Transformer-Based Cell Balance Circuit for Voltage Equalization
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Solution Overview
Problem
Conventional cell balance circuits for rechargeable batteries face issues with accurate voltage equalization, especially when batteries are discharged, and require costly and bulky monitoring systems, leading to potential battery deterioration due to inadequate voltage stabilization.
Innovation Solution
A cell balance circuit utilizing a transformer with a primary and secondary winding, along with a switching unit comprising multiple switches, to alternately apply charge voltages between batteries, ensuring precise voltage equalization without the need for diodes or extensive monitoring, thereby stabilizing battery voltage during both charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resistor is connected in parallel to each rechargeable battery to equalize charge voltages, then voltage equalization is achieved, but power loss increases due to discharging via resistors
Solution Approach 1:
The patent replaces the passive resistor-based voltage equalization system with an active transformer-based system. The transformer couples multiple battery strings magnetically, allowing voltage equalization through electromagnetic induction rather than resistive dissipation. This substitution eliminates the need for power-dissipating resistors while achieving the same voltage balancing function.
Solution Approach 2:
The patent employs periodic switching of transistors to control the flow of current through the transformer windings. By alternately switching transistors in different battery strings, the system creates periodic current pulses that transfer charge between batteries through the transformer coupling, achieving voltage equalization without continuous power loss.
2Measurement precision
If monitoring circuits are added to monitor charge voltages of multiple rechargeable batteries, then voltage equalization accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines the voltage detection function with the control function in an integrated manner. The control unit that manages transistor switching also performs voltage detection and comparison, eliminating the need for separate monitoring circuits for each battery. This merging of functions reduces device complexity while maintaining accurate voltage equalization.
Solution Approach 2:
The control unit autonomously performs voltage detection, comparison, and switching control without requiring external monitoring systems. The system self-regulates by continuously detecting voltage differences and automatically adjusting current distribution through transistor switching, making the monitoring function inherent to the control mechanism rather than a separate added component.
3Ease of operation
If voltage equalization is performed only after voltage differences occur, then simple circuit operation is maintained, but battery deterioration occurs due to delayed balancing
Solution Approach 1:
The patent implements continuous voltage equalization through ongoing transistor switching and magnetic coupling. Rather than waiting for voltage differences to develop, the system continuously adjusts current distribution between battery strings, maintaining voltage balance proactively. This continuous action prevents voltage imbalances from developing to dangerous levels, thereby extending battery lifespan while maintaining operational simplicity.
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 precise voltage equalization across rechargeable batteries during both charging and discharging, reduces power loss, and prevents battery deterioration, while being compact and cost-effective by eliminating the need for diodes and extensive monitoring systems.
Implementation Method 1
a transformer (which corresponds to the transformer T shown in FIG. 5, for example) comprising a primary winding (which corresponds to the primary winding Wa shown in FIG. 5, for example) arranged so as to form a set with the first rechargeable battery and a secondary winding (which corresponds to the secondary winding Wb shown in FIG. 5, for example) arranged so as to form a set with the second rechargeable battery
Data Source
AI summary
To provide a cell balance circuit and a cell balance apparatus with a low cost and with a compact size, and configured to equalize the charge voltages of rechargeable batteries when the rechargeable batteries are charged or discharged, while suppressing deterioration of the rechargeable batteries. A cell balance circuit AA includes a transformer T, a switch SW1 arranged so as to form a set with a rechargeable battery BT1, and a switch SW2 arranged so as to form a set with a rechargeable battery BT2. The transformer T includes a primary winding Wa arranged so as to form a set with the rechargeable battery BT1, and a secondary winding Wb arranged so as to form a set with the rechargeable battery BT2. When the rechargeable batteries BT1 and BT2 are charged or discharged, the cell balance circuit AA synchronously controls the switches SW1 and SW2.