Battery Protection Circuit with Dual Switch Drivers
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Solution Overview
Problem
Conventional battery protecting circuits face challenges in maintaining stable charging currents when the battery voltage falls to zero volts due to overdischarge, leading to intermittent charging and potential battery degradation.
Innovation Solution
A battery protecting circuit that controls the ON/OFF of switching circuits using driving voltages generated by boosting the voltage in the power feeding path, ensuring steady charging with a constant current even when the battery voltage is low, by employing a first switch driver for the initial power feeding path and a second switch driver for a separate power feeding path, with a controller managing the switching operations based on the battery voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a boosting circuit is used to generate driving voltage for NMOS transistors, then the transistor can be turned ON effectively, but when battery voltage falls to zero volts, the boosting operation cannot be performed and charging becomes intermittent
Solution Approach 1:
The power feeding path is divided into two separate paths: one for boosting operation and another for direct voltage feeding. This segmentation allows the circuit to handle low-voltage conditions by switching to the direct feeding path when boosting cannot be performed, thereby maintaining charging stability without requiring complex voltage conversion mechanisms.
Solution Approach 2:
A second switching circuit is introduced as an intermediary element to provide an alternative current path when the first switching circuit cannot operate due to insufficient voltage. This intermediary circuit ensures continuous charging by bypassing the boosting requirement when battery voltage falls to zero volts.
2Ease of operation
If a single switching circuit is used in the power feeding path, then the circuit structure is simple, but when voltage is insufficient for boosting, the transistor cannot be turned ON and charging becomes intermittent
Solution Approach 1:
The circuit dynamically switches between two operating modes: boosting mode when voltage is sufficient, and direct voltage feeding mode when voltage is insufficient. The controller adjusts the operation of switching circuits based on real-time voltage conditions, ensuring continuous charging operation across different voltage states without requiring manual intervention.
3Power
If boosting operation is performed at low voltage, then driving voltage can be generated, but the boosting operation itself fails when battery voltage reaches zero volts
Solution Approach 1:
The circuit is designed to detect voltage levels in advance and switch to the direct voltage feeding path before the boosting operation fails completely. This preliminary action prevents the intermittent charging problem by proactively transitioning to an alternative operating mode when voltage falls below the threshold required for boosting.
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 solution enables steady and constant charging currents to the battery, preventing degradation and ensuring reliable operation even when the battery voltage drops to zero volts, while reducing the risk of misjudging the battery state by electronic equipment.
Implementation Method 1
a first switch driver that generates a first driving voltage by boosting the voltage generated in said first power feeding path
Implementation Method 2
a second switch driver that generates a second driving voltage lower than the voltage generated in a second power feeding path
Data Source
AI summary
This invention provides a battery protecting circuit where even if the battery voltage falls nearly to zero volts due to overdischarge or the like while an NMOS transistor set in the power feeding path on the side of the positive electrode of the battery is turned ON/OFF, it is still possible to charge the battery by a constant charging current in a stable way. When the voltage of battery B1 has not reached the voltage needed for generating the driving voltage of NMOS transistors Q1, Q2 in drives 111, 112, the boosting operation of drives 111, 112 is stopped, and PMOS transistor Q3 inserted in a power feeding path different from that of said transistors is turned ON by driver 113. In driver 113, by clamping voltage VDD generated in the power feeding path of PMOS transistor Q3 to a voltage lower than it, driving voltage ZVO of PMOS transistor Q3 is generated without performing a boosting operation.