Fixed-Ratio Bus Converter Start-Up Control for In-Rush Current
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Solution Overview
Problem
Existing power systems with fixed-ratio converters face challenges in managing in-rush currents during start-up, which can exceed the current carrying capacity of switching elements and lead to inefficiencies and potential system disruptions, 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 currents and transitions to low resistance in steady-state operation, using a control circuit to disable loads during start-up and enable them during steady-state, thereby managing equivalent series resistance and reducing peak currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If power switching elements are turned ON in a low resistance state during start-up, then power delivery efficiency is improved, but in-rush current exceeds current carrying capacity and causes system disruptions
Solution Approach 1:
The equivalent series resistance of the bus converter is dynamically adjusted based on operating phase: during start-up, the power switching elements are operated in a high resistance state to limit in-rush current, and during steady-state, they transition to a low resistance state for efficient power delivery. This dynamic resistance adjustment resolves the contradiction between limiting start-up currents and maintaining efficient power delivery.
Solution Approach 2:
The control circuit disables the load during the start-up phase before enabling it during steady-state operation. This preliminary disabling of the load prevents excessive in-rush current from damaging the power switching elements while still allowing the system to build up voltage and stabilize before full power delivery begins.
2Reliability
If power switching elements are operated in a high resistance state during start-up, then in-rush current is limited, but power delivery efficiency decreases
Solution Approach 1:
The power switching elements dynamically transition between high resistance state during start-up and low resistance state during steady-state operation. This dynamic operation allows the system to prioritize reliability during start-up while maximizing efficiency during normal operation, resolving the contradiction between current limiting and power delivery efficiency.
Solution Approach 2:
The bus converter operates in distinct periodic phases: a start-up phase with high resistance for current limiting, followed by a steady-state phase with low resistance for efficient power delivery. This periodic switching between operational modes allows the system to address both reliability and efficiency requirements at appropriate times.
3Productivity
If the load is enabled during start-up phase, then power delivery begins immediately, but peak currents disrupt system operation
Solution Approach 1:
The control circuit disables the load during start-up and enables it only during steady-state operation. This preliminary action sequence ensures that the power conversion infrastructure is fully established and stable before the load begins drawing power, preventing current disruptions while still achieving reliable power delivery.
Solution Approach 2:
The load enable state is dynamically controlled based on the operating phase: disabled during start-up to prevent in-rush current issues, and enabled during steady-state for full power delivery. This dynamic control resolves the contradiction between immediate power delivery and system stability.
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 approach effectively controls in-rush currents, reduces switching losses, and maintains efficient power delivery by adjusting the switch drive level based on input current limits, ensuring stable operation and minimizing the impact of start-up surges on the power system.
Implementation Method 1
The bus converter may turn the power switching elements ON in a high resistance state in the start-up phase to increase the equivalent series resistance and in a low resistance state in the steady-state phase to decrease the equivalent series resistance
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.