Series Battery Voltage Balancing via Selective Discharge
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Solution Overview
Problem
When energy storage devices connected in series exhibit variations in charge capacity, the voltage of the device with a high charge rate can exceed a threshold, leading to malfunctions and potential damage during charging, as the current interrupting device may interrupt charging, causing a sudden voltage increase due to counter electromotive force from inductance components.
Innovation Solution
An energy storage apparatus with a voltage detection unit and a discharge circuit that selectively discharges the energy storage device with the highest voltage, and a control unit that stops charging if the voltage exceeds predetermined thresholds, thereby preventing malfunctions by managing the charge current and voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If energy storage devices are connected in series to obtain predetermined voltage, then the total voltage output is improved, but variations in charge capacity among devices occur due to imbalance in electrical characteristics
Solution Approach 1:
The patent segments the energy storage devices into individual controllable units with separate voltage detection and discharge control. Each device's voltage is monitored independently, and discharge operations are applied selectively to specific devices rather than uniformly to all devices, thereby addressing charge capacity variations while maintaining series connection for high voltage output.
2Reliability
If discharge circuit is used to discharge energy storage devices with voltage imbalance, then charge capacity variations are suppressed, but the voltage of high charge rate devices may still exceed threshold causing malfunction
Solution Approach 1:
The patent implements preliminary detection of voltage thresholds for each energy storage device before charging operations. When a device's voltage exceeds the predetermined threshold, the system proactively interrupts charging for that specific device in advance, preventing malfunction before it occurs. This preliminary protective action works in conjunction with discharge operations to maintain voltage balance.
Solution Approach 2:
The patent employs continuous voltage detection and monitoring feedback mechanisms that track the voltage status of each energy storage device. Based on real-time feedback from voltage detectors, the control unit dynamically adjusts charging and discharging operations, interrupting charging or activating discharge circuits when threshold violations are detected, thereby maintaining voltage within safe operating ranges.
3Reliability
If charging is interrupted by current interrupting device when voltage exceeds threshold, then malfunction is prevented, but sudden voltage increase occurs due to counter electromotive force from inductance component
Solution Approach 1:
The patent introduces a control unit as an intermediary between the charging system and the energy storage devices. This control unit coordinates discharge operations and charging interruption timing to manage voltage transitions smoothly. By acting as a mediator, the control unit prevents sudden voltage surges that would otherwise occur during direct charging interruption, while still achieving malfunction prevention through controlled voltage management.
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 allows for continued charging while preventing malfunctions by reducing the voltage of the high-voltage device, ensuring stable operation and preventing damage to the management device.
Implementation Method 1
a voltage detection unit that detects voltages of the plurality of energy storage devices
Implementation Method 2
a discharge circuit that discharges the energy storage devices... executes a discharge process of discharging only an energy storage device having a highest voltage
Implementation Method 3
the voltage applied to the energy storage apparatus greatly increases due to the influence of a counter electromotive force due to an inductance component
Data Source
AI summary
An energy storage apparatus includes: a plurality of energy storage devices connected in series; a voltage detection unit that detects voltages of the plurality of energy storage devices; a discharge circuit that discharges the energy storage devices; and a control unit. The energy storage devices include lithium ion cells. The plurality of energy storage devices is chargeable by an external charger for a lead-acid battery, wherein a charge voltage per cell of the external charger for the lead-acid battery is higher than a maximum voltage of the energy storage device, and wherein the control unit discharges only an energy storage device having a highest voltage out of the plurality of energy storage devices when the plurality of energy storage devices is charged by a charger.