A detection circuit and electrical equipment

Abstract

This utility model discloses a detection circuit and an electrical device. The detection circuit is configured to correspond one-to-one with the phase lines of an AC power supply, including: a voltage divider module, comprising at least one voltage divider resistor, the input of which is connected to the corresponding phase line of the AC power supply; an optocoupler, the first terminal of which is connected to the output of the voltage divider module, and the second terminal connected to the neutral line; the first terminal of which is connected to a voltage source through a detection resistor, and the second terminal grounded; a first capacitor is disposed between the first and second terminals of the optocoupler's output; and a controller (MCU), connected between the detection resistor and the first terminal of the optocoupler's output, used to determine the on and off times of the optocoupler based on the voltage value on the optocoupler's output, and further predict the zero-crossing point based on the symmetry of the voltage waveform input to the optocoupler. This utility model improves detection accuracy and enables early prediction of zero-crossing points.

Description

Technical Field

[0001] This utility model relates to the field of electronic power technology, and more specifically, to a detection circuit and an electrical device. Background Technology

[0002] In some electrical appliances (such as air conditioners), motors are widely used in compressors and other drive devices. To reduce current surges, AC zero-crossing interruption control is crucial, improving system stability and reliability. However, zero-crossing interruption control relies on accurate zero-crossing detection. Existing zero-crossing detection schemes generally only detect a relatively wide range, have low accuracy, and cannot predict the zero-crossing point in advance.

[0003] There is currently no effective solution to the problems of low accuracy and detection lag in existing zero-crossing detection schemes. Utility Model Content

[0004] This utility model provides a detection circuit and electrical equipment to solve the problems of low accuracy and detection lag in the existing zero-crossing detection scheme.

[0005] To solve the above-mentioned technical problems, this utility model provides a detection circuit, which is configured to correspond one-to-one with the phase lines of the AC power supply. The detection circuit includes:

[0006] A voltage divider module includes at least one voltage divider resistor whose input terminal is connected to the corresponding phase line of the AC power supply;

[0007] An optocoupler, wherein the first terminal of its input side is connected to the output terminal of the voltage divider module, the second terminal of its input side is connected to the neutral wire, the first terminal of its output side is connected to the voltage source through a sensing resistor, the second terminal of its output side is grounded, and a first capacitor is provided between the first terminal and the second terminal of the output side of the optocoupler.

[0008] The controller MCU is connected between the detection resistor and the first terminal of the output side of the optocoupler. It is used to determine the turn-on and turn-off times of the optocoupler based on the voltage value output between the detection resistor and the first terminal of the output side of the optocoupler, and then predict the zero-crossing point based on the turn-on time, the turn-off time and the symmetry of the voltage waveform input to the optocoupler.

[0009] Furthermore, the detection circuit also includes:

[0010] A protection resistor is disposed between the first terminal and the second terminal on the input side of the optocoupler.

[0011] Furthermore, the detection circuit also includes:

[0012] The second capacitor is disposed between the first terminal on the output side and the second terminal on the input side of the optocoupler.

[0013] Furthermore, the detection circuit also includes:

[0014] The first diode has its anode connected to the second terminal on the input side of the optocoupler, and its cathode connected to the first terminal on the input side of the optocoupler.

[0015] Furthermore, the detection circuit also includes:

[0016] The second diode is disposed between the input terminal of the voltage divider module and the corresponding phase line of the AC power supply.

[0017] This utility model also provides an electrical device, including a motor and the aforementioned detection circuit.

[0018] Furthermore, the electrical equipment is an air conditioner.

[0019] By applying the technical solution of this utility model, an optocoupler is set on each phase line of the AC power supply. The turn-on and turn-off times of the optocoupler are determined by the voltage at the detection port on the output side of the optocoupler. Then, the zero-crossing point is predicted based on the turn-on and turn-off times of the optocoupler and the symmetry of the voltage waveform input to the optocoupler. Compared with the prior art, which can only detect a wide range, this embodiment has higher detection accuracy, can obtain a precise zero-crossing point, and can make advance predictions, avoiding the problem of control lag caused by zero-crossing detection lag. Attached Figure Description

[0020] Figure 1 This is a structural block diagram of the detection circuit according to an embodiment of the present utility model;

[0021] Figure 2 The voltage waveform of the optocoupler input according to an embodiment of the present invention is shown.

[0022] Figure 3 This is a structural diagram of a detection circuit according to another embodiment of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0024] The terminology used in the embodiments of this utility model is for the purpose of describing particular embodiments only and is not intended to limit the utility model. The singular forms “a,” “the,” and “the” used in the embodiments of this utility model and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0025] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0026] It should be understood that although the terms "first," "second," etc., may be used to describe capacitors in the embodiments of this utility model, these capacitors should not be limited to these terms. These terms are only used to distinguish capacitors located in different positions. For example, without departing from the scope of the embodiments of this utility model, a first capacitor may also be referred to as a second capacitor, and similarly, a second capacitor may also be referred to as a first capacitor.

[0027] Depending on the context, the words “if” or “suppose” as used here can be interpreted as “when” or “in response to determination” or “in response to detection.” Similarly, depending on the context, the phrases “if determination” or “if detection (of the stated condition or event)” can be interpreted as “when determination” or “in response to determination” or “when detection (of the stated condition or event)” or “in response to detection (of the stated condition or event).”

[0028] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0029] The optional embodiments of this utility model are described in detail below with reference to the accompanying drawings.

[0030] Example 1

[0031] In some electrical appliances (such as air conditioners), motors are widely used in compressors and other drive devices. To reduce current surges, AC zero-crossing interruption control is crucial, improving system stability and reliability. However, zero-crossing interruption control relies on accurate zero-crossing detection, and existing zero-crossing detection schemes are complex and have low accuracy.

[0032] To address the issues of low accuracy and detection lag in existing zero-crossing detection schemes, this embodiment provides a detection circuit. Figure 1 The block diagram of the detection circuit according to an embodiment of the present invention shows that the detection circuit is configured in a one-to-one correspondence with the phase lines of the AC power supply, that is, a detection circuit is configured for each phase line of the AC power supply, such as... Figure 1 As shown, the detection circuit includes: a voltage divider module 10, including at least one voltage divider resistor, whose input terminal is connected to the corresponding phase line L of the AC power supply; an optocoupler 20, whose first terminal 1 on the input side is connected to the output terminal of the voltage divider module 10, its second terminal 2 on the input side is connected to the neutral line N, its first terminal on the output side is connected to the voltage source VCC through the detection resistor Rx, its second terminal on the output side is grounded, and a first capacitor C1 is provided between the first terminal 3 and the second terminal 4 on the output side of the optocoupler 20; and a controller MCU, connected to the detection port between the detection resistor Rx and the first terminal on the output side of the optocoupler 20, used to determine the on-time and off-time of the optocoupler based on the voltage value output between the detection resistor Rx and the first terminal on the output side of the optocoupler 20, and then predict the zero-crossing point based on the on-time and off-time of the optocoupler and the symmetry of the voltage input to the optocoupler.

[0033] The waveform of the input voltage of the corresponding phase line L of the AC power supply is a sine wave. After the sine wave is divided by the voltage divider module 10, it is input to the optocoupler. Figure 2 The voltage waveform diagram of the optocoupler input according to an embodiment of this utility model is shown, where the solid line represents the voltage waveform when the optocoupler is turned on, and the dashed line represents the filtered voltage waveform or the voltage waveform when the optocoupler is not turned on. Figure 2As shown, since the voltage of the input optocoupler gradually increases from zero over time, the input side of the optocoupler is turned off before reaching the optocoupler's turn-on voltage threshold, which in turn turns off the output side of the optocoupler. A closed loop cannot be formed between the power supply VCC, the sensing resistor, and the reference ground GND, resulting in a low voltage output between the sensing resistor Rx and the first terminal of the output side of the optocoupler 20. When the optocoupler's turn-on voltage threshold is reached, the input side of the optocoupler turns on, which in turn turns on the output side of the optocoupler. A closed loop is formed between the power supply VCC, the sensing resistor, and the reference ground GND, resulting in a high voltage output between the sensing resistor Rx and the first terminal of the output side of the optocoupler 20. Therefore, based on the voltage value detected by the controller MCU, it can be determined whether the optocoupler 20 is on, as well as the on and off times. Furthermore, the first zero-crossing point and the second zero-crossing point can be calculated based on the on-time of the optocoupler.

[0034] In this embodiment, the detection circuit has an optocoupler installed on each phase line of the AC power supply. The on and off times of the optocoupler are determined by the voltage at the detection port on the output side of the optocoupler. Then, the zero-crossing point is predicted based on the on and off times of the optocoupler and the symmetry of the voltage waveform input to the optocoupler. Compared with the prior art, which can only detect a wide range, this embodiment has higher detection accuracy, can obtain a precise zero-crossing point, and can make advance predictions, avoiding the problem of control lag caused by zero-crossing detection lag.

[0035] Figure 3 Here is a structural diagram of the detection circuit according to another embodiment of the present invention, as shown below. Figure 3 As shown, the voltage divider module includes four resistors: R1 (first resistor), R2 (second resistor), R3 (third resistor), and R4 (fourth resistor).

[0036] To prevent excessive current from flowing into the optocoupler, the circuit also includes a protection resistor R5, which is placed between the first terminal 1 and the second terminal 2 on the input side of the optocoupler to shunt the current and reduce the current flowing into the input side of the optocoupler.

[0037] In order to achieve the filtering effect and ensure the accuracy of the voltage flowing into the optocoupler, the above detection circuit also includes a second capacitor C2, which is disposed between the first terminal 1 on the output side and the second terminal 2 on the input side of the optocoupler.

[0038] To limit the direction of the current and prevent the second capacitor from reverse charging the optocoupler, the detection circuit further includes a first diode D1, whose anode is connected to the second terminal 2 on the input side of the optocoupler and whose cathode is connected to the first terminal 1 on the input side of the optocoupler.

[0039] To filter out negative voltage, the detection circuit also includes a second diode D2, which is disposed between the input terminal of the voltage divider module 10 and the corresponding phase line L of the AC power supply.

[0040] In this embodiment, the controller MCU is also used to detect whether the phase sequence is normal based on the delay between the turn-on times or the delay between the turn-off times of the optocouplers corresponding to the preceding and following phase lines. For example, under normal phase sequence conditions, the turn-on time of the optocoupler corresponding to phase L1 is 5-9 ms earlier than the turn-on time of the optocoupler corresponding to phase L2, and the turn-off time of the optocoupler corresponding to phase L1 is 5-9 ms earlier than the turn-off time of the optocoupler corresponding to phase L2. Similarly, the turn-on time of the optocoupler corresponding to phase L2 is 5-9 ms earlier than the turn-on time of the optocoupler corresponding to phase L3, and the turn-off time of the optocoupler corresponding to phase L2 is 5-9 ms earlier than the turn-off time of the optocoupler corresponding to phase L3. Therefore, the normality of the three-phase sequence can be determined based on the turn-on or turn-off times of the optocouplers corresponding to the preceding and following phase lines.

[0041] In this embodiment, the controller MCU is also connected to the drive circuit of the electrical equipment. After predicting the zero-crossing point, the controller MCU sends a signal to the drive circuit at the zero-crossing point to control the relay to switch or close, or to control the motor or other equipment.

[0042] In summary, the detection circuit of this embodiment includes the following components: a voltage divider module, an optocoupler, and a controller MCU. The controller MCU is also connected to the drive circuit of the electrical equipment.

[0043] Voltage divider module: Converts the original AC power supply voltage to a suitable AC voltage through resistor division.

[0044] Optocoupler: The optocoupler will conduct when the input voltage reaches a certain value. Capacitor C2 between the two terminals on the input side of the optocoupler acts as a filter, diode D1 between the two terminals limits the current direction to prevent capacitor C2 from reverse charging the optocoupler, and resistor R5 acts as a voltage divider and current limiter.

[0045] The controller MCU calculates the zero-crossing point by detecting the time interval between the on and off moments of the optocouplers. At the zero-crossing point, it sends a control signal to control the drive circuit, thereby issuing signals to control motors and other equipment. The MCU also detects whether the phase sequence is normal by measuring the delay between the on or off moments of the corresponding optocouplers on the preceding and following phase lines.

[0046] Drive circuit: The drive circuit amplifies the level control signal sent by the controller MCU to a signal sufficient to drive the motor and other equipment. When it is necessary to turn the relay on or off, the control unit receives the start signal, waits for the AC voltage zero-crossing detection circuit to detect the zero-crossing signal, and then controls the relay to switch on or off, or controls the motor and other equipment.

[0047] The detection circuit in this embodiment achieves the technical effect of integrating phase sequence detection and AC zero-crossing switching control through integrated design, reducing system complexity, improving control accuracy and system stability, and solving the problems of dispersed motor control modules, system complexity, maintenance difficulties and uncoordinated control response in existing air conditioning systems.

[0048] Example 2

[0049] This embodiment provides an electrical device, including a motor, and also includes the detection circuit described in the above embodiment.

[0050] In some embodiments of this utility model, the aforementioned electrical equipment is an air conditioner.

[0051] The circuit embodiments described above are merely illustrative. The modules described as separate components may or may not be physically separate. Components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A detection circuit, characterized in that, The detection circuit is configured to correspond one-to-one with the phase lines of the AC power supply, and the detection circuit includes: A voltage divider module includes at least one voltage divider resistor whose input terminal is connected to the corresponding phase line of the AC power supply; An optocoupler, wherein the first terminal of its input side is connected to the output terminal of the voltage divider module, the second terminal of its input side is connected to the neutral wire, the first terminal of its output side is connected to the voltage source through a sensing resistor, the second terminal of its output side is grounded, and a first capacitor is provided between the first terminal and the second terminal of the output side of the optocoupler. The controller MCU is connected between the detection resistor and the first terminal of the output side of the optocoupler. It is used to determine the turn-on and turn-off times of the optocoupler based on the voltage value output between the detection resistor and the first terminal of the output side of the optocoupler, and then predict the zero-crossing point based on the turn-on time, the turn-off time and the symmetry of the voltage waveform input to the optocoupler.

2. The detection circuit according to claim 1, characterized in that, The detection circuit further includes: A protection resistor is disposed between the first terminal and the second terminal on the input side of the optocoupler.

3. The detection circuit according to claim 1, characterized in that, The detection circuit further includes: The second capacitor is disposed between the first terminal on the output side and the second terminal on the input side of the optocoupler.

4. The detection circuit according to claim 3, characterized in that, The detection circuit further includes: The first diode has its anode connected to the second terminal on the input side of the optocoupler, and its cathode connected to the first terminal on the input side of the optocoupler.

5. The detection circuit according to claim 1, characterized in that, The detection circuit further includes: The second diode is disposed between the input terminal of the voltage divider module and the corresponding phase line of the AC power supply.

6. An electrical appliance, comprising a motor, characterized in that, It also includes the detection circuit according to any one of claims 1 to 5.

7. The electrical equipment according to claim 6, characterized in that, The electrical equipment mentioned is an air conditioner.

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