Boost Converter High-Side Switch Dynamic Sizing for Ringing Suppression
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Solution Overview
Problem
Boost converters experience ringing and peak current issues during the transition from the ON to the OFF state due to low resistance and high quality factor in the LC circuit, which affects efficiency and stability.
Innovation Solution
Implementing a high-side switch with an adjustable size, where the size is increased over time when turned on, reducing the drain-to-source on-resistance and minimizing ringing by maintaining a higher resistance initially to prevent significant voltage drops and then decreasing it to enhance current transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the high-side switch is turned on during the transition from ON to OFF state, then a low-resistance path is introduced between the inductor and load, but this causes ringing in the output voltage and large peak current
Solution Approach 1:
The patent applies dynamics by making the high-side switch size adjustable and variable over time. The switch size is dynamically increased during the turn-off transition period, allowing the resistance to change from a higher initial value to a lower final value. This dynamic adjustment resolves the contradiction by temporarily accepting higher resistance to suppress ringing and peak current, then reducing resistance to maintain power efficiency once the transition is complete.
Solution Approach 2:
The patent applies preliminary action by proactively adjusting the high-side switch size before the full turn-off transition occurs. The switch size is increased during the transition period anticipating the potential for ringing and peak current, preventing these harmful effects before they can significantly impact the circuit. This preliminary adjustment of switch parameters resolves the contradiction by preparing the circuit for the upcoming state change.
2Productivity
If the high-side switch size is increased over time, then the drain-to-source on-resistance is reduced to enhance current transfer efficiency, but this may cause voltage drops during the transition period
Solution Approach 1:
The patent applies periodic action by implementing a time-dependent switching strategy where the high-side switch size is adjusted in phases. During the transition period, the switch size is increased in a controlled manner, creating a temporary period with higher resistance to prevent voltage drops and ringing. After the transition completes, the switch operates in a steady state with optimized size for maximum current transfer efficiency. This periodic adjustment resolves the contradiction by separating the circuit operation into distinct phases with different optimization priorities.
Data Source
AI summary
Techniques for reducing ringing arising from L-C coupling in a boost converter circuit during a transition from a boost ON state to a boost OFF state. In an aspect, during an OFF state of the boost converter circuit, the size of the high-side switch coupling a boost inductor to the load is gradually increased over time. In this manner, the on-resistance of the high-side switch is decreased from a first value to a second (lower) value over time, which advantageously reduces ringing (due to high quality factor or Q) when initially entering the OFF state, while maintaining low conduction losses during the remainder of the OFF state. Further techniques are provided for implementing the high-side switch as a plurality of parallel-coupled transistors.