Motor Vehicle Power Interface Signal Distortion Compensation
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Solution Overview
Problem
Signal distortion in binary coded signals transmitted through a power interface in motor vehicles is significant due to line inductance and sensor capacitance, making error-free reception difficult, and traditional termination methods result in increased power loss and voltage drop.
Innovation Solution
Compensate for signal distortion by adapting the frequency and phase response of harmonics in the transmitter to match the transmission line characteristics, using a combination of first and third harmonics to generate a signal that minimizes distortion and noise, and employing a rectification circuit and low-pass filter to ensure robust signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If termination resistors of 120 ohms are used at both ends of the transmission line, then signal distortion is reduced, but voltage drop and power loss increase significantly
Solution Approach 1:
The patent changes the termination resistance value from the standard 120 ohms to a lower value (a few ohms) to reduce power loss while maintaining signal quality through harmonic compensation. This parameter change resolves the contradiction by allowing non-nominally tuned termination resistors that minimize voltage drop while still providing adequate signal integrity when combined with harmonic suppression.
2Loss of energy
If low attenuation resistance of a few ohms is used instead of 120 ohms, then voltage drop is reduced, but line inductance causes ringing or attenuated oscillation at each signal edge
Solution Approach 1:
The patent applies preliminary action by suppressing unwanted harmonics in the transmitted signal before it enters the transmission line. By pre-shaping the signal to contain only necessary frequency components (fundamental and selected odd harmonics), the system prevents ringing and oscillation caused by line inductance from developing, allowing the use of low attenuation resistance without signal distortion.
Solution Approach 2:
The patent converts the potentially harmful effect of line inductance into a beneficial by selectively including specific odd harmonics in the transmitted signal. The third and fifth harmonics are used to counteract the oscillating response of the transmission line, transforming the inductance-induced ringing into a controlled signal shape that improves edge steepness while maintaining signal integrity.
3Loss of energy
If only fundamental frequency is used for signal transmission, then power loss is minimized, but edge steepness is insufficient for reliable decoding
Solution Approach 1:
The patent applies partial action by selectively including only the fundamental frequency and specific odd harmonics (third and fifth) in the transmitted signal, rather than all frequency components. This partial inclusion of harmonics provides sufficient edge steepness for reliable decoding while minimizing power loss by excluding unnecessary frequency components.
Solution Approach 2:
The patent changes the frequency spectrum parameters of the transmitted signal by deliberately including specific odd harmonics with controlled amplitudes. The third harmonic amplitude is set to 1/3 to 1/2 of the fundamental, and the fifth harmonic amplitude is set to 1/5 to 1/10 of the fundamental, optimizing both edge steepness and power efficiency.
Data Source
AI summary
A method for reducing signal distortion in the transmission of binary coded signals in a motor vehicle, preferably in a power interface, is characterized in that an edge of the binary coded signal is formed in the transmitter by adapting the frequency and phase response of a harmonic such that the signal distortion to be expected on the entire transmission line can be compensated.