Power Supply Module Soft Start Circuit for Inrush Current Protection
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Solution Overview
Problem
Existing power supply modules experience a big inrush current when hot plugged rapidly, which can damage the capacitor between the two DC buses and the connection terminal connecting the power supply module to the power supply system.
Innovation Solution
A power supply module with a current limiting circuit connected in a DC bus and a first capacitor between the two DC buses, along with a trigger drive circuit and an input detection circuit that outputs a notification signal to wait for a predetermined duration before sending a drive signal to the current limiting circuit, limiting the current only when necessary to avoid inrush.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current limiting resistor is connected in parallel with a switch device into the DC bus to limit inrush current, then the capacitor and connection terminal are protected from damage, but the device complexity increases
Solution Approach 1:
The patent extracts the current limiting function from a permanent circuit component and implements it temporarily through a controlled switch device. The switch device is connected in parallel with the DC bus and only activated when inrush current detection is needed, allowing current limiting without permanently adding complex circuitry to the DC bus structure.
Solution Approach 2:
The patent implements preliminary detection of inrush current conditions before the actual current flow occurs. The control device detects voltage changes across the DC bus that indicate impending inrush current, and activates the switch device in advance to prevent the harmful current from occurring, rather than reacting after damage has begun.
2Reliability
If a mechanical lock with long and short pins is used to realize soft start, then the capacitor is protected during hot plugging, but the ease of operation decreases and skill requirement increases
Solution Approach 1:
The patent replaces the mechanical lock system with an electrical control system. Instead of using physical pins of different lengths to control connection timing, the system uses voltage detection and electronic switching to control when current flows to the capacitor. This eliminates the need for mechanical complexity and specialized operator skills while maintaining protection functionality.
Solution Approach 2:
The system implements self-service through automatic detection and control. The control device continuously monitors the DC bus voltage and automatically activates the switch device when inrush conditions are detected, without requiring operator intervention or specialized knowledge of the plugging sequence. The system protects itself against inrush current automatically.
3Productivity
If the power supply module is hot plugged rapidly into the power supply system, then the productivity increases, but the inrush current damages the capacitor and connection terminal
Solution Approach 1:
The patent implements dynamic control of the current path based on real-time conditions. The switch device is controlled dynamically - open during normal operation, closed only when inrush current is detected. This dynamic switching allows rapid hot plugging to proceed at full speed while providing protection only when and where needed, rather than permanently limiting current flow.
Solution Approach 2:
The switch device acts as an intermediary between the DC bus and the capacitor. When rapidly hot-plugged, the switch device temporarily intercepts the inrush current and redirects it through the parallel path, protecting the capacitor and connection terminal. Once the capacitor is charged and the inrush condition passes, the switch device opens to restore normal direct connection, maintaining both protection and performance.
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 prevents big current shocks during rapid hot plugging, protecting the capacitor and connection terminal by controlling the current flow, thus ensuring safe and reliable operation of the power supply module.
Implementation Method 1
a current limiting circuit (52) connected in a DC bus (51)... limiting the current only when necessary to avoid inrush
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5B
AI summary
Embodiments of the present invention provide a power supply module and a soft start method. The power supply module includes an input detection circuit (53) configured to output a first notification signal to a trigger drive circuit (54) when it is determined that the power supply module receives a power supply signal; the trigger drive circuit configured to, upon receipt of the first notification signal sent from the input detection circuit, wait for a predetermined duration without sending a drive signal to a current limiting circuit (52), and to send the driver signal to the current limiting circuit (52) when the predetermined duration elapses; and the current limiting circuit configured to limit a current on a Direct Current (DC) bus (51) of the power supply module when the drive signal is not received by the current limiting circuit, and not to limit the current on the DC bus upon receipt of the drive signal.