RC Termination Circuit for PLC Signal Attenuation
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Solution Overview
Problem
The existing communication systems using pilot lines for electric and hybrid vehicles face challenges in maintaining the integrity of the PWM signal while achieving constant attenuation of PLC high-frequency carrier currents, leading to potential modifications that violate the ISO/IEC 61851-1 standard.
Innovation Solution
A communication system employing a termination impedance circuit with a capacitor and resistor in series, connected to ground, at each end of the pilot line, which efficiently attenuates PLC high-frequency carrier currents without significantly affecting the PWM signal, using passive components to maintain compliance with the standard.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resistive termination impedances are used to achieve constant attenuation of PLC high-frequency carrier currents, then the attenuation of carrier currents is improved, but the PWM signal is significantly modified and may violate the ISO/IEC 61851-1 standard
Solution Approach 1:
The patent changes the termination impedance from a pure resistive configuration to an RC series configuration. By introducing a capacitor in series with a resistor, the termination impedance becomes frequency-dependent, providing constant attenuation across the PLC frequency range while maintaining PWM signal integrity. The capacitor blocks high-frequency PLC signals while allowing low-frequency PWM signals to pass through with minimal distortion.
Solution Approach 2:
The capacitor acts as an intermediary element that differentiates between PLC high-frequency carrier currents and PWM low-frequency signals. It selectively attenuates the high-frequency component while preserving the low-frequency component, enabling simultaneous operation of both communication protocols without mutual interference.
2Length of stationary object
If the pilot line is made longer to extend communication range, then the coverage area is improved, but propagation and reflection effects of PLC high-frequency carrier currents increase
Solution Approach 1:
The patent modifies the termination impedance parameters by introducing a capacitor in series with a resistor. This RC configuration creates a frequency-selective termination that provides consistent attenuation across the PLC frequency spectrum, compensating for propagation and reflection effects that worsen with increased line length.
3Device complexity
If a simple resistive termination is used, then the device complexity is reduced, but the ability to maintain constant attenuation across different frequencies is insufficient
Solution Approach 1:
The patent enhances the termination circuit by adding a capacitor to the resistive configuration. This creates an RC series circuit that, despite its simplicity, provides frequency-dependent impedance characteristics. The capacitor's reactance varies with frequency, automatically providing the necessary attenuation profile for PLC signals while maintaining compatibility with PWM signals, all without requiring complex active components or control circuits.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution provides a simple, economical, and efficient method to maintain constant attenuation of carrier currents while preserving the PWM signal's integrity, ensuring compatibility with existing standards and electronic chip impedances.
Implementation Method 1
each termination impedance consists of a circuit connected to ground, comprising a capacitor and a resistor arranged in series
Implementation Method 2
each termination impedance consists of a circuit connected to ground, comprising a capacitor and a resistor arranged in series
Data Source
Figure 1~2
AI summary
The invention relates to a system for communicating by means of high-frequency PLC carrier currents over a driving line (8), in order to exchange information between two independent assemblies (2, 4), comprising, at each end, a subassembly (30) for transmitting high-frequency PLC carrier currents, and a termination impedance component (32), said driving line further transmitting, to one of said assemblies which is a receiver (4), a low-frequency square-wave PWM signal that provides information, in particular via the width of the voltage intervals thereof, characterized in that each termination impedance component (32) consists of a circuit that is connected to the ground and comprises a capacitor (36) and a resistor (38) arranged in series, or of any electronic circuit that is closely similar thereto.