Multilayer PCB Clamping Path for Low-Inductance Braking Resistance
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Solution Overview
Problem
Existing printed circuit boards (PCBs) with braking resistors face challenges in achieving low inductance while maintaining sufficient thermal capacitance and electrical resistance, which is crucial for efficient energy conversion during high-current switching operations.
Innovation Solution
The implementation of a braking resistor as a clamping path on a printed circuit board, utilizing at least two conductive layers closely spaced to form a low-inductance closed conductor loop, with an additional meander-shaped arrangement to further reduce inductance and adjust thermal capacitance without affecting electrical resistance or inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a clamping path is implemented on an outer layer of the PCB, then the electrical resistance and thermal capacitance can be adjusted, but the inductance becomes relatively high
Solution Approach 1:
The clamping path transitions from a two-dimensional outer layer trace to a three-dimensional structure utilizing multiple inner layers. The conductive paths are arranged in adjacent layers with perpendicular orientations, creating a compact loop that reduces the enclosed area and thus the inductance while maintaining thermal mass through the multi-layer construction.
Solution Approach 2:
The clamping path is nested within the multi-layer PCB structure, with conductive paths in different layers embedded within the board thickness. This nesting allows the current loop to be confined to a small volume, reducing the loop area and inductance while the distributed copper mass across layers provides sufficient thermal capacitance.
2Speed
If the current increases very quickly in the clamping path, then the braking effect is improved, but the induced voltage counteracts the current flow due to high inductance
Solution Approach 1:
By moving the clamping path to inner layers and utilizing the third dimension (layer stacking), the current loop area is minimized. The perpendicular arrangement of conductive paths in adjacent layers creates a compact structure that reduces inductance, allowing faster current rise rates without excessive induced voltage counteracting the braking effect.
3Device complexity
If the resistance path is implemented using SMD resistors, then the pre-charge and clamping functions are realized, but the thermal mass is insufficient for high current switching
Solution Approach 1:
The clamping path merges multiple functions into a single integrated PCB trace structure. The multi-layer conductive paths serve simultaneously as current carriers, thermal mass reservoirs, and low-inductance braking elements. This eliminates the need for separate SMD resistors while providing sufficient thermal capacitance through the distributed copper mass across multiple layers.
Solution Approach 2:
The multi-layer PCB clamping path structure performs multiple functions: it provides the resistance path for current limiting, serves as thermal mass for energy absorption, and maintains low inductance for fast response. This universal structure replaces multiple discrete components with a single integrated solution that handles pre-charge, clamping, and braking 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 design achieves a significantly low-inductance clamping path, allowing for efficient energy conversion and reduced run-down times of electric motors, while maintaining the necessary thermal capacitance and electrical resistance.
Implementation Method 1
the clamping path can convert the energy of the electromagnetic fields into thermal energy
Implementation Method 2
it is known that the run-down times of an electric motor can be reduced by using a brake circuit that has such a braking resistor. This is achieved by short-circuiting the generator voltage of the electric motor via a load resistor when it runs down, thereby generating an electromagnetic braking torque
Data Source
AI summary
A printed circuit board in which a braking resistor is implemented that is designed as a clamping path. The clamping path is formed by at least two conductive layers within the printed circuit board that run at a distance from one another and allow a current to flow back and forth.