Electric Vehicle Control Device Pantograph Current Adjustment
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Solution Overview
Problem
Electric vehicles equipped with power storage devices face inefficiencies in charging during non-electrified sections, particularly when pantographs are partially defective, leading to excessive temperature rises and potential damage during both traveling and stopping, as the system fails to adjust current levels effectively based on pantograph contact states and vehicle speed.
Innovation Solution
An electric vehicle control apparatus featuring a power converting unit with a current adjusting unit that generates current commands based on pantograph contact state and vehicle speed signals, adjusting the charging current to prevent overheating by limiting the input current when any pantograph is not in a normal contact state, thereby dispersing the current load safely across functional pantographs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large current is fed to the pantograph during stop charging, then charging speed is improved, but temperature rise at contact point increases excessively
Solution Approach 1:
The patent applies dynamics by making the current limit value variable based on vehicle speed. When the vehicle is moving, a higher current limit is permitted because the pantograph contact point experiences cooling from air flow. When the vehicle is stopped, a lower current limit is enforced to prevent excessive temperature rise. This dynamic adjustment resolves the contradiction between charging speed and temperature control.
Solution Approach 2:
The patent changes the parameter of current limit value based on operating conditions (vehicle speed and pantograph contact state). By adjusting this electrical parameter dynamically, the system achieves both fast charging when conditions permit and temperature control when conditions require it, resolving the technical contradiction.
2Temperature
If multiple pantographs are used to disperse current load, then temperature rise is reduced, but device complexity increases
Solution Approach 1:
The patent segments the pantograph system into multiple independent units, each capable of making contact with the overhead wire. This segmentation allows the current load to be distributed across multiple contact points, reducing temperature rise at each individual point while maintaining system reliability.
3Productivity
If charging current is increased during non-electrified section travel, then power storage device charging efficiency is improved, but energy loss increases due to friction brake supplementation
Solution Approach 1:
The patent implements feedback control by continuously monitoring the state of pantograph contacts and adjusting the current limit accordingly. This ensures optimal charging current is applied based on real-time conditions, maximizing charging efficiency while avoiding excessive current that would require friction brake supplementation and cause energy loss.
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
Enables safe and efficient charging of power storage devices during both travel and stoppage by preventing excessive temperature rises at pantograph contact points, thereby extending the lifespan of pantographs and overhead wires while maintaining optimal charging capacity.
Implementation Method 1
a voltage is applied to the pantograph... the electric vehicle detects the voltage with an electric vehicle control apparatus and starts a charging operation for the power storage device via a power converting unit
Implementation Method 2
a power converting unit that converts a voltage input through the current collectors into a direct current having a predetermined value
Implementation Method 3
heat generating points by contact resistance... a relatively large current can be fed to the pantograph
Data Source
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AI summary
An electric vehicle control apparatus includes a plurality of current collectors that take in electric power from an outside, a convertor unit that converts a voltage input through the current collectors into a direct current having a predetermined value and outputs the direct current, and a power storage unit connected to and charged and discharged by the convertor unit. The convertor unit includes a convertor circuit and a control unit (14). The control unit (14) includes a current adjusting unit (66) that generates a current command which is a command for an electric current of the convertor circuit, and adjusts the magnitude of the current command on the basis of a current collector state signal. The current collector state signal indicates whether the current collectors are in a state in which the current collectors can normally take in the electric power from the outside. The control unit (14) further includes a current control unit (67) that controls the electric current of the convertor circuit on the basis of the current command.