Solenoid Control Device Short-Circuit Detection via Current Variation
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Solution Overview
Problem
Conventional solenoid control devices fail to accurately detect short-circuits between terminals, leading to hunting phenomena and potential damage due to overcurrent fluctuations.
Innovation Solution
A solenoid control device with an overcurrent detection circuit and a microcomputer that sets a fixed duty ratio and monitors the overcurrent detection signal to prevent damage and detect short-circuits, while also using a battery voltage-dependent duty ratio adjustment to ensure accurate detection and elimination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional overcurrent detection means are used that detect abnormality based on steady state current, then overcurrent can be detected, but short-circuit between terminals accompanied by hunting phenomenon cannot be appropriately detected
Solution Approach 1:
The patent transitions from static overcurrent detection to dynamic detection by monitoring current variation over time. The control unit calculates the absolute value of current variation |Δi| and compares it against a threshold to detect short-circuits during hunting phenomena, making the detection system adaptive to dynamic operating conditions.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the drive current, calculating its variation, and using this information to determine short-circuit occurrence. The system feeds back the current variation state to the control unit, which then adjusts its determination logic based on whether |Δi| exceeds the threshold, enabling accurate detection even during hunting.
2Ease of operation
If PWM switching element is driven to control solenoid current, then feedback control can be executed, but overcurrent is generated when short-circuit occurs between terminals
Solution Approach 1:
The patent applies preliminary protection by detecting short-circuit conditions before they cause severe damage. By monitoring current variation |Δi| and comparing it to a threshold, the system identifies short-circuits early in the hunting phenomenon, allowing protective actions to be taken before excessive current damages the solenoid or control elements.
Solution Approach 2:
The patent introduces current variation |Δi| as an intermediary parameter for detection. Instead of directly responding to the harmful overcurrent, the system uses the intermediate measurement of current change rate to indirectly detect short-circuit conditions, enabling safer and more accurate detection without being directly affected by the harmful current spikes.
3Measurement precision
If duty ratio is adjusted to maintain target current, then feedback control is achieved, but hunting phenomenon occurs when short-circuit exists
Solution Approach 1:
The patent replaces traditional mechanical/current-based detection methods with a computational approach. By using the control unit to calculate current variation |Δi| and compare it against a threshold, the system substitutes direct current measurement and reaction with a computational detection mechanism that can identify short-circuits during hunting without being destabilized by the oscillations.
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
Effectively detects and prevents short-circuits, reduces element damage, and provides clear alerts to the driver through an alarm system, ensuring safe operation and convenient resumption of normal function.
Implementation Method 1
a solenoid includes a coil and a movable valve body
Implementation Method 2
executes feedback control of a drive current for the solenoid, by driving, through pulse width modulation (PWM), a switching element provided on a power supply line to the solenoid
Data Source
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AI summary
A solenoid control device executes feedback control such that a drive current for a solenoid (30) follows a target current, by driving, through PWM, a MOSFET (41) provided on a power supply line to the solenoid (30). An overcurrent detection circuit (46) that outputs an overcurrent detection signal when the drive current for the solenoid (30) reaches an overcurrent determination current value is provided, and it is determined whether an overcurrent is generated. Whether a short-circuit occurs between both terminals of the solenoid (30) is determined by monitoring whether the overcurrent detection circuit (46) is repeating an output of the overcurrent detection signal and a stop of the output of the overcurrent detection signal.