Motor Vehicle Power Converter Filter Harmonic Alignment

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Solution Overview

Problem

Existing converter devices for electric vehicles face inefficiencies in filtering AC voltage components, leading to reduced electromagnetic compatibility and increased stress on batteries due to unwanted alternating currents.

Innovation Solution

The design of filter elements with intermediate circuit capacitance is optimized such that the minimum of their magnitude frequency response aligns with harmonics of the switching frequency, allowing for targeted filtering of AC voltage components, reducing the need for oversized components and improving electromagnetic compatibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If filter elements with intermediate circuit capacitance are used to filter AC voltage components, then electromagnetic compatibility is improved, but the size and cost of filter elements increase due to oversizing

Engineering Contradiction:

Improveelectromagnetic compatibilityVSAvoidsize of filter elements

Core Design Contradiction:

Object-affected harmful factorsVSVolume of stationary object

Solution Approach 1:

The patent changes the parameter of intermediate circuit capacitance value to optimize filtering. By selecting specific capacitance values (e.g., 100 nF to 10 µF) and adjusting the frequency response minima to align with switching frequency harmonics, the filter elements achieve effective AC voltage component filtering without oversizing, thus improving electromagnetic compatibility while controlling physical dimensions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by designing each filter element with a specific frequency response characteristic tailored to target particular harmonics of the switching frequency. The minimum of the magnitude frequency response of each filter element is positioned at specific frequency intervals (e.g., multiples of switching frequency), creating localized filtering effectiveness at critical frequencies rather than uniform broadband filtering, which reduces overall component size.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If multiple filter elements are used to filter different harmonics, then filtering effectiveness is improved, but device complexity increases

Engineering Contradiction:

Improvefiltering effectivenessVSAvoidnumber of filter elements

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies universality by designing filter elements that can handle multiple harmonics simultaneously. Each filter element with intermediate circuit capacitance is configured to create frequency response minima at multiple frequency intervals, allowing a single filter element to attenuate multiple harmonic components (e.g., 2nd, 3rd, 4th harmonics) rather than requiring separate filters for each harmonic, thus reducing overall device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Object-affected harmful factors

If larger intermediate circuit capacitance is used, then voltage ripple filtering is improved, but cost and space requirements increase

Engineering Contradiction:

Improvevoltage rippleVSAvoidspace requirements

Core Design Contradiction:

Object-affected harmful factorsVSVolume of stationary object

Solution Approach 1:

The patent optimizes the parameter of intermediate circuit capacitance by selecting specific values within a defined range (100 nF to 10 µF) rather than using excessively large capacitance values. The frequency response minima are positioned to align with switching frequency harmonics, enabling effective voltage ripple filtering at moderate capacitance levels, thus reducing space requirements while maintaining filtering performance.

Inventive Principle:

Principle #35Parameter changes

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 approach effectively filters AC voltage components, reducing voltage ripples and electromagnetic interference, thereby extending battery life and enhancing the overall efficiency and cost-effectiveness of the converter device.

Implementation Method 1

a plurality of filter elements connected in the intermediate circuit and each having an intermediate circuit capacitance

Methodology Applied

Scientific EffectCapacitance filtering: Capacitance

Implementation Method 2

the minimum of a respective magnitude frequency response of filter elements lies within the frequency interval which includes a harmonic of the switching frequency as the middle frequency

Methodology Applied

Scientific EffectFrequency response filtering: Filter (electronic)

Data Source

PatentEP3334022B1Converter for a motor vehicle and motor vehicle

Publication Date: 2022.02.23 AUDI AG

Figure 1~2
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Figure 4

AI summary

Power converter device for a motor vehicle, comprising a switching unit (2) which is connected to an intermediate circuit (6) of the power converter device (1) and can be operated at a predetermined switching frequency, and several filter elements (7-11) connected in the intermediate circuit (6), each having an intermediate circuit capacitance (15), wherein a minimum of the magnitude frequency response of a respective filter element (7-11) lies within a different frequency interval, which has a harmonic of the switching frequency as its center frequency and an interval length corresponding to the switching frequency, than a respective minimum of the magnitude frequency response of the other filter elements (7-11).