Railway Vehicle Control Apparatus Power Conversion Isolation
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Solution Overview
Problem
The existing railway vehicle control apparatus requires a contactor and current reduction means, leading to increased complexity, reliability issues, and safety concerns due to potential contacts between high voltage and low voltage circuits during charging and operation.
Innovation Solution
A railway vehicle control apparatus with a first power conversion device having a primary and secondary circuit, each with a switching element, and a controller that manages bidirectional power conversions to prevent such contacts by activating one switching element while deactivating the other, allowing for efficient power supply to the generator without a contactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contactor and current reduction means are used to charge the smoothing capacitor and prevent backflow, then power conversion control is achieved, but the number of parts increases leading to decreased reliability and increased costs
Solution Approach 1:
The patent removes the contactor from the system by using the switching elements of the first and second power conversion devices to perform the isolation function. The switching elements are already present for power conversion control, so their additional function eliminates the need for separate contactor hardware, reducing part count while maintaining reliability.
Solution Approach 2:
The switching elements of the power conversion devices are made multi-functional: they perform both power conversion control and circuit isolation functions. This universal usage eliminates dedicated isolation components, simplifying the overall system structure while maintaining the necessary safety functions.
2Object-affected harmful factors
If a contactor is used to prevent contact between high voltage and low voltage circuits, then safety is improved, but device complexity and cost increase
Solution Approach 1:
The contactor is extracted from the system as a separate component. Its isolation function is absorbed by the switching elements of the power conversion devices, which can already open and close circuits. This eliminates the need for additional safety hardware while maintaining the same protective function.
Solution Approach 2:
The switching elements act as intermediaries between high and low voltage circuits. By controlling the state of these switching elements, the system achieves electrical isolation without requiring a physical contactor, thereby maintaining safety while reducing component count.
3Reliability
If a contactor is used to prevent backflow of electric power, then power flow control is achieved, but device complexity increases
Solution Approach 1:
The switching elements are made universal to perform both power conversion and power flow direction control. By appropriately controlling which switching elements are on or off, the system can prevent backflow of power to the smoothing capacitor without requiring a separate check valve or diode circuit, thus simplifying the system.
4Power
If the smoothing capacitor is charged from the electric power storage means, then the capacitor can supply power for generator starting, but the voltage difference creates safety risks when contactor fails
Solution Approach 1:
The contactor that created the safety hazard is removed from the system. The charging function is achieved through the switching elements of the power conversion devices, which provide inherent electrical isolation when open. This eliminates the risk of accidental contact between high and low voltage circuits while maintaining the power charging capability.
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 configuration simplifies the system, prevents contacts between high and low voltage circuits, and ensures reliable power supply to the generator driven by internal combustion engines, enhancing safety and reducing costs.
Implementation Method 1
the first power conversion device performs bidirectional power conversions between a primary side and a secondary side. When one of either the switching element of the primary circuit or the switching element of the secondary circuit is activated, the controller performs control to deactivate the other switching element
Implementation Method 2
a generator including a stator and an armature, the stator having a field winding, and the armature having an armature winding
Implementation Method 3
a smoothing capacitor connected to secondary side terminals of the second power conversion device and connected to terminals of the primary side of the first power conversion device
Data Source
AI summary
A primary circuit and a secondary circuit each have a switching element, each operate as a power conversion circuit while the switching element is activated, and each operate as a rectifier circuit while the switching element is deactivated. While a generator provided at the primary side of a first power conversion device is stopped, a controller activates the switching element of the secondary circuit and deactivates the switching element of the primary circuit. Accordingly, the first power conversion device converts electric power input from the secondary side and supplies electric power for causing the generator to operate. While the generator is operated, the controller activates the switching element of the primary circuit and deactivates the switching element of the secondary circuit such that the first power conversion device converts electric power supplied from the generator and outputs the converted electric power to the secondary side.