Locomotive Dynamic Brake Chopper Circuit
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Solution Overview
Problem
In diesel electric locomotives, the dynamic brake mode leads to a drop in DC link voltage due to fixed resistance in the dynamic brake grid, necessitating supplementary engine power and fuel consumption during braking, as the alternator struggles to maintain a steady voltage.
Innovation Solution
A power system with a chopper circuit and controller that selectively disables electrical communication between the resistor bank and traction motor for a predetermined duration, using a three-phase inverter module to regulate power dissipation in the dynamic brake grid, thereby controlling the magnitude of power dissipated to meet load requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dynamic brake grid uses fixed resistance to dissipate power, then the braking function is provided, but the DC link voltage drops and requires supplementary engine power
Solution Approach 1:
The patent applies dynamics by making the resistance value variable instead of fixed. The controller dynamically adjusts the resistance of the resistor bank based on the detected DC link voltage level. When voltage drops below a threshold, the controller increases resistance to limit current and prevent further voltage drop, thereby maintaining stable braking operation without requiring supplementary engine power.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the DC link voltage and using this information to adjust the resistor bank resistance. The controller receives voltage feedback from the DC link and automatically modifies the braking resistance to maintain voltage within acceptable ranges, creating a closed-loop control system that prevents voltage collapse during dynamic braking.
2Stability of the object's composition
If the alternator supports steady DC link voltage during dynamic braking, then voltage stability is maintained, but the engine must provide supplementary power
Solution Approach 1:
The patent applies dynamics by making the resistance value variable instead of fixed. The controller dynamically adjusts the resistance of the resistor bank based on the detected DC link voltage level. When voltage drops below a threshold, the controller increases resistance to limit current and prevent further voltage drop, thereby maintaining stable braking operation without requiring supplementary engine power.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the DC link voltage and using this information to adjust the resistor bank resistance. The controller receives voltage feedback from the DC link and automatically modifies the braking resistance to maintain voltage within acceptable ranges, creating a closed-loop control system that prevents voltage collapse during dynamic braking.
3Adaptability or versatility
If the chopper circuit disables electrical communication between resistor bank and traction motor, then power dissipation is controlled to meet load requirements, but the device complexity increases
Solution Approach 1:
The chopper circuit is designed to perform multiple functions: it acts as a variable resistance controller during dynamic braking, functions as a power dissipation regulator, and can operate in different braking modes. By integrating these functions into a single circuit design with controllable switches and a resistor bank, the patent reduces overall system complexity compared to having separate dedicated circuits for each function.
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 solution maintains the DC link voltage above a predetermined threshold, reducing the need for engine power during braking and minimizing fuel consumption by dynamically adjusting power dissipation based on load magnitude.
Implementation Method 1
The DB grid includes at least one resistor bank, and is configured to dissipate at least a portion of the power generated by the at least one traction motor
Data Source
AI summary
A power system for a locomotive includes a dynamic brake (DB) grid, at least one chopper circuit, and a controller. The locomotive includes at least one traction motor to power one or more loads during a braking of the locomotive. The DB grid includes at least one resistor bank and is configured to dissipate at least a portion of the power generated by the traction motor. The chopper circuit includes a three-phase inverter module, and selectively disables an electrical communication between the resistor bank and the traction motor. The controller is coupled to the chopper circuit and the loads. The controller determines a magnitude of the loads, and controls the chopper circuit to disable an electrical communication between the resistor bank and the traction motor for a predetermined duration to control a portion of the power dissipated by the DB grid to meet the magnitude of the loads.