CN113364267A - EMI filter based on improved FOSTER high-frequency model and design method thereof - Google Patents
EMI filter based on improved FOSTER high-frequency model and design method thereof Download PDFInfo
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Abstract
The invention discloses an EMI filter based on an improved FOSTER high-frequency model and a design method thereof, and relates to the field of power technology application, wherein the EMI filter comprises: the device comprises a live wire branch and a zero line branch, wherein a plurality of X capacitor sets, a plurality of Y capacitor sets and a plurality of common mode inductors are connected to the live wire branch and the zero line branch, the X capacitor sets are bridged between the live wire branch and the zero line branch, the Y capacitor sets are bridged between the live wire branch and the zero line branch, and the common mode inductors are bridged between the live wire branch and the zero line branch. By adopting the technical scheme, due to the adoption of the improved Foster network series model structure, when the inductance value of the choke coil is reduced during the test of the EMI filter, the parasitic capacitance can be obviously reduced, the impedance high-frequency characteristic of the choke coil is improved, and the EMI filter can effectively realize the suppression of electromagnetic interference in the full frequency band.
Description
Technical Field
The invention relates to the field of power technology application, in particular to an EMI filter based on an improved FOSTER high-frequency model and a design method thereof.
Background
With the continuous maturation of power electronic technology and the gradual popularization of new material devices such as gallium nitride and silicon carbide, the switching frequency of power electronic equipment is continuously improved, the power density is continuously improved, and the electromagnetic interference problem caused by the continuous improvement is also increasingly serious. Relevant technical specifications are continuously provided by countries and international organizations in the world, such as CISPR22 proposed by CISPR of the International Committee for radio interference Special Committee, EN55022 regulated by European standards, GB9254 issued by China, and the like.
In order to pass the relevant conducted EMI testing of power electronic equipment, engineers often employ the incorporation of EMI filters at the power inlet of the equipment. However, due to the variation of the core material characteristics of the common mode choke coil with frequency and the existence of the winding parasitic capacitance, the impedance and high frequency characteristics of the common mode choke coil are not ideal, which causes insufficient attenuation of the EMI filter in a high frequency band, and further causes the EMI filter to fail a conducted EMI test.
In order to more accurately evaluate the filtering performance of the EMI filter, it is necessary to establish a high-frequency model of the common mode choke in the 150kHz-30MHz conducted interference test range. The researchers proposed to fit the common mode impedance of the common mode choke using the Foster network series model, and the drawback was that the influence of the frequency characteristics of the core material was not considered. In the modeling process, researchers assume that the design of the magnetic core permeability changing along with the frequency is linear, and when the magnetic core material permeability is serious, the model is inaccurate. The model proposed by the scholars can better reflect the influence of the frequency characteristic of the magnetic core material, but the modeling of the magnetic core material requires accurate measurement of the magnetic permeability of the magnetic core material, and the requirement on instruments is high.
Disclosure of Invention
The invention aims to solve the technical problem that an EMI filter based on an improved FOSTER high-frequency model and a design method thereof are provided, and the technical problem that a conducted electromagnetic interference test cannot be passed due to insufficient attenuation of the EMI filter in a high-frequency band in the prior art is solved.
In order to solve the technical problems, the technical scheme of the invention is as follows:
an EMI filter based on an improved FOSTER high frequency model, comprising: the device comprises a live wire branch and a zero line branch, wherein a plurality of X capacitor sets, a plurality of Y capacitor sets and a plurality of common mode inductors are connected to the live wire branch and the zero line branch, the X capacitor sets are bridged between the live wire branch and the zero line branch, the Y capacitor sets are bridged between the live wire branch and the zero line branch, and the common mode inductors are bridged between the live wire branch and the zero line branch.
The number of the common mode inductors is two, the first common mode inductor is bridged between the live wire branch and the zero line branch, and the second common mode inductor is bridged between the live wire branch and the zero line branch;
the number of the X capacitor groups is three, the input ends of the first X capacitor group, the second X capacitor group and the third X capacitor group are connected with the input ends of the first common-mode inductor and the second common-mode inductor in series, and the output ends of the first X capacitor group, the second X capacitor group and the third X capacitor group are connected with the output ends of the first common-mode inductor and the second common-mode inductor in series.
Specifically, the number of the Y capacitor groups is two, the input ends of the first Y capacitor group and the second Y capacitor group are connected in series with the input ends of the first common-mode inductor and the second common-mode inductor, and the output ends of the first Y capacitor group and the second Y capacitor group are connected in series with the output ends of the first common-mode inductor and the second common-mode inductor;
the first Y capacitor bank comprises two Y capacitors which are connected in series, and the second Y capacitor bank comprises two Y capacitors which are connected in series.
And an equivalent load resistor is also connected between the live wire branch and the zero wire branch in a bridging manner, the equivalent load resistor comprises a first resistor and a second resistor, and the first resistor and the second resistor are connected in series.
Wherein the common mode gain in the EMI filter is calculated using the following formula (1):
wherein,
is the impedance value of the first Y capacitor,
is the impedance value of the second Y capacitor.
Wherein the differential mode gain in the EMI filter is calculated using the following equation (2):
wherein,
is the impedance value of the first X capacitor,
is the impedance value of the second X capacitor,
is the impedance value of the third X capacitor.
Also provides a design method of the EMI filter based on the improved FOSTER high-frequency model, which comprises the following steps:
step S1, measuring the common mode and differential mode conducted electromagnetic interference of the device to be measured through the LISN network;
step S2, subtracting the measured value from the corresponding standard value to obtain the common mode and differential mode interference attenuation value of the EMI filter in each frequency band;
step S3, deducing the common mode and differential mode high frequency equivalent circuit of the EMI filter according to the common mode and differential mode interference attenuation values of the EMI filter;
step S4, calculating the value of Y capacitance in the EMI filter through the common mode insertion gain and the differential mode insertion gain of the EMI filter;
step S5, calculating the common mode impedance value of the common mode choke coil required to reach in the frequency band of 150kHz-30 MHz;
step S6, measuring the differential mode inductance of the common mode choke coil, and calculating the value of the X capacitance in the EMI filter according to the differential mode inductance;
step S7, conducting electromagnetic interference test is performed on the EMI filter.
In step S5, the high-frequency impedance characteristics of the common mode choke coil are also optimized.
In step S2, the measured value is subtracted from the corresponding standard value, and a margin of 6dB is added.
By adopting the technical scheme, due to the adoption of the improved Foster network series model structure, when the inductance value of the choke coil is reduced during the test of the EMI filter, the parasitic capacitance can be obviously reduced, the impedance high-frequency characteristic of the choke coil is improved, and the EMI filter can effectively realize the suppression of electromagnetic interference in the full frequency band.
Drawings
FIG. 1 is a topological diagram of an EMI filter based on an improved FOSTER high frequency model according to the present invention;
FIG. 2 is a common mode high frequency equivalent circuit diagram of the EMI filter based on the improved FOSTER high frequency model;
FIG. 3 is a schematic diagram of an improved FOSTER network tandem model of the present invention;
FIG. 4 is a comparison of the fitting effect of the improved FOSTER network tandem model of the present invention;
FIG. 5 is a diagram of a differential mode high frequency equivalent circuit of the EMI filter based on the improved FOSTER high frequency model;
FIG. 6 is a diagram of common mode EMI waveforms for a circuit without EMI filter;
FIG. 7 is a waveform diagram of the differential mode EMI without the EMI filter for the circuit under test according to the present invention;
FIG. 8 is a graph showing the common mode impedance test value and variation trend of the common mode choke of the present invention;
FIG. 9 is a waveform illustrating the results of a conducted interference test using a #1 choke in accordance with the present invention; and
fig. 10 is a waveform diagram of the test results of the conducted interference test using the #2 choke of the present invention.
Detailed Description
The following further describes embodiments of the present invention with reference to the drawings. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
As a first embodiment of the present invention, an EMI filter based on an improved contour high frequency model is proposed, as shown in fig. 1, including: first common mode inductor LCM1A second common mode inductor LCM2A first X capacitor CX1A second X capacitor CX2A third X capacitor CX3The first Y capacitor set CY1And a second Y capacitor bank CY2First X capacitor CX1A second X capacitor CX2A third X capacitor CX3Connected between the live line branch and the zero line branch, and a first Y capacitor bank CY1And a second Y capacitor bank CY2A first common mode inductor L connected in parallel between the live line branch and the zero line branchCM1Arranged on the first X capacitor CX1A second X capacitor CX2Between and with the first X capacitor CX1A second X capacitor CX2Parallel, second common mode inductance LCM2Arranged in a first Y capacitor bank CY1And a third X capacitor CX3Between and with the first Y capacitor bank CY1And a third X capacitor CX3And (4) connecting in parallel.
Wherein, the first Y capacitor bank CY1Comprises two Y capacitors connected in series, and a second capacitor group CY2The circuit comprises two Y capacitors which are connected in series.
Further, as shown in fig. 2, in the common-mode equivalent circuit in the EMI filter, the common-mode gain is calculated by the following formula (1):
wherein,
is the impedance value of the first Y capacitor,
is the impedance value of the second Y capacitor, Z1And Z2The value of (b) is calculated from the following formulae (1.1) and (1.2):
in the common mode equivalent circuit in the above EMI filter, the block portion
For the improved Foster network tandem model, as shown in FIG. 3, C1Characterizing the effect of parasitic capacitance of the common mode choke; the part in the left side frame represents the magnetic core characteristic of the common mode choke coil; the part in the right side frame represents the transmission line characteristic, and the cascade number of the part is determined by the number of the impedance curve resonance peaks in the corresponding frequency band.
The frequency characteristic of the common mode choke differs significantly from the ideal inductance mainly for two reasons: 1. parasitic capacitances exist among winding wires of the common mode choke coil, between the windings and the magnetic core and between the two windings forming the common mode choke coil; 2. the permeability of the common mode choke core material decreases with increasing frequency. In order to better design the common mode choke and to more accurately evaluate the performance of the EMI filter, it is necessary to model the common mode choke at a high frequency in the 150kHz-30MHz frequency band. Since the inductance value of the common mode choke coil is large, the impedance curve thereof often reflects the transmission line characteristics between 10MHz and 30 MHz. It is usually fitted using a Foster network tandem model. However, the common mode choke coil is usually made of manganese-zinc ferrite or nanocrystal. It is characterized by a high initial permeability, but above a certain frequency, its permeability drops rapidly. The Foster network series model, however, does not reflect this impedance non-linearity due to the variation of the core characteristics with frequency very well, and thus an improved Foster network series model is proposed as shown in fig. 3.
The improved Foster network series model fitting effect is better as can be seen from the fitting effect of the model shown in fig. 4, and the leakage flux of the common mode choke coil can be used as the differential mode inductance in the EMI filter. The magnetic potential of the leakage flux mainly drops on the air reluctance between the windings of the common mode choke, not on the core reluctance inside the windings. Since the frequency characteristic of the air permeability is stable, it can be considered that the differential mode inductance is less affected by the frequency characteristic of the magnetic core material. And the inductance value of the differential mode inductor is small, and the impedance curve of the differential mode inductor generally does not have transmission line characteristics in a test frequency band of conducted interference. Therefore, the differential mode equivalent model of the common mode choke coil in the frequency band of 150kHz-30MHz can be fitted by a single-stage Foster network model.
Further, as shown in fig. 5, in the differential mode equivalent circuit in the EMI filter, the differential mode gain is calculated by the following formula (2):
wherein,
is the impedance value of the first X capacitor,
is the impedance value of the second X capacitor,
is the impedance value of the third X capacitor, Z1And Z2The value of (b) is calculated from the following formulae (2.1) and (2.2):
in the differential mode equivalent circuit in the EMI filter described above, the block section
And
is a single stage Foster model.
Based on the EMI filter based on the improved FOSTER high-frequency model proposed in the first embodiment, the second embodiment proposes a corresponding design method of the EMI filter based on the improved FOSTER high-frequency model, and the method is implemented by the following steps:
firstly, a Boost PFC (Power Factor Correction) converter is selected as a device to be tested in the embodiment, specifically, the switching frequency of the Boost PFC converter adopted in the embodiment is 65kHz, and the Power is 1.25Kw, and technicians in the field can replace different types of Boost PFC converters according to actual requirements; measuring common-mode and differential-mode conducted electromagnetic interference of a device to be measured by an LISN (Line Impedance Stabilization Network) to obtain quasi-peak values and average values of common-mode electromagnetic interference shown in fig. 6 and quasi-peak values and average values of differential-mode electromagnetic interference shown in fig. 7; subtracting the measured value from the corresponding standard value (namely quasi-peak value) to obtain common-mode and differential-mode interference attenuation values which are required to be achieved by the EMI filter in each frequency band; the calculation of common-mode and differential-mode interference attenuation values required to be achieved by the EMI filter in each frequency band requires adding a margin of 6dB after a measured value is subtracted from a corresponding standard value; i.e. the common mode interference attenuation value vreq,CMSum and difference mode interference attenuation value vreq,DMThe following formulas (3) and (4) are shown below:
vreq,CM＝vCM-vLimit,CM+6dB (3)
vreq,DM＝vDM-vLimit,DM+6dB (4)
deducing a common-mode and differential-mode high-frequency equivalent circuit of the EMI filter according to the common-mode and differential-mode interference attenuation values of the EMI filter; meanwhile, in a common-mode equivalent circuit in the EMI filter, the common-mode gain is calculated by adopting the following formula (1):
wherein,
is the impedance value of the first Y capacitor,
is the impedance value of the second Y capacitor, Z1And Z2The value of (b) is calculated from the following formulae (1.1) and (1.2):
in the common mode equivalent circuit in the above EMI filter, the block portion
For the improved Foster network tandem model, as shown in FIG. 3, C1Characterizing the effect of parasitic capacitance of the common mode choke; the part in the left side frame represents the magnetic core characteristic of the common mode choke coil; the part in the right side frame represents the transmission line characteristic, and the cascade number of the part is determined by the number of the impedance curve resonance peaks in the corresponding frequency band.
Also, as shown in fig. 5, in the differential mode equivalent circuit in the EMI filter, the differential mode gain is calculated using the following equation (2):
wherein,
is the impedance value of the first X capacitor,
is the impedance value of the second X capacitor,
is the impedance value of the third X capacitor, Z1And Z2The value of (b) is calculated from the following formulae (2.1) and (2.2):
in the differential mode equivalent circuit in the EMI filter described above, the block section
And
is a single stage Foster model.
The value of Y capacitance cannot usually exceed 3300pF due to leakage current limitations. And calculating the value of the Y capacitor in the EMI filter through the common mode insertion gain and the differential mode insertion gain of the EMI filter, wherein the Y capacitor is 1nF in the device to be tested.
The impedance measurement of the Y capacitance was performed and fitted with an E4490A impedance analyzer, and the high frequency equivalent model of the Y capacitance as shown in fig. 5 can be represented by an RLC series model.
The common mode impedance value that the common mode choke coil needs to reach in the frequency band of 150kHz-30MHz is calculated by substituting the corresponding high frequency model and data based on the above equations (1), (1.1) and (1.2), and the result is shown in fig. 8. Meanwhile, the high-frequency impedance characteristic of the common mode choke coil can be optimized in a targeted manner.
Specifically, the frequency characteristics of the common mode choke coil are significantly different from the ideal inductance, mainly for the following two reasons: 1. parasitic capacitances exist among winding wires of the common mode choke coil, between the windings and the magnetic core and between the two windings forming the common mode choke coil; 2. the permeability of the common mode choke core material decreases with increasing frequency. In order to better design the common mode choke and to more accurately evaluate the performance of the EMI filter, it is necessary to model the common mode choke at a high frequency in the 150kHz-30MHz frequency band. Since the inductance value of the common mode choke coil is large, the impedance curve thereof often reflects the transmission line characteristics between 10MHz and 30 MHz. It is usually fitted using a Foster network tandem model. However, the common mode choke coil is usually made of manganese-zinc ferrite or nanocrystal. It is characterized by a high initial permeability, but above a certain frequency, its permeability drops rapidly. The Foster network series model, however, does not reflect this impedance non-linearity due to the variation of the core characteristics with frequency very well, and thus an improved Foster network series model is proposed as shown in fig. 3.
The improved Foster network series model fitting effect is better as can be seen from the fitting effect of the model shown in fig. 4, and the leakage flux of the common mode choke coil can be used as the differential mode inductance in the EMI filter. The magnetic potential of the leakage flux mainly drops on the air reluctance between the windings of the common mode choke, not on the core reluctance inside the windings. Since the frequency characteristic of the air permeability is stable, it can be considered that the differential mode inductance is less affected by the frequency characteristic of the magnetic core material. And the inductance value of the differential mode inductor is small, and the impedance curve of the differential mode inductor generally does not have transmission line characteristics in a test frequency band of conducted interference. Therefore, the differential mode equivalent model of the common mode choke coil in the frequency band of 150kHz-30MHz can be fitted by a single-stage Foster network model.
After the common mode choke coil is preliminarily determined, an impedance curve of the leakage inductance, namely the differential mode inductance, is measured by an E4990A impedance analyzer. And calculating to obtain the value of the X capacitor in the EMI filter according to the requirement of the differential mode attenuation value.
And finally, adding the designed EMI filter into a circuit to be tested, carrying out conducted electromagnetic interference test, and verifying whether the requirement is met. Specifically, a comparative test was performed by a self-wound common mode choke. The magnetic core is made of a nanocrystalline magnetic ring, the material of the magnetic core is FeNbCuSiB (iron-based nanocrystalline alloy), and the initial magnetic conductivity is more than or equal to 80000. The #1 choke had 18 turns and the impedance curve was measured as shown in figure 8. It can be seen that although the impedance value of the #1 choke coil in the low frequency band is much larger than the design requirement, the frequency f corresponding to the first resonance peak of the impedance curve is larger than the frequency frThe #1 choke, being small, has a severely attenuated impedance value in the high frequency band. The impedance value of the choke coil of the #1 in the frequency range of 10MHz-20MHz is smaller than the designed value and does not reach the standard. The EMI filter using the #1 choke was added to the original device under test and the test results are shown in fig. 9. Conducted electromagnetic interference is attenuated to a very low level in a low frequency band, but the frequency band between 4MHz and 20MHz exceeds the standard, and the device to be tested cannot pass the conducted electromagnetic interference test.
The improved Foster network series model provided by the invention is used for fitting and parameter extraction, and the result is shown in Table 1. Increasing the L or C value in the simulation model and keeping the other parameters in the model unchanged, wherein the resonant frequency frThe impedance curve is wholly shifted to the left, and the impedance high-frequency characteristic of the choke coil is further deteriorated; reducing the L or C value in the simulation model and keeping other parameters unchanged when the resonant frequency frThe impedance curve is increased and shifted to the right, and the impedance high-frequency characteristic of the choke coil is improved.
TABLE 1
Therefore, the winding number of the common mode choke coil is properly reduced to 10 turns, and the winding mode is improved from double-layer winding to single-layer winding, and the impedance curve of the #2 choke coil is shown in fig. 8. Similarly, impedance measurement, modeling fitting and parameter extraction are performed on the obtained product. The #2 choke has only one main resonance peak between 150kHz and 30MHz, and does not show transmission line characteristics in a high-frequency band, so that the second-stage parameter is vacant. From the fitting results, the inductance value of the #2 choke coil was reduced, the parasitic capacitance was also significantly reduced, and the impedance high-frequency characteristics were improved. The impedance value of the #2 choke coil reaches the design requirement in the full frequency band of 150kHz-30 MHz.
The EMI filter using the #2 choke was added to the original device under test, and the conducted electromagnetic interference test result is shown in fig. 10, and the device under test passed the conducted interference test.
By adopting the technical scheme, due to the adoption of the improved Foster network series model structure, when the inductance value of the choke coil is reduced during the test of the EMI filter, the parasitic capacitance can be obviously reduced, the impedance high-frequency characteristic of the choke coil is improved, and the EMI filter can effectively realize the suppression of electromagnetic interference in the full frequency band.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, and the scope of protection is still within the scope of the invention.
Claims (9)
1. An EMI filter based on an improved FOSTER high frequency model, comprising: the device comprises a live wire branch and a zero line branch, wherein a plurality of X capacitor sets, a plurality of Y capacitor sets and a plurality of common mode inductors are connected to the live wire branch and the zero line branch, the X capacitor sets are bridged between the live wire branch and the zero line branch, the Y capacitor sets are bridged between the live wire branch and the zero line branch, and the common mode inductors are bridged between the live wire branch and the zero line branch.
2. The EMI filter based on the improved contour high frequency model of claim 1, wherein: the number of the common mode inductors is two, the first common mode inductor is bridged between the live wire branch and the zero line branch, and the second common mode inductor is bridged between the live wire branch and the zero line branch;
the number of the X capacitor groups is three, the input ends of the first X capacitor group, the second X capacitor group and the third X capacitor group are connected with the input ends of the first common-mode inductor and the second common-mode inductor in series, and the output ends of the first X capacitor group, the second X capacitor group and the third X capacitor group are connected with the output ends of the first common-mode inductor and the second common-mode inductor in series.
3. The EMI filter based on the improved contour high frequency model of claim 2, wherein: the number of the Y capacitor groups is two, the input ends of a first Y capacitor group and a second Y capacitor group are connected with the input ends of the first common-mode inductor and the second common-mode inductor in series, and the output ends of the first Y capacitor group and the second Y capacitor group are connected with the output ends of the first common-mode inductor and the second common-mode inductor in series;
the first Y capacitor bank comprises two Y capacitors which are connected in series, and the second Y capacitor bank comprises two Y capacitors which are connected in series.
4. The EMI filter based on the improved contour high frequency model of claim 1, wherein: an equivalent load resistor is connected between the live wire branch and the zero line branch in a bridging manner, the equivalent load resistor comprises a first resistor and a second resistor, and the first resistor is connected with the second resistor in series.
5. The EMI filter based on the improved contour high frequency model of claim 1, wherein: the common mode gain in the EMI filter is calculated using the following equation (1):
wherein,
is the impedance value of the first Y capacitor,
is the impedance value of the second Y capacitor.
6. The EMI filter based on the improved contour high frequency model of claim 1, wherein: the differential mode gain in the EMI filter is calculated using the following equation (2):
wherein,
is the impedance value of the first X capacitor,
is the impedance value of the second X capacitor,
is the impedance value of the third X capacitor.
7. A design method of an EMI filter based on an improved FOSTER high-frequency model is characterized by comprising the following steps:
step S1, measuring the common mode and differential mode conducted electromagnetic interference of the device to be measured through the LISN network;
step S2, subtracting the measured value from the corresponding standard value to obtain the common mode and differential mode interference attenuation value of the EMI filter in each frequency band;
step S3, deducing the common mode and differential mode high frequency equivalent circuit of the EMI filter according to the common mode and differential mode interference attenuation values of the EMI filter;
step S4, calculating the value of Y capacitance in the EMI filter through the common mode insertion gain and the differential mode insertion gain of the EMI filter;
step S5, calculating the common mode impedance value of the common mode choke coil required to reach in the frequency band of 150kHz-30 MHz;
step S6, measuring the differential mode inductance of the common mode choke coil, and calculating the value of the X capacitance in the EMI filter according to the differential mode inductance;
step S7, conducting electromagnetic interference test is performed on the EMI filter.
8. The method for designing an EMI filter based on the improved FOSTER high-frequency model as claimed in claim 7, wherein: in step S5, the high-frequency impedance characteristics of the common mode choke coil are also optimized in a targeted manner.
9. The method for designing an EMI filter based on the improved FOSTER high-frequency model as claimed in claim 7, wherein: in step S2, the measured value is subtracted from the corresponding standard value and a margin of 6dB is added.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110504331.9A CN113364267B (en) | 2021-05-10 | 2021-05-10 | EMI filter based on improved FOSTER high-frequency model and design method thereof |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN203590017U (en) * | 2013-11-28 | 2014-05-07 | 广州视源电子科技股份有限公司 | Electromagnetic interference filtering circuit |
| CN105099165A (en) * | 2014-05-19 | 2015-11-25 | 北京东土科技股份有限公司 | EMC protection and filtering device and method of high voltage power supply |
| KR20190089255A (en) * | 2018-01-22 | 2019-07-31 | 엘지이노텍 주식회사 | Electromagnetic Interference Filter |
| CN110943608A (en) * | 2018-09-21 | 2020-03-31 | 中车株洲电力机车研究所有限公司 | EMI filter for motor driver |
| CN111478578A (en) * | 2020-04-30 | 2020-07-31 | 北京理工大学 | New energy automobile motor controller high voltage direct current power supply electromagnetic interference filter |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203590017U (en) * | 2013-11-28 | 2014-05-07 | 广州视源电子科技股份有限公司 | Electromagnetic interference filtering circuit |
| CN105099165A (en) * | 2014-05-19 | 2015-11-25 | 北京东土科技股份有限公司 | EMC protection and filtering device and method of high voltage power supply |
| KR20190089255A (en) * | 2018-01-22 | 2019-07-31 | 엘지이노텍 주식회사 | Electromagnetic Interference Filter |
| CN110943608A (en) * | 2018-09-21 | 2020-03-31 | 中车株洲电力机车研究所有限公司 | EMI filter for motor driver |
| CN111478578A (en) * | 2020-04-30 | 2020-07-31 | 北京理工大学 | New energy automobile motor controller high voltage direct current power supply electromagnetic interference filter |
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