DC-DC Converter Current Sampling with Timing Correction
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Solution Overview
Problem
There is a need for accurate acquisition of reactor current in DC-DC converters to enable precise control of electric power supplied to a load, as existing methods are influenced by switching delays and dead times, leading to inaccurate sampling and control.
Innovation Solution
A control apparatus for DC-DC converters that includes a current value acquiring unit for sampling at specific intervals within the switching period, a center value estimating unit to calculate the reactor current, and a timing correcting unit to adjust sampling timings based on errors, ensuring accurate timing alignment with the center value of the reactor current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If current sampling is performed at fixed intervals during switching operation, then the control structure remains simple, but timing errors occur due to switching delays and dead times, reducing measurement precision
Solution Approach 1:
The patent makes the sampling timing dynamic by adjusting it based on the actual switching timing of the switching element. Instead of using fixed sampling intervals, the control device determines sampling timings that correspond to specific positions in the reactor current waveform (such as when the current reaches predetermined values), thereby adapting to variations caused by switching delays and dead times while maintaining a relatively simple control structure.
2Measurement precision
If sampling timing is adjusted to compensate for switching delays and dead times, then measurement precision improves, but device complexity increases due to additional timing correction mechanisms
Solution Approach 1:
The patent employs feedback by using the detected reactor current values to determine subsequent sampling timings. The control device samples the current at timings corresponding to when the current reaches predetermined values, and uses this information to continuously adjust sampling timing, thereby compensating for switching delays and dead times without requiring complex external correction mechanisms.
Solution Approach 2:
The system performs self-correction by using its own current detection capability to identify timing errors and adjust sampling accordingly. The reactor current waveform itself provides the reference for determining correct sampling timings, eliminating the need for separate correction circuits or external timing adjustment mechanisms.
3Measurement precision
If carrier frequency is changed based on ripple current comparison, then current control accuracy improves, but loss of time increases due to additional processing steps
Solution Approach 1:
The patent merges multiple functions into a single sampling operation. By sampling the reactor current at timings corresponding to predetermined current values and using these samples for both timing error detection and control calculations, the system achieves accurate current control without requiring separate processing steps, thereby reducing time loss while maintaining high measurement precision.
Data Source
AI summary
A control apparatus of a DC-DC converter includes a reactor and a switching element, repeats an accumulation and a discharge of energy of the reactor by a switching operation of the switching element, and converts a direct-current input voltage to acquire a direct-current output voltage. The control apparatus includes: a current value acquiring unit that acquires current values of the reactor in a current rising section and a current descending section of a current waveform of the reactor at a time interval of a half of a switching period of the switching element; and a center value estimating unit that estimates a center value of a current of the reactor based on the current values acquired in the current rising section and the current descending section.