Engine Idle Speed Control for Alternator Load and Battery SOC
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Solution Overview
Problem
Current engine control systems face challenges in managing engine idle speed effectively when electrical loads are high, leading to increased noise and vibrations due to frequent alternator compressor cycling.
Innovation Solution
A method and system that determine the state of charge (SOC) of a vehicle battery and the maximum output of the alternator at current idle speed, then adjust the engine idle speed based on the load being greater than the alternator's maximum output, thereby optimizing idle speed without unnecessary alternator compressor cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine idle speed is increased to support maximum electrical loads, then the alternator can sustain enough electrical output, but the engine noise and vibrations increase
Solution Approach 1:
The system dynamically adjusts the idle speed threshold parameter based on battery state of charge (SOC). When SOC is high, the threshold is raised, allowing the engine to operate at lower idle speeds and reduce noise/vibrations. When SOC is low, the threshold is lowered, permitting higher idle speeds to ensure adequate electrical output. This parameter adaptation resolves the contradiction by making idle speed adjustment context-dependent rather than fixed.
2Power
If the engine idle speed is increased when A/C compressor is engaged, then the alternator can support the electrical load, but the idle engine speed fluctuates causing unwanted noise and vibrations
Solution Approach 1:
The system performs preliminary assessment of battery SOC before adjusting idle speed in response to A/C compressor engagement. By checking SOC status first, the system determines whether idle speed increase is truly necessary. This preliminary action prevents unnecessary idle speed fluctuations that would occur with traditional systems that always increase idle speed when A/C is engaged, thereby maintaining stability while ensuring power availability when needed.
3Power
If the alternator is required to support maximum electrical loads at normal idle speed, then the electrical system can handle high loads, but the battery may experience low state of charge conditions
Solution Approach 1:
The system continuously monitors battery SOC and uses this feedback to dynamically adjust the idle speed threshold. When SOC drops below a certain level, the system lowers the threshold, allowing the engine to maintain higher idle speeds and generate more electrical power to recharge the battery. This feedback mechanism ensures the battery remains within safe operating parameters while still enabling the alternator to support maximum electrical loads when necessary.
Data Source
AI summary
Systems and methods for controlling engine idle speed based on electrical load are provided. A system includes a logic device configured to perform various operations for controlling an idle speed of an engine. The logic device is configured to determine a state of charge (SOC) of a battery, a maximum output of an alternator at a current idle speed of an engine, and a load on the alternator. The logic device is further configured to initiate an increased idle speed of the engine based on the determined SOC of the battery and based on the load being greater than the maximum output. The logic device is further configured to initiate a decreased idle speed of the engine based on the SOC being less than an SOC threshold. Associated methods are also provided.