EV Charging Control Circuit With Single-Point Relay State Detection

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Solution Overview

Problem

Existing charging systems for high-voltage electric vehicles require multiple detection modules to monitor the relay state, leading to high costs and space occupation due to the need for voltage comparisons at both ends of the relay.

Innovation Solution

A charging control circuit with a single detection module and a switch module arrangement that allows for state identification based on a sampling voltage, reducing the number of required modules and space occupation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If detection modules are installed at both ends of the relay to monitor voltage, then the reliability of relay state detection is improved, but the cost and space occupation of the charging control circuit increase

Engineering Contradiction:
Improverelay state detection reliabilityVSAvoidcharging control circuit complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the voltage comparison function from the detection modules and integrates it into the control module. Instead of using separate detection modules at both relay ends, the invention removes the need for one detection module by performing voltage comparison centrally in the control module, thereby reducing component count while maintaining detection reliability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the detection and control functions into a single control module. The control module both controls the relay switching and performs the voltage comparison to detect relay state, eliminating the need for separate detection modules and reducing overall system complexity

Inventive Principle:
Principle #5Merging (Combining)

2Measurement precision

If multiple detection modules are used to monitor both ends of the relay, then the accuracy of voltage measurement is improved, but the space occupation of the charging control circuit increases

Engineering Contradiction:
Improvevoltage measurement accuracyVSAvoidcharging control circuit area
Core Design Contradiction:
Measurement precisionVSArea of stationary object

Solution Approach 1:

The control module is designed to perform multiple functions: it both controls the relay switching and measures the voltage to detect relay state. This multi-functional design eliminates the need for dedicated detection modules, reducing space occupation while maintaining measurement capability through the existing control module infrastructure

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Loss of information

If detection modules are installed at both ends of the relay, then the completeness of state information is improved, but the material cost of the charging control circuit increases

Engineering Contradiction:
Improvestate information completenessVSAvoidcharging control circuit cost
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism where the control module measures the voltage at the relay output end and compares it with the expected voltage based on the control signal state. This feedback loop provides complete state information by detecting whether the relay is normally open or normally closed through voltage comparison, eliminating the need for expensive dual-ended detection modules

Inventive Principle:
Principle #23Feedback

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

Reduces material costs and space occupation while effectively identifying the state of the switch module, lowering system failure probability and improving power density.

Implementation Method 1

the detection module is electrically connected to the second end of the switch module to acquire a sampling voltage

Methodology Applied
Scientific EffectVoltage detection: Electric Field

Implementation Method 2

electric vehicles with high-voltage platforms need to be equipped with a voltage boost system to boost the voltage of the low-voltage charging pile to high voltage before charging the high-voltage battery

Methodology Applied
Scientific EffectVoltage boosting: Electromagnetic Induction

Data Source

PatentEP4703191A1Charging control circuit and method, and vehicle
Publication Date: 2026.03.04 SHANGHAI LIXIANG AUTOMOBILE CO LTD
  • EP4703191A1 patent drawingFigure 1~2
  • EP4703191A1 patent drawingFigure 3~5
  • EP4703191A1 patent drawingFigure 6

AI summary

A charging control circuit, comprising a traction driving module (2), an energy storage module (5), a switch module (3), a detection module (4) and a control module, wherein a first end of the traction driving module is electrically connected to a positive electrode of a traction battery (1); a second end of the traction driving module is electrically connected to a negative electrode of the traction battery, a negative electrode end of a charging interface (6) and a second end of the energy storage module; a third end of the traction driving module is electrically connected to a first end of the switch module; a second end of the switch module is respectively electrically connected to a first end of the energy storage module and a positive electrode end of the charging interface; and the detection module is electrically connected to the second end of the switch module, and is used for acquiring a sampled voltage. The charging control circuit meets the requirement that only one detection module is provided in a control circuit to recognize the state of a switch module. In addition, further disclosed are a charging control method and a vehicle.