Load Circuit Protective Device Dynamic Sampling
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Solution Overview
Problem
Conventional protective devices for load circuits continue to consume significant power after the semiconductor relay is turned off, as they maintain active temperature estimation until the wire reaches ambient temperature.
Innovation Solution
A protective device that adjusts sampling periods based on the relay's status, using a shorter period when the relay is on and a longer period when it's off, and enters a sleep mode when the wire temperature drops below a threshold, reducing power consumption by minimizing unnecessary calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the temperature estimation continues until the wire reaches ambient temperature after the relay is turned off, then the temperature monitoring reliability is maintained, but the power consumption increases significantly
Solution Approach 1:
The patent applies dynamics by making the sampling period adjustable based on the relay state. When the relay is ON, a first sampling period is used for accurate temperature monitoring. When the relay is OFF, a second sampling period (longer than the first) is used, reducing calculation frequency and power consumption while maintaining sufficient monitoring capability until the wire cools to ambient temperature.
Solution Approach 2:
The patent changes the sampling period parameter based on the relay's operational state. By switching between two different sampling periods (first sampling period when relay is ON, second sampling period when relay is OFF), the system optimizes the balance between temperature monitoring accuracy and power consumption, directly addressing the technical contradiction.
2Measurement precision
If a shorter sampling period is used for accurate temperature estimation, then the temperature measurement precision is improved, but the power consumption increases
Solution Approach 1:
The system dynamically adjusts the sampling period based on whether the relay is ON or OFF. During relay operation, a shorter first sampling period ensures accurate temperature measurement precision. During relay off-state, a longer second sampling period reduces calculation frequency and power consumption, since the wire is naturally cooling and rapid temperature changes are less likely.
Solution Approach 2:
The sampling period parameter is changed according to the relay state. The first sampling period provides high measurement precision when needed (relay ON), while the second sampling period reduces power consumption during relay OFF periods when temperature changes are slower, effectively resolving the contradiction between precision and energy use.
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 for accurate temperature estimation while current flows and reduces power consumption when current is not flowing, thereby efficiently managing power usage and enabling quick reactivation of the relay.
Implementation Method 1
a current sensor for detecting current flowing through the wire of the load circuit
Implementation Method 2
measures load current at each predetermined sampling period; estimates wire temperature based on a period of time when the load current flows
Implementation Method 3
estimates wire temperature based on a period of time when the load current flows
Data Source
AI summary
A load circuit protective device calculates increasing temperature of wire of a load circuit with a first predetermined sampling period (dt1) determined by a clock signal for normal operation when a semiconductor relay (Q1) is on to estimate the temperature of the wire. The temperature of the wire is therefore estimated with high accuracy. Moreover, when the semiconductor relay (Q1) is off, the load circuit protective device calculates decreasing temperature of the wire of the load circuit with a second predetermined sampling period (dt2) to estimate the temperature of the wire. The second predetermined sampling period (dt2) is determined by a clock signal for power-saving operation and is longer than the first predetermined sampling period (dt1). Accordingly, the calculation times of the temperature can be reduced, and the power consumption is therefore reduced.