FET Switch Parasitic Diode Bidirectional Current Blocking
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Solution Overview
Problem
Existing energy storage module designs require complex and costly switch configurations to achieve bidirectional current blocking and equalization of cell voltages, leading to inefficiencies and increased risk of system failure.
Innovation Solution
A series-parallel reconfigurable cell voltage equalization circuit using field-effect transistors (FETs) with a simplified switch configuration, where each switch group consists of FETs arranged to allow bidirectional current flow in one polarity during ON states and block it in the other polarity during OFF states, reducing the number of elements and circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex switch configurations are used to achieve bidirectional current blocking, then reliability of voltage equalization is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines bidirectional current blocking functionality into a single FET switch by leveraging the parasitic diode inherent in the FET structure. Instead of using separate switches for each direction, the invention merges the blocking function into one component, thereby reducing device complexity while maintaining voltage equalization reliability.
Solution Approach 2:
The FET switch utilizes its own parasitic diode to achieve bidirectional current blocking without requiring external components or additional circuitry. The parasitic diode, which is an inherent part of the FET structure, automatically provides the blocking function in the reverse direction, making the system self-sufficient and reducing overall complexity.
2Manufacturing precision
If multiple switches are used for bidirectional current blocking, then current control precision is improved, but the number of components and circuit complexity increase
Solution Approach 1:
The patent merges the function of multiple switches into a single FET switch by utilizing the parasitic diode for bidirectional current control. This reduces the quantity of components from multiple switches to just one FET, while maintaining precise current control through the combined action of the FET channel and parasitic diode.
3Reliability
If complex switch configurations are used, then voltage equalization performance is improved, but ease of manufacture deteriorates
Solution Approach 1:
The invention merges multiple switch functions into a single FET component, significantly reducing the number of parts that need to be assembled and wired. This simplification directly improves ease of manufacture while maintaining voltage equalization performance through the efficient use of the FET and its parasitic diode.
Solution Approach 2:
By utilizing the parasitic diode's inherent blocking capability, the circuit eliminates the need for additional blocking components, reducing assembly steps and manufacturing complexity while maintaining the required voltage equalization performance.
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 enables a more efficient and cost-effective cell voltage equalization, reducing the risk of system failure and allowing for a simpler driver circuit configuration, making it suitable for use in uninterruptible power supply systems.
Implementation Method 1
switching is performed between a first connection state as illustrated in FIG. 2 which is to be attained when each of the switches Sa1 to Sa6 making up the first switch group is turned on (i.e., set to an ON state), and a second connection state as illustrated in FIG. 3 which is to be attained when each of the switches Sb1 to Sb6 making up the second switch group is turned on (i.e., set to an ON state)
Implementation Method 2
each of the parallel circuits formed in the first connection state includes a field-effect transistor adapted to avoid blocking a current having one of opposite polarities in the each of the parallel circuits, and a field-effect transistor adapted to avoid blocking a current having the other polarity
Data Source
AI summary
It is an object to provide a circuit for equalizing voltages of energy storage cells, with less number of element and simpler circuit configuration than ever before.A plurality of field-effect transistors are arranged such that each of a plurality of parallel circuits formed, in one of connection states attained by switching of the switches, by connecting in parallel energy storage cells to perform mutual charging and discharging, includes a field-effect transistor adapted to avoid blocking a current having one of opposite polarities in the each of the plurality of parallel circuits, and a field-effect transistor adapted to avoid blocking a current having the other polarity in the each of the plurality of parallel circuits. This makes it possible to perform a voltage equalization operation using a small number of transistors.