Multi-Phase Converter Duty Ratio Control for Current Balance
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Solution Overview
Problem
The existing method for balancing load distribution in semiconductor modules for electric power conversion, as described in Patent Literature 1, is inefficient when the difference in actual current values is large, leading to suboptimal voltage conversion performance due to increased gate signal levels.
Innovation Solution
A conversion apparatus with multiple phases, each equipped with a converter and sensors, utilizes a controller to determine a basic duty ratio and correction duty ratios to balance phase currents, ensuring the basic duty ratio is greater than or equal to the absolute value of the correction duty ratio, thereby reducing drift currents without affecting voltage conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gate signal level is increased or decreased based on a large difference between actual current value and average current value, then the load distribution among semiconductor modules is balanced, but the voltage conversion efficiency deteriorates
Solution Approach 1:
The patent segments the duty ratio control into two independent components: a common duty ratio applied uniformly to all semiconductor modules for voltage conversion, and individual correction duty ratios applied separately to each module for load balancing. This segmentation allows each component to optimize its specific function without interfering with the other, resolving the contradiction between conversion efficiency and load distribution balance.
Solution Approach 2:
The patent applies local quality by implementing phase-specific correction duty ratios that are tailored to the actual current conditions of each individual phase. Instead of applying a uniform correction to all modules, the system adjusts each phase's duty ratio locally based on its specific current deviation from the average, thereby achieving load balancing without compromising the overall voltage conversion efficiency.
2Reliability
If a correction duty ratio is applied to balance phase currents, then drift current is reduced, but the voltage conversion function is affected
Solution Approach 1:
The patent merges two control functions into a unified duty ratio control system: the common duty ratio for voltage conversion and the correction duty ratio for phase current balancing. By combining these controls in the total duty ratio calculation (D_total = D_common + D_correction), the system achieves both voltage conversion and current balancing simultaneously without one affecting the other negatively.
Solution Approach 2:
The patent implements dynamic control by continuously adjusting the correction duty ratio based on real-time phase current measurements. The correction amount is dynamically modified according to the instantaneous difference between each phase's current and the average current, allowing the system to adaptively maintain both voltage conversion efficiency and phase current balance under varying operating conditions.
Data Source
AI summary
A conversion apparatus includes: a conversion module having plural phases, each including a converter and a sensor, in which the plural phases are electrically connected in parallel, and a controller. The controller includes a first unit for determining a basic duty ratio common to all of the plural phases, so that an input or an output of the conversion module becomes equal to a target voltage or a target current, a second unit for determining a correction duty ratio and correcting the basic duty ratio for each of the plural converters, and a generator for generating the control signal based on the basic duty ratio and the correction duty ratio. The second unit determines the correction duty ratio based on a difference between plural phase currents respectively flowing in the plural converters. The basic duty ratio is equal to or greater than an absolute value of the correction duty ratio.