Electromagnetic interference suppression circuit, power supply and electric energy meter
By setting capacitive impedance parts in parallel at both ends of the switching power supply of the flyback switching power supply and adjusting the resonant frequency, the problem of electromagnetic interference and noise signals generated by the flyback switching power supply in high-frequency operation is solved, and effective noise signal suppression and electromagnetic compatibility are achieved.
Patent Information
- Application Number
- CN202421302046.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-07
- Publication Date
- 2025-05-27
- Estimated Expiration
- 2034-06-07
AI Technical Summary
Flyback switching power supply is prone to electromagnetic interference and noise signals during high-frequency operation, resulting in the generation of noise signals of other frequencies other than the effective operating frequency, affecting electromagnetic compatibility.
Capacitive impedance parts are arranged in parallel at both ends of the switching power supply component to form a loop to adjust the resonant frequency. Through the connection between the bypass capacitor C1 and the switching power supply component and the converter, the resonant frequency f0 is adjusted to avoid noise signals of other frequencies except the operating frequency.
It effectively suppresses noise signals at other frequencies other than the effective operating frequency, improves electromagnetic interference problems, and improves electromagnetic compatibility.
Smart Images
Figure CN222915895U_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the technical field of electronic circuits, and particularly relates to an electromagnetic interference suppression circuit, a power supply, and an electric energy meter. Background Art
[0002] With the continuous expansion of the functions of smart meters, the demand for their own load-carrying capacity is also increasing. Switching power supplies are also widely used in smart meters. In related technologies, a flyback switching power supply design topology is usually adopted for the power supply to convert the DC voltage into the required AC voltage and supply power to the load.
[0003] However, the switching working frequency of the switching power supply is relatively high, usually in the range of 65KHz to 130KHz or even higher. And this topology usually has an energy converter, which is very likely to resonate with other electrical components, generating noise signals of other frequencies in addition to the effective working frequency. Moreover, the higher-frequency switching power supply will also bring certain electromagnetic interference. Therefore, how to suppress the above electromagnetic interference and avoid generating noise signals of other frequencies outside the effective working frequency is an urgent problem to be solved. Summary of the Utility Model
[0004] This application provides an electromagnetic interference suppression circuit, a power supply, and an electric energy meter to solve the problem of how to suppress electromagnetic interference and avoid generating noise signals of other frequencies outside the effective working frequency.
[0005] To solve the above technical problems, in a first aspect, this application provides an electromagnetic interference suppression circuit, including a converter and a switching power supply component;
[0006] The first primary winding of the converter is connected to a voltage source. A capacitive impedance component is connected in parallel at both ends of the switching power supply component. One end of the capacitive impedance component is connected to the switching power supply component and then connected to the first primary winding. The other end of the capacitive impedance component is connected to the switching power supply component and then grounded;
[0007] The converter is further provided with a secondary winding assembly, and the secondary winding assembly is connected to a load assembly.
[0008] As a further improvement of this application, the capacitive impedance component is a bypass capacitor, and the bypass capacitor is used to adjust the resonance frequency f0 formed between the switching power supply component and the converter. The calculation formula of the resonance frequency f0 is:
[0009]
[0010] C = C1 + C0
[0011] Among them, L is the inductance value of the first primary winding, C1 is the capacitance value of the bypass capacitor, C0 is the parasitic capacitance value of the switching power supply component, and C is the sum value of C1 + C0.
[0012] As a further improvement of the present application, the secondary winding assembly includes a first secondary winding and a second secondary winding, and the first secondary winding and the second secondary winding are connected to the load assembly.
[0013] As a further improvement of the present application, the converter further includes a second primary winding, and the second primary winding is connected to the load assembly.
[0014] As a further improvement of the present application, the load assembly includes a first load, a second load, and a third load;
[0015] The first secondary winding is connected to the first load, the second secondary winding is connected to the second load, and the second primary winding is connected to the third load.
[0016] As a further improvement of the present application, the switching power supply component is a switching chip, and the switching chip is used to periodically turn on and off to periodically transfer energy to the converter.
[0017] As a further improvement of the present application, when the switching power supply component is turned on, energy is transferred to the converter;
[0018] When the switching power supply component is turned off, the converter transfers the stored energy to the load assembly through the first primary winding, the first secondary winding, and the second secondary winding.
[0019] As a further improvement of the present application, the voltage source is a DC voltage source.
[0020] In a second aspect, the present application provides a power supply, and the power supply includes the electromagnetic interference suppression circuit described in any one of the above.
[0021] In a third aspect, the present application provides an electric energy meter, and the above power supply is provided in the electric energy meter, and the power supply is used to supply power to the electric energy meter.
[0022] Compared with the prior art, the electromagnetic interference suppression circuit, the power supply, and the electric energy meter provided by the embodiments of the present application are applicable to most flyback switching power supplies. By parallelly arranging a capacitive impedance component at both ends of the switching power supply component to form a loop between the DC voltage source, the converter, the switching power supply, and the reference ground, and by adjusting the capacitance value of the capacitive impedance component to further adjust the resonance frequency, other frequency noise signals are avoided except for the operating frequency, effectively improving the electromagnetic interference problem. Description of the Drawings
[0023] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0024] Figure 1 It is a schematic structural diagram of the electromagnetic interference suppression circuit provided by the embodiment of the present application;
[0025] Figure 2 It is a topological structure diagram of a flyback power supply system provided in the related art;
[0026] Figure 3 For Figure 2 The periodic working waveform diagram generated by the switching power supply in the related art shown;
[0027] Figure 4 For Figure 2 The EMI conduction test diagram of the related art shown;
[0028] Figure 5 For Figure 1 The EMI conduction test diagram of the electromagnetic interference suppression circuit described; Specific embodiments
[0029] In order to make the purpose, technical solutions and advantages of the present application more clear and understandable, the following will further describe the present application in detail with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.
[0030] In the description of the present application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined. In the embodiments of the present application, all directional indications (such as up, down, left, right, front, back...) are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion.
[0031] To make the description of the present disclosure more detailed and complete, the following presents an illustrative description of the embodiments and specific examples of the present application; but this is not the only form for implementing or applying the specific examples of the present application. The embodiments cover the features of multiple specific examples and the method steps and their sequences for constructing and operating these specific examples. However, other specific examples can also be used to achieve the same or equivalent functions and step sequences.
[0032] Please refer to Figures 1-5 , which can solve the problem of how to improve the safety and stability of the charging terminal and avoid the influence of lightning on each component inside the charging terminal. The embodiments of the present application provide an electromagnetic interference suppression circuit, a power supply, and a watt-hour meter.
[0033] Please refer to Figure 1 , which is a schematic structural diagram of the electromagnetic interference suppression circuit provided by the embodiments of the present application. The electromagnetic interference suppression circuit includes a converter and a switching power supply component; among them, the converter is provided with a first primary winding and a secondary winding assembly. In the present application, the first primary winding is connected to the voltage source VDC, and a capacitive impedance component is connected in parallel at both ends of the switching power supply component. It can be observed that one end of the capacitive impedance component is connected to the switching power supply component and then connected to the first primary winding, and the other end of the capacitive impedance component is connected to the switching power supply component and then grounded. At the same time, the secondary winding assembly is connected to a load component.
[0034] Please refer to Figure 2 , which is a topological structure diagram of a flyback power supply system provided in the related art. It can be observed that the topological structure of the flyback power supply system provided in the related art includes a power rectification module, an interference noise suppression filter module, a PWM high-frequency switching module, an energy converter module, and a load power consumption module. Specifically, the output end of the power rectification module is respectively connected to the input end of the filter module, the output end of the filter module is connected to the input end of the PWM high-frequency switching module, and the output end of the PWM high-frequency switching module is connected to the electrical load through an energy converter.
[0035] However, in the related art, the power rectification module uses high-voltage direct rectification to convert alternating current into direct current voltage. The alternating current is the domestic standard 220V sinusoidal alternating current with a frequency of 50Hz. The energy converter module also mainly uses inductive components as the key components for energy storage and transfer. During the working cycle, it is extremely easy to resonate with other capacitive components and generate noise signals with frequencies other than the effective working frequency. Eventually, it will generate noise that is not conducive to the EMI (Electromagnetic Interference) evaluation index, such as Figure 3 the noise source shown in
[0036] Please refer to Figure 3 , which is Figure 2 the periodic working waveform diagram generated by the switching power supply in the related art shown in
[0037] Please refer to Figure 4 , which is Figure 2The EMI conduction test diagram of the related art shown, according to Figure 4 From the generated energy distribution, it is obvious that the energy value in the marked area is higher than the maximum value of the noise limit of electronic products. The corresponding frequency point is in the area around 530KHz, and further analysis can also show that there are abnormal index in its harmonic frequency bands. Further explanation is that when the switching power supply works periodically, in addition to its own working frequency, it still generates main vibration points in other high-energy frequency bands, and the duty cycle is relatively high within the period, which Figure 3 coincides with the noise source shown in
[0038] Therefore, it is necessary to effectively suppress the noise signal generated during the process. Figure 1 Please continue to refer to
[0039] Specifically, the resonant frequency f0 can be adjusted by the formula and C = C1 + C0. Here, L is the inductance value of the first primary winding in the converter, C1 is the capacitance value of the bypass capacitor, C0 is the parasitic capacitance value of the switching power supply component, and C is the sum value of C1 + C0. Since the bypass capacitor C1 is connected in parallel at both ends of the switching power supply component in this application, the value of C in the formula can be adjusted, so as to further adjust the resonant frequency f0.
[0040] As an optional implementation manner, the switching power supply component provided in this application needs to be periodically turned on and off, and is turned on and off at a certain frequency to transfer the energy within the period to the converter, and then the converter transfers the stored energy to the load component. Since the converter will generate a resonant signal with a certain frequency while storing and releasing energy, which is converted into noise, corresponding to the Figure 3 noise source shown in
[0041] In this application, by connecting the bypass capacitor C1 in parallel at both ends of the switching power supply component, the resonant frequency f0 can be effectively adjusted, thereby suppressing the EMI (Electromagnetic Interference) noise signal generated during the process of the converter storing and releasing energy.
[0042] Preferably, the above voltage source VDC can be set in the form of a DC voltage source.
[0043] As an alternative embodiment, it can be observed that the above-mentioned secondary side winding assembly includes a first secondary side winding and a second secondary side winding. The first secondary side winding and the second secondary side winding are connected to the load assembly, so as to transfer energy to the load assembly for use. The converter is further provided with a second primary side winding, and the second primary side winding is also connected to a corresponding load assembly.
[0044] In the embodiment of the present application, the above-mentioned load assembly includes a first load, a second load, and a third load. In the present application, the first secondary side winding is connected to the first load, the second secondary side winding is connected to the second load, and the second primary side winding is connected to the third load.
[0045] Since the switching power supply component periodically turns on and off, when the switching power supply component is turned on, it can transfer energy to the converter. When the switching power supply component is turned off, the converter transfers the stored energy to the load assembly through the above-mentioned first primary side winding, first secondary side winding, and second secondary side winding; specifically, the first secondary side winding transfers energy to the first load, the second secondary side winding transfers energy to the second load, and the second primary side winding transfers energy to the third load.
[0046] It should be noted that the above-provided converter structure is only an example of an alternative converter embodiment. Other types of converters are also feasible, as long as the bypass capacitor C1 can be determined according to the inductance value L of the inductive element in the actual converter and the parasitic capacitance value C0 of the switching power supply component to further adjust the resonant frequency f0. The present application does not further limit the specific structure of the converter and the specific winding method of each winding in the converter, nor should it be regarded as any limitation to the present application.
[0047] Please refer to Figure 5 For Figure 1 the EMI conduction test diagram of the electromagnetic interference suppression circuit, it can be observed that after the bypass capacitor C1 is connected in parallel at both ends of the switching power supply component, the energy values in each frequency band are significantly attenuated, and the energy distribution of the noise curve is below the specified energy average value and peak line, which significantly suppresses the noise signal.
[0048] It can be understood that since different converters have different inductive elements, the values of the parasitic capacitances in different switching power supply components are also different, and the formed resonant frequency points are also different. Therefore, in practical applications, the bypass capacitor C1 needs to be adjusted accordingly according to the converter, the switching power supply component, and the specific circuit requirements. Therefore, the present application does not further limit the specific capacitance value of the bypass capacitor C1 and the specific number of the bypass capacitor C1 set, and those skilled in the art should know this.
[0049] Based on the above electromagnetic interference suppression circuit, the present application further provides a power supply and an electricity meter including the power supply. The power supply powers the electricity meter to make the EMI of the electricity meter reach a specified reasonable range and meet the low-power consumption requirements. The specific implementation method can refer to the description in the electromagnetic interference suppression circuit provided in the above application embodiment and will not be elaborated here.
[0050] The electromagnetic interference suppression circuit, power supply and electricity meter provided in the embodiments of the present application are applicable to most flyback switching power supplies. By parallelly arranging a capacitive impedance component at both ends of the switching power supply component, a loop is formed between the DC voltage source, the converter, the switching power supply and the reference ground. By adjusting the capacitance value of the capacitive impedance component, the resonant frequency is further adjusted to avoid generating noise signals of other frequencies except the working frequency, effectively improving the electromagnetic interference problem.
[0051] It can be understood that the technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.
[0052] The above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present application. However, the present application is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present application, and these modifications and improvements are also regarded as the protection scope of the present application.
Claims
1. An electromagnetic interference suppression circuit, characterized in that: Including converter and switching power supply; The first primary winding of the converter is connected to a voltage source, and capacitive impedance components are arranged in parallel at both ends of the switching power supply component, one end of the capacitive impedance component is connected to the switching power supply component and then connected to the first primary winding, and the other end of the capacitive impedance component is connected to the switching power supply component and then grounded; The converter is also provided with a secondary winding component, and the secondary winding component is connected to a load component.
2. The electromagnetic interference suppression circuit according to claim 1, characterized in that: The capacitive impedance component is a bypass capacitor, and the bypass capacitor is used to adjust the resonant frequency f0 formed between the switching power supply component and the converter. The calculation formula of the resonant frequency f0 is: C=C1+C0 Wherein, L is the inductance value of the first primary winding, C1 is the capacitance value of the bypass capacitor, C0 is the parasitic capacitance value of the switching power supply, and C is the sum of C1+C0.
3. The electromagnetic interference suppression circuit according to claim 1, characterized in that: The secondary winding assembly includes a first secondary winding and a second secondary winding, and the first secondary winding and the second secondary winding are connected to the load assembly.
4. The electromagnetic interference suppression circuit according to claim 3, characterized in that: The converter further includes a second primary winding connected to the load component.
5. The electromagnetic interference suppression circuit according to claim 4, characterized in that: The load assembly includes a first load, a second load and a third load; The first secondary winding is connected to the first load, the second secondary winding is connected to the second load, and the second primary winding is connected to the third load.
6. The electromagnetic interference suppression circuit according to claim 4, characterized in that: The switching power supply is a switch chip, which is used to be switched on and off periodically to transfer energy to the converter periodically.
7. The electromagnetic interference suppression circuit according to claim 6, characterized in that: When the switching power supply is turned on, energy is transferred to the converter; When the switching power supply is disconnected, the converter transfers the stored energy to the load component through the first primary winding, the first secondary winding and the second secondary winding.
8. The electromagnetic interference suppression circuit according to claim 1, characterized in that: The voltage source is a DC voltage source.
9. A power supply, characterized in that: The power supply comprises the electromagnetic interference suppression circuit according to any one of claims 1-8.
10. An electric energy meter, characterized in that: The electric energy meter is provided with the power supply as claimed in claim 9, and the power supply is used to supply power to the electric energy meter.