Battery Pack Voltage Detection Circuit Balancing
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Solution Overview
Problem
Battery packs with multiple voltage detection circuits experience unbalanced discharge currents, leading to uneven battery degradation, as the current drawn by voltage detection circuits is not balanced across all batteries, and existing solutions fail to maintain balanced discharge when the output state of voltage detection circuits changes.
Innovation Solution
The battery pack incorporates output resistors connected to ground and discharge circuits with balance resistors and switching devices, ensuring balanced discharge by activating the switching device to discharge unbalanced batteries when the voltage detection circuit output is HIGH and deactivating it when the output is LOW, preventing any discharge when the output is LOW.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple voltage detection circuits are used to detect battery voltage, then voltage detection capability is improved, but current balance deteriorates due to unbalanced discharge currents
Solution Approach 1:
A current balance circuit is introduced as an intermediary component between the voltage detection circuits and the batteries. This circuit includes switching elements that are controlled based on detection signals to adjust and balance the discharge currents flowing from each battery, thereby resolving the current imbalance caused by multiple voltage detection circuits
Solution Approach 2:
The system uses detection signals from the voltage detection circuits as feedback to control the switching elements in the current balance circuit. Based on the detected voltage states, the switching elements adjust the discharge paths to ensure balanced current distribution across all batteries
2Reliability
If balance resistors are connected in parallel with batteries to balance currents, then current balance is improved, but adaptability deteriorates when voltage detection circuit output state changes
Solution Approach 1:
The current balance circuit uses controllable switching elements instead of fixed resistors. These switching elements can dynamically change their state (on/off) based on the output state of the voltage detection circuits, allowing the circuit to adapt its current balancing behavior to different operating conditions
Solution Approach 2:
The switching elements are pre-configured in the circuit but remain inactive until needed. When the voltage detection circuit outputs indicate an imbalance condition, the switching elements are activated in advance to correct the current balance before significant degradation occurs
3Ease of operation
If voltage detection circuit output controls discharge switching, then discharge control is improved, but current balance deteriorates due to HIGH/LOW state variations
Solution Approach 1:
The current balance circuit is segmented into multiple independent branches, each associated with a specific voltage detection circuit. Each branch contains switching elements that can be independently controlled based on the output state of its corresponding detection circuit, allowing fine-grained control of current balance
Data Source
AI summary
A battery pack that detects the voltage of a plurality of batteries (1) connected in series with a plurality of voltage detection circuits (2). When a voltage detection circuit output is HIGH, batteries (1) discharge through an output resistor (6). In addition, discharge circuits (7), which are series connections of balance resistors (8) and switching devices (9), are connected in parallel with batteries (1) left “un-discharged” by the output resistors (6). When a voltage detection circuit output is HIGH, some batteries (1) are discharged by the output resistor (6) and the “un-discharged” batteries (1) are discharged by the discharge circuit (7). When a voltage detection circuit output is LOW, no batteries (1) are discharged by the output resistor (6) and the “un-discharged” batteries (1) are also left un-discharged by the discharge circuit (7) to balance the discharge currents of all the batteries (1).