Relay Actuation Delay Circuit for Zero-Crossing Inrush Current Reduction
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Solution Overview
Problem
Existing solutions for delaying the actuation of relays, such as electromechanical relays, lack efficient methods for detecting peak or valley values in rectified voltage ripple waveforms, which are necessary for reducing inrush current and extending relay lifespan.
Innovation Solution
A system comprising a relay, an actuation circuit, and an actuation delay circuit that detects peak or valley values in rectified voltage ripple waveforms to delay actuation, ensuring current flow coincides with zero-crossing times of the input voltage or current waveform, thereby reducing inrush current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zero-cross detection circuits with numerous hardware components and software algorithms are used to detect zero crossing, then relay actuation can be delayed to reduce inrush current, but device complexity increases
Solution Approach 1:
The patent extracts only the essential function needed for zero-cross detection by removing unnecessary hardware components and software algorithms. It uses a simplified circuit that detects the peak or valley of rectified voltage ripple waveform and calculates the corresponding zero-crossing time, keeping only the minimal required elements for the detection function.
Solution Approach 2:
The patent creates a simplified model or representation of the zero-crossing detection function by using peak/valley detection of rectified voltage ripple as a proxy. Instead of directly detecting the complex zero-crossing point, it detects an equivalent characteristic (peak/valley of rectified waveform) and derives the zero-crossing information from that, reducing hardware requirements.
2Ease of operation
If traditional zero-cross detection methods are used, then relay actuation timing can be controlled, but the system requires numerous hardware components and processing devices
Solution Approach 1:
The patent replaces complex electronic processing systems with a simpler detection mechanism. Instead of using processing devices to execute software algorithms for zero-cross detection, it uses a hardware-based peak/valley detection circuit that naturally identifies the relevant waveform characteristics and generates the timing signal directly.
Solution Approach 2:
The detection circuit serves itself by using the rectified voltage ripple waveform inherently present in the power system. The circuit detects the peak or valley of this existing waveform and automatically calculates the corresponding zero-crossing time without requiring external processing devices or complex control logic.
3Object-generated harmful factors
If relay actuation is delayed to coincide with zero-crossing, then inrush current is reduced, but precise timing control is required
Solution Approach 1:
The patent performs preliminary detection of the peak or valley of the rectified voltage ripple waveform and pre-calculates the corresponding zero-crossing time. This advance detection and calculation ensure that when the relay actuation signal is generated, the timing is already precisely determined, eliminating the need for real-time high-precision timing control during the actual actuation moment.
Solution Approach 2:
The patent introduces an intermediary calculation step that converts the easily detectable peak/valley timing of the rectified waveform into the corresponding zero-crossing time. This intermediary process acts as a bridge between simple detection and precise timing control, translating a readily observable waveform characteristic into the precise timing information needed for relay actuation.
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
The solution effectively delays relay actuation to align with zero-crossing times, minimizing inrush current and extending relay lifespan by using a resistor-capacitor network configured based on peak or valley detection, reducing hardware complexity and improving operational efficiency.
Implementation Method 1
The actuation delay circuit is configured based on the peak or valley of the rectified voltage ripple waveform
Implementation Method 2
using a resistor-capacitor network configured based on peak or valley detection
Implementation Method 3
The relay can include an actuation coil
Data Source
AI summary
A system includes a relay, an actuation circuit, and an actuation delay circuit. The relay is coupled to a source of an input voltage or current waveform. The relay includes an actuation coil. The actuation circuit detects a peak or valley of a rectified voltage ripple waveform. The rectified voltage ripple waveform is generated from the input voltage or current waveform. The actuation circuit also causes an actuation voltage to be provided to the actuation coil. The actuation delay circuit delays the actuation circuit from providing the actuation voltage. The actuation delay circuit is configured based on the peak or valley of the rectified voltage ripple waveform. The actuation delay generated by the actuation delay circuit causes the relay to begin allowing current to flow to a load device at a time coincident with a zero-crossing time value of the input voltage or current waveform.