Inrush Current Limitation Circuit for Power Supplies
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Solution Overview
Problem
Information handling systems face issues with inrush current overload, which can trigger overcurrent protection and cause unexpected failures due to the high current surges when power is restored after a disruption, especially with longer hold-up times, leading to potential damage to components like fuses and diodes.
Innovation Solution
A method and circuit for a power supply unit (PSU) that detects inrush current thresholds and fully turns off a series transistor to block the current, transferring magnetic energy stored in a boost choke to a bulk capacitor, and then immediately turns it back on after the energy transfer, effectively managing inrush currents and preventing component damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a longer hold-up time is designed to provide stable power during disruptions, then the power supply stability is improved, but the inrush current increases and can trigger overcurrent protection
Solution Approach 1:
The control circuit preemptively detects when the bulk capacitor charge drops below a threshold during normal operation, and proactively controls the series transistor to limit inrush current before the power disruption occurs. This preliminary action prevents the harmful inrush current from occurring in the first place, resolving the contradiction between long hold-up time and inrush current prevention.
Solution Approach 2:
The control circuit continuously monitors the charge level of the bulk capacitor and provides feedback control to the series transistor. When the charge drops below a threshold, the control circuit adjusts the transistor's conduction state to limit inrush current, creating a closed-loop feedback system that dynamically balances hold-up time requirements with inrush current prevention.
2Object-affected harmful factors
If a resistor or temperature-sensitive device is added to limit initial inrush current, then the initial inrush current is reduced, but the circuit complexity increases due to additional bypass devices
Solution Approach 1:
The series transistor serves multiple functions: it limits initial inrush current, limits resumed inrush current after power disruptions, and provides feedback-controlled regulation. This single component performs the work of multiple traditional components (resistor, PTC/NTC device, relay), reducing overall circuit complexity while maintaining comprehensive inrush current protection.
Solution Approach 2:
The control circuit uses the existing bulk capacitor charge level information to automatically regulate the series transistor, making the system self-regulating without requiring external temperature-sensitive devices or complex bypass circuits. The system serves itself by using its own operational parameters (capacitor charge level) to control its own inrush current.
3Loss of energy
If a relay is used to bypass the temperature-sensitive device during normal operation, then the power loss through the device is reduced, but the circuit becomes unprepared to respond to resumed inrush current
Solution Approach 1:
The control circuit continuously monitors bulk capacitor charge level and provides feedback control to the series transistor, ensuring the transistor remains active and ready to respond to resumed inrush current conditions. This feedback mechanism eliminates the need for relays to bypass components, as the system dynamically adjusts the transistor's state based on real-time capacitor charge information, maintaining both energy efficiency and reliability.
Solution Approach 2:
The control circuit preemptively detects when capacitor charge drops below a threshold and proactively adjusts the series transistor's conduction state before power disruptions occur. This preliminary action ensures the circuit is always prepared to handle resumed inrush current, eliminating the reliability issues associated with relay-based bypass systems that leave the circuit unprepared during normal operation.
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
This solution effectively limits inrush currents, preventing component damage and ensuring stable operation by rapidly transferring magnetic energy to the bulk capacitor, thereby reducing the risk of overcurrent events and maintaining system uptime.
Implementation Method 1
transferring magnetic energy stored in a boost choke to a bulk capacitor
Data Source
AI summary
A method and circuit for a power supply unit (PSU) suitable for use in an information handling system to detect an inrush current reaching an inrush current threshold, to fully turning off, by a control circuit of the PSU, a series transistor to block the inrush current, to transfer, while the series transistor is fully turned off, magnetic energy stored in a boost choke to a bulk capacitor, and to fully turn on, by the control circuit of the PSU, the series transistor again immediately after the series transistor was in a fully turned off state, wherein the fully turning on occurs after the magnetic energy stored in the boost choke has been transferred to the bulk capacitor.