Boost Converter Protection Circuit for Inrush Current Control
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Solution Overview
Problem
Conventional boost converters are prone to damage from short circuits and open circuits during startup, leading to inrush currents and potential component damage, particularly affecting the inductor, diode, and power switch.
Innovation Solution
A protection apparatus is introduced, comprising a fault protection circuit, over-voltage protection circuit, over-current protection circuit, detectors, a current source, and a timer, which monitor and control the load disconnect switch to prevent damage by managing inrush currents and detecting faults such as short circuits and open circuits, thereby reducing or eliminating inrush currents and protecting components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the load disconnect switch is turned on immediately at startup, then the converter can start up quickly, but a large inrush current is produced that damages components
Solution Approach 1:
The patent applies preliminary action by pre-charging the switching node through a current source before turning on the load disconnect switch. This preliminary charging action raises the switching node voltage to near input voltage level, eliminating the voltage difference that would otherwise cause inrush current when the switch closes, thus enabling fast startup without component damage
Solution Approach 2:
The patent applies preliminary anti-action by using a current source to pre-charge the switching node, which counteracts the potential inrush current before it can occur. The pre-charge current creates a opposing effect that prevents the harmful inrush current from damaging the inductor and other components during startup
2Device complexity
If the boost converter operates without protection circuits, then the device complexity is reduced, but short circuits and open circuits can damage components
Solution Approach 1:
The patent applies feedback by using detectors to continuously monitor the switching node voltage and feedback voltage, and using this information to control the load disconnect switch and protection circuits. The feedback mechanism enables automatic detection and response to fault conditions such as short circuits and open circuits, protecting components without requiring complex external protection circuits
Solution Approach 2:
The patent applies multi-functionality by integrating multiple protection functions (over-voltage protection, over-current protection, short-circuit protection, open-circuit protection) into a single protection apparatus that works with the existing boost converter components. The fault protection circuit serves multiple purposes: controlling the load disconnect switch, activating protection circuits, and coordinating with detectors and timers to handle various fault conditions
3Reliability
If detectors and protection circuits are added, then component protection is improved, but the device complexity increases
Solution Approach 1:
The patent applies merging by combining multiple protection functions and control operations into a single fault protection circuit. The fault protection circuit integrates the control of the load disconnect switch, activation of over-voltage and over-current protection circuits, and coordination with detectors and timers, reducing the need for separate complex protection circuits for each function
Data Source
AI summary
A boost converter includes a load disconnect switch connected between a voltage input terminal and an inductor, a power switch connected to the inductor by a switching node, a diode connected between the switching node and a voltage output terminal, and an output capacitor connected to the voltage output terminal to provide an output voltage. A protection apparatus is connected to the load disconnect switch, switching node and power switch to monitor the voltage at the switching node and the output voltage to provide open circuit and short circuit protection for the boost converter.