Cooling Fan Duty Control for Battery Cooling and Noise Reduction
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Solution Overview
Problem
Existing cooling fan control systems for vehicles do not precisely control the number of revolutions of the cooling fan, which can lead to inefficient cooling and noise issues due to variations in voltage and operational conditions.
Innovation Solution
A control device that uses a voltage sensor to detect the voltage of a first power storage mechanism and sets a control value to precisely control the number of revolutions of the cooling fan, taking into account the voltage, state of charge, and input/output current of a second power storage mechanism, while also applying feedback control to maintain a predetermined operational state and prevent rapid variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the cooling fan is controlled using a constant duty ratio, then the control system is simple, but the number of revolutions cannot be precisely controlled due to voltage variations
Solution Approach 1:
The control device uses feedback control by detecting the actual number of revolutions of the cooling fan and comparing it with the target number of revolutions. The duty ratio is then adjusted based on the difference between these values to achieve precise control. This feedback mechanism compensates for voltage variations and ensures accurate revolution control.
Solution Approach 2:
The control device changes the duty ratio parameter dynamically based on detected voltage levels and required cooling demand. By adjusting this electrical parameter, the system compensates for voltage fluctuations and maintains precise control over the cooling fan's number of revolutions without requiring complex mechanical modifications.
2Productivity
If the duty ratio is increased to cool the second power storage mechanism faster, then cooling efficiency is improved, but noise audible to passengers increases
Solution Approach 1:
The control device dynamically adjusts the duty ratio based on real-time conditions including voltage levels, temperature requirements, and noise constraints. This dynamic control allows the system to optimize cooling efficiency while maintaining noise levels within acceptable ranges by varying the duty ratio smoothly rather than using fixed high values.
Solution Approach 2:
The control device employs periodic PWM (pulse width modulation) to control the cooling fan operation. This periodic action allows for precise control of the average power delivered to the fan, enabling efficient cooling while reducing noise compared to continuous full-power operation. The periodic switching also helps in smoothing out noise fluctuations.
3Temperature
If the cooling fan operates at high speed to ensure adequate cooling, then temperature control is improved, but energy consumption from the first power storage mechanism increases
Solution Approach 1:
The control device optimizes the duty ratio parameter to achieve the minimum necessary fan speed for adequate cooling. By continuously monitoring temperature requirements and adjusting the duty ratio accordingly, the system avoids unnecessary high-speed operation and reduces energy consumption while maintaining effective temperature control.
Solution Approach 2:
The control device monitors the state of charge and voltage of the first power storage mechanism and automatically adjusts cooling fan operation to match available energy resources. When energy is limited, the system intelligently modulates fan speed to maintain essential cooling while conserving energy, allowing the power storage mechanism to serve its primary function more efficiently.
Data Source
AI summary
A hybrid ECU executes a program including the steps of: setting a fan driving level F for a cooling fan, as based on a high voltage battery's temperature TB, SOC and input and output currents, and a vehicular cabin's internal temperature and background noise; detecting from a signal transmitted from a voltage sensor the voltage of an auxiliary battery serving as a power supply for the cooling fan; and setting a duty command value for the cooling fan from fan driving level F and the auxiliary battery's voltage so that the duty command value is smaller as a voltage of the auxiliary battery is higher.