Igniter Power Semiconductor Device Soft Shutoff Circuit
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Solution Overview
Problem
Conventional power semiconductor devices for igniters face challenges in implementing a soft shutoff function without increasing chip size or manufacturing steps, and require complex mechanisms for changing reference voltages, which affect control stability and accuracy.
Innovation Solution
A power semiconductor device with a semiconductor switching device and an integrated circuit that includes a first discharge device for normal operation and a second discharge device for abnormal states, allowing for soft shutoff without changing the reference voltage, thereby maintaining control stability and simplicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a circuit for producing a time constant of about 10 to 100 msec is provided to achieve soft shutoff, then the ignition plug can be protected from sparking during abnormalities, but the chip size is increased or the number of manufacturing steps is increased
Solution Approach 1:
The patent merges the soft shutoff function into the existing overheat protection circuit by utilizing the same discharge path and control structures. The integrated circuit combines both protection functions (overheat and soft shutoff) into a unified design, eliminating the need for separate circuits and reducing chip size while maintaining the time constant of 10-100 msec for preventing ignition plug sparking.
2Reliability
If a mechanism for changing the reference voltage is provided to achieve soft shutoff, then the current limit value can be reduced, but the configuration becomes complicated and control stability is affected
Solution Approach 1:
The patent extracts the soft shutoff control from the complex reference voltage changing mechanism and implements it through a simpler approach. Instead of modifying the reference voltage, the invention uses a dedicated discharge device that directly controls the gate voltage of the semiconductor switching device, simplifying the configuration while achieving the same soft shutoff effect and maintaining control stability.
3Speed
If the reference voltage is changed to reduce the current limit value for soft shutoff, then the shutoff speed can be controlled, but the amplifier requires high accuracy and the configuration becomes more complicated
Solution Approach 1:
The patent introduces a discharge device as an intermediary element between the control circuit and the semiconductor switching device. This discharge device acts as a mediator to control the gate voltage discharge rate, enabling precise control of the shutoff speed without requiring high-accuracy amplifiers or complex reference voltage mechanisms. The discharge device provides a straightforward method to achieve the desired shutoff timing while maintaining system simplicity.
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
The solution enables reliable soft shutoff of the semiconductor switching device during abnormalities without causing ignition plug sparks, ensuring effective protection with a simpler configuration and improved control stability.
Implementation Method 1
a first discharge device discharging charge accumulated on a control terminal of the semiconductor switching device and shutting off the semiconductor switching device so as to generate ignition plug spark voltage
Implementation Method 2
a second discharge device slower discharging the charge accumulated on the control terminal of the semiconductor switching device in comparison with the first discharge device and shutting off the semiconductor switching device so that a voltage on the second side of the ignition coil is equal to or lower than the ignition plug spark voltage
Data Source
AI summary
A power semiconductor device for an igniter comprises: a semiconductor switching device causing a current to flow through a primary side of an ignition coil or shutting off the current; and an integrated circuit driving and controlling the semiconductor switching device, wherein the integrated circuit includes: a first discharge device discharging charge accumulated on a control terminal of the semiconductor switching device and shutting off the semiconductor switching device so as to generate ignition plug spark voltage on a secondary side of the ignition coil during a normal operation; and a second discharge device slower discharging the charge accumulated on the control terminal in comparison with the first discharge device and shutting off the semiconductor switching device so that a voltage on the second side of the ignition coil is equal to or lower than the ignition plug spark voltage during an abnormal state.