Switching Circuit Rectifier Capacitor Voltage Ringing
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Solution Overview
Problem
Insulated gate field-effect transistors (IGFETs) in switching circuits experience parasitic characteristics that lead to voltage ringing, overshoot, and potential damage due to parasitic resistance and inductance, which are not adequately addressed by existing designs.
Innovation Solution
Incorporating rectifying elements, such as Schottky diodes, and charge storage elements, like capacitors, in parallel with switching elements to mitigate parasitic effects by providing a low impedance path for excess charge and reducing voltage fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If switching elements (IGFETs) are used to provide voltage switching capability, then the circuit can achieve higher voltage or lower voltage output, but parasitic resistance and inductance cause voltage ringing and overshoot that can exceed breakdown voltage and damage components
Solution Approach 1:
A diode is introduced as an intermediary component connected between the source of the first switching element and the drain of the second switching element. This diode provides a controlled current path that mediates the parasitic inductance effects, allowing the circuit to achieve voltage switching while limiting voltage overshoot and ringing to safe levels.
Solution Approach 2:
The parasitic inductance that causes harmful voltage ringing is converted into a beneficial effect by utilizing the diode's forward voltage drop. The diode's presence transforms the potentially damaging oscillations into a controlled current flow that maintains voltage within safe operating limits, effectively using the parasitic element's energy in a constructive manner.
2Measurement precision
If parasitic characteristics are modeled with resistance and inductance, then the circuit behavior can be analyzed, but the parasitic effects cause significant voltage overshoot that can damage the load
Solution Approach 1:
The diode is positioned in the circuit to provide beforehand cushioning against voltage overshoot. By being pre-configured in the current path, the diode is ready to clamp voltage excursions before they can reach damaging levels, cushioning the load against the harmful effects of parasitic inductance during switching transitions.
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 significantly reduces voltage overshoot and ringing at the output terminal, ensuring the switching circuit operates within safe voltage limits and preventing damage to the load, with improved performance compared to traditional designs.
Implementation Method 1
Incorporating rectifying elements, such as Schottky diodes, and charge storage elements, like capacitors, in parallel with switching elements to mitigate parasitic effects by providing a low impedance path for excess charge
Implementation Method 2
Incorporating rectifying elements, such as Schottky diodes, and charge storage elements, like capacitors, in parallel with switching elements to mitigate parasitic effects
Data Source
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AI summary
A circuit (200, 300) can include a pair of switching elements (222, 224, 322, 324) that have terminals electrically connected to terminals of a power supply (202) and have other terminals electrically connected to an output terminal. The circuit (200, 300) can include rectifying elements (242, 244, 342, 344) and one or more charge storage elements (262, 264, 362, 364). The circuit may be used as a Buck converter. The rectifying element(s) (242, 244, 342, 344) and charge storage element(s) (262, 264, 362, 364) may help to reduce ringing at an output terminal of the circuit (200, 300) during normal operation and reduce the likelihood of exceeding a breakdown voltage between current-carrying electrodes of a switching element within the circuit (200, 300) during a switching operation.