Parallel Power Supply Droop Control for Reverse Current Isolation
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Solution Overview
Problem
Existing power supply systems with redundant configurations face reliability issues due to voltage drops when one power supply apparatus experiences a short-circuit failure.
Innovation Solution
A power supply system comprising at least two power supply apparatuses, each equipped with a converter, a FET, a current detector, a droop characteristic controller, and a reverse current limitation unit, which controls the output voltage to droop at a specific rate based on load current and limits reverse current to enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the outputs of two power supply apparatuses are directly combined in a redundant configuration, then the power supply system can provide redundancy, but if one power supply apparatus suffers a short-circuit failure, the voltage supplied to the load might lower
Solution Approach 1:
An ORing element is introduced as an intermediary component between the power supply apparatuses and the load. This ORing element selectively connects the load to the functioning power supply apparatus, preventing the failed apparatus with short-circuit from affecting the output voltage. The intermediary isolates the fault while maintaining power supply to the load.
Solution Approach 2:
The control circuit extracts and monitors the output voltage of each power supply apparatus separately. When a short-circuit failure is detected, the control circuit removes the failed apparatus from the parallel connection by controlling the ORing element, thereby preventing it from dragging down the overall output voltage supplied to the load.
2Reliability
If a power supply apparatus operates in parallel with other power supplies, then redundancy is achieved, but reverse current flowing from the load towards the converter may cause chain-reaction suspension of other operating power supply apparatuses
Solution Approach 1:
The ORing element acts as a one-way valve that allows current to flow from the power supply apparatus to the load but blocks reverse current from flowing back from the load to the converter. This intermediary prevents reverse current from propagating through the parallel-connected power supply apparatuses and causing chain-reaction failures.
Solution Approach 2:
The circuit design anticipates the harmful effect of reverse current and converts it into a protective mechanism. By detecting reverse current flow and automatically isolating the affected apparatus through the ORing element, the system transforms the potential harm into a protective action that prevents chain-reaction failures.
Data Source
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AI summary
A power supply system includes at least two power supply apparatuses (10) that supply current to one load. Each power supply apparatus includes a converter (20) that supplies current to the load, a FET (40) connected in series between the converter and the load, a current detection unit (30) that detects current flowing between the converter and the load, and a droop characteristic controller that causes output voltage of the converter to droop at a droop rate determined based on the magnitude of load current flowing from the converter towards the load. The droop rate is greater when the load current is included in a first current section than when the load current is included in each of a second current section and a third current section. The second current section includes smaller current than the first current section. The third current section includes larger current than the first current section.