Igniter Power Semiconductor Device Excess Voltage Protection
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Solution Overview
Problem
Existing power semiconductor devices for igniters face challenges in protecting against transient excess voltages, leading to increased power consumption and size complexity due to current limiting methods and the need for additional components for voltage monitoring.
Innovation Solution
A power semiconductor device with a first semiconductor switching device and an integrated circuit that includes a second semiconductor switching device with a smaller current capacity, a delay circuit, and a thyristor structure, which detects excess voltage before switching on the first semiconductor device, preventing Joule loss and eliminating the need for additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current limiting is performed when current between main terminals is larger than during ordinary operation, then the semiconductor switching device is protected, but the voltage corresponding to the increase in power supply voltage is almost entirely applied between the main terminals causing large Joule loss
Solution Approach 1:
The patent applies preliminary action by detecting excess voltage before the semiconductor switching device is turned on. The excess voltage detection circuit monitors the voltage between main terminals in advance, and when excess voltage is detected, the control circuit prevents the switching device from being energized. This prevents the harmful combination of current limiting during on-state (which causes Joule loss) and instead stops the device before it would draw excessive current, thereby protecting the device while avoiding large energy losses.
2Measurement precision
If direct observation of battery voltage is performed, then excess voltage can be detected, but additional signal taking-in terminal and protective device are required increasing manufacturing cost
Solution Approach 1:
The patent applies self-service by using the semiconductor switching device itself to provide the voltage detection function. The excess voltage detection circuit utilizes the existing main terminals of the switching device to detect the voltage across them. When excess voltage is detected, the control circuit automatically prevents energization of the switching device. This eliminates the need for separate voltage sensing terminals and external protective devices, as the switching device's own terminals and control circuit perform both switching and protection functions.
3Reliability
If Zener diode is provided on terminal for power supply to integrated circuit, then power supply voltage is clamped and regulated, but voltage is fixed substantially at Zener clamp voltage and desired sensitivity cannot be obtained
Solution Approach 1:
The patent applies segmentation by separating the power supply regulation function from the excess voltage detection function. Instead of using a Zener diode that simultaneously performs both clamping and detection (which fixes the voltage and reduces sensitivity), the patent uses the main terminals of the semiconductor switching device specifically for detecting excess voltage. The power supply circuit continues to regulate voltage through the Zener diode, while the detection circuit independently monitors the voltage across the switching device terminals, maintaining full sensitivity for detecting excess voltage conditions.
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
This configuration effectively prevents Joule loss and simplifies the device by allowing early detection of excess voltage, reducing power consumption and device size without the need for additional components, thus enhancing reliability and efficiency.
Implementation Method 1
a third semiconductor switching device including a thyristor structure having a main terminal connected to a high voltage side main terminal of the second semiconductor switching device, the thyristor structure being made conductive by a part of a main current flowing through the energized second semiconductor switching device
Implementation Method 2
a delay circuit delaying a control input signal for driving the first and second semiconductor switching devices so that the second semiconductor switching device is energized prior to the first semiconductor switching device
Implementation Method 3
a first excess voltage detection circuit monitoring voltage on the high voltage side main terminal of the second semiconductor switching device by monitoring conduction of the third semiconductor switching device
Data Source
AI summary
A power semiconductor device for an igniter comprises: a first semiconductor switching device; and an integrated circuit, wherein the integrated circuit includes: a second semiconductor switching device connected in parallel with the first semiconductor switching device and having a smaller current capacity than a current capacity of the first semiconductor switching device; a delay circuit delaying a control input signal so that the second semiconductor switching device is energized prior to the first semiconductor switching device; a third semiconductor switching device including a thyristor structure connected to a high voltage side main terminal of the second semiconductor switching device and being made conductive by a part of a main current flowing through the energized second semiconductor switching device; and a first excess voltage detection circuit stopping the first semiconductor switching device when voltage on the high voltage side main terminal is equal to or more than a predetermined voltage.