DC Link Module Active Voltage Compensation
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Solution Overview
Problem
High power density and long life expectancy are critical in electronic systems, but dc-link capacitors, particularly aluminum electrolytic capacitors, face reliability issues due to elevated temperatures and high ripple current stress, leading to increased maintenance costs and reduced lifespan, while power film capacitors offer improved reliability but at the cost of volumetric efficiency and higher size.
Innovation Solution
An active series voltage compensator is introduced to reduce dc-link capacitance by processing only the ripple voltage and reactive power, allowing for a dc-link module that maintains system performance without affecting input and output, enabling the use of smaller, more efficient capacitors and extending the life of existing capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If aluminum electrolytic capacitors are used to provide high capacitance values, then the dc-link filtering performance is improved, but the life expectancy is dramatically reduced due to elevated ambient temperatures
Solution Approach 1:
The patent segments the capacitor functions by introducing a separate voltage compensator circuit that handles ripple voltage compensation, allowing the dc-link capacitor to operate under reduced stress conditions. This segmentation enables the capacitor to provide necessary capacitance while the compensator handles the demanding ripple compensation task, thereby extending capacitor life.
Solution Approach 2:
The voltage compensator acts as an intermediary between the dc-link capacitor and the ripple voltage. It introduces an auxiliary voltage source that compensates for ripple voltage, thereby protecting the capacitor from high ripple current stress and thermal degradation, which extends its operational life.
2Reliability
If power film capacitors are used to enhance reliability and lifetime, then the reliability is improved, but the volumetric efficiency is reduced and physical size increases
Solution Approach 1:
The patent changes the operating parameters of the dc-link capacitor by introducing active ripple voltage compensation. This allows the use of smaller capacitors (including aluminum electrolytic types) while maintaining reliability, as the compensator handles the stress that would otherwise require oversized, more reliable but bulkier film capacitors.
3Stability of the object's composition
If high capacitance is used to absorb instantaneous power difference and filter harmonics, then the dc-link voltage stabilization is improved, but the device volume and cost increase
Solution Approach 1:
The voltage compensator serves as an intermediary that actively stabilizes the dc-link voltage by compensating for ripple components. This allows the use of smaller dc-link capacitors while maintaining voltage stabilization performance, as the compensator actively counteracts voltage variations rather than relying solely on passive capacitor sizing.
4Ease of manufacture
If aluminum electrolytic capacitors are used to minimize cost, then the cost is reduced, but the equivalent series resistance is high and ripple current capability is low
Solution Approach 1:
The patent segments the power handling functions by introducing a voltage compensator that handles ripple current compensation. This allows inexpensive aluminum electrolytic capacitors to be used for bulk energy storage while the compensator handles the high-frequency ripple current, reducing the effective ripple current stress on the capacitor and thereby reducing power losses.
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 significantly reduces the required dc-link capacitance, enabling the design of high power density, long-life, cost-effective power electronics systems while improving the reliability and lifespan of existing systems by minimizing stress on capacitors.
Implementation Method 1
a voltage compensation circuit arranged between said input and said output, said voltage compensation circuit adapted to generate a voltage signal to compensate an ac ripple component in a dc voltage signal appearing across the dc link capacitor
Data Source
AI summary
A dc link module for a power circuit comprising a first connector for connecting to a first power conversion circuit, a second connector for connecting to a second power conversion circuit, wherein the second power conversion circuit is connected to a load circuit arranged to at least intermittently operate as a power source to the power circuit, at least one dc link capacitors arranged between said first connector and said second connector for processing a voltage signal received at said first connector or said second connector, and at least one voltage compensation circuits arranged between said first connector and said second connector, said one or more voltage compensation circuits arranged to generate a voltage signal to compensate an ac ripple component in a dc voltage signal appearing across the at least one dc link capacitor.