Programmable Solid-State Relay Digital Timing Control
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Solution Overview
Problem
Existing time delay relays in the railway industry, particularly those using resistor-capacitor (RC) circuits, face challenges with inaccurate and unpredictable timing due to exponential current discharge, temperature and aging effects, and mechanical issues in electromechanical relays, leading to reliability concerns and unsafe switch states.
Innovation Solution
A programmable solid-state relay with a base module, configuration module, control voltage module, controller module, and switch module, utilizing microcontrollers, energy storage devices, and optically isolated mosfets, which allows for precise time delay control and fault detection, ensuring reliable operation even during temporary power interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RC circuit time delay is used, then the relay can provide time delay function, but the timing accuracy deteriorates due to exponential current discharge and temperature effects
Solution Approach 1:
The patent replaces the RC circuit time delay mechanism with a microcontroller-based digital timing system. The microcontroller uses a crystal oscillator to generate precise clock pulses and counts these pulses to achieve accurate time delays, eliminating the exponential discharge characteristics and temperature sensitivity of RC circuits.
Solution Approach 2:
The patent changes the timing mechanism from analog RC time constants to digital pulse counting. By using a stable crystal oscillator frequency and counting integer numbers of clock cycles, the system achieves predictable and programmable time delays that are not affected by component tolerances or environmental conditions.
2Reliability
If electromechanical relay is used, then the relay can provide switching function, but the reliability deteriorates due to mechanical wear and contact resistance
Solution Approach 1:
The patent replaces electromechanical relay contacts with solid-state MOSFET switching devices. The MOSFETs are controlled by the microcontroller to open or close circuits without any mechanical moving parts, eliminating contact wear, pitting, and resistance issues while maintaining the switching function.
3Adaptability or versatility
If RC circuit with potentiometer is used, then the time delay can be adjusted, but the complexity of setting and calibration increases
Solution Approach 1:
The patent implements self-calibration functionality where the microcontroller automatically measures the actual time delay achieved and adjusts the timing parameters to compensate for any variations. This eliminates the need for manual trial-and-error adjustment of potentiometers while maintaining programmable time delay settings.
Solution Approach 2:
The patent transitions from manual potentiometer adjustment to digital programming of time delay values. The microcontroller reads preset time values from memory and automatically configures the timing circuit, allowing easy reconfiguration through software without physical adjustment of components.
4Adaptability or versatility
If fixed value capacitor and variable resistor are used, then the time delay can be selected, but the prediction accuracy of time delay deteriorates
Solution Approach 1:
The patent changes from analog component-based timing to digital pulse counting with a stable crystal oscillator. The time delay is calculated as an integer number of clock cycles, providing exact and predictable timing that can be precisely programmed without dependence on component tolerances or environmental variations.
Data Source
AI summary
A programmable solid-state relay includes a base module; a configuration module; a control voltage module having an energy storage device; a controller module having at least two microcontrollers, each having an internal EEPROM memory and at least one digital timer; and at least one switch module including at least one switching circuit having first and second switching contacts. The control voltage module is adapted to receive an applied control voltage and to permit pre-selection of an activation voltage level and a de-activation voltage level.