Parallel DC Converter Droop Control for Balanced Output Current
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Solution Overview
Problem
Existing droop control methods in DC power supply systems with multiple converters fail to appropriately control output currents due to variations in drooping characteristics, leading to unstable DC connections and current imbalances.
Innovation Solution
A power conversion device that includes an output current value acquisition unit, an output voltage value acquisition unit, and a control unit with a correction value generation unit and droop control unit to adjust output currents based on target values and load fluctuations, ensuring balanced current distribution among parallel-connected converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If droop control method is used without information exchange between converters, then system reliability is improved and control simplicity is maintained, but output current balance deteriorates
Solution Approach 1:
The patent implements feedback control by having each power conversion device measure its own output current and voltage, compare these values against target values, and adjust its operation accordingly. The control unit receives detection values from detection units and generates control signals based on the differences between actual and target values, creating a closed-loop feedback system that maintains current balance without requiring communication between devices.
Solution Approach 2:
Each power conversion device independently determines its own output current target value based on its detected output current and voltage values, without needing to exchange information with other converters. The device uses its own operational data to self-adjust and maintain proper current distribution, making the system autonomous and eliminating communication requirements while preserving current balance.
2Stability of the object's composition
If constant current control is applied to eliminate current imbalance, then output current balance is improved, but adaptability to droop control method deteriorates
Solution Approach 1:
The patent employs dynamic control where the output current target value is not fixed but continuously adjusted based on real-time detection of output current and voltage values. The control unit dynamically modifies the target value according to the difference between actual and desired states, allowing the system to adapt to changing load conditions and droop characteristics while maintaining current balance, thus combining benefits of both constant current control and droop control.
Solution Approach 2:
The system changes the output current target value parameter dynamically based on detected operational parameters (output current and voltage). By adjusting this key parameter according to real-time measurements and the difference between actual and target values, the system achieves current balance while remaining compatible with droop control methodology, rather than requiring fixed constant current settings.
3Ease of operation
If output voltage is controlled based on drooping characteristic only, then control simplicity is maintained, but output current control precision deteriorates
Solution Approach 1:
The control unit calculates and sets the output current target value in advance based on detected output current and voltage values before actual power delivery occurs. This preliminary determination of the target value allows the system to proactively compensate for potential imbalances, achieving precise current control while maintaining the simplicity of droop control operation, as the complexity is handled in the calculation phase rather than requiring complex real-time control mechanisms.
Data Source
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AI summary
A power conversion device configured to step-up, step-up/step-down, or step-down DC power input from a DC power supply and output the DC power, the power conversion device being connected to a load in parallel with another power conversion device, the power conversion device including: an output current value acquisition unit; an output voltage value acquisition unit; and a control unit configured to control the output voltage, wherein the control unit includes: a correction value generation unit configured to generate an output current correction value for correcting the output current value based on an output current target value and the output current value; and a droop control unit configured to droop the output voltage target value based on a corrected output current value corrected by the output current correction value, and the control unit controls the output voltage based on the output voltage target value drooped and the output voltage value.