Rectifier Circuit Damping Unit for Overcurrent Oscillations
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Solution Overview
Problem
Converter circuits experience undesirable oscillations of overcurrent, which can damage or destroy controllable power semiconductor switches due to the lack of damping mechanisms in existing designs.
Innovation Solution
Incorporation of a passive, non-controllable damping unit with a diode and damping resistor, connected in series with the existing snubber network components, to dampen overcurrent oscillations, providing a simple, robust, and cost-effective solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a snubber network with resistor, inductor, capacitor and diode is used to limit current rise rate, then the voltage peaks and high-frequency oscillations are reduced, but the overcurrent oscillations cannot be damped and may damage power semiconductor switches
Solution Approach 1:
The patent divides the protection function into two separate networks: the original snubber network (with resistor, inductor, capacitor and diode) for limiting voltage peaks and high-frequency oscillations, and a new damping network (with damping resistor and damping diode) specifically for damping overcurrent oscillations. This segmentation allows each network to optimize its function without interfering with the other, resolving the contradiction between voltage peak reduction and overcurrent damping.
Solution Approach 2:
The damping diode acts as an intermediary element that is conductive only during overcurrent conditions. It provides a dedicated path for damping oscillations without affecting normal operation or voltage peak limiting functions. The damping resistor, activated only when the damping diode conducts, serves as a mediator that dissipates oscillation energy without causing continuous power loss.
2Reliability
If additional damping components are added to the snubber network, then overcurrent oscillations can be damped, but the device complexity and cost increase
Solution Approach 1:
The damping network uses simple, inexpensive components - a damping resistor and a damping diode - that can be easily added to existing converter circuits. These components are designed to be activated only during fault conditions (overcurrent oscillations), providing effective damping without requiring complex active control circuits or expensive specialized components.
Solution Approach 2:
The damping network is merged with the existing snubber network by sharing common connection points (connected in parallel across the capacitive energy storage device). The damping diode is connected in parallel with the snubber network capacitor, and the damping resistor is connected in series with the damping diode. This merging approach allows the damping function to be integrated into the existing protection structure without requiring completely separate wiring and mounting space.
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
Effectively reduces overcurrent oscillations, protecting semiconductor switches and allowing for easy retrofitting in existing converter circuits without additional discrete damping resistors, thereby enhancing reliability and reducing component costs.
Implementation Method 1
the passive non-controllable damping unit having a diode and a damping resistor
Implementation Method 2
the passive non-controllable damping unit having a diode and a damping resistor, the diode having a unidirectional direction of current conduction
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a rectifier circuit having a rectifier unit (1), said rectifier unit (1) comprising a plurality of actuatable power semiconductor switches, the DC side thereof being connected to a capacitive energy storage circuit (2), wherein the capacitive energy storage circuit (2) comprises at least one capacitive energy store and at least one load shedding network (3) for limiting the rate of increase of the current or voltage at the actuatable power semiconductor switches of the rectifier unit (1). In order to reduce undesired oscillations of an overcurrent in the capacitive energy storage circuit, the capacitive energy storage circuit (2) comprises at least one passive, non-actuatable damping unit (4) having a unidirectional current passage direction, wherein the passive, non-actuatable damping unit (4) comprises a diode and a damping resistor.