A bridgeless PFC zero-crossing detection device
By combining signal sampling, processing, and detection modules, the problem of low signal quality in bridgeless PFC zero-crossing detection devices is solved, achieving high-precision and stable zero-crossing detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- WAUKEYUANXIN (NANJING) ELECTRONIC TECHNOLOGY CO LTD
- Filing Date
- 2025-05-20
- Publication Date
- 2026-06-30
Smart Images
Figure CN224436435U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of electronic circuit technology, specifically relating to a bridgeless PFC zero-crossing detection device. Background Technology
[0002] In the field of power electronics, PFC (bridgeless power factor correction) circuits are widely used in various power systems due to their advantages such as high efficiency and energy saving. During the operation of bridgeless PFC circuits, accurately detecting the zero-crossing point of AC signals is the key to achieving power factor correction. However, some traditional zero-crossing detection devices use simple analog circuits, which often lack effective filtering and shaping measures, resulting in low signal quality input to the zero-crossing detection stage, mixed with a lot of interference and noise, leading to low detection accuracy and unstable zero-crossing signal output. Utility Model Content
[0003] In view of the above-mentioned shortcomings in the prior art, the present invention provides a bridgeless PFC zero-crossing detection device to solve the problems in the background art.
[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0005] A bridgeless PFC zero-crossing detection device includes a signal sampling module for acquiring AC voltage and current signals in a bridgeless PFC circuit; a signal processing module, the output of which is connected to the input of which, amplifying, filtering, and shaping the acquired signals; a zero-crossing detection module, the output of which is connected to the input of which, including a comparator, configured to compare the processed signal with a zero level to detect the zero-crossing point of the AC signal; and an output module, the output of which is connected to the input of which, shaping and buffering the zero-crossing pulse signal output by the zero-crossing detection module to meet the interface requirements of subsequent circuits before finally outputting it to the subsequent circuits.
[0006] Preferably, the signal sampling module includes a voltage sampling unit employing a resistor divider network and a current sampling unit utilizing a Hall current sensor.
[0007] Preferably, the signal processing module includes an amplifier circuit, a second-order active bandpass filter, and a Schmitt trigger. The amplifier circuit uses an operational amplifier, and the amplification factor is adjusted by setting a gain resistor to amplify the weak signal output by the signal sampling module to an amplitude range suitable for subsequent processing. The second-order active bandpass filter is used to filter out high-frequency noise and low-frequency interference in the amplified signal. The Schmitt trigger is used to shape the filtered signal and convert it into a standard square wave signal.
[0008] Preferably, the zero-crossing detection module further includes a filtering and protection circuit, which is used to filter out interference signals and protect the comparator from damage caused by excessive voltage.
[0009] Preferably, the output module includes a level conversion circuit and a buffer. The level conversion circuit inputs the zero-crossing pulse signal output by the zero-crossing detection module to the input terminal of the level conversion chip, and the level conversion chip converts the signal level to a level compatible with subsequent circuits. The buffer is used to enhance the signal driving capability.
[0010] Compared with the prior art, this utility model has the following advantages: through the amplification, filtering, and shaping operations in the signal processing module, and the filtering and protection measures in the zero-crossing detection module, the entire device constructs a complete anti-interference system, which has a strong resistance to various electromagnetic interferences, voltage fluctuations and other external factors, ensuring the stability and reliability of the zero-crossing detection function during long-term operation, reducing the occurrence of misjudgments, and greatly improving the accuracy of zero-crossing detection. Attached Figure Description
[0011] Figure 1 This is a block diagram of a bridgeless PFC zero-crossing detection device according to the present invention;
[0012] Figure 2 This is a block diagram of the signal processing module in a bridgeless PFC zero-crossing detection device of this utility model;
[0013] Figure 3 This is a block diagram of the zero-crossing detection module in a bridgeless PFC zero-crossing detection device of this utility model;
[0014] Figure 4 This is a block diagram of the output module in a bridgeless PFC zero-crossing detection device of this utility model. Detailed Implementation
[0015] To enable those skilled in the art to better understand this utility model, the technical solution of this utility model will be further described below in conjunction with the accompanying drawings and embodiments.
[0016] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this patent. To better illustrate the embodiments of this utility model, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.
[0017] In the accompanying drawings of this utility model, the same or similar reference numerals correspond to the same or similar components. In the description of this utility model, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.
[0018] In the description of this utility model, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating the connection relationship between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0019] Example 1:
[0020] like Figure 1-4 As shown, this utility model provides a bridgeless PFC zero-crossing detection device, comprising: a signal sampling module for acquiring AC voltage and current signals in a bridgeless PFC circuit; a signal processing module, the output of which is connected to the input of which, and used to amplify, filter, and shape the acquired signals; a zero-crossing detection module, the output of which is connected to the input of which, and includes a comparator configured to compare the signal processed by the signal processing module with a zero level, using a high-precision LM393 comparator chip to detect the zero-crossing point of the AC signal; and an output module, the output of which is connected to the input of which, and used to shape and buffer the zero-crossing pulse signal output by the zero-crossing detection module to meet the interface requirements of subsequent circuits before finally outputting it to the subsequent circuits.
[0021] The signal sampling module includes a voltage sampling unit using a resistor divider network and a current sampling unit using a Hall current sensor. When acquiring signals for a common bridgeless PFC circuit with an input AC voltage of 220V, a resistor divider network consisting of two high-precision, low-temperature drift metal film resistors with resistance values of 1MΩ and 100kΩ is selected as the voltage sampling unit. Considering that the maximum expected current of the inductor in the bridgeless PFC circuit is 5A, a Hall current sensor with a range of 10A is selected.
[0022] The signal processing module includes an amplifier circuit, a second-order active bandpass filter, and a Schmitt trigger. The amplifier circuit uses an LM358 operational amplifier, and the amplification factor is adjusted by setting the gain resistor to amplify the weak signal output from the signal sampling module to a suitable amplitude range for subsequent processing. The center frequency of the second-order active bandpass filter is set to 50Hz, and the bandwidth is 20Hz-80Hz. It is used to filter out high-frequency noise and low-frequency interference in the amplified signal. The Schmitt trigger uses a 74HC14 Schmitt trigger chip, and the threshold voltage of the Schmitt trigger is set to 2V. It is used to shape the filtered signal and convert it into a standard square wave signal with clear and stable level changes.
[0023] In the zero-crossing detection module, after the square wave signal is connected to the LM393 comparator, when the level of the square wave signal changes from above zero to below zero, or from below zero to above zero, the output level of the comparator will flip accordingly, thereby generating an accurate zero-crossing pulse signal.
[0024] Furthermore, the zero-crossing detection module also includes filtering and protection circuits. An RC filter circuit consisting of a 0.01μF ceramic capacitor and a 1kΩ resistor is connected to the input of the comparator. This filter circuit can further filter out tiny high-frequency interference signals that may remain in the input signal, preventing these interferences from affecting the accurate judgment of the comparator. 1N4148 diodes are connected to the input and output of the comparator respectively to limit the amplitude of the input and output signals within the safe operating voltage range of the comparator from -0.7V to +5.7V, thereby protecting the comparator from damage by excessive voltage and ensuring that the zero-crossing detection module can stably and reliably output zero-crossing pulse signals.
[0025] The output module includes a level conversion circuit and a buffer. The level conversion circuit inputs the zero-crossing pulse signal output by the zero-crossing detection module to the input terminal of the level conversion chip. The level conversion chip converts the signal level to a level compatible with subsequent circuits. The buffer uses a 74LVC245 buffer chip to enhance the signal driving capability.
[0026] The above are merely embodiments of this utility model. The circuits, electronic components, and modules involved are all prior art, fully achievable by those skilled in the art, and require no further explanation. The content protected by this application does not involve improvements to the software and methods. Commonly known structures and characteristics in the solution are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field to which this utility model pertains prior to the application date or priority date, are able to access all prior art in that field, and possess the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of this utility model. These should also be considered within the scope of protection of this utility model, and will not affect the effectiveness of the implementation of this utility model or the practicality of the patent.
Claims
1. A bridgeless PFC zero-crossing detection device, characterized by: Includes a signal sampling module, which is used to acquire AC voltage and current signals in a bridgeless PFC circuit; The signal processing module is connected to the input of the signal sampling module. The signal processing module is used to amplify, filter, and shape the acquired signal. A zero-crossing detection module is provided, wherein the output terminal of the signal processing module is connected to the input terminal of the zero-crossing detection module, the zero-crossing detection module includes a comparator, and the zero-crossing detection module is configured to compare the signal processed by the signal processing module with a zero level to detect the zero-crossing point of the AC signal. The output module is connected to the input of the zero-crossing detection module. The output module is used to shape and buffer the zero-crossing pulse signal output by the zero-crossing judgment module to meet the interface requirements of the subsequent circuits and finally output it to the subsequent circuits.
2. The bridgeless PFC zero-crossing detection device as described in claim 1, characterized in that: The signal sampling module includes a voltage sampling unit employing a resistor divider network and a current sampling unit utilizing a Hall current sensor.
3. The bridgeless PFC zero-crossing detection device as described in claim 2, characterized in that: The signal processing module includes an amplifier circuit, a second-order active bandpass filter, and a Schmitt trigger. The amplifier circuit uses an operational amplifier, and the amplification factor is adjusted by setting the gain resistor to amplify the weak signal output by the signal sampling module to a suitable amplitude range for subsequent processing. The second-order active bandpass filter is used to filter out high-frequency noise and low-frequency interference in the amplified signal. The Schmitt trigger is used to shape the filtered signal and convert it into a standard square wave signal.
4. The bridgeless PFC zero-crossing detection device as described in claim 3, characterized in that: The zero-crossing detection module also includes filtering and protection circuitry, which is used to filter out interference signals and protect the comparator from damage caused by excessive voltage.
5. The bridgeless PFC zero-crossing detection device as described in claim 4, characterized in that: The output module includes a level conversion circuit and a buffer. The level conversion circuit inputs the zero-crossing pulse signal output by the zero-crossing detection module to the input terminal of the level conversion chip, and the level conversion chip converts the signal level to a level compatible with subsequent circuits. The buffer is used to enhance the signal driving capability.