DC-DC Converter Overvoltage Protection via Flying Capacitor Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional DC-DC converters with flying capacitors do not effectively prevent overvoltage from being applied to switching elements, which can lead to damage due to the lack of sensing and control measures for the voltage at both ends of the switching elements.
Innovation Solution
A DC-DC converter design that includes a controller to determine overvoltage by comparing sensed voltages from the flying capacitor and the output capacitor with preset reference values, controlling the switching elements to prevent excessive voltage from being applied to the switching elements, and incorporating a second capacitor connected between switching elements to manage voltage distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If a conventional flying capacitor is used to reduce inductor size and weight, then the inductor size and weight are decreased, but the switching elements are vulnerable to overvoltage damage due to lack of voltage sensing and protection
Solution Approach 1:
The controller performs preliminary overvoltage determination by comparing sensed voltages with reference values before the overvoltage can damage the switching elements. This proactive detection allows the system to take preventive action by controlling the switching elements to avoid damage, resolving the contradiction between using a flying capacitor for weight reduction and maintaining switching element reliability.
2Device complexity
If voltage sensing is implemented at capacitor terminals only, then the structure remains simple, but overvoltage conditions at switching element terminals cannot be detected
Solution Approach 1:
The controller acts as an intermediary that infers switching element terminal voltages by combining sensed capacitor voltages with knowledge of the circuit topology and switching states. This approach avoids the need for direct voltage sensing at each switching element terminal while still achieving accurate overvoltage detection, thus maintaining simple sensing structure while improving measurement precision for protection purposes.
Data Source
AI summary
A DC-DC converter includes: a first capacitor; a first switching element, a second switching element, a third switching element, and a fourth switching element sequentially connected to one another in series between both ends of the first capacitor; a second capacitor having both ends connected at a connection node of the first switching element and the second switching element and a connection node of the third switching element and the fourth switching element, respectively; and a controller configured to determine whether an overvoltage is applied to both ends of the first to fourth switching elements, respectively, based on a first sensed voltage obtained by sensing a voltage applied to the first capacitor and a second sensed voltage obtained by sensing a voltage applied to the second capacitor.