Battery Balancing Circuit With Indirect Feedback and Shared Sampling
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Solution Overview
Problem
Current electrochemical cell balancing methods, particularly active balancing solutions, are complex and costly, with passive balancing consuming energy and lacking efficient energy utilization, and existing active balancing solutions are incompatible with cell sampling functions, leading to circuit complexity and continuous charging issues.
Innovation Solution
A battery electrical energy balancing circuit with a controller, battery control switches, a filter capacitor control unit, and a sampling unit, which achieves active balancing and battery sampling without affecting each other, using a single primary-side winding and double secondary-side windings with reduced high-frequency switches, and indirect energy feedback to prevent continuous charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive balancing is used with resistors to consume energy for voltage balancing, then the circuit structure is simple and costs are low, but energy utilization efficiency deteriorates due to energy consumption
Solution Approach 1:
The patent introduces a transformer as an intermediary device between batteries to enable indirect energy transfer. The transformer couples high-voltage and low-voltage batteries through magnetic fields, allowing energy to be transferred without direct electrical connection. This resolves the contradiction by providing a balancing mechanism that avoids resistor energy consumption while maintaining circuit simplicity through the use of a single shared transformer.
2Loss of energy
If active balancing is used to transfer energy from high-voltage to low-voltage batteries, then energy utilization efficiency is improved, but device complexity increases due to more components and higher costs
Solution Approach 1:
The patent implements a universal balancing circuit where a single transformer and controller can balance any battery in the series string. The controller selectively connects different batteries to the transformer primary or secondary sides based on which batteries need balancing. This multi-functional design eliminates the need for separate balancing circuits for each battery pair, significantly reducing component count and complexity while maintaining efficient energy transfer.
Solution Approach 2:
The patent changes the operating parameters of the transformer dynamically by switching which batteries are connected to different terminals. The controller adjusts the connection configuration based on real-time battery voltage measurements, enabling the same hardware to adapt to different balancing scenarios. This parameter-based control approach avoids the need for complex dedicated circuits for each balancing case.
3Loss of energy
If existing active balancing solutions are implemented, then energy transfer is achieved, but compatibility with battery sampling function deteriorates leading to circuit complexity
Solution Approach 1:
The patent merges the balancing function and sampling function into a single integrated circuit path. The same transformer and control switches used for balancing are also utilized for voltage sampling. During sampling mode, the controller configures the switches to connect the transformer windings in a manner that allows voltage measurement without affecting the sampling accuracy. This consolidation eliminates the need for separate sampling circuits, reducing overall complexity while maintaining both functions.
4Adaptability or versatility
If transformer isolation is used for bidirectional energy conversion, then energy transfer flexibility is improved, but device complexity increases due to continuous charging issues when battery is fully charged
Solution Approach 1:
The patent implements a feedback control mechanism where the controller continuously monitors battery voltage during balancing operations. When a battery reaches its full charge voltage threshold, the controller automatically stops the energy transfer to that battery by adjusting the switch configuration. This feedback control prevents overcharging while maintaining the flexibility of bidirectional energy conversion, avoiding the need for complex additional protection circuits.
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 reduces circuit complexity and costs while achieving efficient energy utilization by reusing battery control switches for both active balancing and sampling, and prevents continuous charging by indirect energy feedback, simplifying the battery management system.
Implementation Method 1
The transformer isolation uses an isolation transformer to achieve bidirectional conversion of energy. When a voltage of an electrochemical cell is low, energy is supplied from a busbar to the electrochemical cell with a low voltage through a transformer.
Implementation Method 2
The filter capacitor control unit is configured to filter a current input by the balancing unit to the target battery.
Data Source
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AI summary
Provided are a battery electrical energy balancing circuit and method and an energy storage system, including a controller, N battery control switches, a filter capacitor control unit, a balancing unit, and a sampling circuit. The balancing unit charges/discharges a target battery, and the sampling unit detects a voltage of the target battery. The filter capacitor control unit performs filtering. The controller controls a battery control switch connected to the target battery to be closed, to obtain the voltage value of the target battery detected by the sampling unit; or controls the balancing unit to charge/discharge the target battery. The sampling unit and the balancing unit in this application reuse the N battery control switches, to not only achieve an active balancing function but also achieve a battery sampling function, thereby reducing complexity of an electrical energy balancing circuit in a conventional solution. In addition, the power supply is not directly connected to the battery, but instead, is charged indirectly through the balancing unit, so that energy is fed back through an indirect feedback method, thereby resolving a problem of continuous charging when the battery is fully charged.