Ripple Cancellation in Power Conversion Circuits
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Solution Overview
Problem
Conventional power electronic converters generate significant ripples due to switching operations, requiring bulky filtering elements that increase size and cost, and electrolyte capacitors are a common failure point, reducing the lifespan of systems like solar energy systems.
Innovation Solution
The use of coupled inductors to cancel current and voltage ripples at the source, reducing the need for passive filtering elements and improving output voltage quality, while inherent magnetizing inductance compensates for switching ripples, eliminating the need for external inductors and extending system lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional LC or LCL filters are used to filter switching ripples, then ripple reduction is achieved, but the converter size increases due to larger filtering elements
Solution Approach 1:
The patent applies preliminary anti-action by using a resonant tank circuit to generate a compensating signal that opposes and cancels the switching ripples before they appear at the output. The resonant tank is tuned to the switching frequency and produces an equal and opposite ripple signal, effectively canceling the harmful ripples without requiring bulky passive filters.
Solution Approach 2:
The invention converts the harmful switching ripples into a beneficial effect by using them to excite the resonant tank circuit. The switching ripples, instead of being merely filtered out, are utilized to generate the compensating signal needed for ripple cancellation, turning a harmful factor into a useful resource for achieving ripple-free output.
2Object-affected harmful factors
If bulky inductors and capacitors are used to reduce ripples, then output ripple is minimized, but cost and physical size increase
Solution Approach 1:
The resonant tank circuit generates a compensating signal in advance to counteract the switching ripples, eliminating the need for expensive and bulky passive filtering components. This approach reduces manufacturing costs while achieving the same ripple reduction effect.
3Object-affected harmful factors
If electrolyte capacitors are used for filtering, then ripple filtering is effective, but system lifespan is reduced due to capacitor failure
Solution Approach 1:
The patent extracts and eliminates the electrolyte capacitors from the filtering path by using active ripple cancellation through the resonant tank circuit. This removes the reliability bottleneck caused by capacitor degradation, allowing the system to achieve both effective ripple filtering and extended lifespan without relying on short-lived electrolyte capacitors.
4Device complexity
If conventional switching converters are used, then circuit simplicity is maintained, but output voltage quality deteriorates due to large ripples
Solution Approach 1:
The invention merges the ripple cancellation function with the existing switching converter topology by integrating the resonant tank circuit into the conventional design. This combination maintains the simplicity of conventional converters while adding ripple cancellation capability, thereby improving output voltage quality without significantly increasing circuit complexity.
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 results in smaller, cost-effective power conversion circuits with minimal ripples, improved output quality, and extended system lifespan by eliminating the need for bulky filtering components and reducing electrolyte capacitor failures.
Implementation Method 1
The switching circuit is electrically coupled to the coupled inductor and is configured to alternate the flow of the direct current through a first winding of the coupled inductor to produce an alternating current in a second winding of the coupled inductor
Implementation Method 2
The inherent magnetizing inductance of the coupled inductor is configured to compensate for ripples in the alternating current caused by the alternating flow of the direct current through the first winding of the coupled inductor
Data Source
AI summary
A power circuit substantially canceling ripples at the source. The power circuit includes a switching circuit configured to control a power flow between an input and an output, a main storage element electrically connected in series with the switching circuit, and a resonant tank electrically coupled to the switching circuit and configured to compensate for switching ripples in the main storage element. Aspects of the invention can be applied to a converter circuit or to an inverter circuit.