Railway Converter Switching Control for Low-Loss Power Transfer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing converters for railway vehicles experience increased energy losses and heating due to high switching frequencies, which also lead to larger size and weight, and soft switching techniques introduce additional losses and volume increase.
Innovation Solution
A converter design with a transformer, primary and secondary conversion stages, and a controller that adjusts switching times based on current measurements to minimize energy losses by ensuring zero current during switching, eliminating the need for resonance circuits and minimizing the size of switching elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the transformer frequency is increased to reduce size, then the converter size is reduced, but the switching frequency of switching elements increases leading to increased energy losses
Solution Approach 1:
The patent applies parameter changes by optimizing the switching frequency to a specific range (5 kHz to 20 kHz) that balances transformer size reduction with acceptable energy losses. By carefully selecting and controlling the switching frequency parameter, the invention achieves compact converter dimensions while maintaining reasonable efficiency without requiring soft switching techniques that would add complexity.
2Loss of energy
If soft switching techniques are used to reduce energy losses, then switching losses are reduced, but additional losses in transformer and increased volume occur
Solution Approach 1:
The invention extracts and eliminates the resonance circuit from the converter design. Instead of using soft switching techniques that require additional resonance components, the patent achieves low switching losses through optimized hard switching with carefully controlled switching frequency and timing, thereby removing the source of additional transformer losses and volume increase.
Solution Approach 2:
The patent employs simple, cost-effective switching elements (IGBTs or MOSFETs) with straightforward switching control rather than complex soft switching circuits. This approach uses readily available components with simple control logic to achieve acceptable switching losses without the need for expensive and bulky resonance circuits.
3Volume of moving object
If switching frequency is increased, then converter size is reduced, but dissipated energy increases leading to heating
Solution Approach 1:
The patent controls the switching frequency parameter within the optimal range of 5 kHz to 20 kHz to balance size reduction with thermal management. This parameter optimization ensures that switching losses remain acceptable and do not cause excessive heating, while still achieving significant size reduction compared to lower frequency designs.
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 reduces electrical losses and converter size while maintaining high efficiency, allowing for precise control of switching elements and preventing transformer saturation without an air gap, thus optimizing energy transmission.
Implementation Method 1
The converter comprises a transformer that provides galvanic isolation between a high-voltage supply of a railway line and a lower-voltage supply line of the railway vehicle
Implementation Method 2
Such a DC/DC conversion device comprises a plurality of switching elements comprising semiconductor devices such as transistors
Data Source
Figure 1
Figure 2
AI summary
Converter (1) for a railway vehicle comprising: - at least one primary conversion stage (3), and at least one secondary conversion stage (4), the primary stage (3) and the secondary stage (4) each comprising switching elements (12); - a transformer (2) configured to transmit energy between the primary stage (3) and the secondary stage (4) for the transformation of a first current (Ipri) under a first voltage (Vpri) received at the primary stage (3), into a second current (Isec) under a second voltage (Vsec); - at least one current sensor (6), the current sensor (6) being configured to measure at least the first current (Ipri), - a controller (7) configured to determine switching times of the switching elements (12) as a function of the measurement of the first current.