Dual Function Inrush Limiting Circuit for DC-DC Converters
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Solution Overview
Problem
Conventional inrush limiting circuits for DC-DC converters are bulky, costly, and exhibit long startup delay times, requiring additional circuitry for input voltage surges, which can stress other circuits and EMI filter components.
Innovation Solution
A dual-function inrush limiting circuit using a level shift circuit with a Zener diode, block diode, and capacitor, along with a switch and photovoltaic coupler, to rapidly limit input current and output voltage, reducing component count and startup delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional inrush limiting circuits use passive approach with inductor or bypass-resistor/switch, then inrush current is limited, but the circuit becomes bulky and heavier
Solution Approach 1:
The patent replaces passive mechanical inductors and large relay-based switches with an active controlled current circuit using a current source, MOSFET switch, and RC timing circuit. This substitution eliminates the need for bulky passive components while achieving the same inrush limiting function through active electronic control.
2Reliability
If conventional inrush limiting circuits use large relays, then inrush current is limited, but startup delay time increases
Solution Approach 1:
The patent uses a dynamically controlled MOSFET switch instead of a mechanical relay, allowing for faster switching response. The RC timing circuit (R1, C1) provides programmable delay control, enabling the system to adapt the startup timing precisely without the inherent mechanical delay of relay-based systems.
3Stability of the object's composition
If conventional inrush limiting circuits are used, then power line stability is improved, but additional circuitry is required for input voltage surges
Solution Approach 1:
The patent designs the active controlled current circuit to perform multiple functions: it limits inrush current during startup, regulates input voltage during operation, and protects against voltage surges. The same current source and switching circuitry handle all these functions, eliminating the need for separate protection circuits and reducing overall system complexity.
4Reliability
If conventional inrush limiting circuits are used, then inrush current is limited, but cost and weight increase due to large transient voltage suppressors
Solution Approach 1:
The patent uses inexpensive, small-signal electronic components (resistors, capacitors, diodes, MOSFET) to replace expensive large-signal transient voltage suppressors. The active controlled current circuit achieves surge protection functionality using low-cost components that can be easily manufactured and replaced if needed.
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
The solution provides a lightweight, compact, and cost-effective inrush limiting circuit that quickly activates to manage inrush currents and voltage surges, preventing damage to other circuits and EMI filter components while ensuring reliable power delivery.
Implementation Method 1
The level shift circuit may include a Zener diode, a block diode and a capacitor. The Zener diode being in anti-series with respect to the block diode.
Implementation Method 2
The level shift circuit may include a Zener diode, a block diode and a capacitor. The Zener diode being in anti-series with respect to the block diode.
Implementation Method 3
The level shift circuit may include a Zener diode, a block diode and a capacitor. The capacitor of the LSC is configured to adjust an activation time of the switch.
Implementation Method 4
a photovoltaic coupler configured to adjust a voltage at the output terminal when a voltage at the reference voltage input is above a predetermined threshold
Data Source
AI summary
Systems and methods are provided for a dual function inrush limiting circuit (ILC). The systems and methods may include a level shift circuit (LSC). The LSC may include a Zener diode, a block diode and a capacitor. The Zener diode being in anti-series with respect to the block diode. The ILC may further include a switch electrically coupled to the LSC, an input terminal and an output terminal. The LSC may be configured to activate the switch such to electrically couple the input terminal to the output terminal. The ILC may include a direct current (DC)-DC converter electrically coupled to the output terminal. The DC-DC converter being electrically coupled to the input terminal when the switch is activated.