Semiconductor Device Turn-Off Condition Detection Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power semiconductor device driving circuits may malfunction, causing abnormal ignition timing in internal combustion engines, leading to defects, due to incorrect turn-off of the power semiconductor device despite an on-signal input, resulting from potential differences between the control signal and reference potentials.
Innovation Solution
A semiconductor device with a power semiconductor element, a current detector, a turn-off condition detector, and a first switching element that controls the gate potential to prevent incorrect turn-off by using a sensing current proportional to the collector current to ensure the turn-off condition is not met, and a second gate controller to manage the gate current, preventing excessive current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional driving circuit is used to control the power semiconductor device, then the circuit structure is simple, but the circuit may malfunction due to potential differences between control signal and reference potentials, causing incorrect turn-off of the power semiconductor device
Solution Approach 1:
The patent implements feedback by detecting the collector current of the power semiconductor device and using this information to determine whether to maintain the on-state. The turn-off condition detector monitors the control signal and collector current, and only allows turn-off when both indicate appropriate conditions. This feedback mechanism prevents incorrect turn-off caused by potential differences while maintaining circuit reliability.
Solution Approach 2:
The patent introduces a turn-off condition detector as an intermediary component between the control signal input and the gate control. This detector acts as a mediator that validates both the control signal and the actual device state (via collector current detection) before permitting turn-off. This intermediary prevents direct malfunction from potential differences while adding necessary complexity for reliable operation.
2Reliability
If the turn-off condition detector uses both control signal and collector current value for detection, then the reliability of turn-off control is improved, but the device complexity increases due to additional detection circuits
Solution Approach 1:
The patent merges the control signal detection function with the turn-off condition detection function into a single turn-off condition detector. This detector simultaneously processes the control signal and the collector current information to determine turn-off conditions. By combining these functions, the patent reduces the need for separate detection circuits while maintaining high turn-off control accuracy.
Solution Approach 2:
The turn-off condition detector is designed as a multi-functional component that performs both control signal validation and turn-off condition determination. It universally handles multiple detection tasks (control signal level detection, collector current monitoring, and turn-off decision) within a single circuit block, thereby improving reliability without proportionally increasing overall device complexity.
Data Source
AI summary
A semiconductor device includes a power semiconductor element that is connected between a first terminal on a high potential side and a second terminal on a low potential side and that is controlled to be on or off corresponding to a gate potential, a turn-off condition detector that detects whether a control signal input from a control terminal and controlling the power semiconductor element satisfies a predetermined turn-off condition, a first switching element that controls the gate potential of the power semiconductor element to be an off-potential when the turn-off condition detector detects that the turn-off condition is satisfied, and a detector for a collector current of the power semiconductor element. The turn-off condition detector uses the control signal and the collector current as the turn-off condition.