Smart Meter Current Limiting Circuit for Battery Protection
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Solution Overview
Problem
Battery-operated smart utility meters face challenges in energy conservation due to self-discharge and high current peaks, which reduce battery life and increase costs, especially when using capacitors to manage energy delivery for radio communication.
Innovation Solution
A utility meter with a power supply circuit that includes a capacitor and a current limiting circuit controlled by a controller unit, which dynamically switches between normal and boost modes based on analyzed radio signal parameters to optimize energy delivery and protect the battery from high current peaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitor is used to decouple the battery from high current peaks, then the battery is protected from current peaks, but the capacitor size must be increased to handle extended high-power periods, which increases cost
Solution Approach 1:
The patent applies a dynamic current limiting circuit that can switch between different current limiting values based on operational conditions. The controller adjusts the current limiting value to be higher during extended high-power periods (when capacitor would need to be large) and lower during normal operation, thereby protecting the battery while allowing the use of a smaller, more cost-effective capacitor
Solution Approach 2:
The patent changes the electrical parameters of the power supply circuit by dynamically adjusting the current limiting value. This parameter change allows the system to adapt to different power demand conditions, enabling extended high-power operation without requiring an oversized capacitor, thus reducing component cost while maintaining battery protection
2Reliability
If a serial resistor is used to protect the battery from high current peaks, then the battery is protected, but the power delivery capability is limited
Solution Approach 1:
The patent replaces the static serial resistor with a dynamic current limiting circuit controlled by a controller unit. This circuit can adjust the current limiting value in real-time, allowing high current delivery when needed (by increasing the limiting value) while still providing protection during normal operation (by maintaining a lower limiting value), thus resolving the trade-off between protection and power delivery
Solution Approach 2:
The patent introduces a controller unit as an intermediary between the battery and the power consumption unit. This intermediary dynamically regulates the charging current based on the state of the capacitor and power demands, replacing the passive serial resistor with an active control system that can optimize both battery protection and power delivery capability
3Duration of action of moving object
If the capacitor size is increased to deliver larger amounts of energy during high demand, then extended high-power periods are supported, but the cost of the smart utility meter increases significantly
Solution Approach 1:
The patent uses a dynamic current limiting circuit that can increase the current limiting value during extended high-power periods, allowing the existing capacitor to be charged and discharged more efficiently. This dynamic adjustment enables the system to support longer high-power operations without requiring a larger capacitor, thereby avoiding the significant cost increase associated with Hybrid Layer Capacitors
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 extends battery life by minimizing self-discharge and reducing capacitor size, while allowing for increased power consumption during high-demand periods, thus enhancing energy efficiency and reducing costs.
Implementation Method 1
a capacitor arranged to be charged by the battery and to supply energy to the power supply circuit
Data Source
Figure 1
AI summary
A utility meter for measuring an amount of a utility delivered to a consumer and for transmitting consumption related data to a meter reading system. The utility meter includes a radio circuit powered by a power supply circuit. The utility meter is battery operated and energy is supplied from the battery to the power supply circuit. The utility meter further includes a controller unit arranged to analyse radio signals received by the radio circuit. To decouple current peaks from the battery a capacitor is charged by the battery through a current limiting circuit. The current limiting circuit is controlled by the controller unit to have a normal mode and a boost mode where the charging current is limited more in normal mode than in boost mode. The controller unit is configured to analyse a radio signal received by the radio receiver to determine a parameter of the received radio signal and to control the current limiting circuit to switch to the boost mode according to the determined parameter.