Power stealing in relay circuits
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Solution Overview
Problem
Thermostats and other electronic devices in power-control circuits face challenges in maintaining power supply when the relay is in an activated state for extended periods, leading to battery drain and system failure.
Innovation Solution
The electronic device employs voltage-drop circuitry connected in the power-control circuit to harvest energy while the relay is in an activated state, using multiple circuit paths and switches to manage current flow and maintain relay activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a battery is used as power supply for thermostat electronics, then the thermostat can operate independently without external power wiring, but the battery requires frequent checking and replacement
Solution Approach 1:
The thermostat system performs self-service by harvesting power from the power-control circuit it controls. The voltage-drop circuitry extracts energy from the circuit during normal operation, allowing the thermostat to recharge its battery automatically without external intervention or manual battery replacement
Solution Approach 2:
The system changes the electrical parameters of the power-control circuit by introducing voltage-drop circuitry that modifies the circuit behavior. This allows power extraction at different stages: when the relay is activated, the circuit provides power through the voltage drop across the relay coil, and when deactivated, power is stolen through the voltage-drop circuitry
2Use of energy by moving object
If power is stolen from the power-control circuit, then the electronic device can recharge its battery, but the relay may deactivate due to insufficient current
Solution Approach 1:
The system dynamically switches between different power extraction modes based on relay state. When the relay is activated, power is stolen through the voltage-drop circuitry in a way that maintains sufficient current for relay operation. When the relay is deactivated, the system can extract more power without concern for maintaining relay activation
Solution Approach 2:
The system monitors the state of the relay and adjusts its power extraction accordingly. The controller detects whether the relay is activated or deactivated and modulates the power-stealing operation to ensure relay functionality is maintained when needed while maximizing battery recharging when the relay is not active
3Adaptability or versatility
If multiple circuit paths with switches are used to manage current flow, then the electronic device can control power harvesting while maintaining relay activation, but the device complexity increases
Solution Approach 1:
The power-control circuit is segmented into multiple independent circuit paths, each controlled by its own switch. This allows the system to selectively activate different power extraction mechanisms based on operational requirements, providing flexibility in power management while isolating control functions
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 approach allows the electronic device to recharge its battery and power components while maintaining the relay in an activated state, reducing the need for frequent battery replacements and ensuring continuous system operation.
Implementation Method 1
voltage-drop circuitry connected in the power-control circuit to harvest energy while the relay is in an activated state
Data Source
AI summary
Techniques for an electronic device to perform power-stealing techniques to harvest energy from a power-control circuit to power components of the electronic device. In some examples, the electronic device may be connected in the power-control circuit between a power supply and a relay that is selectively configured to activate a power load. According to the techniques described herein, the electronic device may include voltage-drop circuitry that is connected in the power-control circuit such that a voltage drop is produced across electrical components of the electronic device while the relay is in the activated, or triggered, state. In this way, the electronic device may perform power-stealing from the power-control circuit while the relay is maintained in the activated state.