Rail Vehicle Compressor Speed Control via Frequency Converter
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Solution Overview
Problem
Compressors in rail vehicles face challenges in balancing high delivery rate, low noise emissions, low energy consumption, and cost-effectiveness across varying operating states, often resulting in inefficient energy use and noise pollution due to fixed operating speeds and direct fan operation with the compressor.
Innovation Solution
A compressor system with an actuator controlling the electric machine's speed and a separately controlled cooling fan, allowing for variable operation between maximum and minimum speeds based on the rail vehicle's state, optimizing energy use and noise reduction by adjusting speed according to specific operational needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the compressor is operated at constant nominal speed in on/off mode, then the compressor can be simply controlled and manufactured, but energy consumption is high and noise emissions occur during station operation
Solution Approach 1:
The compressor speed is made dynamically adjustable through a frequency converter that enables continuous speed variation between minimum and maximum speeds, allowing the system to adapt to different operational requirements and reduce energy consumption during station operation while maintaining simple control architecture
2Productivity
If the compressor is dimensioned for continuous operation at rated speed, then sufficient delivery rate is achieved, but noise emissions increase during station stops
Solution Approach 1:
The system uses dynamic speed adjustment to operate the compressor at minimum speed during station operation when lower delivery rate suffices, and at maximum speed during line operation when high delivery rate is required, thereby reducing noise emissions during station stops while maintaining sufficient productivity during operation
Solution Approach 2:
The compressor speed parameter is continuously variable through frequency converter control, enabling the system to optimize between delivery rate and noise emissions by selecting appropriate speed levels based on operational context
3Device complexity
If the cooling fan is directly driven by the compressor, then the system structure is simple, but the fan operates at high speed causing increased noise emissions during station operation
Solution Approach 1:
The direct coupling between compressor and cooling fan is segmented by introducing an independent motor drive for the fan, allowing the fan to be controlled separately from the compressor operation, thereby enabling noise reduction during station operation while maintaining simple overall system structure
Solution Approach 2:
The independent motor drive for the cooling fan provides multi-functionality by enabling the fan to operate independently of compressor speed, allowing optimized cooling during operation and noise reduction during station stops
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 energy consumption and noise emissions by optimizing compressor speed and fan operation, enabling efficient energy recovery during braking and minimizing noise during station stops, while allowing for a more compact design and reduced water vapor in compressed air, thus enhancing overall system performance.
Implementation Method 1
a compressor (3) driven by an electric machine (1) via a drive shaft (2)
Data Source
Figure 1~2
AI summary
The invention relates to a compressor system for a rail vehicle, comprising a compressor (3), driven by an electrical machine (1) via a drive shaft (2), for producing compressed air for at least one compressed air tank (4), wherein the electrical machine (1) can be activated at least indirectly via a control device (5) for operating the electrical machine (1) at at least one nominal speed (n) between a maximum speed (m) and a minimum speed (i), wherein furthermore at least one pressure sensor (7) for determining the pressure for the control device (5) is disposed in a compressed-air-carrying line (6) downstream of the compressor (3). According to the invention, a final control element (8) for continuously influencing the speed of the electrical machine (1) is disposed between an electrical supply (15) and the electrical machine (1), wherein the activation of the final control element (8) takes place via the control device (5). Furthermore, the invention also relates to a method for controlling the compressor system according to the invention, wherein, in dependence on an operating state of the rail vehicle, the compressor (3) is operated at a variable speed, assuming any intermediate value between the maximum speed (m) and the minimum speed (i).