What is the skin effect of the wire harness? How to avoid it?

2024-11-01 16:07:56

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1. Definition The skin effect refers to the phenomenon that when an alternating current passes through a conductor, the current concentrates on the surface of the conductor. For wire harnesses, especially in high-frequency AC circuits, the current is not evenly distributed over the entire cross-section of the wire, but tends to flow near the outer surface of the wire.

2. Causes According to the principle of electromagnetic induction, when an alternating current passes through a wire, an alternating magnetic field is generated around the wire. This magnetic field in turn generates an induced electromotive force inside the wire, and this induced electromotive force hinders the change of current. In the center of the wire, this hindering effect is stronger, causing the current to gradually gather on the surface of the wire. From the perspective of mathematical formulas, for a circular wire with a radius of , the distribution of current density is related to the distance from the center of the wire. Under an alternating magnetic field, the current density approaches zero at the center of the wire, and is relatively large near the surface of the wire.

3. Skin depth Skin depth is an important physical quantity that measures the degree of skin effect. The skin depth in high-frequency circuits decreases with increasing frequency, which means that at high frequencies, the effective cross-section of the conductor decreases and the resistance increases.

4. Impact on wiring harnesses Increased resistance: Since the current is concentrated on the surface of the wire, the effective cross-sectional area of the wire decreases. When the length and resistivity remain unchanged, the reduction in effective cross-sectional area will lead to increased resistance. This will increase the power loss of the wiring harness and generate more heat. Degradation of signal transmission quality: In high-frequency signal transmission, the skin effect will change the inductance and capacitance characteristics of the wiring harness. Because the change in current distribution will affect the distribution of magnetic and electric fields, it will affect the transmission speed and quality of the signal. For example, in the wiring harness of high-speed digital signal transmission, the skin effect may cause signal attenuation, distortion and delay, affecting the communication effect between electronic devices.

5. Countermeasures Use multiple strands of thin wire instead of single strand thick wire: The total surface area of multiple strands of thin wire is larger than that of single strand thick wire, which can make the current distributed in a wider area and reduce the impact of the skin effect. For example, in the windings of some high-frequency transformers, multiple strands of enameled wire are used to wind to reduce the loss caused by the skin effect. Use high-frequency low-loss materials: Selecting materials with appropriate magnetic permeability and electrical conductivity can reduce the skin depth, thereby reducing the skin effect. For example, some special alloy materials have low skin effect loss at high frequencies and can be used in wiring harnesses that require high signal transmission quality.

hv wire harness 7.jpg