Synchronous Machine EMC Filter Layout for Rotor Grounding
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Solution Overview
Problem
Existing separately excited synchronous machines face issues with increased EMC filter requirements due to larger core sizes, which increase costs and installation space, and noise voltages on the rotor shaft cause bearing damage and EMC problems.
Innovation Solution
A separately excited synchronous machine with a control circuit generating stator and rotor currents, featuring an EMC filter with a magnetic core and a ground connection through the core, where common-mode currents cancel each other out, allowing for a smaller core design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the core of the EMC filter is dimensioned larger to handle increased common-mode currents from separate excitation, then the EMC filtering capability is improved, but the installation space and cost increase
Solution Approach 1:
The harmful common-mode current is extracted from the excitation line and diverted through the ground connection through the core, separating it from the phase lines. This extraction allows the core to handle only the ground return current rather than the full common-mode current, enabling a smaller core size while maintaining EMC filtering effectiveness
Solution Approach 2:
The ground connection acts as an intermediary path that provides a controlled route for common-mode currents through the core. By introducing this intermediate ground path, the patent creates a dedicated current return route that reduces the burden on the core, allowing it to be dimensioned smaller while still providing effective EMC filtering
2Object-affected harmful factors
If the rotor shaft is grounded to reduce noise voltage, then bearing current damage is reduced, but the ground connection creates additional common-mode current paths that increase EMC filter requirements
Solution Approach 1:
The patent merges the ground connection function with the EMC filter core by routing the ground connection through the magnetic core. This combination allows the ground path to serve dual purposes: protecting bearings from current damage while simultaneously providing a controlled path for common-mode currents through the core, thereby reducing the burden on separate EMC filter components
Solution Approach 2:
The patent converts the potentially harmful ground connection, which creates common-mode current paths, into a beneficial element by routing it through the EMC filter core. The ground connection's common-mode currents now contribute to the filtering action rather than opposing it, as the core provides a controlled path that dissipates these currents harmlessly
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 reduces EMC filter size and cost, minimizes noise-induced bearing damage, and mitigates EMC issues by canceling common-mode currents, optimizing core dimensions and routing.
Implementation Method 1
at least one EMC filter is arranged between the second circuit and the rotor winding, having at least one core made of a magnetic material
Implementation Method 2
The advantage is that this allows the common-mode currents in the core to cancel each other out
Implementation Method 3
the ground connection from the rotor passing through the at least one core. The advantage is that this allows the common-mode currents in the core to cancel each other out
Data Source
Figure 1~2
Figure 1
AI summary
The invention relates to a separately excited synchronous machine (3) with a control circuit, wherein the control circuit comprises a first circuit (6) for generating the stator currents and a second circuit (8) for generating a rotor current, wherein the second circuit (8) is connected to a rotor winding of the separately excited synchronous machine (3) via lines (9), wherein at least one EMC filter (11) is arranged between the second circuit (8) and the rotor winding, the filter having at least one core (12) made of a magnetic material, wherein a rotor of the separately excited synchronous machine (3) is connected to ground by means of a ground connection (14), wherein the ground connection (14) is led from the rotor through the at least one core (12), and a traction network (1).