Alternator Voltage Control for Regenerative Charging Efficiency
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Solution Overview
Problem
Conventional charge control technologies for secondary batteries in vehicles result in inefficient regenerative charging due to calculation errors and increased costs from using multiple electric power storage devices, leading to wasted energy and higher fuel consumption.
Innovation Solution
A charge control device that calculates the current state of charge of a secondary battery using charge and discharge currents and terminal voltage, detects vehicle deceleration to set alternator voltage higher for regenerative charging, and adjusts voltage based on threshold values to maintain a low state of charge, optimizing charging efficiency and reducing costs by using a single secondary battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the secondary battery is operated at a high state of charge to ensure sufficient power storage capacity, then the reliability of power supply is improved, but the charging efficiency decreases because the charge current the battery can accept decreases
Solution Approach 1:
The patent dynamically adjusts the voltage generated by the alternator based on the vehicle's operating state (deceleration detection) and the battery's state of charge. During deceleration, the alternator voltage is set higher than the battery terminal voltage to enable regenerative charging. This dynamic control allows the system to optimize charging efficiency at different SOC levels while maintaining sufficient power storage capacity, resolving the contradiction between reliability and charging efficiency.
2Ease of operation
If conventional charge control methods are used that integrate charge current to estimate SOC, then the measurement simplicity is improved, but the measurement precision deteriorates due to accumulation of calculation errors
Solution Approach 1:
The patent employs a feedback mechanism where the calculated SOC is continuously used to adjust the alternator's voltage output. The control device monitors the battery's terminal voltage and charge/discharge currents, calculates the SOC, and uses this information to regulate alternator voltage. This closed-loop feedback system corrects estimation errors in real-time, improving SOC measurement precision while maintaining the simplicity of current integration methods.
3Productivity
If two electric power storage devices are used to perform regenerative charging, then the charging efficiency is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent makes the single secondary battery perform multiple functions by dynamically adjusting the alternator's voltage. The battery serves both as the primary power storage device and as the regenerative charging target. By controlling the alternator voltage to be higher than the battery terminal voltage during deceleration, the system enables regenerative charging without requiring a second power storage device, thus maintaining charging efficiency while reducing device complexity and cost.
4Adaptability or versatility
If two electric power storage devices with different voltages are used, then the adaptability to different power storage requirements is improved, but the device complexity increases due to the requirement of a DC/DC converter
Solution Approach 1:
The patent extracts and eliminates the DC/DC converter from the system by using a single secondary battery for both power storage and regenerative charging. The alternator, which already generates variable voltage, is controlled to directly charge the battery by adjusting its output voltage based on the battery's terminal voltage and SOC. This removes the need for an additional voltage conversion device, reducing system complexity while maintaining adaptability through voltage control.
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
The solution enables efficient regenerative and normal charging of secondary batteries, improving fuel consumption and reducing production costs by maintaining a low state of charge and utilizing a hybrid battery with a capacitor for enhanced charging efficiency.
Implementation Method 1
engine power drives an alternator (a generator) to generate electric power that is used to charge a secondary battery
Implementation Method 2
The electric power stored in the secondary battery is then used to drive various loads
Implementation Method 3
technologies for using the alternator to convert the kinetic energy of the vehicle to electrical energy as the vehicle is decelerating
Data Source
AI summary
To efficiently control charging and regenerative control for a secondary battery. A charge control device, including: a calculation unit (voltage sensor (11), current sensor (12), and control unit (10)) that calculates a state of charge of the secondary battery; a detection unit (vehicle state detection unit (20)) that detects a traveling state of the vehicle; and a control unit (control unit (10)) that, when it is detected that the vehicle is decelerating, sets a voltage generated by an alternator higher than the terminal voltage of the secondary battery in order to regeneratively charge the secondary battery, that, when it is detected that that the vehicle is not decelerating, sets the voltage generated by the alternator lower than the terminal voltage of the secondary battery when a state of charge is greater than a prescribed second threshold value, and that sets the voltage generated by the alternator higher than the terminal voltage of the secondary battery when the state of charge is less than a prescribed first threshold value. The second threshold value is greater than the first threshold value, and the first threshold value and the second threshold value are set within a low SOC region.