Inrush Current Limiting Power Supply with Supervisor Circuit
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Solution Overview
Problem
Low-power power supplies connected to earth ground are unsafe due to high inrush currents, which can cause injuries or trip circuit breakers, and existing solutions like current limiter circuits can lead to fault states during voltage dips.
Innovation Solution
A low-power universal input power supply system that includes an AC input circuit, a current limiter circuit, a switched-mode power supply, a supervisor circuit, and a relay control circuit to regulate voltage rails and limit inrush currents, ensuring safe operation by connecting or disconnecting the load based on voltage thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power supply is connected to earth ground for return, then it can provide power to external loads, but high inrush current occurs that can cause injuries or trip circuit breakers
Solution Approach 1:
The supervisor circuit is enabled in advance before the relay control circuit, allowing it to monitor voltage conditions and prepare the system for safe operation. The circuit progressively enables different voltage rails (first 5V rail, then 12V rail) in a controlled sequence, preventing simultaneous power-up that would cause inrush current spikes.
Solution Approach 2:
The power supply uses a staged, periodic enabling sequence where different voltage rails are activated at different times based on supervisor circuit monitoring. The system transitions through distinct operational phases: initial supervisor enablement, first voltage rail activation, second voltage rail activation, and final relay control, with each phase completing before the next begins.
2Object-generated harmful factors
If a current limiter circuit is used to limit inrush current, then safety is improved, but the circuit may enter fault states during voltage dips
Solution Approach 1:
The supervisor circuit acts as an intermediary between the voltage rails and the relay control circuit, monitoring voltage conditions and controlling the enabling sequence. This intermediary layer prevents direct connection of loads during voltage dips, allowing the current limiter to operate safely without entering fault states, as the supervisor ensures voltage stability before enabling power delivery.
3Productivity
If voltage rails are enabled simultaneously, then power delivery is fast, but inrush current exceeds safe levels
Solution Approach 1:
The supervisor circuit is enabled in advance to establish voltage monitoring before any voltage rails are activated. This preliminary setup allows the system to quickly detect voltage conditions and proceed with sequential rail enabling, minimizing total power-up time while preventing inrush current through controlled staging of the voltage rails.
4Productivity
If the relay control circuit is enabled immediately, then load connection is fast, but safety risks increase due to unmonitored voltage conditions
Solution Approach 1:
The supervisor circuit is enabled in advance to establish voltage monitoring and control before the relay control circuit becomes active. This preliminary supervision ensures that when the relay control circuit is eventually enabled, voltage conditions are already monitored and controlled, allowing fast load connection with maintained safety through the established supervision framework.
Data Source
AI summary
A system for providing power from an AC power supply to an external load. The system includes a current limiter circuit, connected to an input of a switched-mode power supply. The system includes the switched-mode power supply that provides a first voltage signal and a second voltage signal. The system includes a supervisor circuit that is connected to the first output of the switched-mode power supply and coupled to a relay control circuit. The supervisor circuit monitors the first voltage signal and enables the relay control circuit. The relay control circuit provides a first voltage corresponding to the first voltage signal to a first voltage rail and provides a second voltage corresponding to the second voltage signal to a second voltage rail. A relay powered by a connection to the first voltage rail or the second voltage rail connects the AC power supply to an external load.