DC/DC Converter Droop Control for Stable DC Link Voltage
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Solution Overview
Problem
Existing droop control methods in energy storage systems result in fixed operating points for DC/DC converters, leading to non-responsive sections when voltage drops or rises, and limitations in charging, discharging, or idle operations based on voltage sections, causing instability in DC link voltage.
Innovation Solution
A power conversion device with an input unit, power conversion unit, output unit, and control unit that adjusts reference voltage based on DC link voltage differences, enabling droop control and stable operation by charging or discharging batteries, and limiting power within predetermined ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fixed droop control is used with predetermined charge/discharge voltage sections, then the control method is simple, but the DC link voltage becomes unstable and non-responsive sections occur when voltage drops or rises
Solution Approach 1:
The patent applies dynamics by making the operating point of the DC/DC converter variable rather than fixed. The converter's operating point is allowed to move dynamically along the droop curve based on real-time DC link voltage conditions, enabling the system to respond flexibly to voltage changes and maintain stability while preserving the simplicity of the droop control approach.
Solution Approach 2:
The patent changes the parameter of the converter's operating point from fixed to variable. By allowing the operating point to change along the droop curve based on DC link voltage, the system achieves better voltage stability and responsiveness without complicating the control methodology.
2Device complexity
If the operating point of DC/DC converter is fixed along the droop curve, then the control is simple, but the power output is fixed to 0 in idle section causing non-responsive section when voltage drops or rises
Solution Approach 1:
The patent makes the converter's operating point dynamic along the droop curve, allowing it to adjust its position based on DC link voltage conditions. This enables the system to exit idle sections and respond to voltage drops or rises while maintaining relatively simple droop control logic.
Solution Approach 2:
The patent implements feedback by continuously monitoring the DC link voltage and using this information to adjust the converter's operating point along the droop curve. This feedback mechanism enables the system to detect voltage changes and respond appropriately, improving adaptability without significantly increasing control complexity.
3Ease of operation
If charge and discharge operations are restricted to specific voltage sections, then the control logic is simplified, but charging and discharging become impossible in certain voltage sections reducing system flexibility
Solution Approach 1:
The patent applies universality by enabling the DC/DC converter to perform multiple functions (charging, discharging, and idle operation) across all voltage sections of the droop curve. The converter can operate in any section depending on system needs, making the control logic universally applicable throughout the entire operating range rather than requiring separate logic for each voltage section.
Data Source
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AI summary
A power conversion device according to one embodiment of the present invention comprises: an input unit which is connected to a DC link end, and which receives voltage and current of the DC link end; a power conversion unit for converting the voltage of the DC link end; an output unit for outputting the converted voltage; and a control unit, which compares the voltage of the DC link end to a reference voltage, uses the difference between the voltage of the DC link end the reference voltage so as to control the power conversion unit, and uses the current of the DC link end according to operation of the power conversion unit so as to adjust the reference voltage.