Generator Speed Control for Engine Stalling Prevention

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Solution Overview

Problem

Existing power control systems for electro-mechanical power conversion systems, such as those in vehicles and generator sets, face challenges in managing sudden changes in engine speed, which can lead to engine stalling and mechanical load imbalances, as they primarily rely on monitoring electrical loads or torque changes rather than mechanical speed variations.

Innovation Solution

A control device that measures changes in generator or prime mover speed and adjusts the output power accordingly, using a generator speed indicator and output power controller to either reduce or restore power based on speed changes, thereby preventing engine stalling and maintaining efficient power conversion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the system monitors electrical loads or torque changes to manage power, then the control response is delayed, but the engine may stall due to excessive mechanical load

Engineering Contradiction:

Improveengine operation stabilityVSAvoidcontrol response time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces electrical load monitoring and torque change detection with direct mechanical speed measurement using a speed indicator coupled to the engine or generator. This substitution allows the system to detect mechanical load imbalances before they cause stalling, providing earlier warning and enabling preventive action rather than reactive control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs preliminary detection of speed changes that indicate developing load imbalances before the engine actually stalls. By identifying trends in speed variation and comparing them against threshold criteria, the system can take preventive action (such as reducing generator field current) before the critical stalling point is reached, rather than waiting for the stall to occur.

Inventive Principle:

Principle #10Preliminary action

2Power

If the generator output power is increased to meet electrical load demands, then the power supply capacity is improved, but the engine experiences excessive mechanical load

Engineering Contradiction:

Improvegenerator output powerVSAvoidmechanical load on engine

Core Design Contradiction:

PowerVSForce

Solution Approach 1:

The system continuously monitors engine speed or generator speed as feedback regarding the mechanical load state. When speed deviations exceed predetermined thresholds, the controller adjusts the generator field current to reduce mechanical load on the engine, creating a closed-loop feedback system that balances power output with engine capacity.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts generator field current based on real-time speed measurements and changing load conditions. Rather than operating at fixed settings, the controller modulates the field current to optimize the balance between electrical power output and mechanical load on the engine, allowing adaptive response to varying operational demands.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8283797B2Power control system and method

Publication Date: 2012.10.09 NIEHOFF CE & CO

AI summary

This invention discloses a power control system comprising a prime mover and a generator driven by the prime mover. A control device is coupled with the generator to ascertain a change in speed of the generator and vary an output power of the generator according to the change. The control device applies a signal to reduce the generator output power and another signal to restore the generator output power. The power control system may include a transmission, a speed converter, and/or an accessory.