Electronic Switch Drive Circuit for Stable Inductive Load Switching
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Solution Overview
Problem
Transistors used to drive inductive loads face instabilities, particularly at low drive signals and low load currents, leading to potential overheating and current filamentation due to positive thermal feedback, which can result in transistor damage.
Innovation Solution
An electronic circuit with a transistor and a voltage protection circuit that limits voltage between load terminals or between a load terminal and the control terminal, using a control circuit to deactivate the voltage protection based on operation parameters such as drive signal amplitude and load current, preventing the transistor from operating below a temperature-stable point to avoid instabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the transistor is operated at low drive signals and low load currents to dissipate energy, then energy dissipation is achieved, but instabilities occur leading to positive thermal feedback and current filamentation
Solution Approach 1:
The patent implements a control circuit that continuously monitors the drive signal amplitude and load current, and provides feedback control to prevent operation in unstable regions. The control circuit detects when the transistor operates below the temperature-stable point and adjusts the drive signal accordingly to eliminate positive thermal feedback and current filamentation, thereby resolving the contradiction between energy dissipation and transistor stability.
Solution Approach 2:
The patent changes the operating parameters of the transistor by establishing minimum thresholds for drive signal amplitude and load current. The control circuit dynamically adjusts these parameters to keep the transistor operation above the temperature-stable point, preventing instabilities while maintaining energy dissipation functionality. This parameter control approach resolves the contradiction by defining safe operating boundaries.
2Object-affected harmful factors
If the voltage protection circuit is activated to limit voltage between load terminals or between load terminal and control terminal, then voltage protection is provided, but the transistor may operate below the temperature-stable point causing instabilities
Solution Approach 1:
The patent implements a dynamic voltage protection circuit that continuously monitors operation parameters (drive signal amplitude and load current) and adjusts its voltage limiting action accordingly. The control circuit dynamically deactivates the voltage protection when parameters indicate operation below the temperature-stable point, and reactivates it when parameters are within safe ranges. This dynamic control resolves the contradiction by making voltage protection adaptive to operating conditions.
Solution Approach 2:
The control circuit provides feedback control by monitoring operation parameters and adjusting the voltage protection circuit state. When the drive signal amplitude and load current indicate safe operation above the temperature-stable point, the voltage protection is activated; when parameters indicate operation below the stable point, the voltage protection is deactivated. This feedback mechanism resolves the contradiction between voltage protection and transistor stability.
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 stabilizes transistor operation by preventing positive thermal feedback and current filamentation, ensuring safe and reliable operation even at low drive signals and load currents, thereby extending transistor lifespan and preventing damage.
Implementation Method 1
a voltage protection circuit coupled to the transistor and configured to limit a voltage between load terminals or between one of the load terminals and the control terminal to a threshold voltage below an avalanche breakdown voltage of the transistor
Data Source
AI summary
Disclosed is an electronic circuit. The electronic circuit includes a transistor having a control terminal to receive a drive signal, and a load path between a first and a second load terminal. A voltage protection circuit is coupled to the transistor, has a control input, is configured to assume one of an activated state and a deactivated state as an operation state dependent on a control signal received at the control input, and is configured to limit a voltage between the load terminals or between one of the load terminals and the control terminal. A control circuit is coupled to the control input of the voltage protection circuit and is configured to deactivate the voltage protection circuit dependent on at least one operation parameter of the transistor and when a voltage across the load path or a load current through the load path is other than zero.