Parallel DC-DC Converter Droop Control for Current Sharing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In parallel operation of multiple DC-to-DC converters, unequal load current sharing and power losses lead to circulating currents, which increase efficiency losses and can trigger overcurrent protection, reducing the longevity and reliability of the converters.
Innovation Solution
A dual-active-bridge converter system with a primary and secondary converter connected via a transformer, utilizing an electronic controller to adjust output impedance through a droop compensation module, ensuring equal current sharing and minimizing power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple DC-to-DC converters are coupled in parallel to support a DC load, then the power capacity is increased, but unequal load current sharing occurs leading to circulating currents and increased power losses
Solution Approach 1:
The patent implements a feedback control mechanism where each DC-to-DC converter monitors its own output current and the common bus voltage, and adjusts its operation accordingly. The controller compares the measured current with a reference value and modifies the switching duty cycle to achieve balanced current sharing, thereby eliminating circulating currents and reducing power losses while maintaining increased power capacity through parallel operation.
Solution Approach 2:
The patent dynamically adjusts operational parameters (switching duty cycle, frequency) of each converter based on real-time measurements of current and voltage. By changing these parameters in response to detected imbalances, the system achieves equal current distribution among parallel converters, resolving the contradiction between increased power capacity and reduced energy losses.
2Power
If multiple DC-to-DC converters are coupled in parallel, then the power capacity is increased, but circulating currents can trigger overcurrent protection reducing reliability
Solution Approach 1:
The feedback control mechanism continuously monitors output current and bus voltage, detecting and correcting imbalances before they reach dangerous levels that would trigger overcurrent protection. This real-time adjustment ensures reliable operation of the parallel converter system while maintaining increased power capacity.
Solution Approach 2:
The control system takes preliminary action by preemptively adjusting the operating parameters of converters to prevent circulating currents from reaching levels that would trigger overcurrent protection. This proactive approach eliminates the harmful effect before it can compromise system reliability.
3Power
If multiple DC-to-DC converters are coupled in parallel, then the power capacity is increased, but unmatched current sharing stresses different converters reducing longevity
Solution Approach 1:
The feedback control mechanism ensures equal current sharing by continuously monitoring and adjusting each converter's output, preventing excessive stress on any individual converter. This balanced operation distributes wear and thermal loading uniformly across all parallel converters, maximizing their operational lifespan while maintaining increased power capacity.
Solution Approach 2:
The control system creates an equipotential condition for current sharing by adjusting each converter's output characteristics to match the others, ensuring that all converters operate under equivalent stress conditions. This equalizes the aging process and extends the overall system longevity while preserving the benefits of parallel power capacity.
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
The system achieves balanced current sharing and reduced power losses among DC-to-DC converters, enhancing their reliability and longevity by effectively managing circulating currents.
Implementation Method 1
A first transformer coupled between the first primary alternating current node and the first secondary alternating current node
Data Source
Figure 1A
Figure 1B
Figure 1C~1D
AI summary
A first electronic controller is configured to provide control signals to the control terminals of the semiconductor switches of the first primary converter and the first secondary converter based on a commanded current or target output current (e.g., pursuant to a voltage control mode); the first electronic controller is configured to adjust or increase the output impedance or output resistance of the first secondary converter based on a first droop compensation module (or a first parallel compensation module) responsive to a current error or current difference between the target output current and the observed output current.