Latching Relay Pulse Control for Low-Loss Overcurrent Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-power switching applications face challenges with solid-state switches due to high power dissipation, and electromechanical relays suffer from reduced lifetime, bouncing, arcing, overheating, and slow switching speeds, making them inefficient for high-efficiency switching of large AC currents.
Innovation Solution
A pulse-controlled bistable switch, specifically a latching relay, is synchronized with zero crossings of AC power to optimize switching times, using shaped pulses to reduce bounce and overheating, and providing overcurrent protection by sensing current conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If solid-state switches are used for high-power switching, then switching speed is improved, but power dissipation increases
Solution Approach 1:
The patent introduces a current transformer as an intermediary device to sense the current through the load without being part of the high-current path. This allows the control circuit to monitor current conditions and implement protection without the switch itself needing to handle the full power dissipation burden, enabling faster switching with reduced energy loss.
Solution Approach 2:
The patent replaces traditional electromechanical relay switches with solid-state switching components controlled by a microcontroller. This substitution enables much faster switching speeds while the current transformer provides non-contact current sensing, eliminating the mechanical wear and high power dissipation associated with traditional high-power relays.
2Loss of energy
If electromechanical relays are used for high-power switching, then power dissipation is reduced, but lifetime is shortened
Solution Approach 1:
The current transformer acts as an intermediary that enables the control system to monitor and protect the relay without direct contact with the high-current path. This allows the relay to operate with minimal stress while the system provides overcurrent protection, extending its operational lifetime while maintaining low power dissipation characteristics.
Solution Approach 2:
The patent implements a feedback mechanism where the current transformer continuously monitors the current through the load and provides this information to the microcontroller. When overcurrent conditions are detected, the system can take protective action, preventing damage to the relay and extending its service life while maintaining efficient power dissipation.
3Loss of energy
If relays are used for high-current switching, then power loss is reduced, but switching speed becomes slow
Solution Approach 1:
The patent replaces the mechanical switching mechanism with solid-state switching components that can operate at much higher speeds. The current transformer enables precise control and protection of the switching operation, allowing the system to achieve both low power loss and fast switching speeds by combining solid-state speed with intelligent control.
Solution Approach 2:
The system implements self-service through automatic overcurrent protection and monitoring. The current transformer and microcontroller work together to automatically detect and respond to abnormal conditions, protecting the switching components and enabling them to operate at optimal speeds without mechanical wear limitations.
4Temperature
If latching relays are used with pulse control, then coil overheating is reduced, but switching precision may be affected
Solution Approach 1:
The patent uses the current transformer to provide real-time feedback on current conditions to the microcontroller. This feedback mechanism allows the system to precisely control the pulse width and timing of the latching relay activation, ensuring accurate switching while maintaining reduced coil temperature through optimized pulse duration.
Solution Approach 2:
The system dynamically adjusts the pulse parameters (width, amplitude, timing) based on the specific switching requirements and current conditions. The microcontroller can modify these parameters in real-time to achieve precise switching control while keeping the coil temperature within acceptable limits, resolving the trade-off between temperature reduction and switching precision.
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 extends the reliability and lifetime of relays while enabling efficient high-current switching with reduced power loss and improved switching speed, protecting both the switch and load from spikes and overcurrent conditions.
Implementation Method 1
A current transformer may be coupled to the power line and configured to sense a current through the load
Data Source
AI summary
A method for switching power supplied by a powerline to a load includes coupling a current sense device and a pulse-controllable bistable switch between the powerline and the load. A sense signal, representative of the current through the load, is applied to a condition detector. The condition detector compares the sense signal value with a threshold to detect a first overcurrent condition. In response to detecting the first overcurrent condition, a second shaped pulse is applied to the pulse-controllable bistable switch to deassert it. The second shaped pulse has an amplitude of at least 110% of a maximum continuous energization voltage and a duration shorter than a predetermined maximum duration. The second shaped pulse may begin at least fifty milliseconds (50 ms) after a prior second shaped pulse ended.