Fuel Cell Battery Charge Control via Dynamic PWM
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Solution Overview
Problem
Fuel cell systems face challenges in providing transient high-power energy and maintaining stable power output due to fuel concentration decay and load variations, leading to excessive charging currents and voltage overcharge during battery charging.
Innovation Solution
A charge-controlling system using a bidirectional converter with a feedback circuit and PWM generator, where the switch unit is controlled based on actual feedback signals and saturation voltage to regulate charging, preventing excessive initial charging currents and voltage overcharge by stopping charging when the voltage exceeds the battery's saturation point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If constant-voltage charging is used, then charging speed is improved, but excessively large charging current damages the secondary cell set
Solution Approach 1:
The patent applies dynamics by transitioning from static constant-voltage charging to dynamic charging control. The charging voltage is dynamically adjusted based on the battery's state of charge: starting at a lower voltage to limit initial current, then gradually increasing to maintain optimal charging current throughout the charging process, thereby preventing current damage while maintaining charging speed.
Solution Approach 2:
The patent changes the charging voltage parameter dynamically during the charging process. Instead of maintaining a fixed high voltage, the system adjusts the voltage parameter according to the battery's charging stage, using lower voltage at the beginning to limit current and higher voltage later to maintain charging efficiency, thus resolving the contradiction between charging speed and current control.
2Object-affected harmful factors
If constant-current charging is used, then charging current is controlled, but charging time becomes excessively long
Solution Approach 1:
The patent resolves this contradiction by making the charging current dynamic rather than constant. The system uses higher charging current when the battery voltage is low (early stage) and reduces current as voltage increases (late stage), thereby significantly reducing total charging time while still preventing voltage overcharge and maintaining current control throughout the process.
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 reduces initial charging currents and prevents voltage overcharge, ensuring stable and efficient power output by dynamically adjusting the charging process based on real-time feedback and battery saturation levels.
Implementation Method 1
a bidirectional converter electrically connected between the fuel-cell-based power supply and the regulated battery
Implementation Method 2
a feedback circuit configured to generate a feedback signal corresponding to an output voltage of the bidirectional converter
Implementation Method 3
a PWM generator electrically connected to the voltage controller so as to generate a PWM signal according to the control voltage
Implementation Method 4
a fuel cell is a cell that converts chemical energy into an electric output by means of an electrochemical reaction
Implementation Method 5
the fuel is decomposed into hydrogen ions and electrons at the anode, and the hydrogen ions are transferred to the cathode from the anode through a proton exchange membrane
Data Source
AI summary
A charge-controlling system and a method therefor are applicable to a backup power system having a fuel-cell-based power supply and a battery. The charge-controlling system includes a bidirectional converter, a feedback circuit, a voltage controller, a PWM generator, a switch unit and an over-charging protection circuit. The feedback circuit generates a feedback signal corresponding to an output voltage of the bidirectional converter. The voltage controller generates a control voltage according to the feedback signal and a constant voltage, such that the PWM generator generates a PWM signal based on the control voltage. The over-charging protection circuit controls operation of the switch unit according to the feedback signal and a saturation voltage of the battery. When the switch unit electrically connects the bidirectional converter and the PWM generator, the bidirectional converter charges the battery with the power generated by the fuel-cell-based power supply according to the PWM signal.