Multi-phase Converter Duty Ratio Control for Load Balancing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing technology for balancing load distribution in parallel-connected power semiconductor modules in converters is unstable due to dominant errors in gate signal differences, leading to unstable voltage conversion.
Innovation Solution
A conversion apparatus with multiple phases, each equipped with a converter and a sensor for current detection, where a controller determines a basic duty ratio and a correction duty ratio based on phase current differences, with upper and lower limits set to stabilize the voltage conversion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gate signal level is adjusted based on the difference between actual current and average current to balance load distribution, then load balancing is improved, but voltage conversion stability deteriorates when the difference error is large
Solution Approach 1:
The patent segments the duty ratio control into two independent parts: a common basic duty ratio for all phases and individual correction duty ratios for each phase. This segmentation allows the basic duty ratio to maintain voltage conversion stability while correction duty ratios handle load balancing, preventing the instability caused by large error adjustments in prior art.
Solution Approach 2:
The patent applies partial correction by limiting the correction duty ratio to only compensate for current imbalances within a safe range, rather than fully correcting large errors. This partial action prevents excessive adjustments that would destabilize voltage conversion while still achieving load balancing.
2Reliability
If correction duty ratio is applied to balance phase currents, then current uniformity is improved, but converters may enter stop or directly-coupled states causing instability
Solution Approach 1:
The patent applies preliminary anti-action by setting upper and lower limit values for the correction duty ratio before it can cause harmful effects. These limits prevent the correction duty ratio from pushing converters into stop or directly-coupled states, thereby maintaining operational stability while achieving current uniformity.
Solution Approach 2:
The patent changes the parameter range of the correction duty ratio by imposing limit values, constraining it to operate within a safe window that prevents converters from entering unstable states. This parameter control ensures current balancing without sacrificing operational stability.
Data Source
AI summary
The conversion apparatus includes a conversion module having a plurality of phases, each having a converter capable of performing voltage conversion of discharging electric power of a power source and a sensor detecting phase current flowing in the converter, and in which the phases are electrically connected in parallel, and a controller which controls each converter with a control signal based on a predetermined duty ratio. The controller includes a first determination unit which determines a basic duty ratio common to all of the plurality of phases, a second determination unit which determines a correction duty ratio for correcting the basic duty ratio at each of the converters, and a generation unit which generates a control signal based on the basic duty ratio and the correction duty ratio. The second determination unit determines the correction duty ratio, and sets an upper or lower limit value of the correction duty ratio.