Hybrid Fuel Cell Battery Power Management Circuit
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Solution Overview
Problem
Existing hybrid fuel cell/battery systems face inefficiencies in power management and battery charging due to the need for DC/DC converters, which result in significant weight, volume, and efficiency losses, as well as unsafe and unreliable charging methods.
Innovation Solution
A circuit comprising a buck-boost converter and direct charge circuit, with a network that passively switches between the two based on voltage levels, eliminating the need for a conventional DC/DC converter and allowing the fuel cell stack to match the battery's voltage/current relationship, enabling efficient power sharing between the fuel cell and battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a DC/DC converter is used to manage voltages between battery and fuel cell, then voltage matching is achieved, but system weight, volume, and efficiency deteriorate
Solution Approach 1:
The patent extracts and eliminates the DC/DC converter component from the hybrid system by directly matching the fuel cell stack voltage characteristics to the battery voltage characteristics through proper sizing and configuration, thereby removing the source of weight, volume, and efficiency losses while maintaining voltage compatibility
2Adaptability or versatility
If a buck DC/DC converter is used for battery charging, then voltage reduction is achieved, but charging efficiency deteriorates due to losses
Solution Approach 1:
The patent removes the buck DC/DC converter from the charging system and instead achieves voltage reduction through direct electrical connection between the fuel cell stack and battery, eliminating converter losses and achieving near-100% charging efficiency while maintaining proper voltage levels through fuel cell stack configuration
Solution Approach 2:
The fuel cell stack is designed to naturally provide voltage compatible with battery charging requirements through proper sizing and configuration, eliminating the need for external voltage conversion equipment and enabling direct efficient charging
3Adaptability or versatility
If a buck-boost DC/DC converter is used for battery charging, then voltage flexibility is achieved, but energy loss increases when high power is required
Solution Approach 1:
The patent eliminates the buck-boost DC/DC converter by designing the fuel cell stack with voltage characteristics that naturally match battery charging requirements across the operating range, removing the source of energy losses while maintaining voltage flexibility through proper stack configuration
Solution Approach 2:
The fuel cell stack is oversized relative to the battery capacity to ensure that the stack voltage remains above the battery charging voltage across the entire operating range, eliminating the need for voltage boosting while providing excess voltage capability that simplifies the charging architecture
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 solution reduces system weight and complexity, increases charging efficiency and safety, and allows power to be drawn from the fuel cell up to its rated power, with additional power from the battery, effectively managing power across the full voltage range.
Implementation Method 1
The reactants, through the electrolyte (membrane), react indirectly with each other generating an electrical voltage between the cathode and anode
Implementation Method 2
a battery having a rated power greater than the rated power of the fuel cell stack
Data Source
AI summary
Disclosed herein is a circuit for passively managing power between a fuel cell stack and a battery in a hybrid system. The circuit includes a buck-boost converter circuit, a direct charge circuit; and a network which interconnects them. The network is configured so that in response to a voltage level in the network being lower than or equal to a maximum battery charge voltage, the battery is charged via the direct charge circuit; and in response to another voltage level in the network which is higher than the maximum battery charge voltage, the battery is charged via the buck-boost converter circuit. Also disclosed is a device incorporating the circuit and a method of passively managing power.