Autonomous Solenoid Driver Circuit for Pull-In and Hold Switching
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Solution Overview
Problem
Existing solenoid drive circuits lack the ability to automatically switch from 'Hold' mode to 'Pull-in' mode in response to power interruptions or faults, leading to inefficient power usage and reliance on software-based solutions that increase complexity.
Innovation Solution
A hardware-based circuit topology using a PWM-based current drive coupled with a comparator-based autonomous mode change circuit, which automatically switches between 'Pull-in' and 'Hold' modes based on solenoid current levels, eliminating the need for additional software overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full rated voltage is applied continuously to energize the solenoid, then the solenoid remains reliably engaged, but power dissipation within the drive circuit and solenoid increases significantly
Solution Approach 1:
The patent applies periodic PWM (pulse-width modulation) voltage to the solenoid coil instead of continuous DC voltage. The controller switches between full rated voltage and zero voltage in periodic pulses, where the duty cycle of the PWM signal controls the average power delivered. This periodic action maintains solenoid engagement through sufficient average magnetic force while dramatically reducing continuous power dissipation, directly resolving the contradiction between reliability and energy loss.
2Loss of energy
If a voltage controlled drive circuit applies full regulated voltage to pull-in the solenoid and then reduced voltage to hold, then power dissipation is reduced, but the system requires complex software control for mode switching
Solution Approach 1:
The patent implements autonomous mode switching where the controller automatically transitions between pull-in and hold modes based on real-time monitoring of solenoid current or voltage thresholds. The system self-regulates by detecting when the solenoid reaches full engagement (through current threshold detection) and autonomously switches from full voltage to reduced voltage without requiring external software commands. This self-service mechanism eliminates software overhead while maintaining energy efficiency, resolving the contradiction between reduced power dissipation and control complexity.
3Adaptability or versatility
If software-based mode switching is used to manage solenoid operation, then flexibility is maintained, but system complexity increases and additional software overhead is required
Solution Approach 1:
The patent replaces software-based control logic with hardware-based autonomous control circuitry that monitors solenoid parameters and automatically adjusts drive voltage. The controller uses hardware comparators or threshold detectors to monitor current levels and automatically switches between pull-in and hold modes based on predefined electrical thresholds. This hardware substitution maintains the adaptability of mode switching while eliminating the need for software overhead, directly resolving the contradiction between flexibility and system complexity.
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 solution enables efficient power conservation by automatically switching to 'Hold' mode during normal operation and back to 'Pull-in' mode upon power restoration or fault recovery, simplifying system configuration and reducing power dissipation.
Implementation Method 1
A PWM-based current drive circuit is coupled to a comparator-based autonomous mode change circuit
Implementation Method 2
the command to control an operation of the solenoid is determined by the comparator
Data Source
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AI summary
Provided are embodiments for operating an autonomous mode change circuit for solenoid drivers. The embodiments include initiating an operation of a solenoid (302), and receiving a command to control the operation of the solenoid. The embodiments also include controlling, by a drive circuit (308), a switch coupled to the solenoid based at least in part on the command, and detecting at least one of a current or voltage of the solenoid, and subsequently controlling the operation of the solenoid based at least in part on the detection.