Drive Circuit for Target Switch Self-Turn-On Prevention
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Solution Overview
Problem
Existing drive circuits for switches like MOSFETs or IGBTs face issues with self-turn-on due to feedback capacitance, leading to erroneous switching states, and previous solutions involve complex configurations with multiple components and negative voltage sources to prevent this.
Innovation Solution
A drive circuit with a simpler structure using a negative power source, a discharge switch, a reference voltage generator, and a control switch, which selectively applies one of two negative voltages to the main control terminal of the target switch to prevent self-turn-on, reducing the number of components and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple negative voltage sources and switches are used to prevent self-turn-on, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple negative voltage sources into a single negative voltage source that can output different voltage levels. Instead of using separate -15V and -5V voltage sources with multiple switches, the invention uses one voltage source with a voltage selection circuit that switches between different voltage output levels, reducing the overall component count while maintaining the ability to prevent self-turn-on effectively.
Solution Approach 2:
The single negative voltage source is designed to perform multiple functions by outputting different voltage levels (-15V for strong suppression, -5V for mild suppression) based on operating conditions. The voltage selection circuit enables this multi-functionality, allowing the same hardware component to adapt to different scenarios and prevent self-turn-on through appropriate voltage selection rather than requiring dedicated circuits for each voltage level.
2Reliability
If multiple switches are controlled to switch between negative voltages, then self-turn-on prevention is improved, but control complexity increases
Solution Approach 1:
The control functions for multiple switches are merged into a single control circuit that manages the voltage selection. Instead of independently controlling multiple switches across different voltage sources, the invention uses one control circuit to select between voltage levels, simplifying the control logic and reducing the number of control signals required while maintaining effective self-turn-on prevention.
3Device complexity
If a single negative voltage source is used, then device complexity is reduced, but ability to prevent self-turn-on may be compromised
Solution Approach 1:
The single negative voltage source is made dynamic by enabling it to switch between different voltage output levels based on real-time operating conditions. The voltage selection circuit allows the system to adapt the suppression strength dynamically - using stronger suppression (-15V) when needed and milder suppression (-5V) when sufficient, thereby maintaining high reliability with reduced component complexity.
Data Source
AI summary
In a drive circuit, a control switch is electrically connected between a negative voltage source and a reference voltage generator. A drive controller switches a discharge switch and a control switch from an off state to an on state to thereby supply a first negative output voltage to a main control terminal of a target switch. The drive controller switches the discharge switch and the control switch from the on state to the off state to thereby change the first negative output voltage to be supplied to the main control terminal of the target switch to a second negative voltage based on the reference voltage generated by the reference voltage generator. The second negative voltage is more positive than the first negative voltage.