Brake Chopper Switching for Regenerative Overhead Line Vehicles
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Solution Overview
Problem
Existing electric drive vehicles face issues with regenerative efficiency and the increase of overhead line voltage when there is no electrical storage facility on the overhead line voltage, and the increase of overhead line voltage when there is no electrical storage facility on the ground or when there are no other vehicles driving on the overhead line, leading to reverse power flow and increased DC voltage of the inverter.
Innovation Solution
The electric drive vehicle includes a DC/DC converter, an inverter, a brake chopper apparatus with a switching element, resistance, and diode, and a controller that switches operation conditions based on connection to the overhead line, to suppress reverse power flow and DC voltage increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative electric power is supplied to the overhead line, then regenerative efficiency is improved, but overhead line voltage increases when there is no electrical storage facility on the ground
Solution Approach 1:
The patent introduces an intermediary system consisting of a brake chopper apparatus and switching element that mediates between the regenerative power source and the overhead line. When the overhead line cannot accept regenerative power (no storage facility or other vehicles), the switching element activates the brake chopper to dissipate excess energy through resistance, preventing voltage increase while still allowing regenerative braking to occur when conditions permit
Solution Approach 2:
The patent implements dynamic switching between different operational modes based on real-time conditions. The control device monitors overhead line voltage and storage facility status, dynamically switching between regenerative mode (when overhead line can accept power) and brake chopper mode (when it cannot), thereby adapting the system behavior to current conditions to optimize both regenerative efficiency and voltage stability
2Loss of energy
If regenerative electric power is supplied to the overhead line, then regenerative efficiency is improved, but DC voltage of the inverter increases when the overhead line is not laid
Solution Approach 1:
The brake chopper apparatus serves as an intermediary between the inverter and the power supply system. When operating on sections without overhead lines, the switching element activates the brake chopper to provide a controlled discharge path for regenerative energy through the resistance, preventing DC voltage increase in the inverter while still capturing regenerative energy when possible
Solution Approach 2:
The patent converts the potentially harmful effect of excess regenerative energy (which causes voltage increase) into a beneficial outcome by using the brake chopper's resistance to dissipate controlled amounts of energy. This transforms the harmful voltage buildup into a controlled energy management strategy, where the resistance acts as a safety valve to protect the inverter while still allowing regenerative braking to function
3Object-generated harmful factors
If battery absorbs all regenerative electric power, then reverse power flow is suppressed, but battery may not be able to absorb all power depending on state of charge
Solution Approach 1:
The patent creates a multi-functional power management system that can handle multiple scenarios: when battery state of charge allows, the battery absorbs regenerative power; when it doesn't, the brake chopper apparatus takes over to dissipate excess energy. The switching element enables this universal system to adapt between different operational modes, ensuring reverse power flow is suppressed regardless of battery conditions
Solution Approach 2:
The switching element acts as an intermediary that monitors battery state of charge and dynamically selects the appropriate power absorption method. When the battery can absorb power, the switching element routes energy to the battery; when the battery is full or cannot absorb sufficient power, the switching element activates the brake chopper apparatus, ensuring continuous protection against reverse power flow
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 effectively suppresses adverse effects from regenerative electric power during braking operations, maintaining stable DC voltage levels in the inverter.
Implementation Method 1
a brake chopper apparatus including a switching element, a resistance, and a diode, which is connected to the DC side of the inverter
Implementation Method 2
a brake chopper apparatus including a switching element, a resistance, and a diode, which is connected to the DC side of the inverter
Data Source
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AI summary
The electric drive vehicle includes a battery, a DC/DC converter that uses the output voltage of the battery as input, an inverter that drives the electric motor using the voltage output by the DC/DC converter or the voltage output by the overhead line as input, and a brake chopper apparatus that includes a switching element, a resistance and a diode, which is connected to the DC side of the inverter. The electric drive vehicle switches the conditions under which the switching element operates when the electric drive vehicle is connected to the overhead line and when the electric drive vehicle is not connected to the overhead line.