Parallel DC Power Supply Control for Stable Current Sharing
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Solution Overview
Problem
Existing power supply networks face issues with current-sharing accuracy, dynamic performance, and complexity in parallel-connected Switching Mode Power Supply (SMPS) units, particularly in types 1, 2, and 3, which affect voltage regulation, noise immunity, and modularity, and existing droop control methods are complex and sensitive to bandwidth.
Innovation Solution
A virtual-model based control scheme for power supply networks using a virtual power source equivalent model that emulates a DC Thévenin equivalent model with a DC current source, allowing for precise current sharing through a composite voltage-current controller, ensuring equal or proportional current sharing without active communication between units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parallel-connected SMPS units are used to increase power capacity, then power supply reliability and capacity are improved, but current-sharing accuracy deteriorates
Solution Approach 1:
The patent introduces a current-sharing controller as an intermediary device that receives current signals from each SMPS unit, processes them through operational amplifiers and resistors, and generates correction signals. This mediator enables accurate current sharing by actively compensating for deviations without requiring complex modifications to each individual SMPS unit, thus maintaining reliability while improving current-sharing accuracy.
2Ease of operation
If traditional droop control methods are used for current sharing, then current sharing capability is improved, but system complexity and bandwidth sensitivity increase
Solution Approach 1:
The patent implements a feedback mechanism where current-sharing controllers continuously monitor the output current of each SMPS unit through sensing resistors, compare the signals using operational amplifiers, and adjust the duty cycle of each unit accordingly. This closed-loop feedback system achieves accurate current sharing while maintaining simple circuit implementation that is not sensitive to bandwidth variations, resolving the contradiction between current sharing capability and system complexity.
3Stability of the object's composition
If voltage regulation is prioritized in SMPS units, then output stability is improved, but dynamic response performance deteriorates
Solution Approach 1:
The patent employs dynamic current-sharing control where the controllers continuously adjust the operating point of each SMPS unit based on real-time current measurements. By dynamically modifying the duty cycle through PWM control in response to load changes, the system maintains voltage stability while achieving fast dynamic response, as the active current-sharing mechanism allows rapid adaptation to changing conditions without compromising output stability.
Data Source
AI summary
In certain aspects, a power supply unit includes a direct current (DC) power supply circuit and a regulation control circuit coupled to the DC power supply circuit. The DC power supply circuit is configured to provide an output voltage and an output current at an output port. The regulation control circuit is configured to generate a regulation control signal based at least in part on a measured voltage value of the output voltage and a measured current value of the output current at the output port. The DC power supply circuit is further configured to, based on the regulation control signal, regulate at least one of the output voltage to have a target voltage value or the output current to have a target current value.