PWM Inductive Load Driver for Fast Solenoid Disconnection Detection
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Solution Overview
Problem
Conventional load drive devices struggle to quickly and accurately detect the disconnection of solenoids in inductive loads, leading to delayed detection and potential engine issues such as blowup and gear shift shock.
Innovation Solution
A load drive device with a microcomputer and driver circuit that includes a current monitoring circuit and disconnection diagnosis circuit, which detects disconnection based on the change in current value, allowing for immediate detection when the change amount is below a predetermined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional current monitoring methods are used to detect solenoid disconnection, then the device can identify abnormality, but the detection is delayed and cannot achieve rapid response
Solution Approach 1:
The patent applies preliminary action by continuously monitoring the change amount of current values in real-time during normal operation. The disconnection diagnosis circuit continuously calculates the difference between adjacent current values and compares it against a threshold, so that when disconnection occurs, the abnormality is detected immediately without waiting for cycle-based averaging or threshold comparisons that cause delays in conventional methods.
Solution Approach 2:
The patent implements feedback by using the monitored current change amount to immediately trigger a disconnection diagnosis result. When the change amount exceeds the threshold, the system provides immediate feedback about the disconnection state, enabling rapid response. This feedback mechanism eliminates the detection delay present in conventional methods by directly linking current monitoring to disconnection diagnosis without intermediate processing steps.
2Object-affected harmful factors
If the solenoid disconnection is not detected quickly, then the system continues operating, but engine blowup and gear shift shock occur due to lack of safe state transition
Solution Approach 1:
The patent applies preliminary action by continuously monitoring current changes and maintaining readiness to diagnose disconnection at any moment. This continuous preliminary monitoring ensures that when disconnection occurs, the system can immediately transition to a safe state without delay, preventing harmful effects such as engine blowup and gear shift shock that would occur with delayed detection.
3Measurement precision
If conventional detection methods are used, then the system structure is simpler, but the detection precision and responsiveness are insufficient for high reliability requirements
Solution Approach 1:
The patent introduces an intermediary element - the disconnection diagnosis circuit - that sits between the current monitoring circuit and the control system. This intermediary continuously processes current values, calculates change amounts, and triggers disconnection diagnosis when thresholds are exceeded. This intermediary structure enhances detection precision and responsiveness without requiring complete system redesign, thus managing complexity while improving performance.
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
Enables rapid and reliable detection of solenoid disconnection, improving the performance and reliability of in-vehicle electronic control devices by quickly transitioning to a safe state.
Implementation Method 1
When the current supply from the battery power supply (VB) is interrupted, a counter electromotive force is generated in the solenoid 110, and a current is supplied from a RETURN ground power supply (GND) through the low-side switching element 50
Data Source
AI summary
A load drive device that drives and controls an inductive load based on a PWM signal from a microcomputer is provided, and the load drive device has excellent reliability and responsiveness capable of quickly detecting disconnection of the inductive load. The load drive device includes a microcomputer and a driver circuit that drives an inductive load by a pulse width modulation signal of a constant cycle based on a control command from the microcomputer, in which the driver circuit includes a current monitoring circuit that monitors a current flowing through the inductive load, and a disconnection diagnosis circuit that detects disconnection of the inductive load based on a current value detected by the current monitoring circuit, and the disconnection diagnosis circuit obtains a change amount of a current value detected by the current monitoring circuit, and when the change amount is equal to or less than a predetermined threshold, determines that the inductive load is disconnected and notifies the microcomputer of the disconnection.