliminates nonlinear distortion, improving voltage sampling accuracy. The voltage clamping module design prevents sampling voltage fluctuations from exceeding the normal operating range. This circuit employs a passive design, requiring no external power supply, reducing component aging issues, and ensuring high reliability suitable for long-term stable operation. The circuit structure requires no complex components, resulting in low manufacturing costs and making it suitable for large-scale market application. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and possesses high industrial applicability.

[0032] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A non-isolated voltage detection circuit, characterized in that: Includes a sampling module, a voltage clamping module, a first voltage sampling point A, and a second voltage sampling point B; The sampling module includes resistors R1, R2, and R3 connected in series, with the other end of resistor R1 connected to AC-N. The voltage clamping module includes a rectifier diode D1, a switching diode D2, and a switching diode D3. The input terminal of the rectifier diode D1 is connected to a resistor R3, and the output terminal is grounded. The first voltage sampling point A is located between the output terminal of the rectifier diode D1 and ground. The output terminal of the switching diode D3 is connected to the input terminal of the switching diode D2. The input terminal of the switching diode D3 is grounded, and the output terminal of the switching diode D2 is connected to a +5V high level. The first voltage sampling point A is connected to both the input terminals of the switching diode D3 and the input terminal of the switching diode D2. The voltage range is limited by the clamping effect of the switching diodes D2 and D3. A resistor R4 is connected in parallel between the output terminal of the switching diode D3 and the input terminal of the switching diode D2, and the second voltage sampling point B is located at the other end of the resistor R4.

2. The non-isolated voltage detection circuit according to claim 1, characterized in that: An aluminum electrolytic capacitor C2 is connected between the first voltage sampling point A and the second voltage sampling point B.

3. The non-isolated voltage detection circuit according to claim 1, characterized in that: A surface-mount capacitor C1 is connected in parallel at the second voltage sampling point B, and the other end of the surface-mount capacitor C1 is grounded.

4. The non-isolated voltage detection circuit according to claim 1, characterized in that: A resistor R5 is provided between the first voltage sampling point A and the ground.

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