Active Rectifier Surge Protection via Inductive Segmentation
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Solution Overview
Problem
Conventional switched mode power supplies (SMPS) are vulnerable to voltage surges, which exceed the maximum pulse current rating of MOSFETs in active rectifier bridges, leading to potential damage during industrial or consumer product applications.
Innovation Solution
A switching converter circuit is designed with a combination of a passive diode rectifier and an active rectifier bridge, where inductors are connected between the two rectifiers to divert surge currents away from the MOSFETs, reducing peak currents and enhancing robustness against voltage surges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an active rectifier bridge with MOSFETs is used to improve efficiency, then power dissipation losses are reduced, but the circuit becomes vulnerable to voltage surges exceeding MOSFET ratings
Solution Approach 1:
The rectifier system is segmented into two independent paths: an active rectifier bridge for normal operation and a passive diode rectifier for surge protection. The inductors segment the current paths, allowing selective routing of surge currents away from MOSFETs while maintaining efficient active rectification during normal operation.
Solution Approach 2:
Inductors are introduced as intermediary components between the active rectifier bridge and the AC input. These inductors act as mediators that naturally divert high di/dt surge currents away from the MOSFETs due to their opposition to rapid current changes, while allowing normal rectification current to pass through the active bridge.
2Reliability
If a passive diode rectifier is used to protect against voltage surges, then robustness is improved, but efficiency is reduced due to higher power dissipation
Solution Approach 1:
The system dynamically adapts its rectification path based on operating conditions. During normal operation, the active rectifier bridge handles the load with high efficiency. During voltage surge events, the inductors dynamically redirect surge currents to the passive diode rectifier path, which is inherently more robust against overvoltage conditions.
Solution Approach 2:
Different parts of the rectifier system have different qualities optimized for different functions: the active rectifier bridge provides high efficiency for normal operation, while the passive diode rectifier provides robustness for surge conditions. The inductors enable local selection of the appropriate rectification path based on instantaneous conditions.
3Reliability
If inductors are added between the passive and active rectifiers to divert surge currents, then robustness against voltage surges is improved, but device complexity increases
Solution Approach 1:
The inductors serve multiple functions simultaneously: they limit di/dt to protect MOSFETs during surges, they enable current sharing between the two rectifier paths, and they can be integrated with existing EMI filter inductors in the power supply design, reducing the need for additional discrete components.
Solution Approach 2:
The protection function is merged with the existing rectifier topology by adding inductors to the standard dual-rectifier configuration. The inductors are integrated into the current paths of both rectifiers, creating a unified system where the same components serve both rectification and protection functions.
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
This configuration effectively reduces the maximum current passing through MOSFETs during voltage surges, protecting them while maintaining the efficiency of active rectification, thereby improving the overall robustness and reliability of SMPS systems.
Implementation Method 1
an inductive component coupled between the input of the passive rectifier circuit and a corresponding input of the active rectifier circuit
Data Source
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AI summary
A switching converter circuit, which can be used for power factor correction (PFC) is described herein. In accordance with one embodiment, the switching converter circuit includes a passive rectifier circuit that has an input for receiving an alternating input voltage, an active rectifier circuit, and an inductive component coupled between the input of the passive rectifier circuit and a corresponding input of the active rectifier circuit. Furthermore, the switching converter circuit includes a switching circuit including at least one inductor and at least one electronic switch, wherein the switching circuit is coupled to the active rectifier circuit and configured to provide a DC output voltage by operating the switching circuit in accordance with a predefined switching scheme.