Staggered Power Switching for SMPS Inrush Current Control
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Solution Overview
Problem
The initial startup current surge in electronic devices powered by switched-mode power supplies (SMPS) causes undesirable power spikes and can lead to nuisance tripping of circuit breakers, and LED display screens consume significant power even when seemingly turned off, resulting in unnecessary energy consumption.
Innovation Solution
A power switching system with multiple power switching modules that introduce time delays of varying and independent durations to manage the startup current, allowing each module to switch on power at different times, thereby minimizing the maximum startup current and enabling efficient power control, including the ability to keep the main power source on while switching individual modules off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple SMPS-powered devices are switched on simultaneously, then power supply to all devices is provided, but combined inrush current causes nuisance tripping of circuit breakers
Solution Approach 1:
The system segments the simultaneous power-on operation into sequential operations by dividing devices into groups and assigning different time delays to each group. This segmentation of the startup process reduces the peak inrush current by preventing all devices from drawing maximum current at the same time, thereby avoiding nuisance tripping while still providing power to all devices.
Solution Approach 2:
The system performs preliminary action by pre-calculating and assigning different time delays to each device or group of devices before the actual power-on event. This preliminary timing arrangement ensures that devices start up in a controlled sequence, with the first device receiving power immediately and subsequent devices receiving power after predetermined time intervals, thus managing inrush current proactively.
2Reliability
If circuit breakers are oversized to withstand inrush currents, then nuisance tripping is prevented, but sensitivity to detect electrical faults is reduced
Solution Approach 1:
The system performs preliminary action by pre-calculating and assigning different time delays to each device or group of devices before the actual power-on event. This preliminary timing arrangement ensures that devices start up in a controlled sequence, with the first device receiving power immediately and subsequent devices receiving power after predetermined time intervals, thus managing inrush current proactively.
3Reliability
If LED display screens are kept powered on to avoid nuisance tripping, then continuous operation is ensured, but unnecessary power consumption occurs
Solution Approach 1:
The system segments the power supply control to individual devices or groups of devices, allowing selective powering on and off. This segmentation enables the LED display screen to be completely powered down when not in use, eliminating unnecessary power consumption, while the sequential startup capability ensures reliable operation when power is restored or when devices are activated.
4Object-affected harmful factors
If manual switching of discrete units is used to reduce inrush current, then power surge is controlled, but device complexity and operation difficulty increase
Solution Approach 1:
The system implements self-service by automatically managing the sequential power-on sequence without requiring manual intervention. The controller automatically assigns and enforces time delays for each device or group, performing the function that would otherwise require manual switching operations. This automation reduces both device complexity and operation difficulty while maintaining control over inrush current.
Data Source
AI summary
A power switching system for controlling power supply to an electronic assembly comprising a plurality of electronic devices each having a power supply unit, the power switching system comprising a plurality of power switching modules, each power switching module being configured to control power supply by a respective one of the power supply units to one of the electronic devices. Each power switching module comprises a module output for connecting to the power supply unit of a respective one of the electronic devices; a control input configured to receive a control signal; and a switch configured to, following receipt of the control signal, activate an electrical connection between the module output and the respective power supply unit and thereby to cause the power supply unit to switch on power supply to at least the respective one of the plurality of electronic devices.