Virtual Impedance Tracking for Balanced Multi-PSU Current Sharing
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Solution Overview
Problem
In multi-PSU systems, unequal output voltages due to varied impedance lead to inefficient current sharing, with one PSU often exceeding its capacity and shutting down, and existing current-sharing methods like active and passive modes fail to achieve balanced current distribution effectively.
Innovation Solution
A method involving real and virtual impedance calculation to adjust power generation in each PSU, using local and remote voltage measurements to determine a virtual impedance value, allowing for equal current sharing among multiple PSUs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active current-sharing mode is used with master-slave relationship, then current balance can be achieved, but adjustment speed is slow and efficiency is poor
Solution Approach 1:
The patent implements a feedback mechanism where each PSU measures its own output current and compares it with the average current of all PSUs. Based on this feedback, each PSU independently adjusts its output voltage to achieve current balance. This eliminates the slow master-slave information sharing process and enables faster concurrent adjustment across all PSUs.
Solution Approach 2:
Each PSU independently determines its own output voltage adjustment based on its measured current and the calculated average current. The PSUs self-regulate without requiring external control or waiting for master PSU instructions, enabling parallel adjustment and improving overall system response speed and efficiency.
2Productivity
If passive current-sharing mode is used with independent control, then adjustment speed is fast, but current equilibrium cannot be achieved due to impedance divergence
Solution Approach 1:
Each PSU continuously monitors its output current and compares it with the average current feedback from all PSUs. This feedback loop enables each PSU to detect current imbalances and adjust its output voltage accordingly, ensuring current equilibrium is achieved while maintaining fast adjustment speed through independent concurrent control.
Solution Approach 2:
The patent dynamically adjusts the output voltage parameter of each PSU based on real-time current measurements and the calculated average current. By changing the voltage parameter in response to current deviations, each PSU can rapidly adapt to maintain current equilibrium despite impedance variations among different PSUs.
3Device complexity
If no current-sharing control is used, then system complexity is low, but one PSU will overload and shut down
Solution Approach 1:
Each PSU independently measures its own output current, calculates the average current from all PSUs, and autonomously adjusts its output voltage to maintain current balance. This self-service approach distributes the control function across all PSUs, avoiding the need for complex centralized control while preventing any single PSU from overloading and shutting down.
Data Source
AI summary
Current sharing in a power system having multiple PSUs comprises generating and supplying a first power and a second power to a load, and sensing a remote voltage value received by the load based on an accumulation of the first and second powers. The method further comprises determining, by the first PSU, local voltage and current values of the first power, a real impedance value of the first PSU based on the remote voltage value and the local voltage and current values of the first power, and a virtual impedance value of the first PSU based on the real impedance value of the first PSU and a reference impedance value. The method further comprises controlling generation of the first power by the first PSU based on the virtual impedance value of the first PSU.