Power Storage Charging Control for Safe Parallel Voltage Equalization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power supply devices face issues with large currents flowing from a second power storage unit to a first power storage unit when connected in parallel, potentially causing defects in the connecting wires.
Innovation Solution
A power supply device with a control device that executes one-side charging control, ensuring only the first power storage unit is charged until its voltage equals or exceeds the second unit's voltage, using a series of relays and capacitors to manage the connection and suppress the flow of large currents through diodes in the inverter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the first power storage unit and the second power storage unit are connected in parallel without voltage comparison, then the charging process is simple and fast, but a large current flows from the second power storage unit to the first power storage unit causing wire defects
Solution Approach 1:
The control device performs voltage comparison between the first and second power storage units before connecting them in parallel. If the voltage difference exceeds a predetermined threshold, the control device charges the first power storage unit through the charging power line until the voltage difference is within the threshold, preventing large current flow when parallel connection occurs.
Solution Approach 2:
The control device continuously monitors the voltage of both power storage units and adjusts the charging process based on the voltage difference feedback. When the voltage difference exceeds the threshold, the control device activates the charging process; when the voltage difference is within the threshold, the control device stops charging, ensuring safe parallel connection conditions.
2Reliability
If voltage comparison and one-side charging control are implemented before parallel connection, then large currents are suppressed and wire defects are prevented, but the charging process becomes more complex and time-consuming
Solution Approach 1:
The control device automatically performs voltage comparison and determines whether one-side charging is needed without requiring external intervention or complex control algorithms. The system self-regulates the charging process based on the voltage difference between the two power storage units, simplifying the overall control complexity while ensuring reliability.
3Object-affected harmful factors
If the voltage of the first power storage unit is less than the second before parallel connection, then a large current flows from the second to the first power storage unit through the inverter diodes, but implementing one-side charging control prevents this current flow by equalizing voltages first
Solution Approach 1:
The charging power line acts as an intermediary path to equalize the voltage of the first power storage unit with the second before parallel connection. By using this intermediate charging process, the system prevents direct large current flow through the inverter diodes, which would occur if parallel connection happened without voltage equalization.
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 effectively suppresses large currents from flowing from the second power storage unit to the first, preventing defects and ensuring safe parallel connection by managing voltage differences and applying bias voltage in the forward direction.
Implementation Method 1
a control device that executes one-side charging control when a voltage of the first power storage unit is less than a voltage of the second power storage unit before the first power storage unit and the second power storage unit are connected in parallel
Implementation Method 2
a power storage device that includes a first power storage unit and a second power storage unit
Implementation Method 3
system main relay that includes a positive-side relay attached to a positive-side line of a power line that connects between the power storage device and the inverter, a negative-side relay attached to a negative-side line of the power line
Implementation Method 4
an inverter that includes a plurality of switching elements and diodes connected in parallel in an opposite direction to the respective switching elements
Implementation Method 5
a second capacitor attached between a portion of the neutral point line between the first neutral point relay and the second neutral point relay and a portion of the negative-side line of the power line on the inverter side
Data Source
AI summary
The power supply device performs one-side charge control for controlling the system main relay, the charging relay, the series connection relay, the parallel connection relay, and the first and second neutral point relays so that only the first power storage unit is charged using the external DC power until the voltage of the first power storage unit becomes equal to or higher than the voltage of the second power storage unit before the first and second neutral point relays are turned on and the power storage device is charged using the external DC power.