Battery Equalization Circuit Using DC-DC Converter
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Solution Overview
Problem
Existing power supply devices with serially connected batteries face challenges in balancing battery voltages and capacities due to manufacturing variations, leading to uneven charging and discharging, which results in increased heat generation and power consumption during equalization, making it difficult to quickly and efficiently equalize battery properties.
Innovation Solution
A power supply device with a series battery group divided into cell blocks, each equipped with a cell block equalizing circuit that includes a DC/DC converter, output control switches, and a switching control circuit, allowing for active equalization of battery properties by charging or discharging within each block, reducing the amount of capacity to be discharged and minimizing heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a discharging resistor is used to discharge high-voltage batteries for equalization, then the voltage unbalance among batteries is eliminated, but the heat generation and power consumption increase significantly
Solution Approach 1:
Instead of discharging high-voltage batteries through resistors (conventional method), the patent inverts the approach by using low-voltage batteries as discharge sources and charging high-voltage batteries. This is achieved through a DC-DC converter that enables bidirectional energy transfer, transforming the equalization process from energy-dissipating to energy-reusable.
Solution Approach 2:
The patent converts the harmful effect of voltage unbalance into a beneficial energy transfer opportunity. By detecting voltage differences and using the DC-DC converter to transfer energy from low-voltage to high-voltage batteries, the system turns the problem of unbalance into an opportunity for efficient energy redistribution without significant heat loss.
2Loss of time
If a small discharging resistor is used to quickly equalize battery voltages, then the equalization time is reduced, but the heat generation and power consumption remain high
Solution Approach 1:
The patent inverts the conventional equalization logic by preventing the need for high-power discharging. Instead of quickly dumping energy from high-voltage batteries, the system uses the DC-DC converter to efficiently transfer energy from low-voltage batteries, naturally equalizing voltages without requiring high-power components that generate excessive heat.
3Productivity
If high-power discharging resistors are mounted on the circuit board, then the equalization speed increases, but the circuit board size and complexity increase
Solution Approach 1:
The patent eliminates the need for high-power discharging resistors by inverting the equalization approach. The DC-DC converter enables energy transfer from low-voltage to high-voltage batteries, achieving equalization without requiring large, high-power components on the circuit board, thus maintaining compact design while preserving equalization functionality.
Solution Approach 2:
The patent replaces the passive resistor-based discharge mechanism with an active electronic conversion system. The DC-DC converter uses electronic switching and electromagnetic induction to transfer energy efficiently, substituting the need for large physical resistors with a more compact and controllable electronic system.
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 solution enables efficient and rapid equalization of battery properties across the entire power supply device, reducing power consumption and heat generation, while allowing for smaller and more efficient circuitry, as batteries with lower capacity are actively charged from others, thereby balancing voltages and capacities effectively.
Implementation Method 1
The DC/DC converter includes a transformer 21. The primary-side of the transformer 21 is connected through a primary-side switching element 41 to the series battery group 10
Data Source
AI summary
A transformer 21 includes charging secondary winding lines 24 that can charge batteries 11 composing a corresponding cell block, and a discharging secondary winding line 26 that can discharge the corresponding cell block. Each of the charging secondary winding lines 24 is connected to corresponding one of the batteries 11 through corresponding one of secondary-side rectification output circuits 25 and corresponding one of output control switches 22. The discharging secondary winding line 26 is connected to a block discharging circuit through a block discharging switch 28. A switching control circuit 23 controls the block discharging switch 28. The switching control circuit 23 controls the output control switches 22 so that the electrical properties of the batteries 11 in the cell block are equalized. In addition, the switching control circuits 23 control the block discharging switches 28 so that the electrical properties of the batteries among the cell blocks are equalized.