EMC (Electro Magnetic Compatibility) filter for automobile and manufacturing method thereof

Abstract

The invention relates to the technical field of automobile filters, in particular to an EMC filter for an automobile and a manufacturing method thereof, and the method comprises the steps: inserting a capacitor assembly into a copper bar plastic-coated part from the lower part of the copper bar plastic-coated part; wherein the first X capacitor and the first Y capacitor are grounded and welded, and the second Y capacitor is bridged between input lines and is welded; the method comprises the steps that a copper bar plastic-coated part is arranged, a magnetic ring is arranged in the copper bar plastic-coated part in a sleeved mode, meanwhile, plastic packaging high-temperature baking is conducted on a capacitor assembly to form a shell, a first electromagnetic interference frequency spectrum and a second electromagnetic interference frequency spectrum are determined in an alternating-current-to-direct-current mode, and therefore the adjusting mode of a first X capacitor, a first Y capacitor and the magnetic ring is determined; and the performance stability of the EMC filter under the complex dynamic condition is determined in the direct current-to-direct current mode, and the electromagnetic compatibility performance requirement of higher performance can be met.

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 main function is to filter out unwanted electromagnetic interference (EMI) signals or to filter signals of specific frequencies to ensure that various electronic devices in the car (such as onboard computers, sensors, communication equipment, etc.) can work normally and stably. With the continuous development of new energy vehicle technology and the large-scale industrialization of new energy vehicles, the requirements of new energy vehicles for electromagnetic compatibility (EMC) are also constantly increasing, requiring filter design to be more precise 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 electromagnetic compatibility performance, but there are still the following problems: high impedance, complex preparation process, high manufacturing cost, high impedance may cause energy loss and signal attenuation during signal transmission, affecting the performance of automotive filters, and high impedance may also cause signal reflection and interference, further reducing electromagnetic compatibility performance. Complex automotive filter preparation process will affect the quality and reliability of the filter, increase production time and overall automotive 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 have lower manufacturing costs and simple manufacturing processes. Summary of the invention

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

[0006] To achieve the above object, on the one hand, the present invention provides a method for manufacturing an EMC filter for an automobile, comprising: Step S1, inserting a first X capacitor, a first Y capacitor and a second Y capacitor from below the copper bar plastic package into the copper bar plastic package; Step S2, and welding the ground pins of the first X capacitor and the first Y capacitor to the grounding part 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 part, and welding them; Step S3, after the magnetic ring is nested inside the copper busbar plastic package, epoxy resin is poured into the first X capacitor and the first Y capacitor, epoxy resin is poured into the second Y capacitor, and high-temperature baking is performed 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-to-DC mode, when the EMC filter is not connected, a first electromagnetic interference spectrum of the input end of the EMC filter is detected, and after the EMC filter is connected, a second electromagnetic interference spectrum of the output end is detected, 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, and 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; In the DC-DC mode, in several vehicle operation modes, detecting a third electromagnetic interference spectrum before connecting to the EMC filter and a fourth electromagnetic interference spectrum after connecting to the EMC filter, and determining the performance stability of the EMC filter during vehicle operation according to the third electromagnetic interference spectrum and the fourth electromagnetic interference spectrum; The vehicle operation modes include vehicle acceleration, vehicle deceleration, and vehicle start-stop.

[0007] 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.

[0008] 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.

[0009] Further, in the step S4, a first amplitude difference value at characteristic frequencies of the first high frequency band and the second high frequency band is determined, and a second amplitude difference value at characteristic frequencies of the first low frequency band and the second low frequency band is determined, and an adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring is determined according to a comparison result between the first amplitude difference value and a preset first difference value and a comparison result between the second amplitude difference value and a preset second difference value.

[0010] Furthermore, in the step S4, determining the adjustment method of the first X capacitor, the first Y capacitor and the magnetic ring includes: 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 capacitance parameters of the first X capacitor and / or the first Y capacitor are adjusted.

[0011] 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.

[0012] Furthermore, in step S4, respectively, in a single vehicle operation 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 high frequency band; and the performance stability is determined according to the single interference suppression capability.

[0013] 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.

[0014] 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.

[0015] On the other hand, the present invention further provides an EMC filter for automobiles, the EMC filter comprising: A capacitor component is inserted into the copper bar plastic package from below and fixedly connected to the copper bar plastic package to suppress differential mode interference and eliminate common mode interference; A magnetic ring, which is arranged on the copper busbar plastic package 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.

[0016] 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 bar plastic package into the interior, ensures that the capacitor is closely combined with the internal circuit of the copper bar plastic package, improves the reliability of the electrical connection, and welds the ground pins of the first X capacitor and the first Y capacitor to the grounding part of the circuit board, and bridges the second Y capacitor pin between the circuit board input lines and welds, which helps to effectively bypass the differential mode interference signal to the ground, ensures that the common mode interference can be effectively suppressed, and improves the filtering effect of the filter on various types of electromagnetic interference. And the present invention, in the AC to DC mode, by detecting the electromagnetic interference spectrum before and after the filter is not connected and connected, the high frequency band and the low frequency band are divided, and the adjustment strategy for key components such as the first X capacitor, the first Y capacitor and the magnetic ring is accurately determined according to the amplitude difference, so that the EMC filter can be in the scene where the AC rectification generates complex electromagnetic interference, and improves the optimization performance and stable operation. At the same time, in the DC-to-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 is connected are detected to judge 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.

[0017] Furthermore, in the AC-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 according to the amplitude difference, so that the EMC filter can improve the optimization performance and run stably in the scene where the AC rectification generates complex electromagnetic interference. At the same time, in the DC-DC mode, considering the complex dynamic operating conditions such as automobile acceleration, deceleration, start and stop, the third and fourth electromagnetic interference spectra before and after the filter are connected are detected to judge the performance stability of the EMC filter, which can further meet the higher performance electromagnetic compatibility performance requirements.

[0018] 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, so as to find out the high frequency band and the low frequency band, and facilitates the comparison of the high frequency bands before and after the EMC filter is connected, and the comparison of the low frequency bands before and after the EMC filter is connected, which helps to find out the weak links of the electromagnetic interference in the spectrum in a targeted manner. The filter has low impedance, can accurately suppress interference signals, further optimizes the preparation process, and can meet higher performance electromagnetic compatibility performance requirements.

[0019] Furthermore, the present invention determines a first amplitude difference between a first high frequency band and a second high frequency band at characteristic frequencies, determines a second amplitude difference between a first low frequency band and a second low frequency band at characteristic frequencies, and determines an adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring according to a comparison result between the first amplitude difference and a preset first difference and a comparison result between the second amplitude difference and a preset second difference. The filter components are no longer replaced blindly, and the filter is "treated with the right medicine" according to actual electromagnetic interference characteristics, so that the filter has low impedance, can accurately suppress interference signals, greatly improves the accuracy of filter optimization, and can meet higher performance electromagnetic compatibility performance requirements.

[0020] Furthermore, in the present invention, under a single vehicle operation mode, the single interference suppression capability of the EMC filter is determined according to the third electromagnetic interference spectrum and the fourth interference spectrum before and after the EMC filter is connected, and the performance stability of the EMC filter during the vehicle operation process is determined based on the corresponding single interference suppression capabilities under several vehicle operation modes, so that the filter has low impedance and can accurately suppress interference signals, further meeting higher performance electromagnetic compatibility performance requirements.

[0021] Furthermore, the automotive EMC filter provided by the present invention has a simple overall structure, a small number of capacitors, and an easier control of the filter production process, thereby reducing the production error rate and manufacturing costs. The final EMC filter is obtained by simply welding circuit resistors and filling with epoxy resin, which is easy to manufacture and further facilitates fault location and repair. It has low impedance performance, can accurately suppress interference signals, and meets higher performance electromagnetic compatibility requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A step diagram of a method for manufacturing an automotive EMC filter according to an embodiment of the present invention; Figure 2 A step diagram 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; Figure 3 A diagram showing the steps for determining the performance stability of an EMC filter under complex dynamic conditions according to an embodiment of the present invention; Figure 4 A diagram showing the steps of determining the cut-off frequency according to an embodiment of the present invention; Figure 5 The figure is an external structure diagram of the EMC filter according to the 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; In the figure, 1, plastic-coated copper busbar; 2, magnetic ring; 3, first shell; 4, second shell; 5, first X capacitor; 6, first Y capacitor; 7, second Y capacitor. DETAILED DESCRIPTION

[0023] 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 only used to explain the present invention and are not used to limit the present invention.

[0024] 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 protection scope of the present invention.

[0025] 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 drawings. This is merely 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.

[0026] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] See also Figure 1 to Figure 3 As shown, Figure 1 FIG. 1 is a step diagram of a method for manufacturing an automotive EMC filter according to an embodiment of the present invention. Figure 2 A step diagram 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 The present invention is a step diagram 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 EMC filter for an automobile, comprising: Step S1, inserting a first X capacitor, a first Y capacitor and a second Y capacitor from below the copper bar plastic package into the copper bar plastic package; Step S2, and welding the ground pins of the first X capacitor and the first Y capacitor to the grounding part 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 part, and welding them; Step S3, after the magnetic ring is nested inside the copper busbar plastic package, epoxy resin is poured into the first X capacitor and the first Y capacitor, epoxy resin is poured into the second Y capacitor, and high-temperature baking is performed 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-to-DC mode, when the EMC filter is not connected, a first electromagnetic interference spectrum of the input end of the EMC filter is detected, and after the EMC filter is connected, a second electromagnetic interference spectrum of the output end is detected, 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, and 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; In the DC-DC mode, in several vehicle operation modes, detecting a third electromagnetic interference spectrum before connecting to the EMC filter and a fourth electromagnetic interference spectrum after connecting to the EMC filter, and determining the performance stability of the EMC filter during vehicle operation according to the third electromagnetic interference spectrum and the fourth electromagnetic interference spectrum; The vehicle operation modes include vehicle acceleration, vehicle deceleration, and vehicle start-stop.

[0028] It is understandable that in new energy vehicles, the power battery will frequently start and stop, accelerate or decelerate, and in these modes, the power battery will frequently charge and discharge, and the DC-DC converter will frequently switch working states, resulting in complex and changeable electromagnetic interference; at the same time, the high-voltage direct current output by the power battery also needs to be stepped down and converted into low-voltage direct current suitable for on-board chargers and low-voltage electronic equipment (such as interior lighting, instrument panels, etc.). This process will also generate electromagnetic interference. In order to ensure that the electronic equipment in the car is not interfered with and maintain the normal driving of the vehicle, it is necessary to add an EMC filter; It can be understood that the present invention significantly reduces electromagnetic interference by adjusting key components in the filter in AC-DC mode. In DC-DC mode, spectrum detection is performed in different vehicle operation modes to evaluate the performance stability of the EMC filter under complex dynamic conditions, ensuring that it can meet the requirements for suppressing electromagnetic interference in practical applications, which not only improves the design efficiency of the EMC filter, but also helps to improve the electromagnetic compatibility of equipment such as automobiles and reduce the impact of electromagnetic interference on equipment performance and user experience.

[0029] 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.

[0030] The present invention inserts the first X capacitor, the first Y capacitor and the second Y capacitor from the bottom of the copper bar plastic package into the interior, ensures that the capacitor is closely combined with the internal circuit of the copper bar plastic package, improves the reliability of the electrical connection, and welds the ground pins of the first X capacitor and the first Y capacitor to the grounding part of the circuit board, and bridges the second Y capacitor pin between the circuit board input lines and welds, which helps to effectively bypass the differential mode interference signal to the ground, ensures that the common mode interference can be effectively suppressed, and improves the filtering effect of the filter on various types of electromagnetic interference. And the present invention, in the AC to DC mode, by detecting the electromagnetic interference spectrum before and after the filter is not connected and connected, the high frequency band and the low frequency band are divided, and the adjustment strategy for key components such as the first X capacitor, the first Y capacitor and the magnetic ring is accurately determined according to the amplitude difference, so that the EMC filter can be in the scene where the AC rectification generates complex electromagnetic interference, and improves the optimization performance and stable operation. At the same time, in the DC-to-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 is connected are detected to judge 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.

[0031] 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.

[0032] It can be understood that both the first electromagnetic interference spectrum and the second interference spectrum have corresponding values ​​of frequency and amplitude, and the first amplitude change rate and the second amplitude change rate reflect the speed of amplitude change with frequency in different frequency bands before and after the electromagnetic interference is connected to the EMC filter, which is an important basis for the subsequent determination of the corresponding cutoff frequency. By determining the cutoff frequency, the high frequency band and the low frequency band in the first electromagnetic interference spectrum and the second electromagnetic interference spectrum can be determined.

[0033] In a specific embodiment, the first amplitude change rate is the ratio of the adjacent amplitude difference to the adjacent frequency difference in the first electromagnetic interference spectrum, and the second amplitude change rate is the ratio of the adjacent amplitude difference to the adjacent frequency difference in the second electromagnetic interference spectrum. Specifically, if the first amplitude change rate is greater than the 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%. Preferably, the preset amplitude change rate is 20%. In implementation, the preset amplitude change rate can be determined according to actual conditions, and is not specifically limited here and will not be repeated.

[0034] In the AC-DC mode, the present invention detects the electromagnetic interference spectrum before and after the filter is connected and not 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 according to the amplitude difference, so that the EMC filter can improve the optimization performance and run stably in the scene where the AC rectification generates complex electromagnetic interference. At the same time, in the DC-DC mode, considering the complex dynamic operating conditions such as automobile acceleration, deceleration, start and stop, the third and fourth electromagnetic interference spectra before and after the filter are connected are detected to judge the performance stability of the EMC filter, which can further meet the higher performance electromagnetic compatibility performance requirements.

[0035] 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.

[0036] It can be understood that, for the first electromagnetic interference spectrum, with the first cutoff frequency as the boundary, the portion with a frequency higher than the first cutoff frequency is defined as the first high frequency band, and the portion with a frequency lower than the first cutoff frequency is defined as the first low frequency band. Similarly, for the second electromagnetic interference spectrum, the interval higher than the second cutoff frequency is the second high frequency band, and the interval lower than the second cutoff frequency is the second low frequency band.

[0037] The present invention determines the corresponding cut-off frequency by determining the amplitude change rate of the electromagnetic interference spectrum before and after the EMC filter is connected, so as to find out the high frequency band and the low frequency band, and facilitates the comparison of the high frequency bands before and after the EMC filter is connected, and the comparison of the low frequency bands before and after the EMC filter is connected, which helps to find out the weak links of the electromagnetic interference in the spectrum in a targeted manner. The filter has low impedance, can accurately suppress interference signals, further optimizes the preparation process, and can meet higher performance electromagnetic compatibility performance requirements.

[0038] Specifically, in the 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, and an adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring is determined according to a comparison result between the first amplitude difference and a preset first difference and a comparison result between the second amplitude difference and a preset second difference.

[0039] Specifically, in step S4, determining the adjustment method of the first X capacitor, the first Y capacitor and the magnetic ring includes: 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 capacitance parameters of the first X capacitor and / or the first Y capacitor are adjusted.

[0040] 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.

[0041] It can be understood that by determining the first amplitude difference at the characteristic frequency of the first high frequency band and the second high frequency band, the ability of the filter to suppress high-frequency harmonic interference can be intuitively reflected. If the first amplitude difference is greater than the preset value, it means that the actual filtering performance of the filter in the high frequency band is not as expected, and the components need to be adjusted and optimized. Since the first X capacitor and the first Y capacitor play a key role in high-frequency filtering, the capacitance parameters of the first X capacitor and / or the first Y capacitor are adjusted, that is, the first X capacitor and / or the first Y capacitor are replaced to improve the electromagnetic interference suppression effect in the high frequency band.

[0042] It can be understood that for the low frequency band, the second amplitude difference at the characteristic frequency of the first low frequency band and the second low frequency band is calculated to accurately evaluate the degree to which the filter weakens the 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, it means that the low-frequency filtering is not good but the high frequency meets the standard, then the magnetic permeability of the magnetic ring is adjusted, and a magnetic ring with higher magnetic permeability is used to improve the low-frequency filtering performance and improve the EMC compatibility effect.

[0043] 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, and the first X capacitor and / or the first Y capacitor with a higher capacitance value are replaced to improve the 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, the magnetic ring with higher magnetic permeability is replaced to optimize the 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.

[0044] 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 preset first difference is 25dB, and the value range of the preset second difference is 20dB~30dB, preferably, 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.

[0045] The present invention determines a first amplitude difference between a first high frequency band and a second high frequency band at characteristic frequencies, determines a second amplitude difference between a first low frequency band and a second low frequency band at characteristic frequencies, and determines an adjustment method for the first X capacitor, the first Y capacitor and the magnetic ring according to a comparison result between the first amplitude difference and a preset first difference and a comparison result between the second amplitude difference and a preset second difference. The present invention no longer blindly replaces filter components, but “prescribes the right medicine” according to actual electromagnetic interference characteristics, so that the filter has low impedance, can accurately suppress interference signals, greatly improves the accuracy of filter optimization, and can meet higher performance electromagnetic compatibility performance requirements.

[0046] Specifically, in step S4, respectively, in a single vehicle operation 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 high frequency band, and the performance stability is determined according to the single interference suppression capability.

[0047] It is understandable that the degree of electromagnetic interference generated inside the car is different 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 connected to the EMC filter 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 strengths. Therefore, by comparing the high-frequency filtering and the low-frequency filtering 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.

[0048] In a specific embodiment, the third high frequency band and the third low frequency band of the third electromagnetic interference spectrum are confirmed, and the fourth high frequency band and the fourth low frequency band of the fourth electromagnetic interference spectrum are determined in the same manner as the manner of 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 frequencies, and determining the high frequency band and the low frequency band according to the cutoff frequencies.

[0049] 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.

[0050] It can be understood that the single interference suppression capability refers to the ability of the EMC filter to suppress electromagnetic interference in a single vehicle operation mode under 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 amplitude strength of the fourth high frequency band at the same frequency, and 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 amplitude strength of the fourth low frequency band at the same frequency. The larger the amplitude difference, the stronger the interference suppression capability of the EMC filter in this frequency band, and the stronger the single interference suppression capability.

[0051] 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.

[0052] 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.

[0053] 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 in several vehicle operation modes and the corresponding weights.

[0054] It is understandable that the EMC filter capability is the highest in the acceleration mode. Whether it is the sudden increase in engine speed of fuel vehicles driving the drastic change in the output characteristics of the generator, or the high current discharge of the power battery of new energy vehicles prompting the DC-DC converter to operate at high speed, it will cause extremely strong and complex electromagnetic interference. At the moment of vehicle startup in the start-stop mode, the current rises sharply, and the electrical system switches from static to dynamic, which will also generate a lot of electromagnetic interference, but the duration is shorter than the acceleration period. At the same time, the electromagnetic interference capability of the car in the deceleration mode is weaker.

[0055] 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; 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 and the weighted sum of the corresponding single interference suppression capabilities in several vehicle operation modes.

[0056] The present invention determines the single interference suppression capability of the EMC filter according to the third electromagnetic interference spectrum and the fourth interference spectrum before and after the EMC filter is connected in a single vehicle operation mode, and determines the performance stability of the EMC filter during the vehicle operation process based on the corresponding single interference suppression capabilities under several vehicle operation modes, so that the filter has low impedance, can accurately suppress interference signals, and further meet higher performance electromagnetic compatibility performance requirements.

[0057] On the other hand, see Figure 5 , Figure 6 As shown, Figure 5 The figure is an external structure diagram of the EMC filter according to the 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; The present invention provides an EMC filter for automobiles, which is applied to the manufacturing method of the above-mentioned EMC filter for automobiles, and the EMC filter comprises: A capacitor component is inserted into the copper bar overmolded part 1 from below the copper bar overmolded part 1 and fixedly connected to the copper bar overmolded part 1 to suppress differential mode interference and eliminate common mode interference; A magnetic ring 2, which is arranged on the copper bar plastic package 1, to suppress low-frequency local noise sources; A housing, used to encapsulate the capacitor assembly and the magnetic ring 2; 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 shell 3, and the second Y capacitor 7 is covered with a second shell 4. The first shell 3 and the second shell 4 are used to seal the capacitors to prevent them from getting wet.

[0058] 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 play a role in grounding protection. The second Y capacitor 7 is connected across the input lines to suppress differential mode interference, improve EMC performance, and improve 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 high-temperature baking is performed to form the first shell 3 and the second shell 4 to fix the first X capacitor 5, the first Y capacitor 6, and the second Y capacitor 7, which plays a sealing role, blocks water vapor from entering, and prevents the performance of the EMC filter from being affected.

[0059] In a specific embodiment, preferably, the first X capacitor 5 is a boxed 2.2nFX capacitor, the first Y capacitor 6 is a bare core 2.2nFY capacitor, the second Y capacitor 7 is a bare core 220nFY capacitor, the first X capacitor 5, the first Y capacitor 6 and the second Y capacitor 7 are welded by resistance welding, and the magnetic ring 2 is a ferrite magnetic ring 2, the capacitor assembly is riveted to the copper bar plastic package 1, which is convenient for the overlapping and locking of the parts, and the copper bar plastic package 1 is made of 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 of the first X capacitor 5, the second Y capacitor 7 and the first Y capacitor 6 and the welding method of the capacitor assembly can be determined according to actual conditions, and are not specifically limited here, and will not be repeated.

[0060] The automotive EMC filter provided by the present invention has a simple overall structure and a small number of capacitors. The production process of the filter is easier to control, which reduces the production error rate and the manufacturing cost. The final EMC filter can be obtained by circuit resistance welding and epoxy resin filling. The manufacturing difficulty is low, and fault positioning and repair are further facilitated. It has low impedance performance, can accurately suppress interference signals, and meet higher performance electromagnetic compatibility performance requirements.

[0061] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for manufacturing an EMC filter for an automobile, characterized in that: include: Step S1, inserting a first X capacitor, a first Y capacitor and a second Y capacitor from below the copper bar plastic package into the copper bar plastic package; Step S2, and welding the ground pins of the first X capacitor and the first Y capacitor to the grounding part 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 welding them; Step S3, after the magnetic ring is nested inside the copper busbar plastic package, epoxy resin is poured into the first X capacitor and the first Y capacitor, epoxy resin is poured into the second Y capacitor, and high-temperature baking is performed 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-to-DC mode, when the EMC filter is not connected, a first electromagnetic interference spectrum of the input end of the EMC filter is detected, and after the EMC filter is connected, a second electromagnetic interference spectrum of the output end is detected, 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, and 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; In the DC-DC mode, in several vehicle operation modes, detecting a third electromagnetic interference spectrum before connecting to the EMC filter and a fourth electromagnetic interference spectrum after connecting to the EMC filter, and determining the performance stability of the EMC filter during vehicle operation according to the third electromagnetic interference spectrum and the fourth electromagnetic interference spectrum; 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, characterized in that: 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, characterized in that: 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, characterized in that: In the 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. An adjustment method for the first X capacitor, the first Y capacitor, and the magnetic ring is determined according to a comparison result between the first amplitude difference and a preset first difference and a comparison result between the second amplitude difference and a preset second difference.

5. The method for manufacturing an automotive EMC filter according to claim 4, characterized in that: In the step S4, determining the adjustment method of the first X capacitor, the first Y capacitor and the magnetic ring includes: 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 capacitance parameters of the first X capacitor and / or the first Y capacitor are adjusted.

6. The method for manufacturing an automotive EMC filter according to claim 5, characterized in that: 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.

7. The method for manufacturing an automotive EMC filter according to claim 1, characterized in that: In step S4, respectively, in a single vehicle operation 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 high frequency band, and the performance stability is determined according to the single interference suppression capability.

8. The method for manufacturing an automotive EMC filter according to claim 7, characterized in that: 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.

9. The method for manufacturing an automotive EMC filter according to claim 8, characterized in that: 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 in a plurality of vehicle operation modes and the corresponding weights.

10. An EMC filter for automobiles, applied to the method for manufacturing the EMC filter for automobiles according to any one of claims 1 to 9, characterized in that: The EMC filter comprises: A capacitor component is inserted into the copper bar plastic package from below and fixedly connected to the copper bar plastic package to suppress differential mode interference and eliminate common mode interference; A magnetic ring, which is arranged on the copper busbar plastic package 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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