EMC emission countermeasures for wire harnesses

Abstract

This invention provides a method for reducing noise in wire harnesses and mitigating EMC emissions. [Solution] A method for countermeasures against EMC emissions in a wire harness mounted on a vehicle, wherein a second wire harness, which is grounded to the body and has a length such that it has the same resonance frequency as the noise caused by the DC-DC converter, is run parallel to a first wire harness that connects a high-voltage battery and a DC-DC converter.

Description

Technical Field

[0001] The present disclosure relates to a method for countermeasures against EMC emissions of a wire harness mounted on a vehicle.

Background Art

[0002] Patent Document 1 discloses a vehicle power supply device equipped with a DCDC converter and a high-voltage battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In vehicles equipped with a DCDC converter such as a hybrid electric vehicle (HEV), noise is generated due to the DCDC converter. This noise propagates to the vehicle through a wire harness or the like. Here, depending on the vehicle, due to the impedance of the vehicle, it may have the same resonance as the resonance frequency of the noise, and there is a problem that the noise is amplified in such vehicles.

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide a method for countermeasures against EMC emissions of a wire harness that can reduce the noise of the wire harness.

Means for Solving the Problems

[0006] To solve the above problems, one aspect of the disclosed technology is a method for counteracting EMC emissions of a wire harness mounted on a vehicle, wherein a second wire harness, which is grounded to the body and has a length such that it has the same resonance frequency as the noise resonating from the DC-DC converter, runs parallel to a first wire harness connecting a high-voltage battery and a DC-DC converter. [Effects of the Invention]

[0007] According to the EMC emission countermeasure method for wire harnesses described above, a wire harness grounded to the vehicle is run parallel to the noise propagation path, with a length that gives it the same resonance as the resonant frequency, thereby resonantly canceling out the noise propagating to the vehicle. This makes it possible to reduce the noise of the wire harness. [Brief explanation of the drawing]

[0008] [Figure 1] A diagram illustrating a wire harness structure for realizing an EMC emission countermeasure method for a wire harness according to one embodiment of the present disclosure. [Modes for carrying out the invention]

[0009] <Embodiment> Figure 1 is a schematic diagram illustrating a wire harness structure for realizing an EMC emission countermeasure method for a wire harness mounted on a vehicle 100 according to one embodiment of the present disclosure. In Figure 1, the vehicle 100 is shown as transparent for clarity and simplification of the wire harness structure.

[0010] In the example shown in Figure 1, the vehicle 100 is equipped with a high-voltage battery 110 and a DC-DC converter 120. The high-voltage battery 110 and the DC-DC converter 120 are electrically connected by a high-voltage wire harness (hereinafter referred to as the "first wire harness") 130.

[0011] The high-voltage battery 110 is a battery pack using a rechargeable secondary battery, such as a lithium-ion battery. This high-voltage battery 110 can output the power it stores to the DC-DC converter 120 via the first wire harness (PN wire) 130.

[0012] The DC-DC converter 120 is a power converter (PCU) that receives high-voltage power from the high-voltage battery 110, converts it to a predetermined low-voltage power, and outputs it to a predetermined load (not shown). This DC-DC converter 120 can become a source of noise itself. Noise generated by the DC-DC converter 120 may propagate to the vehicle 100 using the first wire harness 130 as a propagation path.

[0013] To reduce this propagation noise, the wire harness structure of this embodiment includes a dummy wire harness (hereinafter referred to as the "second wire harness") 140, which is wired in parallel with the first wire harness 130 between the high-voltage battery 110 and the DCDC converter 120. This second wire harness 140 has a length that has the same resonance as the noise resonance frequency (hereinafter referred to as the "DCDC noise resonance frequency") caused by the DCDC converter 120. More specifically, the second wire harness 140 is set to a length that is λ / 4 wavelength of the DCDC noise resonance frequency. Furthermore, the second wire harness 140 is grounded to the body GND on the vehicle 100 side (body ground). In other words, this structure is a linear antenna structure that cancels out the noise resonance flowing in the vehicle propagation path.

[0014] For example, if the DC-DC noise resonance frequency is 40 MHz, a second wire harness 140 having a length of λ / 4 wavelength (=1875 mm) that resonates at 40 MHz will be run parallel to the first wire harness 130, and this second wire harness 140 will be grounded to the body GND.

[0015] <Effects and Actions> As described above, according to the method for countermeasures against EMC emissions of the wire harness according to an embodiment of the present disclosure, a second wire harness 140 that is body-grounded and has a length that causes the same resonance as the resonance frequency of the noise caused by the DCDC converter 120 is run in parallel with the first wire harness 130 that connects the high-voltage battery 110 and the DCDC converter 120.

[0016] With this wire harness structure, noise propagated from the first wire harness 130 to the vehicle 100 can be reduced by resonance cancellation between the second wire harness 140.

[0017] Therefore, even if the noise is amplified because the noise resonance frequency of the DCDC converter 120 is the same as the body impedance frequency of the vehicle 100, the second wire harness 140 cancels the noise at the same frequency as the body impedance frequency and shifts it from the DCDC noise resonance frequency. As a result, the noise of the first wire harness 130 can be reduced, and the noise performance of the vehicle 100 can be improved.

[0018] In the above embodiment, the first wire harness 130 that connects the high-voltage battery 110 and the DCDC converter 120 is described as an example, but the present disclosure is similarly applicable to wire harnesses that connect other parts and devices.

Industrial Applicability

[0019] The method for countermeasures against EMC emissions of the wire harness of the present disclosure can be used when it is desired to reduce the noise of the wire harness.

Explanation of Signs

[0020] 100 Vehicle 110 High-voltage battery 120 DCDC converter 130 First wire harness 140 Second wire harness

Claims

[Claim 1] A method for mitigating EMC emissions in wire harnesses installed in vehicles, A second wire harness, grounded to the body and having a length that gives it the same resonance frequency as the noise caused by the DC-DC converter, is run parallel to the first wire harness that connects the high-voltage battery and the DC-DC converter. Methods for mitigating EMC emissions in wire harnesses.

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