Battery Module Parallel Circuit With Variable Resistance Equalization
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Solution Overview
Problem
In power supply devices with two battery modules connected in series, a voltage difference can occur due to differing states of charge, leading to circulation currents when connected in parallel, which can generate arcs or excessive currents at relay contacts.
Innovation Solution
A power supply device with a connection circuit that includes a variable resistor interposed between the two battery modules in parallel, and a control device that adjusts the resistance value to reduce circulation currents and eliminate voltage differences quickly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed resistor is interposed between battery modules to suppress arc generation and circulation current, then relay safety is improved, but the time required to eliminate voltage difference between battery modules increases significantly
Solution Approach 1:
The patent applies the dynamics principle by replacing the fixed resistor with a variable resistor whose resistance value can be dynamically adjusted during the parallel connection process. The control device changes the resistance value over time, starting with a higher resistance to limit circulation current and arc generation, then progressively reducing it to accelerate voltage difference elimination, thus resolving the contradiction between relay safety and time efficiency.
Solution Approach 2:
The patent applies parameter changes by modifying the resistance value parameter of the resistor from a constant value to a time-varying value. The control device adjusts the resistance parameter based on the voltage difference between battery modules, initially setting it to a higher value to suppress circulation current and arcs, then gradually reducing it to speed up voltage equalization, thereby resolving the contradiction between reliability and time loss.
2Ease of operation
If battery modules with voltage difference are connected in parallel without resistance suppression, then parallel connection frequency and device convenience are improved, but arc generation and excessive circulation current occur at relay contacts
Solution Approach 1:
The patent applies the intermediary principle by introducing a variable resistor as a mediator between the battery modules during parallel connection. This intermediary component temporarily limits the circulation current and suppresses arc generation at relay contacts, allowing safe parallel connection even when voltage differences exist between modules, thus resolving the contradiction between ease of operation and harmful factors.
Solution Approach 2:
The patent applies preliminary anti-action by proactively introducing resistance suppression before the harmful effects of circulation current and arcs can occur. The control device activates the variable resistor prior to full parallel connection, preventing arc generation and excessive current flow, then gradually reduces the resistance as the voltage difference diminishes, allowing frequent safe parallel connections without relay damage.
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 arc generation and excessive circulation currents, allowing for more frequent parallel connection of battery modules without impairing the function and convenience of the power supply device.
Implementation Method 1
a variable resistor provided in the connection circuit and interposed between the first battery module and the second battery module in the parallel circuit
Implementation Method 2
The control device is configured to execute a current adjustment process for reducing the resistance value of the variable resistor continuously or stepwise
Data Source
AI summary
The power supply device includes: a first battery module and a second battery module that can be charged by an external power source; a series circuit in which the first battery module and the second battery module are connected in series; a connection circuit that selectively forms a parallel circuit in which the first battery module and the second battery module are connected in parallel; a variable resistor provided in the connection circuit and interposed between the first battery module and the second battery module in the parallel circuit; and a control device that controls the resistance values of the opening and closing of the plurality of relays and the variable resistor. The control device is configured to be capable of performing a current adjustment process of continuously or stepwise lowering the resistance value of the variable resistor after the parallel circuit is formed by controlling the plurality of relays.