Active High Voltage Bus Bleed Down via Generator Motoring
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Solution Overview
Problem
High voltage electrical buses take a long time to return to a low energy state after disconnection, necessitating extended wait times for repairs and maintenance, and existing bleeder resistors are inefficient and prone to failure, posing safety risks.
Innovation Solution
An active bleed down system that monitors engine speed and bus voltage thresholds, enabling generators and auxiliary devices to discharge excess voltage by switching into motoring mode, safely and efficiently reducing bus voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bleeder resistor is used to dissipate stored energy, then energy dissipation is provided, but the discharge rate is limited to a natural rate of decay requiring substantial wait time
Solution Approach 1:
The system dynamically switches the generator between generating mode and motoring mode based on real-time monitoring of engine speed and bus voltage. When the engine slows down and bus voltage remains high, the generator is switched to motoring mode to actively consume power and accelerate discharge, creating a dynamic response that adapts to changing conditions rather than relying on passive resistor discharge
Solution Approach 2:
The system changes the operating parameters of the generator by switching its mode of operation. By changing the generator's role from power source to power consumer, the system fundamentally alters the electrical circuit configuration to achieve faster discharge rates, transforming the generator's electrical characteristics based on system needs
2Reliability
If a bleeder resistor is used for discharge, then some energy dissipation is achieved, but the discharge circuit is susceptible to failure posing safety risks
Solution Approach 1:
The generator serves dual purposes: it generates power during normal operation and automatically switches to consuming power for discharge when needed. This self-service capability eliminates the need for separate passive discharge components like bleeder resistors, using the existing generator to perform both power generation and power consumption functions based on system conditions
Solution Approach 2:
The generator is designed to perform multiple functions within the same system - acting as both a power source during operation and a power sink for discharge. This multi-functionality consolidates the electrical system's components, eliminating the need for separate discharge resistors and reducing the overall number of failure points in the system
3Reliability
If technicians must wait for the electrical bus to return to low energy state, then safety is maintained, but total repair and maintenance time is compounded dramatically
Solution Approach 1:
The system continuously monitors engine speed and bus voltage during operation, preparing to switch the generator to motoring mode at the first sign that discharge is needed. This preliminary monitoring and readiness to act ensures that when discharge becomes necessary, the system responds immediately, minimizing wait time before maintenance can begin
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
Significantly reduces downtime for repairs and maintenance by quickly discharging electrical buses using existing components, enhancing safety by avoiding bleeder resistor failures.
Implementation Method 1
switches the generator into a motoring mode if the immediate speed of the engine falls below the speed threshold and the immediate voltage of the common bus exceeds the voltage threshold so as to partially discharge excess voltage from the common bus
Implementation Method 2
enabling one or more of the generator, the motor and the auxiliary devices if the engine speed falls below the first threshold and the voltage exceeds the second threshold so as to discharge voltage from the common bus
Data Source
AI summary
A method of actively discharging a common bus (116) of a machine (100) having an engine (102), a generator (112), a traction motor (124) and one or more auxiliary devices (126) is provided. The method may monitor a speed of the engine (102) with respect to a first threshold, monitor a voltage of the common bus (116) with respect to a second threshold, and enable one or more of the generator (112), the motor (124) and the auxiliary devices (126) if the engine speed falls below the first threshold and the voltage exceeds the second threshold so as to discharge voltage from the common bus (116).