Load Driving Diagnosis System Overcurrent Protection
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Solution Overview
Problem
Conventional load driving and diagnosis systems face challenges in managing overcurrent conditions, particularly with semiconductor switching circuits, as they can be damaged by negative currents during breaks, and accurately identifying persistent break states is difficult due to dependencies on terminal capacitor capacitance and parasitic inductor inductance, leading to potential system malfunctions.
Innovation Solution
The system incorporates multiple voltage holding means with selectable voltages and a delay mechanism to ensure reliable breaking of semiconductor switching circuits during overcurrent conditions, along with a state transition mechanism for accurate diagnosis, independent of terminal capacitor or parasitic inductor states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single voltage holding means is used, then the device complexity is reduced, but the reliability of breaking under overcurrent conditions deteriorates due to dependencies on terminal capacitor capacitance and parasitic inductor inductance
Solution Approach 1:
The voltage holding means is segmented into multiple independent voltage holding circuits (first voltage holding circuit and second voltage holding circuit) with different predetermined voltages. This segmentation allows the system to select appropriate voltage levels based on operating conditions, ensuring reliable breaking under overcurrent conditions while reducing dependency on terminal capacitor and parasitic inductor characteristics.
2Reliability
If the breaking speed is increased to prevent damage, then the protection effectiveness is improved, but harmful electromagnetic interference and voltage spikes are generated
Solution Approach 1:
The breaking process is made dynamic through the delay mechanism that introduces a predetermined delay time before activating the breaking operation. This controlled timing allows the system to manage the breaking speed dynamically, preventing harmful electromagnetic interference and voltage spikes while ensuring timely protection when needed.
Solution Approach 2:
The delay mechanism performs preliminary action by introducing a predetermined delay time before the breaking operation is activated. This preliminary timing control ensures that the breaking occurs at the optimal moment, preventing damage while minimizing harmful electromagnetic effects.
3Object-affected harmful factors
If the terminal capacitor capacitance is increased to reduce noise, then the noise protection is improved, but the LC oscillation with parasitic inductor increases causing negative current
Solution Approach 1:
The system changes the voltage parameter by providing multiple voltage holding circuits with different predetermined voltages. By selecting appropriate voltage levels based on operating conditions, the system can maintain noise protection while avoiding the LC oscillation that causes negative current, as the voltage selection compensates for the effects of terminal capacitor and parasitic inductor interactions.
4Reliability
If the break condition holding time is extended to ensure complete breaking, then the breaking completeness is improved, but the response time for normal operation increases
Solution Approach 1:
The delay mechanism performs preliminary timing control by introducing a predetermined delay time before activating the breaking operation. This ensures that the breaking starts at the optimal moment, achieving complete breaking while minimizing the overall response time loss.
Solution Approach 2:
The system rushes through the breaking operation by using the delay mechanism to precisely time the activation, ensuring that the breaking completes quickly and efficiently. This allows the system to achieve complete breaking without excessive delay, maintaining fast response for normal operation.
Data Source
AI summary
A load driving and diagnosis system controls the feed and block of a load current flowing into an inductor such as a solenoid. The load driving and diagnosis system holds a counter-electromotive force, which is developed when the load current is blocked, at a voltage higher than a supply voltage so that the load current will decay for a short time. When an overcurrent condition is established in the load driving and diagnosis system because of a short circuit to a power supply, a malfunction of a circuit or destruction thereof may take place. In addition to a voltage holding means that holds a switching circuit output voltage at a predetermined voltage, a voltage holding means having a different predetermined voltage set therein is included. Moreover, a selection switch that switches the predetermined voltages according to a detected overcurrent condition is included.