Circuit for eliminating electromagnetic interference and method for controlling the same

Abstract

The application discloses a circuit for eliminating electromagnetic interference and a control method thereof. The circuit for eliminating electromagnetic interference comprises a circuit to be eliminated, a control module and an electromagnetic interference elimination circuit. The control module is connected with the circuit to be eliminated, used for detecting a driving voltage of the circuit to be eliminated, and turned on and turned off according to the size of the driving voltage and a preset threshold voltage. The electromagnetic interference elimination circuit is connected with the control module and the circuit to be eliminated respectively, used for storing and releasing a target electromagnetic interference signal in the circuit to be eliminated according to the turning on and turning off of the control module. When the control module is turned on, the electromagnetic interference elimination circuit stores the target electromagnetic interference signal; when the control module is turned off, the electromagnetic interference elimination circuit discharges to complete the elimination of the target electromagnetic interference signal. The application can eliminate the specified electromagnetic interference, thereby realizing the elimination of high-frequency broadband electromagnetic interference, and reducing the electromagnetic emission of the equipment to the environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of eliminating electromagnetic interference, and particularly relates to a circuit for eliminating electromagnetic interference and a control method thereof. BACKGROUND

[0002] The conventional multi-stage filter circuit generally utilizes the band-stop characteristic of inductance and LC series resonance bypass interference to eliminate high-frequency electromagnetic interference, but the frequency band is relatively limited, and the loss of electromagnetic interference signal is low, resulting in an unsatisfactory elimination effect. In addition, once high-frequency wide-band electromagnetic interference is encountered, the parasitic capacitance effect of the choke coil in the conventional filter circuit will cause the filter to fail, and the high-frequency wide-band electromagnetic interference cannot be eliminated, so that the device using the multi-stage filter circuit will emit a large amount of electromagnetic interference signal, thereby affecting other devices in the environment. SUMMARY

[0003] The present application provides a circuit for eliminating electromagnetic interference and a control method thereof, which can eliminate electromagnetic interference of a specified frequency band, thereby eliminating high-frequency wide-band electromagnetic interference signals and reducing electromagnetic emission of the device to the environment.

[0004] In a first aspect, the present application provides a circuit for eliminating electromagnetic interference, which comprises a circuit to be eliminated, a control module and an electromagnetic interference elimination circuit. The control module is connected to the circuit to be eliminated, and is used to detect the driving voltage of the circuit to be eliminated, and to turn on and turn off according to the size of the driving voltage and the preset threshold voltage. The electromagnetic interference elimination circuit is connected to the control module and the circuit to be eliminated, and is used to store and release the target electromagnetic interference signal in the circuit to be eliminated according to the turn-on and turn-off of the control module. When the control module is turned on, the electromagnetic interference elimination circuit stores the target electromagnetic interference signal, and when the control module is turned off, the electromagnetic interference elimination circuit discharges to complete the elimination of the target electromagnetic interference signal.

[0005] Further, the electromagnetic interference elimination circuit comprises a tuning capacitor and an energy storage coil. One end of the tuning capacitor is connected to the circuit to be eliminated, and is used to receive the target electromagnetic interference signal. The other end of the tuning capacitor is connected to the energy storage coil through the control module. When the control module is turned on, the energy storage loop formed by the tuning capacitor and the energy storage coil stores the target electromagnetic interference signal. When the control module is turned off, the energy storage coil releases the target electromagnetic interference signal.

[0006] Further, the electromagnetic interference elimination circuit further comprises a first diode and a load; a positive electrode of the first diode is connected with one end of the load, a negative electrode of the first diode is connected with one end of the energy storage coil, and the other end of the load is connected with the other end of the energy storage coil.

[0007] Further, the electromagnetic interference elimination circuit further comprises a second diode, a positive electrode of the second diode is connected with the energy storage coil, and a negative electrode of the second diode is connected with the metal shell.

[0008] Further, the load is a cement resistor.

[0009] Further, the circuit to be eliminated is a power factor correction circuit.

[0010] Further, the power factor correction circuit comprises a PFC inductor, a switch tube and a third diode; the PFC inductor is connected with a drain of the switch tube and the third diode respectively, a gate of the switch tube is connected with the control module, and a source of the switch tube is connected with the tuning capacitor.

[0011] Further, the tuning capacitor is a thin film capacitor.

[0012] Further, the energy storage coil comprises a plurality of coils connected in series.

[0013] In a second aspect, the present application further provides a control method, the control method comprising:

[0014] acquiring a driving voltage of a circuit to be eliminated, and determining whether the driving voltage is less than a preset voltage threshold;

[0015] if the driving voltage is less than the preset voltage threshold, controlling to turn on itself to make the electromagnetic interference elimination circuit absorb a target electromagnetic interference signal;

[0016] if the driving voltage is not less than the preset voltage threshold, controlling to turn off itself to make the electromagnetic interference elimination circuit discharge.

[0017] The circuit for eliminating electromagnetic interference and the control method thereof can detect the driving voltage of the circuit to be eliminated by the control module, and control the conduction and turn-off of the control module according to the size of the driving voltage and the preset voltage threshold. Meanwhile, the electromagnetic interference elimination circuit can switch between energy storage and discharge according to the conduction and turn-off of the control module. When the control module is turned on, the electromagnetic interference elimination circuit stores the target electromagnetic interference signal to absorb the target electromagnetic interference signal in the circuit to be eliminated. When the control module is turned off, the electromagnetic interference elimination circuit discharges to eliminate the target electromagnetic interference signal. The target electromagnetic interference signal is determined by the electromagnetic interference elimination circuit, so that not only the ordinary electromagnetic interference signal can be eliminated, but also the high-frequency broadband electromagnetic interference signal can be eliminated, and the electromagnetic emission of the equipment to the environment is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the present application, the drawings needed in the following embodiment description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0019] Figure 1 The block diagram of the circuit for eliminating electromagnetic interference provided by an embodiment of the present application is shown in the figure.

[0020] Figure 2 The circuit diagram of the circuit for eliminating electromagnetic interference provided by an embodiment of the present application is shown in the figure.

[0021] Figure 3 The circuit diagram of the circuit for eliminating electromagnetic interference provided by an embodiment of the present application is shown in the figure.

[0022] Figure 4 The flowchart of the control method provided by an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0023] The technical solutions in the present application will be described in detail below with reference to the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0024] It should be understood that when used in the specification and the appended claims, the terms "comprise" and "include" indicate the presence of described features, integers, steps, operations, elements, and / or components, but do not exclude one or more other features, integers, steps, operations, elements, components, and / or sets thereof.

[0025] It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in this specification and the appended claims, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0026] Referring to Figures 1 to 3 , Figure 1 a block schematic diagram of an electromagnetic interference elimination circuit 100 provided by an embodiment of the present application is provided; Figure 2 a circuit diagram of an electromagnetic interference elimination circuit 100 provided by an embodiment of the present application is provided;

[0027] Figure 3 a circuit schematic diagram of an electromagnetic interference elimination circuit 100 provided by an embodiment of the present application is provided. As shown in Figure 1 the electromagnetic interference elimination circuit 100 provided by the present application includes a to-be-eliminated circuit 10, a control module 20 and an electromagnetic interference elimination circuit 30; the control module 20 is connected with the to-be-eliminated circuit 10, used for detecting a driving voltage of the to-be-eliminated circuit 10, and turning on and turning off according to the size of the driving voltage and a preset threshold voltage; the electromagnetic interference elimination circuit 30 is connected with the control module 20 and the to-be-eliminated circuit 10 respectively, used for storing and releasing a target electromagnetic interference signal in the to-be-eliminated circuit 10 according to the turning on and turning off of the control module 20; when the control module 20 is turned on, the electromagnetic interference elimination circuit 30 stores the target electromagnetic interference signal, and when the control module 20 is turned off, the electromagnetic interference elimination circuit 30 discharges to complete the elimination of the target electromagnetic interference signal, thereby reducing the electromagnetic emission of a device with the electromagnetic interference elimination circuit 100 provided by the present application.

[0028] Specifically, the circuit to be eliminated 10 is a circuit that needs to be eliminated electromagnetic interference, which can be a circuit involving active device switching, for example, a power factor correction circuit, a DC-DC circuit. The input end of the circuit to be eliminated 10 is connected with the front-end circuit 200, and the output end is connected with the rear-end circuit 300. The control module 20 can be a control chip, one pin of which is connected with the circuit to be eliminated 10 for detecting the driving voltage of the circuit to be eliminated 10, and controlling the conduction and turn-off of itself according to the size of the driving voltage and the preset voltage threshold, for example, when the detected driving voltage is less than the preset voltage threshold, the control module 20 is turned on, and when the detected driving voltage is greater than or equal to the preset voltage threshold, the control module 20 is turned off. The electromagnetic interference elimination circuit 30 is connected with the circuit to be eliminated 10 for receiving the target electromagnetic interference signal of the circuit to be eliminated 10, which is determined by the electromagnetic interference elimination circuit 30 itself, for example, the electromagnetic interference signal of a certain high frequency band can be eliminated, that is, when the electromagnetic interference signal of a high frequency wide frequency band needs to be eliminated, only the parameters of the electromagnetic interference elimination circuit 30 need to be set, so as to realize the elimination of the electromagnetic interference signal of the high frequency wide frequency. The electromagnetic interference elimination circuit 30 is also connected with the control module 20 for storing energy and discharging the target electromagnetic interference signal in the circuit to be eliminated 10 according to the conduction and turn-off of the control module 20. For example, when the control module 20 is turned on, the electromagnetic interference elimination circuit 30 absorbs the target electromagnetic interference signal in the circuit to be eliminated 10 to store energy, and when the control module 20 is turned off, the electromagnetic interference elimination circuit 30 releases the stored energy, thereby completing the elimination of the target electromagnetic interference signal. Through the periodic conduction and turn-off of the control module 20, the electromagnetic interference elimination circuit 30 is switched between energy storage and discharge, and the elimination of the target electromagnetic interference signal is completed.

[0029] As shown in Figure 2 As a further embodiment, the electromagnetic interference elimination circuit 30 includes a tuning capacitor C1 and an energy storage coil L1, one end of the tuning capacitor C1 is connected with the circuit to be eliminated 10 for receiving the target electromagnetic interference signal, and the other end is connected with the energy storage coil L1 through the control module 20; wherein when the control module 20 is turned on, the energy storage loop formed by the tuning capacitor C1 and the energy storage coil L1 stores the target electromagnetic interference signal, and when the control module 20 is turned off, the energy storage coil L1 releases the target electromagnetic interference signal.

[0030] One end of the tuning capacitor C1 is connected with the circuit to be eliminated 10 for receiving the target electromagnetic interference signal, and the other end is connected with the energy storage coil L1 through the control module 20. When the control module 20 is turned on, the tuning capacitor C1 and the energy storage coil L1 form a loop for starting to absorb the target electromagnetic interference signal. When the control module 20 is turned off, the loop between the tuning capacitor C1 and the energy storage coil L1 is interrupted, and the energy storage coil L1 releases the stored energy to complete the elimination of the target electromagnetic interference signal. In addition, when the control module 20 is turned on, the tuning capacitor C1 and the energy storage coil L1 form a resonance circuit. The frequency band of the electromagnetic interference signal to be eliminated can be determined by setting the parameters of the tuning capacitor C1 and the energy storage coil L1, so as to realize the elimination of the high-frequency and wide-frequency electromagnetic interference signal. The energy storage coil L1 can be replaced by an energy storage inductor for energy storage.

[0031] As a further embodiment, the electromagnetic interference elimination circuit 30 further comprises a first diode D1 and a load. The anode of the first diode D1 is connected with one end of the load, and the cathode is connected with one end of the energy storage coil L1. The other end of the load is connected with the other end of the energy storage coil L1.

[0032] The first diode D1 functions as a freewheeling diode, and the load is used for storing the energy released by the energy storage coil L1. The load can be a cement resistor R1, a heat sink, a combination of the cement resistor R1 and the heat sink, and other common loads known to those skilled in the art, which are not limited here.

[0033] As a further embodiment, the electromagnetic interference elimination circuit 30 further comprises a second diode D2. The anode of the second diode D2 is connected with the energy storage coil L1, and the cathode is connected with a metal shell.

[0034] The anode of the second diode D2 is connected with the energy storage coil L1, and the cathode is connected with the metal shell. The second diode D2 mainly functions as an output limiting amplifier to prevent the interference of the output end.

[0035] As a further embodiment, the load is a cement resistor R1.

[0036] The load can be a cement resistor R1, which consumes the energy released by the energy storage coil L1.

[0037] As a further embodiment, the circuit to be eliminated 10 is a power factor correction circuit.

[0038] As a further embodiment, the power factor correction circuit comprises a PFC inductor L2, a switch tube Q1 and a third diode D3; the PFC inductor L2 is connected with the drain of the switch tube Q1 and the third diode D3 respectively, the gate of the switch tube Q1 is connected with the control module 20, and the source of the switch tube Q1 is connected with the tuning capacitor C1.

[0039] When the to-be-eliminated circuit 10 is a power factor correction circuit, the front-stage circuit 200 can be a rectifier circuit and a power supply circuit, and the rear-stage circuit 300 can be an electric device. The power factor correction circuit can comprise a PFC inductor L2, a switch tube Q1 and a third diode D3, the gate of the switch tube Q1 is connected with the control module 20, the source of the switch tube Q1 is connected with the tuning capacitor C1, and the target electromagnetic interference signal of the power factor correction circuit can enter the tuning capacitor C1 through the source. In the stage of conduction of the PFC inductor L2 to the third diode D3, the control module 20 detects the driving voltage of the switch tube Q1, and when the driving voltage is lower than a preset voltage threshold, the control module 20 is turned on, and the tuning capacitor C1 and the energy storage coil L1 absorb the target electromagnetic interference signal to store energy. In the charging stage of the PFC inductor L2, if the control module 20 detects that the driving voltage is greater than or equal to the preset voltage threshold, the control module 20 is turned off, and the energy storage coil L1 is discharged. That is, the on and off periods of the control module 20 are the same as the switching period of the power factor correction circuit, so as to eliminate the target electromagnetic interference signal in the power factor circuit. The switch tube Q1 can be a MOS tube or an IGBT tube, which is not limited here.

[0040] As a further embodiment, the tuning capacitor C1 is a thin-film capacitor.

[0041] The tuning capacitor C1 can be a common ceramic capacitor or a thin-film capacitor. If it is required to eliminate electromagnetic interference of a higher frequency, for example, electromagnetic interference of 1 MHz or above, a copper-clad surface in a geometric pattern can be arranged on the top layer and the bottom layer of the PCB, and the size of the interlayer capacitance of the PCB is designed, so as to replace the conventional capacitor. The geometric pattern includes but is not limited to square, circle and rhombus. As shown in FIG. 4, a square copper-clad surface can be arranged on the PCB to replace the conventional capacitor. When the control module 20 is turned on, the target electromagnetic interference signal enters the tuning capacitor C1 and is stored by the energy storage coil L1. When the control module 20 is turned off, the loop between the tuning capacitor C1 and the energy storage coil L1 is interrupted, and the energy storage coil L1 is discharged. Figure 3

[0042] As a further embodiment, the energy storage coil L1 comprises a plurality of coils connected in series.

[0043] ​When the required inductance of the energy storage coil L1 is low, a ring-shaped honeycomb trace can be arranged on the PCB, and a plurality of coils are connected in series to form the energy storage coil L1, which is used to replace the conventional energy storage inductor. Figure 3 As shown in FIG. 2, the plurality of coils are connected in series and arranged on the PCB in the form of a ring-shaped honeycomb trace. When the control module 20 is turned on, the energy storage coil L1 starts to store energy. When the control module 20 is turned off, the energy storage coil L1 is discharged through the first diode D1, the cement resistor R1 and the heat sink.

[0044] Please refer to Figure 4 , Figure 4 FIG. 1 is a flowchart of a control method provided by an embodiment of the present application. The control method of the embodiment of the present application can be applied to the control module of the electromagnetic interference elimination circuit provided by the embodiment of the present application. As shown in FIG. 1, the control method comprises steps S110-S130. Figure 4

[0045] S110, the driving voltage of the circuit to be eliminated is obtained, and it is judged whether the driving voltage is less than a preset voltage threshold.

[0046] In the embodiment of the present application, the control module detects the driving voltage of the circuit to be eliminated in real time, obtains the driving voltage, compares the driving voltage with the preset voltage threshold, and judges whether the driving voltage is less than the preset voltage threshold.

[0047] S120, if the driving voltage is less than the preset voltage threshold, the control module is turned on to make the electromagnetic interference elimination circuit absorb the target electromagnetic interference signal.

[0048] In the embodiment of the present application, when the driving voltage is less than the preset voltage threshold, the control module is turned on to make the electromagnetic interference elimination circuit absorb the target electromagnetic interference signal.

[0049] S130, if the driving voltage is not less than the preset voltage threshold, the control module is turned off to make the electromagnetic interference elimination circuit discharge.

[0050] In the embodiment of the present application, when the driving voltage is greater than or equal to the preset voltage threshold, the control module is turned off to make the electromagnetic interference elimination circuit discharge, thereby completing the elimination of the target electromagnetic interference signal.

[0051] The present application sets an electromagnetic interference elimination circuit and a control module. The control module is turned on and off according to the size of the driving voltage of the circuit to be eliminated and the preset voltage threshold. The electromagnetic interference elimination circuit realizes energy storage and discharge according to the turning on and off of the control module, thereby realizing the absorption and elimination of the target electromagnetic interference signal in the circuit to be eliminated, and finally realizing the elimination of the electromagnetic interference signal of the conventional frequency band and the high-frequency wide frequency, and improving the filtering performance.​

[0052] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any skilled person in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A circuit for eliminating electromagnetic interference, characterized in that, The application relates to a circuit for eliminating electromagnetic interference, which comprises: a circuit to be eliminated, which is a power factor correction circuit; a control module connected with the circuit to be eliminated, used for detecting the driving voltage of the circuit to be eliminated and turning on and off according to the size of the driving voltage and a preset threshold voltage; an electromagnetic interference eliminating circuit connected with the control module and the circuit to be eliminated respectively, used for storing and releasing a target electromagnetic interference signal in the circuit to be eliminated according to the turning on and off of the control module; when the control module is turned on, the electromagnetic interference eliminating circuit stores the target electromagnetic interference signal, and when the control module is turned off, the electromagnetic interference eliminating circuit discharges to eliminate the target electromagnetic interference signal; the electromagnetic interference eliminating circuit comprises a tuning capacitor and an energy storage coil, one end of the tuning capacitor is connected with the circuit to be eliminated and used for receiving the target electromagnetic interference signal, and the other end of the tuning capacitor is connected with the energy storage coil through the control module; when the control module is turned on, the energy storage loop formed by the tuning capacitor and the energy storage coil stores the target electromagnetic interference signal, and when the control module is turned off, the energy storage coil releases the target electromagnetic interference signal.

2. The electromagnetic interference cancellation circuit of claim 1, wherein, The electromagnetic interference eliminating circuit further comprises a first diode and a load; the anode of the first diode is connected with one end of the load, the cathode of the first diode is connected with one end of the energy storage coil, and the other end of the load is connected with the other end of the energy storage coil.

3. The electromagnetic interference cancellation circuit of claim 2, wherein, The electromagnetic interference eliminating circuit further comprises a second diode, the anode of the second diode is connected with the energy storage coil, and the cathode of the second diode is connected with a metal shell.

4. The electromagnetic interference cancellation circuit of claim 2, wherein, The load is a cement resistor.

5. The electromagnetic interference cancellation circuit of claim 1, wherein, The power factor correction circuit comprises a PFC inductor, a switch tube and a third diode; the PFC inductor is connected with the drain of the switch tube and the third diode respectively, the gate of the switch tube is connected with the control module, and the source of the switch tube is connected with the tuning capacitor.

6. The electromagnetic interference cancellation circuit of claim 1, wherein, The tuning capacitor is a thin film capacitor.

7. The electromagnetic interference cancellation circuit of claim 1, wherein, The energy storage coil comprises a plurality of coils connected in series.

8. A control method characterized by, The method is applied to the control module of the circuit for eliminating electromagnetic interference and comprises the following steps: acquiring the driving voltage of the circuit to be eliminated and judging whether the driving voltage is less than a preset voltage threshold value; if the driving voltage is less than the preset voltage threshold value, turning on to make the electromagnetic interference eliminating circuit absorb the target electromagnetic interference signal; if the driving voltage is not less than the preset voltage threshold value, turning off to make the electromagnetic interference eliminating circuit discharge.

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