Battery Equalization Device with Dynamic Discharge and Charge Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing equalization devices for hybrid electric vehicle batteries face challenges in achieving rapid and accurate voltage equalization, with discharge-type devices wasting capacity and charge pump types being slow due to limitations in charge amount and requiring stable voltage conditions.
Innovation Solution
The proposed solution employs a combination of discharge resistors and charging capacitors to rapidly reduce voltage variations, allowing for high-accuracy equalization during both stable and unstable voltage conditions, and enables equalization during vehicle operation by selectively using discharge resistors or charging capacitors based on voltage thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If discharge resistors are used to equalize unit cells by discharging, then equalization can be performed during vehicle operation, but battery capacity is wasted
Solution Approach 1:
The patent combines both discharge resistors and charging capacitors in the equalization device. Discharge resistors are used to rapidly reduce voltage variations during vehicle operation, while charging capacitors are used to precisely equalize voltages when the vehicle is stopped, thereby achieving both rapid equalization during operation and energy-efficient equalization when stopped.
Solution Approach 2:
The patent dynamically selects the equalization method based on vehicle operation state. During vehicle operation, discharge-based equalization is performed; during vehicle stop, charge-based equalization is performed. This dynamic switching optimizes both equalization speed and energy efficiency.
2Measurement precision
If charge pump type equalization is used with capacitors, then high precision equalization is achieved, but equalization speed is slow when voltage variation is large
Solution Approach 1:
The patent applies preliminary discharge action to reduce large voltage variations before applying precise charge pump equalization. By first using discharge resistors to bring voltages closer together, the subsequent capacitor-based equalization requires fewer charge/discharge cycles, thereby achieving both speed and precision.
Solution Approach 2:
The patent uses discharge resistors to perform partial equalization (reducing large voltage differences) before the charging capacitors complete the precise equalization. This two-stage approach divides the equalization task into coarse and fine adjustments.
3Measurement precision
If equalization is performed only when vehicle is stopped and voltage is stable, then equalization accuracy is maintained, but equalization cannot be performed during vehicle operation
Solution Approach 1:
The patent applies different equalization methods to different operational conditions: discharge-based equalization for vehicle operation conditions and charge-based equalization for stopped vehicle conditions. This localized approach allows the system to adapt to varying operational requirements while maintaining effectiveness in each context.
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 enables rapid and accurate equalization of battery voltages without capacity waste, allowing for efficient energy supply and regeneration, even during vehicle operation, by using discharge resistors for high variations and charging capacitors for precise control.
Implementation Method 1
discharges a unit cell having the highest both-end voltage with the use of a resistor
Implementation Method 2
sequentially and periodically connects one capacity to both ends of each unit cell thereby moving an electric charge from a unit cell having a high both-end voltage to a unit cell having a low both-end voltage through the capacitor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A microcomputer (3) finds a variation in respective unit cells (CL1 to CLn) based on an output from a voltage detection circuit (21), and executes equalization by controlling FETs (Q11 to Q1n) and connecting unit cells having high both-end voltages in the unit cells (CL1 to CLn) to discharge resistors (Rd1 to Rdn) to perform discharging when the variation in both-end voltages of the unit cells (CL1 to CLn) is greater than or equal to a prescribed value, or executes the equalization by controlling FET pairs (51 to 5n) and sequentially connecting charging capacitors (C1 to cn-1) to the respective unit cells (CL1 to CLn) when the variation is smaller than the prescribed value.