Soft-Saturating Inductor Control for Smaller Power Converters
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Solution Overview
Problem
Existing power converters face challenges in reducing size due to the limitations of magnetic components, with techniques like increasing switching frequency or splitting inductors leading to efficiency loss and increased complexity or size.
Innovation Solution
A power converter with a partially saturated inductor designed to handle average and RMS currents, losing a portion of inductance at peak current through soft saturation, using a modified peak current mode controller for control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the switching frequency is increased to reduce inductor size, then the inductor size is reduced, but the converter efficiency decreases and design complexity increases
Solution Approach 1:
The invention changes the operating parameters of the inductor by intentionally allowing it to operate in the saturation region at peak current. By designing the inductor to have controlled soft saturation characteristics, the patent achieves size reduction without the need for excessively high switching frequencies, thereby maintaining converter efficiency while still achieving compact dimensions.
2Volume of moving object
If the inductor is split into multiple inductors in parallel or series configuration to reduce size, then the inductor size is reduced, but the converter's overall size and weight increase
Solution Approach 1:
Instead of splitting the inductor into multiple components, the invention changes the parameter approach by utilizing controlled saturation of a single inductor. This allows the inductor to effectively provide variable inductance (higher average inductance for size reduction, lower saturated inductance for peak current handling) without requiring multiple separate inductor components, thereby avoiding increased converter weight.
3Volume of moving object
If the inductor is designed to operate at higher peak current to reduce size, then the inductor size is reduced, but the inductance stability deteriorates due to saturation
Solution Approach 1:
The invention applies dynamics by allowing the inductor to transition between different operating states - unsaturated during average current operation and softly saturated during peak current operation. This dynamic behavior is controlled through the inductor's magnetic core design, which provides gradual saturation characteristics. The controller adapts to these changes by using modified peak current mode control that accounts for the varying inductance, maintaining stability across different operating conditions.
Solution Approach 2:
The patent implements feedback through modified peak current mode control that monitors the inductor current and adjusts the switching duty cycle accordingly. This feedback mechanism compensates for the inductance variations caused by saturation, ensuring stable converter operation even when the inductor operates in the saturation region during peak current conditions.
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
Enables smaller power converters with improved stability and efficiency, allowing for a wider range of load operations and reduced converter size.
Implementation Method 1
The inductor is further sized to lose a portion of inductance at a peak current as a result of inherent soft saturation in soft saturated inductors or entering a roll-off region
Data Source
AI summary
Devices and methods are provided for a power convertor with a partially saturated inductor. A power converter with a partially saturated inductor includes an inductor sized to support an average current and a root mean square current. The inductor is further sized to lose a portion of inductance at a peak current as a result of entering a roll-off region, wherein the roll-off region is situated between a start of inductance saturation and a full inductance saturation. A method of designing a power converter with a partially saturated inductor includes sizing an inductor of the power converter to support an average current and a root mean square current. The method further includes sizing the inductor to lose a portion of inductance at a peak current as a result of entering a roll-off region, wherein the roll-off region is situated between a start of inductance saturation and a full inductance saturation.