Onboard Battery Charging Control for Accurate SOC Estimation
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Solution Overview
Problem
Existing charging technologies for onboard batteries in vehicles suffer from errors in state of charge (SOC) estimation due to polarization effects, leading to inaccurate charging termination and potential undercharging or overcharging.
Innovation Solution
A control device is employed to suspend charging at prescribed timings, discharge onboard battery power, measure voltage after discharge, and derive SOC based on corrected measurements to reduce polarization effects, followed by topping charging to ensure accurate SOC estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If charging is performed continuously without suspension, then charging speed is improved, but measurement precision of SOC deteriorates due to polarization effects
Solution Approach 1:
The charging process is performed in periodic cycles with alternating charging and suspension phases. During charging, power is supplied to the battery; during suspension, charging is paused to allow polarization to subside and enable accurate voltage measurement. This periodic alternation maintains high overall charging speed while ensuring periodic accuracy checks to correct SOC estimation errors.
Solution Approach 2:
Before performing voltage measurement for SOC calculation, the system preliminarily suspends charging to eliminate polarization effects. This preliminary suspension action ensures that when voltage measurement occurs, the battery voltage reflects the true state of charge without polarization distortion, thereby improving measurement precision before the actual SOC determination is made.
2Measurement precision
If charging is suspended frequently to measure voltage, then measurement precision is improved, but productivity deteriorates due to charging time loss
Solution Approach 1:
Instead of suspending charging completely and frequently, the system applies partial suspension action by pausing charging only briefly at strategically determined moments. The suspension duration is optimized to be just sufficient for polarization to subside to acceptable levels, avoiding excessive suspension time that would reduce charging productivity. This partial action approach achieves adequate measurement precision without overly sacrificing charging speed.
Solution Approach 2:
The system uses feedback from voltage measurements taken during suspension periods to continuously monitor and correct SOC estimation accuracy. This feedback mechanism allows the system to adaptively adjust charging parameters and suspension timing, ensuring that suspension occurs only when necessary to maintain accuracy, thereby minimizing productivity loss while preserving measurement precision.
3Productivity
If voltage is measured during charging, then productivity is improved, but measurement precision deteriorates due to polarization voltage
Solution Approach 1:
The suspension phase acts as an intermediary state between charging and voltage measurement. During this intermediate phase, charging is paused and the battery is allowed to settle, eliminating polarization effects. This intermediary suspension period enables accurate voltage measurement to occur without the interference of polarization voltage, while the overall charging process maintains high efficiency through minimal suspension duration.
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 significantly reduces errors in SOC estimation by correcting measurement voltages for polarization, ensuring accurate charging termination and maintaining desired SOC levels.
Implementation Method 1
The onboard battery is configured to be electrically coupled to the charging port. The control device is configured to perform charging of the onboard battery with power supplied through the charging port.
Implementation Method 2
The process includes measuring a voltage of the onboard battery after the discharging of the onboard battery. The process includes deriving a state of charge of the onboard battery, based on the measured voltage of the onboard battery.
Data Source
AI summary
A charging device includes a charging port, an onboard battery, and a control device. The charging port can be electrically coupled to an external power source. The onboard battery can be electrically coupled to the charging port. The control device is configured to charge the onboard battery with power supplied through the charging port. The control device includes one or more processors and one or more memories. The one or more processors are configured to execute a process including suspending the charging of the onboard battery at a prescribed timing during the charging of the onboard battery, discharging at least some of the power in the onboard battery from the onboard battery when the charging of the onboard battery is suspended, measuring a voltage of the onboard battery after the discharging, and deriving a state of charge of the onboard battery, based on the measured voltage of the onboard battery.