Parallel DC Source Current-Sharing Circuit Without Full-Power Converters
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Solution Overview
Problem
Existing technologies for controlling the current of DC voltage sources in parallel configurations, such as in battery energy storage and photovoltaic systems, face challenges of increased cost and reduced efficiency due to the use of full-power DC/DC converters, which lead to energy loss and high costs.
Innovation Solution
A circuit and control method that utilizes a low-voltage DC bus capacitor, power electronics half-bridge units, branch circuit inductors, and DC switches to form current-sharing branch circuits, allowing precise current control through pulse-width modulation, thereby eliminating the need for full-power DC/DC converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full-power DC/DC converters are used to control current of DC voltage sources in parallel, then current control performance is improved, but system cost and energy loss increase
Solution Approach 1:
The patent divides the full-power DC/DC converter into separate functional modules: current-sharing control modules for each parallel branch and a central control module. Each branch only needs partial power conversion capability rather than full-power conversion, reducing overall system power rating and energy losses while maintaining current control precision through distributed control architecture
Solution Approach 2:
The patent implements partial power conversion by using current-sharing control where each branch converter only needs to handle its portion of the total power rather than full-power conversion. The current-sharing control mechanism ensures that partial conversion actions in each branch collectively achieve the desired overall current control performance
2Measurement precision
If full-power DC/DC converters are used to control current of DC voltage sources in parallel, then current control performance is improved, but system cost increases
Solution Approach 1:
The patent segments the expensive full-power DC/DC converter into multiple lower-cost partial-power conversion modules with distributed current-sharing control. Each module is simpler and less expensive, but their coordinated operation through current-sharing control achieves the same current control precision as a single full-power converter
Solution Approach 2:
The patent uses identical current-sharing control modules replicated across multiple parallel branches. This modular copying approach reduces system cost by using standardized, simpler modules rather than a complex full-power converter, while maintaining current control precision through identical control logic in each branch
3Reliability
If externally powered isolated DC power supplies are used to compensate output voltage, then voltage compensation is achieved, but system cost increases
Solution Approach 1:
The patent enables the DC voltage sources themselves to perform voltage compensation through the current-sharing control mechanism. Instead of requiring external power supplies, the system uses the DC voltage sources' own power capability, controlled through current-sharing logic, to compensate for voltage variations. This self-service approach eliminates external power supplies and reduces system cost
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 solution reduces system size and cost while improving efficiency by converting DC voltage sources into current sources, achieving precise current control and eliminating the need for external power supplies.
Implementation Method 1
controlling the current of DC voltage sources in parallel through current-sharing control without requiring full-power DC/DC converters
Implementation Method 2
an output neutral point of each power electronics half-bridge unit is connected in series with one of the first set of branch circuit inductors
Data Source
AI summary
A circuit for controlling a DC voltage source current includes a low-voltage DC bus capacitor, a first set of power electronics half-bridge units, a first set of branch circuit inductors, and a first set of DC switches. All of the first set of power electronics half-bridge units are connected in parallel between a positive pole and a negative pole of a low-voltage DC bus and are also connected in parallel with the low-voltage DC bus capacitor, an output neutral point of each power electronics half-bridge unit is connected in series with one of the first set of branch circuit inductors and one of the first set of DC switches to form one of a first set of current-sharing branch circuits, and each power electronics half-bridge unit and the corresponding current-sharing branch circuit are used to be connected with a DC voltage source to form a DC voltage source branch circuit.