Alternator Progressive Charge Control for Engine Stall Prevention
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Solution Overview
Problem
The progressive charging function in motor vehicle alternators can cause the combustion engine to stall due to sudden variations in torque and voltage during changes in electrical load, particularly when the alternator transitions from a higher speed to a low speed regime, and existing solutions fail to adequately manage periodic load variations which can lead to visual disturbances in headlights.
Innovation Solution
A method and alternator design that updates the progressive charge return signal to indicate a maximum excitation current value equal to the stabilized value when the alternator returns to a low speed regime, and adjusts the duty cycle of the excitation current to prevent sudden torque increases, ensuring a progressive increase in electrical load handling capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the progressive charge function is activated to limit sudden torque variations, then engine stalling is prevented, but significant voltage variations occur during load changes
Solution Approach 1:
The patent applies preliminary action by detecting periodic load variations in advance and adjusting the progressive charge return signal accordingly. Before the periodic variations cause voltage fluctuations, the control system modifies the excitation current progression to compensate, thereby preventing both engine stalling and voltage instability during hazard light operation
Solution Approach 2:
The patent implements feedback by continuously monitoring the alternator's electrical load and voltage output, then adjusting the progressive charge return signal based on detected periodic variations. This closed-loop control enables the system to maintain voltage stability while preventing engine stalling by dynamically adapting the excitation current progression to actual operating conditions
2Power
If the excitation current duty cycle is rapidly increased to meet heavy electrical load demand, then electrical power supply is improved, but the combustion engine may stall due to sudden torque increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and limiting the maximum rate of change of the excitation current duty cycle before heavy load demands occur. The progressive charge return signal establishes advance constraints on how quickly the duty cycle can increase, ensuring that electrical power supply responds adequately to load demands without causing sudden torque spikes that would stall the engine
Solution Approach 2:
The patent implements dynamics by making the excitation current control adaptive to engine operating conditions. The progressive charge function dynamically adjusts the duty cycle progression rate based on alternator speed and engine load characteristics, enabling the system to optimize the balance between electrical power supply capability and engine stability across varying operating conditions
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 approach prevents engine stalling by ensuring a smooth transition of electrical load handling, reducing the risk of sudden torque increases and minimizing voltage fluctuations, thereby maintaining engine stability and preventing visual disturbances in headlights.
Implementation Method 1
an alternator (3) for a motor vehicle comprising a stator, a rotor provided with an excitation winding, voltage regulation means (32) acting on an excitation current supplied to said excitation winding to regulate an output voltage of said alternator
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
The method involves determining maximum mechanical torque at which an alternator is deducted on a thermal engine of a motor vehicle. Maximum torque is determined according to speed of rotation of the alternator. Progressive charge is controlled by a progressive charge control unit comprising a progressive charge return signal indicating a maximum value at which excitation current is reached. The return signal is updated when excitation current attains a stabilized value so as to indicate a maximum current value of excitation current which is equal to the stabilized value. An independent claim is also included for an alternator comprising a stator.