Series Capacitor Current Shaping to Cut Ripple and Peak Current
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Solution Overview
Problem
Conventional rectification systems require large, expensive capacitors for smoothing DC output, which are undesirable due to size and cost constraints, and still leave significant ripple in the current, particularly in applications like battery chargers.
Innovation Solution
An electrical conversion apparatus using multiple capacitors in series with diodes and a constant current device to achieve current shaping, allowing for smaller, less expensive capacitors to replace traditional smoothing capacitors, while providing effective charge and discharge paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large smoothing capacitor is used to reduce current variation, then the output current stability is improved, but the device size and cost increase
Solution Approach 1:
The patent divides a single large smoothing capacitor into multiple smaller capacitors connected in series. This segmentation allows the same current smoothing function to be achieved while using capacitors of reduced individual size and capacitance, thereby resolving the contradiction between output stability and device volume.
2Stability of the object's composition
If a large smoothing capacitor is used to reduce current variation, then the output current stability is improved, but the manufacturing cost increases
Solution Approach 1:
By segmenting the large capacitor requirement into multiple smaller capacitors, the patent reduces the cost per capacitor unit. Although the number of components increases, the overall manufacturing cost decreases because smaller capacitors are cheaper to produce and purchase, thus resolving the contradiction between current stability and manufacturing cost.
3Device complexity
If a simple bridge rectifier is used for AC to DC conversion, then the device complexity is reduced, but the output current variation increases
Solution Approach 1:
The patent maintains the simple bridge rectifier structure but adds a series combination of multiple smaller capacitors at the output stage. This segmentation approach provides effective current smoothing without requiring a complex active regulation circuit, thus resolving the contradiction between device simplicity and output stability.
4Stability of the object's composition
If a large smoothing capacitor is used, then the ripple reduction is improved, but the peak current and harmonic content increase
Solution Approach 1:
By using multiple smaller capacitors in series instead of a single large capacitor, the patent achieves equivalent or better ripple reduction while distributing the charge and discharge currents across multiple components. This segmentation reduces the peak current demand on any single capacitor and decreases harmonic content, resolving the contradiction between ripple reduction and harmful electrical effects.
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 solution reduces the size and cost of capacitors, minimizes ripple, and decreases peak current and harmonic content, leading to reduced component costs and improved power efficiency.
Implementation Method 1
A simple form of smoothing arrangement takes the form of a large capacitor that charges and discharges to compensate for the variations in the output current
Implementation Method 2
a first diode connected in parallel across the first capacitor, a second diode connected in parallel across the second capacitor
Data Source
AI summary
An electrical conversion apparatus for use in current shaping comprising at least two capacitors connected in series between first and second lines, a first diode connected in parallel across the first capacitor, a second diode connected in parallel across the second capacitor, and a constant current device connected in series with the first and second capacitors.