Railroad Propulsion Control Apparatus with Multi-Function Power Converters
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Solution Overview
Problem
Conventional propulsion control apparatuses for railroad vehicles with power storage devices require multiple power conversion devices, increasing cost, size, and mass, and suffer from reliability issues due to direct-current common unit abnormalities affecting connected devices.
Innovation Solution
A propulsion control apparatus with dual power converters that switch between DC/AC, AC/DC, and DC/DC conversion functions, along with line breakers controlled by control devices to manage power flow and isolate abnormalities, reducing the need for additional converters and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple power conversion devices are provided for DC/AC conversion and power storage charging/discharging, then the propulsion control apparatus can perform all required functions, but the cost, size, and mass of the apparatus increase
Solution Approach 1:
The patent applies multi-functionality by enabling a single power conversion device to perform multiple conversion functions (DC/AC, AC/DC, and DC/DC) through configurable operation modes. The power conversion device can switch between converting DC power from the overhead line to AC power for motors, converting AC power from motors to DC power for power storage devices, and converting DC power between different voltage levels for power storage charging/discharging, thereby eliminating the need for separate dedicated conversion devices for each function.
2Device complexity
If a direct-current common unit is used to share power among devices, then the system structure is simplified, but reliability decreases when an abnormality occurs in the common unit
Solution Approach 1:
The patent applies segmentation by dividing the power supply system into independent power supply paths. Instead of relying on a single direct-current common unit that all devices share, the system provides separate power supply paths where power conversion devices can independently convert power from the overhead line or power storage devices. This segmentation isolates abnormalities to specific segments, preventing them from affecting the entire system and thereby improving reliability while maintaining structural simplicity.
3Reliability
If power conversion devices are increased to improve reliability, then fault isolation is enhanced, but the number of devices and system complexity increase
Solution Approach 1:
The patent resolves this contradiction by using universal power conversion devices that can perform multiple conversion functions. Instead of increasing the number of dedicated conversion devices to improve reliability and fault isolation, the system employs configurable power conversion devices that can adapt to different operational requirements. This approach maintains a reduced number of devices while achieving reliable fault isolation through the flexible operational modes of the universal converters.
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 improves reliability without increasing the number of power converters, reduces apparatus size and cost, and allows regenerative power to be used as charging power between vehicles, enhancing power utilization and fault prevention.
Implementation Method 1
a first power converter that is configured to be able to connect to a direct-current common unit, that, when a direct-current power from the direct-current common unit is input from a first input/output end side and a first motor that generates a driving power for a vehicle is driven, operates as a DC/AC converter to convert the direct-current power into an alternating-current power
Implementation Method 2
when a direct-current power from the direct-current common unit is input from the first input/output end side and a power storage device is charged, operates as a DC/DC converter to convert the direct-current power into a direct-current power
Implementation Method 3
when a regenerative power from the first motor is input from the second input/output end side, operates as an AC/DC converter to convert the regenerative power into a direct-current power
Implementation Method 4
when the first control device detects that an abnormality has occurred in the direct-current common unit in accordance with a voltage value or (and) a current value detected in the direct-current common unit
Data Source
AI summary
A propulsion control apparatus includes a first power converter that operates as a DC/AC converter, a DC/DC converter, or an AC/DC converter, a second power converter, a first control device that controls operations of a first motor and the first power converter, and a second control device that controls operations of a second motor and the second power converter, wherein a power storage device is configured to be able to connect to a second input/output end side and functions as a direct-current power supply that is charged with direct-current power supplied from the second input/output end side or discharges direct-current power to the second input/output end side.