An EMC filter for automobile and its manufacturing method

Abstract

The present invention relates to the technical field of automotive filters, and in particular to an automotive EMC filter and a manufacturing method thereof. The method comprises: inserting a capacitor assembly from below a copper busbar overmolded part into the copper busbar overmolded part; wherein a first X capacitor and a first Y capacitor are grounded and welded, and a second Y capacitor is welded across input lines; and a magnetic ring is sleeved inside the copper busbar overmolded part. Simultaneously, the capacitor assembly is plastic-sealed and baked at high temperature to form a housing. A first electromagnetic interference spectrum and a second electromagnetic interference spectrum are determined in an AC-DC conversion mode to determine an adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring. Furthermore, in a DC-DC conversion mode, the performance stability of the EMC filter under complex dynamic conditions is determined. The present invention can meet higher-performance electromagnetic compatibility requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile filters, and in particular to an EMC filter for automobiles and a manufacturing method thereof. Background Art

[0002] Automotive filters are electronic components used in automotive electronic systems. Their primary function is to filter out unwanted electromagnetic interference (EMI) signals or filters signals of specific frequencies to ensure the normal and stable operation of various electronic devices within the vehicle (such as onboard computers, sensors, and communications equipment). With the continued development of new energy vehicle technology and the large-scale industrialization of new energy vehicles, the requirements for electromagnetic compatibility (EMC) in new energy vehicles are also increasing, requiring more sophisticated filter design to meet higher electromagnetic shielding and filtering requirements.

[0003] Existing automotive filters combine multiple XY capacitors and multiple magnetic cores to form an effective filtering network and improve EMC performance. However, these filters still present challenges: high impedance, complex manufacturing processes, and high manufacturing costs. High impedance can lead to energy loss and signal attenuation during signal transmission, impacting filter performance. High impedance can also cause signal reflection and interference, further degrading EMC performance. This complex manufacturing process can compromise filter quality and reliability, increase production time and overall vehicle manufacturing costs, and reduce production efficiency.

[0004] Therefore, there is an urgent need for an automotive EMC filter and a manufacturing method thereof, which can improve the structural design of the automotive filter, reduce its impedance and improve its filtering capability, further meet higher performance electromagnetic compatibility requirements, and at the same time have lower manufacturing costs and simple manufacturing processes. Summary of the Invention

[0005] To this end, the present invention provides an automotive EMC filter and a manufacturing method thereof, so as to overcome the problems of high impedance, complex structure and low manufacturing efficiency of automotive filters in the prior art.

[0006] To achieve the above objectives, the present invention provides, on the one hand, a method for manufacturing an automotive EMC filter, comprising:

[0007] Step S1: inserting a first X capacitor, a first Y capacitor, and a second Y capacitor from below the copper busbar overmolded component into the copper busbar overmolded component;

[0008] Step S2: Soldering the ground pins of the first X capacitor and the first Y capacitor to the ground portion of the circuit board, and connecting the pins of the second Y capacitor across the input lines of the circuit board inside the copper busbar overmolded component, and soldering them.

[0009] Step S3: After the magnetic ring is nested inside the copper busbar overmolded component, epoxy resin is poured into the first X capacitor and the first Y capacitor, epoxy resin is poured into the second Y capacitor, and then baked at high temperature to form a first shell and a second shell;

[0010] Step S4, performing an electrical conversion performance test on the EMC filter, wherein:

[0011] In an AC-to-DC mode, detecting a first electromagnetic interference spectrum at an input end of the EMC filter when the EMC filter is not connected, and detecting a second electromagnetic interference spectrum at an output end after the EMC filter is connected, determining a first high frequency band and a first low frequency band of the first electromagnetic interference spectrum, determining a second high frequency band and a second low frequency band of the second electromagnetic interference spectrum, and determining an adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring based on an amplitude difference between the first high frequency band and the second high frequency band and an amplitude difference between the first low frequency band and the second low frequency band;

[0012] In the DC-DC mode, under several vehicle operating modes, detecting a third electromagnetic interference spectrum before the EMC filter is connected and a fourth electromagnetic interference spectrum after the EMC filter is connected, and determining the performance stability of the EMC filter during vehicle operation based on the third and fourth electromagnetic interference spectra;

[0013] The vehicle operation modes include vehicle acceleration, vehicle deceleration, and vehicle start-stop.

[0014] Further, in step S4, a first amplitude change rate is determined according to the first electromagnetic interference spectrum, a second amplitude change rate is determined according to the second electromagnetic interference spectrum, a first cutoff frequency of the first electromagnetic interference spectrum is determined according to the first amplitude change rate, and a second cutoff frequency of the second electromagnetic interference spectrum is determined according to the second amplitude change rate.

[0015] Furthermore, in step S4, a first high frequency band and a first low frequency band of a first electromagnetic interference spectrum are determined according to the first cutoff frequency, and a second high frequency band and a second low frequency band of a second electromagnetic interference spectrum are determined according to the second cutoff frequency.

[0016] Furthermore, in step S4, a first amplitude difference between the first high frequency band and the second high frequency band at characteristic frequencies is determined, and a second amplitude difference between the first low frequency band and the second low frequency band at characteristic frequencies is determined. Based on a comparison result of the first amplitude difference with a preset first difference and a comparison result of the second amplitude difference with a preset second difference, an adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring is determined.

[0017] Furthermore, in step S4, determining an adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring includes:

[0018] If the first amplitude difference is greater than the preset first difference, and the second amplitude difference is less than the preset second difference, capacitance parameters of the first X capacitor and / or the first Y capacitor are adjusted.

[0019] Furthermore, in the step S4, determining the adjustment method further includes: if the first amplitude difference is smaller than a preset first difference, and the second amplitude difference is larger than the preset second difference, adjusting the magnetic permeability of the magnetic ring.

[0020] Furthermore, in step S4, under a single vehicle operating mode, the third high frequency band and the third low frequency band of the third electromagnetic interference spectrum are determined, and the fourth high frequency band and the fourth low frequency band of the fourth interference spectrum are determined. The single interference suppression capability of the EMC filter is determined according to the amplitudes corresponding to the third high frequency band, the fourth high frequency band, the third low frequency band and the fourth low frequency band, and the performance stability is determined according to the single interference suppression capability.

[0021] Furthermore, in step S4, the single interference suppression capability of the EMC filter is determined according to the amplitude difference between the third high frequency band and the fourth high frequency band and the amplitude difference between the third low frequency band and the fourth low frequency band.

[0022] Furthermore, in step S4, the weight of the single interference suppression capability in a single vehicle operation mode is determined, and the performance stability is determined according to the corresponding single interference suppression capabilities and corresponding weights in several vehicle operation modes.

[0023] On the other hand, the present invention further provides an EMC filter for automobiles, the EMC filter comprising:

[0024] The capacitor component is inserted into the copper busbar plastic package from the bottom and is fixedly connected to the copper busbar plastic package to suppress differential mode interference and eliminate common mode interference;

[0025] A magnetic ring, which is arranged on the copper busbar plastic coating to suppress low-frequency local noise sources;

[0026] A housing for encapsulating the capacitor assembly and the magnetic ring;

[0027] The capacitor assembly includes a first X capacitor, a first Y capacitor, and a second Y capacitor. The first X capacitor and the first Y capacitor are covered with a first shell, and the second Y capacitor is covered with a second shell. The first shell and the second shell are used to seal the capacitors to prevent them from getting wet.

[0028] Compared with the prior art, the beneficial effect of the present invention is that the present invention inserts the first X capacitor, the first Y capacitor, and the second Y capacitor from the bottom of the copper busbar overmolded part into the interior, ensuring that the capacitor is closely integrated with the internal circuit of the copper busbar overmolded part, improving the reliability of the electrical connection, and at the same time welding the ground pins of the first X capacitor and the first Y capacitor to the ground part of the circuit board, and connecting the second Y capacitor pin across the input line of the circuit board and welding, which helps to effectively bypass the differential mode interference signal to the ground, ensuring that common mode interference can be effectively suppressed, and improving the filter's filtering effect on various types of electromagnetic interference. In addition, in the AC to DC mode, the present invention detects the electromagnetic interference spectrum before and after the filter is connected, divides the high frequency band and the low frequency band, and accurately determines the adjustment strategy for key components such as the first X capacitor, the first Y capacitor, and the magnetic ring based on the amplitude difference, so that the EMC filter can improve the optimization performance and stable operation in the scenario where the AC rectification generates complex electromagnetic interference. At the same time, in the DC-DC mode, considering complex dynamic operating conditions such as vehicle acceleration, deceleration, start and stop, the third and fourth electromagnetic interference spectra before and after the filter are connected are detected to evaluate the performance stability of the EMC filter. The filter has low impedance and can accurately suppress interference signals, further meeting higher performance electromagnetic compatibility requirements.

[0029] Furthermore, in AC-DC mode, the present invention detects the electromagnetic interference spectrum before and after the filter is connected, divides it into high-frequency and low-frequency bands, and accurately determines the adjustment strategy for key components such as the first X capacitor, the first Y capacitor, and the magnetic ring based on the amplitude difference. This allows the EMC filter to improve and optimize performance and maintain stable operation in scenarios where AC rectification generates complex electromagnetic interference. Furthermore, in DC-DC mode, the third and fourth electromagnetic interference spectra before and after the filter is connected are detected to assess the performance stability of the EMC filter, considering complex dynamic operating conditions such as vehicle acceleration, deceleration, and start-stop, further meeting higher-performance electromagnetic compatibility requirements.

[0030] Furthermore, the present invention determines the corresponding cutoff frequency by determining the amplitude change rate of the electromagnetic interference spectrum before and after the EMC filter is connected, thereby finding the high-frequency band and the low-frequency band. This facilitates the pairwise comparison of the high-frequency bands before and after the EMC filter is connected, and the pairwise comparison of the low-frequency bands, which helps to specifically find the weak links in the electromagnetic interference spectrum. The filter has low impedance and can accurately suppress interference signals. The preparation process is further optimized to meet higher-performance electromagnetic compatibility performance requirements.

[0031] Furthermore, the present invention determines a first amplitude difference between the characteristic frequencies of the first high frequency band and the second high frequency band, and determines a second amplitude difference between the characteristic frequencies of the first low frequency band and the second low frequency band. Based on a comparison result of the first amplitude difference with a preset first difference, and a comparison result of the second amplitude difference with a preset second difference, an adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring is determined. This eliminates the need for blindly replacing filter components and instead provides a "targeted approach" based on actual electromagnetic interference characteristics, enabling the filter to have low impedance and accurately suppress interference signals. This significantly improves the accuracy of filter optimization and meets higher-performance electromagnetic compatibility requirements.

[0032] Furthermore, the present invention determines the single interference suppression capability of the EMC filter in a single vehicle operating mode based on the third electromagnetic interference spectrum and the fourth interference spectrum before and after the EMC filter is connected, and determines the performance stability of the EMC filter during vehicle operation based on the corresponding single interference suppression capabilities in several vehicle operating modes, so that the filter has low impedance and can accurately suppress interference signals, further meeting higher-performance electromagnetic compatibility performance requirements.

[0033] Furthermore, the automotive EMC filter provided by the present invention has a simple overall structure, a small number of capacitors, and an easier-to-control production process of the filter, thereby reducing production errors and manufacturing costs. The final EMC filter can be obtained by simply welding circuit resistors and potting with epoxy resin, which reduces the manufacturing difficulty, further facilitates fault location and repair, has low impedance performance, can accurately suppress interference signals, and meets higher-performance electromagnetic compatibility performance requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 1. A diagram showing the steps of a method for manufacturing an automotive EMC filter according to an embodiment of the present invention;

[0035] Figure 2 A diagram illustrating steps for determining an adjustment method for a first X capacitor, a first Y capacitor, and a magnetic ring according to an embodiment of the present invention;

[0036] Figure 3 A diagram illustrating the steps for determining the performance stability of an EMC filter under complex dynamic conditions according to an embodiment of the present invention;

[0037] Figure 4 A diagram showing the steps for determining the cutoff frequency according to an embodiment of the present invention;

[0038] Figure 5 1 is an external structural diagram of an EMC filter according to an embodiment of the present invention;

[0039] Figure 6 This is a diagram showing the internal structure of an EMC filter according to an embodiment of the present invention;

[0040] In the figure, 1, copper busbar plastic coating; 2, magnetic ring; 3, first shell; 4, second shell; 5, first X capacitor; 6, first Y capacitor; 7, second Y capacitor. DETAILED DESCRIPTION

[0041] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0042] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0043] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0044] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0045] See also Figures 1 to 3 As shown, Figure 1 FIG1 is a step diagram of a method for manufacturing an automotive EMC filter according to an embodiment of the present invention. Figure 2 This is a diagram showing steps for determining an adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring according to an embodiment of the present invention. Figure 3 This is a diagram of the steps for determining the performance stability of an EMC filter under complex dynamic conditions according to an embodiment of the present invention. Specifically, the present invention provides a method for manufacturing an automotive EMC filter, comprising:

[0046] Step S1: inserting a first X capacitor, a first Y capacitor, and a second Y capacitor from below the copper busbar overmolded component into the copper busbar overmolded component;

[0047] Step S2: Soldering the ground pins of the first X capacitor and the first Y capacitor to the ground portion of the circuit board, and connecting the pins of the second Y capacitor across the input lines of the circuit board inside the copper busbar overmolded component, and soldering them.

[0048] Step S3: After the magnetic ring is nested inside the copper busbar overmolded component, epoxy resin is poured into the first X capacitor and the first Y capacitor, epoxy resin is poured into the second Y capacitor, and then baked at high temperature to form a first shell and a second shell;

[0049] Step S4, performing an electrical conversion performance test on the EMC filter, wherein:

[0050] In an AC-to-DC mode, detecting a first electromagnetic interference spectrum at an input end of the EMC filter when the EMC filter is not connected, and detecting a second electromagnetic interference spectrum at an output end after the EMC filter is connected, determining a first high frequency band and a first low frequency band of the first electromagnetic interference spectrum, determining a second high frequency band and a second low frequency band of the second electromagnetic interference spectrum, and determining an adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring based on an amplitude difference between the first high frequency band and the second high frequency band and an amplitude difference between the first low frequency band and the second low frequency band;

[0051] In the DC-DC mode, under several vehicle operating modes, detecting a third electromagnetic interference spectrum before the EMC filter is connected and a fourth electromagnetic interference spectrum after the EMC filter is connected, and determining the performance stability of the EMC filter during vehicle operation based on the third and fourth electromagnetic interference spectra;

[0052] The vehicle operation modes include vehicle acceleration, vehicle deceleration, and vehicle start-stop.

[0053] Understandably, in new energy vehicles, the power battery will frequently start and stop, accelerate or decelerate. In these modes, the power battery will frequently charge and discharge, and the DC-DC converter will frequently switch operating states, generating complex and variable electromagnetic interference. At the same time, the high-voltage DC power output by the power battery also needs to be stepped down and converted into low-voltage DC power suitable for on-board chargers and low-voltage electronic equipment (such as interior lighting and instrument panels). This process also generates electromagnetic interference. To protect the electronic equipment in the car from interference and maintain normal vehicle operation, an EMC filter is required.

[0054] It is understood that in AC-DC mode, the present invention significantly reduces electromagnetic interference by adjusting key filter components. In DC-DC mode, spectrum detection is performed under different vehicle operating modes to evaluate the performance stability of the EMC filter under complex dynamic conditions, ensuring that it can meet the requirements for electromagnetic interference suppression in practical applications. This not only improves the design efficiency of the EMC filter, but also helps to enhance the electromagnetic compatibility of automobiles and other equipment, reducing the impact of electromagnetic interference on device performance and user experience.

[0055] In a specific embodiment, preferably, a magnetic ring combined EMC filter with a magnetic permeability of 150 Henry / m is selected. In implementation, the value of the magnetic ring can be determined according to actual conditions, which is not specifically limited here and will not be repeated.

[0056] The present invention inserts the first X capacitor, the first Y capacitor, and the second Y capacitor from the bottom of the copper busbar overmolded part into the interior, ensuring that the capacitor is tightly integrated with the internal circuit of the copper busbar overmolded part, improving the reliability of the electrical connection, and at the same time welding the ground pins of the first X capacitor and the first Y capacitor to the ground part of the circuit board, and connecting the second Y capacitor pin across the circuit board input line and welding, which helps to effectively bypass the differential mode interference signal to the ground, ensuring that common mode interference can be effectively suppressed, and improving the filter's filtering effect on various types of electromagnetic interference. In addition, in the AC to DC mode, the present invention detects the electromagnetic interference spectrum before and after the filter is connected, divides the high frequency band and the low frequency band, and accurately determines the adjustment strategy for key components such as the first X capacitor, the first Y capacitor, and the magnetic ring based on the amplitude difference, so that the EMC filter can improve the optimization performance and stable operation in the scenario where AC rectification generates complex electromagnetic interference. At the same time, in the DC-DC mode, considering complex dynamic operating conditions such as vehicle acceleration, deceleration, start and stop, the third and fourth electromagnetic interference spectra before and after the filter are connected are detected to evaluate the performance stability of the EMC filter. The filter has low impedance and can accurately suppress interference signals, further meeting higher performance electromagnetic compatibility requirements.

[0057] See also Figure 4 As shown, it is a step diagram for determining the cutoff frequency in an embodiment of the present invention. Specifically, in step S4, a first amplitude change rate is determined according to the first electromagnetic interference spectrum, a second amplitude change rate is determined according to the second electromagnetic interference spectrum, a first cutoff frequency of the first electromagnetic interference spectrum is determined according to the first amplitude change rate, and a second cutoff frequency of the second electromagnetic interference spectrum is determined according to the second amplitude change rate.

[0058] It is understood that both the first and second electromagnetic interference spectra have corresponding frequency and amplitude values. The first and second amplitude change rates reflect the speed at which the electromagnetic interference amplitude changes with frequency in different frequency bands before and after the electromagnetic interference is connected to the EMC filter, and are important criteria for subsequently determining the corresponding cutoff frequencies. By determining the cutoff frequencies, the high and low frequency bands in the first and second electromagnetic interference spectra can be determined.

[0059] In a specific embodiment, the first amplitude change rate is the ratio of adjacent amplitude differences to adjacent frequency differences in the first electromagnetic interference spectrum, and the second amplitude change rate is the ratio of adjacent amplitude differences to adjacent frequency differences in the second electromagnetic interference spectrum. Specifically, if the first amplitude change rate is greater than a preset amplitude change rate, the frequency corresponding to the first amplitude change rate is the first cutoff frequency; if the second amplitude change rate is greater than the preset amplitude change rate, the frequency corresponding to the second amplitude change rate is the second cutoff frequency. The preset amplitude change rate ranges from 15% to 30%, and preferably, the preset amplitude change rate is 20%. In implementation, the preset amplitude change rate can be determined based on actual conditions and is not specifically limited here and will not be described in detail.

[0060] In AC-DC mode, the present invention detects the electromagnetic interference spectrum before and after the filter is connected, divides it into high-frequency and low-frequency bands, and accurately determines the adjustment strategy for key components such as the first X capacitor, the first Y capacitor, and the magnetic ring based on the amplitude difference. This allows the EMC filter to improve and optimize performance and maintain stable operation in scenarios where AC rectification generates complex electromagnetic interference. Furthermore, in DC-DC mode, the third and fourth electromagnetic interference spectra before and after the filter is connected are detected to assess the performance stability of the EMC filter, considering complex dynamic operating conditions such as vehicle acceleration, deceleration, and start-stop, further meeting higher-performance electromagnetic compatibility requirements.

[0061] Specifically, in step S4, a first high frequency band and a first low frequency band of a first electromagnetic interference spectrum are determined according to the first cutoff frequency, and a second high frequency band and a second low frequency band of a second electromagnetic interference spectrum are determined according to the second cutoff frequency.

[0062] It can be understood that for the first electromagnetic interference spectrum, the portion with frequencies above the first cutoff frequency is defined as the first high-frequency band, and the portion with frequencies below the first cutoff frequency is defined as the first low-frequency band. Similarly, for the second electromagnetic interference spectrum, the portion above the second cutoff frequency is defined as the second high-frequency band, and the portion below the second cutoff frequency is defined as the second low-frequency band.

[0063] The present invention determines the corresponding cutoff frequency by determining the amplitude change rate of the electromagnetic interference spectrum before and after the EMC filter is connected, thereby finding the high frequency band and the low frequency band. This facilitates the pairwise comparison of the high frequency bands before and after the EMC filter is connected, and the pairwise comparison of the low frequency bands, which helps to specifically find the weak links in the electromagnetic interference spectrum. The filter has low impedance and can accurately suppress interference signals. The preparation process is further optimized to meet higher-performance electromagnetic compatibility performance requirements.

[0064] Specifically, in step S4, a first amplitude difference between the first high frequency band and the second high frequency band at characteristic frequencies is determined, and a second amplitude difference between the first low frequency band and the second low frequency band at characteristic frequencies is determined. Based on a comparison result of the first amplitude difference with a preset first difference and a comparison result of the second amplitude difference with a preset second difference, an adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring is determined.

[0065] Specifically, in step S4, determining an adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring includes:

[0066] If the first amplitude difference is greater than the preset first difference, and the second amplitude difference is less than the preset second difference, capacitance parameters of the first X capacitor and / or the first Y capacitor are adjusted.

[0067] Specifically, in the step S4, determining the adjustment method further includes: if the first amplitude difference is smaller than a preset first difference, and the second amplitude difference is larger than the preset second difference, adjusting the magnetic permeability of the magnetic ring.

[0068] It is understood that determining the first amplitude difference between the characteristic frequencies of the first and second high-frequency bands can intuitively reflect the filter's ability to suppress high-frequency harmonic interference. If the first amplitude difference is greater than a preset value, it means that the filter's actual filtering performance in the high-frequency band is not meeting expectations and component adjustment and optimization are required. Because the first X capacitor and the first Y capacitor play a key role in high-frequency filtering, adjusting the capacitance parameters of the first X capacitor and / or the first Y capacitor, i.e., replacing the first X capacitor and / or the first Y capacitor, can improve the electromagnetic interference suppression effect in the high-frequency band.

[0069] It can be understood that for low frequencies, calculating the second amplitude difference between the first and second low-frequency bands at their characteristic frequencies can accurately assess the filter's ability to mitigate low-frequency ripple interference. If the first amplitude difference is less than the preset first difference, and the second amplitude difference is greater than the preset second difference, indicating poor low-frequency filtering but satisfactory high-frequency filtering, the magnetic ring's permeability can be adjusted, and a higher-permeability magnetic ring can be used to improve low-frequency filtering performance and enhance EMC compatibility.

[0070] In a specific embodiment, if the first amplitude difference is greater than the preset first difference and the second amplitude difference is less than the preset second difference, the first X capacitor and / or the first Y capacitor are replaced with a first X capacitor and / or a first Y capacitor with a higher capacitance value to improve high-frequency filtering capability; if the first amplitude difference is less than the preset first difference and the second amplitude difference is greater than the preset second difference, a magnetic ring with higher permeability is replaced to optimize low-frequency filtering performance. Preferably, the first X capacitor can be replaced with a boxed 2.6nFX capacitor, the first Y capacitor can be replaced with a bare core 2.6nFY capacitor, and the magnetic ring can be replaced with a magnetic ring with a magnetic permeability of 200 Henry / m.

[0071] In a specific embodiment, the high-frequency interference concentrated frequency point and the low-frequency interference concentrated frequency point are selected as characteristic frequencies, and the value range of the preset first difference is 20dB~30dB. Preferably, the value of the preset first difference is 25dB, and the value range of the preset second difference is 20dB~30dB. Preferably, the value of the preset second difference is 25dB; the characteristic frequency, the preset first difference, the value range, the preferred value and the confirmation method of the preset second difference can be selected according to actual conditions, and are not specifically limited here and will not be repeated.

[0072] The present invention determines a first amplitude difference between characteristic frequencies of a first high frequency band and a second high frequency band, and determines a second amplitude difference between characteristic frequencies of a first low frequency band and a second low frequency band. Based on a comparison result of the first amplitude difference with a preset first difference and a comparison result of the second amplitude difference with a preset second difference, an adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring is determined. Blind replacement of filter components is no longer necessary. Instead, the filter is "treated with the right medicine" according to actual electromagnetic interference characteristics, thereby enabling the filter to have low impedance and accurately suppress interference signals. This greatly improves the accuracy of filter optimization and meets higher-performance electromagnetic compatibility requirements.

[0073] Specifically, in step S4, under a single vehicle operating mode, the third high frequency band and the third low frequency band of the third electromagnetic interference spectrum are determined, and the fourth high frequency band and the fourth low frequency band of the fourth interference spectrum are determined. The single interference suppression capability of the EMC filter is determined according to the amplitudes corresponding to the third high frequency band, the fourth high frequency band, the third low frequency band and the fourth low frequency band, and the performance stability is determined according to the single interference suppression capability.

[0074] It is understandable that the degree of electromagnetic interference generated inside the car varies under different car operating modes. Therefore, in a single car operating mode, the third high frequency band and the third low frequency band of the third electromagnetic interference spectrum when the EMC filter is not connected are determined, and the fourth high frequency band and the fourth low frequency band of the fourth electromagnetic interference spectrum when the EMC filter is connected are determined. The third high frequency band, the third low frequency band, the fourth high frequency band and the fourth low frequency band all have corresponding amplitude intensities. Therefore, by comparing the high-frequency filtering conditions and the low-frequency filtering conditions before and after the EMC filter is connected, the single interference suppression capability of the EMC in a single car operating mode can be determined, as well as the performance stability of the EMC filter when facing complex car operating modes during actual car operation.

[0075] In a specific embodiment, the method for confirming the third high frequency band and the third low frequency band of the third electromagnetic interference spectrum and determining the fourth high frequency band and the fourth low frequency band of the fourth electromagnetic interference spectrum is the same as the method for confirming the first high frequency band, the first low frequency band, the second high frequency band, and the second low frequency band, that is, confirming the corresponding cutoff frequency and determining the high frequency band and the low frequency band according to the cutoff frequency.

[0076] Specifically, in step S4, the single interference suppression capability of the EMC filter is determined according to the amplitude difference between the third high frequency band and the fourth high frequency band and the amplitude difference between the third low frequency band and the fourth low frequency band.

[0077] It is understood that the single interference suppression capability refers to the EMC filter's ability to suppress electromagnetic interference in a single vehicle operating mode during a single test. The amplitude difference between the third high-frequency band and the fourth high-frequency band is the difference between the amplitude strength of the third high-frequency band and the fourth high-frequency band at the same frequency. The amplitude difference between the third low-frequency band and the fourth low-frequency band is the difference between the amplitude strength of the third low-frequency band and the fourth low-frequency band at the same frequency. The larger the amplitude difference, the stronger the EMC filter's interference suppression capability within that frequency band and the stronger the single interference suppression capability.

[0078] Specifically, in step S4, the single interference suppression capability is determined according to the amplitude difference between the third high frequency band and the fourth high frequency band at several same frequencies and the amplitude difference between the third low frequency band and the fourth low frequency band at several same frequencies.

[0079] In a specific embodiment, preferably, the single interference suppression capability of the EMC filter is the average of the ratio of the amplitude difference between the third high frequency band and the fourth high frequency band at several same frequencies to the amplitude at the corresponding frequency of the third high frequency band, and the ratio of the amplitude difference between the third low frequency band and the fourth low frequency band at several same frequencies to the amplitude at the corresponding frequency of the fourth low frequency band. In implementation, the single interference suppression capability can be determined according to actual conditions, and is not specifically limited here and will not be elaborated on.

[0080] Specifically, in step S4, the weight of the single interference suppression capability in a single vehicle operation mode is determined, and the performance stability is determined according to the corresponding single interference suppression capabilities and corresponding weights in several vehicle operation modes.

[0081] Understandably, acceleration mode places the highest demands on EMC filters. Whether it's the sudden increase in engine speed in a fuel vehicle, which drastically changes the generator's output characteristics, or the high-current discharge from the power battery in a new energy vehicle, which forces the DC-DC converter to operate at high speed, these conditions can trigger extremely strong and complex electromagnetic interference. The moment a vehicle starts in stop-start mode, the current rises sharply, and the electrical system switches from static to dynamic mode, also generating significant electromagnetic interference. However, this lasts for a shorter period than during acceleration. Furthermore, a vehicle's electromagnetic interference capability is relatively weak in deceleration mode.

[0082] In a specific embodiment, in the vehicle acceleration mode, the weight corresponding to the single interference suppression capability is 0.5; in the vehicle start-stop mode, the weight corresponding to the single interference suppression capability is 0.3; and in the vehicle deceleration mode, the weight corresponding to the single interference suppression capability is 0.2. The performance stability is the average of the weights under several vehicle operating modes and the weighted sum of the corresponding single interference suppression capabilities.

[0083] In a single vehicle operating mode, the present invention determines the single interference suppression capability of the EMC filter based on the third electromagnetic interference spectrum and the fourth interference spectrum before and after the EMC filter is connected. The performance stability of the EMC filter during vehicle operation is determined based on the corresponding single interference suppression capabilities under several vehicle operating modes. This ensures that the filter has low impedance and can accurately suppress interference signals, further meeting higher-performance electromagnetic compatibility performance requirements.

[0084] On the other hand, see Figure 5 、 Figure 6 As shown, Figure 5 1 is an external structural diagram of an EMC filter according to an embodiment of the present invention; Figure 6 This is a diagram showing the internal structure of an EMC filter according to an embodiment of the present invention;

[0085] The present invention provides an automotive EMC filter, which is applied to the manufacturing method of the above-mentioned automotive EMC filter. The EMC filter includes:

[0086] The capacitor component is inserted into the copper busbar overmolded part 1 from below and fixedly connected to the copper busbar overmolded part 1 to suppress differential mode interference and eliminate common mode interference;

[0087] A magnetic ring 2 is provided on the copper busbar overmolded component 1 to suppress low-frequency local noise sources;

[0088] A housing for encapsulating the capacitor assembly and the magnetic ring 2;

[0089] The capacitor assembly includes a first X capacitor 5, a first Y capacitor 6, and a second Y capacitor 7. The first X capacitor 5 and the first Y capacitor 6 are covered with a first housing 3, and the second Y capacitor 7 is covered with a second housing 4. The first housing 3 and the second housing 4 are used to seal the capacitors to prevent them from getting wet.

[0090] It can be understood that the first X capacitor 5 and the first Y capacitor 6 in the capacitor assembly are grounded and welded to suppress common-mode interference and provide grounding protection. The second Y capacitor 7 is connected across the input lines to suppress differential-mode interference, improve EMC performance, and enhance stability. At the same time, epoxy resin is poured into the positions of the first X capacitor 5, the first Y capacitor 6, and the second Y capacitor 7, and then baked at a high temperature to form the first housing 3 and the second housing 4 to fix the first X capacitor 5, the first Y capacitor 6, and the second Y capacitor 7, thereby providing a seal to prevent moisture from entering and affecting the performance of the EMC filter.

[0091] In a specific embodiment, preferably, the first X capacitor 5 is a boxed 2.2nF X capacitor, the first Y capacitor 6 is a bare core 2.2nF Y capacitor, and the second Y capacitor 7 is a bare core 220nF Y capacitor. The welding method of the first X capacitor 5, the first Y capacitor 6, and the second Y capacitor 7 is resistance welding, and the magnetic ring 2 is a ferrite magnetic ring 2. The capacitor assembly and the copper busbar overmolded part 1 are riveted to facilitate the overlapping and locking of the components. At the same time, the material of the copper busbar overmolded part 1 is T2 Y2, which can resist a certain degree of mechanical stress during long-term use and avoid deformation caused by factors such as vehicle driving vibration, which affects the stability of the electrical connection. In implementation, the capacitance values ​​of the first X capacitor 5, the second Y capacitor 7, and the first Y capacitor 6, as well as the welding method of the capacitor assembly, can be determined according to actual conditions and are not specifically limited here and will not be described in detail.

[0092] The automotive EMC filter provided by the present invention has a simple overall structure, a small number of capacitors, and an easier-to-control filter production process, thereby reducing production errors and lowering manufacturing costs. The final EMC filter is obtained simply by circuit resistor welding and epoxy resin potting, which reduces manufacturing difficulty, further facilitates fault location and repair, has low impedance performance, can accurately suppress interference signals, and meets higher-performance electromagnetic compatibility performance requirements.

[0093] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A method for manufacturing an automotive EMC filter, characterized in that: include: Step S1: inserting a first X capacitor, a first Y capacitor, and a second Y capacitor from below the copper busbar overmolded component into the copper busbar overmolded component; Step S2: Solder the pins of the first X capacitor, the first Y capacitor, and the ground pin of the first Y capacitor to corresponding parts of the circuit board, and connect the pins of the second Y capacitor across the input lines of the circuit board inside the copper busbar overmolded component and solder them. Step S3: After the magnetic ring is nested inside the copper busbar overmolded component, epoxy resin is poured into the first X capacitor and the first Y capacitor, epoxy resin is poured into the second Y capacitor, and then baked at high temperature to form a first shell and a second shell; Step S4, performing an electrical conversion performance test on the EMC filter, wherein: In the AC-DC mode, a first electromagnetic interference spectrum of the input end of the EMC filter is detected when the EMC filter is not connected, and a second electromagnetic interference spectrum of the output end is detected after the EMC filter is connected, and a first high frequency band and a first low frequency band of the first electromagnetic interference spectrum are determined, and a second high frequency band and a second low frequency band of the second electromagnetic interference spectrum are determined. An adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring is determined according to an amplitude difference between the first high frequency band and the second high frequency band and an amplitude difference between the first low frequency band and the second low frequency band, wherein: If the first amplitude difference is greater than a preset first difference and the second amplitude difference is less than a preset second difference, adjusting capacitance parameters of the first X capacitor and / or the first Y capacitor; If the first amplitude difference is smaller than the preset first difference, and the second amplitude difference is larger than the preset second difference, adjusting the magnetic permeability of the magnetic ring; The first amplitude difference is determined according to the amplitude difference between the characteristic frequencies of the first high frequency band and the second high frequency band, and the second amplitude difference is determined according to the amplitude difference between the characteristic frequencies of the first low frequency band and the second low frequency band; In the DC-DC mode, under several vehicle operating modes, detecting a third electromagnetic interference spectrum before the EMC filter is connected and a fourth electromagnetic interference spectrum after the EMC filter is connected, and determining the performance stability of the EMC filter during vehicle operation based on the third and fourth electromagnetic interference spectra; The vehicle operation modes include vehicle acceleration, vehicle deceleration, and vehicle start-stop.

2. The method for manufacturing an automotive EMC filter according to claim 1, wherein: In step S4, a first amplitude change rate is determined according to the first electromagnetic interference spectrum, a second amplitude change rate is determined according to the second electromagnetic interference spectrum, a first cutoff frequency of the first electromagnetic interference spectrum is determined according to the first amplitude change rate, and a second cutoff frequency of the second electromagnetic interference spectrum is determined according to the second amplitude change rate.

3. The method for manufacturing an automotive EMC filter according to claim 2, wherein: In step S4, a first high frequency band and a first low frequency band of a first electromagnetic interference spectrum are determined according to the first cutoff frequency, and a second high frequency band and a second low frequency band of a second electromagnetic interference spectrum are determined according to the second cutoff frequency.

4. The method for manufacturing an automotive EMC filter according to claim 3, wherein: In step S4, the adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring is determined according to the comparison result between the first amplitude difference and a preset first difference and the comparison result between the second amplitude difference and a preset second difference.

5. The method for manufacturing an automotive EMC filter according to claim 1, wherein: In step S4, under a single vehicle operating mode, the third high frequency band and the third low frequency band of the third electromagnetic interference spectrum are determined, and the fourth high frequency band and the fourth low frequency band of the fourth interference spectrum are determined. The single interference suppression capability of the EMC filter is determined according to the amplitudes corresponding to the third high frequency band, the fourth high frequency band, the third low frequency band, and the fourth low frequency band. The performance stability is determined according to the single interference suppression capability.

6. The method for manufacturing an automotive EMC filter according to claim 5, wherein: In step S4, the single interference suppression capability of the EMC filter is determined according to the amplitude difference between the third high frequency band and the fourth high frequency band and the amplitude difference between the third low frequency band and the fourth low frequency band.

7. The method for manufacturing an automotive EMC filter according to claim 6, wherein: In step S4, the weight of the single interference suppression capability in a single vehicle operation mode is determined, and the performance stability is determined according to the corresponding single interference suppression capabilities and corresponding weights in a plurality of vehicle operation modes.

8. An automotive EMC filter, applied to the method for manufacturing the automotive EMC filter according to any one of claims 1 to 7, characterized in that: The EMC filter includes: The capacitor component is inserted into the copper busbar plastic package from the bottom and is fixedly connected to the copper busbar plastic package to suppress differential mode interference and eliminate common mode interference; A magnetic ring, which is arranged on the copper busbar plastic coating to suppress low-frequency local noise sources; A housing for encapsulating the capacitor assembly and the magnetic ring; The capacitor assembly includes a first X capacitor, a first Y capacitor, and a second Y capacitor. The first X capacitor and the first Y capacitor are covered with a first shell, and the second Y capacitor is covered with a second shell. The first shell and the second shell are used to seal the capacitors to prevent them from getting wet.

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