Parallel Battery Connection Voltage Differential Control
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Solution Overview
Problem
The challenge lies in connecting electrical accumulators with different open-circuit voltages in parallel while minimizing stress on the switches and preventing or reducing charge equalization, which often results in high compensating currents and power losses.
Innovation Solution
A method and circuit that control the connection of electrical storage devices by establishing or interrupting the electrical connection based on the voltage difference between the connected and non-connected devices, using switches to manage the parallel connection and disconnection, ensuring that charge is only removed or supplied from the device with the higher no-load voltage when the voltage difference meets specific conditions, thereby minimizing power losses and stress on the switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If several batteries are connected in series to increase energy content, then the energy capacity increases, but the system voltage increases resulting in higher requirements for insulation and creepage and clearance distances
Solution Approach 1:
The battery system is divided into multiple individual battery units, each with its own insulation system designed for its specific voltage level. This segmentation allows each battery to maintain appropriate insulation without requiring the entire system to be designed for the maximum series voltage, thus reducing overall insulation complexity while maintaining energy capacity.
2Quantity of substance
If several batteries are connected in parallel to increase energy content, then the energy content increases without increasing system voltage, but the equalizing current causes turn-on losses and switching power loss that erodes the switches
Solution Approach 1:
A precharge resistor is connected in parallel with each battery switch to equalize voltages before the switch closes. This preliminary action prevents large equalizing currents from flowing through the switch at the moment of closing, thereby eliminating turn-on losses and preventing switch erosion while still allowing parallel connection to increase energy capacity.
Solution Approach 2:
The precharge resistor acts as an intermediary element that temporarily handles the voltage equalization process between batteries before the main switch closes. This mediator component protects the switch from direct exposure to high equalizing currents, reducing power loss and extending switch life while maintaining the parallel connection configuration.
3Adaptability or versatility
If accumulators with different voltages are connected in parallel, then charge equalization occurs, but high compensating currents flow causing power losses and switch stress
Solution Approach 1:
The precharge resistor equalizes the voltages of accumulators before they are connected in parallel by closing the switch. This preliminary voltage equalization prevents large compensating currents from flowing after connection, reducing power losses and switch stress while maintaining the ability to connect accumulators with initially different voltages in parallel.
Solution Approach 2:
The precharge resistor serves as an intermediary that facilitates safe parallel connection of accumulators with different voltages. It provides a controlled path for voltage equalization current, preventing direct high-current flow through the main switch and reducing harmful effects while enabling versatile parallel connections.
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 approach effectively reduces the stress on switches and minimizes power losses during parallel connection of electrical storage devices, allowing for efficient energy distribution with minimal interruption in power draw and reduced wear on the switches.
Implementation Method 1
The level of current flow is defined by the voltage difference between the two storage devices and the resistor in series
Implementation Method 2
a first measuring device for detecting a voltage drop across connection terminals of the first storage device and a second measuring device for detecting a no-load voltage of the second storage device
Implementation Method 3
the control unit controls the switch to close or open it depending on whether a switch-on or switch-off condition is met
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The first and second electrical storage devices (1,2) are connected to connecting terminals (Ke), so that electrical connection between storage devices and connecting terminals is establishable or interruptible by switches (S1,S2). The connection between first device and terminals is established, and connection between second device and terminals is interrupted. The connection between second device and terminals is established if difference between terminal voltage of first device and no-load voltage (VBat2) of second storage device is less than predefined differential add-on voltage. An independent claim is included for circuit of electrical storage devices.