Forward Boost Reverse Buck Converter Zero Crossing Detection
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Solution Overview
Problem
Existing boost control apparatuses face challenges in accurately detecting zero crossing during one-side element control, leading to inappropriate duty control and suboptimal output current, particularly in high-frequency states.
Innovation Solution
A boost control apparatus that includes a current value change amount detecting device to regularly monitor the output current, a determining device to assess if the current is near zero based on change amounts, and a controlling device to switch between first and second duty controls using distinct control parameters, ensuring accurate duty ratio adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional zero crossing detection methods are used, then the detection process is simple, but the detection accuracy and timing precision deteriorate, especially in high-frequency states
Solution Approach 1:
The patent changes the detection parameter from direct current value monitoring to monitoring the change amount (derivative) of current values. By detecting whether the change amount falls within a predetermined range, the system achieves accurate zero crossing detection without complex processing, resolving the contradiction between detection accuracy and process simplicity.
2Manufacturing precision
If duty control is not switched at zero crossing, then the control process is simple, but the output current accuracy deteriorates
Solution Approach 1:
The patent implements feedback control by continuously monitoring the change amount of output current and using this information to determine when zero crossing occurs. This feedback mechanism enables accurate switching between duty controls (first and second control parameters) at the appropriate moment, ensuring output current accuracy while maintaining manageable control complexity through clear switching criteria.
3Loss of energy
If one-side element control is used, then the converter loss is reduced, but the difficulty of detecting zero crossing increases
Solution Approach 1:
The patent applies preliminary action by detecting the change amount of current at multiple predetermined timing points before the actual zero crossing occurs. This allows the system to predict and prepare for the zero crossing event in advance, making detection easier during one-side element control while maintaining low converter loss through continued use of the efficient control mode.
Data Source
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AI summary
A boost control apparatus (30) is provided with: a current value change amount detecting device (310) configured to detect a change amount of output current (IL) that flows through the inductor (L1) in a first predetermined period during one-side element control during which only either one of a first switching element (Q1) and a second switching element (Q2) is driven; a determining device (320) configured to determine that the output current is near zero if the change amount is less than a predetermined threshold value; and a controlling device (330) configured (i) to perform first duty control by using a first control parameter if the output current is not near zero, and (ii) to perform second duty control by using a second control parameter, which is different from the first control parameter, if the output current is near zero.