DC-DC Converter Duty Ratio Control Under Current Detection Error
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Solution Overview
Problem
DC-to-DC converters face errors in electric current detection, leading to inaccuracies in duty ratio calculation, which affects switching control of the switch.
Innovation Solution
A control device for DC-to-DC converters that calculates the duty ratio based on electric current detection values, using relationship information from past switching cycles to improve accuracy, incorporating correction coefficients and parameters to account for detection errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If electric current detection values are used to calculate duty ratio, then switching control can be performed, but calculation accuracy deteriorates due to detection errors
Solution Approach 1:
The patent uses feedback by calculating the average electric current from detection values, comparing it with the command value, and adjusting the duty ratio calculation based on the relationship information obtained from past switching cycles. This feedback mechanism compensates for detection errors and improves calculation accuracy.
Solution Approach 2:
The patent performs preliminary action by calculating relationship information between average electric current and duty ratio in advance during past switching cycles. This pre-calculated relationship information is then used to correct the duty ratio calculation in the current cycle, improving accuracy before the actual switching control is executed.
2Measurement precision
If correction values are calculated to compensate for inductance errors, then duty ratio accuracy improves, but device complexity increases
Solution Approach 1:
The patent merges the correction for detection errors and inductance errors into a single integrated calculation process. The relationship information between average electric current and duty ratio encompasses both types of errors, allowing compensation for both simultaneously without requiring separate correction mechanisms, thus limiting the increase in device complexity.
3Measurement precision
If relationship information from multiple past switching cycles is used, then calculation accuracy improves, but processing time increases
Solution Approach 1:
The patent applies partial action by using a limited number of past switching cycles (not all historical data) to calculate relationship information. This selective use of past data provides sufficient accuracy for compensation while limiting the processing time and computational load, avoiding the need to process excessive historical information.
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
Enhances the calculation accuracy of the duty ratio, ensuring precise switching control and improved electric current controllability in discontinuous current mode.
Implementation Method 1
transform an input voltage, by repeating accumulation of magnetic energy in the reactor and release of the magnetic energy from the reactor through switching control of the switch
Data Source
AI summary
A control device for a DC-to-DC converter includes: an electric current calculation unit that calculates, based on electric current detection values of an electric current detection unit, an average electric current that is a time average value of electric current flowing through a reactor in one switching cycle; a duty ratio calculation unit that calculates, based on a command value of the average electric current, a duty ratio in a discontinuous current mode; and a switch control unit that performs, based on the calculated duty ratio, switching control of a switch. Moreover, the duty ratio calculation unit is configured to: calculate, based on the duty ratio and the average electric current calculated in a plurality of past switching cycles, relationship information between the average electric current and the duty ratio; and calculate, based on the calculated relationship information and the command value, the duty ratio in a next switching cycle.