Solid State Relay Power Harvesting With Capacitor Voltage Feedback
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Solution Overview
Problem
Existing relay circuits that derive power from a load face challenges in determining the optimal time to recharge a supply capacitor, as this time depends on various factors such as load inductance, capacitor size, current, and resistance, leading to incomplete charging or unnecessary disconnection.
Innovation Solution
A solid state relay circuit that includes a control circuit to automatically turn the relay on and off based on capacitor voltage thresholds, ensuring sufficient charge is maintained by toggling the relay between ON and OFF states when the voltage falls below a low threshold and rises above a high threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the relay is turned off for a fixed time to recharge the capacitor, then the capacitor can be recharged, but the load may be disconnected for more time than necessary
Solution Approach 1:
The patent implements a feedback mechanism where the controller monitors the capacitor voltage in real-time and dynamically adjusts the relay switching timing based on the actual charging progress. The controller detects when the capacitor voltage reaches a threshold level and immediately turns the relay back on, rather than using a predetermined fixed time interval. This feedback-based control ensures the load is disconnected only for the minimum necessary time while still achieving complete capacitor recharge.
2Loss of time
If the relay is turned off for a fixed time to recharge the capacitor, then the capacitor can be recharged, but the charging time may not be sufficient
Solution Approach 1:
The controller continuously monitors the capacitor voltage during the off-state and uses this feedback information to determine the optimal moment to resume operation. Rather than relying on a fixed time estimate, the system adapts the charging duration to the actual electrical conditions, ensuring sufficient charge accumulation before reconnecting the load.
Solution Approach 2:
The patent transitions from a static, fixed-time switching approach to a dynamic, adaptive switching strategy. The relay off-time is no longer a constant value but varies based on real-time measurements of capacitor voltage, load conditions, and charging rate. This dynamic adjustment allows the system to optimize charging time for each operational cycle based on actual system state.
3Duration of action of stationary object
If the relay is kept on continuously, then the load operates without interruption, but the capacitor voltage may fall below the threshold required for proper operation
Solution Approach 1:
The controller monitors capacitor voltage levels and uses this feedback to determine when switching to the off-state is necessary. By continuously tracking the voltage and comparing it against threshold values, the system can proactively initiate the recharge cycle before the voltage drops to levels that would compromise reliable operation, thus maintaining both continuous operation and operational reliability.
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 optimizes the performance by maintaining the relay in the ON state for the necessary time, ensuring continuous operation while minimizing the duration of the OFF state, thus efficiently managing power harvesting and reducing unnecessary disconnection.
Implementation Method 1
a solid state relay switch (112) having a first end and a second end
Implementation Method 2
a charging capacitor (C0), arranged to store power when the solid state relay switch (112) is in an OFF state
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A relay circuit may include a solid state relay switch, coupled to an external voltage line and to an charging capacitor; and a solid state relay control circuit, coupled between the charging capacitor and the solid state relay switch. The solid state relay control circuit may be arranged to: turn the solid state relay switch to an OFF state when a capacitor voltage of the charging capacitor falls below a low threshold value; and change the solid state relay switch from the OFF state to an ON state when the capacitor voltage increases above a high threshold value.