Hybrid Sigma Converter Startup Control for Inrush-Limited ISOP Power
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Solution Overview
Problem
Existing power converters for data centers require additional space and components like eFuses for startup, leading to inefficiencies and potential destructive inrush currents, especially in ISOP converters with unregulated sub-converters.
Innovation Solution
A hybrid sigma converter with a control circuit that manages the switching frequencies and duty cycles of unregulated and regulated sub-converters to avoid inrush currents, eliminating the need for eFuses and enabling efficient startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an eFuse is used for startup of ISOP converters with unregulated sub-converters, then the startup process can be controlled, but additional space and components are required
Solution Approach 1:
The patent extracts the startup control function from a dedicated eFuse controller and implements it within the existing control circuitry of the regulated sub-converter. The control circuit is modified to detect startup conditions and automatically adjust switching parameters, eliminating the need for separate eFuse controller hardware and reducing overall device footprint.
Solution Approach 2:
The control circuit of the regulated sub-converter is designed to perform multiple functions: normal voltage regulation during operation and startup control when the unregulated sub-converter is initially powered. This multi-functionality allows the same circuit to handle both startup sequencing and ongoing regulation without requiring additional dedicated startup components.
2Productivity
If the input voltage is ramped up while sub-converters are switching during startup, then the startup process can proceed, but destructive inrush currents may occur
Solution Approach 1:
The control circuit detects startup conditions before full power operation begins and preemptively adjusts the switching frequency and duty cycle of the regulated sub-converter. By preparing the circuit in advance with reduced switching activity, the system prevents inrush currents from occurring when voltage is applied, allowing safe and relatively rapid startup.
Solution Approach 2:
The switching frequency and duty cycle of the regulated sub-converter are made dynamic during startup rather than fixed. The control circuit continuously adjusts these parameters based on the detected startup state, initially using lower frequencies and duty cycles to limit inrush current, then transitioning to normal operating parameters once startup is complete.
3Reliability
If oversized components are used to handle startup currents, then reliability during startup is improved, but device density is reduced
Solution Approach 1:
The patent changes the operational parameters (switching frequency and duty cycle) of the regulated sub-converter during startup rather than relying on oversized hardware components. By dynamically adjusting these electrical parameters, the system achieves reliable startup current control using the same physical components, thereby maintaining high device density without compromising startup reliability.
Data Source
AI summary
A power converter circuit, including: an unregulated sub-converter; a regulated sub-converter connected to the unregulated sub-converter, wherein the power converter circuit is configured as an input-series-output-parallel (ISOP) non-isolated power converter circuit; and a control circuit operable, during a startup of the power converter circuit, to: control the unregulated sub-converter with a transition from an initial unregulated duty cycle to a nominal unregulated duty cycle, which is higher than the initial unregulated duty cycle; and control the regulated sub-converter with a transition from an initial regulated duty cycle to a nominal regulated duty cycle to maintain an output voltage of the power converter circuit to be lower than a nominal output voltage.