Fixed-Ratio Bus Converter Start-Up Control for In-Rush Current
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Solution Overview
Problem
Fixed-ratio power converters face challenges in controlling in-rush current during start-up, which can exceed the current carrying capacity of switching elements and lead to system instability, especially when loads present time-varying current demands.
Innovation Solution
The implementation of a bus converter with a switch controller that operates power switching elements in high resistance during start-up to limit in-rush current and transitions to low resistance in steady-state operation, using a control circuit to manage the switch drive level and enable/disable loads accordingly, thereby controlling the equivalent series resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power switching elements are turned on in a low resistance state during start-up, then efficient power delivery is achieved, but in-rush current exceeds the current carrying capacity of switching elements
Solution Approach 1:
The patent applies dynamics by transitioning the power switching elements from a high resistance state during start-up to a low resistance state during steady-state operation. This dynamic adjustment of resistance allows the system to limit in-rush current initially while maintaining efficient power delivery once the system is stabilized, directly resolving the contradiction between power efficiency and switching element protection.
2Loss of energy
If the equivalent series resistance is decreased for efficient power delivery, then power transfer efficiency improves, but in-rush current during start-up increases beyond safe limits
Solution Approach 1:
The patent applies preliminary action by enabling the load gradually during start-up rather than immediately. The control circuit monitors system conditions and only enables the load once the system reaches steady-state operation, preventing in-rush current from exceeding safe limits while ensuring efficient power delivery is achieved once the load is enabled.
3Productivity
If the load is enabled immediately during start-up, then full power delivery is achieved, but system instability occurs due to excessive in-rush current
Solution Approach 1:
The patent applies feedback by using the control circuit to monitor system conditions during start-up and steady-state operation. The control circuit determines when to enable or disable the load based on real-time system state, providing feedback control that maintains system stability while ultimately achieving full power delivery capability once steady-state conditions are met.
Data Source
AI summary
A power converter system converts power from an input source for delivery to an active load. An input current surge at startup may be reduced by combining power converter switch resistance modulation with active load control. In another aspect, an input current surge at startup in an array of power converters may be reduced by periodically reconfiguring the array during the startup phase to accumulatively increase the output voltage up to a predetermined output voltage. A power converter may include a controller that provides an over-current signal to the load to reduce the load or advise of potential voltage perturbations.