Power Module Resistor Layout for Accurate Current Sensing

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Solution Overview

Problem

Existing power modules in electrified vehicles face challenges in accurately detecting current flow through internal resistors, leading to heat management issues and increased switching loss due to large current loops and complex current paths.

Innovation Solution

A power module design with substrates on both sides, incorporating a resistor that connects these substrates and reduces current loops by using a connector structure that minimizes contact with the resistor, allowing separate sensing leads to measure current before and after passing through the resistor, thereby improving sensing accuracy and reducing switching loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a resistor is provided inside the power module to detect current, then current sensing capability is improved, but heat generation increases due to large current flowing through the resistor

Engineering Contradiction:

Improvecurrent sensing accuracyVSAvoidheat generation

Core Design Contradiction:

Measurement precisionVSTemperature

Solution Approach 1:

The power module is divided into two separate substrates (first substrate and second substrate) with the resistor positioned between them. This segmentation allows the current path to be split into distinct segments, with the resistor occupying minimal space in the current loop, thereby reducing overall heat generation while maintaining sensing capability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The resistor is positioned in the vertical direction between the first and second substrates, utilizing the vertical dimension rather than occupying horizontal space on a single substrate. This dimensional transition minimizes the resistor's footprint in the current loop plane, reducing inductance and heat generation while preserving current sensing function

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Measurement precision

If a resistor is provided inside the power module, then current detection function is improved, but switching loss increases due to large current loop

Engineering Contradiction:

Improvecurrent detection accuracyVSAvoidswitching loss

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The current loop is segmented into multiple paths with the resistor positioned in a separate branch between the substrates. This segmentation minimizes the area enclosed by the main current loop, reducing loop inductance and consequently decreasing switching loss while maintaining current detection capability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The resistor acts as an intermediary element positioned between the first and second substrates, allowing current measurement without being part of the main high-current switching loop. This intermediary positioning enables accurate current detection while isolating the resistor from the high di/dt switching transients that cause losses

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If a resistor is provided inside the power module, then current sensing capability is improved, but device complexity increases due to heat management and current loop formation requirements

Engineering Contradiction:

Improvecurrent sensing capabilityVSAvoidheat management and current loop formation

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The resistor is integrated into the substrate assembly as a built-in component rather than being a separate external element. The first and second substrates are combined with the resistor positioned between them, forming a unified structure that performs both current sensing and electrical connection functions, thereby reducing overall device complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The resistor serves multiple functions simultaneously: it acts as a current sensing element, provides electrical connection between substrates, and its positioning contributes to heat management by minimizing current loop area. This multi-functionality reduces the need for separate components and simplifies the overall device structure

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

The design reduces current loop inductance, minimizes heat generation, and enhances current sensing accuracy, leading to improved controllability and reduced material costs by optimizing the module's space and component count.

Implementation Method 1

a resistor (for example, a shunt resistor) may be provided inside the power module... a current sensor may be provided outside the power module, or a resistor (for example, a shunt resistor) may be provided inside the power module

Methodology Applied

Scientific EffectOhm's Law: Ohm's Law

Implementation Method 2

a large current flows through the resistor inside the power module, and it is thus necessary to appropriately adjust resulting heat generated by the resistor

Methodology Applied

Scientific EffectJoule Heating: Joule Heating

Data Source

PatentUS12590995B2Power module

Publication Date: 2026.03.31 HYUNDAI MOTOR CO LTD

AI summary

A power module includes a first substrate and a second substrate; a semiconductor chip; a resistor electrically connecting the first substrate and the second substrate while being spaced from the semiconductor chip in the horizontal direction, the resistor including a resistance value greater than a resistance value of the metal layer; a first sensing lead connected to a first end portion of the resistor; and a second sensing lead connected to a second end portion of the resistor.