Backup Power Circuit With Leakage Suppression During Battery Charging
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Solution Overview
Problem
Conventional backup power supply devices experience current leakage from storage batteries during charging due to the battery voltage exceeding the input voltage, particularly in nickel-metal hydride batteries, which requires full charging beyond the nominal voltage.
Innovation Solution
A backup power supply device with a discharge suppression section using diodes or FETs in series to suppress current leakage by dropping the excess voltage difference between the battery and input voltage during charging, utilizing a control unit to manage the charge and discharge switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the storage battery is charged until the battery voltage reaches the full charge voltage value higher than the nominal voltage, then the storage battery can be fully charged, but current leakage occurs from the storage battery when the battery voltage exceeds the input voltage
Solution Approach 1:
A discharge suppression section is introduced as an intermediary component between the storage battery and the external power supply apparatus. This section includes a discharge suppression switch and optional current limiting resistance that activates when the battery voltage exceeds the input voltage, suppressing the reverse current leakage while allowing normal charging operation to complete
Solution Approach 2:
The system dynamically changes the resistance parameter in the discharge suppression section based on the voltage difference between the storage battery and external power supply. When the battery voltage exceeds the input voltage by more than a predetermined threshold, a current limiting resistance is connected to suppress reverse current; when the voltage difference is within the threshold, the resistance is disconnected to minimize power loss during normal charging
2Object-generated harmful factors
If a discharge suppression section is added to prevent current leakage, then current leakage is suppressed, but the number of components increases
Solution Approach 1:
The discharge suppression section is designed to serve multiple functions: it suppresses reverse current leakage during overvoltage conditions, limits current to protect the storage battery, and can function as a voltage regulation mechanism. The control section integrates the detection and control logic for both charging and discharge suppression operations, reducing the need for separate dedicated components
Solution Approach 2:
The patent employs simple, low-cost components for the discharge suppression section, including basic switches (such as MOSFETs or diodes) and current limiting resistances. These components are designed to be simple and inexpensive, accepting that they may need to be replaced or are single-use protective elements rather than long-lasting high-cost components
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 prevents current leakage from storage batteries during charging with a minimal component count, ensuring low manufacturing costs and efficient operation.
Implementation Method 1
a discharge switch consisting of a field effect transistor and causing the storage battery to discharge toward the load apparatus
Data Source
AI summary
A backup power supply device includes: a storage battery charged with power from an external power supply; charge switches for charging the storage batter; discharge switches that are made from a field-effect transistor and that discharge the storage battery to a load device; a control unit for controlling the charge switches and the discharge switches; and a discharge suppression section connected in series to the discharge switches. The discharge suppression section suppresses leakage of current from the storage battery only when the control unit charges the storage battery, and the battery voltage exceeds an input voltage and the difference voltage between the battery voltage and the input voltage is less than a prescribed value.