Half-Bridge Active Rectifier Overvoltage Protection
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Solution Overview
Problem
Active bridge rectifiers face challenges in overvoltage protection during load dump events, as the energy storage capacitors used for voltage supply are not reloaded in the low-side path, leading to potential overvoltage damage to downstream components.
Innovation Solution
A half-bridge configuration with controllable switching elements and capacitors, where the capacitors are fed via a positive DC voltage connection, ensuring continued voltage supply even during active short circuits, and a third control element manages overvoltage by creating an active short circuit between the DC and ground connections, maintaining power supply to the switching elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first switching element creates a short circuit between the AC voltage connection and the ground connection for overvoltage protection, then downstream components are protected from overvoltage damage, but the first capacitor can no longer be reloaded and the control elements lose power supply
Solution Approach 1:
A second capacitor is introduced as an intermediary energy storage element that takes over the power supply function when the first capacitor can no longer be reloaded during an active short circuit. This mediator ensures continuous operation of the control elements without compromising the overvoltage protection function.
Solution Approach 2:
The second capacitor is pre-charged from the positive DC voltage connection before the overvoltage event occurs. When the active short circuit is activated and the first capacitor can no longer be reloaded, the second capacitor already has stored energy available to immediately take over the power supply function, ensuring no interruption in control element operation.
2Reliability
If a third control element is added to close the first switching element in the event of overvoltage, then active short circuit protection is enabled, but the device complexity increases
Solution Approach 1:
The third control element is designed to perform multiple functions: it detects overvoltage conditions, activates the active short circuit protection by closing the first switching element, and coordinates with the second capacitor to maintain power supply. This multi-functionality justifies the additional component by consolidating several protection and control functions into a single element.
3Use of energy by moving object
If the capacitors are fed via the positive DC voltage connection instead of the AC voltage connection, then continuous power supply is ensured during active short circuits, but the circuit configuration becomes more complex
Solution Approach 1:
The positive DC voltage connection serves as an intermediary power source that can supply energy independently of the AC voltage connection status. By feeding the capacitors from this stable DC source rather than from the AC side, the system ensures that control elements maintain power supply even when the AC connection is shorted to ground during overvoltage events.
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 ensures the active rectifier's functionality is maintained during overvoltage events by ensuring continuous power supply to the control elements, preventing damage to downstream components and maintaining the active short circuit control.
Implementation Method 1
A first capacitor (114) used for a voltage supply of the first control element (112) is fed via a positive DC voltage connection (120)
Implementation Method 2
A second capacitor (124) used for a voltage supply of the second control element (122) is also fed from the positive DC voltage connection (120)
Implementation Method 3
a first controllable switching element (111), via which an AC voltage connection (110) of the half-bridge is connected to a ground connection (130) of the half-bridge
Implementation Method 4
a second controllable switching element (121), via which the AC voltage connection (110) is connected to the positive DC voltage connection (120)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a half-bridge (200) for an active rectifier, having an AC voltage connection (110), a positive DC voltage connection (120) and an earth connection (130), wherein a first switching element (111) connects the AC voltage connection (110) to the earth connection (130); wherein a second switching element (121) connects the AC voltage connection (110) to the positive DC voltage connection (120), wherein a first control element (112) for switching the first switching element (111) is connected to the first switching element (111); wherein a connection of a first capacitor (114) is connected to a voltage supply connection of the first control element (112); wherein the positive DC voltage connection (120) is connected to the one connection of the first capacitor (114) via a first diode (113) in the forward direction; wherein the first capacitor (114) is connected in parallel with a series circuit comprising the first switching element (111) and the second switching element (121).