EV Inverter Pre-Charge Resistor for Coolant Heating Integration

Solution Overview

Problem

Existing electric vehicle systems require separate circuits for pre-charging capacitors and heating coolant, leading to increased components, design space, and manufacturing costs, as well as potential defects.

Innovation Solution

A switching arrangement that integrates a pre-charge resistor to perform both capacitor pre-charging and coolant heating, utilizing the inverter device for current flow in both modes, eliminating the need for additional heating circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a separate electric heating source is used for heating the coolant, then the coolant can be heated effectively, but the system complexity and cost increase

Engineering Contradiction:

Improvecoolant temperatureVSAvoidsystem complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The pre-charge resistor is designed to serve dual functions: pre-charging the intermediate circuit capacitor and heating the coolant. By making the resistor universal, the patent eliminates the need for a separate heating source, thereby reducing system complexity while maintaining effective coolant heating capability

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the pre-charging function and heating function into a single component (the pre-charge resistor). This consolidation combines two previously separate functions into one element, reducing the number of components and simplifying the overall system architecture

Inventive Principle:

Principle #5Merging (Combining)

2Temperature

If the pre-charge resistor is connected directly to the battery terminal for heating mode, then heating can be achieved, but additional circuits and components are required

Engineering Contradiction:

Improvecoolant temperatureVSAvoidcircuit complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The pre-charge resistor is designed to serve dual functions: pre-charging the intermediate circuit capacitor and heating the coolant. By making the resistor universal, the patent eliminates the need for a separate heating source, thereby reducing system complexity while maintaining effective coolant heating capability

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the pre-charging function and heating function into a single component (the pre-charge resistor). This consolidation combines two previously separate functions into one element, reducing the number of components and simplifying the overall system architecture

Inventive Principle:

Principle #5Merging (Combining)

3Temperature

If additional heating components are added to the system, then heating performance is improved, but the cost and potential defects increase

Engineering Contradiction:

Improvecoolant temperatureVSAvoidsystem reliability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The pre-charge resistor is designed to serve dual functions: pre-charging the intermediate circuit capacitor and heating the coolant. By making the resistor universal, the patent eliminates the need for a separate heating source, thereby reducing system complexity while maintaining effective coolant heating capability

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the pre-charging function and heating function into a single component (the pre-charge resistor). This consolidation combines two previously separate functions into one element, reducing the number of components and simplifying the overall system architecture

Inventive Principle:

Principle #5Merging (Combining)

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 component count, saves design space and manufacturing costs, and ensures reliable, efficient operation by integrating pre-charge and heating functions within a single circuit, thereby eliminating the need for additional coolant heaters.

Implementation Method 1

the pre-charge resistor serves to prevent current spikes during charging of the at least one intermediate circuit capacitor

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 2

in a heating mode, serves for heating a coolant

Methodology Applied

Scientific EffectJoule Heating: Joule Heating

Data Source

PatentUS12611947B2Switching arrangement for a motor vehicle and motor vehicle driven at least partially electrically

Publication Date: 2026.04.28 DR ING H C F PORSCHE AG

AI summary

A switching arrangement for a motor vehicle powered at least partially electrically, including at least one inverter for converting a DC voltage of a high-voltage battery into a multi-phase AC voltage for a travel drive, at least one intermediate circuit capacitor connected to the inverter, and at least one pre-charge resistor, wherein, in a pre-charge mode, the pre-charge resistor serves to prevent current spikes during charging of the at least one intermediate circuit capacitor and, in a heating mode, serves for heating a coolant, wherein electrical current flows through the inverter in both the pre-charge mode as well as in the heating mode.