Rail Vehicle Transformer Secondary Winding Saturation Control
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Solution Overview
Problem
Railway vehicle traction chains with non-linear input chokes under DC power supply face operational deterioration, which is currently addressed by adding a short-circuited winding to saturate the magnetic circuit, but this increases mass and cost.
Innovation Solution
Determining and controlling the current through the secondary winding of the transformer to ensure a minimum current greater than the saturation current, thereby preventing non-linearity without adding additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the secondary winding of the transformer is used as an input choke under DC power supply, then the device complexity is reduced, but the input choke becomes highly non-linear due to non-saturation of the magnetic circuit
Solution Approach 1:
The invention changes the operating parameter of the magnetic circuit by ensuring it operates in the saturation zone through controlled current injection from the braking chopper. This transforms the non-linear input choke into a linear component by maintaining stable magnetic saturation, thereby improving operation stability while keeping the device complexity low.
Solution Approach 2:
The braking chopper is used as an intermediary device to inject controlled current into the secondary winding, which acts as the input choke. This intermediary current injection ensures the magnetic circuit operates in the saturation zone, stabilizing the inductance of the input choke without requiring additional dedicated saturation windings.
2Reliability
If an additional short-circuited winding is added to saturate the magnetic circuit, then the operation stability is improved, but the weight and cost increase
Solution Approach 1:
The secondary winding of the transformer serves multiple functions: it acts as the input choke under DC power supply and can be saturated by controlled current from the braking chopper. This multi-functional approach eliminates the need for separate saturation windings, reducing vehicle mass while maintaining operation stability.
Solution Approach 2:
The braking chopper, which is already part of the traction chain, is utilized to provide the saturating current for the input choke. This self-service approach allows the existing braking system to also perform the function of magnetic circuit saturation, avoiding additional components and reducing overall vehicle mass.
3Reliability
If an additional short-circuited winding is added to saturate the magnetic circuit, then the operation stability is improved, but the manufacturing cost increases
Solution Approach 1:
The secondary winding performs dual functions as both the input choke and the saturation-winding equivalent. This eliminates the need for additional windings and associated manufacturing processes, reducing manufacturing cost while maintaining operation stability through controlled current injection from the braking chopper.
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 approach stabilizes the operation of traction converters, avoiding the need for additional components and reducing costs and mass, ensuring reliable operation under both DC and AC power supplies.
Implementation Method 1
controlling the braking chopper to ensure in said secondary winding a minimum current greater than the saturation current of the choke
Data Source
Figure 1~2
AI summary
The method involves connecting a secondary winding of a transformer of a power train of a rail vehicle to a self inlet (3) of the power train of the vehicle, and determining current passing in the secondary winding of the transformer when the secondary winding is connected to the self inlet of the power train. A braking vibrator i.e. rheostat (7), of the power train is controlled in a manner for assuring minimum current that is higher than saturation current of the self inlet of the power train, in the secondary winding.