DC-DC Converter Output Capacitor Arrangement for Voltage Peak Management
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Solution Overview
Problem
Existing DC-DC converters with electrolytic capacitors in automotive electronics face excessive voltage increases due to parasitic series resistance, especially at low temperatures, which can damage components and require costly additional capacitors to mitigate this issue.
Innovation Solution
A DC-DC converter design incorporating a hybrid electrolytic capacitor, a suppressor diode, and a parallel resistance to minimize voltage increases, using a series circuit with a ceramic capacitor to manage energy feedback and reduce switching delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If electrolytic capacitors with high capacitance are used, then the ability to temporarily deliver high current is improved, but the series resistance increases greatly at low temperatures causing excessive voltage increase
Solution Approach 1:
The patent divides the capacitor function into two separate components: an electrolytic capacitor for providing high capacitance and current delivery capability, and a ceramic capacitor for providing low series resistance at low temperatures. Each capacitor type is optimized for its specific function, resolving the contradiction between high capacitance and low ESR at cold temperatures.
Solution Approach 2:
The patent creates a composite capacitor arrangement by connecting electrolytic and ceramic capacitors in parallel. This composite structure combines the advantages of both capacitor types: the electrolytic capacitor provides high capacitance while the ceramic capacitor provides low ESR, especially at low temperatures, thereby preventing excessive voltage increase.
2Stability of the object's composition
If additional ceramic capacitors are installed in parallel to reduce voltage swing, then the voltage stability is improved, but the component costs and space requirements increase
Solution Approach 1:
The patent changes the parameter combination by selecting specific capacitance values for the electrolytic capacitor (≥500 μF) and ceramic capacitor (≥2.2 μF) that provide optimal voltage stability. This parameter optimization ensures that the ceramic capacitor effectively compensates for voltage swing without requiring excessive component quantities, balancing performance with cost and space constraints.
3Adaptability or versatility
If the operating voltage is used for further electronic circuits, then the system integration is improved, but the components must be dimensioned for higher rated voltage to prevent damage
Solution Approach 1:
The patent implements beforehand cushioning by using the ceramic capacitor to prevent excessive voltage increase at the electrolytic capacitor terminals before it can reach harmful levels. This proactive voltage clamping protects downstream electronic components that share the operating voltage, enabling system integration without requiring all components to be rated for higher voltages.
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 effectively reduces voltage peaks during freewheeling phases in inductive loads, preventing component damage and reducing costs by maintaining stable voltage across electronic circuits.
Implementation Method 1
a series circuit composed of a hybrid electrolytic capacitor and a suppressor diode
Implementation Method 2
a resistance connected in parallel with the hybrid electrolytic capacitor
Implementation Method 3
additional ceramic capacitors or MLCCs (multilayer ceramic chip capacitors), which are also very low-impedance at low temperatures
Data Source
AI summary
A DC-DC converter includes an output-side storage capacitor arrangement which has a parallel circuit formed of an electrolytic capacitor, a ceramic capacitor and a circuit arrangement. The circuit arrangement has a series circuit formed of a hybrid electrolytic capacitor and a suppressor diode as well as a resistance connected in parallel with the hybrid electrolytic capacitor.