Dual Battery AC Power Supply With Threshold-Based Mode Switching
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Solution Overview
Problem
Existing power supply systems using battery strings are limited to either direct-current (DC) or alternating-current (AC) power output, restricting their application range and efficiency, with no effective method to switch between the two based on demand.
Innovation Solution
A power supply system comprising a first power supply circuit with a DC battery string and an inverter for AC power output, and a second power supply circuit with an AC battery string, controlled by a device that switches between modes to manage power transfer and output AC power efficiently based on current thresholds, utilizing high power density batteries for high-rate and high energy density batteries for low-rate power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a battery string is designed for direct-current power output, then it can provide high power density and efficient high-rate power supply, but it cannot output alternating-current power directly
Solution Approach 1:
The battery string system is designed to perform multiple functions by incorporating both DC battery strings and AC battery strings, allowing the same battery string architecture to serve both DC and AC power supply needs. The control device enables the system to switch between DC output mode and AC output mode, making the battery string universally applicable for different power requirements without requiring separate dedicated systems.
Solution Approach 2:
An inverter is introduced as an intermediary device between the DC battery string and the AC load. The inverter converts DC power from the DC battery string into AC power, enabling the DC battery string to supply AC loads indirectly. This mediator resolves the contradiction by allowing high power density DC batteries to serve AC applications through power conversion.
2Device complexity
If a battery string is designed for alternating-current power output without an inverter, then it can reduce system complexity and cost, but it cannot provide high power density and efficient high-rate power supply
Solution Approach 1:
The battery string system is segmented into functionally distinct DC battery strings and AC battery strings. The AC battery strings are designed to work without inverters for simplified AC power supply, while DC battery strings are reserved for applications requiring high power density. This segmentation allows each subsystem to be optimized for its specific function, reducing overall system complexity while maintaining high power capability where needed.
3Device complexity
If a single battery string is used for both low-rate and high-rate power supply, then it simplifies the system structure, but it cannot optimize battery performance and reduce degradation for each specific application
Solution Approach 1:
Different battery strings are assigned different qualities and characteristics based on their intended use. DC battery strings are optimized for high power density and high-rate discharge applications, while AC battery strings are optimized for lower power density and continuous operation. The control device intelligently selects which battery string to use based on the specific power supply rate requirements, ensuring each battery operates in its optimal performance range and minimizing degradation.
Solution Approach 2:
The system dynamically switches between DC battery strings and AC battery strings based on real-time power supply rate requirements. The control device monitors the power demand and automatically selects the appropriate battery string configuration, transitioning from AC battery string for low-rate supply to DC battery string for high-rate supply, optimizing battery performance and longevity adaptively.
4Power
If the inverter is used for converting DC to AC power, then high power density can be achieved, but the system cannot efficiently handle low-rate power supply and the batteries degrade faster
Solution Approach 1:
The control device implements dynamic mode switching between inverter-based AC output and direct AC battery string output based on the power supply rate. For low-rate power supply, the system uses the AC battery string directly without the inverter, extending battery duration and reducing degradation. For high-rate power supply, the system switches to inverter-based AC output from DC battery strings, maximizing power density. This dynamic adaptation optimizes both power delivery and battery longevity.
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
Enables efficient low-rate and high-rate power supply, reduces battery degradation, and extends power supply duration by using appropriate battery types for each mode, while maintaining high power density and energy density, thus enhancing the system's versatility and cost-effectiveness.
Implementation Method 1
an inverter that converts direct-current power output from the direct-current battery string to alternating-current power
Data Source
AI summary
A power supply system that outputs AC power to an object to which power is to be supplied includes: a first power supply circuit including a DC battery string and an inverter and configured to output first AC power; a second power supply circuit including an AC battery string and configured to output second AC power; and a control device. In the first mode, power is transferred between the object and the second power supply circuit. In the second mode, power is transferred between the object and each of the first and second power supply circuits. The control device starts supplying the second AC power to the object in the first mode, and when a power supply current becomes larger than a first threshold, supply the first and second AC power to the object in the second mode.