Super Capacitor Bank for Battery Load Leveling in Lift Trucks
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Solution Overview
Problem
Existing methods for extending the charge life of electric vehicle batteries, such as opportunity charging and fast charging, are expensive, inefficient, and can lead to battery overheating, which reduces battery life.
Innovation Solution
A method and apparatus using a bank of super capacitors connected between the battery and electrical load, with a controller that measures voltage differences and applies pulse width modulation charging to supplement current draw, reducing battery discharge and extending battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fast charging is used to extend battery charge life, then charging speed is improved, but battery temperature increases causing harmful effects
Solution Approach 1:
A DC-DC converter is introduced as an intermediary device between the charger and the battery. This converter acts as a buffer that manages the charging process, allowing fast charging to occur while controlling the battery temperature through regulated power transfer and thermal management, thus resolving the contradiction between charging speed and temperature control
Solution Approach 2:
The system dynamically changes charging parameters (current, voltage, power levels) based on real-time battery temperature monitoring. When temperature rises during fast charging, the system automatically adjusts parameters to reduce thermal stress, enabling fast charging while preventing harmful temperature increases
2Loss of energy
If opportunity charging is used to extend battery charge life, then energy efficiency is improved, but charging time increases requiring significant waiting period
Solution Approach 1:
The system dynamically adapts the charging rate based on operational conditions and battery state. During opportunity charging events, it can accept higher charging rates when conditions permit, reducing the time penalty while maintaining energy efficiency benefits, thus balancing the trade-off between energy recovery and time loss
3Object-affected harmful factors
If regular battery charger is used to extend battery charge life, then battery temperature is controlled, but charging speed is slow reducing productivity
Solution Approach 1:
The system employs periodic charging cycles that alternate between higher power phases (for speed) and lower power phases (for temperature control). This periodic modulation allows the battery to be charged faster on average while providing thermal management intervals, thus improving productivity without sacrificing temperature 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 effectively extends the usable battery life by reducing the rate of discharge and minimizing battery heating, thereby increasing the time between charges and improving battery longevity.
Implementation Method 1
connecting a bank of super capacitors between an electrical load and the battery supplying power to the load
Implementation Method 2
measuring a battery voltage at the battery, measuring a capacitor voltage indicating the voltage on the bank of super capacitors, A voltage difference is calculated between the battery voltage and the capacitor voltage
Implementation Method 3
the capacitor bank is charged when the voltage difference is greater than a predetermined minimum voltage level by applying a pulse width modulated charging voltage to the super capacitors with a duty cycle of the pulse width modulation being based on the voltage difference
Data Source
Figure 1
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Figure 3A
AI summary
An energy storage module for use in an electric vehicle, such as a lift truck, is disclosed. The energy storage module includes a bank of super capacitors or ultra-capacitors which are connected between the battery and the load. In operation, the energy storage module charges the capacitors, and uses the charged capacitors to level the load on the battery, limiting spikes in current draw, and assuring a substantially smooth discharge profile, wherein the battery discharge is substantially steady state. The energy storage module further includes sensors for determining when the battery and load are connected.