Active Battery Equalizer Circuit With Shared Transformer Windings
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Solution Overview
Problem
Conventional active equalizer circuits for battery packs are costly and voluminous due to the use of multiple MOSFET switches and isolated drivers, which hinders their widespread adoption in reducing voltage inconsistency among battery cells, thereby affecting the available capacity and cycle life of battery packs.
Innovation Solution
The active equalizer circuit design reduces costs and volume by using a shared secondary winding for multiple battery cells and synchronously driving switching transistors with a multi-port converter, eliminating the need for isolated drivers and power supplies, and employing a buck converter to manage voltage across the battery pack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional active equalizer circuits use multiple MOSFET switches and isolated drivers for each battery cell, then voltage equalization can be achieved, but the circuit cost and volume increase significantly
Solution Approach 1:
The patent merges multiple isolated driver circuits into a single centralized driver that controls all MOSFET switches. The driver circuit is shared across all battery cell pairs, eliminating the need for separate isolated drivers for each cell. This consolidation significantly reduces circuit volume and component count while maintaining the ability to perform voltage equalization across all cells through the shared driver architecture.
Solution Approach 2:
The single driver circuit performs multiple functions by controlling different MOSFET switches for various battery cell pairs. The driver can selectively activate appropriate MOSFETs to equalize voltage between different cell combinations, making the driver universal rather than dedicated to a single cell pair. This multi-functionality reduces the overall number of driver circuits needed.
2Reliability
If conventional active equalizer circuits use one transformer winding per battery cell, then voltage equalization can be performed, but the circuit volume and cost increase
Solution Approach 1:
The patent combines multiple transformer windings into a single shared transformer that serves all battery cell pairs. Instead of having separate transformers or windings for each cell, a single transformer with multiple taps or windings is used to facilitate voltage equalization across all cells. This consolidation dramatically reduces the overall transformer size and circuit volume while maintaining equalization functionality.
Solution Approach 2:
The single transformer performs multiple equalization functions by providing different winding configurations that can equalize voltage between various battery cell pairs. The transformer is designed to be universal, handling equalization for any combination of cells through its multi-functional winding structure, thereby eliminating the need for multiple dedicated transformers.
3Adaptability or versatility
If conventional active equalizer circuits use multiple isolated drivers, then each battery cell can be controlled independently, but the circuit cost increases
Solution Approach 1:
The patent combines multiple isolated driver circuits into a single centralized driver that maintains independent control capability for each battery cell. The single driver uses control signals to selectively activate different MOSFET switches, enabling independent control of voltage equalization for each cell pair. This merging approach reduces cost by eliminating redundant driver components while preserving the adaptability to control individual cells as needed.
Solution Approach 2:
The single driver circuit is designed with universal control capability to manage multiple MOSFET switches across different battery cell pairs. It can adaptively control equalization for any cell combination by selectively activating appropriate switches, maintaining the versatility of independent cell control through a cost-effective single-driver 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 design significantly reduces the volume and cost of the active equalizer circuit while ensuring effective voltage equalization among battery cells, enhancing the available capacity and cycle life of the battery pack by minimizing the number of switching transistors and transformer windings.
Implementation Method 1
the active equalizer circuit comprises at least one or more MOSFET switches, one or more isolated drivers, and one transformer winding for each battery cell
Implementation Method 2
each pair of cells in a string shares a single inductor. Switches permit the single inductor to selectively charge one or the other of the cells
Data Source
Figure 1
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Figure 4a
AI summary
Embodiments of the present invention provide an active equalizer circuit, a battery management system, a power supply system and an electrical equipment. The active equalizer circuit comprises a plurality of switching transistors, a driving transformer, a multi-port converter, a buck converter, and a microcontroller. Each of the switching transistors is coupled to a battery cell in the series battery pack on a one-to-one basis. The multi-port converter comprises an equalizing transformer and a bridge converter, each secondary winding of the bridge converter is coupled to a corresponding plurality of battery cells. The buck converter has an input terminal coupled to an output terminal of the series battery pack and an output terminal coupled to an input terminal of the bridge converter. The microcontroller is configured to output a first control signal to the buck converter, to make the buck converter transform an output voltage of the series battery pack and output the transformed output voltage to the bridge converter, and output a second control signal to the bridge converter, to control an operation state of the bridge converter. According to the embodiments of the present invention, the cost and volume of the active equalizer circuit can be reduced.