Power Module Busbar Stacking for Low Inductance

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Solution Overview

Problem

Existing power conversion devices face a trade-off between improving voltage endurance and reducing inductance, leading to increased size and potential voltage spikes, while also requiring enhanced operability during manufacturing.

Innovation Solution

A power module design featuring a multilayer body with alternating semiconductor and cooling units, where the collector and emitter busbars are arranged in parallel to cancel magnetic fields, reducing inductance and size, and sealed with an insulating sealant to maintain insulation and facilitate efficient cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the distance between power terminals is increased to improve voltage endurance, then insulation is secured, but inductance increases causing voltage spikes

Engineering Contradiction:
Improvevoltage enduranceVSAvoidvoltage spikes
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent transitions from a planar arrangement to a three-dimensional stacked configuration where semiconductor elements and cooling units are alternately arranged in layers. This vertical stacking allows power terminals to be positioned closer together in the horizontal plane while maintaining adequate insulation distance through the vertical dimension, thereby reducing inductance without compromising voltage endurance.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent integrates the cooling units with the semiconductor element structure by alternating their arrangement in a stacked configuration. This merging of cooling functionality into the structural design allows for optimized spatial arrangement of power terminals that reduces inductance while the integrated cooling units manage thermal effects that could influence electrical performance.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If the distance between power terminals is increased to improve voltage endurance, then insulation is secured, but the device size increases

Engineering Contradiction:
Improvevoltage enduranceVSAvoiddevice size
Core Design Contradiction:
ReliabilityVSVolume of stationary object

Solution Approach 1:

By utilizing vertical stacking in the third dimension, the patent achieves the required insulation distance between power terminals without increasing the horizontal footprint of the device. The alternating layers of semiconductor elements and cooling units create a compact three-dimensional structure that maintains voltage endurance while minimizing overall device volume.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent employs a nested arrangement where cooling units are interspersed between semiconductor element layers in a compact stacked configuration. This nesting approach allows multiple functional components to occupy overlapping spatial volumes, achieving the necessary insulation distances without proportionally increasing the external dimensions of the device.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Ease of manufacture

If power terminals are exposed to improve manufacturing operability, then assembly is simplified, but voltage endurance deteriorates

Engineering Contradiction:
Improvemanufacturing operabilityVSAvoidvoltage endurance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent positions power terminals in a configuration where they extend from the stacked structure in a controlled manner that facilitates connection while maintaining adequate insulation distances through the three-dimensional arrangement. This spatial configuration allows for straightforward manufacturing and assembly operations without requiring the terminals to be fully exposed, thereby preserving voltage endurance.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent introduces insulating structures and spacing elements as intermediaries between power terminals and other conductive components. These intermediary elements enable simplified manufacturing and assembly processes by providing clear identification and access points for terminal connection, while simultaneously maintaining the insulation required for voltage endurance.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 solution achieves lower inductance and miniaturization of the power module, enhancing voltage endurance and reducing voltage spikes during switching operations, while improving manufacturing operability by allowing closer busbar placement without compromising insulation.

Implementation Method 1

a multilayer body K made up of a plurality of main body units 10 and cooling units 20 arranged alternately in a left-right direction

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the collector and emitter busbars are arranged in parallel to cancel magnetic fields, reducing inductance

Methodology Applied
Scientific EffectElectromagnetic field generation and cancellation: Electromagnetic Induction

Data Source

PatentEP3101688B1Power module and manufacturing method therefor
Publication Date: 2019.10.02 HITACHI LTD
  • EP3101688B1 patent drawingFigure 1
  • EP3101688B1 patent drawingFigure 2~3
  • EP3101688B1 patent drawingFigure 4

AI summary

A power module or the like is provided in which lower inductance and miniaturization are achieved. The power module includes: main body units (11 to 13), cooling units (21 to 24) which cool the main body units (11 to 13), busbars (51, 52) connected to power terminals (1i, 1j) of the main body units (11 to 13), a casing (W) in which at least contact parts with the busbars (51, 52) are insulative, and a metal member (30) which supports the casing (W). The metal member (30) tightly contacts the casing (W), thereby forming a box with one side opened. At least the main body units (11 to 13) and the busbars (51, 52) are arranged inside the box. An insulating sealant is provided to fill the inside of the box.